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1
Cheng, Jun Hua, Jian Zhang e Di Jiang Wen. "Comparison of Leaching Characteristics of Lead in Waste CRTs". Advanced Materials Research 177 (dicembre 2010): 470–74. http://dx.doi.org/10.4028/www.scientific.net/amr.177.470.
Testo completoAbstract (sommario):
This study investigates four extraction methods (water extraction, toxicity characteristics leaching procedure (TCLP), modified TCLP with pH control and sequential chemical extraction (SCE)), each representing different liquid-to-solid (L/S) ratios, pH controls, and types of leachant and their effects on the leaching concentration of Pb in cathode ray tubes (CRTs).The results indicated that for extraction with distilled water,the lead leaching concentration (mg/L) decreased with L/S ratio in the range of 2-100. The results also showed that the leaching concentration was strongly pH-dependent in the TCLP and modified TCLP tests. In modified TCLP tests,in the case of pHs lower than 6.3,the leaching concentrations of Pb decreased with an increase in pH. Due to the nature of amphoteric elements, in the case of pHs higher than 7, the Pb leaching concentration increased with increasing pH. In SCE tests, the Pb speciation approached the extractable carbonate bound fraction. Both amounts of Pb leached from the SCE and modified TCLP tests were much higher than those for the regular TCLP and water extraction tests. The initial particle size of samples have great effect on the leachability of Pb from waste CRTs.
2
Ugurlu, Aysenur. "Leaching characteristics of fly ash". Environmental Geology 46, n. 6-7 (9 giugno 2004): 890–95. http://dx.doi.org/10.1007/s00254-004-1100-6.
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3
Fang, Hui, Xin Wu, Cai Liang e Yongshi Feng. "Study on leaching characteristics of MSWIFA in different pH environment". Advances in Engineering Technology Research 1, n. 2 (23 settembre 2022): 110. http://dx.doi.org/10.56028/aetr.1.2.110.
Testo completoAbstract (sommario):
The change of leaching solution of waste incineration fly ash (MSWIFA) after shaking under different initial extractant pH was studied, and the change trend was compared with that of fly ash under different extractant concentrations. In addition, the leaching characteristics of heavy metals were analyzed under the two methods. The results showed that the pH change of the initial extractant can not truly simulate the environment of fly ash landfill, and the former can not reflect the pH of the final leaching solution. Changing the initial extractant concentration within a certain range can gradually change the final leaching solution from alkaline to acidic, which can truly reflect the environmental changes experienced by fly ash in the landfill (such as rainstorm scouring, drought and other environment). The leaching concentration of heavy metals in the leaching solution obtained by shaking fly ash under different acetic acid concentrations reflects the actual leaching characteristics of heavy metals under different pH conditions, in which Pb and Zn are amphoteric leaching, and the other metals are cationic leaching.
4
Fang, Hui, Xin Wu, Cai Liang e Yongshi Feng. "Study on leaching characteristics of MSWIFA in different pH environment". Advances in Engineering Technology Research 2, n. 1 (23 settembre 2022): 110. http://dx.doi.org/10.56028/aetr.2.1.110.
Testo completoAbstract (sommario):
The change of leaching solution of waste incineration fly ash (MSWIFA) after shaking under different initial extractant pH was studied, and the change trend was compared with that of fly ash under different extractant concentrations. In addition, the leaching characteristics of heavy metals were analyzed under the two methods. The results showed that the pH change of the initial extractant can not truly simulate the environment of fly ash landfill, and the former can not reflect the pH of the final leaching solution. Changing the initial extractant concentration within a certain range can gradually change the final leaching solution from alkaline to acidic, which can truly reflect the environmental changes experienced by fly ash in the landfill (such as rainstorm scouring, drought and other environment). The leaching concentration of heavy metals in the leaching solution obtained by shaking fly ash under different acetic acid concentrations reflects the actual leaching characteristics of heavy metals under different pH conditions, in which Pb and Zn are amphoteric leaching, and the other metals are cationic leaching.
5
Li, Xiang, Liang Zhang e Jia Zheng Li. "Leaching Characteristics of Cement-Fly Ash Pastes". Advanced Materials Research 557-559 (luglio 2012): 915–19. http://dx.doi.org/10.4028/www.scientific.net/amr.557-559.915.
Testo completoAbstract (sommario):
The leaching characteristics of cement-fly ash pastes were investigated by MIP, XRD and TG. The results show that the microstructure of hardened cement-fly ash paste deteriorates partly after leaching of soft water. At the leaching duration of 180 days, the hardened paste containing fly ash deteriorated a little more serious than the plain cement paste, but the incorporation of fly ash in a proper ratio was helpful to defer the trend of deterioration of the hardened paste microstructure. The microstructural stability of hardened cement-fly ash paste wasn’t damaged severely during the 180 days leaching duration.
6
Cui, Yulong, Jiannan Chen, Yibo Zhang, Daoping Peng, Tao Huang e Chunwei Sun. "pH-Dependent Leaching Characteristics of Major and Toxic Elements from Red Mud". International Journal of Environmental Research and Public Health 16, n. 11 (10 giugno 2019): 2046. http://dx.doi.org/10.3390/ijerph16112046.
Testo completoAbstract (sommario):
This study analyzes the leaching behavior of elements from red mud (bauxite residue) at pH values ranging from 2 to 13. The leaching characteristics of metals and contaminated anions in five red mud samples produced by Bayer and combined processes were analyzed using the batch leaching technique following the US Environmental Protection Agency (USEPA) Method 1313. In addition, the geochemical model of MINTEQ 3.1 was used to identify the leaching mechanisms of metals. The results showed that Ca, Mg, and Ba follow the cationic leaching pattern. Al, As, and Cr show an amphoteric leaching pattern. The leaching of Cl− is unaffected by the pH. The maximum leaching concentration of the proprietary elements occurs under extremely acidic conditions (pH = 2), except for As. The leaching concentration of F− reaches 1.4–27.0 mg/L in natural pH conditions (i.e., no acid or base addition). At the same pH level, the leaching concentrations of Pb, As, Cr, and Cu are generally higher from red mud produced by the combined process than that those of red mud from the Bayer process. The leaching concentration of these elements is not strongly related to the total elemental concentration in the red mud. Geochemical modeling analysis indicates that the leaching of metal elements, including Al, Ca, Fe, Cr, Cu, Pb, Mg, Ba, and Mn, in red mud are controlled by solubility. The leaching of these elements depended on the dissolution/precipitation of their (hydr)oxides, carbonate, or sulfate solids.
7
Lun, Dian, Taiping Yuan, Xiaolong Yang, Hongliu Rong, Junjie Shi e Minqiang Pan. "Effect of Fly Ash on Leaching Characteristics of Cement-Stabilized Macadam Base". Materials 14, n. 20 (9 ottobre 2021): 5935. http://dx.doi.org/10.3390/ma14205935.
Testo completoAbstract (sommario):
To study the leaching characteristics of a cement-stabilized macadam base with fly ash, a calcium leaching test, using varying cement and fly ash dosages in an ammonium chloride solution, was designed to obtain the rate of calcium ion leaching, porosity, and permeability coefficient of cement-stabilized macadam with leaching time. The results showed that the number of leached calcium ions increased with the cement dosage in the leaching of cement-stabilized macadam. With an increase in the cement dosage, the leaching rate of calcium ions decreased, and the leaching process of the material was delayed. The incorporation of fly ash could effectively slow down the degree of calcium ion leaching. The permeability coefficient increased gradually with the extension of leaching time, and the increase in fly ash content had a more significant effect on the improvement of the permeability coefficient than the increase in cement dosage did.
8
Snow, V. O., e T. A. White. "Process-based modelling to understand which ryegrass characteristics can increase production and decrease leaching in grazed grass–legume pastures". Crop and Pasture Science 64, n. 3 (2013): 265. http://dx.doi.org/10.1071/cp13074.
Testo completoAbstract (sommario):
A significant challenge for the pastoral farming systems is to maintain or increase production while reducing leaching of nitrogen, and for pastoral systems, this means reducing leaching from urine patches. Here we explore the potential impact of four ryegrass characteristics to increase pasture production and reduce leaching from ryegrass–white clover pastures. We focus on understanding which characteristics are desirable, the stage before investigating the achievability of those characteristics in a breeding program. Those characteristics were: the winter- or summer-dominance of growth (GP); the ability of the plant to intercept radiation at low pasture mass (LI); rooting depth (RD); and resistance to moderate water stress (WF). The impact of these ryegrass characteristics, both singly and combined within a ryegrass–clover pasture, was explored across a range of soils, climates, irrigation management, and urine patch concentrations using the process-based model APSIM. Of the four characteristics tested, LI was the most effective in increasing production and reducing leaching in all environments. The characteristics RD and WF were moderately effective, with RD having a greater impact on reducing leaching whereas WF had a greater effect on increasing production. The characteristic with the least impact was GP and it seems that ryegrass is currently well adapted for typical temperatures in New Zealand. The production and environmental effects of the characteristics were additive. The characteristics should be investigated further in the typically more diverse mixtures normally found in pastures but show promise for achieving improved production while reducing leaching provided they can be achieved in a breeding program.
9
Fibrianty, Fibrianty, Eko Hanudin e Azwar Ma’as. "Leaching Characteristics of Udipsamment Ameliored by Mineral Soil and Adhesive Polymer". JOURNAL OF TROPICAL SOILS 27, n. 1 (17 gennaio 2022): 17. http://dx.doi.org/10.5400/jts.2022.v27i1.17-25.
Testo completoAbstract (sommario):
Udipsamment is characterized by sand fraction > 95%, loose, and very high leaching. This study aimed to determine the effect of mineral soil ameliorants and adhesive polymers on the character of nutrient leaching in Udipsamment. The leaching study in lysimeters used a completely randomized design with three replications. The treatments consist of bagasse (B), mineral soil included Inceptisol (I) and Vertisol (V), and adhesive polymers included tapioca 1% and 2% (T1 and T2), tapioca dregs 1% and 2 % (A1 and A2), Polyvinylalcohol 0.1% and 0.2% (P1 and P2). Combination of treatments are IB, VB, IBT1, IBT2, VBT1, VBT2, IBA1, IBA2, VBA1 , VBA2 , IBP1, I BP2, VBP1, and VBP2. Observations were made before and after leaching. The research showed that VBT2 increases moisture-holding capacity. Amelioration improved the ability of Udipsamment to hold nutrients, after leaching for six months, there was a decrease in organic C, total N, and available P compared to before leaching. Amelioration increased the soil CEC, even up to the sixth month leaching, the soil CEC showed a higher value than before leaching. The amount of clay fraction was relatively uniform between the surface and the bottom of the lysimeter, indicating that the adhesive polymer successfully bonding the clay-sand particles and prevented clay leaching.
10
Ji, Shu Hua, e Jiang Yang Deng. "Numerical Simulation on Characteristics of Nitrate Nitrogen Leaching under Different Irrigation Levels". Applied Mechanics and Materials 662 (ottobre 2014): 153–59. http://dx.doi.org/10.4028/www.scientific.net/amm.662.153.
Testo completoAbstract (sommario):
The characteristics of nitrate nitrogen leaching in soil under different irrigation levels were studied by soil column simulation experiment with numerical simulation done using LEACHM model taking nitrate nitrogen leaching under different irrigation levels as the research background. In sandy soils, an irrigation amount of 300 mm would cause nitrate nitrogen to leach downward 75~150 cm, with a leaching amount of 10~30.7 kg/ha; and an irrigation amount of 700 mm would make nitrate nitrogen leach downward about 3.5 m, with a leaching amount of 98 kg/ha. Research data showed that the amount of nitrate nitrogen leaching was positively correlated with the irrigation intensity level, irrigation level directly determined the amount of nitrate nitrogen leaching, and influenced its leaching depth.
11
Wang, Yuan, Mengmeng Tao, Di Feng, Yu Jiao, Yulong Niu e Zhikui Wang. "Effect of Leaching Behavior on the Geometric and Hydraulic Characteristics of Concrete Fracture". Materials 15, n. 13 (29 giugno 2022): 4584. http://dx.doi.org/10.3390/ma15134584.
Testo completoAbstract (sommario):
The leaching of material from concrete fracture surfaces has an impact on the structural concrete in service, but the number of studies that consider the effect of the coupling of the leaching, fracture geometry and hydraulic processes on concrete fractures is insufficient. In this study, a series of experiments was conducted, and a leaching model proposed, to investigate the mechanism of leaching behavior on the geometric and hydraulic characteristics of concrete fractures. Following the leaching experiment, the evolution of fracture geometric characteristics was observed by a three-dimensional (3D) laser scanning technique, finding that the fracture produces residual leached depth and local uneven leaching, which results in a decrease in roughness. The hydraulic characteristics were then investigated by permeability tests, and it was found that the fracture hydraulic aperture and permeability increase monotonically with leaching time. A simulation of fluid flow in a numerical fracture revealed the effect of residual leached depth and a decrease in roughness on the hydraulic characteristics. Finally, based on the analysis of the chemical composition of the leaching solution, a leaching model of concrete rough fracture surface is proposed and the mechanism of leaching behavior is discussed. These new findings are useful for the understanding of the development of leaching, local to concrete fracture surfaces.
12
PENG, Bing-xian, e Dai-she WU. "Leaching characteristics of bromine in coal". Journal of Fuel Chemistry and Technology 39, n. 9 (settembre 2011): 647–51. http://dx.doi.org/10.1016/s1872-5813(11)60040-6.
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Edwards, Matthew K., Sandra K. Fiskum, Rick W. Shimskey e Reid A. Peterson. "Leaching Characteristics of Hanford Ferrocyanide Wastes". Industrial & Engineering Chemistry Research 49, n. 4 (17 febbraio 2010): 1792–98. http://dx.doi.org/10.1021/ie901034m.
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Tong, Linlin, Qianfei Zhao, Qiang Liu, Zhehao Li, Chongzhe Chi, Yu Zhang e Hongying Yang. "Cyanide Release Characteristics of Solid Waste in Gold Smelting Process". Minerals 12, n. 10 (8 ottobre 2022): 1269. http://dx.doi.org/10.3390/min12101269.
Testo completoAbstract (sommario):
To explore the relationship between total cyanide and easily liberatable cyanide in cyanide tailings and its impact on the environment, the leaching and release characteristics of total cyanide and easily liberatable cyanide in a tailings pond were studied using a dynamic leaching experiment, and a dynamic model was established. The results show that the release concentration of total cyanide in cyanide tailings is higher than that of easily liberatable cyanide. With the increase in leaching time, the release of cyanide is more sensitive to leaching intensity. The first-order kinetic, second-order kinetic, modified Elovich, double constant, and parabolic diffusion equations were used to fit the cumulative release of cyanide. According to the kinetic results of cyanide cumulative release, in addition to the first-order kinetic equation, the other four equations revealed good fitting for the cyanide leaching process, which shows that cyanide released under simulated rainwater leaching was not simply via surface diffusion, but controlled by multiple factors.
15
Xu, Zheng, Tao Yang, Li Mei Yang e Yi Han Na Hu. "Characteristics of Bioleaching Copper Remainders of Waste Printed Circuit Boards". Advanced Materials Research 955-959 (giugno 2014): 2649–52. http://dx.doi.org/10.4028/www.scientific.net/amr.955-959.2649.
Testo completoAbstract (sommario):
Printed circuit boards are part of computer and their compositions are quite varied, containing polymers, ceramics and metals. Bioleaching copper from the printed circuit boards (PCB) by Acidithiobacillus ferrooxidans (A. f.) had been proved to be feasible in our recent work. The characteristics of the remainders of copper were carefully observed by field emission scanning electron microscope (FESEM). It is found that the leaching pits were common on the surface of the leached copper and some crystal substances were also found on the surface. The EDS analysis was used to determine the elements of different area. The leaching pits area was consisted of copper and the crystal area was consisted of copper and oxygen. The surface shape of bioleached copper was compared with acid leaching copper and Fe3+ leaching copper. Different leaching method can get different morphology due to the different leaching mechanisms. The results can help us to understand the mechanism of the copper bioleaching by microorganism.
16
Zha, Fusheng, Congmin Liu, Bo Kang, Long Xu, Chengbin Yang, Chengfu Chu, Chuang Yu, Wei Zhang, Jiwen Zhang e Zhenghong Liu. "Effect of Carbonation on the Leachability of Solidified/Stabilized Lead-Contaminated Expansive Soil". Advances in Civil Engineering 2021 (11 febbraio 2021): 1–13. http://dx.doi.org/10.1155/2021/8880818.
Testo completoAbstract (sommario):
Lime, fly ash, and alkaline residue are used widely as effective binders to solidify/stabilize heavy metal-contaminated expansive soil. Carbonation, however, may influence the effectiveness of solidification/stabilization (S/S) by decomposing hydration products and decreasing pH, which would seriously damage the long-term durability of stabilized soils. This study focused on the variation of leaching characteristics of solidified/stabilized lead-contaminated expansive soils before and after accelerated carbonation under the leachant of pH 3 and 5 by the semidynamic leaching test. After semidynamic leaching, leaching indexes such as the effective diffusion coefficient (De), leachability index (Lx), and slope (rc) were used to reveal the ion leaching mechanism. The results indicated that the amount of Pb2+ and Ca2+ leached out under different pH conditions increased after carbonation, which confirmed that carbonate on solidified/stabilized lead (Pb) had a negative impact. Additionally, the De values of Pb2+ and Ca2+ varied in the range of 1.16E − 10 cm2/s to 1.71E − 07 cm2/s, which demonstrated that ion migration was low. The contaminated soil solidified by lime and AR could be used in “controlled utilization” as Lx was higher than 9, and the leaching process was controlled by a dissolution reaction according to the analysis of rc. Moreover, the strong acidic leachant (pH = 3) resulted in more ions leaching out and lower pH in leachate compared with a mildly acidic leachant. Finally, with literature and experimental results, we found that the main reason for the increase of lead ion filtration of the carbonation reduced the pH value of the matrix and made the hydration products denatured and decomposed.
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Zhang, Lunchao, Jikai Zhou, Xu He e Chen Chen. "XRD-Rietveld Method for Evaluating the Leaching Characteristics of Hardened Cement Paste in Flowing Water". Advances in Civil Engineering 2020 (18 agosto 2020): 1–12. http://dx.doi.org/10.1155/2020/6715271.
Testo completoAbstract (sommario):
In order to study the leaching characteristics of hardened cement paste by flowing environmental water, indoor simulated leaching tests of Portland cement paste were carried out at different flow velocities with home-made flow field device and tap water as the erosion medium. By means of mechanical properties tests, X-ray diffraction (XRD), and Rietveld full-spectrum quantitative analysis of specimens after leaching at different ages, the change rules of the flexural strength, main phase composition, and mass fraction of the specimens after leaching were obtained. The results show that, within 90 days, the flow rate in the test has no obvious effect on the leaching of hardened cement paste. With the increase in age, the leaching of hardened cement paste gets more obvious. Rietveld full-spectrum quantitative analysis shows that the leaching of hardened cement paste changes with the relative content of CaCO3 and Ca(OH)2. The higher the relative content of CaCO3 is, the better compaction and leaching resistance the paste has. The leaching resistance of hardened cement paste is also related to the gradient of Ca(OH)2. The smaller the gradient is, the better the leaching resistance is. The Rietveld full-spectrum quantitative analysis method can be used as a method to evaluate the leaching effect of hardened cement paste.
18
Guo, Zhong-qun, Ling-feng Liu, Tao Tang, Ke-fan Zhou e Xiao-jun Wang. "Influence of Leaching Solution on the Soil-Water Characteristics of Ion-Absorbed Rare Earth Minerals and Its Hysteresis Effect". Minerals 13, n. 5 (3 maggio 2023): 637. http://dx.doi.org/10.3390/min13050637.
Testo completoAbstract (sommario):
Thesoil-water characteristic curve is the basic constitutive relation to express the water-holding characteristics of ion-absorbed rare earth. The simulated solution mining test and pressure plate apparatus tests were carried out, the relationship between matric suction and water content under different leaching actions was obtained. Using the Fredlund and Xing four-parameter model, the soil-water characteristic curves of ion-absorbed rare earth under different leaching actionswereobtained, and the changing trend of each parameterwas analyzed, and the influence of different leaching methods on the water-holding characteristic of soil was obtained.For different types of leaching solutions, the water-holding capacity of the soil varies from strong to weak forpure water, the 3% magnesium sulfate solution, and the 3% ammonium sulfate solution; as the concentration of the leaching solution increases, the water-holding capacity of the sample gradually decreases, and it decreases most significantly from 0% to 2%. Moreover, the saliency of the “hysteresis effect” of the soil-water characteristic curve was from high to low forpure water, the 3% magnesium sulfate solution, and the 3% ammonium sulfate solution, and the “hysteresis effect” showed a decreasing trendwith the increasein the concentration.
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Hwang, Soonho, Younggu Her, Sang Min Jun, Jung-Hun Song, Goontaek Lee e Moonseong Kang. "Characteristics of Arsenic Leached from Sediments: Agricultural Implications of Abandoned Mines". Applied Sciences 9, n. 21 (31 ottobre 2019): 4628. http://dx.doi.org/10.3390/app9214628.
Testo completoAbstract (sommario):
Heavy metals, including arsenic from abandoned mines, are easily transported with sediment and deposited in waterbodies such as reservoirs and lakes, creating critical water quality issues when they are released. Understanding the leaching of heavy metals is necessary for developing efficient water quality improvement plans. This study investigated how arsenic leaches from different soil and sediment types and responds to hydrologic conditions to identify areas susceptible to arsenic contamination. In this study, batch- and column-leaching tests and sequential extraction procedures were used to examine arsenic leaching processes in detail. The results showed that most arsenic-loaded sediments accumulated in the vicinity of a reservoir inlet, and arsenic in reservoir beds have a higher leaching potential than those from agricultural land and stream beds. Arsenic deposited at the bottom of reservoirs had higher mobility than that in the other soils and sediments, and arsenic leaching was closely associated with the acidity of water. In addition, arsenic leaching was found to be responsive to seasons (wet or dry) as its mobilization is controlled by organic compounds that vary over time. The results suggested that temporal variations in the hydrochemical composition of reservoir water should be considered when defining a management plan for reservoir water quality.
20
Carević, Ivana, Nina Štirmer, Marija Trkmić e Karmen Kostanić Jurić. "Leaching Characteristics of Wood Biomass Fly Ash Cement Composites". Applied Sciences 10, n. 23 (4 dicembre 2020): 8704. http://dx.doi.org/10.3390/app10238704.
Testo completoAbstract (sommario):
Wood biomass ash (WBA) represents an environmental and economic problem for energy producers, and there have been extensive studies of using WBA as a raw material in construction products. This study investigates the leaching characteristics of WBA cement composites based on testing results. Currently, 70% of WBA is landfilled, and the rest is primarily used in agriculture; therefore, this study also addresses the leaching as a component of environmental safety of these two primary WBA management approaches. An analysis of the leaching characteristics of WBA, monolithic, and crushed cement composites is performed by replacing 15% of the cement with WBA. The study was conducted using three WBA samples collected from different power plants. Increased values of leaching from the WBA itself are indicative of potential issues that could occur in the case of its disposal. The study concluded that the WBA could be potentially environmentally acceptable as a raw material in the concrete industry because the heavy metals are stabilized within the cement matrix.
21
Dong, Shengwei, Taian Fang, Jifang Wan, Xuhui Hu, Jingcui Li, Hangming Liu, Dongyang Li e Shaofeng Qiao. "Study on the Effect of the Water Injection Rate on the Cavern Leaching Strings of Salt Cavern Gas Storages". Energies 16, n. 1 (28 dicembre 2022): 344. http://dx.doi.org/10.3390/en16010344.
Testo completoAbstract (sommario):
In the early construction of cavern leaching in salt cavern gas storages, the inner leaching tubing is often blocked, frequently leading to the bending deformation phenomenon of the leaching strings, which can result in out-of-control cavity shapes. It is difficult to monitor the stress, vibration, and morphological changes of the inner tube during the construction of a cavity. There are few research results in this field at home and abroad, and they are limited only to preliminary explorations of the mechanism or summaries and speculation of the field operation. In this paper, an experimental device for testing the dynamic characteristics of salt cavern leaching strings is developed based on the similarity principle. The device is used to simulate two types of operation processes, i.e., the direct and reverse circulation leaching processes. The experimental data are processed using the modal analysis method to obtain the vibration characteristic parameters of the inner leaching tubing in the circulation process with identical flow rates inside the tubing and the annular region. The following main conclusions can be drawn: The circulation mode has no significant effect on the vibration frequency of cavern leaching strings. The deformation characteristics of cavern leaching strings during direct and reverse circulation are identical, featuring maximum deformation at the bottom and minimum deformation in the middle. The maximum deformation of cavern leaching strings during reverse circulation is about 1.5 times that during direct circulation. Through an experimental investigation and analysis, the effects of the water injection rate and the cavern leaching method on the vibration frequency and bending deformation of cavern leaching strings was determined, providing a reference for further solving the bending problem of cavern leaching strings in combination with engineering practice.
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Sakanakura, Hirofumi, e Hiroyuki Ishimori. "Leaching Tests to Identify the Leaching Characteristics of Radioactive Cesium in Solid Wastes". Material Cycles and Waste Management Research 24, n. 4 (31 luglio 2013): 274–80. http://dx.doi.org/10.3985/mcwmr.24.274.
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Ghadiri, Mahdi, Susan T. L. Harrison e Marijke A. Fagan-Endres. "Quantitative X-ray µCT Measurement of the Effect of Ore Characteristics on Non-Surface Mineral Grain Leaching". Minerals 10, n. 9 (23 agosto 2020): 746. http://dx.doi.org/10.3390/min10090746.
Testo completoAbstract (sommario):
In heap (bio)leaching processes, a substantial fraction of the valuable mineral is positioned below the ore particle surface. X-ray micro-computed tomography (μCT) was used to quantify the effect of ore type and structure and operating temperature on the leaching of this mineral, to investigate the rate-controlling factors. Mini-leaching columns containing agglomerated chalcopyrite, pyrite, and malachite ores were scanned by X-ray μCT (13.40 µm resolution) at select time intervals. The leaching of a relatively porous malachite ore was reaction-controlled, with no leaching penetration limitation into the ore particles. For two less porous ore types, the structure and higher porosity of the agglomerate rim and conditions that resulted in the degradation of the full ore matrix structure were found to be the determining variables of the leaching extent and time. In the case of a chalcopyrite ore, an enhancement of copper recovery and sulphide mineral dissolution with increasing temperature was attributable to the increased leaching penetration distance and crack development in addition to thermodynamically expected increased leaching rate. Increasing temperature did not affect the maximum penetration distance for the waste rock containing pyrite, with no crack development observed. Overall increases in iron recovery were due to accelerated leaching rates, though diffusion or mineral access limitations were evident at a higher temperature.
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Zeng, Sheng, Jinzhu Li, Kaixuan Tan e Shuwen Zhang. "Fractal kinetic characteristics of hard-rock uranium leaching with sulfuric acid". Royal Society Open Science 5, n. 9 (settembre 2018): 180403. http://dx.doi.org/10.1098/rsos.180403.
Testo completoAbstract (sommario):
In order to study the fractal dynamic properties of uranium leach mining and discuss the influence of ore crushing on the dynamics of leach mining, uranium mine ore rocks in southern China were selected as the research object and an acid leaching experiment was performed on the ore samples with different fractal dimensions of 1.1, 1.4, 1.7, 2.0, 2.3 and 2.6. In the column leaching experiment, a PVC pipe with an inner diameter of 112 mm and a height of 1500 mm was used. The uranium content was determined by using titanium trioxide that was placed into a 0.1 mg ml −1 standard uranium solution, and a sampling rate of once daily with a 5 ml volume of leaching solution was adopted after 8 h drenching time. The results show that the flow rate of the leaching solution depends on the distribution of the ore's particle size, that is, a larger fractal dimension results in a smaller flow rate. The concentration of the uranium leaching solution reaches a maximum value which subsequently decreases with time on the third day of the experiment, and it seems that the changes in the uranium concentration tend to be stable at around 15 days. Moreover, the concentration seems to increase with the increasing fractal dimension, and the fractal dimension of the ore particle size has a significant impact on the leaching kinetics. When the fractal dimension is between 1.1 and 2.6, the uranium dissolution rate, K , increases with the increasing fractal dimension. The kinetic reaction of the uranium leaching is a liquid–solid one, which is controlled by chemical reactions in the earlier phase. While the middle reaction phase is mainly chemical-diffusion reaction coupling, and the latter part of the reaction is controlled by diffusion. As the fractal dimension increases, the liquid–solid reaction controlled by diffusion appears at earlier phases. When the fractal dimension is greater than 2.0, the time of entering the diffusion control phase only changed little with the increasing of the fractal dimension. At last, a fractal dimension of 2.0 is suggested for the acid leaching of uranium ore crushing.
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Li, Jiafeng, Hongying Yang, Linlin Tong e Qiao Chen. "Mineralogical Characteristics and Refractory Properties of Arsenic-bearing Gold Concentrate". Journal of Physics: Conference Series 2539, n. 1 (1 luglio 2023): 012097. http://dx.doi.org/10.1088/1742-6596/2539/1/012097.
Testo completoAbstract (sommario):
Abstract The arsenic-bearing gold ore in Anhui, China is an extremely refractory gold ore, and the cyanide leaching rate of gold concentrate is only 30%. The mineralogical factors of the low leaching rate were discussed by process mineralogical analysis. The results demonstrate that the gold concentrate contains 20.30 g/t gold, 3.39% arsenic, 29.80% sulfur, and 4.10% iron. Gold exists in the occurrence states of metallic mineral-wrapped gold, gangue mineral-wrapped gold, and fissure gold, which account for 64.90%, 8.31%, and 26.79% respectively. Pyrite, arsenopyrite, realgar, sphalerite, and pyrrhotite are the main metallic minerals in the gold concentrate. Among them, pyrite accounts for 51.20%, and arsenopyrite accounts for 24.30%. Gangue minerals include feldspar, sericite, quartz, calcite, and chlorite. Among them, feldspar, sericite, and quartz account for 30.30%, 22.70%, and 22.10% respectively. In addition, the grain size distribution and distribution characteristics of various minerals are obtained, and the texture and structure of the gold ore are analyzed. Pyrite and arsenic phase are the main factors causing the low gold leaching rate. The presence of carbonate minerals and clay minerals also has an effect on the rate of gold leaching. The oxidation pretreatment can increase the gold leaching rate to about 94%. The findings provide a theoretical foundation for the selection of manufacturing techniques in businesses and play an important guiding role in the development of similar ores.
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Li, Zai Bo, San Yin Zhao, Xu Guang Zhao e Mao Hua Zen. "Leaching Behaviors of Chemical Components from Steel Slag". Advanced Materials Research 634-638 (gennaio 2013): 245–48. http://dx.doi.org/10.4028/www.scientific.net/amr.634-638.245.
Testo completoAbstract (sommario):
The leaching characteristics of chemical components from converter steel slag were studied through circulating leaching experiments. Results show that the most quality of leaching is CaO, SiO2 is the second and Al2O3 is the least. Analyzing the leaching process and experimental results, it can conclude that the leaching kinetics is controlled by intra-paticle diffusion. The leaching process can be described by shrinking unreacted core model.
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Zhang, Kailai, Liqun Xu, Liting Qiu, Jiacheng Tan, Chao Yang e Kai Zhang. "Numerical Analysis of Concrete Gravity Dam Seepage Characteristics Evolution considering the Calcium Leaching Effect". Advances in Civil Engineering 2021 (19 novembre 2021): 1–21. http://dx.doi.org/10.1155/2021/9042863.
Testo completoAbstract (sommario):
During the long-term service life of hydraulic structures, the calcium compounds in cement-based materials decompose in the aqueous environment, leading to the continuous change of seepage characteristics. To study the influence of calcium leaching on the concrete dam seepage characteristics, we proposed a new mathematic model of the cement-based material calcium leaching model under advection-diffusion-driven leaching. A solid-liquid nonequilibrium model is adopted to model the decomposition of calcium hydroxide (CH) and calcium silicate hydrate gel (C-S-H). To calculate the porosity more accurately, the proposed model takes the effect of different calcium compound decomposition on the porosity increase in consideration, respectively. Shimantan dam is selected for the three-dimensional (3D) calcium leaching analyses. The 3D finite element model of this dam is analyzed using COMSOL Multiphysics software that is based on the finite element method. Based on the proposed model, seepage characteristics evolutions of the Shimantan dam are studied. Good agreement between the numerical results and the monitored data indicates the accuracy of this simulation. The result shows that after 100 a leaching duration, the uplift pressure increases by 40.8%, and the leakage quantities of the dam body and foundation increase by 48 and 17 times. The rise of uplift pressure and leakage changes caused by curtain deterioration are the main influences of calcium leaching on the dam seepage. The parameter sensitivity results show that it is necessary to reduce CH content in cement-based materials to obtain better calcium leaching durability. This model and simulation results can guide the operation of concrete dams under advection-diffusion-driven leaching.
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Wang, Degao, Jianwei Lu, Jian Wu, Bo Li e Ndhlovu Kataza Nyasha. "Enrichment Characteristics of Hazardous Trace Elements in Feed Coal and Coal Ash in Huaibei Area under Leaching". Toxics 11, n. 4 (26 marzo 2023): 308. http://dx.doi.org/10.3390/toxics11040308.
Testo completoAbstract (sommario):
This research focused on the hazardous elements in the main coal seam of Huaibei coalfield, China. Through collecting 20 feed coal samples from different coal seams of nine coal mines in the region, and combining with XRF, XRD, ICP-MS, and sequential chemical extraction, the mineral composition and the contents of major elements and HEs for feed coal were analyzed. Compared with previous research results, the enrichment characteristics of HEs in feed coal were revealed. The leaching behaviors of Se, Hg, and Pb in feed coal and coal ash under different leaching conditions were analyzed in depth by using a leaching device independently developed. Results showed that, compared with Chinese coals and World coals, the content of other elements, except Se, Sb, Hg, and Pb, in feed coal of Huaibei coalfield were at the “Normal” level, and no “Low” level elements were found; as the acidity of leaching solution decreased, the relative leaching rate of Se (LSe) was gradually increasing, while the LHg and LPb were not obvious; the LSe in feed coal and coal ash had a great relationship with the modes of occurrence of Se. The difference in the Hg content in the ion exchange state in feed coal may be an important reason for the difference in Hg leaching behavior. However, the content of Pb in feed coal had little influence on its leaching behavior. The modes of occurrence of Pb determined that the LPb in feed coal and coal ash was not high. The LSe increased with the increase in acidity of leaching solution and leaching time. The leaching time was the main influencing factor of the LHg and LPb.
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Li, Changming, Haifeng Cheng, Yali Cao, Cong Ding, Dongyang Jia, Shunbo Zhao e Chen Yang. "Dissolution Characteristics and Microstructure of Waste Pisha Sandstone Minerals in Alkaline Solutions". Minerals 13, n. 3 (8 marzo 2023): 378. http://dx.doi.org/10.3390/min13030378.
Testo completoAbstract (sommario):
Waste Pisha sandstone (WPS) is the main damming material for the check dam in the Loss Plateau of northwest China. The dissolution characteristics of WPS in alkaline solutions were investigated as a basis for studying WPS modification materials and revealing the modification mechanism to further study the pozzolanic activity of WPS and the development of cementitious materials for concrete utilizing WPS. In this paper, WPS was milled and calcined at 600 °C, 700 °C, and 800 °C, respectively. After that, the activated WPS was immersed in 0.05, 0.1, 0.5, 1.0, 2.0, and 5.0 M NaOH solutions for leaching tests. The two curing temperatures of 20 °C and 80 °C were set, respectively. The ion concentration of Si, Al, and Ca in the alkaline solutions was determined using chemical titration, silicon–molybdenum blue colorimetric method, and graphite furnace atomic absorption spectrometry, respectively. After the leaching tests, the residues of WPS were characterized using XRD and SEM-EDS. The results show that the concentration of each ion in the leachate did not increase with leaching time but showed fluctuating variations with leaching time. Mechanochemical activation and thermal activation will promote the dissolution of minerals in alkaline solutions and increase the leaching efficiency of Si. However, the soluble Si in the leachate is not able to generate further gelling-like substances, limited by the total amount of available Ca in the mineral. WPS can dissolve more ions in higher concentrations of a NaOH solution, but the mineral crystallinity of its residue will be reduced. Higher curing temperatures can greatly increase the leaching efficiency of Si in a short time, which is better than thermal activation, and it can also promote the generation of newborn minerals and increase the crystallinity of minerals in WPS after leaching.
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Ozaki, Masa-aki, Haruki Watanabe e Bernd Wiebusch. "Characteristics of heavy metal release from incinerated ash, melted slag and their re-products". Water Science and Technology 36, n. 11 (1 dicembre 1997): 267–74. http://dx.doi.org/10.2166/wst.1997.0420.
Testo completoAbstract (sommario):
Several leaching tests were conducted for sewage sludge and their re-products to investigate the characteristics of heavy metal release. Regarding incinerated ash, leaching tests indicated that the concentrations of Se and As in leachate were relatively higher than those of other heavy metals. The ratio of As extracted into leachate varied according to the leaching test method. The lower the pH value of leachate after the leaching test, the higher the concentration of As observed. The data using the Holland method had the highest value, and 19.7–46.9% of As was extracted into leachate. If the ratio of concentration in leachate to content (L/C) by the Holland method is 1.00, that of other methods was 0.20–0.43. Regarding melted slag, leaching tests indicated that the heavy metal concentrations in leachate were very low. Regarding re-products, leaching tests indicated that the heavy metal concentrations in leachate were much lower than those of incinerated ash and melted slag. The diameter effect of crushed sample was investigated by the Holland method. 0.3–0.7% of As was extracted from the crushed samples having diameter 20–50 mm and 0.9–2.6% of As was extracted from the samples having diameter less than 5 mm.
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Wang, Panpan, Yunzhe Cao, Bin Yang, Huilong Luo, Tian Liang, Jingjing Yu, Aizhong Ding et al. "Leaching Characteristics of Heavy Metals in the Baghouse Filter Dust from Direct-Fired Thermal Desorption of Contaminated Soil". International Journal of Environmental Research and Public Health 19, n. 24 (8 dicembre 2022): 16504. http://dx.doi.org/10.3390/ijerph192416504.
Testo completoAbstract (sommario):
After thermal desorption, the total amount of heavy metals (HMs) is enriched in baghouse filter dust. To further understand the related environmental impact, the leaching characteristics under various conditions must be explored. Therefore, this study aimed to examine the leaching characteristics of seven HMs in the dust generated in the direct-fired thermal desorption process and to compare the differences in heavy metal leaching characteristics in the soil before and after thermal desorption. The leaching characteristics and bioaccessibility of seven HMs—arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), nickel (Ni), and zinc (Zn)—were analyzed in dust and in soil before and after thermal desorption. The activity of HMs in dust was strong. Therefore, environmental effects and effects on human health should be considered in the treatment of soil and dust after thermal desorption.
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Koddenberg, Tim, Christian Brischke, Lukas Emmerich e Annika B. E. Kick. "Properties of Mexican bloodwood (Haematoxylum campechianum L.). Part 1: anatomical and colourimetric characteristics". Holzforschung 76, n. 4 (10 febbraio 2022): 330–38. http://dx.doi.org/10.1515/hf-2021-0186.
Testo completoAbstract (sommario):
Abstract Bloodwood (Haematoxylum campechianum L.) native to Central America has been known as dye source since the prehistoric times by the Maya. Nowadays, bloodwood is increasingly used for plantations but its use for furniture, flooring, or fencing is only of regional importance. The reason is seen in lacking knowledge of its properties. To expand that knowledge, this Part 1 of the two-part study series investigated the anatomy and the discolouration due to leaching of heartwood of H. campechianum. Anatomical characteristics were described qualitatively and quantitively using scanning electron microscopy and X-ray micro-computed tomography. Detailed wood anatomical data are presented, together with numerical analyses of cell parameters. Apart from wood anatomy, colourimetric analyses were obtained after 10 leaching cycles. The colour change of the wood due to water exposure was determined measuring in CIE L*a*b* colour system. In addition, the extinction of the leachate was determined spectrophotometrically after each leaching cycle. The resulting colour change was evaluated according to colour change after each cycle. The most prominent change in colour was observed for the first cycle due to leaching. Because of the extensive leaching of extractives, further investigation might address the effect of leaching of water-soluble extractives on adhesion properties of bloodwood.
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Li, Chang, Liugen Zheng, Chunlu Jiang, Xing Chen e Shuaishuai Ding. "Characteristics of leaching of heavy metals from low-sulfur coal gangue under different conditions". International Journal of Coal Science & Technology 8, n. 4 (11 marzo 2021): 780–89. http://dx.doi.org/10.1007/s40789-021-00416-6.
Testo completoAbstract (sommario):
AbstractCoal gangue is the main pollution source of mining areas. When coal gangue is stacked and recycled, the heavy metal elements contained in it are released by natural weathering and leaching, which causes damage to the surrounding ecological environment. In this study, the leaching and precipitation characteristics of heavy metals in low-sulfur coal gangue under different environmental conditions were simulated by indoor dynamic leaching experiments, which provided a theoretical basis for environmental restoration of the mining area. The conclusions are as follows: higher heavy metal content in low-sulfur coal gangue is associated with greater, leaching of heavy metals; acidic conditions promote the release of heavy metals in low-sulfur coal gangue; and more precipitation is associated with better release of heavy metals from the low-sulfur coal gangue.
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Liu, Defeng, Wenxin Yan, Zhenyue Zhang, Wenda Guo e Ruan Chi. "Study on Continuously Weakening Mechanism of Heap Leaching Velocity of Weathered Rare Earth Ores with the Increase of Ore Burial Depth". Minerals 13, n. 4 (21 aprile 2023): 581. http://dx.doi.org/10.3390/min13040581.
Testo completoAbstract (sommario):
The column leaching experiments, CT, numerical simulation and fractal theory were adopted to study the continuously weakening mechanism of the heap leaching velocity of weathered rare earth ores with the increase of ore burial depth. The variation characteristics of pore structure and the seepage law of solution in ore samples at different depths during leaching were explored, respectively. The results showed that the variation of characteristic parameters of the pore structure in the lower ore samples was the main reason for the decrease in the leaching velocity. For the lower ore samples after leaching, the number of pores with a pore volume of less than 0.01 mm3 and a pore radius of less than 0.8 mm increased, while pore connectivity, the fractal dimension of the pore shape, the ratio of pore length to width and pore throat length reduced. The solution paths of the upper and middle ore samples were concentrated while that of the lower samples were few, even interrupted. The pore pressure of the ore samples decreased after leaching, especially that of the lower ore samples. The research results are helpful to enrich the basic theory on the heap leaching of weathered rare earth ores.
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Sarmah, Purbashree, Yuya Nakase, Takeshi Katsumi, Atsushi Yamawaki, Atsushi Takai, Kiyoshi Omine, Shimon Deguchi, Yoichi Doi e Takeshi Ishiguro. "Mechanical and leaching characteristics of inert waste landfills". Japanese Geotechnical Society Special Publication 8, n. 5 (14 marzo 2020): 164–69. http://dx.doi.org/10.3208/jgssp.v08.j09.
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K. L. Dixon, M. C. Smith, D. L. Thomas e W. G. Knisel. "Leaching Characteristics of Banded and Broadcast Inorganic Tracers". Transactions of the ASAE 36, n. 6 (1993): 1779–88. http://dx.doi.org/10.13031/2013.28523.
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Yuan, Chun-Gang, Qing-Peng Li, Ya-Na Feng e Ai-Ling Chang. "Fractions and leaching characteristics of mercury in coal". Environmental Monitoring and Assessment 167, n. 1-4 (15 luglio 2009): 581–86. http://dx.doi.org/10.1007/s10661-009-1074-7.
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Aiban, S. A. "Leaching characteristics of a fine-grained calcareous sediment". Quarterly Journal of Engineering Geology and Hydrogeology 40, n. 3 (agosto 2007): 251–66. http://dx.doi.org/10.1144/1470-9236/06-011.
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Zumsteg, R., M. Plötze e A. M. Puzrin. "Leaching Characteristics of Chemicals from Conditioned Tunnel Muck". Journal of Geotechnical and Geoenvironmental Engineering 144, n. 2 (febbraio 2018): 06017016. http://dx.doi.org/10.1061/(asce)gt.1943-5606.0001790.
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Lin, Cheng-Fang, e Hwa-Wey Huang. "Leaching Characteristics of Solidification System of C3A/CuO". Journal of Environmental Engineering 122, n. 4 (aprile 1996): 323–26. http://dx.doi.org/10.1061/(asce)0733-9372(1996)122:4(323).
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Peng, Xin, Yinger Deng, Xiangda Zhang, Lu Liu, Jian Hu, Xianqian Duan, Zhicheng Wei, Qiuping Feng e Ke Shen. "The leaching characteristics of common toxic elements in phosphogypsum". Geochemistry: Exploration, Environment, Analysis 20, n. 4 (30 luglio 2020): 473–79. http://dx.doi.org/10.1144/geochem2019-062.
Testo completoAbstract (sommario):
Phosphogypsum (PG) is an acid by-product from the production phosphate fertilizers that is produced in large amounts all over the world. However, it is challenging to reuse this waste due to the quantities of various impurities in PG and technical restrictions, resulting in PG accumulation, which threatens adjacent environments. To reduce PG storage and safely utilize PG, the aim of our study was to define the leaching characteristics of the impurities present in PG under different conditions. We found that (1) different leaching experiments showed different leachate profiles (including pH and electrical conductivity values of leachate), which indicated that the liquid/solid (L/S) ratio, temperature, oscillation strength, particle size, and pH have remarkable effects on the concentration of leached impurities; (2) all leachate (i.e. soluble P, fluoride, Zn, Pb, As, and Hg) extraction concentrations were significantly more sensitive to the effect of the L/S ratio and pH than the effect of the other conditions; and (3) the leaching concentration was strongly influenced by pH, and a strong correlation among soluble P, F, As, and Hg concentrations in the leachate was demonstrated by a correlation analysis. In the present study, we revealed a systematic leaching mechanism of potential toxic elements in PG and have provided guidance and a reference for PG resource comprehensive utilization and surrounding environment treatment.Supplementary material: Chemical compositions of the phosphogypsum and pairwise Wilcoxon test results are available at https://doi.org/10.6084/m9.figshare.c.5088187
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Zhang, Yijie, Haotian Zhang, Yihang Zhang e Tian Xiujun. "Soil dissolved organic carbon leaching characteristics of the coastal saline seepweed wetlands in the Wuleidaowan national wetland". IOP Conference Series: Earth and Environmental Science 1084, n. 1 (1 ottobre 2022): 012013. http://dx.doi.org/10.1088/1755-1315/1084/1/012013.
Testo completoAbstract (sommario):
Abstract As the most active component of soil TOC (Total Organic Carbon), DOC (Dissolved Organic Carbon) is either adsorbed by the soil and used by plants or transported by soil water into the water column, where it participates in the broader carbon cycle. As a substantial "mobile carbon pool" in soils, its leaching process is an essential pathway for the loss of soil TOC. This paper analysed the investigated the leaching characteristics of soil DOC by simulating leaching in an indoor soil column based on the spatial distribution of soil TOC and DOC contents in order to reveal the leaching and migration characteristics of soil DOC at different depths and its main influencing factors. The DOC content of soil leachate varies somewhat under conditions such as PH and soil phosphorous content. However, the overall trend is that the DOC content of soil leachate generally increases with the depth of the soil layer. The DOC content in the soil leachate gradually decreased with increasing leaching time. In the absence of exogenous carbon recharge, the loss of TOC from the upper layers of the soil was significantly more remarkable due to the prolonged leaching. In addition, soil TOC loss declined after leaching and decreased significantly with increasing soil depth. Because the soil DOC is adsorbed and trapped in other layers during leaching, the DOC in the upper layer was always lost during the leaching test. The experiments used highly concentrated DOC solutions as drench solutions. According to the analysis of the intensity of the fluorescence centres of each soil layer in the three-dimensional fluorescence pattern of the drench solution of each soil layer, the ability of different soil layers to adsorb and retain organic matter of different fractions differs. In addition, the selected soil layers planted with Saline seepweed show a general decreasing trend in the ability to adsorb and retain organic matter as the depth increases.
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Ma, Shao Jian, Gui Fang Wang, Jin Lin Yang, Shao Juan Que, Li Qun Tang e Jin Peng Feng. "Study on Preparation Process of Zinc Ferrite". Advanced Materials Research 201-203 (febbraio 2011): 1736–40. http://dx.doi.org/10.4028/www.scientific.net/amr.201-203.1736.
Testo completoAbstract (sommario):
Zinc ferrite is usually formed during the roasting of zinc sulfide concentrate with high content of iron and reduces zinc recovery during the leaching of zinc calcine. Because it is difficult to find pure zinc ferrite in nature ore resources or in chemicals market, which impedes the investigation of the reaction characteristics of zinc ferrite and the seek of new technologies for zinc ferrite dissolution, so it is of significance to obtain relatively pure zinc ferrite for further research on zinc calcine leaching. This article investigated the preparation process of zinc ferrite based on the dissolution characteristics of a zinc calcine with 19.38% iron and put forward a method to judge the reaction end point during the leaching of zinc calcine to produce zinc ferrite. The results show that the product of zinc ferrite could be prepared through recovering the leaching residue during leaching the zinc calcine under the initial H2SO4 concentration equal to or larger than 160g/L, and that the leaching end point can be judged by comparing the experimental curve of Zn leaching with the zinc theoretical dissolvability curve.
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Lv, Rujie, Yong Wang, Xiuxia Yang, Yangping Wen, Xueming Tan, Yongjun Zeng e Qingyin Shang. "Adsorption and leaching characteristics of ammonium and nitrate from paddy soil as affected by biochar amendment". Plant, Soil and Environment 67, No. 1 (11 gennaio 2021): 8–17. http://dx.doi.org/10.17221/276/2020-pse.
Testo completoAbstract (sommario):
Biochar plays a key role in nitrogen cycling, potentially affecting nitrogen adsorption and leaching when applied to soils. The laboratory experiments were conducted to investigate the adsorption characteristics of rice straw biochar (RSBC) to ammonium (NH<sub>4</sub><sup>+</sup>) and nitrate (NO<sub>3</sub><sup>–</sup>) and the influence of RSBC on leaching characteristics of NH<sub>4</sub><sup>+</sup> and NO<sub>3</sub><sup>–</sup> at different soil depths using multi-layered soil columns. The results showed that the adsorption characteristics were significantly fitted with Freundlich and Langmuir adsorption isothermal curve models. The Freundlich isotherm model indicated that RSBC has relatively higher adsorption capacity and adsorption intensity to NH<sub>4</sub><sup>+</sup> than NO<sub>3</sub><sup>–</sup>. Moreover, the Langmuir isotherm model showed that the maximum adsorption capacity of RSBC to NH<sub>4</sub><sup>+</sup> and NO<sub>3</sub><sup>–</sup> were 31.25 and 10.00 mg/g, respectively. The leaching experiments showed that the contents of NH<sub>4</sub><sup>+</sup> in the leachates from the soil columns showed significant differences at different depths depending on the application amount of RSBC. Compared with CK (0% RSBC amendment), the overall cumulative losses of NH<sub>4</sub><sup>+</sup> via leaching were decreased by 23.3, 35.1 and 13.7% after adding 2, 4 and 6% RSBC, respectively. Correspondingly, the contents of residual soil NH<sub>4</sub><sup>+</sup> in the soil column were increased significantly with the RSBC amendment at different depths. However, the losses of NO<sub>3</sub><sup>–</sup> via leaching from the soil columns could not be retarded obviously by RSBC. Therefore, the application of an appropriate biochar rate is beneficial to retard the losses of soil NH<sub>4</sub><sup>+</sup> from paddy soil.
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Setina, Janina, V. Akishins e L. Petersone. "Correlation of Surface Characteristics and Thermal Conductivity of High Silica Glass Fibre Materials". Advanced Materials Research 39-40 (aprile 2008): 193–96. http://dx.doi.org/10.4028/www.scientific.net/amr.39-40.193.
Testo completoAbstract (sommario):
The new generation of high silica materials with high thermal resistance was created by leaching of chopped glass fibre. These materials with low thermal conductivity are inert to the majority of chemical reagents, resistant to organic and mineral acids, weak alkali, water and highpressure steam. High silica chopped strand mats are non-woven fabrics designed for using in a wide range of insulation and protection applications at temperature till 11000C. The technology and quality of leaching process of initial Si-Al-Na glass widely depends on quality of fibre surface characteristics, i.e., roughness of surface of glass filaments. The surface roughness of the fibre before leaching is a function of chemical durability, therefore it depend on content of Al2O3. The thermal conductivity (within 20…10000C) of chopped strand mats directly depends on the surface roughness. The morphology and compositional profiles of surface of glass fibre before and after leaching were investigated using AFM, SEM, X-ray microanalysis and X-ray powder diffractometer. The different defects for fibre with content of Al2O3 <2.5% and high roughness namely cracking and crystalline deposits of Na2SO4 on top and into pores of fiber after leaching have been identified. The presence of sodium ions on surface of fibre decreases the heat insulation properties of mats. The structure of glass filaments surface was investigated in order to clarify the influence of surface characteristics on thermal conductivity of high silica glass fibre non-woven fabrics.
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Yuan, Mengna, Huiqing Xiang, Yang Tong, Kanggen Zhou, Changhong Peng e Wei Chen. "Spectroscopic Tracking of the Characteristics of Microplastic-Derived Dissolved Organic Matter". Separations 10, n. 2 (1 febbraio 2023): 101. http://dx.doi.org/10.3390/separations10020101.
Testo completoAbstract (sommario):
Microplastic-derived dissolved organic matter (MP-DOM) has received increasing attention in recent years. In this study, the fluorescence excitation-emission matrix (EEM) combined with parallel factor analysis (PARAFAC) was used to track the leaching behavior of polyethylene (PE), polyvinyl chloride (PVC), polypropylene (PP), polyethylene terephthalate (PET), and polystyrene (PS) MP-DOM. After seven days of leaching, PVC reached a leaching concentration of 7.59 mg/L, and the other four microplastics reached approximately 4.5~4.7 mg/L. The leaching activity of PVC was considerably more active in an alkaline environment and under UV irradiation. All the fluorescence signals of MP-DOM components were located in the protein/phenol-like fluorescence region. The fact that C1 and C2 were found in every microplastic revealed that these substances took up quite a large proportion of MP-DOM. Protein/phenolic substances in MP-DOM showed different binding ability with different heavy metals, which can be realized from the log K values calculated for Cr3+ (3.99–5.51), Cu2+ (3.06–4.83), Cd2+ (3.76–4.41), and Fe3+ (3.11–5.03). This work introduced more MP-DOM samples, and offered spectroscopic insight into the characteristics and environmental fate of MP-DOM at a molecular level. Furthermore, this study displayed the potential applicability of using the integrated methods to track the MP-DOM formation process and environmental behavior in natural aquatic systems.
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Seniūnaitė, Jurgita, e Saulius Vasarevičius. "Fresh Bottom Ash Characteristics Dependence on Fractional Composition". Mokslas - Lietuvos ateitis 9, n. 4 (11 settembre 2017): 363–70. http://dx.doi.org/10.3846/mla.2017.1064.
Testo completoAbstract (sommario):
Waste incineration process generates two main by-products streams: fly ash and bottom ash. Bottom ash is composed of a variety of oxides, heavy metals and salts. Chemical materials distributed unevenly in different fractions of bottom ash. This study investigates the heavy metals (Pb, Cd) content dependence of bottom ash and fraction composition. Studies were performed with five different fractions (0–2 mm; 2–5.6 mm; 5.6–11.2 mm; 11.2–22,4 mm; 22.4–40 mm) of fresh bottom ash. After a one-step leaching test (distilled water was used as a solvent), was determinate, that highest concentrations of the lead (Pb) (from 0.141 to 0.146 mg/l) are leached from the smallest (0–2 mm 2–5.6 mm) bottom ash fractions particles. Heavy metals concentration in these fractions eluates respectively was 2.83 and 2.91 times higher than the limit value of leaching. The highest concentration of cadmium (4.214 mg/l) was determinate in 0–2 mm fraction bottom ash eluate. concentration of cadmium was 1.40 times higher than the limit value of leaching. It can be concluded that 0–2 mm; 2–5.6 mm fraction bottom ash can’t be used in civil engineering, without pre-treatment (eg. washing or aging).
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Rhee, Seung Whee, e Woo Keun Lee. "Characteristics of Spent Foundry Sand - Loess Mixture as Ceramic Support Materials". Materials Science Forum 510-511 (marzo 2006): 378–81. http://dx.doi.org/10.4028/www.scientific.net/msf.510-511.378.
Testo completoAbstract (sommario):
Spent foundry sand (SFS) from cast iron industry mixed with loess was characterized to recycle spent foundry sand as ceramic support materials. Since SFS mostly consists of sand including binding agents and residue [1], it was used as permeable media, and loess, which has highly adsorptive and reactive properties, was used as support materials Leaching tests such as Korean Leaching Test (KLT) and TCLP (Toxicity Characteristics Leaching Procedure) showed that spent foundry sands from cast iron industry were not hazardous. Turbidity in furan sand was much higher than that in other sands, and turbidity was almost not changed with increasing amount of loess. The order of ORP (oxidation-reduction potential) in spent foundry sands was green sand > furan sand > CO2 sand. ORP was decreased with the amount of sand in furan sand and CO2 sand but was increased with the amount of sand in green sand. Hence, mixture of SFS and loess can be used as ceramic support materials with reductive or oxidative capability.
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Jing, Jianfa, Yufeng Guo, Shuai Wang, Feng Chen, Lingzhi Yang e Guanzhou Qiu. "Recent Progress in Electric Furnace Titanium Slag Processing and Utilization: A Review". Crystals 12, n. 7 (9 luglio 2022): 958. http://dx.doi.org/10.3390/cryst12070958.
Testo completoAbstract (sommario):
Titanium slags produced through ilmenite electric furnace smelting contain 60–80%TiO2, a vital titanium resource in the titanium industry. The processing and utilization of titanium slag is faced with many challenges, such as complex mineral structures, high requirements, severe environmental pollution, and heavy additives and energy consumption. This study aims to review the technologies for the processing and utilization of titanium slag. First, we analyze the characteristics of titanium slag from different regions. Then, we discuss in detail the methods for processing and using titanium slag. The progress in electric furnace titanium slag processing and utilization can be divided into two areas: the preparation of titanium dioxide and high-quality titanium-rich materials. These include H2SO4 leaching, HCl leaching, fluoride leaching, sulfur roasting–leaching, alkaline roasting–leaching, oxide roasting–leaching, oxidation and reduction roasting–leaching, phosphorylation roasting–leaching, and ammonia decomposition leaching. Further development of oxide roasting–leaching for the extraction of titanium from titanium slag is recommended.
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Sun, Yan, Daofang Zhang, Feipeng Li, Hong Tao, Moting Li, Lingchen Mao, Zhujun Gu, Ziyang Ling e Huancong Shi. "The rainfall effect onto solidification and stabilization of heavy metal-polluted sediments". Royal Society Open Science 7, n. 7 (luglio 2020): 192234. http://dx.doi.org/10.1098/rsos.192234.
Testo completoAbstract (sommario):
Rainfall makes impacts on the process of solidification/stabilization (S/S) and the long-term safety of solidified matrix. In this study, the effect of rainfall on solidification/stabilization process was investigated by the rainfall test. The unconfined compressive strength (UCS) and toxicity characteristic leaching procedure (TCLP) were adopted to characterize the properties of S/S sediments before and after the rainfall test. The samples cured for 28 days were selected for semi-dynamic leaching tests with a simulated acidic leachant prepared at pH of 2.0, 4.0 and 7.0. The effectiveness of S/S treatment was evaluated by diffusion coefficient ( D e ) and leachability index (LX). The results indicated that UCS decreased at maximum deterioration rate of 34.23% after 7 days of curing, along with the minimum rate of 7.98% after 28 days by rainfall, with greater than 14 days referred. The rainfall had little effect on the leaching characteristics of heavy metals during the curing process. However, the simulated acid rain made significant impacts on the leaching behaviours of the heavy metals in the S/S materials. All the values of cumulative fraction of leached heavy metals were less than 2.0%, exhibition of good stabilization of cement. Furthermore, the calculated diffusion coefficient ( D e ) for Cu was 1.28 × 10 1 cm 2 s –1 , indicating its low mobility of heavy metal ions in S/S sediments. Furthermore, the calculated diffusion coefficients ( D i ) for Cd, Cu and Pb were 7.44 × 10 −11 , 8.18 × 10 −12 and 7.85 × 10 −12 cm 2 s –1 , respectively, indicating their relatively low mobility of heavy metal in S/S sediments.