Dissertations / Theses on the topic 'Ore mineral'

Tailings dams, due to their sheer size and metal content, pose safety and environmental hazards. The Småltjarnen repository, which hosts material from the largest known tungsten mineralization in Sweden named the Yxsjöberg deposit, is estimated to contain 2.2 million tons of material from previous operations when recovery rates of scheelite, chalcopyrite, and fluorite were low. The repository is also observed to contain at least four of the listed critical raw materials by the European Commission in 2017, namely tungsten, fluorite, beryllium, and bismuth. The amenability of this tailings repository as secondary sources for valuable minerals and metals supports the Raw Material Initiative and the drive of the European Union towards a more circular economy. This masters thesis is part of the REMinE (Improve Resource Efficiency and Minimize Environmental Footprint) project that aims to evaluate the amenability of historical mining waste for re-processing from the technical, economical, and environmental perspectives. The study focuses on work package 3 of the project: Identification of new processing methods for mine waste. Previous work on this repository includes geochemical characterization and physical separation through magnetic and gravity separation tests. Since scheelite, the main mineral of the deposit, is commonly recovered through combinations of gravity separation and flotation methods, it is imperative to investigate the response of the material to flotation tests. Further characterization work and flotation tests were rendered on samples from sampling location 6 (60°02'33.6"N 14°46'30.8"E). Previous work was done on samples from and near sampling location 1, which is southwest from location 6. Characterization methods performed on the material included elemental analysis through ICP-SFMS, X-ray diffraction measurements, and mineral liberation analysis as well as physical characterization through particle size distribution analysis and determination of specific gravity. Based on MLA, the material from the main samples showed good liberation by free surface which is important for flotation processes. Mineral association also showed low percentages between scheelite and other Ca-bearing minerals which is a main concern for scheelite flotation. Comparison of characterization work between the two sampling locations allows information on the repository at a larger scope. The common scheelite flotation collector sodium oleate, as well as novel formulations Atrac 2600 and Berol 8313 from Nouryon were tested in combination with the depressant sodium silicate. Based on mass recovery, grade and recovery, selectivity, required dosage, and the degree to which it is environmentally safe, Atrac 2600 at 400 g/t is deemed to produce the most positive results. Based on characterization of the material and flotation tests, an estimated 222,200 tons of -75 µm can go directly into the flotation circuit with an average grade of 0.2768% WO3 and 0.195% Cu. Approximately 15,000 tons at 0.50% WO3 and 14,000 tons at 0.224% Cu can be recovered at a single flotation. Rough mass balance of the process flowsheet indicates a Cu concentrate at 30% Cu will produce 880.50 tons, while a saleable scheelite concentrate at 65% WO3 will yield 672.16 tons from only the original -75 µm fraction of the material. Including the gravity separation tails intended to join the flotation circuit after grinding, an estimated 1,205.54 tons of scheelite at 65% WO3 and 1.860.20 tons of 30% Cu concentrate can be produced. Aside from this, the gravity separation circuit will still be able to yield 188,000 tons of 0.92% WO3 concentrate, which can be further studied if it can be beneficiated to a saleable product. Value estimation of the products for the recommended flowsheet indicate a total of US$ 17 million for the WO3 and Cu concentrates to be produced from the readily amenable -75 µm fraction to be treated directly by flotation. Inclusion of the gravity separation tails mass into the flotation feed yields a value estimated at US$32 million.

Includes abstract.<br>Includes bibliographical references (leaves 96-101).<br>This thesis investigates the effect of ore blends on milling and flotation performance. Anglo Platinum's Waterval UG2 concentrator in Rustenburg processes ore from various shafts.

Ore-forming processes are relatively well understood on Earth, but little is known about mineralization processes on Mars. By applying terrestrial analogs, using data collected from orbital and rover missions and evidence for hydrothermal activity from alteration assemblages, the types and locations of different ore-forming processes have been investigated with the aim of discovering concentrations of mineral resources on Mars. These resources are likely to be of critical importance for future manned missions to Mars, and insight gained towards mineralization on Mars may also advance our understanding of terrestrial deposits.

Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2016.<br>Nickel, a valuable base metal, is the predominant product from the Nkomati mine in South Africa. High-grade nickel mineral ores (2%) from the Massive Sulphide Body have been depleted leaving those of low grade (0.3%). The beneficiation of this ore presents a challenge to the minerals processing industry. In response, batch froth flotation tests were used to explore the effects of mixtures of potassium amyl xanthate (PAX) and IPETC (Isopropyl ethyl thionocarbamate) on the grades and recoveries of nickel. In the mixtures, the xanthate accounted for 95.5, 90, 85 and 80 mole% respectively. Generally an increase in the nickel grade and recovery was observed with the mixtures relative to PAX. IPETC gave a significant increase in the cumulative water recovery with a significant decrease in cumulative nickel grade relative to PAX. PAX gave the highest cumulative nickel grade for the singular collector tests (1.9%), while obtaining the lowest cumulative recovery (77%). Out of the collector mixtures, mixtures 85% PAX: 15% IPETC and 90% PAX: 10% IPETC produced the joint highest cumulative grades (1.8%). These mixtures both gave recoveries of 82%. Collector mixture 95.5% PAX: 4.5% IPETC gave the second highest grade (1.7%) and the highest nickel recovery (85%). Although there were differences in the cumulative nickel grades and recoveries there were statistically no significant improvements observed with the use of the mixtures of PAX and IPETC in comparison to the industry mixture (95.5% SIBX: 4.5% IPETC). Tests were performed using the three best performing collector mixtures at molar dosages of 1.3, 0.65 and 0.325mmol/t. The highest cumulative nickel grades were obtained at the lowest collector dosages (at a molar dosage of 0.325mmol/t of 95.5% SIBX: 4.5% IPETC) with collector mixture 95.5% PAX: 4.5% IPETC being the most selective with a nickel grade of 2%. It was also observed that an increase in collector dosage, generally increased the cumulative nickel recovery with collector mixture 95.5% PAX: 4.5% IPETC at a molar dosage of 1.3mmol/t gave the highest cumulative recovery out of the tested mixtures (85%). The study also indicated that an increase in selectivity (i.e. cumulative grade) was at the expense of cumulative recovery. With a decrease in dosage, there was no significant improvement in the cumulative nickel grade and recovery for the tested mixtures compared to the industry mixture. There was however a significant decrease in the water recoveries achieved with PAX and collector mixtures 95.5% PAX: 4.5% IPETC at a molar dosage of 1.3mmolg/t of as well as mixture 90% PAX: 10% IPETC at a molar dosage of 0.65mmol/t.

Thesis (PhD)--University of Stellenbosch, 2004.<br>ENGLISH ABSTRACT: The Gamsberg Zn-Pb deposit is a metamorphosed and multiply deformed sediment-hosted base metal deposit in the central Namaqua Province of South Africa. The deposit is hosted by the Bushmanland Group, a late Palaeoproterozoic (2000-1600 Ma) supracrustal succession of quartzite, metapelitic schist and interbedded metavolcanic rocks. Mineralisation occurs within the central part of the Gams Formation, a heterogeneous sequence of metamorphosed metalliferous sediments and fine-grained organic-rich shales. The ore horizon is subdivided into a lower unit of metapelite-hosted ore, an intermediate layer of phosphorite-hosted ore, and an upper unit of banded garnet-apatite ore. The ore body is enveloped by unmineralised silicate-, carbonate- and oxide-facies metalliferous rocks, which originally represented mixtures of Fe-Mn-rich hydrothermal precipitates, authigenic carbonate, and variable concentrations of detrital material. Based on mineralogical and geochemical characteristics, the metalliferous host rocks are subdivided into iron formations, coticules, Fe-Mn silicates, impure marbles and barite/Ba-rich quartzite. Minerals of the Gams Formation mostly represent solid solution between the Fe and Mn end-members of garnet, pyroxene, pyroxenoid, amphibole, olivine, spinel and ilmenite. Calcium-rich rock types are a typical feature and characterized by the occurrence of manganoan calcite, clinopyroxene, andradite-rich garnet and titanite. A successive increase in the (Mn+Ca):Fe value of rocks and minerals is evident with increasing distance from the ore horizon. Amphibole is restricted to Fe-rich ore-bearing assemblages, whereas orthopyroxene, clinopyroxene, Fe-rich pyroxenoid and olivine are present in intermediate assemblages, and Mn-rich rhodonite and pyroxmangite in the most manganiferous assemblages. These variations are mimicked by an increase in the Mn:Fe value of coexisting garnet and ilmenite group minerals with increasing distance from ore. LA-ICP-MS analyses have been used to constrain the REE patterns of garnet and apatite. In the ore-body, these minerals display a positive Eu anomaly, which is interpreted to reflect a distinct hydrothermal signature. In contrast, garnet and apatite in unmineralised metalliferous rocks display nil or a negative Eu anomaly. Primary features of the Gams Formation, such as REE patterns, the banded nature of garnet-apatite ore, the presence of diagenetic apatite nodules, and the distribution of the redox-sensitive elements Ba and Mn have been used to constrain palaeo-environmental conditions. The results indicate that metapelitehosted ore has been deposited in a stratified ocean that was characterised by anoxic bottom waters and precipitation of Fe and Zn sulphides into organic matter-rich shales. These rocks were superceded by phosphorite-hosted ore, garnet-apatite ore and metalliferous host rocks that developed in a suboxic to oxic environment. The large size of the deposit, the internal lamination of the ores and the predominance of sphalerite and barite are consistent with a vent-distal setting and precipitation of the ore-forming constituents from dense and reduced hydrothermal fluids, which originated due to reactivation of dormant growth faults. Collectively, the geological evidence indicates that Gamsberg is bridging the gap betweenthe SEDEX and BHT classifications. The relationships demonstrate that differences between these two classes of sediment-hosted Zn-Pb deposits are predominantly related to environmental conditions within localised third order basins and not to fundamental differences in ore-forming processes.<br>AFRIKAANSE OPSOMMING: Die Gamsberg Zn-Pb afsetting is ‘n meerfasig vervormde en gemetamorfiseerde sedimentgesetelde onedel metaal afsetting in die sentrale Namakwa Provinsie van Suid Afrika. Die afsetting word geherberg deur die Boesmanland Groep, ‘n laat Paleoproterosoïse (2000 – 1600 Ma) bokors-opeenvolging van kwartsiet, metapelitiese skis en tussengelaagde metavulkaniese gesteente. Mineralisasie word gevind in the sentrale deel van die Gams Formasie. Die Gams Formasie is ‘n heterogene opeenvolging van gemetamorfiseerde metaalhoudende sediment en fynkorrelrige organiese skalie. Die erts horison word onderverdeel in ‘n onderste laag van metapeliet-gesetelde erts, n sentrale laag van fosforiet-gesetelde erts, en ‘n boonste laag van gebande granaat-apatiet erts. Die erts-liggaam word omhuls deur ongemineraliseerde silikaat-, karbonaat- en oksied-fasies metal-ryke rotse. Hierdie gesteentes word geinterpreteer as oorspronklike mengsels van Fe-Mn-ryke hidrotermale partikels, outigeniese karbonaat, en verskeie hoeveelhede detritale materiaal. Gebaseer op mineralogiese en geochemiese kenmerke word hierdie rotse onderverdeel in ysterformasies, „coticules“, Fe-Mn silikate, onsuiwer marmer en barite/Ba-ryke kwartsiet. Minerale van die Gams Formasie form meestal soliede oplossingsreekse tussen die Fe en Mn endlede van granaat, pirokseen, piroksenoid, amfibool, olivien, spinel en ilmeniet. Kalsium-ryke rots tipes is ‘n tipiese kenmerk van die Gams Formasie en word gekenmerk deur mangaan-ryke kalsiet, klinopirokseen, andradiet-ryke granaat en sfeen. Daar word ‘n stapsgewyse vergroting van die (Mn+Ca):Fe verhouding in gesteentes en minerale gevind met toeneemende afstand van die erts horison. Amfibool is beperk tot Fe-ryke ertsdraende gesteentes, ortopirokseen, klinopirokseen, Fe-ryke piroksenoid en olivien tot intermediêre gesteentes, en Mn-ryke rodoniet en piroksmangiet tot Mn-ryke gesteentes. Hierdie variasies gaan gepaard met vergroting van die Mn:Fe verhouding in granaat en ilmeniet-groep minerale met toeneemende afstand van die erts. LA-ICP-MS analises was gebruik om die skaars-aarde element patrone van granaat en apatiet te bepaal. In die erts-liggaam wys hierdie minerale ‘n positiewe Eu anomalie, wat geinterpreteerd word as ‘n hidrotermale kenmerk. In ongemineraliseerde gasheer gesteentes wys granaat en apatiet geen of ‘n negatiewe Eu anomalie. Primêre kenmerke van die Gams Formasie, soos skaars-aarde patrone, the gebande voorkoms van granaat-apatiet erts, die teenwoordigheid van diagenetiese apatiet knolle, en die verspreiding van die redox-sensitiewe elemente Ba en Mn, was gebruik om afleidings oor die paleo-omgewing te maak. Die resultate het gewys dat metapeliet-gesetelde erts afgeset was onder anoksiese bodem water deur presipitasie van Fe en Zn sulfiedes in organiese skalie. Hierdie erts gaan oor in fosforiet-gesetelde erts, granaat-apatiet erts en metaal-ryke gasheer gesteente wat in ‘n suboksiese tot oksiese omgewing ontstaan het. Die grootte van die afsetting, die interne gelaagdheid van die erts, asook die teenwoordigheid van sfaleriet en bariet dui op ‘n distale omgewing relatief tot die hidrotermale bron en presipitasie van die ertsuit digte en gereduseerde hidrotermale vloeistowwe, wat ontstaan het deur die heraktiveering van rustende groeiverskuiwings. Gesaamentlik bewys die geologiese kenmerke van Gamsberg dat gemetamorfiseerde SEDEX en Broken Hill-tipe mineralisasie binne die perke van ‘n enkele afsetting kan voorkom. Die geologiese verhoudings dui aan dat verskille tussen hierdie twee tipes van sedimentgesetelde afsettings meestal veroorsaak word deur omgewings-toestande binne in gelokaliseerde derde orde komme en nie deur fundamentele verskille in ertsvormende prosesse nie.

As the demand for a low-carbon and environmentally friendly future increases, so does the importance of mineral and metal commodities. The production of solar panels, wind turbines, energy storage systems and other green technologies require large quantities of minerals and rare earth metals. Natural Resources Canada noted that in 2019, Canada was a global leading producer in minerals required for green technology including graphite, nickel, cobalt, and others [1]. While mineral production continues to rise year over year, the ore grade, i.e., the concentration of a desired material, of multiple common minerals continues to decline. To liberate valuable minerals from low ore grade deposits size reduction processes such as crushing and grinding are required; however, these processes account for over half of all energy consumption on the average mine. As mines are typically remote, fossil fuels are normally used as the main energy source, producing large amounts greenhouse gases, necessitating the need for more efficient size reduction processes. This could be accomplished by predicting how a particular orebody would break. With the surge in image sensing and computing technologies at mining sites many researchers are exploring ore texture and processability characteristics of the ore body. If distinct processability characteristics change based on ore textural feature from a 2D image, then general trends for optimal size reduction of orebodies of similar texture can developed. This work builds on previous work by simulating ore breakage through the superimposition of a predetermined fragmentation pattern, called a mask, onto multiple ore textures. Synthetic, periodic black and white 2D ore textures were created to find a link between simple textural features such as different mineral grain shape, size, and orientation and processability characteristics. A Monte Carlo simulation was performed to generate a large quantity of realistic product particles using the Voronoi tessellations masking technique. To assess the processability of different textures, the percentage area distribution of valuable minerals of each ore texture was compared across the complete range of particle sizes. The valuable mineral percentage area distributions were analyzed for rate and shape of the distribution as particle size decreases, with noticeable differences between textures. The distributions were also parameterized using a two-beta mixture distribution model, expanding on the traditional one beta model developed by King [2,3,4]. These distributions can eventually help the mining industry make informed decisions on how much grinding and crushing will be required to liberate desired minerals from waste rock.

Thesis (M.S.)--Missouri University of Science and Technology, 2008.<br>Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed May 9, 2008) Includes bibliographical references (p. 131-139).

The demands for efficient utilization of ore bodies and proper risk management in the mining industry have resulted in a new cross-disciplinary subject called geometallurgy. Geometallurgy connects geological, mineral processing and subsequent downstream processing information together to provide a comprehensive model to be used in production planning and management. A geometallurgical program is an industrial application of geometallurgy. Various approaches that are employed in geometallurgical programs include the traditional way, which uses chemical elements, the proxy method, which applies small-scale tests, and the mineralogical approach using mineralogy or the combination of those. The mineralogical approach provides the most comprehensive and versatile way to treat geometallurgical data. Therefore it was selected as a basis for this study. For the mineralogical approach, quantitative mineralogical information is needed both for the deposit and the process. The geological model must describe the minerals present, give their chemical composition, report their mass proportions (modal composition) in the ore body and describe the ore texture. The process model must be capable of using mineralogical information provided by the geological model to forecast the metallurgical performance of different geological volumes and periods. A literature survey showed that areas, where more development is needed for using the mineralogical approach, are: 1) quick and inexpensive techniques for reliable modal analysis of the ore samples; 2) ore textural characterization of the ore to forecast the liberation distribution of the ore when crushed and ground; 3) unit operation models based on particle properties (at mineral liberation level) and 4) a system capable of handling all this information and transferring it to production model. This study focuses on developing tools in these areas. A number of methods for obtaining mineral grades were evaluated with a focus on geometallurgical applicability, precision, and trueness. A new technique developed called combined method uses both quantitative X-ray powder diffraction with Rietveld refinement and the Element-to-Mineral Conversion method. The method not only delivers the required turnover for geometallurgy but also overcomes the shortcomings if X-ray powder diffraction or Element-to-Mineral Conversion were used alone. Characterization of ore texture before and after breakage provides valuable insights about the fracture pattern in comminution, the population of particles for specific ore texture and their relation to parent ore texture. In the context of the mineralogical approach to geometallurgy, predicting the particle population from ore texture is a critical step to establish an interface between geology and mineral processing. A new method called Association Indicator Matrix developed to assess breakage pattern of ore texture and analyze mineral association. The results of ore texture and particle analysis were used to generate particle population from ore texture by applying particle size distribution and breakage frequencies. The outcome matches well with experimental data specifically for magnetite ore texture. In geometallurgy, process models can be classified based on in which level the ore, i.e. the feed stream to the processing plant and each unit operation, is defined and what information subsequent streams carry. The most comprehensive level of mineral processing models is the particle-based one which includes practically all necessary information on streams for modeling unit operations. Within this study, a particle-based unit operation model was built for wet low-intensity magnetic separation, and existing size classification and grinding models were evaluated to be used in particle level. A property-based model of magnetic beneficiation plant was created based on one of the LKAB operating plants in mineral and particle level and the results were compared. Two different feeds to the plant were used. The results revealed that in the particle level, the process model is more sensitive to changes in feed property than any other levels. Particle level is more capable for process optimization for different geometallurgical domains.

Efficient measurement methods for comminution properties are an important prerequisite for testing the variability of an ore deposit within the geometallurgical context. This involves the investigation of effects of mineralogy and mineral texture on the breakage of mineral particles. Breakage properties of mineral particles are crucial for the liberations of minerals and the energy required for that. For process optimization and control purposes, comminution indices are often used to map the variation of processing properties of an entire ore body (e.g. Bond work index). Within the geometallurgical approach this information is then taken up when modelling the process with varying feed properties. The main focus of this thesis work has been to develop a comprehensive geometallurgical testing framework, the Geometallurgical Comminution Test (GCT), which allows the time and cost efficient measurement of grinding indices and their linkage to mineralogical parameters (e.g. modal mineralogy or mineral texture, mineral liberation). In this context a small-scale grindability test has been developed that allows estimating the Bond work index from single pass grinding tests using small amounts of sample material. Verification of the evaluation method and validation was done with different mineral systems. For selected samples the mineral liberation distribution was investigated using automated mineralogy. By transferring the energy-size reduction relation to energy – liberation relation new term liberability has been established. As part of the experimental investigations, mineralogical parameters and mineral texture information were used for predicting breakage and liberation properties. Patterns for describing the breakage phenomena were established for a set of iron oxide ore samples. The determined breakage patterns indicated that the specific rate of mineral breakage slows down when reaching the grain size of mineral particles, thus allowing maximizing mineral liberation significantly without wasting mechanical energy.<br>CAMM

Conselho Nacional de Desenvolvimento Científico e Tecnológico<br>Em trabalho de prospecção geoquímica regional por concentrado de bateia (PEREIRA e SANTOS, 1983) foi evidenciado na região de Cacaria, município de Piraí, ocorrências de scheelita. Com o objetivo de investigar a possível fonte litológica desta ocorrência, foram realizadas amostragens de sedimentos de corrente e concentrado de bateia além de investigações de campo para sua fonte. Elaborouse ainda um mapa geológico em escala de detalhe 1:25.000. As unidades estratigráficas base utilizadas no mapa foram definidas em trabalhos da empresa RIOFINEX (1977) durante pesquisas para mineralizações de Pb-Zn na região de Rio Claro. Ensaios laboratoriais envolvendo descrição de lâminas petrográficas, difratometria de raios X, fluorescência de raios X, espectrometria Raman, microscopia eletrônica de varredura e o auxílio do mineralight de ondas curtas. As mineralizações scheelitíferas encontradas foram classificadas segundo um modelo do tipo sedimentar exalativo, localmente com possíveis contribuições de atividades metassomáticas tardias, concentrando a mineralização, assim como proposto para algumas ocorrências já descritas no nordeste brasileiro.<br>In a mineral exploration panning concentrate programme PEREIRA AND SANTOS (1985) identified in the Cacaria region, near the Piraí City, occurences of scheelite. With the objective to investigate the lithological origin of this mineral a nonsystematic sampling by stream sediments and panning concentrate, was carried out to identify the tungsten mineralization source. A geological map was also executed at detailed scale of 1:25.000. The stratigraphic division applied to this map was defined in projects of RIOFINEX (1977) company during investigation of Pb-Zn mineralization in Rio Claro. Laboratorial trials involving description of petrography, Xray diffraction, X-ray fluorescence, Raman spectroscopy, electronic microscopy scanning and short wave mineralight. The scheelite-bearing mineralization was classified according to a exhalative sedimentary model with possible contributions of a late metasomatic activities concentrating the mineralization as proposed for some occurrences observed in northeast part of Brazil.

Part 1- Abstract This research study presents detailed petrographic- and geochemical- analysis of 63 rock samples from the Atchiza Suite. The Suite is a layered mafic-ultramafic pluton located in the Tete Suite, of NW Mozambique. At present, the Atchiza comprises a group of three main types of rock that are classified based on their mineralogy, textures, geochemical composition. These are ultramafic cumulates (dunite and pyroxenites), mafic cumulates (medium-grained cumulate gabbro) and coarse-grained gabbro (non-cumulate gabbro). Compared to the rest of other rocks, coarse-grained gabbro shows high enrichment of Ti (0.64-3.46 wt% TiO2), Zr (5.9-296.1 5ppm), Sr (253.7-1268.4ppm) and V (224-952.3ppm), but relatively low depleted in compatible elements (Ni = 48.7-235.7ppm , Cr = below detection limit to 410.5ppm). Cumulate ultramafics are highly enriched in compatible elements (Ni up to 4636.2ppm, Cr up to 4721ppm). A high Mg# in ultramafic cumulates (0.59-0.86) suggests an Mg-rich primitive parental magma, whereas a low Mg# in coarse-grained gabbro (0.23-0.37) suggests a relatively high-differentiated magma. Cumulate gabbro shows Mg# ranging from 0.40-0.72, suggesting a moderately evolved magma source (derivative magma subsequent to fractionation of ultramafic cumulates). The Ni/Zr, Cr/Zr, Sr/Zr and Ti/Zr ratios are generally the lowest in coarse-grained gabbro when compared to cumulate rocks. The same applied; this suggests that coarse-grained gabbros were probably formed from a relatively high-differentiated magmatic liquid. In addition, the presence of an uninterrupted cryptic differentiation trend with these ratios implies that the Atchiza igneous lithologies were derived from one and the same parental melt. Apparently, Atchiza shows great variability of Fe2O3, SiO2 and SO3 during magmatic differentiation. There is significant decrease in Fe2O3, an increased SiO2 and SO3 contents in residual magma during progressive magma fractionation. It is true that all these geochemical changes will lower down the solubility of S in the system, thus providing a favourable condition for silicate-sulfide immiscibility. Theoretically, therefore, the Atchiza may have a potential to host Ni-Cu-(PGE) sulfide deposits. Part 2- Abstract Unlike water and forests, minerals are finite resources; they cannot be replaced back to their natural forms once they are depleted. For that reason, sustainable management of mineral resources is very important so that stakeholders in the extractive sector are guaranteed the same opportunities in sharing benefits. As part of this study, and with respect to Atchiza Suite, this section is discussing sustainable management of mineral deposits in Mozambique. Investment in Mozambican extractive industry should primarily be done with the main objective of poverty reduction for Mozambican citizens. Thus, the Mozambican Government needs to realize that proper management of mineral deposits will provide sufficient income for the country, enough to fund other development projects. Rather than being mismanaged, this massive collection of mineral revenues needs to be appropriately re-invested back to diversify other economic sectors. If this mineral revenue is managed wisely, the national annual budgets will be sufficiently supported. Most importantly, the country’s reliance on international loans and aids will be reduced significantly. Decision-making for development of the country’s mineral projects should not be central-governed; rather it should be transparent to the public and open for opinions and suggestions. As the main stakeholder in Mozambican extractive sector, local communities and civil societal groups should also be given opportunities to participate in decision-making, important for the development of mining projects. Mineral agreements for which the Mozambican State has been signing with multinational companies for development of the country’s mineral projects need to be published and be available publicly. In addition, negotiation of mining agreements must be transparent and involve all stakeholders. Investment and development of the country’s mineral projects must be performed through partnerships and Joint ventures between multinational mining companies, national-based companies and the Mozambican State. Development of mineral deposits must incorporate environmental sustainability. Despite its high mineral potential (e.g. Ni-Cu-PGE-Ti-V), Atchiza also is surrounded by a wide range of other natural resources. The Cahora Bassa Dam, which is located just adjacent to Atchiza Project, is the main source of clean energy not only for Mozambique domestic market, but also for the majority of Sub-Saharan countries. All of these natural resources require good practice of Environmental sustainability in mining activities.

The exploitation of natural resources lays the foundation for the economic and social development, but also is the root cause of various environmental issues. The study aims to analyze the process of natural resource exploitation, to optimize the extraction and utilization processes, maximizing their economic and social values while reducing the accompanied negative environmental impacts. This dissertation focuses on the impacts of exploitation of mineral and hydrocarbon resources in emerging countries on global warming effect, economy and society. Chapter 2 of the dissertation analyzes the life cycle GHG emissions associated with iron ore mining and processing in China. With rapid economic development and nationwide urbanization, the iron ore demand grows while the ore grade declines significantly, leading to the increasing GHG emissions from iron ore production. Results of the research show that the mean life-cycle GHG emissions for Chinese iron ore production are 270 kg CO2e/tonne, with a 90% confidence interval of 210 to 380 kg CO2e/tonne. The two largest contributors to overall GHG emissions are agglomeration (60%) and ore processing (23%). Iron content (ore grade) varies from 15% to 60% and is the largest contributor (40%) to the uncertainty of the results. Chapter 3 explores the impact of China’s outsourcing of iron resources on the global warming effect. This chapter applies the same life cycle assessment framework of Chinese iron ore in Chapter 2 to Australian and Brazilian ore production, and compares the LCA results of Australian and Brazilian ore to Chinese iron ore. Results show that among the three iron ore sources, Australian iron ore is the optimal choice for reducing GHG emissions. The mean life cycle GHG emissions of Australian iron ore fines is 60% less than that of Chinese iron ore fines (42 kg CO2e/tonne versus 110 kg CO2e/tonne). There is no significant difference between the imported iron ores sourced from Brazil versus the China’s domestic supplied iron ores, but if Chinese ore grade falls below 20% in the future, Brazilian iron ores would be preferred. The largest source of GHG emissions for Australian and Brazilian iron ores comes from ocean shipping (accounts for 58% and 75% of the overall GHG emissions respectively). Chapter 4 studies the impacts of the exploitation of pre-salt natural gas in Brazil. Natural gas production and its associated downstream industries are currently underdeveloped in Brazil, while the on-going exploitation of deep-sea pre-salt reservoir would potentially change the current situation. This study analyzes the impacts of the increasing pre-salt gas production and potential natural gas use pathways in downstream industries. Results reveal that GHG emissions associated with pre-salt gas production vary according to the stage of reservoir exploitation. At the early stage, the estimate of GHG emissions is 5.4 (90%CI: 4.5~6.4) gCO2e/MJ, and the value becomes 7.1 (90% CI: 6.3~8.0) gCO2e/MJ for the intermediate stage. All six natural gas use pathways analyzed in the study emit less GHG on average than their current corresponding incumbent pathways. The mean GHG emissions reduction from natural gas use for power generation, nitrogen fertilizer production, methanol production, as the reducing agent for steel making, ethylene-based polymer production, heavy-duty vehicle fueling are estimated to be 0.83, 2.3, 0.38, 35, 2.6 and 0.078 million tonnes CO2 equivalent per year, respectively. The specific economic profits of the six pathways are affected by the prices of natural gas and traditional fuel. Under current fuel prices, the net annual profits for the six pathways are -270, 87, 92, 1700, 190 and -1500 million dollars, respectively. The job creation potential from the pathways of power generation, nitrogen fertilizer production, methanol production and as reducing agent for steel production are estimated to be 28, 17, 5 and 36 thousand, respectively.

The present work focuses on mineral reactions and slag formation of LKAB olivine iron ore pellets (MPBO) subjected to reducing conditions in the LKAB experimental blast furnace (EBF). The emphasis is on olivine reactions with surrounding iron oxides. Many factors influence the olivine behaviour. The study was performed by use of micro methods; optical microscopy, micro probe analysis, micro Raman and Mössbuer spectroscopy and thremodynamic modeling. During manufacturing, in oxidising atmosphere at high temperature (1350°C), olivine alterations occur through slag formation and rim reactions with iron oxides and other additives. To be able to describe olivine behaviour in the rather complex blast furnace reduction process one has to consider factors such as reactions kinetics, reduction degree of iron oxides, vertical and horizontal position in the furnace and reactions with alkali. Samples were collected from the EBF both from in shaft probing during operation and from excavation following quenching of the EBF. The initial slag forming olivine consist of primary forsterite – (Mg1.9Fe0.1)SiO4 – with inclusions of hematite and an amorphous silica rich phase, a first corona with lamellae of magnesioferrite, olivine and orthopyroxene, a second corona of amorphous silica and magnesioferrite. During reduction in the upper shaft in the EBF (700-900°C) Fe3+ reduces to Fe2+. The amorphous silica in the second corona absorbs alkali, Al, Fe2+, Mg, and Ca and form glasses of varying compositions. The lamellae in the first corona will merge into a single phase olivine rim. With further reduction the glasses in the second corona will merge with the olivine rim forming an iron rich olivine rim and leaving the elements that do not fit into the olivine crystal lattice as small silicate glass inclusions. Diffusion of magnesium and iron between olivines and iron oxides increase with increasing temperature in the lower shaft of the EBF (750-1100°C). In the cohesive zone of the EBF (1100-1200°C) Fe2+ is not stable any longer and Fe2+ will be expelled from the olivine as metallic iron blebs, and the olivine will form a complex melt with a typical composition of alkali-Al2O3-MgO-SiO2. Alkali plays an important role in this final olivine consumption. The quench time for samples collected with probes and excavation are minutes respectively hours. A study of the quench rate’s effect on the phases showed no differences in the upper shaft. However, in the lower shaft wüstite separates into wüstite and magnetite when wüstite grows out of its stability field during slow cooling of excavated samples. There is also a higher alkali and aluminium deposition in the glass phases surrounding olivines in excavated pellets as a result of alkali and aluminium gas condensing on the burden in the EBF during cooling. Coating applied to olivine pellets was studied in the EBF with the aim to investigate its behaviour, particularly its ability to capture alkali. The coating materials were kaolinite, bauxite, olivine and limestone. No significant reactions were observed in the upper shaft. In the lower shaft a majority of the phases were amorphous and reflecting the original coating compositions. Deposition from the EBF gas phase occurs and kalsilite (KAlSiO4) is found in all samples; coating used for binding alkali is redundant from a quality perspective.

The objectives of this project were to survey the flotation circuit of the Boliden concentrator, mass balance collected data and evaluate a scale-up model for laboratory flotation results. The model assumes that half of the recovery to cleaner middlings in a standard laboratory test would report to the final concentrate if it were done in closed circuit, as is the case in a full-scale plant. It has been used by Boliden Mineral AB since 1982 but its accuracy had not been studied since 1986. The model can be categorised as of open circuit type with scale-up factors. The project was based on a complex Ag-Au-Cu-Pb-Zn sulphide ore from the Kristineberg mine. Laboratory tests were done to produce concentrates of CuPb, Cu, Pb and Zn with pulp samples from the concentrator as feed material. The software HSC 9.3 was used to mass balance data from the plant survey. It was decided that the model would be deemed usable if it was able to predict the plant results with the same accuracy as in the survey of 1986. A simulated locked cycle test with split factors (Agar &amp; Kipkie, 1978) was identified as an alternative scale-up model. The results showed that the model was able to predict the plant results with the same accuracy as in 1986. It was especially good at predicting grade and recovery of the main element in a concentrate. For example, it predicted an 18 % higher grade and 11 % lower recovery of Cu to the CuPb concentrate, while a 3 % lower grade and 11 % lower recovery of Zn was predicted to the Zn concentrate. The locked cycle model gave much worse predictions on grades, but more accurate recoveries. It was also better at predicting the behaviour of minor impurity elements such as As and Bi. A recommendation is to combine the two alternatives in a type of "mixed cycle" model. In this study, it would have predicted an 18 % higher grade and 7 % lower recovery of Cu to the CuPb concentrate, as well as a 3 % lower grade and 1 % higher recovery of Zn to the Zn concentrate compared with plant results. Such a model seems to give better figures, but should be put to the test on more samples and ores to confirm this belief. It could at the very least be used to check the reliability of results predicted by the current scale-up model.<br>Syftet med det här examensarbetet var att utföra en detaljprovtagning av flotationskretsen i Bolidens anrikningsverk, massbalansera data och sedan utvärdera en modell för uppskalning av resultat från laboratorieflotationer. Modellen antar att hälften av utbytet till returgodset i ett satsvis laboratorieförsök skulle rapportera till det slutliga koncentratet om det återcirkulerades, såsom i ett anrikningsverk. Den har använts av Boliden Mineral AB sedan 1982 men utvärderades senast 1986. Kategoriskt kan den ses som en uppskalningsmodell av typen öppen krets med skalfaktorer. Projektet baserades på en komplex Ag-Au-Cu-Pb-Zn sulfidmalm från gruvan i Kristineberg. Laboratorieförsök utfördes för att ta fram koncentrat av CuPb, Cu, Pb och Zn, med pulpprover från driften som utgångsmaterial. Programmet HSC 9.3 användes för att massbalansera datan från provtagningen. Det bestämdes att modellen skulle anses som godtagbar ifall den kunde förutspå driftresultatet med samma noggrannhet som 1986. Ett simulerat försök av typen sluten krets (Agar &amp; Kipkie, 1978) identifierades som den mest intressanta alternativmodellen och även den utvärderades. Resultaten visade att modellen än idag ger godtagbara förutsägelser med samma noggrannhet som 1986. Modellen var särskilt bra på att förutspå halt och utbyte av den huvudsakliga metallen till dess eget koncentrat. Den förutspådde exempelvis en 18 % högre halt och 11 % lägre utbyte av Cu till CuPb-koncentratet, samt 3 % lägre halt och 11 % lägre utbyte av Zn till Zn-koncentratet. Den alternativa modellen gav sämre förutsägelser med avseende på halter, men bättre med avseende på utbyten. Den var bättre på att förutspå beteendet hos låghaltiga föroreningar såsom As och Bi. Rekommendationen är att kombinera de två modellerna till en "blandkretsmodell". I den här undersökningen hade ett sådant alternativ förutspått en 18 % högre halt och 7 % lägre utbyte av Cu till CuPb-koncentratet, samt 3 % lägre halt och 1 % högre utbyte av Zn till Zn-koncentratet jämfört med driftresultatet. En sådan modell tycks ge bättre förutsägelser, men bör testas på fler prover och malmtyper. Den borde åtminstone kunna användas för att kontrollera trovärdigheten hos resultaten förutspådda av den nuvarande modellen.

Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2010.<br>ENGLISH ABSTRACT: Previous work has shown that microwave heating of mineral ores induces micro cracks within the ore structure, which can be attributed to the difference in the adsorption of microwaves amongst the different mineral phases. This reduces the energy required during subsequent grinding and enhances the liberation of valuable minerals. In order to design microwave applicators for this purpose, knowledge of the effective dielectric properties of the crushed ore is required. Of particular interest is the effective complex permittivity of the bulk crushed ore. The measurement of the effective permittivity of a large volume of crushed ore is most readily accomplished using the waveguide measurement technique. In this method a representative sample of the material is placed in a defined and fixed volume in a standard size rectangular section metallic waveguide. The magnitude and phase angle of the transmitted and reflected low power microwaves through and from the sample are measured. The complex permittivity can be extracted from these so-called scattering, or Sij parameters. In this study the effective complex permittivities for two porphyry copper ores and a copper carbonatite ore were determined as a function of particle size distribution (-26.5+2mm) using two sizes of waveguide (WR284 and WR340). The sample holders incorporate dielectric windows for the location of the material under test. The extraction of dielectric properties from Sij parameter measurements is problematic using standard algorithms in such cases. Accordingly a new Database Extraction (DBE) Algorithm has been developed. In this method, a database of scattering parameters is established through electromagnetic modelling of the measurement system. A search algorithm is used to determine the effective complex permittivity of the modelled load whose scattering parameters provide the best fit to the experimental data. The goodness of the experimental fit of the simulated to the measured Sij parameters is determined by a root mean squared deviation minimisation metric. Results show that the method can be used successfully to determine an effective complex permittivity for a bulk volume of the crushed material. It is concluded that the dielectric property extraction over the full operational frequency interval (2.3-3 GHz) is preferred as it has a larger degree of extraction confidence and hence reliability. Results show that with increasing particle size, the experimental fit between the simulated and measured Sij parameters becomes increasingly poor, as wall effect become more prominent. The effect is most prominent for the smaller WR284 waveguide size. It is shown that for a waveguide size of similar size to the particle size, the Sij parameter fitting is poorer compared to when a larger waveguide size is used. The extracted complex permittivity reproducibility between repeated dielectric property measurements is improved for the WR340 waveguide size, as the extractions in the WR284 waveguide is dominated by the combined particle size and wall-effects of the sample holder. Ore mineralogy is identified as a key parameter that influences the dielectric properties of the crushed ore. For ores with a dominant microwave absorbent mineral phase, the dielectric constant and loss factor is found to be larger, compared with ores with a more dominant microwave transparent gangue mineral phase.<br>AFRIKAANSE OPSOMMING: Navorsing toon dat die verhitting van mineraal erts, met mikrogolwe, mikroskaal frakture in die mineraalstruktuur teweeg bring weens die verskil in die adsorpsie van mikrogolwe in die verskillende mineraalfases. Gevolglik verminder die energievereiste vir die vergruising van die erts en verbeter die vrystelling van waardevolle minerale wat vasgevang is in die mineraalmatriks. Vir die ontwerp van mikrogolfapplikators vir dié doel, word die effektiewe diëlektriese eienskappe van die vergruisde erts benodig. Van spesifieke belang is die effektiewe komplekse permittiwiteit van die erts. Die effektiewe permittiwiteit van `n vergruisde materiaal monster word met behulp van die golfgeleier tegniek gemeet. Vir dié tegniek word `n verteenwoordigende monster van die materiaal in `n rigiede volume in `n standaard grootte reghoekige golfgeleier geplaas. Die grootte en fasehoek komponente van die deurgelate en weerkaatste mikrogolwe deur en van die oppervlak van die materiaal word gemeet. Die komplekse permittiwiteit van die vergruisde materiaal kan geëkstrakteer word vanaf hierdie sogenaamde verspreide, of Sij parameters. In hierdie studie word die effektiewe permitiwiteit van twee porforie koper ertse en `n koper karbonatiet erts bepaal as funksie van partikel grootte (-26.5+2 mm) deur gebruik te maak van twee standaard grootte golfgeleiers. Die monster houers inkorporeer diëlektriese vensters om die vergruisde materiaal monster in posisie te hou. In so `n geval is die ekstraksie van die diëlektriese eienskappe vanuit die Sij parameter metings problematies. Gevolglik is ‘n nuwe Databasis Ekstraksie Algoritme ontwikkel wat `n databasis van verspreide parameters opstel deur die elektromagnetiese simulasie van die metingsisteem. `n Soek-algoritme word gebruik om die effektiewe komplekse permitiwiteit van die gesimuleerde monster te bepaal wat die beste ooreenstem met dié van die gemete eksperimentele Sij parameter data. Die mate van ooreenstemming tussen die parameters, word bepaal aan die hand van die minimaliserings prosedure. Resultate toon dat dié metode geskik is vir die bepaling van die effektiewe komplekse permitiwiteit van die vergruisde monster. Dit word vasgestel dat die betroubaarheid van die geëkstraeerde Sij parameters, en gevolglik die diëlektriese eienskappe van die erts, toeneem indien die algoritme oor `n groter frekwensie band uitgevoer word. Resultate toon verder dat met toenemende partikel grootte, die mate waartoe die absolute grootte en fasehoek komponente van die gesimuleerde en gemete Sij parameters ooreenstem, versleg. Dit word toegeskryf aan wand-effekte. Hierdie verskynsel is veral opmerklik vir die kleiner grootte golfgeleier. Dit word getoon dat vir metings waar die golfgeleier dieselfde orde grootte geometriese afmetings het as die vergruisde erts self, die passing tussen die gesimuleerde en gemete Sij parameters swakker is, wanneer dit vergelyk word met metings waar dit nie die geval is nie. Die reproduseerbaarheid van die geëkstraeerde diëlektriese eienskap waardes verbeter vir lesings wat uitgevoer word in `n groter grootte golfgeleier. Laasgenoemde word toegeskryf aan die meer dominante wand-effekte wat kenmerklik is vir `n kleiner golfgeleier. Erts mineralogie word geïdentifiseer as `n sleutel parameter wat die diëlektriese eienskappe van die vergruisde materiaal beïnvloed. Beide die diëlektriese konstante en verliesfaktor is groter vir ertse met `n oorheersende mikrogolf absorberende mineraalfase.

Thesis (MEng)--Stellenbosch University, 2000.<br>ENGLISH ABSTRACT: A desire to increase the efficiency of the comminution process in mineral process systems has led to the need of determining the size distribution of ore particles at various stages in the system. The objective of this research is to investigate the feasibility of the use of an acoustic sensor for measuring particle size distribution. The acoustic signal generated when the particles impact on a cantilever bar is analysed using digital signal processing techniques. As rocks fall onto a metal bar, the bar vibrates. The vibrations contain information th a t is extracted to determine the size of particles tha t impacted on the bar. The bar is modelled as a linear system which is excited by impulses (impact of particles). The response of the bar is deconvolved from the acoustic signal to obtain an impulse whose amplitude is proportional to the energy of the impact. In order to improve size estimates, deconvolution is performed using a statistical model of the impulse sequence (Bernoulli-Gaussian) and then estimated using MAP estimation. Size estimates are not only a function of the mass of particles, but also on the exact position of impact on the bar. Since there is always a variation in the position of impact, size estimates are erroneous. It was found that the position of impact can be determined as to reduce variances dramatically. Due to physical sampling in space, the sensor has a bias towards larger particles. We show how this can be represented mathematically and removed. This project is mainly concerned with rocks in the +8-25mm (+0,7-22 gram) size range.<br>AFRIKAANSE OPSOMMING: Vergruising van erts in die mineraalbedryf verg groot hoeveelhede energie. Daar is ’n behoefte gei'dentifiseer orn hierdie proses meer effektief te maak. Aangesien die effektiwiteit van ’n meul ’n funksie is van die ertsgroottes wat gemaal word, kan partikel grootte inligting aangewend word om effektiwiteit te bevorder. Die doel van hierdie tesis is om die lewensvatbaarheid van ’n akoestiese sensor vir die doel van partikelgrootte estimasie, te ondersoek. Erts partikels wat val vanaf ’n vervoerband op ’n kantelbalk, veroorsaak dat die balk vibreer. Deur hierdie vibrasies te meet en verwerk, kan inligting aangaande partikel grootte verkry word. Die stelsel word gemodelleer as ’n lineere sisteem met impulse as intree. Die geobserveerde sein is die konvolusie tussen die intree impulse en die impulsweergawe van die sisteem. Deur gebruik te maak van ’n statistiese model en MAP-estimasie, word die effek van die sisteem gedekonvuleer vanaf die geobserveerde sein om ’n benadering van die intree impuls sein te verkry. Die amplitudes van die impulse word gebruik as ’n aanduiding van partikel massa. Partikelgroottes soos benader deur die stelsel, is ’n funksie van die die posisie waar die partikel die balk tref. Deur van patroonherkenning tegnieke gebruik te maak, word die posisie van impak bepaal om sodoende grootte benaderings aan te pas en die variansie van grootte verspreidings te verminder. As gevolg van die feit dat partikels gemonster word deurdat slegs ’n klein persentasie van die hele omvang van partikels ondersoek word, onstaan daar ’n oorhelling ( “bias” ) na groter partikels. Die kans dat groter partikels die balk tref is groter as vir klein partikels. ’n Wiskundige model vir hierdie verskynsel word voorgestel en gewys hoe die die oorhelling geneutraliseer kan word. Hierdie projek het te doen met ertsgroottes +8-25mm (+0,7-22 gram).

ABSTRACT PRODUCTION OF HEAVY-MEDIA-QUALITY MAGNETITE CONCENTRATE FROM KESiKK&Ouml<br>PR&Uuml<br>IRON ORE TAILINGS G&uuml<br>ng&ouml<br>r, Kazim M. Sc. Department of Mining Engineering Supervisor: Prof. Dr. M. &Uuml<br>mit Atalay May 2010, 91 pages The aim of this research was to investigate the possibility of the production of a magnetite concentrate which is suitable for preparation of heavy media from iron ore tailings of G&uuml<br>ncem Mining Company magnetic separation facility. During the study, three different tailings named as low grade, medium grade and high grade with 5.91 % Fe3O4, 19.06 % Fe3O4 and 37.06 % Fe3O4, respectively, were used. Mineralogical analyses of test samples showed that magnetite and hematite were the major ore minerals while pyrite and chalcopyrite were found in trace amounts. Actimolite, tremolite, epidote, chlorite, quartz, calcite, and dolomite were the gangue minerals. The effects of feed particle size and applied magnetic field intensity on the Fe3O4 grade and recovery of concentrate were examined throughout magnetic concentration tests. The highest grade magnetite concentrate with 79.98% Fe3O4 content was obtained with 65.42% recovery from 100% -75 micron size feed at 1000 Gauss magnetic field intensity from high grade tailing.

Zinkgruvan is a Pb-Zn-Ag deposit located in south-central Sweden, owned and operated by Lundin Mining. The ore is beneficiated by a collective-selective flotation circuit, recovering both galena and sphalerite in a bulk rougher-scavenger flotation stage and later on separating them into two final products. Opportunities for increase in zinc recovery in the bulk rougher scavenger flotation stage have been identified as the plant is relying on natural Pb-activation to process the ore. Process mineralogical tools were used to characterize four different orebodies from Zinkgruvan (Burkland, Borta Bakom, Nygruvan and Sävsjön) and evaluate the metallurgical performance for flotation and magnetic separation, following a geometallurgical approach to better understand and predict the behavior of such ore types in processing plant. The first hypothesis in this thesis is that by addition of copper sulfate and increased collector dosage, Zn recovery will be improved without being detrimental to galena flotation. Results demonstrated that there is a significant increase in Zn recovery by further increasing collector dosage and copper-activating the flotation pulp in the scavenger stage. For instance, an increase in zinc recovery up to 16% has been achieved after addition of copper sulfate. Galena is readily floatable while sphalerite takes longer to be recovered. In addition, iron sulfides take longer to be recovered and, after addition of copper sulfate, there was an increase in iron sulfide recovery. The amount of iron sulfides reporting to the concentrate should still not be a problem to the plant. Most of the Fe in the concentrate is still coming from the sphalerite lattice. However, it might be that some orebodies coming into production in the near future have higher amounts of pyrrhotite, which might be a problem. Therefore, magnetic separation methods have been tested to remove pyrrhotite from the bulk ore. The second hypothesis is that the high Fe content in the concentrate might be due to the presence of iron sulfides, in which case they could be selectively removed by magnetic separation. XRD analyses demonstrated that Sävsjön is a highly variable orebody, and that its high Fe content varies with the location inside the orebody, being caused by either iron sulfide or iron oxide minerals. Both monoclinic and hexagonal pyrrhotite have been observed. Davis Tube could remove monoclinic pyrrhotite but it was very inefficient when dealing with hexagonal pyrrhotite. WHIMS, on the other hand, performed well for both types of pyrrhotite. When applying Davis Tube on Sävsjön OLD feed, a concentrate with up to 52.3% pyrrhotite is achieved, at a recovery of 35.32%. However, sphalerite is also reporting to the magnetic concentrate, which would generate Zn losses for the overall process. Zinc losses were up to 15.3% when the highest field strength was applied. Therefore, the applicability of magnetic separation for Zinkgruvan ore must be further evaluated.

Dilution and ore recovery/loss have an important role in calculation of mineral reserves. Each percent increase in dilution and decrease in recovery negatively affects economic value of the reserve. These parameters are mainly controlled by the quality of the mine design and stoping practice. This study provides an approach developed for dilution and recovery/ore loss calculations. The contribution of mine design software (MineSight) and the recent survey technique called Cavity Monitoring System (CMS) were presented in this study. The purpose was to compare the new approach with the old system where the calculations had been done according to some assumptions and to optimize mineral reserve estimation process. Results indicate that the new approach used in reserve estimation process gives ~1.6% closer tonnages to the actual numbers and the grades are both ~1.6% closer to the actual values numbers when compared with the old system.

Froth flotation is a physicochemical process that enables the separation of valuable minerals and unwanted gangue minerals contained in an ore. It utilises the differences in surface properties of the minerals to be separated. Among other factors affecting flotation, water is a major factor as it acts as a reagent and transport medium. Therefore, it stands to reason that the quality of the water used in the process matters. Current environmental restrictions on water usage which are aimed at addressing the global scarcity of water require that mining operations recycle and reuse water within their operations. This necessitates proactive management strategies and initiatives aimed at understanding the impact that water could have on flotation and other water intensive processes. The development of such initiatives relies on the provision of sound and fundamental scientific evidence examining and decoupling the effects of water quality on the sub-processes of flotation. This would enable the creation of alternative operating conditions at which flotation could still occur without significant effects on production and profitability. Recycling of process water has for many years been the mining industry’s solution to reducing reliance on municipal water because mining operations are often located in arid regions. It has become clear that the recirculation of water in flotation circuits results in the accumulation of dissolved solids, electrolytes, unspent reagents and biological matter possibly resulting in poor flotation performance or alternatively high costs associated with water treatment. Given that water is both a reagent and transport medium in flotation, changes in its quality can significantly affect flotation performance through electrolyte-reagent-mineral interactions. This study has investigated whether there are any dominant or synergistic electrolyte-reagent interactions occurring during flotation which may impact negatively on the flotation performance. Interactions occurring in both the pulp phase and the froth phase were investigated through established bench scale flotation techniques. On the basis of available literature, investigations were carried out to identify inorganic electrolytes which had the biggest impact on froth stability as well as those which had a dominant role on depression, and specifically CMC efficacy on gangue management. A Merensky ore, typical of the South African Bushveld Igneous Complex was selected as previous work within the Centre for Minerals Research was conducted on ores of similar mineralogy. Threephase bench scale flotation and froth column tests were performed to examine the effect of increasing ionic strength of plant water and CMC dosage on froth stability and gangue recovery. Two-phase batch flotation and froth column tests were performed at various electrolytic conditions to assess the effect of ionic strength, electrolyte type and pH on froth stability using water recovery, foam height and foam collapse time as key performance indicators of froth stability. Settling tests, adsorption studies, zeta potential measurements as well as inorganic electrolyte speciation determination were considered in order to elucidate the role of water quality on gangue depression. Talc and pyrrhotite were selected as proxies for naturally floatable gangue (NFG) and sulphides respectively in order to simulate the possible behaviour of a Merensky ore. Increasing the ionic strength resulted in increased solids and water recoveries suggesting an enhancement in froth stability. When the effect of ionic strength on CMC behaviour was investigated under changing pH, results showed that contrary to findings at pH 9 which showed increases in solids recovery with increasing ionic strength, solids recovered decreased with increasing ionic strength at pH 11. This suggested that at higher pH levels above pH 10 there are hydroxy species present which inhibit the floatability of mineral particles either by forming layers on the mineral particles which hinder the action of the collector or through depressant efficacy enhancement. The speciation diagrams indicated that beyond pH 10, species such as CaOH+ increased in concentration especially at the higher ionic strength. Furthermore the zeta potential results for talc and pyrrhotite showed that at pH 11, the potentials were less negative compared to pH 9 for all synthetic plant waters proving that at pH 11 the pulp chemistry would exhibit a more depressive nature onto mineral particles owing to increased concentrations of positively charged hydroxo species at pH 11 compared to pH 9. These hydroxy species such as CaOH+ would adsorb onto the negatively charged mineral particle, reducing the negative surface charge of the mineral particle. Water recoveries increased with increasing ionic strength at both pH 9 and pH 11. These findings were further supported by 2-phase froth column tests in which water recoveries, foam height, and foam collapse time increased with increasing ionic strengths. This increase in froth stability with increasing ionic strength at both pH conditions is attributed to an increase in the [Ca2+], [Mg2+] and [SO4 2- ] which reduces bubble coalescence. Upon the determination of NFG recovery, entrained gangue recovery and total gangue recovery, it became clear that, at increasing ionic strength, there was a decrease in the recovery of NFG and entrained gangue per g of water recovered. The decrease in the recovery of NFG and entrained gangue per unit water was attributed to the coagulative nature of gangue in the presence of highly concentrated electrolytes and CMC. The fact that total NFG recovery did not change with water quality at a fixed CMC dosage but decreased with increasing ionic CMC dosage is indicative of the strong susceptibility of NFG depression to CMC dosage to an extent that at hyper dosages such as 500 g/t, all NFG is depressed completely. However, given the relationship between solids entrained and water recovery, the total recovery of entrained gangue increased with increasing ionic strength due to increased volumes of water which reported to the concentrate at increasing ionic strength. It was also shown that there was no change in sulphide recovery with increasing ionic strength. This was indicative of preferential adsorption of CMC onto gangue at the conditions tested. Higher solids recoveries or mass pulls were largely due to increased gangue recovery, mainly entrained gangue, which increased with increasing ionic strength. It was thus postulated that at increased ionic strengths, CMC coagulated gangue particles whilst indirectly destabilising the froth and retarding the action of electrolytes on froth stability through the removal of froth stabilising NFG. In order to examine coagulation at increasing ionic strengths, settling tests were performed on a Merensky ore and on pure talc. The results showed reduced settling time with increasing ionic strength and increasing CMC dosage suggesting that in a flotation cell, highly concentrated electrolytes would assist in depression by enhancing the coagulation of gangue and thereby decreasing their floatability. This can be attributed to increased concentrations of Ca2+ and CaOH+ which adsorb onto gangue; adsorption of which is the mechanism through which the chemisorption of CMC onto gangue occurs. In considering the effect of ionic strength and CMC dosage on froth stability, three phase froth column test results showed that the froth collapse time and froth height increased with increasing ionic strength due to an increase in the concentration of inorganic electrolytes which inhibit the coalescence of bubbles. In fact, Ca2+, Cl- , Mg2+, Na+, NO3 - and SO4 2- , which are present in the tested synthetic plant waters, are all reported in literature to have the ability to retard bubble coalescence, thus additive interactive effects in the tested systems should have been present. It was further shown that the addition of CMC resulted in a froth destabilization. The coagulation findings suggested that the presence of inorganic electrolytes enhanced the adsorption of CMC onto gangue due to changes on the mineral surface charge imposed by inorganic electrolytes. Microflotation results in the presence of CMC showed a decrease in the recovery of talc with increasing ionic strength whilst the presence of CMC did not affect the flotation behaviour of pyrrhotite. The adsorption results agreed with the microflotation results and the coagulation findings in that there was less residual CMC, meaning that more CMC was adsorbed onto the mineral surface with increasing ionic strength of plant water. In line with these findings, it was shown that the zeta potential of minerals, both talc and pyrrhotite, although investigated separately, increased (i.e. became less negative) with increasing ionic strengths. Thus, this work showed that increasing the ionic strength of plant water increased the concentration of inorganic electrolytes present in process water which acted on the mineral surface, passivating the mineral surface as seen through the less negative zeta potential in high ionic strengths. This would in turn create an environment conducive for an acid-base interaction between the hydroxyl species coated mineral particles (base) and highly negatively charged CMC ligand (acid), enhancing the preferential adsorption of CMC onto gangue as shown by the increase in the absorbed CMC concentration onto talc. The increased CMC adsorption would consequently assist in the formation of CMC-gangue mineral flocs with an induced coagulative and hydrophilic nature as shown by the shorter settling time in increasing ionic strength. Further investigations were carried out with single salts of cations and anions common in process water in order to identify whether there were any ions with the greatest froth stabilising action and gangue depression; Although Sulphide recoveries did not change with specific ions, the sulphide grades were affected by ion type owing to changes in gangue recoveries. Sulphide grades were higher with divalent ions compared to monovalent ions. It was also shown that salts containing NO3 - resulted in the lowest froth stability, as indicated by water recoveries and froth collapse time, compared to those which contained SO4 2- and Clin solution. Ca2+ and SO4 2- resulted in the highest froth stability compared to Na+. This can be attributed to a better inhibition of bubble coalescence in divalent ions compared to monovalent ions. The divalent Ca2+ and Mg2+ resulted in the lowest gangue recoveries compared to the monovalent Na+.NO3 - resulted in the least gangue recoveries compared to SO4 2- and Cl- . These findings suggested an enhanced hydrophilic nature onto gangue by divalent cations than monovalent cations with an even greater impact in NO3 - containing solutions- . Similarly, coagulation measurements showed an enhanced coagulation in NO3 - compared to SO4 2- with greater coagulation achieved in Ca2+ compared to Na+. An increase in the order of Ca(NO3)2>CaSO4>NaNO3>Na2SO4 in the zeta potential of talc and pyrrhotite was seen. This supported the enhanced coagulation and depression in Ca2+ and NO3 - containing systems. Thus, the findings of this work offer an opportunity to better understand water quality effects on flotation and their implications on froth stability and gangue management. Also, it has been shown that specific ion effects on froth stability and gangue management exist. Overall this study has shown that bench scale flotation techniques such as batch flotation, froth column flotation and microflotation can be used to understand the effect that water quality can have on a specific ore or mineral and that such techniques can be complemented with established surface chemistry laboratory techniques such as adsorption, coagulation and zeta potential to understand the interactions occurring in the air-water, air-solids and solids-water interfaces responsible for a particular flotation performance.. Through lower gangue recoveries, improved coagulation, increased adsorption and zeta potential, it can be concluded that the divalent Ca2+ is most likely to improve gangue depression and even more so in the presence of CMC compared to monovalent Na+. Moreover due to its causing a reduction of bubble coalescence, Ca2+ could result in improved froth stabilities and less entrainment. The monovalent Na+ showed higher gangue recoveries but lower water recoveries due to its weaker froth stabilising action compared to the divalent Ca2+. The higher gangue recoveries could be attributed to entrainment, meaning that given the lower froth stabilising action, Na+ richer solutions are most likely to lead to higher entrainment of gangue. Through higher water recoveries and higher froth collapse time results, it has been shown that SO4 2- ions result in better froth stabilities compared to Cl- and NO3 - ions, and would thus need to be monitored carefully for the desired froth stability. Thus, this work demonstrated the role of inorganic electrolytes on CMC efficacy and gangue depression using adsorption, coagulation and zeta potential results. These results correlated well with this study’s batch flotation and microflotation results. Also, these showed evidence to the suggestions and deductions drawn out of the bench scale flotation results on the effects and mechanisms through which inorganic electrolytes affect gangue and froth stability. This study also demonstrated that the divalent Ca2+ had the greatest froth stabilising effect and the greatest depressive effect on gangue compared to the monovalent Na+. Moreover, it provided evidence suggesting that solutions containing NO3 - were depressive on gangue and less froth stabilising compared to SO4 2- and Cl- . Findings of this work showed experimental evidence of the nature of CMC-electrolyte interaction in the pulp phase and its implications on the froth phase and gangue depression. It is believed that findings of this work offer an opportunity for flotation operations to tailor or control their water quality towards a desired flotation outcome. It may be possible that in order to combat changes in water quality, should closed water cycles be implemented, an operation could adjust their reagent suite to obtain a manageable grade and recovery and alleviate the high cost associated with cleaning of on-site water.

A geometallurgical model is the combination of a spatial model representing an ore deposit and a process model representing the comminution and concentration steps in beneficiation. The process model itself usually consists of several unit models. Each of these unit models operates at a given level of detail in material characterization - from bulk chemical elements, elements by size, bulk minerals and minerals by size to the liberation level that introduces particles as the basic entity for simulation (Paper 1). In current state-of-the-art process simulation, few unit models are defined at the particle level because these models are complex to design at a more fundamental level of detail, liberation data is hard to measure accurately and large computational power is required to process the many particles in a flow sheet. Computational cost is a consequence of the intrinsic complexity of the unit models. Mineral liberation data depends on the quality of the sampling and the polishing, the settings and stability of the instrument and the processing of the data. This study introduces new tools to simulate a population of mineral particles based on intrinsic characteristics of the feed ore. Features are extracted at the meso-textural level (drill cores) (Paper 2), put in relation to their micro-textures before breakage and after breakage (Paper 3). The result is a population of mineral particles stored in a file format compatible to import into process simulation software. The results show that the approach is relevant and can be generalized towards new characterization methods. The theory of image representation, analysis and ore texture simulation is briefly introduced and linked to 1-point, 2-point, and multiple-point methods from spatial statistics. A breakage mechanism is presented as a cellular automaton. Experimental data and examples are taken from a copper-gold deposit with a chalcopyrite flotation circuit, an iron ore deposit with a magnetic separation process. This study is covering a part of a larger research program, PREP (Primary resource efficiency by enhanced prediction).<br>PREP

This thesis focuses on the different degradation mechanisms of the stainless steel in a travelling grate in a Grate-Kiln iron ore pellet indurator. The travelling grate is a conveyor belt that transports green-body pellets to a rotary kiln while the pellets are being dried and pre-heated to a temperature of 900-1100 °C by recycled hot air. After unloading of the pellets to the rotary-kiln for further sintering, the travelling grate is cooled in room temperature while returning to the loading zone of the wet pellets. The steel was tested during thermal cycling in a test-rig, in order to simulate the influence of thermo mechanical fatigue and oxide spallation. The influence of erosion-deposition was investigated in a modified horizontal industrial combustion kiln at 800 °C, with slag and coal from production used as erosive media and combustion fuel, respectively. The influence of minor alloying additions of Mn, Si and Ti on the microstructure was explored by eight different casted alloy compositions. Isothermal heat treatments were performed at 800 °C during 200 hours on steel immersed in deposits recovered from a travelling grate in production. The three main degradation mechanisms found in this work are thermal spallation, erosion-deposition and deposit induced accelerated corrosion (DIAC). Thermal spallation of the oxide layer is caused by the thermal expansion difference between the oxide and the metal during heating and cooling. It has been found that Ti improves the spallation resistance while Si reduces it. Spallation of deposits is another cause believed to increase the degradation. Erosion-deposition appears due to simultaneous erosion and deposition of particles on the travelling grate that causes erosion or deposition depending on the amount of alkali metals in the environment. The velocity of the particles also influences erosion and deposition in the way that higher velocities increase erosion. DIAC is proposed to form on the travelling grate due to the concentration of chloride- and sulphate containing alkali metals in the deposits.  Other than these major degrading mechanisms, minor degradation mechanisms such as internal oxidation, sigma formation, carburization and sensitization towards inter-granular attack have been found inside the steel during heating. Thermo mechanical fatigue (TMF) causes intergranular cracks in the material of the travelling grate. Casting issues such as micro-segregation have also been addressed in this thesis. A few different ways to improve degradation resistance have been proposed, such as homogenization heat treatments, optimization of process parameters and inhibitor solutions.

The profitability of a mineral deposit can be concluded by the comparison of net present values (NPV) of all revenues and expenditures. In the estimation of NPV of a mineral deposit, many parameters are used. The parameters are uncertain. More accurate and reliable NPV estimation can be done with considering the related uncertainties. This study investigates the probability distributions of uncertain variables in estimation of NPV and evaluation of NPV using Monte Carlo simulation. @Risk 4.5.7 software package is used to apply Monte Carlo simulation method. At the end of the study, all possible net present values and their probabilities are given as a probability distribution. Derek&ouml<br>y copper ore reserve is selected to apply uncertainty assessment in NPV of ore reserves. The reserve is evaluated using both conventional polygonal method and a mining software which is Micromine. The southeastern part of the reserve was selected as a study area because average grade of the reserve is relatively low and the reserve extends to a larger area. At the end of the assessment, NPV of the southeastern part of Derek&ouml<br>y ore reserve was found to be between $77.97&times<br>106 and $318.78&times<br>106 with 68.27% (x&plusmn<br>&amp<br>#963<br>) probability and between &ndash<br>$45.37&times<br>106 and $443.54&times<br>106 with 95.45% probability (x&plusmn<br>2&amp<br>#963<br>).

For future development of automated sensor-based sorting in the mining industry, an improvement in the separation efficiency of the equipment is desirable. This could be achieved through a better understanding of the identification and separation aspects of the automated sorter. For automated sorters that undertake separation through the use of compressed air jets, the problem of poor separation efficiency has been linked with co-deflection losses. Co-deflection losses occur as particles meant to pass on to the ‘accept’ bin are co-deflected with the particles (which are to be deflected) meant to go to the ‘reject’ bin. To study co-deflection losses and suggest means of improving automated sorter separation efficiency, this research investigates the effects of particle size, shape, throughput, together with the proportion of particles (out of the total test batch) required to be deflected on separation efficiency. The effect of the air valve configuration on separation efficiency was also studied. Presented also is a mathematical model which could be used to predict automated sorter separation efficiency. All separation efficiency investigations were undertaken using a TiTech Combisense© (BSM 063) automated sorter. Samples of granite were sized into -20+15mm, -15+10mm and -10+6mm size fractions and grouped into cubic and flaky shape fractions. These fractions were then divided into two with one portion painted for colour separation efficiency investigations. The separation efficiency results confirmed earlier research indicating that particle size and the fraction requiring deflection affects separation efficiency, with separation efficiency decreasing with a decrease in particle size and an increase in throughput. It was observed that co-deflection loss occurs when correctly identified ‘accept’ particles are co-deflected due to their close proximity to ‘reject’ particles that are to be deflected. Observations from the tests indicate that an increase in the proportion of particles requiring deflection increases the probability of finding ‘accept’ particles in close proximity to ‘reject’ particles leading to co-deflections. Monte Carlo simulations were used to produce a random distribution of particles on the conveyor belt as would be obtained from actual investigations. From these simulations particle proximity relationships and particle co-deflections were studied. Results indicate that the Monte Carlo simulations under-predicts particle proximity associations. The effect of shape on co-deflection was investigated with results indicating that flaky shaped particles produce higher number of co-deflections compared to cubic shaped particles. It was also observed that the valve sensitivity determined from valve opening and closing times is of importance to the selectivity (precision) of the separating air jets. A mathematical separation efficiency model is presented which contains two variables, the belt loading (calculated using particle size, shape and throughput) and the particle fraction of the total test batch that are to be deflected (% deflection). The separation efficiency can be calculated once these two variables are determined.

The Skellefte District (SD) is one of the richest metallogenic mining areas in Sweden. The main deposits consist of volcanic-hosted massive sulphides (VHMS) rich in zinc, copper, lead, gold and silver, that have been explored and mined for more than a century. Considering that technological advancements allow deeper mining, and that today new discoveries rarely occur, renewed efforts are now directed at locating targets at greater depths.   Thus, current exploration strategies need to be adapted, and a better understanding of regional scale structures is necessary. To address these questions the project VINNOVA 4D modeling of the Skellefte District was launched. Its main purpose is to unravel the regional structures and tectonic setting of the SD. To accomplish this, new geological and geophysical data have been acquired in two key localities. This thesis presents the contribution from 2D and 3D inversion of magnetotelluric (MT) data and seismic reflection data. The main findings include: conductive hydrothermally altered zones within the otherwise resistive rocks of the Skellefte Group, the depth extension of early and postorogenic intrusions, prominent shear zones in the central part of the district, and enhanced reflectivity and conductivity at the base of the Skellefte Group throughout the SD. Even though the application of these methods is challenged by the complex geological setting of the SD, it is shown that after a careful processing and analysis of the data, they are able to provide a robust image of the deep subsurface. Additionally, the combination of reflection seismics and MT has proved to be a powerful tool for hypothesis testing and to develop the general understanding of the configuration and history of the SD. Furthermore, two 3D inversion models of MT data are presented and compared with the results of standard 2D determinant inversions. The 3D procedure shows significant improvements in data fit and is able to constrain better the observed model features. Although 3D inversion of MT data is not yet a run of the mill scheme and issues like model assessment and galvanic distortion effects need to be further addressed, results from complex environments with areal coverage, are already superior to those from 2D inversions.<br>Skellefteåfälten är ett av de viktigaste malmdistrikten i Sverige. Malmkropparna består av vulkaniskvärda Massiva Sulfider (VHMS) rika på Zink, Koppar, Bly, Guld och Silver, och har utforskats och brutits i mer än ett sekel. Med tanke på att de senaste tekniska framstegen tillåter djupare brytning, och att nya upptäckter är ovanliga idag, riktas nya ansträngningar mot att lokalisera malm på större djup. Aktuella prospekteringsstrategier måste därför anpassas, och en bättre förståelse av regionala strukturer är nödvändig. För att lösa dessa frågor lanserades projektet VINNOVA 4D modeling of the Skellefte District. Dess främsta syfte är att utreda de regionala strukturerna och det tektoniska läget av Skelleftefältet. För att uppnå detta, har nya geologiska och geofysiska data insamlats vid två viktiga platser i distriktet. Denna avhandling presenterar bidrag från inversionsmodellering i 2D och 3D av magnetotelluriska (MT) data samt resultaten av en reflektionsseismisk profil. De viktigaste resultaten är: bra ledande hydrotermiskt förändrade zoner inom de annars resistiva bergarterna i Skellefte-gruppen, djupet till tidiga och postorogeniska intrusioner, framstående skjuvzoner i den centrala delen av området, och ökad reflektionsförmåga och konduktivitet vid basen av Skellefte-gruppen i hela fältet. Även om tillämpningen av dessa metoder utmanas av fältens komplexa geologiska läge, visas det efter en noggrann bearbetning och analys av data att de ger en robust bild av den lite djupare berggrunden. Dessutom har kombinationen av reflektionsseismik och MT visat sig vara ett kraftfullt verktyg för hypotesprövning och för att utveckla den allmänna förståelsen av Skelleftefältet och dess historia. Därutöver presenteras två 3D inversionsmodeller av MT data och jämförs sedan med resultaten från 2D determinantinversioner. 3D tekniker visar betydande förbättringar av datapassform och begränsar observerade anomalier bättre. Även om 3D inversion av MT data ännu inte är en vanlig teknik och frågor som modellbedömning och galvaniska distorsionseffekter måste behandlas ytterligare, är resultat från komplexa miljöer med lagom yttäckning redan överlägsna.<br>VINNOVA 4D modeling of the Skellefte District

The Skellefte ore district in northern Sweden is a Palaeoproterozoic volcanic arc and one of the most important ones hosting volcanogenic massive sulfide (VMS) deposits, producing mainly base metals and orogenic gold deposits. Due to high metal prices and increased difficulties in finding shallow deposits, the exploration for and exploitation of mineral resources is quickly being moved to greater depths. For this reason, a better understanding of the geological structures in 3D down to a few kilometers depth is required as a tool for ore targeting. As exploration and mining go deeper, it becomes more and more evident why a good understanding of geology in 3D at exploration depths, and even greater, is important to optimize both exploration and mining. Following a successful pilot 3D geological modeling project in the western part of the district, the Kristineberg mining area, a new project "VINNOVA 4D modeling of the Skellefte district" was launched in 2008, with the aim of improving the existing models, especially at shallow depth and extending the models to the central district. More than 100 km of reflection seismic (crooked) profiles were acquired, processed and interpreted in conjunction with geological observations and potential field data. Results were used to constrain the 3D geological model of the study area and provided new insights about the geology and mineral potential at depth. Results along the seismic profiles in the Kristineberg mining area proved the capability of the method for imaging reflections associated with mineralization zones in the area, and we could suggest that the Kristineberg mineralization and associated structures dip to the south down to at least a depth of about 2 km. In the central Skellefte area, we were able to correlate main reflections and diffractions with the major faults and shear zones. Cross-dip analysis, reflection modeling, pre-stack time migration, swath 3D processing and finite-difference seismic modeling allowed insights about the origin of some of the observed reflections and in defining the imaging challenges in the associated geological environments.<br>VINNOVA 4D modeling of the Skellefte district

Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2016-12-15T11:54:43Z No. of bitstreams: 2 Dissertação - Débora Nascimento Sousa - 2016.pdf: 4367047 bytes, checksum: 35c38302a78c568610631ef86cddb6c3 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)<br>Approved for entry into archive by Jaqueline Silva (jtas29@gmail.com) on 2016-12-15T17:17:55Z (GMT) No. of bitstreams: 2 Dissertação - Débora Nascimento Sousa - 2016.pdf: 4367047 bytes, checksum: 35c38302a78c568610631ef86cddb6c3 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)<br>Made available in DSpace on 2016-12-15T17:17:55Z (GMT). No. of bitstreams: 2 Dissertação - Débora Nascimento Sousa - 2016.pdf: 4367047 bytes, checksum: 35c38302a78c568610631ef86cddb6c3 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-10-10<br>The depressant used in the iron ore flotation are starches, basically made up of amylose and amylopectin, and the most widely used corn because of its availability and economic viability. The objective was to study the performance of seven starches from different botanical sources in reverse flotation cation of iron ore through Microflotation and flotation test bench cell. We evaluated the influence of different dosage depressants in the buoyancy of the minerals quartz and hematite, the tests used to passing particle size of 180 m and held 75 micrometre (-80 + # 200 #). Any material used in the present study was completely released, ie without the presence of mixed particles. The samples were analyzed chemically and physically by Scanning Electron Microscopy, Energy Dispersive X-ray (EDS) and chemical analysis. In the modified Hallimond tube, we used the following depressants: Conventional corn starch, cassava starch, potato flour, cassava flour HIPIX®100, HIPIX®101 and HIPIX®102, the dosages 400, 800, 1600, 3200 , 4800 and 6400 (g / t) maintaining fixed collector dosage Flotigam EDA Clariant at a dosage of 70 g / t was observed to influence the dosing of depressant tested in floatability of minerals. There was better efficiency in depressant HIPIX®100, HIPIX®101 and cassava starch. In the flotation cell counter, model engendering power was used with 60% hematite and 40% quartz with high purity. is homogenized and the following pre-depressant was tested: Cassava flour, cassava starch, HIPIX®100, HIPIX®101 and normal corn starch (using it as a comparison), the measurements 400, 800 and 1600 (g / t). This single step in flotation cell bench worked as a rougher stage compared to mining companies. The results of Microflotation and flotation bench were statistically analyzed by analysis of variance (ANOVA), checking variation of doses of depressants are factors that influence the recovery of the mineral compared to conventional corn starch. At this stage, the results prove to be technically possible to replace the corn starch in the flotation cation reverse iron ore, apart from replacing the conventional corn starch was noticed that the performance of some starches leads to a lower specific consumption reagent, which can result in economic and environmental gains.<br>Os depressores utilizados na flotação de minério de ferro são os amidos, constituídos basicamente de amilose e amilopectina, sendo o de milho mais utilizado devido à sua disponibilidade e viabilidade econômica. O objetivo do trabalho foi estudar o desempenho de sete amidos provenientes de diferentes fontes botânicas na flotação catiônica reversa de minério de ferro, através de ensaios de microflotação e flotação em célula de bancada. Foram avaliados a influência da dosagem de diferentes depressores na flotabilidade dos minerais de quartzo e hematita, nos testes utilizou-se granulometria passante em 180 µm e retido 75 µm (-80# + 200#). Todo material utilizado no presente trabalho estava totalmente liberado, ou seja, sem presença de partículas mistas. As amostras foram analisados química e fisicamente por meio de Microscopia Eletrônica de Varredura, Energia Dispersiva de Raios-X (EDS) e análises químicas. No tubo de Hallimond modificado, utilizou-se os seguintes depressores: amidos milho convencional, amido de mandioca, féculas de batata, fécula de mandioca, HIPIX®100, HIPIX®101 e HIPIX®102, nas dosagens 400, 800, 1600, 3200, 4800 e 6400 (g/t) mantendo fixa dosagem de coletor Flotigam EDA da Clariant, na dosagem de 70 g/t, observou-se a influência da dosagem dos depressores testados na flotabilidade dos minerais. Observou-se melhor eficiência nos depressores HIPIX®100, HIPIX®101 e fécula de mandioca. Já na célula de flotação de bancada, modelo ENGENDRAR utilizou-se alimentação com 60% de hematita e 40% de quartzo com alta pureza. Homogeneizou-se previamente e testou-se os seguintes depressores: Fécula de mandioca, amido de mandioca, HIPIX®100, HIPIX®101 e amido de milho convencional (utilizando-o como comparação), nas dosagens 400, 800 e 1600 (g/t). Esta única etapa em célula de flotação em bancada funcionou como uma etapa rougher comparado à empresas de mineração. Os resultados da microflotação e da flotação por bancada foram analisados estatisticamente através da análise de variância (ANOVA), verificando se variação das dosagens dos depressores são fatores que influenciaram na recuperação do mineral comparado ao amido de milho convencional. Nesta etapa os resultados mostram-se possibilidades técnicas para a substituição do amido de milho na flotação catiônica reversa de minérios de ferro, além da substituição do amido de milho convencional, percebeu-se que o desempenho de alguns amidos leva a um menor consumo específico de reagente, o que pode acarretar em ganhos econômicos e ambientais.

The Rävliden North deposit (Rävliden N) is a volcanogenic massive sulphide (VMS) deposit in the western part of the Skellefte district, northern Sweden. The district is one of Sweden’s major metallogenic provinces with a significant amount of VMS deposits. The Rävliden N deposit, discovered in 2011, contains copper, zinc, lead, silver and subordinate gold and occurs close to the largest VMS deposit in the district, the Kristineberg deposit, which has been mined for more than 70 years. The purpose of this master thesis is to study the composition, mineralogy and paragenetic relationships in different types of sulphide mineralization from the Rävliden N deposit. Emphasis is placed on characterizing the distribution and paragenetic relationships of silver-bearing minerals. The methods include core logging, sampling and mineralogical studies through light optical microscopy (LOM), scanning electron microscopy (SEM) and quantitative evaluation of mineralogy by scanning electron microscopy (QEMSCAN). Lastly, electron microprobe analysis (EMPA) was used to determine the chemical composition of silver-bearing minerals and sulphides. Mineralization types studied include 1: the main massive to semi-massive sulphide mineralization, 2: stratigraphically underlying stringer mineralization and 3: local, vein- and/or fault-hosted silver-rich mineralization in the stratigraphic hanging wall. The massive to semi-massive sulphide mineralization is dominated by sphalerite with lesser galena and pyrrhotite. In contrast, the stringer mineralization is dominated by chalcopyrite and pyrrhotite. The major minerals show evidence of a coeval formation and textural as well as structural evidence suggest that ductile deformation has affected the mineralization types. Notable evidence includes ball-ore textures, accumulation of minerals in pressure shadows and brittle fracturing of competent arsenopyrite and pyrite porphyroblasts and infilling by more incompetent sulphide minerals. The silver-bearing minerals identified are commonly spatially associated with galena and the major species is freibergite ((Ag,Cu,Fe)12(Sb,As)4S13), which also occur as inclusions in chalcopyrite mainly in the stringer mineralization. The stringer mineralization also contains notable amounts of hessite (Ag2Te). Notably, galena, pyrrhotite, freibergite and other sulphosalt minerals are commonly accumulated in pressure shadows near host rock fragments in the massive to semi-massive sulphide mineralization. The only gold-bearing mineral identified in this study is electrum (Au, Ag) in the stringer mineralization. The hanging wall mineralization locally comprises faulted and/or sheared massive sulphide mineralization which is compositionally similar to the main massive to semi-massive sulphide mineralization, besides a significantly higher content of freibergite. However, parts of the hanging wall mineralization are entirely dominated by sulphides and sulphosalts of silver, such as pyrargyrite (Ag3SbS3), pyrostilpnite (Ag3SbS3), argentopyrite (AgFe2S4), sternbergite (AgFe2S3) and stephanite (Ag5SbS4). These occur in structurally late settings, which along with consideration of their temperature stabilities suggest a late origin. Since the silver-bearing minerals in the massive to semi-massive sulphide mineralization and the two varieties of hanging wall mineralization contains the same metals, the mineralization in the hanging wall may have formed by late-stage remobilization of ore components from the underlying Rävliden N deposit. This negates the need for multiple mineralization events to explain the local silver-enriched zones in the hanging wall. The paragenetically late mineralization types contains high content of Ag-bearing minerals in relation to base metal sulphides. This suggests that remobilisation processes were important for locally upgrading the Ag-content.

Surficial geochemistry, particularly selective leach technology, has proven effective in revealing anomalous concentrations of ore indicator metals overlying zones of buried mineralization. This study focuses on the buried Zn-Cu-Au-Ag VMS deposit at McIlvenna Bay in the Flin Flon Greenstone Belt to determine whether the peat swamp at the surface contains any anomalies of ore indicator metals using simple surficial geochemical techniques. Three selective leaches were performed, ammonium acetate pH 5.0, hydroxylamine, and sodium pyrophosphate. The hydroxylamine leach, which selects for metals in the reducible phase often associated with Mn and Fe oxides, has the clearest anomaly for multiple metals observed simultaneously, at the greatest magnitude. The pyrophosphate leach, which selects for metals that are oxidizable, often associated with organics showed a clear anomaly only for Cu, despite the abundance of organic matter and its great affinity for binding metals, likely because the organic-metal complexes formed in this system are easily exchangeable and highly soluble, not allowing for the formation of clear anomalies. The use of selective leach technology on surficial soil or peat has shown to be effective for delineating ore indicator metal anomalies, giving surface projections of buried mineralization in various types of systems, as long as the dynamics of the system are well understood in order to determine the phase the metals are associated with.

This study involves the application, interpretation and utilization of regional geochemical data for target generation in the North West Province, South Africa. A regional soil geochemical survey programme has been carried out by the Council of Geoscience South Africa since 1973. A number of 1:250 000 sheet areas have been completed, but there are no interpretative maps which could aid in mineral exploration and other purposes. In order to utilize the valuable and expensive data, the project was motivated through data acquisition and interpretation to generate exploration targets. The study area is confined to Mafikeng, Vryburg, Kuruman and Christiana in the Northwest Province, where potential exploration and mining opportunities exist in areas of great geological interest. These include geological events such as the Bushveld Complex, the Kalahari manganese field and the Kraaipan greenstone belts. The aim of this project was to utilize geochemical data together with geophysical and geological information to verify and identification of possible obscured ore bodies or zones of mineralization, and to generate targets. Another objective was the author to be trained in the techniques of geochemical data processing, interpretation and integration of techniques such as geophysics, in the understanding of the geology and economic geology of the areas. Approximately 5 kg of surface soil was collected per 1 km2 by CGS from foot traversing. Pellets of the samples were prepared and analyzed for TiO2, MnO and Fe2O3, Sc, V, Cr, Ni, Co, Cu, Zn, As, Y, Ba, Nb, Rb, Th, W, Zr, Pb, Sr and U using the simultaneous wavelengthdispersive X-ray fluorescence spectrometer technique at the Council for Geoscience, South Africa. For each element the mean +2 standard deviations were used as a threshold value to separate the negative from the positive anomalies. The integration of geological, geophysical and geochemical information was used to analyze and understand the areas of interest. A number of computer programmes were extensively used for data processing, manipulation, and presentation. These include Golden Software Surfer 8®, Arc-View 3.2a®, TNT-Mips®, JMP 8 ®, and Microsoft Excel®. Through geochemical data processing and interpretation, together with the low resolution aeromagnetic data, gravity data and geological data, seven (7) exploration target areas have been generated: These have been numbered A to G. It is concluded that there is good potential for Cr, PGMs, vanadium, nickel, iron, copper, manganese, uranium and niobium in the targets generated. The results provide some indication and guide for exploration in the target areas. In Target A, Cu, Cr, Fe, Ni and V anomalies from the lower chromitite zone of far western zone of the Bushveld Complex, which has be overlain buy the thick surface sand of the Gordonia Formation. Target B occurs over the diabase, norite, andesitic lava and andalusite muscovite hornfels of the Magaliesberg Formation. This target has the potential for Cu, Fe and Ni mineralization. The felsic rocks of the Kanye Formation and the Gaborone Granite in target C have shown some positive anomalies of niobium, uranium, yttrium and rubidium which give the area potential for Nb, REE and U exploration. Target D is located on the Allanridge Formation, and has significant potential for Ni-Cu mineralization, and is associated with the komatiitic lava at the base of the Allanridge Formation in the Christiana Area. The light green tholeiitic, calc-alkali basalt and andesitic rocks of the Rietgat Formation are characterized by a north-south trending yttrium anomaly with supporting Ba and Y anomalies (Target E). This makes the area a potential target for rare earth elements. Calcrete on the west of the Kuruman has a low b potential target for vanadium. It is believed that the area might be potential for potassium-uranium vanadate minerals, carnotite which is mostly found in calcrete deposits. This study has proved to be a useful and approach in utilizing the valuable geochemical data for exploration and future mining, generated by Council for Geoscience Science. It is recommended that further detailed soil, rock and geochemical surveys and ultimately diamond drilling be carried out in the exploration target areas generated by this study.

Submitted by Stéfany Moreira (stemellra@yahoo.com.br) on 2013-02-25T12:57:59Z No. of bitstreams: 1 DISSERTAÇÃO_AproveitamentoMinériosFerro.pdf: 4941141 bytes, checksum: 7fc54169ae9d05ca62dad2964a3d2b36 (MD5)<br>Approved for entry into archive by Neide Nativa (neide@sisbin.ufop.br) on 2013-02-25T14:03:40Z (GMT) No. of bitstreams: 1 DISSERTAÇÃO_AproveitamentoMinériosFerro.pdf: 4941141 bytes, checksum: 7fc54169ae9d05ca62dad2964a3d2b36 (MD5)<br>Made available in DSpace on 2013-02-25T14:03:40Z (GMT). No. of bitstreams: 1 DISSERTAÇÃO_AproveitamentoMinériosFerro.pdf: 4941141 bytes, checksum: 7fc54169ae9d05ca62dad2964a3d2b36 (MD5) Previous issue date: 2012<br>Essa dissertação descreve a situação atual e as tendências relacionadas ao tratamento de minérios de ferro de baixo teor na indústria mineral, utilizando um estudo de caso e uma discussão sobre o projeto de implantação de uma instalação de tratamento de itabiritos de baixo teor, denominada ITM-S, a ser instalada em uma empresa mineradora de ferro no Estado de Minas Gerais. Seu objetivo principal foi analisar a viabilidade técnica e econômico-financeira desse projeto, com base nos conceitos existentes na metodologia FEL (Front-End-Loading), associados aos conceitos de sequenciamento de lavra, beneficiamento mineral e economia mineral. Foram analisados, na metodologia, dois cenários do projeto para a escolha das alternativas de rotas de processo: com o uso de separação magnética (cenário 1), e sem a utilização de separação magnética (cenário 2). Os resultados mostraram que o cenário 2 é o mais viável economicamente, devido principalmente a redução do investimento por tonelada produzida, dentre outros fatores. Pretende-se apresentar as várias evoluções nos processos de tratamento de minério de ferro, e apresentar uma metodologia adequada para análise de viabilidade de projetos de tratamento e aproveitamento de minérios de ferro marginais, como a metodologia FEL, associada aos conceitos existentes na engenharia de minas. ____________________________________________________________________________________________________<br>ABSTRACT: This dissertation describes the current situation and trends related to the exploitation of low-grade iron ore in the mineral industry, to accomplish it, a case study and a discussion on the implementation project of a treatment facility for low grade itabirites called ITM-S, to be installed in an iron ore mining company in the State of Minas Gerais, are presented. The main objective was to analyze the technical and economic-financial feasibility of this project, based on FEL methodology (Front-End- Loading) existing concepts, associated with the mining concepts of sequencing, mineral processing and mineral economics. Using this methodology, two project’s scenarios were analyzed in order to help to choose between two alternative routes: magnetic separation usage (scenario 1), and no usage of magnetic separation (scenario 2). The results showed that scenario 2 is the most economically viable; mainly due to reduction of the investment per ton produced, among other factors. This work intends to present the various evolutions in the iron ore treatment processes, and to present an appropriate methodology for marginal iron ore project feasibility analysis, such as the FEL methodology, associated with the existing concepts in mining engineering.

Thesis (MScEng)--University of Stellenbosch, 2002.<br>ENGLISH ABSTRACT: Metallurgical processes are often high dimensional and non-linear making them difficult to understand, model and control. Whereas the human eye has extensively been used in discerning temporal patterns in historical process data from these processes, the systematic study of such data has only recently come to the forefront. This resulted predominantly from the inadequacy of previously used linear techniques and the computational power required when analysing the non-linear dynamics underlying these systems. Furthermore, owing to the recent progress made with regard to the identification of non-linear systems and the increased availability of computational power, the application of non-linear modelling techniques for the development of neural network models to be used in advanced control systems has become a potential alternative to operator experience. The objective of this study was the development ofa non-linear, dynamic model of an autogenous mill for use in an advanced control system. This was accomplished through system identification, modelling and prediction, and application to control. For system identification, the attractor was reconstructed based on Taken's theorem making use of both the Method Of Delays and singular spectrum analysis. Modelling consisted of the development of multi-layer perceptron neural network, radial basis function neural network, and support vector machine models for the prediction of the power drawn by an autogenous mill. The best model was subsequently selected and validated through its application to control. This was accomplished by means of developing a neurocontroller, which was tested under simulation. Initial inspection of the process data to be modelled indicated that it contained a considerable amount noise. However, using the method of surrogate data, it was found that the time series representing the power drawn by the autogenous mill clearly exhibited deterministic character, making it suitable for predictive modelling. It was subsequently found that, when using the data for attractor reconstruction, a connection existed between the embedding strategy used, the quality of the reconstructed attractor, and the quality of the resulting model. Owing to the high degree of noise in the data it was found that the singular spectrum analysis embeddings resulted in better quality reconstructed attractors that covered a larger part of the state space when compared to the method of delays embeddings; the data embedded using singular spectrum analysis also resulting in the development of better quality models. From a modelling perspective it was found that the multi-layer perceptron neural network models generally performed the best; a multi-layer perceptron neural network model having an appropriately embedded multi-dimensional input space outperforming all the other developed models with regard to free-run prediction success. However, none of the non-linear models performed significantly better than the ARX model with regard to one-step prediction results (based on the R2 statistic); the one-step predictions having a prediction interval of 30 seconds. In general the best model was a multi-layer perceptron neural network model having an input space consisting of the FAG mill power (XI), the FAG mill load (X2), the FAG mill coarse ore feed rate (X3), the FAG mill fine ore feed rate (X4), the FAG mill inlet water flow rate (X7) and the FAG mill discharge flow rates (X9, XIO). Since the accuracy of any neural network model is highly dependent on its training data, a process model diagnostic system was developed to accompany the process model. Linear principal component analysis was used for this purposes and the resulting diagnostic system was successfully used for data validation. One of the models developed during this research was also successfully used for the development of a neurocontroller, proving its possible use in an advanced control system.<br>AFRIKAANSE OPSOMMING: Metallurgiese prosesse is gewoonlik hoogs dimensioneel en nie-lineêr, wat dit moeilik maak om te verstaan, modelleer, en te beheer. Alhoewel die menslike oog alreeds wyd gebruik word om temporale patrone in historiese proses data te onderskei, het die sistematiese studie van hierdie tipe data eers onlangs na vore gekom. Dit is hoofsaaklik na aanleiding van die onvoldoende resultate wat verkry is deur van voorafgaande lineêre tegnieke gebruik te maak, asook die beperkende berekenings vermoë wat beskikbaar was vir analise van onderliggend nie-lineêre dinamiese stelsels. 'n Verder bydraende faktor is die onlangse vordering wat gemaak is met betrekking tot die identifikasie van nie-lineêre stelsels en die toename in beskikbaarheid van rekenaar-vermoë. Die toepassing van nie-lineêre modellerings tegnieke vir die ontwikkeling van neurale netwerke om gebruik te word in gevorderde beheerstelsels, het 'n potensiële alternatief geword tot operateur ondervinding. Die doelwit van hierdie studie was die ontwikkeling van 'n gevorderde beheerstelsel vir 'n outogene meul gebaseer op 'n nie-lineêre, dinamiese model. Dit is bereik deur middel van stelsel-identifikasie, modellering en voorspelling, en laastens implementering van die beheerstelsel. Vir stelsel-identifikasie is die attraktor van die stelsel bepaal soos gebaseer op Taken se teorema deur gebruik te maak van beide die metode van vertraging en enkelvoudige spektrum analise. Modellering van die stelsel vir die voorspelling van krag-verbruik deur die outogene meul het bestaan uit die ontwikkeling van multilaag-perseptron-neurale netwerke, radiaalbasisfunksie-neurale netwerke, en steunvektor-masjien-modelle. Die beste model is daarna gekies vir validasie deur middel van toepassing vir beheer. Dit is bereik deur 'n neurobeheerder te ontwikkel en te toets deur middel van simulasie. Die aanvanklike inspeksie van proses data wat gebruik sou word vir modellering het egter getoon dat die data 'n aansienlike hoeveelheid geraas bevat. Nietemin, deur die gebruik van 'n surrogaat-data-metode, is dit bevind dat die tyd-reeks wat die krag verbruik van die outogene meul beskryf, duidelik deterministiese karakter toon en dat dit dus wenslik is om 'n nie-lineêre voorspellings-model, soos 'n neurale netwerk te gruik. Gevolglik is gevind dat, wanneer die data vir attraktor hersamestelling gebruik word, 'n verband bestaan tussen die ontvouing-strategie wat gebruik word, die kwaliteit van die gerekonstrueerde attraktor, en die kwaliteit van die daaropvolgende model. As gevolg van die geraas in die data is gevind dat die ontvouing gebaseer op enkelvoudige spektrum analise 'n beter kwaliteit attraktor hersamestelling lewer. So ook is gevind dat 'n groter deel van die toestandruimte gedek word in vergelyking met die metode van vertraging-ontvouing. Deur gebruik te maak van enkelvoudige spektrum-analise, het die dataontvouing ook beter kwaliteit modelle opgelewer. Vanuit 'n modellerings-perspektief is gevind dat die multilaag-perseptron-neurale netwerk-modelle in die algemeen die beste gevaar het. 'n Multilaag-perseptronneurale netwerk met 'n gepaste ontvoude multidimensionele invoer-spasie het die beste gevaar van al die ontwikkelde modelle met betrekking tot vryloopvoorspellings. Geen van die nie-lineêre modelle het egter beduidend (op 'n R2 basis) beter gevaar as die ARX model wanneer daar na die eenstap-voorspellings (oor 'n 30 sekonde interval) gekyk word nie. Die multilaag-perseptron-neurale netwerk met 'n invoer-spasie bestaande uit die meul krag-verbruik (XI), die meullading (X2), die meul growwe-erts voertempo (X3), die meul fyn-erts voertemp ('4), die meul inlaat-water vloeitempo (X7) en die meul uitlaat vloeitempo's (X9, XIO) het in die algemeen die beste gevaar. Aangesien die akkuraatheid van emge neurale netwerk afhanklik is van die data waarmee dit aanvanklik opgestel is, is 'n diagnostiese proses modelontwikkel om die proses-model te vergesel. Lineêre hoofkomponent analise is vir hierdie doel aangewend en die gevolglike diagnostiese stelsel is suksesvol aangewend vir datavalidasie. Een van die modelle ontwikkel gedurende hierdie navorsing is ook suksesvol gebruik vir die ontwikkeling van 'n neurobeheerder wat dien as bewys dat die model goed gebruik kan word in 'n gevorderde beheerstelsel.

O transporte de minérios através do bombeamento de polpa é relevante em escala mundial. No Brasil este modo de transporte é muito importante devido à enorme produção mineral e suas distâncias continentais. E, o bombeamento de polpa em planta é ainda mais importante pois é uma operação diária que afeta a todos os envolvidos. A motivação para este estudo foi providenciar para a Escola Politécnica uma estação de bombeamento capaz de levantar os parâmetros do escoamento necessários para o correto dimensionamento das linhas de polpa. Esta dissertação descreve a montagem de dois loops (3\'\' e 4\'\'), devidamente instrumentado e com a aquisição direta dos dados via computador. Os loops foram dimensionados, os componentes, bomba e instrumentos adquiridos, o loop montado, calibrado e colocado em marcha. Esta dissertação registra esta experiência e discute as dificuldades encontradas, na expectativa de que este sistema de bombeamento venha a ser útil para futuros pesquisadores. A Escola Politécnica agora dispõe de um loop de bombeamento de polpa mineral adequado para a determinação de parâmetros hidráulicos, pesquisa e suporte para futuros projetos.<br>Ore transportation via slurry pumping is relevant in a world scale. In Brazil, due to its huge mineral production and continental distances, mineroducts are an important transportation mode. And, in plant slurry pumping is still more important as it is a dayby- day operation that affects everybody. The motivation for this study was to provide Escola Politécnica (USP) of a convenient pumping station (loop) able to measure the necessary flow parameters for proper design of slurry lines. This dissertation describes the design of two loops (3\'\' and 4\'\') full instrumented and with direct data acquisition via computer. The loops have been sized, components, pump and instruments purchased, erected and started-up. This dissertation registers this experience and discusses the difficulties found, in the expectative can become useful for other researches. Escola Politécnica has now a proper slurry pumping loop for hydraulic determinations, research and for support of future projects.

A large portion of South west Africa/Namibia is underlain by 2 great orogens. They are the Irumide (Sinclair/Rehoboth) and Damara Orogenies. The L-shaped Irumide Province forms part of a belt which extends over the subcontinent from Namaqualand to as far as Zambia. The volcano-sedimentary sequences of the Irumide are believed to have formed in intracratonic rifts and pull-apart basins during the period 1400 to 900 Ma. The evolution of the NW trending Sinclair Group proceeded by means of 3 major cycles each beginning with the emplacement of basic to intermediate magmas followed by felsic ones. The cycle ended off with subsidence, deposition of immature clastic debris and final tilting of the volcano-clastic sequence. It was suggested that the extensive calc-alkaline lavas present, developed within a magmatic arc above a subduction zone, but this proposal has not been generally accepted. The NE trending Klein Aub-Witvlei Basins consist essentially of red bed alluvial fans and lacustrine sediments with minor volcanics near the base. The red beds and aeolian sediments were deposited in an arid climatic condition. The regional greenschist facies metamorphism and deformation is attributed to a major tectono-thermal event at 1100 Ma. The Damara Orogen (900 - 550 Ma) forms part of the Pan-African mobile belt system of global proportions. The NE trending intracontinental branch (aulacogen) and 2 coastal branches constitute a triple junction with its focal point near Swakopmund. The NE extension of the intracontinental belt has been linked with the Lufilian Arc hosting the renown Zambian Copper Belt deposits. In South West Africa/Namibia this belt hosts many different mineral occurrences which can be grouped into rift and collision related deposits. The tectonic history of the Damara Orogen supports a geodynamic-evolution-with-time hypothesis and represents a transitional phase in which limited Wilson Cycle Tectonics was active. The Theory of Mantle Advection is invoked to explain rifting, thinning and subsidence. Extensive ensialic rifting resulted in a relatively stable Northern Carbonate Platform and several deep troughs hosting turbiditic sequences. Crustal rupture in the Khomas Trough allowed for the emplacement of ocean floor tholeiites known as the Matchless Amphibolite Belt. Subsequent ocean closure and collision resulted in deformation, metamorphism and generation of predominantly S-type granites. The southern continental plate was partially overridden by the northern plate during final collision at 550 Ma. These low angle thrust faults allowed for the emplacement of the Naukluft Nappe Complex on top of younger Nama sediments. The break up of Gondwanaland during the Mesozoic with the splitting of the Atlantic Ocean was responsible for the intrusion of anorogenic alkaline ring complexes along the extension of the NE trending transform faults within the intracontinental branch of the Damara Orogen. A close relationship between the tectonic setting and mineral deposits has been recognized in both the Irumide and Damara Orogenies. In the Irumide, stratiform syngenetic copper deposits are hosted by alluvial fan, playa and lacustrine sediments. The uninterrupted sedimentation from the Irumide to Damara Orogen resulted in similar stratiform copper deposits during the early stages of rifting. In the Damara Orogen the rifting (extensional) phase is characterized by 4 main mineralizing systems: diagenetic/syngenetic (Kupferschiefer-type), epigenetic/hydrothermal Cu-Pb-Zn (Mississippi Valley-type), volcanogenic cupriferous pyrite (Besshi-type) and volcano-exhalative Pb-Zn (Red Sea-type). The collision (compressional) phase was accompanied by 4 main mineralizing processes: epigenetic/hydrothermal Cu-Pb-Zn, hydrotheral/metasomatic Sn-W-rare earth, metamorphogenic Au and U-bearing anatectic melts. The key to the selection of viable exploration targets lies in the understanding of the field evidence and the geodynamics modelling to explain the evolution of the orogen and its associated mineral deposits.

Le minerai de fer est la principale matière première utilisée dans la production d’acier etdoit en général être traité de manière à répondre aux spécifications requises par l’industrie de l’acier. L’industrie du minerai de fer fait désormais face à des gisements de plus en plus pauvres avec des assemblages de minéraux complexes. L’objective de cette étude est de valoriser un concentré magnétique de la mine de Peña Colorada (Mexique) via flottation cationique inverse. La mine de Peña Colorada est un gisement de type skarn ayant une teneur moyenne en fer de 36%. Il est composé de plusieurs phases minérales identifiées dans un programme détaillé de caractérisation minéralogique. Les silicates de fer tels que la chamosite et l’épidote sont les minéraux les plus problématiques car ils présentent certaines propriétés proches des oxydes de fer. Le traitement actuel de ce minerai se fait par séparation magnétique et pourtant la teneur en silice du concentré final reste comprise entre 4 et 5%, ce qui est trop élevé pour le traitement en amont. Les techniques traditionnelles telles que la séparation magnétique ou la séparation par gravité ne peuvent pas entrainer une séparation plus poussée. Les propriétés physiques de ces minéraux associés à la libération fine, atteinte seulement au niveau du micromètres, n’ont pas assez de contraste pour que cette séparation aye lieu. La flottation est proposée dans cette étude comme une technique capable de jouer plus finement avec ces propriétés pour rendre cette séparation possible. L’étude de la chimie de surface des minéraux, associée à des isothermes comparatifs d’adsorption avec des déprimants, a montré que l’amidon de maïs ne favorise pas la sélectivité pour un minerai de fer aussi complexe, puisqu’il s’adsorbe sur tous les minéraux. L’essai de déprimants alternatifs a montré que l’acide humique était un déprimant viable permettant de garantir le niveau de sélectivité requis dans la séparation par flottation. Des expériences de micro-flottation avec des minéraux purs montrent que la chamosite se comporte de manière très similaire aux oxydes de fer, ne présentant pas de bonnes capacités de flottabilité avec les amines, comme les deux autres silicates. Les tests de flottation à l’échelle du laboratoire avec un matériau préalablement tamisé à 53 μm conduisent à un concentré de haute qualité avec 1,82% de silice et 84% de récupération de fer, lorsque l’acide humique est sélectionné comme déprimant. Des essais en circuit fermé (locked cycle test) tentant de simuler un processus continu ont donné une excellente réponse d’un concentré contenant 2,78% de silice et 85% de récupération de fer, avec un polysaccharide naturel modifié comme déprimant. Des essais pilotes ont également confirmé la faisabilité de la méthode avec un concentré contenant 2,06% de silice et 64% de récupération de fer, ce qui devrait être amélioré en ajoutant davantage d’étapes d’épuisage. L’utilisation de la flottation en colonne pour cette étape est tout à fait possible, étant donné que ses tests ont indiqué une récupération de fer élevée de 96%. Une voie de concentration combinant un tamisage fin à 53 μm ainsi qu’une flottation cationique inverse des silicates en utilisant un déprimant alternatif comme l’acide humique ou des polysaccharides naturels modifiés s’est révélée efficace pour atteindre les niveaux de qualité souhaités pour le concentré de fer à des taux de récupération élevés. Enfin, la modélisation moléculaire a révélé que le comportement particulier de la chamosite est principalement dû au fait qu’elle est moins hydrophile que les autres minéraux impliqués dans la flottation<br>Iron ore is the main raw material for the steel production and generally it must be processed to reach the specifications required by the steel industry. The iron ore mining industry is nowfacing increasingly lean-grade deposits with complex mineral assemblages. This study addresses the upgrade of a magnetic concentrate from Peña Colorada mine in Mexico by reverse cationic flotation. Peña Colorada deposit is an iron skarn with an average iron content of 36%. It is composed by several mineral phases that were identified in a detailed mineralogical characterisation programme. Iron-bearing silicates such as chamosite and epidote are the problematic minerals to draw attention to. They present certain properties that are like the iron oxides. The current processing of this ore is made by magnetic separation and yet the silica content of the final concentrate remains between 4 and 5%, too high for the upstream process. Traditional techniques like magnetic separation or gravity separation are not capable to promote further separation. The intrinsic properties of these minerals do not have enough contrast and the liberation is reached only at micrometre sizes. Flotation is proposed in this study as a technique capable of playing with those properties to make this separation possible. The surface chemistry study of the minerals coupled with comparative adsorption isotherms with depressants, has shown that corn starch does not promote selectivity for such a complex iron ore, adsorbing on all minerals. The testing of alternative depressants highlighted humic acid as a viable depressant to sponsor the required level of selectivity in the separation by flotation. Micro-flotation experiments with pure minerals show that chamosite behaves very similar to iron oxides, not presenting good floatabilities with amines, like the other two silicates. Bench flotation tests with a material previously screened at 53 μm leads to a high-quality concentrate with 1.82% of silica and 84% of iron recovery, when humic acid is selected as depressant. Locked cycle tests trying to simulate a continuous process gave an excellent response of a concentrate with 2.78% of silica and 85% of iron recovery, with an altered natural polysaccharide as depressant. Pilot tests also confirmed the feasibility of the method with a concentrate with 2.06% of silica content and 64% of iron recovery, that should be improved by the addition of more scavenger stages. The use of column flotation for this stage is entirely possible, considering that its tests indicated a high iron recovery of 96%. A concentration route combining fine screening at 53 μm and reverse cationic flotation of silicates using alternative depressant as humic acid or altered natural polysaccharides has proven to be effective in achieving the desired quality levels for the iron concentrate at high iron recovery levels. Finally, molecular modelling identified that the strange behaviour of chamosite is mainly because it is less hydrophilic than the other minerals involved in flotation

O trabalho proposto considerou o desenvolvimento de uma abordagem por autômatos celulares para modelagem de recursos minerais. De uma maneira geral, os autômatos celulares permitem a modelagem de sistemas e fenômenos levando em conta parâmetros de forma, dimensão, geometria, regras de evolução, regras de vizinhança e estado inicial. Para a aplicação dos autômatos celulares, foi desenvolvida uma ferramenta de software com apoio do Núcleo de Desenvolvimento de Software, do Departamento de Engenharia de Departamento de Sistemas Eletrônicos da Escola Politécnica da Universidade de São Paulo. A ferramenta de modelagem desenvolvida foi aplicada para modelar um banco de dados conhecido na mineração, que é o Walker Lake Dataset Isaaks e Srivastava (1989). Os resultados obtidos demonstraram que a abordagem por ACs tem potencial para a área de modelagem de recursos minerais, e indicaram a importância de definir uma metodologia específica para a seleção do método de interpolação mais adequado para cada conjunto de dados estudados.<br>This research project proposes a new approach for modeling geological resources using cellular automata. In general, cellular automata allow modeling systems taking into account parameters of shape, dimensions, evolution rules, neighboring rules and initial state of the cells. For the application of cellular automata in this project, a new tool has been developed in conjunction with the Software Development Group of the Department of Electronics of University of São Paulo. The modeling tool has been applied to model a popular dataset in mining which is the Waker Lake dataset (Isaaks e Srivastava,1989). The results showed that the approach has potential for ACs to the area of modeling of mineral resources and indicated the importance of defining an interpolation method most appropriate for evolutionary change of ACs for the dataset studied.

Lead isotope compositions have been obtained from five major volcanic and intrusive rock suites and several ore deposits on Vancouver Island. Lead, uranium and thorium concentrations and strontium isotope ratios have been obtained for a subset of these samples. The rock suites examined are the Paleozoic Sicker Group, Triassic Karmutsen Formation, Jurassic Island Intrusions and Bonanza Group volcanic rocks, and the Eocene Catface intrusions. Isotope geochemistry of the Sicker Group is consistent with the interpretation that it formed as an island arc. Relatively high 207pb/204pb ratios indicate sediment involvement in the subduction process, which suggests that the Sicker Group formed close to a continent. Buttle Lake ore deposits display decreasingly radiogenic lead isotope ratios with time, suggesting that the associated magmas become increasingly primitive. This supports the hypothesis that these deposits formed during the establishment of rifting in a back-arc environment. Karmutsen Formation flood basalts display isotopic mixing between an ocean island-type mantle source and average crust. Isotopic evidence is used to support a Northern Hemisphere origin for these basalts. Mixing is apparent in the lead and strontium isotope signatures of the Island Intrusions and Bonanza Group volcanic rocks, between depleted mantle and crustal (possibly trench sediments) components. This is consistent with formation of these rocks in an island arc environment. Eocene Catface intrusions have relatively high 207pb/204pb indicating that crustal material was involved in their formation. There are two groups of plutons corresponding to an east belt and west belt classification. Galena from the Zeballos mining camp related to the Eocene Zeballos pluton indicates that the mineralization was derived from the pluton. Galena lead isotope data from Vancouver Island may be interpreted in a general way by comparison with data from deposits elsewhere of known age and origin. No single growth curve model can be applied. Lead isotope characteristics of Vancouver Island are clearly different from those of the North American craton, reflecting the oceanic affinities of this terrane. A new technique has been developed to compare 207pb/204pb ratios between samples with differing 206pb/204pb ratios. The procedure projects 207pb/204pb ratios along suitable isochrons until they intersect a reference value of 206pb/204pb. This technique can be used for interpreting lead isotope data from old terranes, in which lead and uranium may have undergone loss or gain, and if lead and uranium abundances have not been measured.<br>Science, Faculty of<br>Earth, Ocean and Atmospheric Sciences, Department of<br>Graduate

Fluids play a vital role in essentially all geologic environments and processes, and are the principal media of heat and mass transfer in the Earth. The properties of geologic fluids can be diverse, as fluids occur at conditions ranging from ambient temperatures and pressures at Earth's surface, to extreme temperatures and pressures in Earth's deep interior. Regardless the wide ranges of conditions at which geologic fluids occur, fluid properties are described and governed by the same fundamental thermodynamic relationships. Thus, application of thermodynamic principles and methods allows us to decipher the properties and roles of geologic fluids, to help understand geologic processes. Fluid inclusions in minerals provide one of the best available tools to study the compositions of geological fluids. Compositions of fluid inclusions can be determined from microthermometric measurements, based on the vapor-saturated liquidus conditions of model chemical systems, or by various microanalytical techniques. The vaporsaturated liquidus relations of the system H2O-NaCl-CaCl2 have been modeled to allow estimation of fluid inclusion compositions by either microthermometric or microanalytical methods. Carbon capture and storage (CCS) in deep saline formations represents one option for reducing anthropogenic CO2 emissions into Earth's atmosphere. Availability of storage volume in deep saline formations is a significant component of injection and storage planning. Investigation of the volumetric properties of CO2, brine and CO2-saturated brine reveals that storage volume requirements are minimized when CO2 dissolves into brine. These results suggest that a protocol involving brine extraction, CO2 dissolution and re-injection may optimize CCS in deep saline formations. Numerical modeling of quartz dissolution and precipitation in a sub-seafloor hydrothermal system was used to understand the role of fluid-phase immiscibility ("boiling") on quartz-fluid interactions, and to predict where in the system quartz could deposit and trap fluid inclusions. The spatial distribution of zones of quartz dissolution and precipitation is complex, owing to the many inter-related factors controlling quartz solubility. Immiscibility exerts a strong control over the occurrence of quartz precipitation in the deeper regions of fluid circulation.<br>Ph. D.

Des études géochimiques et morphoscopiques de l'or natif dans différents types de minéralisations aurifères, intégrées dans chaque cas au contexte gitologique, ont permis de déterminer les mécanismes de mise en place de l'or. Dans les veines de quartz aurifères des ceintures de roches vertes des mines de fazenda brasileiro et maria Lazara (brésil), il existe deux générations d'or natif, systématiquement associées à des sulfures, en présence de microfractures. La présence de grains d'or à aspect globulaire-réniforme et à développement bidimensionnel avec de nombreuses perimorphoses rhombiques, prouvent que les surfaces des arsénopyrites riches en s jouent un rôle fondamental dans la fixation et la précipitation de l'or. Ces arsénopyrites sont des semi-conducteurs de type n sur lesquels au#l serait adsorbé après destruction des complexes anioniques aureux dans les fluides puis réduit. On retrouve des grains d'or à développement bidimensionnel moulant des tourmalines à partir de microfractures dans le cas d'une veine en extension de la mine sigma (Canada). La réduction de l'or serait alors liée à la présence de fe#2#+. Dans les veines aurifères des formations sédimentaires protérozoïque moyen à supérieur de la mine de santa Rita (brésil), l'or est intégré dans des pyrites a bandes de croissance riches en as soit en position interstitielle ou sur des sites de substitution dans le réseau des pyrites, soit sous forme de crypto-inclusions d'une phase riche en or. Dans le profil latéritique de Garimpos Da Cangas (brésil), post-pléistocène inferieur, les études de l'or du niveau exploité dans la partie supérieure de la mottle zone et a la base de la cuirasse révèlent la présence de grains d'or visibles et l'absence d'or fin de taille micronique. Les grains ont un aspect frais ou sont légèrement arrondis avec des teneurs en ag reparties de façon homogène. D'autres grains à aspect d'éponge, résiduels, caractérisent la présence d'une paragenèse primaire a sulfures de bi et te. Toutes les données obtenues sur le profil, montrent que l'horizon exploité est issu de phases d'altération antérieures au développement du profil latéritique sur la pénéplaine. L'or n'y est pas actuellement remobilisé