Chemical Fractionation and Contamination Intensity of Trace Elements in Stream Sediments at the Sarcheshmeh Porphyry Copper Mine, SE Iran

This paper presents chemical fractionation and contamination intensities of trace elements in stream sediments at the Sarcheshmeh mine, southeastern Iran, which is one of the world’s largest Oligo-Miocene porphyry copper deposits. Evaluation of environmental pollution indices and maximum probable background concentrations revealed that As, Cu, Cd, Mo, Pb, Sb, Se, S, and Zn are highly concentrated in the contaminated sediments, while Cr, Co, Ni, Fe, and Mn show lower enrichment values. Discharges of industrial effluents (especially those contaminated by tailings), reject waste from the semi-autogenous mill, and rock waste drainages are the main anthropogenic contaminant sources. High values of As, Cu, Fe, Mo, Pb, and Zn were associated with the oxidizable, primary sulfide, and residual sediment fractions. Relatively high percentages of Co (>92?%), Cr (>58?%), Cu (>79?%), Fe (>40?%), Mn (>97?%), Ni (>87?%), and Zn (>83?%) in the sediments associated with the rock waste drainages were readily released during the extraction of water-soluble, exchangeable, and carbonate fractions. Sediments that received reject waste drainages were also polluted by As (>351.7?mg?kg^?1), Cu (>1.58?%), Mo (>91.8?mg?kg^?1), Pb (>291.8?mg?kg^?1), and Zn (>762.4?mg?kg^?1). A large percentage of these contaminants were found to be adsorbed and co-precipitated with amorphous Fe-oxides and carbonate phases. The chemical fractionation pattern of the potentially hazardous trace elements corresponded well with the mineralogical composition of the contaminated sediments.     

Evaluation of Metal Attenuation from Mine Tailings in SE Spain (Sierra Almagrera): A Soil-Leaching Column Study

A laboratory study was undertaken using mine tailings and soil columns to evaluate some of the natural processes that can control the mobility of metals at Pb–Ag mine tailings impoundments. The effects of buffering, pH, and salinity were examined with tailings from the El Arteal deposit. Al, Ba, Cd, Cu, Fe, Mn, Ni, Pb, Sr, and Zn were mobilized when the tailings were leached. However, when the mine tailings were placed above alluvial soils, Al, Ba, Cd, Cu, Mn, Pb, and Zn were retained, although Fe and Sr clearly remained mobile. Most of the metal retention appears to be associated with the increase in pH caused by calcite dissolution. The sorption of some metals (Cu, Pb, and Zn) onto oxyhydroxides of Fe and Mn, sulphates, clay materials, and organic matter may also explain the removal of these metals from the leachate.     

西藏某矿厂铁尾矿中重金属形态及迁移潜力分析

以西藏某矿厂两个尾矿库的铁尾矿(TW-1，TW-2)为研究对象，采用《浸出毒性浸出方法 硫酸硝酸法》HJ/T299-2007研究铁尾矿的浸出毒性，以改进的BCR法探讨铁尾矿中9种重金属的形态分布。结果表明：铁尾矿属于一般固体废弃物，铁尾矿中Fe、Mn 、Zn和Cu含量较高。铁尾矿中As含量超出一类用地风险筛选值3倍。TW-1中Cd的浸出浓度超出Ⅱ类水标准。TW-1重金属活性系数的大小为Pb>Cd>Ni>Zn>Cu>Mn>Cr>Fe>As，TW-2重金属活性系数的大小为Pb>Zn>Ni>Cd>Mn>Cu>Cr>Fe>As。综合9种重金属的迁移能力，结果为TW-1重金属迁移潜力大于TW-2。铁尾矿中的Pb、Cu、Cd和Zn的易于迁出态占比超过60%，对环境有潜在的风险。其中Pb以还原态为主，Cu、Cd和Zn以氧化态为主。     

The Impact of Phosphate Mine Tailings on the Bioaccumulation of Heavy Metals in Marine Fish and Crustaceans from the Coastal Zone of Togo

Abstract  About 2.5 million t of sedimentary phosphorite mine tailings, highly enriched with Cd, Cr, Cu, Ni, Fe, F, and Zn, are dumped annually in the coastal waters of Togo without any pre-treatment, causing serious pollution problems in the region. We conducted bioaccumulation investigations on fish and crustaceans sampled from the polluted coastal zone. The highest concentrations of metals in fish and crustacean were found close to the tailings outfall and the values decreased further away from the source of pollution. Compared to the international reference norms for seafood given by the WHO, Cd is enriched 10 to 168 fold, Pb 20 to 107 fold, Cu up to 5 fold, Fe up to 15 fold, and F up to 3 fold.     

煤矸石对铜尾矿中重金属(Zn,Pb,Cd,Cr和Cu)形态及生物有效性的影响

铜尾砂堆积在地表会随着淋溶和风化作用溶出重金属元素,对环境产生一定危害,其生态修复的关键是进行基质改良,进行植物修复。通过黑麦草盆栽实验,将淮南煤矸石添加入铜尾砂,探讨矸石对铜尾砂中重金属行为的影响。结果表明:矸石添加能显著提高铜尾砂p H、有机质和养分水平(总氮、总磷和总钾),缓解尾矿砂贫瘠环境。矸石添加后,铜尾砂中Zn,Pb,Cd和Cu的交换态和碳酸盐结合态重金属逐步向铁锰结合态、有机结合态和残渣态转化(除个别处理Pb和Cu残渣态),铜尾砂中有效态Zn,Pb,Cd和Cu浓度不断降低,从而降低了黑麦草中相应重金属浓度,总体表现为铜尾砂-黑麦草系统内Zn,Pb,Cd和Cu生物活性降低效应。然而,由于矸石中Cr浓度相对铜尾砂偏高,其添加会引起尾矿砂中有效态Cr浓度及Cr迁移性增加而增大黑麦草对Cr的吸收。因此,煤矸石可对尾矿砂中Zn,Pb,Cd和Cu产生一定稳定化作用,而虽然矸石内源性Cr会释放到铜尾砂,其也可被黑麦草富集,由此,煤矸石可视为一种潜在的废弃物改良剂,对铜尾砂具有一定生态改良潜力。     

Tailings Weathering and Arsenic Mobility at the Abandoned Zgounder Silver Mine,Morocco

The abandoned Zgounder Mine (Morocco) was exploited for Ag from 1982 to 1990 and generated nearly 490,000 t of mill tailings before it was closed without being reclaimed. The tailings contain low concentrations of sulfide (mainly as pyrite, sphalerite, and galena) and carbonates (mainly dolomite). Silicates (muscovite, albite, chlorite, labradorite, actinolite, and orthoclase) occur in high concentrations. The most abundant trace elements are As, Ti, Fe, Mn, Zn, and Pb. We studied the geochemical behavior of the mine wastes to identify the main factors controlling drainage water chemistry. Particular emphasis was put on sorption phenomena to explain the low As concentrations in the leachates despite significant As levels in the tailings. Weathering cell tests carried out on various tailings produced two types of contaminated drainage: acidic and neutral. The kinetic test leachates contained high concentrations of some contaminants, including As (0.8 mg L^?1), Co (11 mg L^?1), Cu (34 mg L^?1), Fe (70 mg L^?1), Mn (126 mg L^?1), and Zn (314 mg L^?1). Acidity and contaminants in the leachates were controlled by dissolution of soluble salts and Fe hydrolysis rather than sulfide oxidation. Batch sorption tests quantified the significance of As sorption, and sequential extraction showed that most of the As sorption was associated with the reducible fractions (Fe and Mn oxides and oxyhydroxides).     

Lime Treatment of Mine Drainage at the Sarcheshmeh Porphyry Copper Mine,Iran

Laboratory and field treatment tests were performed to evaluate the effectiveness of lime treatment for mitigation of environmental effects of acid mine drainage (AMD) at the Sarcheshmeh porphyry copper mine. AMD associated with the rock waste dumps is contaminated with Al (>36,215 μg/L), Cd (>105 μg/L), Co (>522 μg/L), Cu (>53,250 μg/L), Mn (>42,365 μg/L), Ni (>629 μg/L), and Zn (>12,470 μg/L). The concentrations of other metals (Fe, Mo, Pb, and Se) are low or below detection limits (As, Cr, and Sb). Due to the very high Al and Mn content and the low concentration of Fe, a two-stage lime treatment method was chosen for the laboratory tests. In the first stage, the AMD was treated at four pH set points: 7.5, 8.9, 9, and 10. In the second stage, after removing the sludge at pH 9, treatment was continued at pH 10 and 11. The results indicated that a two-stage treatment method was not necessary because elements such as Al, Cu, Co, and Zn were easily treated at pH 7.5, while complete removal of Cd, Mn, and Ni only required a pH of 10. Increasing pH during the treatment process only caused a slight increase in Al. Field treatment tests support the laboratory results. Lime treatment of highly contaminated AMD from dump 11, using simple low density sludge pilot scale equipment, show that contaminant metals are treatable using this method. The mean treatment efficiency for contaminant metals was 99.4% for Al, % for Cd, 99.6% for Co, 99.7% for Cu, 98.5% for Mn, 99.7% for Ni, 99% for U, and 99.5% for Zn. The optimum pH for AMD treatment by lime was in the range of 9–10. The produced sludge in the treatment process was highly enriched in the contaminant metals, especially Cu (>7.34%), Al (>4.76%), Mn (>2.94%), and Zn (>1.25%). A correlation coefficient matrix indicates that the distribution pattern of the contaminant metals between soluble and precipitated phases is consistent with the hydrochemical behavior of the metals during the lime treatment process.     

广西南丹某尾矿库矿物元素纵向分布规律研究

为了调查广西南丹某尾矿库矿物元素的纵向分布规律,参考相关标准并通过相关性分析、主成分分析、回归分析和通径分析研究了尾矿库内不同深度尾矿的矿物元素特征。结果表明,尾矿中各元素含量随深度变化均存在一定分层,表现出"二次富集"现象,且富集层尾矿表现出较好的工业利用潜力。在矿物元素分布规律的研究中发现Zn、Sb、Cd、Pb、Sn和Cu元素可归为一类,S、Fe和As元素可归为另一类,同一类矿物元素的分布规律相似;各矿物元素之间存在不同程度的相互作用,且发现了较好的拟合模型;通径分析表明S主要受到Fe、Cu和Zn的影响,Fe主要受到S和As的影响,Pb主要受到Sb的影响,Zn主要受到Cd、Cu和Sb的影响,Sn主要受到Zn、Cd和Cu的影响,Sb主要受到Pb和Zn的影响,Cu主要受到Zn、S和Sn的影响,As主要受到Fe、Sn和Cu的影响。综上表明,铅锌尾矿库中矿物元素存在"二次富集"现象,具有较好的工业利用潜力,矿物元素之间存在相互作用,进而影响各矿物元素的分布规律。     

Processing of Phosphate Mine Tailings by Coagulation Flocculation to Reduce Marine Pollution in Togo: Laboratory Tests

Abstract  About 2.5 million t of sedimentary phosphorite mine tailings, highly enriched with trace metals such as Cd, Cr, Cu, Ni, and Zn, are dumped annually in the coastal waters of Togo without any pre-treatment, causing serious pollution problems in the region. We conducted laboratory jar tests of a coagulation-flocculation procedure with coagulants RM45U and AN945MPM to clarify the sludge. The efficiency of the method depends particularly on two factors: the amount of coagulant and the solid concentration of the sludge to be treated. Thus, with a mud concentration of 47.7 g/L, the average optimal amount of the two coagulants was 25 mg/L. With both coagulants, water turbidity passed from 60 x 103 NTU to approximately 3 NTU after clarification with the optimal amount of the two coagulants. RM45U reduced concentrations of Pb by 40%, Zn by 98.8%, Fe by 80.6%, and Cd by 32.8%. AN945MPM reduced Pb by 20%, Zn by 98.5%, Fe by 48%, and Cd by 32.8%.     

A DFT study on the effect of lattice impurities on the electronic structures and floatability of sphalerite

The electronic structures of bulk sphalerite containing 14 typical kinds of impurities were studied by density-functional theory (DFT). The calculated results show that the presence of Cd, Hg, Ga, Ge, In, Ag, Sn, Pb and Sb could increase the lattice parameter of sphalerite. Ag, Sn, Pb, Sb, Cd and Hg impurities narrowed the band-gap and increased the conductivity of sphalerite. Moreover, Mn, Fe, Ga, In, Sn and Sb impurities changed the semiconductor type of sphalerite from p-type to n-type. All of the impurities except Cd and Hg made the Fermi level shift to higher energy and led to the occurrence of an impurity state in the forbidden band.Analysis of the frontier molecular orbital showed that the impurities Mn, Fe, Cu, Ge, Sn, Pb and Sb contributed greatly to the highest occupied molecular orbital (HOMO) and greatly influence the nucleophilicity of sphalerite. On the other hand, the impurities of Fe, Cu, Co, Ni, Cd and Ga greatly contributed to the lowest unoccupied molecular orbital (LUMO) and greatly affected the electrophilicity of sphalerite. The interactions of O₂ and xanthate with sphalerite are discussed. Results suggest that Mn, Fe, Ni, Cu, Sn and Pb impurities favored the oxidization of sphalerite; however, the impurities of Cd, Hg, Ga and In had the opposite effect. Impurities of Mn, Fe, Co, Ni, Cu, Hg and Pb could enhance the reactivity of xanthate with sphalerite.     

Mineralogical and Geochemical Characterization of Mine Tailings and Pb, Zn, and Cd Mobility in a Carbonate Setting (Northern Tunisia)

Millions of tonnes of Pb–Zn ore flotation tailings and waste rock have been discharged at sites in northern Tunisia without concern for environmental issues. The tailings are dominantly fine grained (<125 μm), with high porosity and permeability. The tailings were characterized to assess base metal (Pb, Zn, and Cd) mobility. The relatively low percentage of iron sulphide and the dominance of carbonates in the matrices of the tailings indicated that only neutral mine drainage is likely. Batch sequential testing showed that the calcium and sulphate, which are the major ionic species in solution, are derived mainly from the dissolution of gypsum and not from neutralization of acidity generated by pyrite oxidation. Yet, despite the carbonate setting, the resultant neutral to slightly alkaline pH, and prolonged weathering, the studied flotation tailings maintain their capacity to release contaminants, notably Zn and Cd, into the environment. The amount of Zn that dissolves (2,400 μg L^?1, on average), though significant, is below the background concentrations in the Mejerda River and the environmental norms established for surface waters. Pb concentrations come close to the standards, but only Cd (18 μg L^?1, on average) sometimes exceeds current river water concentrations and environmental standards.     

Heavy Metals in Stream Sediments from the Coquimbo region (Chile): Effects of Sustained Mining and Natural Processes in a Semi-arid Andean Basin

Abstract.   Active sediments from the Elqui River in Chile were sampled 4 times at 10 sites during 2000. Concentrations of Ag, Ba, Cd, Co, Cr, Hg, Mn, Mo, Ni, Pb, Sr, Ti, V, Al, Ca, Fe, K, Mg, Na, P, and S were normal. Zinc levels were clearly high, and those of Cu (hundred to thousands ppm) and As (tens to hundreds ppm) were highly anomalous. Dissolved Cu (0.1-12.7 ppm) and Zn (0.2-2.2 ppm) levels were also very high. The anomalies of the upper tributaries are due to the El Indio–Tambo Au-Cu-As district and large hydrothermal alteration zones at altitudes between 3500–4500 m. Lower on the river, old and active tailing waste deposits and on-going mining operations in the Talcuna Cu (Pb) district are responsible. Partially eroded tailing deposits in the alluvial plain of the Elqui River and its tributaries, and especially in the El Indio-Tambo district, after mine closure in 2000, warrant special attention.     

Risk Assessment and Ranking of Metals Using FDAHP and TOPSIS

The sediment of the Sarcheshmeh copper mine in Iran contains high concentrations of trace metals. In this risk assessment study, criteria such as contamination factor, pollution load index, and geoaccumulation index were used to assess levels of Co, Cu, Mo, Zn, Cr, Mn, Ni, Pb, Ti, and Fe in the mine sediment released to the tailings dam. Expert opinions on the relative importance of each of the indicators were used to assign a final weighting of the criteria using the fuzzy Delphi analytic hierarchy process, and the metals in the sediments of the study area were ranked and clustered using the TOPSIS method. Based on the results, the metals were clustered into 10 categories with copper, iron, and zinc having the highest pollution and critical risk.     

鞍山某铁矿区土壤重金属形态分布及生物有效性分析

研究鞍山某铁矿区周边土壤中5种重金属（Cd、Pb、Cu、Zn和Ni）的全量和形态分布,采用风险评价编码（RAC）法及次生相与原生相分布比值（RSP）法对元素生物有效性和环境风险进行评价。研究结果表明,该区土壤中Cd和Ni全量超出了国家二级标准,Pb、Cu和Zn未超限,但在土壤中富集明显;各重金属生物有效态占比的大小顺序为Cd > Pb > Ni > Zn > Cu,Cd元素生物活性最高且毒性最强;5种重金属的RAC值大小依次为Cd（40.62%）> Pb（21.60%）> Ni（16.31%）> Cu（12.16%）> Zn（9.74%）,RSP值大小依次为:Cd（1.31）> Pb（1.06）> Zn（0.94）> Ni（0.71）> Cu（0.39）。结合总量、生物有效性及形态学评价,该矿区土壤重金属Cd是生物活性最强、环境风险最高的元素,其次是Pb;Ni的生物有效性较低,但其全量已超标,因此应对该区Cd、Pb和Ni给予特别关注。      

煤矿酸性矿井水中有害元素的迁移特性

利用电感耦合等离子质谱（ICP-MS）、离子色谱（IC）和X射线衍射（XRD）等方法研究了马兰煤矿酸性矿井水及其沉淀物的化学成分和物相组成,并通过吸附解吸实验和PHREEQC水化学模拟计算研究了典型酸性矿井水样品中Pb,Th,U,Be,Zn,Ni,Co,Cd,Cu,As,Cr,V,Ba等有害元素的迁移特性.研究表明：① 煤矿酸性矿井水中SO^2-₄,Fe,Mn,Al,Pb,Th,U,Be,Zn,Ni,Co,Cu等离子含量较高,对环境存在潜在危害;② 酸性矿井水中有害元素的迁移主要受pH,Fe-Al-Mn含量和水体颗粒物矿物组成的控制;③ Fe,Al和Mn的含量随pH上升而迅速下降,并控制着Pb,Th,U,Be,Zn,Ni,Co,Cu等潜在有害微量离子的迁移行为; ④ 各离子随pH上升被去除的先后顺序为: Th>Fe>Pb >Cr>Al>Cu>Be>U>Zn>As>Cd>Mn>Co>Ni>Ba;⑤ 酸性矿井水中V不能够随pH的升高而去除,反而会有更多的V溶解在水中.     

Contaminated Alluvial Ground Water in the Butte Summit Valley

Abstract.  Ground water in alluvial sediments of upper Silver Bow Creek is chronically contaminated with heavy metals, including Cd, Cu, Fe, Mn, and Zn. Most of this contamination stems from slag, mill tailings, and waste rock from the Butte mining district that had been deposited along the ancestral Silver Bow Creek floodplain. Much of this mine waste is now buried by fill, topsoil, buildings, or parking lots. Although the pH values of most wells in the region are in the 5.5 to 7.0 range, a cluster of monitoring wells near the site of a former mill and smelter contain water that is strongly acidic (pH < 4.5), with extremely high dissolved metal concentrations (Cu up to 750 mg/L; Zn up to 490 mg/L). Ground water discharging from the area is currently collected by a subsurface French drain and conveyed to a treatment facility where lime is added to precipitate metals from solution.     

Geochemical and Mineralogical Characterization of a Pyritic Waste Pile at the Anjir Tangeh Coal Washing Plant, Zirab, Northern Iran

Coal washing at the Anjir Tangeh plant, in Zirab, northern Iran, has produced more than 1.5 Mt of coal wastes. These waste materials were geochemically and mineralogically characterised to guide development of an appropriate remediation scheme. Three vertical trenches up to 4 m deep were excavated from the coal waste pile surface and 25 solid samples were collected at 0.5 m intervals. The samples were analysed for total concentrations of 54 elements, paste pH, SO ₄ ^?2 , CO ₃ ^?2 , and HCO₃ ^?. The lowest pH values were measured at a depth of 0.3 m. The upper portion (1 m) of one profile was moderately oxidised, while oxidation in the other two profiles did not extend more than 0.8 and 0.5 m beneath the pile surface. The waste piles have low acid-producing potential (15–21.87 kg CaCO₃/t) and high values of acid-neutralizing potential (0.06–96.2 kg CaCO₃/t). Fe, Al, S, Na, Mn, Pb, Zn, Cd, and Ag increased with increasing depth, while Mo, Sr, Zr, and Ni decreased with increasing depth. The results show pyrite oxidation at depth and subsequent leaching of the oxidation products. Mn, Zn, Cu, Pb, Ag, and Cd are the most important contaminants of concern at this site.     

生态地球化学评价水质样品中多元素分析方法研究

将电感耦合等离子体光谱(ICP-AES)和质谱(ICP-MS)相结合,直接测定生态地球化学评价水质样品中的20多种元素(Ca、Mg、P、Fe、Mn、A l、Ba、Sr、S i、L i、Be、V、Cr、Ti、Co、N i、Cu、Zn、Mo、Cd、Sn、Pb),方法灵敏、快速、简便。     

Pilot-scale Studies of Different Covers on Unoxidised Sulphide-rich Tailings in Northern Sweden: the Geochemistry of Leachate Waters

Abstract.  Leachate water quality from covered and uncovered unoxidised sulphide-rich tailings in six pilot-scale (5x5x3 m³) test cells was monitored during 2004 and 2005. The covers consisted of a layer of clayey till, sewage sludge, apatite or Trisoplast (a commercial mixture of tailings, bentonite, and a polymer). All layers were protected by an unspecified till except in one reference cell, where the tailings were left open. All leachate waters showed near-neutral pH as a result of neutralization by calcite in the tailings and by Ca(OH)₂ added prior to deposition. Average dissolved sulphur concentrations in the leachates were ≈ 600 mg L^-1, except in the cell with sewage sludge (300 mg L^-1). The source of sulphur was mainly pyrite oxidation, but residual sulphur probably remained from the enrichment process. The near-neutral pH favoured precipitation of metal-(oxy)hydroxides with subsequent removal of trace elements such as Cd, Cu and Pb (< 15 μg L^-1) from the solutions. High concentrations of Co, Mn, Ni, and Zn were found in leachates from the apatite, Trisoplast, and uncovered tailings cells. High As concentrations were found in the leachates in the sewage sludge and clayey till cells. The lowest metal concentrations, redox potential, and highest pH were found in the sewage sludge cell. Decreased elemental metal concentrations during 2004 suggest improved performance over time.     

Removal of Metals and Acidity from Acid Mine Drainage Using Liquid and Dried Digested Sewage Sludge and Cattle Slurry

The metal removal and neutralization capacities of digested sewage sludges from municipal wastewater treatment plants, cattle slurry (liquid manure), and Biofert granules (dried granular anaerobic sludge) were compared under batch conditions using synthetic AMD (pH 2.8) containing high concentrations of Al, Cu, Fe, Mn, Pb, and Zn (100, 15, 270, 15, 2, and 30 mg/L, respectively). The effects of contact time and solids concentration were examined. Metal removal was variable for all materials. Contact time had a significant effect, with total removal often increasing over the experimental time interval (i.e. 30 min to 24 h). Removal efficiency (%) was generally highest for Cu, Pb, and Al, while Mn and Zn were the least removed. Cattle slurry was the best material for metal removal, with the following maximum removals at a solids concentration of 12.9 g/L: Cu >98 %, Al >98 %, Fe >60 %, Mn >18 %, Pb >96 %, and Zn >60 %. Metal removal using digested sewage sludge reached 88 % for Al, 98 % for Cu, 94 % for Pb, and 30 % for Zn. Neutralization was complete within 30 min after AMD was mixed with digested sludges or cattle slurry, with the pH reaching a maximum of 5.5 with the slurry. In contrast, neutralization by the Biofert granules only reached equilibrium after 300 min, and pH remained <4.0 except at high solids concentrations. It appears that recycled waste-derived organic materials can neutralize AMD and remove dissolved metals by adsorption and precipitation, creating a more treatable waste stream or one that could be discharged directly to surface water. Potential methods of safe disposal of metal-enriched organic materials are discussed.