Dissertations / Theses: 'Leaching to minerals'

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Catherine, J. H. "The anodic dissolution of copper from complex sulphide minerals." Thesis, University of Exeter, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381574.

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Quezada, Reyes Víctor Alejandro. "Pretreatment to the leaching of copper sulphides minerals in oxidizing media." Doctoral thesis, Universitat de Barcelona, 2021. http://hdl.handle.net/10803/670663.

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La producción chilena de cobre procede de la hidrometalurgia y la concentración; el concentrado de cobre es tratado tradicionalmente mediante pirometalurgia. De acuerdo a Cochilco, el cobre producido en el año 2019, vía hidrometalurgia, fue un 27.3% del cobre chileno producido. Sin embargo, se prevé que esta aporte baje a un 11.6% para el año 2029, debido al agotamiento de los óxidos de cobre y la aparición de los sulfuros, principalmente calcopirita, siendo este mineral refractario a condiciones convencionales de lixiviación. Una opción para mejorar la eficiencia de lixiviación es el pretratamiento, especialmente el efecto del tiempo de curado. Esta variable mejora la cinética de disolución, principalmente en minerales sulfurados de cobre, sin embargo, existe escasa investigación al respecto. Estudios sobre el pretratamiento evalúan el efecto en la eficiencia de lixiviación pero no antes. Además, las reacciones que gobiernan estos fenómenos no han sido identificadas. Así, el objetivo de esta tesis es la evaluación del efecto del curado ácido en la extracción de cobre desde minerales sulfurados en condiciones oxidantes y en la presencia de cloruro. Muestras puras de calcopirita, calcosina y un mineral industrial de mina han sido utilizadas. Se desarrollaron pruebas evaluando el efecto del tiempo de curado y la concentración de KNO3, NaCl y H2SO4 y analizadas por ANOVA (calcopirita). Los productos formados en el pretratamiento (aglomerados) se caracterizaron utilizando diversas técnicas, tales como: Difracción de rayos X, Microscopio electrónico de barrido y Microscopia de luz reflejada. Además, el efecto del pretratamiento ha sido evaluado en la eficiencia de lixiviación a varias temperaturas, los residuos de lixiviación también han sido caracterizados. En el pretratamiento, el mineral de calcopirita y de mina, bajo las condiciones utilizadas en este estudio (15 kg/t of H2SO4, 25 kg/t of NaCl y 15 días de tiempo de curado), los siguientes productos fueron identificados: CuSO4, NaFe3(SO4)2(OH)6, Cu2Cl(OH) y S. Sobre la calcosina, bajo las condiciones utilizadas en este estudio, con 30 kg/t of H2SO4, 40 kg/t of NaCl y 7 días de tiempo de curado, los productos identificados fueron: Cu1.75S, Cu(OH)Cl, Na2SO4 and CuSO4. Finalmente, el pretratamiento mejora la eficiencia de lixiviación, entre 4 y 6%, alcanzando una extracción de cobre de 94% desde la calcopirita a 90 °C, fortaleciendo la hidrometalurgia como alternativa de tratamiento para minerales sulfurados de cobre.
Copper production in Chile is developed by hydrometallurgical and concentration; copper concentrates are traditionally treated by the pyrometallurgical route. According to Cochilco, copper produced in 2019 by hydrometallurgical process represent a 27.3% of Chilean total copper production. However, this contribution is estimated to decrease to 11.6% by 2029, due to the depletion of copper oxides and the appearance of copper sulphides, mainly chalcopyrite, being this mineral refractory to conventional leaching conditions. An alternative to improve leaching efficiency is pretreatment prior to leaching, especially the effect of curing time. This variable can increases the kinetics of copper extraction, especially in sulphides ores, however, there is limited research about it. Studies on pretreatment evaluate the effect on leaching efficiency but not previous leaching. Furthermore, the reactions that govern this phenomenon have not been clearly identified. Therefore, the objective of this thesis is the evaluation of the effect of acid curing on the copper extraction from sulphides minerals in oxidizing media and in presence of chloride. A pure sample of chalcopyrite, chalcocite and a mine ore were used. Tests evaluating the effect of curing time, KNO3, NaCl and H2SO4 concentration have been carried out. The chalcopyrite sample effect was evaluated by ANOVA. The product generated in the pretreatment (agglomerates) has been characterized using different characterization techniques, such as: X-Ray diffraction, Scanning Electron Microscopy and Reflection Optical Microscopy. Furthermore, the effect of pretreatment has been evaluated on the leaching efficiency at different temperatures, leaching residues have also been characterized. In the pretreatment of the chalcopyrite sample and mine ore, under the conditions of 15 kg/t of H2SO4, 25 kg/t of NaCl and 15 days of curing time, the following products were identified: CuSO4, NaFe3(SO4)2(OH)6, Cu2Cl(OH) and S0. Regarding the chalcocite sample, under the conditions of with 30 kg/t of H2SO4, 40 kg/t of NaCl and 7 days of curing time, the following products were identified: Cu1.75S, Cu(OH)Cl, Na2SO4 and CuSO4. Finally, copper sulphides ore pretreatment improved leaching efficiency, between 4 and 6%, reaching a copper dissolution of 94% from chalcopyrite at 90 °C, strengthening the hydrometallurgy as an alternative treatment for copper sulphides ores.

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Al-Harahsheh, Mohammad. "A fundamental investigation into the microwave assisted leaching of sulphide minerals." Thesis, University of Nottingham, 2005. http://eprints.nottingham.ac.uk/11075/.

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Microwave assisted leaching has been investigated in an attempt to improve both the yield of extracted metal and reduce processing time. This is especially pertinent in view of the increased demands for metal and more environmentally friendly processes. This work reports a fundamental study on the influence of microwave energy on the dissolution of sulphide minerals. Chalcopyrite and sphalerite were chosen as model materials due to their economic importance and the diversity of their heating behaviour in a microwave field (chalcopyrite being an excellent microwave heater and sphalerite being an extremely poor microwave receptor). Chalcopyrite leaching has been carried out in ferric sulphate and ferric chloride under both microwave and conventional conditions. Conventionally, it was found that chalcopyrite dissolution in ferric sulphate seems to be limited by surface reaction control. More importantly, it has been shown that specific fracture planes on chalcopyrite particle surfaces experience selective leaching, which was revealed by SEM and ToF-SIMS surface analysis. The preferential attack on particular planes is speculated to be linked to different chemistry of some cleavage planes within the chalcopyrite crystal. In the ferric chloride system, however, it was found that cupric chloride, a reaction product of chalcopyrite with ferric sulphate, may play an important role in the dissolution process. Leaching of both chalcopyrite and sphalerite in ferric sulphate under microwave conditions has shown enhanced recoveries of metal values compared to that produced conventionally. It has been demonstrated that the enhanced copper recovery from chalcopyrite during microwave treatment is as a result of the selective heating of the mineral particles over the solution which was found to be highly lossy. In addition, it is suggested that high loss leaching solutions will develop a superheated layer close to the periphery of the reaction vessel (due to the small penetration depth) which creates localised heating compared to the bulk solution temperature. The enhanced recovery of zinc from sphalerite seems to occur as a result of only the presence of the superheated layer. If leaching takes place within this layer, an apparent rate increase will be noted with respect to the measured bulk temperature. The hypotheses of selective heating (for chalcopyrite) and the effect of penetration depth (for chalcopyrite and sphalerite) were supported by the negligible difference between the activation energy values under microwave and conventional conditions for both chalcopyrite and sphalerite. Furthermore, the measurements of dielectric properties of the leaching solutions have shown that such solutions are highly lossy and characterised by a penetration depth of an order of about 3 mm. Finally, numerical electromagnetic simulations showed that chalcopyrite particles could be heated selectively when micro-waved within highly lossy leaching solutions due to their high conductivity. It is concluded that the dielectric properties of both the solid and liquid phases, the dimensions of the reactor and the position of solid particles within the reactor determine the leaching outcome. More importantly, it is likely that the enhanced recoveries observed are not likely to be as a result of a so called "non-thermal microwave effect" but rather as a result of thermal effects.

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Tasa, Andrus. "Biological leaching of shales : black shale and oil shale /." Tartu : Tartu University Press, 1998. http://bibpurl.oclc.org/web/24619.

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Ayling, K. J. "Chloride leaching of complex sulphide minerals and recovery of copper using the C.E.E.R. cell." Thesis, Open University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253768.

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Crane, Martin John, University of Western Sydney, of Science Technology and Environment College, and of Science Food and Horticulture School. "Geochemical studies of selected base metal minerals from the supergene zone." THESIS_CSTE_SFH_Crane_M.xml, 2001. http://handle.uws.edu.au:8081/1959.7/232.

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Acid leaching of different natural chrysocolla samples under ambient conditions demonstrated that the chemical and chrystallographic inhomogenity significantly affects the rate and that it is virtually impossible to use the mineral as a model for the kinetics of hydrometallurgical processing of copper ores.Dissolution experiments, stability diagrams,and X-ray powder diffraction studies are undertaken and studied in this research and results are given.It is found that a complete solid solution series exists in Nature with most tungstenian wulfenites and molybdenum stolzites containing a range of compositions. The first occurrence of a molybdenum stolzite from Broken Hill, Australia, which also contains small amounts of chromium is noted.Raman microprobe spectroscopy has proven to be a very quick and effective non-destructive method for semi-quantitative analysis of the wulfenite-stolzite and powellite-scheelite solid-solution series and in detecting very small amounts of substituted chromate in wulfenite, stolzite and anglesite
Doctor of Philosophy (PhD)

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Fowler, Terry-Ann. "Kinetics of the ferric sulphate leaching of sphalerite and sphalerite/pyrite mixtures : a study of the chemical leaching of base metal minerals under conditions similar to that of bio-leaching by thiobacilli." Master's thesis, University of Cape Town, 1996. http://hdl.handle.net/11427/21699.

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Bibliography: pages 98-105.
The work presented in this dissertation is an investigation of-the ferric leaching of zinc from sphalerite. A further aspect of this study was an investigation of the influence of pyrite on the dissolution rate of sphalerite due to possible galvanic interactions. This study is one component of a larger study of the sub-processes involved in the bioleaching of sulphide minerals in which the ferric leaching of the sulphide mineral is assumed to be a chemical step with the bacteria oxidising ferrous iron to ferric iron and elemental sulphur, if formed, to sulphate. The literature showed that two types of model have been used to describe the ferric leaching of the sphalerite. The first type was a shrinking-particle model in which there action was described by first order kinetics or an electrochemical mechanism. The second type included a mass transfer resistance in terms of a shrinking-core model described by half-order kinetics or a decaying diffusion coefficient. All four of these models were tested for their ability to predict published data for the ferric leaching of sphalerite. It was found that the models fitted the data for the initial period of a leach up to conversions of about 50%. However, no one of the models was found to be successful in predicting the data for prolonged leaching to high conversions.

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Ewart, D. Keith. "Studies on a moderately thermophilic mixed culture of bacteria and its application to the biooxidation of gold-bearing minerals." Thesis, King's College London (University of London), 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389882.

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Shashikala, A. R. "Role Of Interfacial Phenomena In Bioprocessing Of Minerals Using Bacillus Polymyxa." Thesis, Indian Institute of Science, 2001. http://hdl.handle.net/2005/246.

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In recent years there has been growing interest in bio-mineral processing due to its low operating costs and its application in processing lean-grade ores. Bioprocessing is a good alternative to conventional hydrometallurgy process in mineral processing. In recent times microorganisms have been used as surface modifiers in processes such as froth flotation and flocculation. The surface properties of microbes and minerals such as zeta potential and surface hydrophobicity play a major role in determining adhesion of microorganisms to minerals and hence, the efficiency of flocculation and flotation. These properties also depend on solution conditions such as pH and ionic strength. Adhesion of microorganisms to mineral surfaces can alter the surface properties of the minerals. Such surface modification imparting hydrophobicity or hydrophilicity is used in flocculation and flotation of fine particles. In this research work the effect of ionic strength and pH in deteraiining the surface properties and hence adhesion of the bacterium Bacillus polymyxa to minerals such as hematite, quartz and coal has been studied in detail. The effect of the ionic strength and pH on the electrokinetics of the minerals and bacteria and its subsequent effect on adhesion and flocculation were investigated in detail. Contact angle measurements along with the zeta potential results were used to calculate the interaction energies between the mineral and the microorganism to establish a mechanism for the interaction. The following major conclusions can be drawn from this study. Results indicate that increase in the ionic strength significantly changes the zeta potential of hematite and bacteria without varying the isoelectric point. Increase in the ionic strength caused very little change in the zeta potential of quartz and coal. The adhesion of bacterial cells on to the minerals was found to be dependent on pH, ionic strength and conditioning time. Adhesion of bacterial cells was found to be more on hematite and coal when compared to quartz. The adsorption isotherms of Bacillus polymyxa cells with respect to all the three minerals were found to obey Langmuir isotherm. Flocculation studies demonstrated that the settling rate of hematite and coal was enhanced in presence of bacterial cells and electrolyte. However quartz settled much slower under the same conditions indicating that the quartz particles are being dispersed. Thus, selective flocculation of hematite and coal is possible which can be used in separating them from quartz effectively. The different components of total interaction energy arising from Lifshitz-van der Waal forces, acid/base forces and electrostatic forces were calculated using the van Oss approach. Calculation of the components of the acid base free energy showed that coal and hematite were hydrophobic compared to quartz and the bacterium. From total interaction energy calculation based on the extended DLVO theory, hematite and coal were found to have a net negative interaction energy in acidic pH values and hence attractive forces are predominant. Quartz was found to have a net repulsive energy at all the pH values at low ionic strengths but increase in ionic strength the interaction energy become attractive. The AGLW values of quartz was found to be attractive which is probably responsible for bacterial adhesion onto quartz.

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Crane, Martin John. "Geochemical studies of selected base metal minerals from supergene zone /." View thesis, 2001. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20030721.132607/index.html.

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Thesis (PhD) -- University of Western Sdyney, 2001.
"A thesis presented in accordance with the regulations governing the award of the degree of Doctor of Philosophy, University of Western Sydney" "November 2001" Bibliography: leaves 249 - 254.

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Dikko, Abubakar Umar. "An evaluation of some procedures for assessing the long-term capacity of soil minerals to replenish nutrients lost and the effects of acid deposition." Thesis, University of Aberdeen, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362251.

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A novel system for leaching of reconstituted cores of soils taken from horizons of Calluna moorland podzol profiles derived from granites has been used to see if absolute, or at least, relative, weathering rates assessed by simple leaching techniques and by using the PROFILE model agreed. Initial base cations are first removed by leaching with ammonium acetate. Agreement was reasonable, but the results highlighted problems posed by mineralization effects in column-based procedures. A successful attempt was made to develop a procedure to overcome this problem, based upon pre-oxidation with H₂O₂. This procedure was tested on a selection of B and C horizon soils from podzol profiles, and shown to give weathering rates which correlated well with those derived using the PROFILE model. The equilibrated soil cores remaining at the end of the study were then used for testing the effect of acidification of infiltrating water upon weathering rates of base cations. Weathering rate did not increase regularly to combat the acid input. Intact soil core microcosms, fitted with rhizon samplers at three depths and subjected to appropriate simulated precipitation, have been used to elucidate how land use influences the mobility of copper and zinc. Three land uses were considered, improved pasture, semi-improved pasture, and Calluna moorland. Copper and zinc concentrations were also measured in river water samples collected at 59 points from throughout the River Dee network under diverse flow conditions, with a view to elucidating catchment factors influencing the mobilisation of these two elements into river water. The results demonstrated large inputs of copper arising as a consequence of arable land use, and suggested that TOC in drainage water from moorland soils mobilises copper from mineral sediments in the river network. Both zinc and copper concentrations were increased under high discharge conditions.

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Goldschmidt, Gunther Karl. "Cloning, Sequencing and Partial Characterization of the Accessory Gene Region of Plasmid pTC-F14 isolated from the Biomining Bacterium Acidithiobacillus caldus f." Thesis, Stellenbosch : University of Stellenbosch, 2005. http://hdl.handle.net/10019.1/1588.

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Thesis (MSc (Microbiology))--University of Stellenbosch, 2005.
Plasmid pTC-F14 is a 14.2kb promiscuous, broad-host range IncQ-like mobilizable plasmid isolated from Acidithiobacillus caldus f. At. caldus is a member of a consortium of bacteria (along with Acidithiobacillus ferrooxidans and Leptospirilum ferrooxidans) that is used industrially for decomposing metal sulphide ores and concentrates at temperatures of 40ºC or below which is now a well-established industrial process to recover metals from certain copper, uranium and gold-bearing minerals or mineral concentrates. These biomining microbes are usually obligately acidophilic, autotrophic, usually aerobic iron- or sulphur-oxidizing chemolithotrophic bacteria. Their remarkable physiology allows them to inhabit an ecological niche that is largely inorganic and differs from those environments populated by the more commonly studied non-acidophilic heterotrophic bacteria. At. caldus, is a moderately thermophilic (45 to 50ºC), highly acidophilic (pH1.5 to 2.5) sulphur-oxidizing bacterium, and its role as one of the major players in the industrial decomposition of metal sulphide ores has become evident in recent years. At. caldus f from which pTC-F14 was isolated was found to be one of two dominant organisms in a bacterial consortium undergoing pilot-scale testing for the commercial extraction of nickel from ores.

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Antoniassi, Juliana Lívi. "Caracterização tecnológica de recursos minerais de terras raras em complexos alcalinos e alcalino-carbonatíticos do Brasil." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3134/tde-27112017-143927/.

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Este trabalho enfocou o levantamento de informações químicas e mineralógicas de detalhe em amostras de depósitos alcalinos e alcalino carbonatíticos brasileiros contento terras raras, de modo a fornecer subsídios para o desenvolvimento de processos de aproveitamento. Estes depósitos apresentam elevados volumes de recursos, baixos teores de elementos de terras raras (essencialmente terras raras leves) e elevada complexidade mineralógica. As amostras estudadas são provenientes de depósitos lateríticos, com teor total de óxidos de terras raras entre 1,27 e 6,45%, sendo a monazita o principal mineral portador desses elementos, exceto em uma das amostras, onde é predominante a bastnaesita; como minerais traços estão presentes cerianita, xenotima e um fosfato de escândio. Os minerais de terras raras tendem a concentrar-se em direção às frações granulométricas mais finas, mostram d50 de 15 µm nas frações acima de 0,008 mm e chegam a valores inferiores a 0,1 µm abaixo da mesma. Esses minerais ocorrem preferencialmente em íntimas associações com a ganga, sendo que valores superiores a 60% de liberação (em área) são observados apenas nas frações menores que 0,020 mm. O potencial de concentração desses minerais foi avaliado por separações físicas e extração hidrometalúrgica. Separações físicas em líquidos densos e magnéticas não possibilitaram a obtenção de produtos enriquecidos em terras raras. O resultado mais promissor refere-se à possibilidade de remoção de um produto contaminante magnético nas frações retidas em 0,020 mm e que responde por 30% do total de Fe2O3 contido nas amostras (em média), sem perdas significativas das terras raras. A condição experimental otimizada para a dissolução seletiva dos minerais de terras raras em meio ácido foi estabelecida a partir de um planejamento experimental baseado em princípios estatísticos. Para o material cominuído abaixo de 0,30 mm, a solubilização dos óxidos de terra raras é de 77%, considerando-se ácido sulfúrico concentrado, reduzida porcentagem de sólidos, temperatura ambiente e tempo de 4 horas. Maiores níveis de solubilização das terras raras podem ser alcançados, mas juntamente com elevação da solubilização da ganga.
This work focused on the acquisition of chemical and mineralogical detailed information in samples from Brazilian alkaline and alkaline-carbonatitic deposits containing rare earths, in order to provide subsidies for process development. These deposits present high volumes of resources, low contents of rare earth elements (essentially light rare earths) and high mineralogical complexity. The studied samples are lateritic materials, with a total content of rare earth oxides between 1.27 and 6.45%, being monazite the main rare earth bearing mineral, except in one of the samples, where bastnaesite is predominant; cerianite, xenotime and a scandium-phosphate occur as trace. Rare earth minerals tend to enrich toward the finest sieve fractions with an medium grain size of 15 µm in the fractions greater than 0.008 mm and decreasing below 0.1 µm in finer fractions. These minerals occur preferentially in intimate associations with the gangue; liberation greater than 60% (in area) are observed under 0.020 mm fractions. The concentration potential of these minerals was evaluated through physical separation and hydrometallurgical extraction. Physical separations (heavy liquid and magnetic) did not succeed in obtaining products enriched in rare earths. The most promising result were the possibility of removing magnetic phases above 0.020 mm (responsible for 30%, on average, of the total Fe2O3 contained in the samples) without significant losses of rare earths. The rare earths acid leaching protocols and conditions were established by statistical experimental design. For samples comminuted below 0.30 mm, the best rare earths solubilization (77%) and with minimum gangue leaching was obtained in concentrate sulfuric acid, low solids concentration, environmental temperature and four hours of reaction. Higher levels of rare earths solubilization can be achieved, however accompanied by higher gangue solubilization.

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Laubscher, Sydney. "MANGANESE UPTAKE IN RED MAPLE TREES IN RESPONSE TO MINERAL DISSOLUTION RATES IN SOIL." Kent State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=kent1574431912056187.

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Kotze, Andries Albertus. "Analysis of arsenic resistance in the biomining bacterium, Acidithiobacillus caldus." Thesis, Stellenbosch : University of Stellenbosch, 2007. http://hdl.handle.net/10019.1/17374.

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Thesis (MSc)--University of Stellenbosch, 2006.
ENGLISH ABSTRACT: In this study the chromosomal arsenic resistance (ars) genes shown to be present in all Acidithiobacillus. caldus isolates were cloned and sequenced from At. caldus #6. Ten open reading frames (ORFs) were identified on a clone conferring arsenic resistance, with three homologs to arsenic genes, arsC (arsenate reductase), arsR (regulator) and arsB (arsenite export). This ars operon is divergent, with the arsRC and arsB genes transcribed in opposite directions. Analysis of the putative amino acid sequences of these arsRC and arsB genes revealed that they are the most closely related to the ars genes of Acidithiobacillus ferrooxidans. These ars genes were functional when transformed into an Escherichia coli ars deletion mutant ACSH50Iq, and conferred increased levels of resistance to arsenate and arsenite. ArsC was required for resistance to arsenate, but not for resistance to arsenite. None of the other ORFs enhanced arsenic resistance in E. coli. A transposon located arsenic resistance system (TnAtcArs) has been described for highly arsenic resistant strains of the moderately thermophilic, sulfur-oxidizing, biomining bacterium At .caldus #6. In the latter study it was shown that TnAtcArs confers higher levels of resistance to arsenate and arsenite than the chromosomal operon. TnAtcArs was conjugated into a weakly ars resistant At. caldus strain (C-SH12) and resulted in greatly increased arsenite resistance. RT-PCR analysis revealed that arsR and arsC are co-transcribed. Despite ORF1 (cadmium inducible-like protein) and ORF5 (putative integrase for prophage CP-933R) not being involved in resistance to arsenic, ORF1 was co-transcribed with arsRC and ORF5 with arsB. Using arsR-lacZ and arsB-lacZ fusions it was shown that the chromosomal ArsR-like regulator of At. caldus acts as a repressor of the arsR and arsB promoter expression. Induction of gene expression took place when either arsenate or arsenite was added. The chromosomal located ArsR was also able to repress TnAtcArs, but the transposon-located ArsR was unable to regulate the chromosomal system.
AFRIKAANSE OPSOMMING: In hierdie studie is die chromosomale arseen weerstandbiedendheidsgene (ars gene), teenwoordig in alle Acidithiobacillus caldus isolate, gekloon en die DNA volgorde daarvan vanaf At. caldus #6 bepaal. Tien oopleesrame (ORFs) is geïdentifiseer op ‘n kloon wat arseen weerstandbiedend is, met drie homoloog aan ars gene, nl. arsC (arsenaat reduktase), arsR (reguleerder) en arsB (membraan-geleë pomp wat arseniet uitpomp). Die ars operon is gerangskik met die arsRC en arsB gene wat in teenoorgestelde rigtings getranskribeer word. Analise van die afgeleide aminosuurvolgorde van dié ars gene het getoon hulle is naverwant aan die ars gene van Acidithiobacillus ferrooxidans. Die ars gene was funksioneel na transformasie na ‘n E. coli ars mutant (ACSH50Iq), en het ‘n hoër vlak van weerstand teen arsenaat en arseniet gebied. ArsC was nodig vir weerstand teen arsenaat, maar nie vir weerstand teen arseniet nie. Geen van die ander ORFs het arseen weerstandbiedendheid in E. coli bevorder nie. Voorheen is ‘n ars operon, geleë op ‘n transposon (TnAtcArs), in ‘n hoogs arseen-weerstandbiedende stam van die middelmatige termofiliese, swawel-oksiderende, bio-ontgunning (“biomining”) bakterie Acidithiobacillus caldus #6 beskryf. In laasgenoemde studie is gevind dat TnAtcArs hoër vlakke van weerstand bied teen arsenaat en arseniet as die chromosomale operon. TnAtcArs is na ‘n lae arseen-weerstandbiedende At. caldus stam (C-SH12) gekonjugeer. Die resultaat was ‘n groot verhoging in arseen weerstandbiedendheid. RT-PCR analise het onthul dat arsR en arsC saam getranskribeer word. Benewens die feit dat ORF1 (kadmium induseerbare protein) en ORF5 (afgeleide integrase vir profaag CP-933R) nie betrokke is in weerstand teen arseniet and arsenaat nie, is ORF1 saam met arsRC getranskribeer en ORF5 saam met arsB. Deur gebruik te maak van die fusie-gene arsR-lacZ en arsB-lacZ is bewys dat die chromosomale ArsR reguleerder van At. caldus as ‘n inhibeerder van die arsR en arsB promoter uitdrukking funksioneer. Indusering van geen uitdrukking vind plaas wanneer arseniet of arsenaat bygevoeg word. Die chromosomaal-geleë ArsR is ook in staat om TnAtcArs te inhibeer, terwyl die transposon geleë ArsR nie daartoe in staat is om die chromosomale ars sisteem te reguleer nie.

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Nicolau, Paula Bacelar V. C. "Novel iron-oxidising acidophilic heterotrophic bacteria from mineral leaching environments." Thesis, Bangor University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321390.

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Close, Thomas Jr (Thomas Charles). "Kinetic analysis of leaching reactions in multi-component mineral systems." Thesis, Massachusetts Institute of Technology, 2021. https://hdl.handle.net/1721.1/130666.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, February, 2021
Cataloged from the official PDF of thesis.
Includes bibliographical references (pages 167-177).
The rational design of reactive systems requires the use of kinetic models of system behavior. However, the development of such models for multicomponent systems is complicated by conditions of mutual interference in determining reaction rates. Addressing this shortcoming for mineral systems requires developing methods to solve the fundamental problem of identity and resolve the partitioning of system behavior between components. In this work a complete description of the problem of simultaneous rate determination under conditions of mutual interference is developed and progress towards solving this problem in microfluidic and bulk systems is presented. Results show that there are unique challenges posed in microfluidic systems that hinder the ability to accurately partition the behavior of the total system between its constituents. In contrast, the bulk system permits a practical experimental solution based on particle size and shape for certain classes of solid mixtures.
by Thomas Close.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Chemical Engineering

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NISTI, MARCELO B. "Lixiviação de metais e radionuclídeos em solos tropicais condicionados com fosfogesso." reponame:Repositório Institucional do IPEN, 2016. http://repositorio.ipen.br:8080/xmlui/handle/123456789/27137.

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O fertilizante fosfatado brasileiro é obtido pela reação por via úmida da rocha fosfática de origem ígnea com ácido sulfúrico concentrado, obtendo como produto final, o ácido fosfórico e como resíduo, o fosfogesso, que é estocado em pilhas, a céu aberto, junto às instalações produtoras. Parte do fosfogesso vem sendo utilizada na agricultura como condicionador de solos, devido a sua alta solubilidade, podendo melhorar a estrutura do solo, reduzir a erosão do solo, aumentar os níveis de enxofre e fósforo disponíveis e melhorar a composição dos fertilizantes. Mas a presença de radionuclídeos e metais no fosfogesso impõem restrições sobre o uso na agricultura. Para garantir uma utilização segura, é importante estimar a lixiviação dos radionuclídeos e metais presente no fosfogesso. O objetivo deste trabalho foi estudar a disponibilidade dos radionuclídeos relevantes do ponto de vista radiológico (238U, 232Th, 226Ra, 228Ra, 210Pb e 210Po) e dos metais (As, Cd, Cr, Ni, Se, Hg e Pb) presentes no fosfogesso de procedência brasileira, levando em consideração sua aplicação em solo agricultável. Para esta finalidade, foi desenvolvido um protocolo experimental em escala de laboratório, no qual colunas foram preenchidas com misturas de solos arenosos e argilosos típicos brasileiros condicionados com fosfogesso. A essas colunas foi adicionada água, a fim de se alcançar uma extração branda desses elementos. Foi implantado um procedimento analítico para a determinação sequencial dos radionuclídeos de interesse na solução obtida na lixiviação. As frações disponíveis foram obtidas utilizando-se a razão entre as concentrações dos radionuclídeos no lixiviado e as concentrações dos radionuclídeos nas amostras de solo, solo condicionado com fosfogesso e fosfogesso. Os valores de concentração dos radionuclídeos 238U, 232Th, 226Ra, 228Ra, 210Pb e 210Po obtidos no fosfogesso das duas procedências variaram de 86 Bq kg-1 a 352 Bq kg-1. As concentrações de 226Ra e 228Ra obtidas no fosfogesso ficaram abaixo do limite máximo permitido pela resolução da Comissão Nacional de Energia Nuclear, atendendo às condições necessárias para o seu uso na agricultura. Os resultados obtidos para os metais As, Cd, Cr, Ni, Pb, Se e Hg no fosfogesso foram inferiores ao limite máximo para condicionador de solo e para fertilizantes estabelecidos pelo Ministério da Agricultura, Pecuária e Abastecimento, atendendo às condições necessárias para o seu uso na agricultura. Os radionuclídeos 226Ra, 210Pb, 210Po e 228Ra apresentaram frações disponíveis nos solos e solos condicionados com fosfogesso variando de 0,05% a 1,2%; para o 238U e 232Th as frações disponíveis apresentaram valores inferiores a 0,05%. Os metais apresentaram frações disponíveis nos solos e solos condicionados com fosfogesso variando de 0,05% a 1,07%. Os resultados obtidos para a fração disponível de metais e radionuclídeos no solo condicionado com fosfogesso demostraram que mesmo utilizando concentrações de fosfogesso dez vezes acima da dose recomendada, a disponibilização foi desprezível. Pode-se concluir que a utilização do fosfogesso como condicionador de solos é viável, no que concerne a disponibilidade dos metais e radionuclídeos estudados.
Tese (Doutorado em tecnologia Nuclear )
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

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19

Hall, Stephen Thomas. "Enhancement of magnetic susceptibility by leaching and application in mineral separation." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=71807.

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Enhancement of the magnetic susceptibility of pyrite particles is observed following a mild oxidative pressure leach. This increase is studied for a range of experimental conditions. The increase in susceptibility is attributed to the formation of a thin layer of ferromagnetic oxides. This layer of leach reaction products has been extensively studied using various analytical techniques. The species identified are (gamma)-Fe(,2)O(,3) and Fe(,3)O(,4), which supports a previously postulated reaction model.
This leach treatment significantly increases the magnetic susceptibility of coal-pyrite permitting improved high-gradient magnetic desulfurization of a high pyritic sulfur coal.
The leach treatment also enhances the magnetic susceptibility of other iron-containing mineral sulfides. However, application of this leach pretreatment in sulfide/sulfide separations is limited due to galvanic coupling effects which passivate the susceptibility increase reaction. In the presence of oxides, coal and probably other non-sulfides passivation does not occur and the susceptibility of the iron-bearing sulfide increases. The potential exists for the application of the leach as a pretreatment in enhancing fine iron-containing sulfide/non-sulfide magnetic separations.

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20

Abrahamsson, Filip. "Leaching of Pyrrhotite from Nickel Concentrate." Thesis, Luleå tekniska universitet, Industriell miljö- och processteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-64934.

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Non-oxidative acid leaching of pyrrhotite from Kevitsa’s Ni-concentrate and methods to recover by-products, have been investigated. Selective dissolution of pyrrhotite (Fe1-xS, 0<x<0.25) can enrich the content of the valuable metals, such as Ni and Co, in the final concentrate and will reduce the amount of Fe and S sent to the smelters. The pyrometallurgical smelting of leached concentrate will thus give less formation of smelter by-products in form of slag and SO2. The leaching was studied through an experimental design plan with parameter settings of 38.8% to 57.8% H2SO4 and temperatures from 60 to 100°C. The best results were obtained in experiments carried out at the lower experimental range. Leaching at 60°C with an initial acid concentration of 38.8% H2SO4 was found sufficient to selectively dissolve most of the pyrrhotite; leaving an enriched solid residue. A QEMSCAN analysis of the solid residue confirmed that most of the pyrrhotite had been dissolved and showed that pentlandite was still the main Ni-mineral. Chemical assays showed that more than 95% of the Ni, Co, and Cu remained in the final residue. The utilized leaching process generates by-products, in the form of large quantities of Fe2+ in solution and gaseous H2S. To recover Fe2+, crystallization of iron(ii) sulfate (FeSO4∙nH2O) from leach solution through cooling have been studied. The crystallized crystals were further dehydrated into the monohydrate (FeSO4∙H2O) through a strong sulfuric acid treatment (80%H2SO4). XRD analysis confirmed that FeSO4∙H2O was the main phase in the final crystals, and a chemical analysis showed a Fe content of about 30%, 1.5% Mg, 0.4% Ca, and 0.2% Ni. The possibility to leach the concentrate by circulating the acidic solution from the crystallization stage has been tested. The recirculation of the solution showed no negative effects, as the recoveries of elements and chemical assays of the final solid residue were found to be similar to the obtained assay when the concentrate was leached in a fresh solution.
Icke-oxidativ syralakning av magnetkis från Kevitsas Ni-koncentrat har studerats samt metoder för tillvaratagande av biprodukter. Genom en selektiv upplösning av magnetkis (Fe1-xS, 0<x<0.25) kan värdefulla metaller som Ni och Co anrikas i det slutliga koncentratet. Samtidigt som mängden Fe och S som skickas till smältverken minskar, vilket också innebär att mindre biprodukter i form av slagg och SO2 erhålls vid den pyrometallurgiska smältningen av Ni-koncentratet. En experimentell design plan genomfördes för att studera lakningen där syrakoncentrationen varierades från 38.8% till 57.8%H2SO4 och temperatur från 60 till 100°C. Bäst resultat erhölls vid de lägre parameterinställningarna. Lakning vid 60°C med en initial syrakoncentration på 38.8%H2SO4 visade sig vara tillräcklig för att selektivt lösa upp merparten av all magnetkis och lämna kvar en anrikad produkt. Via QUEMSCAN bekräftades att merparten av all magnetkis hade löst upp sig och att huvudsakligt Ni-mineral fortfarande var pentlandit. Kemiska analyser visade att mer än 95% av Ni, Co och Cu stannade kvar i fasta godset. Den tillämpade lakningsmetoden genererar biprodukter i form av stora mängder Fe2+ i lösning och H2S i gasform. För att tillvarata Fe2+ har kristallisering av laklösning som järn(ii) sulfat (FeSO4∙nH2O) studerats genom kylning. De kristalliserade kristallerna avvattnades till monohydrat, FeSO∙1H2O, genom avvattning i stark svavelsyra (80%H2SO4). XRD bekräftade FeSO∙1H2O som huvudfas i slutliga kristallerna och kemisk analys visade på ca 30%Fe med huvudsakliga orenheter i form av 1.5% Mg, 0.4%Ca och 0.2% Ni. Möjligheten till att laka i återcirkulerad lösning efter kristallisering har undersökts. Lakning i återcirkulerad lösning visade inga negativa effekter då liknande halter och utbyten erhölls till det fasta godset.

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21

Yahya, Abidah. "Physiological and phylogenetic studies of some novel acidophilic mineral-oxidising bacteria." Thesis, Bangor University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322564.

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22

Guzman, Grijalva Hector Manuel. "Arsenic Leaching from Mineral Sorbents under Landfill Conditions and Arsenic Transport by Wind." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/347223.

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The capacity of four mineral sorbents to retain arsenic under simulated mature landfill conditions was tested using semi-batch and continuous flow columns. The sorbents tested were Fe-, Ti-, La-, and Zr- based oxi(hydroxides). The Fe sorbent was included as a positive control to compare the release of As from a substrate subject to reduction to those of the, non-sensitive to reduction under typical mature landfill conditions, Ti, La, and Zr media. It has been proved that under mature landfill conditions, As(V) preloaded on ferric sorbents is prompt to be released at high levels. Our results indicate that Ti, La, and Zr sorbents can release As at a similar or higher degree than a ferric sorbent. In a second phase, the capacity of the same sorbents to retain As was evaluated after being subject to polymeric encapsulation in an epoxic resin. Landfill conditions were simulated by use of semi-batch column systems packed with compost and fed with actual landfill leachate. Results obtained indicated that encapsulation highly enhanced As retention of the media under simulated landfill conditions. In our research regarding soil contamination by atmospheric transport from mine tailings, a previously developed deposition forecasting model (DFM) that is designed to model the transport of particulate As and Pb from mine tailing impoundments is verified using dust collection and topsoil measurements. The forecast deposition patterns are compared to dust collected by inverted-disc samplers through gravimetric, chemical composition and lead isotopic analysis. The DFM is capable of predicting dust deposition patterns from the tailings impoundment to the surrounding area. Finally, the bioaccessibility of As and Pb were on samples collected at Iron King Mine Tailing was evaluated through chemical extractions using simulated the gastric and the lung fluids of the human body. Results obtained indicate that extractions using simulated gastric fluid lead to As concentrations one order of magnitude higher to those obtained with lung fluid. For Pb concentration the difference was greater than 2 orders of magnitude.

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Vemic, Mirjana. "Leaching and recovery of molybdenum, nickel and cobalt from metals recycling plants mineral sludges." Thesis, Paris Est, 2015. http://www.theses.fr/2015PESC1106/document.

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Compte tenu de l'épuisement en cours des ressources naturelles qui ont lieu dans le monde entier, le prix élevé, la forte demande et la pénurie future des ressources minérales primaires pour Mo, Ni et Co, il est extrêmement important de mettre en œuvre le recyclage des métaux/récupération/réutilisation partir des demi-finis produits, sous-produits, des matériaux secondaires et des déchets, y compris les déchets dangereux (ce est à dire des catalyseurs usés, boues minérales). En outre, il est nécessaire d'utiliser des technologies plus efficaces pour récupérer des métaux à partir de déchets/ressources secondaires afin de minimiser les dépenses en capital, l'impact environnemental et de répondre à l'augmentation de la demande de métal. Parmi les différentes ressources secondaires, les catalyseurs usés et les boues minérales générés aux catalyseurs usés usines de recyclage pourrait être une très bonne ressource secondaire, car ils contiennent des concentrations élevées de métaux différents (en particulier Mo, Ni et Co). Par conséquent, ils doivent être considérés comme une ressource et non comme un déchet. Dans notre étude, nous traitons avec le catalyseur, l'oxyde métallique et le recyclage des piles minérales de la plante boues. Ce type de matériau contient de fortes concentrations de métaux différents. Cependant, au mieux de nos connaissances de spéciation, lixiviation et de récupération des propriétés de ce type de matériel n'ont pas été étudiés auparavant. Boues minérales a été minutieusement caractérisée où le pH, La perte au feu (LOI), Toxicité Caractéristique Lixiviation Procédure (TCLP), Diffraction des rayons X (XRD), Microscopie électronique à balayage (SEM) avec dispersion d'énergie des rayons X spectroscopie (EDS), Total Métal Contenu (TMC) et Extraction Séquentielle (SE) ont été effectuées. Sur la base des résultats de la caractérisation des boues minérales, le taux de lixiviation et les rendements de Mo, Ni et Co à partir de l'échantillon de boue minérale ont été quantifiés. Différents réactifs de lixiviation (autonome acides (nitrique, sulfurique et chlorhydrique) et les mélanges d'acides (eau régale (nitrique + chlorhydrique (1:3)), nitrique + sulfurique (1:1) et nitrique + sulfurique + chlorhydrique (2:1:1)) ont été étudiés à changer les paramètres de fonctionnement (solides ratio liquide, le temps de lixiviation et de la température), afin de comprendre les caractéristiques de lixiviation et sélectionnez le réactif de lixiviation approprié qui permet d'atteindre les plus hauts rendements de lixiviation de métal. Acide sulfurique (H2SO4) a été trouvé d'être le produit de lixiviation avec le potentiel de lixiviation des métaux les plus élevés. Les conditions de lixiviation optimales étaient une lixiviation en trois étapes successives, la température de 80°C, le temps de lixiviation 2 h, et S/L rapport 0.25 g L-1. Dans ces conditions, les rendements de lixiviation à partir de notre échantillon de boue minérale a atteint 85.5, 40.5 et 93.8% pour Mo, Ni et Co, respectivement
In view of the on-going depletion of the natural resources taking place worldwide, the high price, high demand and future shortage of the primary mineral resources for Mo, Ni and Co it is extremely important to implement metals recycling/recovery/reuse from semi-finished products, by-products, secondary materials and wastes, including hazardous waste (i.e. spent catalysts, mineral sludges). Furthermore, there is a need to utilize more efficient technologies to recover metals from wastes/secondary resources in order to minimize capital outlay, environmental impact and to respond to the metal increased demand. Among the different secondary resources, spent catalysts and mineral sludges generated at the spent catalysts recycling plants could be a very good secondary resource, as they contain high concentrations of different metals (especially Mo, Ni and Co). Therefore, they should be viewed as a resource, not as a waste. In our study we are dealing with the catalyst, metallic oxide and battery recycling plant mineral sludge. This type of material contains high concentrations of different metals. However, to the best of our knowledge, speciation, leaching and recovery of Mo, Ni and Co from this type of material were not investigated before. Mineral sludge was minutely characterized where pH, Loss On Ignition (LOI), Toxicity Characteristic Leaching Procedure (TCLP), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray Spectroscopy (EDS), Total Metal Content (TMC) and Sequential Extraction (SE) were performed. Based on the mineral sludge characterization results the leaching rate and yields of Mo, Ni and Co from mineral sludge sample were quantified. Different leaching reagents (stand-alone acids (nitric, sulfuric and hydrochloric) and acid mixtures (aqua regia (nitric + hydrochloric (1:3)), nitric + sulfuric (1:1) and nitric + sulfuric + hydrochloric (2:1:1)) were investigated at changing operational parameters (solid to liquid ratio, leaching time and temperature), in order to understand the leaching features and select the suitable leaching reagent which achieves the highest metal leaching yields. Sulfuric acid (H2SO4) was found to be the leachant with the highest metal leaching potential. The optimal leaching conditions were a three stage successive leaching, temperature 80°C, leaching time 2 h and S/L ratio 0.25 g L-1. Under these conditions, the leaching yields from our mineral sludge sample reached 85.5, 40.5 and 93.8% for Mo, Ni and Co, respectively

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Bertilsson, Olle. "Study of leaching behavior of tin in Zinc-clinker and Mixed Oxide." Thesis, Luleå tekniska universitet, Industriell miljö- och processteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-69941.

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Due to the increasing usage of Sn in different electronics, such as solders and in touchscreens, together with Boliden Rönnskärs increased intake of electronic waste as a secondaryraw material, a Zn-containing product called Zn-clinker has increasing amounts of Sn. TheZn-clinker is shipped to Boliden Zn-smelter in Odda, where the Zn-clinker is mixed in withcalcine (roasted concentrate) and leached in several steps. Since Zn-clinker is a product froma halogen removal in a clinker-furnace, the feed material (Mixed Oxide), for this furnace, wasalso investigated since there are plans to replace clinkering with soda-washing in the future.Most of the Sn ends up in the leaching residue which then is deposited in the mountaincaverns close by the Boliden Odda smelter. Boliden is studying the possibility to recoverPb/Ag and Sn content from the leaching residue and create a valuable by-product. Bystudying how the leaching of Sn behaves, together with a characterization of the materials, thefollowing question should be answered: “During which sulphuric acid leaching conditions, ofZn-clinker and Mixed Oxide, is the leaching of Sn minimized?” The leaching results for Zn-clinker showed that 8-10% Sn will leach out, despite changingtemperature, redox potential, time and pH. A characterization of the material with SEM-EDSand XRD-analysis was also conducted to see if Sn could be identified in any phases in thematerials. The studies provided enough evidence that Zn2SnO4 could be concluded to be themain phase in the leaching residue for Zn-clinker, a form that would not leach underconditions presented in this project. However, 8-10% of the Sn will come together with Feand when Fe leach out, so does Sn. The leaching results for Mixed Oxide pointed towards that different phases from them foundin Zn-clinker was present. Sn losses varied between 10-20% but raised to 47% whentemperature was changed to 80 °C during leaching. The SEM-EDS analysis showed that theidentified Sn-phases contained more Sn than in Zn-clinker and together with the leachingresults, a conclusion that Sn would mainly be found as SnO2 or SnO in the Mixed Oxide, butthere is still uncertainty about the distributions of these forms. Unfortunately half of the As leached out during the soda-washing for Mixed Oxide, creating aleachate with Cl, F and As that need to be taken care of. This could be challenging andpresenting a costly side-project for the route different from the Zn-clinker route used today.Another observation was that PbCO3 formed during the soda-washing, a phase that willconsume more sulphuric acid during leaching.

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Sampson, Mark Ian. "Influence of the cell properties of acidophilic bacteria during attachment to mineral sulfides and consumption during the oxidation of ferrous iron." Thesis, University of Exeter, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297789.

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Bouchet, Alain. "Minéralogie et géochimie des roches altérées du chapeau de fer de Rouez (Sarthe)." Poitiers, 1987. http://www.theses.fr/1987POIT2303.

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L'oxydation de la pyrite provoque un lessivage de l'aluminium de plus en plus important vers la base de la zone oxydee. Le comportement du magnesium et de l'aluminium entraine la cristallisation de differents mineraux argileux interstratifies desordonnes dans les zones oxydees, intermediaires et cementees. Sous la zone cementee, les mineraux argileux des pelites sont remplaces par un assemblage interstratifie caracteristique de milieux acides. Dans la zone oxydee, les chlorites se transforment en interstratifie chlorite/saponite ferrifere. La composition de la saponite evolue vers celle de la stevensite ferrifere a la base de la zone oxydee. Dans la zone cementee, le fer est piege dans les sulfures. Les chlorites primaires sont totalement detruites par l'action des fluides acides

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Bueno, Guilherme Wolff. "Impacto ambiental do fósforo em rações para tilápia do Nilo (Oreochromis niloticus)." Universidade Estadual do Oeste do Parana, 2011. http://tede.unioeste.br:8080/tede/handle/tede/1964.

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The relationship between men and environment has always been marked by anthropocentric logic, in which distinguishes man from nature and is elevated to the title and source of all other values. Under this logic, man has caused many environmental impacts, bringing to society some irreversible damages. However, this view is being increasingly criticized and revised. The global tension facing the responsibility in producing in a sustainable way, given that water resources are limited, drives a new global context, which requires a different way of thinking and acting. Therefore, the activity represented by aquaculture producers and entrepreneurs, feed mills, regulatory agencies, educational and research institutions may establish codes of conduct and environmentally responsible management practices in order to minimize the environmental impacts of animal production. Therefore, the objective of this study consisted of two experiments to determine the environmental impact in the aquatic environment of phosphorus in diets for juvenile Nile tilapia (Oreochromis niloticus). In this context, the first experiment discusses the influence of different levels of phosphorus in the diet and the emission of effluents from the fish culture. We used 120 juvenile O. niloticus with mean weight of 85.11 ± 0.34 g to evaluate two levels (0.8 and 1.2%) of total phosphorus in the diet, to determine the apparent digestibility of phosphorus in the diets using chromic oxide (Cr2O3) incorporated in the rate of 0.1% in the diets. And to verify how the use of different ingredients in the diet will meet the requirements for tilapia and the total phosphorus in wastewater generation, total phosphorus digestibility, pellets stability in water, and minerals leaching in water from the diet were evaluated and quantified the waste generated to produce a ton of tilapia. Six isonitrogenous and isocaloric diets were formulated containing 28% crude protein and 3000 kcal DE / kg with levels of 0.8% of total phosphorus, using dicalcium phosphate, meat and bone meal, poultry offal meal, anchovy meal, tilapia waste and bone meal as ingredients. We conclude that the use of 0.8% of total phosphorus promotes a better control of water quality and can be used as a nutritional strategy for reducing effluent from aquaculture. As for the ingredients, the best efficiency for total phosphorus was 83.74% for dicalcium phosphate, 77.73% for anchovy meal, 75.27% for tilapia meal and 73.42% for poultry meal in diets for juvenile Nile tilapia. Therefore through a balanced animal nutrition is possible to reduce the metabolites excretion in the water, reaching an adequate fish production with less environmental impact.
A relação da humanidade com o meio ambiente sempre foi marcada pela lógica antropocêntrica, na qual o homem distingue-se da natureza e é elevado ao título de fonte de todos os demais valores. Sob tal lógica, os homens provocaram inúmeros impactos ambientais, trazendo para a sociedade atual danos que podem ser irreversíveis. Todavia, tal visão está sendo cada vez mais criticada e revista. A tensão mundial frente à responsabilidade de se produzir com sustentabilidade, uma vez que os recursos hídricos são limitados, impulsiona um novo contexto global, que exige uma maneira diferente de pensar e de agir. Nesta conjuntura, a atividade aquícola representada pelos produtores e empreendedores, fábricas de rações, agências regulatórias, e instituições de ensino e pesquisa podem definir códigos de conduta e práticas de manejo ambientalmente responsáveis de forma a minimizar os impactos ambientais da produção animal. Diante desta problemática, o objetivo deste trabalho consistiu na realização de dois experimentos com o intuito de auxiliar na determinação do impacto ambiental do fósforo total em rações para juvenis de tilápia do Nilo (Oreochromis niloticus) no ambiente aquático. Neste contexto, o primeiro experimento aborda a influência que a utilização de diferentes níveis de fósforo total na dieta possa promover devido à emissão de efluentes oriundos do cultivo de peixes. Utilizaram-se 120 juvenis de O. niloticus com 85,11 ± 0,34 g, com níveis de 0,8 e 1,2% de fósforo total na dieta para a determinação do coeficiente de digestibilidade aparente do fósforo em tilápias, aplicando-se como indicador o óxido crômico (Cr2O3) incorporado na proporção de 0,1% nas dietas. Posteriormente, para verificar a diferença que há no aproveitamento dos diferentes ingredientes utilizados na dieta para atender as exigências de fósforo total para tilápias e consequentemente na geração de efluentes, realizou-se um experimento, onde avaliaram-se a digestibilidade do fósforo total das rações, a estabilidade dos pélets de ração na água, a lixiviação dos minerais da ração durante sua exposição na água e a quantificação de efluentes gerados para produção de uma tonelada de tilápia. Para tanto, formularam-se seis rações isoprotéicas e isoenergéticas contendo 28% de proteína bruta e 3000 kcal de ED/kg com níveis de 0,8% de fósforo total, utilizando como ingredientes o fosfato bicálcico, farinha de carne e ossos, farinha de vísceras de aves, farinha de anchovas, farinha de resíduos de tilápia e farinha de ossos calcinada. Conclui-se que a utilização da dieta com disponibilidade de 0,8% de fósforo total promove o melhor controle da qualidade da água e pode ser utilizada como estratégia nutricional para diminuição de efluentes da aquicultura. Em relação aos ingredientes, a melhor eficiência na utilização do fósforo total foi de 83,74% para o fosfato bicálcico, 77,73% para a farinha de anchova, 75,27% para a farinha de tilápia e 73,42% para farinha de vísceras de aves em rações para juvenis de tilápias do Nilo. Portanto, por meio da nutrição animal é possível minimizar a excreção de metabolitos ao meio aquático proporcionando uma produção com menor impacto ambiental.

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Blandón, Nury Alexandra Muñoz [UNESP]. "Recuperação de níquel e outros metais a partir de diferentes fontes (rejeitos minerais de processo industrial e pentlandita '(Ni,Fe)IND. 9' 'S IND. 8' ) mediante lixiviação ácida e bacteriana." Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/100745.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Uma possibilidade para a recuperação de metais a partir de minerais com baixos teores ou de rejeitos industriais é a utilização da lixiviação com micro-organismos. A biolixiviação é o processo de oxidação bacteriana de sulfetos metálicos contendo metais de valor (por exemplo, níquel, cobre ou zinco), os quais são liberados para a solução, seguida da recuperação por técnicas metalúrgicas convencionais. Estudos de biolixiviação de concentrados de sulfetos minerais em tanques agitados e, sobretudo em pilhas, têm sido desenvolvidos em escala piloto e comercial. Entretanto, poucos trabalhos têm sido realizados sobre o aproveitamento de rejeitos minerais de processos convencionais, tais como flotação ou fusão em forno “flash”, por rotas biotecnológicas. O objetivo deste trabalho foi recuperar níquel e cobre de rejeitos industriais, provenientes de processo de flotação e de fusão, utilizando bactérias, especialmente da espécie Acidithiobacillus ferrooxidans ou pelo uso de soluções ácidas, em escala de laboratório. Também foram realizados experimentos de biolixiviação de um sulfeto de níquel (pentlandita) para avaliar o processo de solubilização do metal. Conjuntamente, outros experimentos foram realizados com a finalidade de se obter novas linhagens isoladas a partir destes rejeitos minerais. Suas diferenças fisiológicas foram avaliadas. A partir dos experimentos com os rejeitos encontrou-se que com a escória foi possível obter 13% de níquel e 8 % de cobre em solução após 14 dias de lixiviação biológica. Com soluções ácidas, em pH 0,5 e 1,0, as recuperações foram de 56% de níquel e 24% de cobre em pH 0,5 enquanto que em pH 1,0 as concentrações foram de 21% e 12% de niquele e cobre, respectivamente. Para a recuperação de níquel e cobre deste rejeito sugere-se a lixiviação ácida e não bacteriana. Com a lama as porcentagens...
Bacterial leaching is a feasible to recover metals from minerals with low grade or from mine wastes using microorganisms. The bioleaching process is the bacterial oxidation of valuables metals bearing sulphide minerals (e.g. nickel, copper or zinc), which are released to the solution, followed by conventional recovered by metallurgical techniques. Studies on bioleaching of sulphide minerals concentrates in stirred tanks and, particularly, in heaps, have been developed on pilot and commercial scales. However, few studies have been undertaken on using of mineral wastes from conventional processes such as flotation or flashing smelting through biotechnological routes. This work aims at recovering nickel and copper from industrial wastes such as flotation tailings and slag using bacteria, especially Acidithiobacillus ferrooxidans species, or using acid solutions at laboratory scale. Experiments were also accomplished for nickel sulfide bioleaching to evaluate the metal dissolution process, for comparison purpose. Other experiments were also carried out to obtain new strains isolated from mineral waste to study the physiological differences between them. After 14 days of bioleaching of slag it was possible to extract 13% of nickel and 8% of copper in solution while with acid solutions the extractions were 56% of nickel and 24% of copper at pH 0.5 and 21% and 12% at pH 1.0, respectively. For the metals solubilization from the slag it is suggested the acid leaching instead of bioleaching. With the flotation tailings the recoveries of nickel and copper were 23% e 16% at pH 0.5 or 1.0 while after 14 days with bioleaching the concentrations in solution were 46 % and 17% for nickel and copper. These results show that the flotation tailings can be treated with biological leaching for a higher recovery of metals. The studies of nickel sulfide bioleaching with different bacterial species reached only... (Complete abstract click electronic access below)

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29

Suprayogo, Didik. "Testing the safety-net hypothesis in hedgerow intercropping : water balance and mineral N leaching in the humid tropics." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326060.

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30

Blandón, Nury Alexandra Muñoz. "Recuperação de níquel e outros metais a partir de diferentes fontes (rejeitos minerais de processo industrial e pentlandita '(Ni,Fe)IND. 9' 'S IND. 8' ) mediante lixiviação ácida e bacteriana /." Araraquara : [s.n.], 2010. http://hdl.handle.net/11449/100745.

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Resumo: Uma possibilidade para a recuperação de metais a partir de minerais com baixos teores ou de rejeitos industriais é a utilização da lixiviação com micro-organismos. A biolixiviação é o processo de oxidação bacteriana de sulfetos metálicos contendo metais de valor (por exemplo, níquel, cobre ou zinco), os quais são liberados para a solução, seguida da recuperação por técnicas metalúrgicas convencionais. Estudos de biolixiviação de concentrados de sulfetos minerais em tanques agitados e, sobretudo em pilhas, têm sido desenvolvidos em escala piloto e comercial. Entretanto, poucos trabalhos têm sido realizados sobre o aproveitamento de rejeitos minerais de processos convencionais, tais como flotação ou fusão em forno "flash", por rotas biotecnológicas. O objetivo deste trabalho foi recuperar níquel e cobre de rejeitos industriais, provenientes de processo de flotação e de fusão, utilizando bactérias, especialmente da espécie Acidithiobacillus ferrooxidans ou pelo uso de soluções ácidas, em escala de laboratório. Também foram realizados experimentos de biolixiviação de um sulfeto de níquel (pentlandita) para avaliar o processo de solubilização do metal. Conjuntamente, outros experimentos foram realizados com a finalidade de se obter novas linhagens isoladas a partir destes rejeitos minerais. Suas diferenças fisiológicas foram avaliadas. A partir dos experimentos com os rejeitos encontrou-se que com a escória foi possível obter 13% de níquel e 8 % de cobre em solução após 14 dias de lixiviação biológica. Com soluções ácidas, em pH 0,5 e 1,0, as recuperações foram de 56% de níquel e 24% de cobre em pH 0,5 enquanto que em pH 1,0 as concentrações foram de 21% e 12% de niquele e cobre, respectivamente. Para a recuperação de níquel e cobre deste rejeito sugere-se a lixiviação ácida e não bacteriana. Com a lama as porcentagens... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Bacterial leaching is a feasible to recover metals from minerals with low grade or from mine wastes using microorganisms. The bioleaching process is the bacterial oxidation of valuables metals bearing sulphide minerals (e.g. nickel, copper or zinc), which are released to the solution, followed by conventional recovered by metallurgical techniques. Studies on bioleaching of sulphide minerals concentrates in stirred tanks and, particularly, in heaps, have been developed on pilot and commercial scales. However, few studies have been undertaken on using of mineral wastes from conventional processes such as flotation or flashing smelting through biotechnological routes. This work aims at recovering nickel and copper from industrial wastes such as flotation tailings and slag using bacteria, especially Acidithiobacillus ferrooxidans species, or using acid solutions at laboratory scale. Experiments were also accomplished for nickel sulfide bioleaching to evaluate the metal dissolution process, for comparison purpose. Other experiments were also carried out to obtain new strains isolated from mineral waste to study the physiological differences between them. After 14 days of bioleaching of slag it was possible to extract 13% of nickel and 8% of copper in solution while with acid solutions the extractions were 56% of nickel and 24% of copper at pH 0.5 and 21% and 12% at pH 1.0, respectively. For the metals solubilization from the slag it is suggested the acid leaching instead of bioleaching. With the flotation tailings the recoveries of nickel and copper were 23% e 16% at pH 0.5 or 1.0 while after 14 days with bioleaching the concentrations in solution were 46 % and 17% for nickel and copper. These results show that the flotation tailings can be treated with biological leaching for a higher recovery of metals. The studies of nickel sulfide bioleaching with different bacterial species reached only... (Complete abstract click electronic access below)
Orientador: Oswaldo Garcia Júnior
Coorientador: Denise Bevilaqua
Banca: Maria Lucia Gosales da Costa Araújo
Banca: Ana Teresa Lombardi
Banca: Wilson Cervi da Costa
Banca: Luis Gonzaga Santos Sobral
Doutor

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Khalesi, Mohammad Reza. "Integrated modeling of grinding, liberation and leaching of gold ores." Thesis, Université Laval, 2010. http://www.theses.ulaval.ca/2010/27466/27466.pdf.

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Togoro, Aluísio Hideki [UNESP]. "Uso do extrato pirolenhoso: Efeito no solo e nas plantas de tomate." Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/88222.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Foram conduzidos dois experimentos, sendo um deles com o objetivo de avaliar o efeito de concentrações de extrato pirolenhoso (EP) na movimentação de íons no perfil do solo e verificar as alterações nas propriedades químicas do mesmo, e o outro para verificar os efeitos do EP na nutrição, produção, classificação e características de sabor (sólidos solúveis total e acidez titulável) em plantas de tomateiro do grupo cereja, cultivados em ambiente protegido. No primeiro experimento, colunas desmontáveis foram preenchidas com Latossolo Vermelho e submetidas à aplicação de soluções com concentrações de EP (0, 1, 2, 4 e 8 % v/v) para avaliar 4 profundidades (0-10, 10-20, 20-30, 30-40 cm). Posteriormente foi realizada a lixiviação das colunas com aplicação de água deionizada na quantidade de uma vez e meia do volume de poros. Imediatamente após a lixiviação, tanto o lixiviado como o solo das diferentes profundidades foram coletados e analisados. A aplicação de 4 e 8% (v/v) de EP provocou diminuição no pH do solo nas camadas de 0-10 e 10-20cm com reflexo na lixiviação de K, Ca e Mg, além de aumento de Mn, Cu e Zn disponível no solo. O SO42- movimentou-se no solo independente da aplicação de EP, mas sua disponibilidade diminui com o aumento das concentrações de EP. A aplicação de 8% (v/v) de EP provocou diminuição de P nas camadas de 0-10 e 10-20cm com aumento na camada de 30-40cm e no lixiviado. No segundo experimento, plantas de tomateiro do grupo cereja foram cultivadas em solo tratado com 5 concentrações de EP (0; 1; 2; 4; 8% v/v), na presença e ausência de pulverização de EP (0,1% v/v) na parte aérea. Foram avaliados os atributos químicos do solo, acúmulo de massa seca da parte aérea, diâmetro de haste, área foliar, teor foliar e acúmulo de nutrientes da parte aérea e também distribuição dos...
Two experiments were carried out aiming to evaluate the effect of Pyroligneous Acid (PA) concentrations on the ions movement in the soil profile and it’s possible chemical properties changes, and also to evaluate the effect of PA on nutrition, production, classification and taste characteristics (total soluble solids and titratable acidity) on cherry tomato plants cultivated with PA in a greenhouse. The first experiment, columns were filled with Oxisol submitted to application of solution with PA concentrations (0,1, 2, 4 and 8% v/v), to evaluate four depths (0-10, 10-20, 20-30, 30-40 cm). Following, the columns were leached by application of deionized water at 1 ½ amount of its pores volume. Immediately after leaching, both the volume recovered as the soils recovered from different depths were collected and analyzed. The application of PA at 4 and 8% (v/v) promoted pH soil decrease at 0-10 and 10-20 cm layers reflecting on K, Ca, and Mg leaching, and an increase on Mn, Cu and Zn available in soil. The SO42- moved in the soil independently to PA application, however, its availability decreased with PA increasing concentrations. The application of 8% (v/v) PA promoted a decrease on P layers at 0-10 and 10-20 cm, but an increase on 30-40 and on the leached was observed. The second experiment, cherry tomato plants were cultivated in soil and treated with 5 PA concentrations (0, 1, 2, 4.8% v/v) and in the presence and absence of spraying 0.1% v/v PA on shoots. The soil chemical properties, shoots dry mass, stem diameter, leaf area, foliar nutrient accumulation content of aerial portion, fruit size distribution, fruits total numbers, fruits fresh mass, titratable acidity (TA) and total soluble solids (TSS) were evaluated. The PA application on soils of the ground up to a concentration of 2% (v/v) did not cause... (Complete abstract click electronic access below)

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Abdulmalek, Mohamed Milad. "Influence of landfill leachate on growth response and mineral content of Swiss chard." Thesis, Cape Peninisula University of Technology, 2014. http://hdl.handle.net/20.500.11838/2001.

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Thesis (MTech (Agriculture))--Cape Peninsula University of Technology, 2014.
In this study, laboratory and greenhouse experiments were conducted to evaluate the effects of utilization of land fill leachate for irrigation purposes on potted soil and Swiss chard, to provide more insight into effects of landfill leachates on the environment. Swiss chard was grown and irrigated with different concentrations of leachates in pot experiments. For several weeks, the experimental soil and Swiss chard leaves was analyzed to assess extent of change in different chemical compositions, post-irrigation. The leachate samples had a high electrical conductivity (mean = 383 mS cm-1) and high soluble salts content (mean values, Na = 714.5 mg/L, K= 56.8 mg/L, Ca = 133.7 mg/L, Mg = 68.8 mg/L, Cl = 983 mg/L); while the composition of heavy metals in these wastewater leachates were of low concentrations. The application of leachates in irrigation resulted in increased soil cation concentrations, particularly those of Na ions (increased sodicity). Similarly, an increase in electrical conductivity and pH were recorded in the soils after irrigation with leachates. The soil metal concentrations were low and there was no significant difference in soil heavy metal concentrations between the soils irrigated with leachate and those of the controls. The results also show significant (p <0.05) reduction (up to 50%) in Swiss chard growth with application of (100%, 50% and 25%) of leachate as source of irrigation water compared to the growth observed in leachate-free (control) irrigation systems. This reduction in growth was best attributed to the high cation content in plant tissue picked up from the soil which was high in cations as a result of leachate irrigation.

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Ghadiri, Mahdi. "Investigating variables affecting heap (bio)leaching through determining access to sub-surface mineral grains by micro-scale X-ray tomography." Master's thesis, Faculty of Engineering and the Built Environment, 2020. http://hdl.handle.net/11427/32424.

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Heap bioleaching is a hydrometallurgical technology, used to facilitate the extraction of valuable metals such as copper, gold, nickel and uranium from low-grade, typically sulphidic, ores. The process is highly complex as it is influenced by interactions of different sub-processes including flow of leaching solution around the ore particles, mass and heat transfer within and around the particles, chemical reactions, microbially-mediated reactions and microbial growth. Contact of leaching solution with mineral grains is necessary for oxidation of the sulphide minerals. However, a large fraction of the mineral grains is positioned below the surface of the ore particles and so contact with the liquid occurs through cracks and pores in the ore connected to the surface. Long extraction times and low metal recoveries typical of heap systems can be attributed to the slow leaching rate of these non-surface mineral grains as well as constraints on their accessibility. Most of the valuable grains that remain in the residue ores are non-surface grains. Therefore, investigation of the mechanism and behaviour of non-surface grain leaching and quantification of the factors contributing to their leaching is expected to be highly beneficial in the optimisation of leach conditions and recoveries. Non-surface grain leaching within large particles cannot be investigated via traditional experimental methods reliant on bulk measurements, 2D or destructive methodologies. However, it can be studied using high resolution, non-destructive 3D X-ray micro-Computed Tomography (μCT), an imaging technique for investigation of internal structure of opaque objects. X-ray μCT has previously been developed and used for investigation of different aspects of heap leaching. In the current study, the viability of using X-ray μCT to study heap bioleaching systems and affecting variables is assessed. This required establishment of procedures for measurement and analysis of sulphide and oxide mineral recoveries and leaching penetration distances. The feasibility of studying biotic heap leaching by X-ray μCT was explored through investigation of the relative energies required for high mineral resolution and avoidance of microbial inactivation. Specific bioleaching operating variables that were subsequently considered included: the accuracy and representivity of the X-ray μCT images, the influence of agglomeration pre-treatment, operating temperature, and type of ore on non-surface grain leaching. Addition of surfactants to the leaching solution was explored with the aim of changing surface activity to influence the penetration of the leach agent into pores and cracks in the ore. The effects of operating conditions on non-surface mineral grain leaching was studied using mini-column experiments. Three different low-grade ores, namely a chalcopyrite-rich ore, a malachite ore and a waste rock containing pyrite were prepared for the leaching experiment. The ores were crushed using a jaw crusher and comminuted down to 100% passing 16 mm. The products were sieved into six fractions (<0.25 mm, 0.25 - 1 mm, 1 - 2 mm, 2 - 5.6 mm, 5.6 - 8 mm, 8 - 16 mm) and each fraction then representatively split into smaller portions using a rotary splitter. One portion of each size fraction was taken for XRD, AAS and QEMSCAN analyses. Mini leaching columns were designed and constructed based on the target mineral grain distribution in the ores to ensure that the mineral grains were detectable using X-ray µCT, given its resolution limitations. The columns were charged with 50 g of agglomerated or non-agglomerated ore and lixiviant was provided at a flow rate of 2.55 mL h -1 for a period of 5.5 months for chalcopyrite and pyrite and 26 days for malachite in incubators at 30 °C, 37 °C and 65 °C. In order to select a surfactant suitable for use in a biological leach experiment, the effect of five different types and concentration of non-ionic surfactants on bioleaching microorganisms was studied in terms of microbial growth, ability for ferrous ion oxidation and chalcopyrite bioleaching. This was done in shake flask experiments using mineral concentrate. Based on the results of these experiments, Tween® 20 (10 mg L -1 ) was selected to study the effect of surfactant on non-surface mineral grain leaching in the mini-columns. Each column was scanned by X-ray μCT at 100 kV and 150 mA using a 0.38 mm copper filter and at a distance of 59.40 mm between X-ray gun and specimen. The advanced 3D analysis software Avizo® 9 was used to visualize and analyse image data. The Interactive Thresholding function in Avizo® 9 software was used for segmentation of ore particles from air and sulphide minerals from air and gangue minerals, to measure the target minerals' volume reduction during leaching. The Distance Map Algorithm was applied on a binary (segmented) image to calculate the distance of the sulphide mineral from the ore particle surface. Imaging of the whole mini-column was done before leaching and at the end of each experiment and imaging of certain sections was done at select time points during leaching to track temporal leaching dynamics. Good agreement was seen between the bulk mineral recovery data, determined using standard chemical assays, and the leaching curves generated using the X-ray µCT images for all the ores, confirming that the X-ray µCT images were a good quantitative measurement of the sulphide and oxide mineral leaching. Liquid microbial culture experiments were used to confirm that exposure to X-ray does not affect microbial activity for energy doses between 35 and 90 kV at 200-280 μA. However, X-ray exposure was found to have a slight negative influence at higher voltages of 120 and 150 kV, temporarily reducing the specific ferrous ion oxidation and suppressing the specific growth rate of the bioleaching microorganisms. The X-ray exposure thus negatively affected both the total microbial population available for leaching (population viability) as well as the metabolic activity of the individual microorganisms (population vitality). The effect of X-ray exposure on bioleaching cultures attached to a mineral surface was examined using pyrite-coated glass beads packed into mini-columns. The energy dosage limits identified in the liquid culture experiments were found to be compatible with the X-ray μCT imaging conditions (minimum energy dosage and sample position) required for acquisition of complete and accurate images of the columns at a resolution that allows identification of individual mineral grains. Following X-ray exposure, the performance of the exposed bioleaching mini-columns was equivalent to the unexposed control column. Similarly, the microbial activity and presence on the mineral surface appeared unchanged. Finally, the experiment was performed on the chalcopyrite ore and the microorganisms were found to still be able to convert Fe2+ to Fe3+ after 2 scanning runs. Thus, all sets of results confirm that X-ray μCT can be compatible with heap bioleaching experiments, while still permitting appropriate resolution of the mineral grains to make an X-ray μCT investigation worthwhile. However, cognisance that an upper limit of tolerable X-ray exposure exists must be taken. This may present a challenge if it is desired to image larger or denser ore samples which require a greater X-ray energy level for sufficient penetration of the sample by the X-rays and hence accurate imaging. In chalcopyrite leaching, increasing temperature from 37 °C to 65 °C resulted in clear enhancement of leaching based on both analysis methods, with the copper recovery increasing from 20% to 64% by the end of the leaching period, and the overall sulphide mineral dissolution increasing from 24% to 67%. Increasing temperature from 37 °C to 65 °C resulted in an increased leaching penetration distance and crack development in the particles, and thus an enhancement in copper recovery and sulphide mineral dissolution. This was in addition to the thermodynamically expected increased leaching rate. The maximum leaching penetration distance, beyond which no mineral volume change is observed, at 37 °C was 1.7 mm. This increased to 2.5 mm at 65 °C. As a result of addition of 10 mg L-1 Tween® 20 into the leaching solution, the final copper recovery was improved by 4% to 68% and the maximum penetration distance increased to 2.9 mm. However, when the availability of sulphide mineral was not rate limiting, the copper recovery and sulphide mineral volume reduction in the mini-column with surfactant was lower than the system without surfactant. This may have been due to depression of diffusion of ferric ion to the ore surface as a result of the formation of an adsorbed surfactant layer on the mineral surface. The performance with surfactant became superior as the amount of readily leachable mineral became limiting. In the pyrite waste rock, an increase in temperature did not have any effect on the maximum penetration distance and any increase in iron recovery was only for thermodynamic reasons. Similarly to the chalcopyrite ore, during the later period of leaching when readily exposed mineral grains have been depleted, the system performed better in the presence of surfactant. The addition of surfactant increased the maximum penetration distance from 2.7 to 2.9 mm. The cumulative copper recovery of 86% was obtained for malachite ore in 26 days of acid leaching and the maximum penetration distance was 2.2 mm. This study thus demonstrates the value of the X-ray µCT technique for quantitative investigation of non-surface mineral grain leaching and confirms that the maximum penetration distance can be affected with changing operation conditions or ore type. This study thus demonstrates the X-ray µCT technique for quantitative investigation of non-surface mineral grain bioleaching and confirms that the maximum penetration distance can be affected with changing operation conditions. Critically, the results confirm that X-ray μCT can be compatible with bioleaching microorganisms, while still permitting appropriate resolution of the mineral grains to make an X-ray μCT investigation worthwhile.

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35

Aydin, Gulsen. "Use Of Waste Pyrite From Mineral Processing Plants In Soil Remediation." Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613900/index.pdf.

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Pyrite (FeS2) is commonly present in complex sulphide ores in significant amounts. After the enrichment of such ores by flotation, pyrite is either produced as a separate concentrate and sold to acid manufactures or removed and disposed off as tailing. Due to lack of demand from manufacturers, most of pyrites is usually disposed off as tailing. Therefore, pyrite is usually a waste from complex sulphide ores. Yet, it may be a remediation additive for calcareous soils and calcareous- alkali soils deficient in Fe and other micronutrients such as Cu, Zn and Mn. Waste pyrite may be also an alternative amendment to gypsum because of the production of sulphuric acid which is effectively used in the reclamation of calcareous alkali soils. The effectiveness of adding waste pyrite and sulphuric acid produced from waste pyrite to calcareous-alkali soil (Saraykö
y-Ankara) and calcareous soil (Gaziantep) was studied under laboratory conditions. Pure gypsum was also used as an amendment for the comparison of the effectiveness of waste pyrite in the reclamation of alkali soils. Gypsum, powder waste pyrite and sulphuric acid were applied to the soil with reference to the gypsum requirement (GR) of the soils. Greenhouse pot tests were carried out with wheat as test plant to determine the effect of waste pyrite treatment on the plant yield (wheat) and on the amount of micronutrient (Fe, Cu, Zn, Mn) essential for plant growth. Hazard potential of pyritic tailings in terms of heavy metal contamination was also taken into account. The results showed that the soil pH and exchangeable sodium percentage (ESP), indicators of alkalization, decreased upon pyrite addition to calcareous- alkali soils of Saraykö
y-Ankara. It was also found that pyritic tailings were effective in the increasing level of essential micronutrients (Fe, Cu, Zn and Mn) for plant growth in both soils. This was ascertained by the dry matter yield of the plants in the green house pot tests. Heavy metal toxicity caused by pyrite which is a rightful concern remained well below the legal limits in the soils. Thus, it was concluded that the application of pyritic tailings promoted rapid amelioration of calcareous-alkali soil (Saraykö
y-Ankara) and calcareous soil (Gaziantep) with no deleterious heavy metal contamination.

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Herrmann, Daniela da Rocha. "Associação de água residuária da suinocultura e adubação mineral no cultivo de aveia-preta." Universidade Estadual do Oeste do Parana, 2013. http://tede.unioeste.br:8080/tede/handle/tede/685.

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Swine wastewater (SWW) has high organic load becoming an important source of macro and micronutrients to plants, promoting the improvement of soil quality and development in several tilth. however when done without agronomic and environmental standard, can cause problems in soil, leaching of nutrients, prejudice to water resources and toxicity to plants. The objective of this work, was to evaluate the chemical in soil and leachat regarding association of swine wastewater and mineral fertilization(MF) in farming black oat. Conducted an experiment using applications of SWW associated or not with MF, the treatments consisted of rates 0, 100, 200 and 300 m3ha-1 in the absence or presence MF, under field conditions. Were collected and analysis of soil and leachate in two seasons. It was observed effect associated with the wastewater and mineral fertilization on phosphorus in soil, isolated effect of mineral fertilization on the magnesium, potassium and electrical conductivity in soil and isolated effect of wastewater in the levels of pH, calcium, sodium, copper, zinc, nitrite + nitrate in soil and effect on sodium content in leachate
A água residuária da suinocultura (ARS) possui carga orgânica elevada se tornando fonte importante de macro e micronutrientes às plantas, promovendo a melhoria da qualidade do solo e do desenvolvimento em diversas culturas. Porém quando feita sem critérios agronômicos e ambientais, pode causar problemas no solo, lixiviação de nutrientes, prejuízos aos recursos hídricos e toxicidade às plantas. O objetivo deste trabalho foi avaliar os atributos químicos em solo e lixiviado frente a associação de água residuária da suinocultura e adubação mineral (AM) no cultivo de aveia-preta. Realizou-se um experimento em lisímetros de drenagem usando aplicações de ARS associadas ou não a AM, os tratamentos consistiram em doses de 0, 100, 200 e 300 m3ha-1 com ausência ou presença de AM, em condições de campo. Foram realizadas coletas e análises de solo e lixiviado em duas épocas. Observou-se efeito associado da água residuária e adubação mineral no teor de fósforo no solo, efeito isolado da adubação mineral nos teores de magnésio, potássio e condutividade elétrica no solo e efeito isolado da água residuária nos teores de pH, cálcio, sódio, cobre, zinco, nitrito + nitrato no solo e efeito no teor de sódio no lixiviado

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Togoro, Aluísio Hideki. "Uso do extrato pirolenhoso : Efeito no solo e nas plantas de tomate /." Jaboticabal : [s.n.], 2012. http://hdl.handle.net/11449/88222.

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Orientador: Jairo Osvaldo Cazetta
Banca: Arthur Bernardes Cecílio Filho
Banca: Adriano Bortolotti da Silva
Resumo: Foram conduzidos dois experimentos, sendo um deles com o objetivo de avaliar o efeito de concentrações de extrato pirolenhoso (EP) na movimentação de íons no perfil do solo e verificar as alterações nas propriedades químicas do mesmo, e o outro para verificar os efeitos do EP na nutrição, produção, classificação e características de sabor (sólidos solúveis total e acidez titulável) em plantas de tomateiro do grupo cereja, cultivados em ambiente protegido. No primeiro experimento, colunas desmontáveis foram preenchidas com Latossolo Vermelho e submetidas à aplicação de soluções com concentrações de EP (0, 1, 2, 4 e 8 % v/v) para avaliar 4 profundidades (0-10, 10-20, 20-30, 30-40 cm). Posteriormente foi realizada a lixiviação das colunas com aplicação de água deionizada na quantidade de uma vez e meia do volume de poros. Imediatamente após a lixiviação, tanto o lixiviado como o solo das diferentes profundidades foram coletados e analisados. A aplicação de 4 e 8% (v/v) de EP provocou diminuição no pH do solo nas camadas de 0-10 e 10-20cm com reflexo na lixiviação de K, Ca e Mg, além de aumento de Mn, Cu e Zn disponível no solo. O SO42- movimentou-se no solo independente da aplicação de EP, mas sua disponibilidade diminui com o aumento das concentrações de EP. A aplicação de 8% (v/v) de EP provocou diminuição de P nas camadas de 0-10 e 10-20cm com aumento na camada de 30-40cm e no lixiviado. No segundo experimento, plantas de tomateiro do grupo cereja foram cultivadas em solo tratado com 5 concentrações de EP (0; 1; 2; 4; 8% v/v), na presença e ausência de pulverização de EP (0,1% v/v) na parte aérea. Foram avaliados os atributos químicos do solo, acúmulo de massa seca da parte aérea, diâmetro de haste, área foliar, teor foliar e acúmulo de nutrientes da parte aérea e também distribuição dos... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Two experiments were carried out aiming to evaluate the effect of Pyroligneous Acid (PA) concentrations on the ions movement in the soil profile and it's possible chemical properties changes, and also to evaluate the effect of PA on nutrition, production, classification and taste characteristics (total soluble solids and titratable acidity) on cherry tomato plants cultivated with PA in a greenhouse. The first experiment, columns were filled with Oxisol submitted to application of solution with PA concentrations (0,1, 2, 4 and 8% v/v), to evaluate four depths (0-10, 10-20, 20-30, 30-40 cm). Following, the columns were leached by application of deionized water at 1 ½ amount of its pores volume. Immediately after leaching, both the volume recovered as the soils recovered from different depths were collected and analyzed. The application of PA at 4 and 8% (v/v) promoted pH soil decrease at 0-10 and 10-20 cm layers reflecting on K, Ca, and Mg leaching, and an increase on Mn, Cu and Zn available in soil. The SO42- moved in the soil independently to PA application, however, its availability decreased with PA increasing concentrations. The application of 8% (v/v) PA promoted a decrease on P layers at 0-10 and 10-20 cm, but an increase on 30-40 and on the leached was observed. The second experiment, cherry tomato plants were cultivated in soil and treated with 5 PA concentrations (0, 1, 2, 4.8% v/v) and in the presence and absence of spraying 0.1% v/v PA on shoots. The soil chemical properties, shoots dry mass, stem diameter, leaf area, foliar nutrient accumulation content of aerial portion, fruit size distribution, fruits total numbers, fruits fresh mass, titratable acidity (TA) and total soluble solids (TSS) were evaluated. The PA application on soils of the ground up to a concentration of 2% (v/v) did not cause... (Complete abstract click electronic access below)
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Rampim, Leandro. "Atributos químicos de um latossolo vermelho eutroférrico submetido a gessagem e cultivado com trigo e soja em semeadura direta." Universidade Estadual do Oeste do Paraná, 2008. http://tede.unioeste.br:8080/tede/handle/tede/1333.

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Fundação Araucária
The presence of aluminum in the soil is one among the several existent problems that harm the growth, development and productivity in commercial cultures as soy and wheat principally when water deficit, once there is minor surface of roots for the absorption of water. Like this the influence of the use of the plaster was analyzed in the chemical characteristics of a Latossolo vermelho eutroférrico of loamy texture for the wheat cultures and soy, under system of direct planting. It took place collections of soil samples to the six and 12 months after application 0, 1, 2, 3, 4 e 5 t ha-1 of the gypsum to evaluate the tenors of Ca, Mg, K, exchangeable Al, pH, SB, V%, m% and tenor of S in the soil. For the wheat cultures and soy they were appraised the tenors of Ca, Mg, K, S, and Al in the tissue, mass of 1000 grains and productivity. The use of gypsum increased the tenors of Ca and S and it reduced Al's tenors, besides leaching Mg and K in the soil, increasing SB and V% in the deepest layers. In the tissue increased Ca and Mg for the soy and it reduced in the wheat, it increased the tenor of S in both cultures and K increased in a quadratic way for the culture of the soy. The found results show that the use of the plaster provided mobility of K+ and Mg2+ up to 40 cm of depth. The use of up to 5 t ha-1 of gypsum they resulted in increase of the tenors of Ca2+ and SO42 - in depth until one year after the application and the dose of 3 t ha-1 it provided larger reduction of exchangeable Al and also of the saturation for Al for Latossolo vermelho eutroférrico of loamy texture. In exchangeable Al's presence the use of the gypsum implicated in increase of the wheat productivity but it didn't influence the productivity of the soy
A presença de alumínio no solo é um entre os diversos fatores existentes que prejudicam o crescimento, desenvolvimento e produtividade de culturas comerciais como soja e trigo principalmente quando ocorre déficit hídrico, uma vez que há menor superfície de raízes para a absorção de água e nutrientes. Este trabalho avaliou a influência do uso do gesso nas características químicas de um Latossolo Vermelho eutroférrico de textura argilosa para as culturas de trigo e soja, sob sistema de plantio direto. Realizou-se coletas de amostras de solo aos seis e 12 meses após aplicação superficial de 0, 1, 2, 3, 4 e t ha-1 de gesso para avaliar os teores de Ca, Mg, K, Al trocáveis, pH, SB, V%, m% e teor de S no solo. Para as culturas de trigo e soja foram avaliados os teores de Ca, Mg, K, S, e Al no tecido foliar, massa de 1000 grãos e produtividade. O uso de gesso aumentou os teores de Ca e S e reduziu os teores de Al, além de lixiviar Mg e K no solo, aumentando a SB e V% nas camadas mais profundas. No tecido foliar aumentou Ca e Mg para a soja e reduziu no trigo, aumentou o teor de S em ambas culturas e o K aumentou de forma quadrática para a cultura da soja. Os resultados encontrados mostram que o uso do gesso proporcionou mobilidade de K+ e Mg2+ até 40 cm de profundidade. O uso de até 5000 kg ha-1 de gesso resultaram em aumento dos teores de Ca2+ e SO42- em profundidade até um ano após a aplicação sendo que a dose de 3 t ha-1 proporcionou maior redução do Al trocável e também da saturação por Al para o Latossolo Vermelho eutroférrico de textura argilosa. Na presença de Al trocável o uso do gesso implicou em aumento da produtividade de trigo mas não influenciou a produtividade da soja

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Kessler, Nathalie Caroline Hirt. "Água residuária de suinocultura associada à adubação mineral em culturas de milho, aveia e soja." Universidade Estadual do Oeste do Parana, 2012. http://tede.unioeste.br:8080/tede/handle/tede/400.

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This study aimed at evaluating the agronomic and environmental aspects as results from the continuing application of swine wastewater and mineral fertilizer in corn, black oats and soybeans. The experimental area has a history of swine wastewater application with trials that have been carried out since 2006, whose cycles under management are the seventh, eighth and ninth ones. Four doses of swine wastewater associated with the presence and absence of mineral fertilizer consisted on eight treatments applied to experimental plots. The agronomic and nutritional indices were determined in the three studied crops. The compounds of leachate collected at the beginning and end of each cycle were also recorded as well as soil characteristics at the beginning and end of each crop. The experimental design was in randomized blocks, under a 4x 2 factorial scheme with three replications. The results were submitted to ANOVA and means compared by Tukey test at 5% significance level. In maize crop, after a swine wastewater application, treated in digester, it could be observed that it could be partially used as an alternative fertilizer, since P and Mn+2 were supplemented with specific fertilization. A special management should be given to the accumulation of Fe+2, Cu+2 and Zn+2 in soil. Attention should be paid also to the levels of Cu+2, Fe+2, Mn+2, NO3-+NO2-, Na+ and Zn+2 in leachate material. In black oats crop, after two applications of swine wastewater treated in digester, it was concluded that swine wastewater can be partially used as an alternative fertilizer, since N, P and S could be supplied. Some attention should be taken with Cu+2 and Zn+2 accumulation in soil and some special care should also be given to the leaching of Cu+2, Fe+2, Mn+2, NO3-+NO2-, Na+ and Zn+2. In soybean crop, after three applications of wastewater treated in digester, the remaining wastewater could be partially used as an alternative fertilizer, since N, P, K+ and S were supplied by specific fertilization. There must have extra attention to the accumulation of Fe+2, Cu+2 and Zn+2 in soil as well as to percolation of Cu+2, Fe+2, Mn+2, NO3-+NO2-, Na+ and Zn+2 According to leachate.
O presente trabalho teve como objetivo avaliar os aspectos ambientais e agronômicos decorrentes da aplicação continuada de água residuária da suinocultura e adubação mineral, nas culturas de milho, aveia e soja. A área experimental possui histórico de aplicação de água residuária da suinocultura, com experimentos conduzidos desde 2006, os quais são o sétimo, oitavo e nono ciclos conduzidos na área. Quatro doses de água residuária da suinocultura, associadas à ausência e presença de adubação mineral, consistiram em oito tratamentos aplicados às parcelas experimentais. Foram determinados índices agronômicos e nutricionais nas três culturas, avaliadas as composições dos lixiviados coletados no início e final de cada ciclo, bem como as características químicas do solo ao início e final de cada cultura. O delineamento experimental consistiu de blocos casualizados em esquema fatorial (4x2) com três repetições. Os resultados obtidos foram submetidos à análise de variância e as médias comparadas pelo teste de Tukey a 5% de significância. Na cultura do milho, após uma aplicação de água residuária da suinocultura tratada em biodigestor, verifica-se que a água residuária da suinocultura pode ser parcialmente utilizada como fertilizante alternativo, desde que o P e Mn+2 sejam complementados com adubação específica. Cuidado especial deve ser dado ao acúmulo de Fe+2, Cu+2 e Zn+2 no solo. Devem-se atentar também para os níveis de Cu+2, Fe+2, Mn+2, NO3-+NO2-, Na+ e Zn+2 no material percolado. Na cultura da aveia, após duas aplicações de água residuária de suinocultura tratada em biodigestor, conclui-se que essa pode ser parcialmente utilizada como fertilizante alternativo, desde que o N, P e S sejam complementados. Deve-se ter atenção com o acúmulo de Cu+2 e Zn+2 no solo, e com a lixiviação de Cu+2, Fe+2, Mn+2, NO3-+NO2-, Na+ e Zn+2. Na cultura da soja, após três aplicações de água residuária de suinocultura tratada em biodigestor, constata-se que a mesma pode ser parcialmente utilizada como fertilizante alternativo, desde que o N, P, K+ e S sejam complementados com adubação específica. Deve-se ter atenção com o acúmulo de Fe+2, Cu+2 e Zn+2 no solo. Deve ser dada maior atenção à percolação de Cu+2, Fe+2, Mn+2, NO3-+NO2-, Na+ e Zn+2 de acordo com o lixiviado

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Hoummady, Emerence. "Étude multi-échelle de l’agglomération pour la lixiviation en tas de minerais uranifères." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0271/document.

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La lixiviation en tas est une méthode industrielle utilisée pour traiter des minerais à basse teneur consistant en la percolation d’une solution de lixiviation à travers un tas de 6 à 9 mètres de haut afin d’en extraire l’élément d’intérêt. Cependant, la présence de nombreuses fines particules et d’argiles au sein du minerai peuvent causer l’apparition de phénomènes de colmatage dans les tas, diminuant l’efficacité de la lixiviation. Afin de résoudre ce problème, les industries du nickel, du cuivre ou encore de l’uranium agglomèrent le minerai, augmentant ainsi sa granulométrie par le rassemblement des fines particules. Néanmoins, l’agglomération de minerais uranifères ainsi que l’impact de la structure des agglomérats sur la lixiviation reste peu étudiée. Cette thèse a permis de caractériser l’évolution structurale et pétro physique des agglomérats de minerais d’uranium au cours de la lixiviation, d’étudier l’influence des conditions d’agglomération sur la structure des agglomérats résultants et enfin d’étudier la lixiviation des agglomérats à l’échelle du tas, par le biais d’essais en colonnes métriques. De plus, les causes de colmatage ont pu être identifiées comme provenant d’une dégradation mécanique des agglomérats entrainant une réduction de la perméabilité et de la porosité du tas
Heap leaching allows processing low grade ores. Basically, this industrial mining process consists in percolating a leaching solution slowly down through an ore heap of 6 to 9 meters high to extract the metals of interest. However, fine particles and clays are often the cause of clogging within heaps, leading to a decrease of leaching efficiency. To solve this problem, copper, nickel and uranium industry uses agglomeration of the ore particles. This process allows adjusting the particle size distribution by gathering fine particles. However uranium-ore agglomeration and the impact of the agglomerates structure on heap leaching remains poorly understood. The current thesis allowed characterizing structural and petrophysical properties of agglomerates and its evolution during leaching, studying the influence of agglomeration conditions on agglomerates structures and finally upscaling there results at the heap scale, using meter scale columns. Clogging phenomena were especially due to the mechanical degradation of agglomerates, causing a decrease of both heap porosity and permeability

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Golela, Mhlangabezi Tolbert. "Effect of microbial consortium on the biokinetic test for assessing acid rock drainage potential." Thesis, Cape Peninsula University of Technology, 2018. http://hdl.handle.net/20.500.11838/2754.

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Thesis (Master of Engineering in Chemical Engineering)--Cape Peninsula University of Technology, 2018.
Acid rock drainage (ARD) is one of the most severe environmental challenges currently faced by the mining industry worldwide. ARD is formed from the oxidation of sulphide-bearing minerals, particularly pyrite, in the presence of water and oxygen. ARD generation is accelerated by the presence of naturally occurring iron and sulphur-oxidizing micro-organisms, which regenerate leaching agents that facilitate sulphide mineral oxidation. ARD pollution is characterized by a high concentration of metals and sulphates in solution, low pH and a high salt content (salinity) in the environment, contaminating soil and groundwater. In South Africa, ARD is a major challenge in the gold and coal mining industries, where millions of tons of sulphide waste rock and overburden are generated and discarded. Characterization of these waste materials is required to develop an appropriate disposal strategy to minimise the risk of pollution and the generation of ARD. Potential ARD generation prediction from waste rock depends on the precise characterization of ARD potential using Biokinetic tests. Commonly used ARD prediction methods are static and long-term kinetic tests. Static tests provide data for a worst-case scenario focussing on strong acid chemical leaching potential to give an overall acid forming potential of a sample. Such kinetic tests provide data illustrating the rate of the net acid generation capacity of mine waste. However, these tests are capital intensive and time-consuming and fail to provide adequate information on the effect of micro-organisms on the overall net acid generation capacity of mine waste. The Biokinetic test reported herein and developed at the University of Cape Town, focusses on addressing a worst case scenario provided by static tests in a cost-effective manner and reduced time frames provided for by conventional kinetic tests. This test primarily provides relative rates of ARD generation in the presence of micro-organisms within 90 days. However, the Biokinetic test is at the developmental stage and thus far, has not been consistently used for different waste ores to determine a standardised approach. Therefore, the aim of this study was to investigate the effects of microbial consortia and to develop a standardisation approach for the test for ARD formation potential using gold-bearing and copper-bearing waste rock. Additionally, to refine the Semi-continuous Biokinetic test simulation, a flow-through system where there is minimal seepage in the waste deposit, was also developed. The sulphur content of the gold and copper-bearing samples used in this study was between 2.3 and 3.15%, respectively. These waste rock samples were found to be potentially acid- forming. In the Biokinetic test, finely milled waste rock samples were slurrified, inoculated with consortia and cultured under standard bioleaching conditions. Leaching and acidification rates were monitored.

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Feynerol, Vincent. "Traitement de minerais de fer par lixiviation alcaline suivi de leur électrolyse en milieu alcalin." Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0163.

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Un procédé innovant de production de fer par électrolyse d’une suspension d’oxydes de fer en milieu alcalin concentré est développé au centre de recherche d’ArcelorMittal de Maizières-lès-Metz. Ce procédé s’il atteignait la maturité industrielle permettrait de réduire significativement les émissions de dioxyde de carbone associées à l’industrie sidérurgique, en remplaçant le carbone utilisé comme agent réducteur dans les hauts-fourneaux par de l’électricité. Bien que ce procédé permette la production de fer à partir d’hématite commerciale (Fe2O3) à une densité de courant de l’ordre de 1000 A.m-2 avec une efficacité faradique supérieure à 80%, une dégradation des performances est systématiquement constatée lors de l’électrolyse de minerais de fer. Les impuretés majoritaires de ces minerais sont les oxydes et hydroxydes d’aluminium et de silicium, des composés solubles dans la soude concentrée. Ces composés pourraient donc être à l’origine de la baisse de réactivité observée lors de l’alimentation du procédé par des minerais de fer. Ainsi afin de tenter d’améliorer les performances de l’électrolyse alcaline à partir de minerais, des traitements de lixiviation alcaline sur un minerai défini ont été effectués dans cette thèse. La réactivité des minerais avant et après traitement a été comparée par chronoampérométrie. Bien que suite à l’élimination de ses composés alumineux, le minerai traité ait vu son rendement faradique réhaussé à environ 80% pour une valeur avant pré-traitement de 65%, sa densité de courant est restée deux fois moins élevée que celle de l’hématite pour une même tension électrique appliquée. Des expériences d’ajout d’ions aluminates et d’ions silicates lors de l’électrolyse d’hématite pure n’ont de plus eu pratiquement aucun effet indésirable sur son électrolyse. Les diverses expériences conduites dans cette thèse laissent supposer que les impuretés traitées n’ont que peu d’influence sur la réactivité des minerais. Le procédé est en revanche très sensible à la granulométrie des particules de minerais. Par ailleurs de forts phénomènes d’agglomération, qui n’ont pas lieu avec les oxydes de fer purs, ont été constatés lors de mesure de granulométrie du minerai étudié. Ainsi les expériences réalisées laissent supposer qu’un autre phénomène, probablement lié à la granulométrie secondaire des minerais en milieu alcalin concentré, soit à l’origine de la baisse de réactivité observée lors de leur électrolyse. Parallèlement une analyse thermodynamique avancée a été menée afin de déterminer les meilleures conditions théoriques de pression, de température et de concentration en NaOH pour effectuer l’électrolyse de l’hématite. La solubilité des composés de la gangue a été représentée avec des équations de Pitzer, et de nouveaux paramètres ont été calculés pour les interactions Na-SiO3-Al(OH)4. Cette étude thermodynamique a permis la conception et le pré-dimensionnement d’une étape de traitement des minerais par lixiviation alcaline
An innovative ironmaking process by alkaline electrolysis of suspended iron oxides is being developed at ArcelorMittal Global R&D Maizières-lès-Metz. Were it to achieve industrial maturity, this process would permit a significant reduction of steelmaking CO2 emissions. Indeed, the use of carbon as a reducing agent in blast furnace would be replaced by electricity. Although this process enables iron production from commercial hematite (Fe2O3) at current density of 1000 A.m-2 with faradaic efficiency higher than 80%, these performances are systematically lower when using iron ore instead. The main impurities in these ores are aluminium and silicon oxides and hydroxides, these compounds are soluble in concentrated sodium hydroxide solutions. These compounds could be the source of the decrease in reactivity observed when feeding the process with iron ores. To raise the electrolysis performance with iron ores, alkaline leaching treatments were conducted on a defined iron ore. Reactivity of iron ores before and after treatment was compared by chronoamperometry. Although the elimination of aluminous compounds resulted in the ore gaining a faradaic yield increase to a value of 80%, compared with 65% before treatment, its current density remained twice as low as the one of hematite for a same applied voltage. Furthermore, complementary experiments of aluminate and silicate ions addition during pure hematite electrolysis did not have any deleterious effect on its electrolysis. Based on all the experiments undertaken in this PhD, it seems unlikely that siliceous and aluminous impurities hold an important effect on iron ore reactivity in alkaline electrolysis. The process is nonetheless very sensitive to iron ores granulometry. On this subject, strong agglomeration phenomena were witnessed when measuring iron ores granulometry but did not occur with pure iron oxides. Therefore, it would seem that other phenomena may be the main cause of reactivity loss, these phenomena may well be linked to secondary granulometry of iron ores in concentrated alkaline media. In parallel, an advanced thermodynamic analysis was carried out to describe the best theoretical conditions for pressure, temperature and NaOH concentration to realize hematite electrolysis. Gangue compounds solubility was represented with Pitzer equations, and new parameters were calculated for Na-SiO3-Al(OH)4 interactions. This thermodynamic study enabled the design and pre-sizing of a treatment step for iron ores by alkaline leaching

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Ivanaj, Silvester. "Rôle de l'électrochimie au cours de la dissolution sélective des minerais et/ou des concentrés de chalcopyrite." Vandoeuvre-les-Nancy, INPL, 1995. http://docnum.univ-lorraine.fr/public/INPL_T_1995_IVANAJ_S.pdf.

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Les schémas actuels de traitement des minerais et des concentrés de chalcopyrite aboutissent à la formation du SO2 dont le rejet partiel ou complet dans l'atmosphère pose des problèmes pour l'environnement. Suite aux nouvelles réglementations sur l'environnement et à la pression de l'opinion publique, de nombreuses recherches se poursuivent afin de trouver d'autres alternatives qui auraient l'avantage de produire le soufre élémentaire. Dans ce contexte, cette étude porte sur la dissolution électrochimique sélective de la chalcopyrite à partir d'un minerai naturel et d'un concentré de flottation. Différents types de réacteurs électrochimiques et notamment un réacteur à lit granulaire E3P, une cellule à diaphragme poreux et une cellule à membrane échangeuse d'ions ont été testés. Des techniques de caractérisation physico-chimique telles que la DRX, le MEB, la Microscopie Optique, la Spectroscopie Raman, l'Analyse chimique, etc. , ont été utilisées pour caractériser les échantillons initiaux et les produits des réactions chimiques et/ou électrochimiques. L’oxydation du minerai dans le réacteur E3P permet une dissolution préférentielle des composés du fer autres que la chalcopyrite, tandis que la réduction favorise la solubilisation du fer de la chalcopyrite. Cependant, dans les deux cas, la cinétique est lente et le rendement faradique est faible. L’utilisation de la cellule à diaphragme poreux n'a pas sensiblement amélioré les résultats de la dissolution. Les meilleurs résultats ont été obtenus en utilisant la cellule électrochimique à membrane échangeuses d'ions. La dissolution de la chalcopyrite est essentiellement réalisée par les ions ferriques et cuivriques générés électrochimiquement in-situ. Un taux d'extraction de cuivre atteignant 98% a été obtenu. Dans les conditions optimales, les rendements faradiques sont proches de 100%. La chalcopyrite est dissoute sélectivement et la majorité du soufre est obtenue sous forme élémentaire

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Villetti, Pedro Ivo Chitolina. "Produção de coagulante férrico a partir da lixiviação de concentrado de pirita da mineração de carvão via cristalização/solubilização de sulfato ferroso : estudo comparativo entre rejeitos de duas jazidas." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/174405.

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O beneficiamento de carvão mineral para a utilização em termoelétricas gera grandes quantida-des de rejeitos, os quais contêm diversos minerais, entre eles a pirita (sulfeto de ferro - FeS2). A pirita, na presença de água e oxigênio se oxida, gerando a drenagem ácida de minas (DAM), principal fonte de contaminação dos aquíferos e do solo nas regiões carboníferas. Atualmente, a DAM é tratada pelo método de neutralização/precipitação de metais. Essa é uma técnica con-siderada “fim-de-tubo” com diversas desvantagens, entre elas o alto custo. Entretanto, através de técnicas preventivas, baseadas nos princípios da produção mais limpa, é possível, concomi-tantemente, minimizar a geração de DAM e agregar valor à parte ou totalidade dos rejeitos de carvão. Assim, o objetivo deste trabalho foi estudar a produção do coagulante sulfato férrico a partir da lixiviação de um concentrado de pirita oriundo de rejeitos de carvão via cristaliza-ção/solubilização de sulfato ferroso, comparando o processo para duas jazidas distintas de car-vão mineral. Amostras de concentrados de pirita foram obtidas de rejeitos de carvão das jazidas do Estado de Santa Catarina, minerados na cidade de Forquilhinha, e do Estado do Paraná, na cidade de Figueira A parte experimental foi realizada a partir de um reator de leito empacotado em planta-piloto e envolveu as seguintes etapas: produção de um lixiviado férrico, conversão do lixiviado férrico em ferroso, precipitação do Fe2+ e do sulfato na forma de cristais de sulfato ferroso heptahidratado com auxílio de etanol. Estudou-se, de forma detalhada, a proporção li-xiviado:etanol para o melhor rendimento do processo. Os cristais de sulfato ferroso produzidos a partir do concentrado de pirita catarinense apresentaram características semelhantes a um pa-drão analítico (menos de 1% de impurezas). Os cristais produzidos a partir da pirita paranaense apresentaram um índice levemente superior ao padrão estabelecido comercialmente (1,08%), além de apresentar alguns metais bastante perigosos à saúde, como arsênio. Também se estudou a produção do coagulante férrico via dissolução dos cristais de sulfato ferroso e oxidação do ferro pela adição de soluções aquosas com agentes ácidos e oxidantes. A melhor condição ob-tida foi a seguinte: 5 g de sulfato ferroso, 7,5 mL de água destilada, 1,5 mL de peróxido de hidrogênio e 5 gotas de ácido sulfúrico. Essa proporção proporcionou um coagulante com quase 12% de ferro, sendo que 97% deste ferro na forma férrica. O coagulante produzido foi utilizado no tratamento de água do corpo hídrico Guaíba, empregando-se como referência os padrões brasileiros de potabilidade (Portaria nº 2914 do Ministério da Saúde). Mostrando-se eficiente no tratamento de água para fins de abastecimento público.
The coal processing for use in power plants, generates amounts of residues, which contain var-ious minerals, such as pyrite (iron sulfide-FeS2). Pyrite, in the presence of water and oxygen, oxidizes, generating acid mine drainage (AMD), the main source of contamination of aquifers and soil in the carboniferous region of Santa Catarina. Currently, the AMD is treated by the method of neutralization/precipitation of metals. This is a technique considered "end-of-pipe" with many disadvantages, like the excessive cost. However, through preventive techniques, based on the principles of cleaner production, it is possible, at the same time, minimize the generation of AMD and to add value to a part or totality of coal waste. Thus, the objective of this work was to study the production of ferric sulphate coagulant from the leaching of a pyrite concentrate from coal tailings via crystallization / solubilization of ferrous sulphate, comparing the process to two distinct mineral coal deposits. Samples of pyrite concentrates were obtained from coal tailings from the State of Santa Catarina mines, mined in the city of Forquilhinha, and from the State of Paraná, in the city of Figueira The experimental part was carried out in a bed reactor packed in a pilot plant and involved the following steps: production of a ferric leachate, conversion of ferric leachate into ferrous, precipitation of Fe2 + and sulphate as crystals of ferrous sulphate heptahydrate. It was also studied, in detail, the proportion leached:ethanol for the best yield of the process. The ferrous sulphate crystals produced from the Santa Catarina pyrite concentrate showed characteristics similar to an analytical standard (less than 1% of im-purities). The crystals produced from the Paraná pyrite concentrate presented an index slightly higher than the commercially established standard (1.08%), besides presenting some metals very dangerous to health, such as arsenic. The production of ferric coagulant was also studied by dissolving the ferrous sulphate crystals and iron oxidation by adding aqueous solutions with acidic and oxidizing agents. The best condition obtained was as follows: 5 g of ferrous sulphate, 7.5 ml of distilled water, 1.5 ml of hydrogen peroxide and, 5 drops of sulfuric acid. This pro-portion provided a coagulant with almost 12% iron, with 97% of this iron in the ferric form. The coagulant produced was used in the water treatment of lake Guaíba, using as reference the Brazilian standards of potability. The coagulant produced showed to be efficient in the water treatment for public supply purposes.

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45

Dieter, Jonathan. "Transferência de fósforo por escoamento superficial devido à aplicação de água residuária da suinocultura e à adubação mineral em solo com diferentes declividades sob condição de chuva simulada." Universidade Estadual do Oeste do Parana, 2013. http://tede.unioeste.br:8080/tede/handle/tede/179.

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Made available in DSpace on 2017-05-12T14:46:57Z (GMT). No. of bitstreams: 1 Jonathan Dieter.pdf: 2302102 bytes, checksum: e9ab008e789823e27a423fd2b3bb0228 (MD5) Previous issue date: 2013-11-13
Swine wastewater application (SWW) in soils under no-tillage system can result in increased levels of phosphorus on soil surface layers, reducing the transferring risk via runoff into the aquatic environment. This trial aimed at evaluating, in two periods of soybean cropping, phosphorus transportation with the drained surface due to SWW application and mineral fertilization (MF) to a soil under no-tillage system with different declivities (i) and submitted to the simulation of different rain intensities (Ip). The trial was carried out on a Eutrophic Red Latosol. The study consisted in applying SWW doses (0, 75, 150, 225 and 300 m3.ha-1) with MF doses of (0%, 25%, 50%, 75% and 100% recommended to the crop) on 0.70 m2 soil plots with different declivities (i) (4, 9, 14, 19 and 24%) followed by the Ip simulation (45, 60, 75, 90 and 105 mm h-1) in two periods just after fertilizer application and seeding (AFAP) and after soybean harvest (ASH). After the runoff, it was simulated the Ip during 72 minutes by collecting independent samples drained solution at intervals of 24 minutes. The concentrations of total phosphorus (Pt), particulate phosphorus (Pp) and soluble phosphorus (Ps) were determined based on the collected samples. The central composite rotational design (CCRD) was used in a complete factorial design 24, with axial points (α = (2n)1/4), totaling 28 essays analyzed as a repeated measure along time. It was observed that concentrations of Pt, Ps and Pp in the runoff solution were positively influenced and showed the following order ARS> i> Ip. The multiple linear regression models adjusted for Ps and Pp concentrations in the runoff solution showed that SWW enhances the Ps transferring to the aquatic environment, while the factors that influence the transportation (i and Ip) showed greater importance in the concentration of transported Pp. During runoff, it was observed that the highest concentrations of Pt, Ps and Pp occurred at the beginning of runoff from the AFAP period, whose Pt concentrations reduced nearly 0.45 mg.L-1 during the ASH period. SWW application enhanced phosphorus transportation through runoff and reached higher concentrations when compared to those established ones by law. Thus, it represents a potential contamination to the environment
A aplicação de água residuária da suinocultura (ARS) em solos sob plantio direto pode resultar no aumento dos teores de fósforo em suas camadas superficiais, a fim de atenuar o risco de transferência via escoamento superficial para o meio aquático. O objetivo do trabalho foi avaliar, em dois períodos da cultura da soja, o transporte de fósforo junto à solução escoada na superfície devido à aplicação de ARS e a adubação mineral (ADM) no solo conduzido em plantio direto com diferentes declives (i) e submetido à simulação de diferentes intensidades de chuva (Ip). O experimento foi conduzido em Latossolo Vermelho eutroférrico. O trabalho consistiu da aplicação de doses de ARS (0, 75; 150; 225 e 300 m3.ha-1) juntamente com doses de ADM (0%, 25%, 50%, 75% e 100% recomendadas para a cultura) sobre parcelas de solo de 0,70 m2 com diferentes declives (i) (4, 9, 14, 19 e 24 %), seguido da simulação da Ip (45, 60, 75, 90 e 105 mm h-1) em dois períodos, logo após aplicação das adubações e semeadura (APA) e após a colheita da soja (APC). Após o início do escoamento superficial, simulou-se a Ip por um período de 72 minutos. Coletaram-se amostras independente da solução escoada em intervalos de 24 minutos. Determinaram-se as concentrações do fósforo total (Pt), fósforo particulado (Pp) e fósforo solúvel (Ps) nas amostras coletadas. Utilizou-se o delineamento composto central rotacional (DCCR), em planejamento fatorial completo 24, com pontos axiais (α =(2n)1/4), totalizando 28 ensaios, analisados como medida repetida no tempo. Observou-se que as concentrações de Pt, Ps e Pp na solução escoada foram influenciadas positivamente e na seguinte ondem ARS>i>Ip. Os modelos de regressão linear múltiplos ajustados sobre as concentrações Ps e Pp na solução escoada demostraram que a ARS potencializa a transferência de Ps para o meio aquático, enquanto os fatores que influenciam no transporte (i e Ip) têm maior importância na concentração de Pp transportado. Durante o escoamento superficial, se observou que as maiores concentrações de Pt, Ps e Pp ocorrem no início do escoamento superficial do período APA, cujas concentrações de Pt foram reduzidas em torno de 0,45 mg.L-1 no período APC. A aplicação de ARS potencializou o transporte de fósforo via escoamento superficial e atingiu concentrações superiores às estabelecidas pela legislação, representando assim um potencial de contaminação ambiental

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46

Clough, Tim J. "Fate of urine nitrogen applied to peat and mineral soils from grazed pastures." Lincoln University, 1994. http://hdl.handle.net/10182/1030.

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This study has provided fundamental information on the fate of urine nitrogen (N) when applied to pasture soils. In this work the three pasture soils used were a Bruntwood silt loam (BW), an old well-developed (lime and fertilizer incorporated and farmed for more than 20 years) peat soil (OP) and a young peat (YP) which was less developed (farmed for about 10 years). Initial soil chemical and physical measurements revealed that the peat soils were acidic, had higher cation exchange capacities, had greater carbon:nitrogen ratios and were better buffered against changes in soil pH than the BW soil. However, the BW soil was more fertile with a higher pH. The peat soils had lower bulk densities and higher porosities. Four experiments were performed. In the first experiment ¹⁵N-labelled urine was applied at 500 kg N ha⁻¹ to intact soil cores of the three soils. Treatments imposed were the presence and absence of a water table at two temperatures, 8°C or 23° C, over 11-14 weeks. ¹⁵N budgets were determined. This first experiment showed that the nitrification rate was faster in the BW soil and was retarded with a water table present. Significant leaching of nitrate occurred at 8°C in the BW soil without a water table. This was reduced when a water table was present. Leaching losses of urine-N were lower in the peat soils than in the BW soil. Apparent denitrification losses (i.e. calculated on a total-N recovery basis) ranged from 18 to 48 % of the ¹⁵N-applied with the greatest losses occurring in the peat soils. The second experiment examined denitrification losses, over 30 days, following the application of synthetic urine-N at 420 kg N ha⁻¹ to small soil cores situated in growth cabinets. The effects of temperature (8°C or 18°C) and synthetic urine (presence or absence) were measured on the BW and OP soils. Nitrous oxide (N₂0) measurements were taken from all soil cores and a sub-set of soil cores, at 18°C, had ¹⁵N-labelled synthetic urine-N applied so that ¹⁵N-labelled nitrogen gases could be monitored. This experiment showed that the application of synthetic urine and increased soil temperature enhanced denitrification losses from both soils. Denitrification losses, at 18°C, as ¹⁵N-labelled nitrogen gases accounted for 24 to 39 % of the nitrogen applied. Nitrous oxide comprised less than half of this denitrification loss. Losses of N₂0 in leachate samples from the soil cores accounted for less than 0.1 % of the nitrogen applied. A third experiment, using Iysimeters, was performed over a 150 day period in the field. The six treatments consisted of the 3 soils with applied synthetic urine, with or without a simulated water table; each replicated three times. Lysimeters were installed in the field at ground level and ¹⁵N-labelled synthetic urine-N was applied (500 kg N ha⁻¹) on June 4 1992 (day 1). Nitrification rates differed between the soils following the trend noticed in the first experiment. As in the first experiment, nitrate was only detected in the leachate from the BW soil and the inclusion of a water table reduced the concentration of nitrate. In the BW soil, the leachate nitrate concentrations exceeded the World Health Organisation's recommended limit (< 10 mg N L-1) regardless of water table treatment. No nitrate was detected in the leachates from the peat soils but there was some leaching of organic-N (< 5 % of N added) in all the peat soil treatments. Denitrification losses were monitored for the first 100 days of the experiment. In the BW soil without a water table, N₂0 production peaked at approximately day 20 and accounted for 3 % of the nitrogen applied. In the peat soils the measured denitrification losses accounted for less than 1 % of the nitrogen applied. Apparent denitrification losses in the peats were, however, calculated to be approximately 50 % of the ¹⁵N-labelled synthetic urine-N applied. It is postulated that the difference between apparent denitrification losses and those measured could have been due to; loss of dinitrogen in leachate, protracted production of dinitrogen below detectable limits, production of denitrification gases after measurements ceased (i.e. days 100 to 150) and entrapment of dinitrogen in soil cores. Due to the apparent denitrification losses being so high, further research into this nitrogen loss pathway was performed. The fourth and final experiment measured denitrification directly using highly enriched (50 atom %) ¹⁵N-labelled synthetic urine-N. It was performed in a growth cabinet held initially at 8°C. The ¹⁵N-labelled synthetic urine was applied at 500 kg N ha⁻¹ to small soil cores of each soil type. Fluxes of N₂0 and ¹⁵N-labelled gases were measured daily for 59 days. On day 42 the temperature of the growth cabinet was increased to 12°C in an attempt to simulate the mean soil temperature at the end of the field experiment. Up to this time, production of nitrogenous gases from the YP soil had been very low. Interpretation of gaseous nitrogen loss in the YP soil was difficult due to the possibility of chemodenitrification occurring. However, in the OP and BW soils, gaseous losses of nitrogen (determined as ¹⁵N-labelled gas) represented 16 and 7 % of the nitrogen applied respectively. Nitrous oxide comprised approximately half of this gaseous nitrogen loss, in both the OP and BW soils. This work implies that urine-N applied to the mineral soil (BW) could potentially threaten the quality of ground water due to nitrate contamination through leaching. In contrast, denitrification appears to be the major loss mechanism from the peat soils, with the production of nitrous oxide being the primary focus for any environmental concern. Future work should examine the fate of the nitrate leached from the BW soil and the potential for dilution, plant uptake or denitrification below a 30 cm soil depth. A better understanding of the denitrification mechanisms could help reduce denitrification and thereby improve the efficiency of nitrogen use and reduce the output of nitrous oxide.

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Fatoba, Ojo Olanrewaju. "Chemical interactions and mobility of species infly ash-brine co-disposal systems." Thesis, University of the Western Cape, 2010. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_5672_1305271283.

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The primary aim of these coal fired industries for co-disposing fly ash and brine was to use the fly ash as a sustainable salt sink. It is therefore important to study the interaction chemistry of the fly ash-brine systems to fully understand the leaching and mobility of the contaminant species, and to determine the possibility of capturing the salts from the brine solution when fly ash and brine are co-disposed. In order to achieve the aims and objectives of this study, several leaching procedures such as batch reaction tests, long-term fly ash-brine interaction tests, acid neutralization capacity (ANC) tests, up-flow percolation tests and sequential extraction tests were employed. The geochemical modeling software was applied to predict the formation of secondary mineral phases controlling the release of species in the fly ash-brine systems. Several analytical techniques such as x-ray diffraction (XRD), x-ray fluorescence (XRF), scanning electron microscopy-energy dispersion spectroscopy (SEM-EDS), inductively coupled plasma-mass spectroscopy (ICP-MS) and ion chromatography (IC) were applied to characterize the fresh fly ashes, solid residues recovered from the fly ash-brine interaction tests, the brine sample used in this study and the leachate samples in order to determine the chemical and mineralogical compositions and speciation of the waste materials.

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Adipuri, Andrew Materials Science &amp Engineering Faculty of Science UNSW. "Chlorination of Titanium Oxycarbide and Oxycarbonitride." Publisher:University of New South Wales. Materials Science & Engineering, 2009. http://handle.unsw.edu.au/1959.4/44405.

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The project undertook a systematic study of chlorination of titanium oxycarbide and oxycarbonitride with the aim to develop further understanding of kinetics and mechanisms of the chlorination reactions. The project studied titania, ilmenite ores, and synthetic rutile reduced by carbon in argon and nitrogen and chlorinated at different temperatures, gas flow rates and compositions. Chlorination of titanium suboxides, iron and impurities in ilmenite was also examined. Chlorination of titanium oxycarbide Ti(O,C) or oxycarbonitride Ti(O,C,N) can be implemented at 200 to 400 deg.C, while the commercial chlorination process in the production of titanium metal or titania pigment requires 800 to 1100 deg.C. This makes chlorination of Ti(O,C) or Ti(O,C,N) an attractive technology in processing of titanium minerals. Chlorination reaction is strongly exothermal, which increased the sample temperature up to 200 deg.C above the furnace temperature. The chlorination of Ti(O,C) or Ti(O,C,N) was ignited at 150 deg.C to 200 deg.C depending on the sample composition. Their chlorination at 235 deg.C to 400 deg.C was close to completion in less than 30 min. The chlorination rate of titanium oxycarbide or oxycarbonitride increased with increasing gas flow rate. Sample composition had a significant effect on the extent of chlorination. The optimum results were obtained for titanium oxycarbide or oxycarbonitride produced with carbon to titania molar ratio of 2.5; these samples contained no detectable excess of carbon or unreduced titanium suboxides. In chlorination of reduced ilmenite ores and synthetic rutile, Ti(O,C) or Ti(O,C,N), metallic iron and Ti2O3 were chlorinated. The rate and extent of chlorination of titanium increased with increasing carbon to TiO2 ratio. Chlorination of Ti2O3 was slow relative to Ti(O,C) or Ti(O,C,N) and iron; chlorination of impurity oxides such as MgO, SiO2 and Al2O3 was not observed. The project also examined chlorination of Ti(O,C) or Ti(O,C,N) in ilmenite ore and synthetic rutile after removal of iron, which was achieved by aerated leaching of reduced samples in heated flask containing 0.37 M of ammonium chloride solution. Iron removal from the ilmenite ore or synthetic rutile resulted in higher rate and extent of chlorination of titanium oxycarbide or oxycarbonitride.

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Piatnicki, Slawomir. "Lixiviation de minerais aurifères et électrolyse directe des solutions diluées sur une cathode volumique poreuse percolée pulsée : application aux petits gisements d'or." Vandoeuvre-les-Nancy, INPL, 1994. http://www.theses.fr/1994INPL040N.

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L'objectif de l'étude est l'application d'un procédé basé sur la lixiviation statique suivie de l'électrolyse directe (LSED) a la valorisation de petits gisements d'or, notamment les petits gisements amazoniens du brésil dont la production représente 75% de l'or produit dans ce pays, bien que compte tenu des techniques artisanales utilisées les taux de récupération de l'or ne dépassent pas 30 à 40% comme le montre l'état de l'art. Le procédé LSED a été appliqué à 3 minerais types différents quant aux métaux accompagnateurs et à la para genèse: il s'agit du minerai du chapeau de fer du gisement du rouez (France), du filon de quartz d'essakane (Burkina Faso) et du minerai sulfure complexe de volta grande (Brésil). Les taux de mise en solution varient de 70 à 90%. L'électrolyse directe effectuée sur les solutions de lixiviation diluées (3 à 8 mg au/l) permet d'atteindre des rendements d'électrodéposition très élevés, mais alors les rendements faradiques sont très bas et par conséquent les consommations énergétiques très élevées. L'analyse des dépôts électrolytiques au microscope électronique à balayage montre des structures non orientées, plurimétalliques et de morphologie variable. Le procédé LSED peut s'appliquer industriellement a un minerai d'or pauvre en métaux accompagnateurs, avec lixiviation en tas de 2000 t et en employant des électrolyseurs d'un volume unitaire de 1000 l minimum. Dans ce cas, après environ 7 h d'électrolyse directe, on peut récupérer 60% de l'or avec une consommation d'environ 800 kwh/kgau

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Faivre, Pierre. "Lessivage et planosolisation dans les séquences de sols caractéristiques des milieux intrandins de Colombie (Amérique du sud)." Nancy 1, 1988. http://www.theses.fr/1988NAN1A002.

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Étude des couvertures pédologiques complexes des versants des dépressions andines qui sont organisées en climatoséquences et développées à partir de pyroclastiques. On retrouve des andosols, des ferrisols (sombritropepts, sombrihumults), brunizem (argiudolls, arguistolls) et des planosols (haplustalfs, naturstafs). Tout le long du profil le cortège argileux est constitué d'halloysite. Les facteurs intensifiant le lessivage vers l'aval sont étudiés. Dans les couvertures anciennes des caractères polygénétiques sont décelables dans certains profils de planosols. Une étude des isotopes stables du carbone permet d'établir le sens des variations paléoécologiques et paléoclimatologiques

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