Acid Mine Drainage at the Abandoned Kettara Mine (Morocco): 1. Environmental Characterization

The Kettara site (Morocco) is an abandoned pyrrhotite ore mine in a semi-arid environment. The site contains more than 3 million tons of mine waste that have been deposited on the surface without concern for environmental issues. Tailings were stockpiled in a dyke and pond and in piles, over an area of about 16 ha, and have generated acid mine drainage (AMD) for more than 24 years. The mine waste and secondary precipitates from this mine were characterized using geochemical and mineralogical techniques. The Kettara wastes contain 1.6–14.5 wt% sulfur, mainly sulfide minerals (e.g., pyrrhotite, pyrite, chalcopyrite, galena, and sphalerite). The main gangue minerals were goethite, quartz, chlorite-serpentine, talc, muscovite, and albite. Carbonates occur at very low quantities (less than 1 wt%). The most abundant heavy metals were Cu, Zn, Cr, Pb, Co, As, Cd, and Ni. Acid–base accounting static test results showed that all the samples have low values of acid-neutralizing potential (NP) (0–9 kg CaCO3/t). The mine waste has high acid-producing potential (AP) (51–453 kg CaCO3/t). Abundant secondary mineralogy is present, consisting mainly of halotrichite, goethite, jarosite-hydroanion, hydroniumjarosite, starkeyite, gypsum, alunite, copiapite, butterite, and coquimbite. Hardpans, which can prevent water infiltration to fresh tailings beneath and thereby lessen the rate of sulfide reactivity, were observed during sampling of the fine tailings. Mineralogical analysis indicated that the cementitious phase of the hardpan is mainly goethite. The alteration observed in the tailings pond does not extend more than 5–15 cm.     

酸性矿山废水（AMD）地球化学工程防治技术

酸性矿山废水（AMD）的地球化学工程防治技术,意指根据AMD的生成机理,采用地球化学方法（包括AMD预测评价、覆盖和渗透反应栅等技术）对AMD（及重金属）污染进行预防控制和治理的集成技术。该项技术具有长效、低成本、易施工,以及原位治理等特点,适用于处理排放持续时间长、富含毒性重金属的酸性污水,值得在我国的金属硫化物矿山开发应用。     

Passive Treatment of Acid Mine Drainage at the La Extranjera Mine (Puertollano, Spain)

In southern Spain, coal seams typically contain pyrite. The mines there are characteristically contaminated by the presence of diverse metals disolved in acidic water. An experimental passive system, containing an anoxic limestone draine, organic matter and wetlands, was constructed to assess how best to inprove the water chemistry. The procedure we used is reported on here so others can learn from what we did.     

Acid Mine Drainage Flowing from Abandoned Gas Wells

Abstract  In northwestern Pennsylvania (USA), numerous abandoned natural gas wells are producing artesian flows of Fe-contaminated water. The origin of the polluted water has been generally assumed to be brines from the gas-producing sands. We sampled 20 artesian discharges where iron staining was conspicuous. The waters were not brines, but were more characteristic of acid mine drainage (AMD). The dominant cations were Fe, Ca, and Mg, while the dominant anion was sulfate. The study area has a long history of coal mining in the lower Allegheny formation; however, the coal beds are generally at higher elevations than the discharges. We propose that AMD formed in the coal mines is infiltrating into lower aquifers, moving outside the lateral limits of mining, and using abandoned gas wells as conduits to the surface. While flowing through the underlying sandstones, the AMD chemistry is modified by contact with siderite, the dominant carbonate mineral in this stratigraphy. This would suggest that current remediation strategies that emphasize plugging the pollution-producing gas wells may be ill-advised because the source of the polluted water is more shallow than currently assumed.     

用浸出工艺回收酸性矿山废水沉淀渣中金属元素

酸性矿山废水沉淀渣的处置一直是废水处理工程面临的难题。以广东省大宝山矿槽对坑尾矿库外排废水处理厂产生的沉淀渣为例,开展沉淀渣中有价金属元素酸浸与回收试验。淀渣铁、锰、铜、锌、镍、铅品位分别为40 919.6,14 320.6,4 681.4,7 557.4,149.3,360.9 g/t,杂质成分主要为石英、方解石。在硫酸浓度为20%、固液比为0.33 g/mL、浸出时间为8 h、浸出温度为30 ℃条件下,铜、锌、镍、铅、锰和铁的浸出率分别为99.49%、21.41%、51.21%、4.45%、55.86%、34.25%。采用硫酸浸出工艺回收沉淀渣中有价金属元素在技术经济上可行,同时可缓解废水处理厂的环保压力。     

Geochemistry and Mineralogy of Mill Tailings Impoundments from the Panasqueira Mine (Portugal): Implications for the Surrounding Environment

Selected geochemical results are presented from a study of the Panasqueira mine (Sn–W mineralization), which is one of the Portuguese test sites for the e-EcoRisk project (). These data permit a better understanding of the dynamics inherent to leaching, transport, and accumulation of some elements (mainly As, but also Cu, Pb, Zn, and Cd) in different sampling media and their environmental relevance. Stream sediment and water samples were found to be contaminated by the stored waste material in the tailing ponds; this effect could be observed for a considerable distance downstream.     

矿山酸性废水治理HDS工艺技术研究

HDS处理工艺是一种高效底泥循环回流技术,在矿山酸性废水治理中具有提高药剂利用率、提高污泥浓度、改善污泥沉降浓缩特性等优点,在国外矿山酸性废水治理中具有广泛的应用,在国内仅有部分试验研究。通过实验室试验以及结合研究资料对HDS处理工艺在矿山酸性废水的治理过程机理进行了研究,同时对技术研究进展及应用等方面进行了现状分析。     

Downflow Limestone Beds for Treatment of Net-Acidic, Oxic, Iron-Laden Drainage from a Flooded Anthracite Mine, Pennsylvania, USA: 2. Laboratory Evaluation

Acidic mine drainage (AMD) containing elevated concentrations of dissolved iron and other metals can be neutralized to varying degrees by reactions with limestone in passive treatment systems. We evaluated the chemical and mineralogical characteristics and the effectiveness of calcitic and dolomitic limestone for the neutralization of net-acidic, oxic, iron-laden AMD from a flooded anthracite mine. The calcitic limestone, with CaCO₃ and MgCO₃ contents of 99.8 and <0.1 wt%, respectively, and the dolomitic limestone, with CaCO₃ and MgCO₃ contents of 60.3 and 40.2 wt%, were used to construct a downflow treatment system in 2003 at the Bell Mine, a large source of AMD and baseflow to the Schuylkill River in the Southern Anthracite Coalfield, in east-central Pennsylvania. In the winter of 2002–2003, laboratory neutralization-rate experiments evaluated the evolution of effluent quality during 2 weeks of continuous contact between AMD from the Bell Mine and the crushed calcitic or dolomitic limestone in closed, collapsible containers (cubitainers). The cubitainer tests showed that: (1) net-alkaline effluent could be achieved with detention times greater than 3 h, (2) effluent alkalinities and associated dissolution rates were equivalent for uncoated and Fe(OH)₃-coated calcitic limestone, and (3) effluent alkalinities and associated dissolution rates for dolomitic limestone were about half those for calcitic limestone. The dissolution rate data for the cubitainer tests were used with data on the volume of effuent and surface area of limestone in the treatment system at the Bell Mine to evaluate the water-quality data for the first 1.5 years of operation of the treatment system. These rate models supported the interpretation of field results and indicated that treatment benefits were derived mainly from the dissolution of calcitic limestone, despite a greater quantity of dolomitic limestone within the treatment system. The dissolution-rate models were extrapolated on a decadal scale to indicate the expected decreases in the mass of limestone and associated alkalinities resulting from the long-term reaction of AMD with the treatment substrate. The models indicated the calcitic limestone would need to be replenished approaching the 5-year anniversary of treatment operations to maintain net-alkaline effluent quality.     

Acid-Base Accounting: A Geochemical Tool for Management of Acid Drainage in Coal Mines

Acid-base accounting tests are generally used as a screening tool to delineate and define the geochemical character of different rocks. Geochemical investigations indicated that the rocks of the study area could be grouped as either acid producing or acid neutralizing. An experiment conducted in the laboratory indicates that allowing the acid mine water to drain through friable, alkaline sandstone neutralizes the mine water. This may be an inexpensive option to use at this site.     

煤矿酸性矿井水形成机理的研究进展

煤矿酸性矿井水是全球采矿业面临的最严重的环境问题之一。分析酸性矿井水的形成机理及其研究进展,并从化学和生化作用两方面来分别论述,详细地介绍氧化亚铁硫杆菌对黄铁矿的氧化作用,探讨当前研究中存在的问题和今后的发展方向。     

德兴铜矿酸性水处理调控系统优化

德兴铜矿为亚洲最大的露天铜矿山,采区边坡、采矿作业面及废石场等产生的酸性废水污染源点多面广,酸性水水质水量变化大,因而酸性水处理系统调控难度大。主要阐述德兴铜矿通过优化矿山酸性水处理调控系统,采取源头削减、过程控制、末端治理的方法,达到控制和减少酸性废水产生和排放,提高酸性水的处理能力。     

Operational Lessons Learned During Bioreactor Demonstrations for Acid Rock Drainage Treatment

The US Environmental Protection Agency’s Mine Waste Technology Program (MWTP) has emphasized the development of biogeochemically-based treatment technologies for mitigation of acid rock drainage (ARD). Progressive technology demonstrations by the MWTP over the past 15 years have resulted in improved operation of sulfate-reducing bacteria (SRB) bioreactors. Although using SRB to treat ARD is now fairly widespread, it was uncommon in the early 1990s when the MWTP used this innovative biotechnology. The first and longest running demonstration was an in situ bioreactor installed within the flooded subsurface workings of the Lilly/Orphan Boy Mine in 1994. The second project, at the Calliope Mine, compared the performance of several SRB bioreactor configurations and operational attributes, including lime pretreatment and reactor temperature. The third demonstration, at the Golden Sunlight Mine, consisted of two treatment steps with a recycle stream. The fourth project was an investigation of existing bioreactor designs and resulted in an improved bioreactor configuration. Significant findings included: (1) a mineshaft could be used as a long-term, in situ bioreactor, (2) SRB thrive in temperature extremes, (3) sulfide recycle effectively avoids contact of ARD with bacterial populations, and (4) ideal bioreactor substrate provides short-term and long-term nutrients, good support matrix, and enhanced permeability.     

Waste rock dumping optimisation using mixed integer programming (MIP)

Despite the fact that waste rock hauling and dumping comprises a large proportion of the cost of materials handling in an open pit mine, little detailed planning is devoted to optimising waste rock dumping. The lack of such planning could result in long-term exposure of potential acid forming (PAF) waste rock, causing acid mine drainage (AMD), which would incur ongoing collection and treatment costs. A waste rock dumping plan that not only minimises hauling costs, but also involves the encapsulation of PAF waste rock to minimise AMD, would benefit a mining operation economically and environmentally. In order to create such a plan, two new mixed integer programming (MIP) models are formulated and tested with a five-year mining schedule. Optimised dumping plans are automatically generated, which detail the dumping location for each mining block. A manual approach is also attempted, and comparison shows that the MIP models have obvious advantages in error prevention, faster solution time and cost saving, by up to 9.5%.     

完善监管体系 实现煤矿安全抽采

随着煤层气开发步伐不断加快,安全管理将是煤层气抽采企业工作的重中之重。结合煤层气抽采企业安全管理现状,通过落实"从零开始、向零奋斗"的安全理念,坚持科学发展,紧盯一线安全,扎实做好基层安全管理工作,建立完善安全管理,技术创新和施工质量三大体系,切实抓好关键部位安全管理,进一步落实安全责任,健全监管机制,推动企业安全稳定持续发展。     

Performance of a Natural Wetland Treating Acid Mine Drainage in Arid Conditions

Abstract  A wetland naturally formed in the discharge from a copper mine tailing impoundment in Rajasthan, India. The wetland is abundantly vegetated. This study investigated changes that occurred in the seepage as it travelled 180 and 380 m (P₁ and P₂) through the wetland. The pH increased from 6.17 to 7.10 at P₁ and 7.34 at P₂ in the pre-monsoon season, 6.53 to 7.36 at P₁ and 7.77 at P₂ in the post-monsoon season, and from 6.20 to 6.63 at P₁ and 6.89 at P₂ in the winter. Contaminant removal at P₂ ranged from 40 to 95%.     

紫金山含铜酸性废水硫化法治理工业运用研究

研究硫化法新工艺从紫金山含铜酸性废水中回收铜工业化运行。经过研究硫化钠与硐坑水接触反应15 min反应完全,ORP控制在150~180 mV,硐坑水中铜金属回收率大于95%,回收金属经济效益最佳,同时处理后的溶液达到国家Ⅰ类水排放标准。该法有利于降低废水治理成本,提高铜资源综合利用率,有较好的经济效益和社会效益。     

Column Kinetic Tests Assessing Geochemical Behavior of Mine Wastes in the Jerada Coal District (Morocco)

The Jerada anthracite mine in Morocco was abandoned in 2001 after producing approximately 20 million tonnes of solid waste. The acid generating potential of these wastes was determined by performing tests on five samples collected from relatively older and more recent waste deposits. No carbonate minerals were identified. Pyrite was the only sulphide mineral observed and much of it had been completely transformed into Fe-oxides. Analysis of the waste indicated low levels (<1 %) of Ca and Mg, while Fe and Al concentrations generally exceeded 5 %. Modified Sobek static tests and column kinetic tests were conducted for 24 months. The static test results were not conclusive (20 <net neutralising potential <20 Kg CaCO₃/t). Leachates from the kinetic tests for three of the five samples showed an initially acidic pH, while those of the remaining two became acidic by the end of the tests. Sulfate concentrations (SO₄ ^2?) decreased over time from 5000 to 200 mg/L.     

自燃煤矸石吸附煤矿酸性废水矿物学特性研究

针对煤矿酸性废水污染问题,采用SEM、XRD和FTIR等分析测试手段,对吸附煤矿酸性废水前后的自燃煤矸石、Na OH改性自燃煤矸石和SRB协同自燃煤矸石样品进行矿物学特性研究。结果表明:自燃煤矸石通过表面孔隙吸附作用和发生配位反应,将煤矿酸性废水中的离子以小颗粒的形式沉积在自燃煤矸石表面。Na OH改性过程溶出自燃煤矸石表面的部分物质,使煤矸石表面出现大量孔隙。对比XRD谱图和红外光谱图可知,自燃煤矸石中的石英和钠长石等矿物成分在吸附煤矿酸性废水时起到了一定的作用。SRB协同自燃煤矸石过程对自燃煤矸石结构成分的影响比Na OH改性过程影响大,附着在煤矸石表面的SRB不仅影响自燃煤矸石表面的矿物质成分,形成黑色硫化物颗粒,还可以直接处理煤矿酸性废水,进一步提高对煤矿酸性废水的处理效果。     

Microbial Growth and Action: Implications for Passive Bioremediation of Acid Mine Drainage

Abstract.  Due to the variable environmental nature of mine water, several species of bacteria are important in the generation of acid mine drainage (AMD) and in bioremediation treatment technology. Enzymatic metal transport and transformation allow bacteria to survive in high-metal environments and to oxidize, reduce, and exude metals. For example, the enzymes Cr (VI) reductase and cytochrome-c3 hydrogenase allow Pseudomonas sp. to reduce Cr (VI) to less toxic Cr (III). Much more toxic organomercuric compounds are transformed by Pseudomonas fluorescens and Escherichia coli, using the enzymes organomercurial lyase and mercuric reductase. The role of bacteria in the AMD environment is not yet fully understood and consequently researchers should pay attention in this field.     

SRB协同自燃煤矸石处理煤矿酸性废水试验

针对煤矿酸性废水中金属离子含量高、易造成环境污染等问题,采用自燃煤矸石、NaOH改性自燃煤矸石和SRB协同自燃煤矸石对煤矿酸性废水中SO42-、COD、Fe2+和Mn2+进行动态吸附试验研究。结果表明：3种处理方式对煤矿酸性废水中待测离子的处理效果为：SRB协同自燃煤矸石作用>NaOH改性自燃煤矸石>自燃煤矸石。其中,装有SRB协同自燃煤矸石的3号柱运行稳定后对煤矿酸性废水中SO42-、COD值、Fe2+和Mn2+的平均降低率分别为69.05%、72.06%、99.02%和38.29%。