Parastrephia quadrangularis: A Possible Alternative to Inhibit the Microbial Effect on the Generation of Acid Mine Drainage

Mine Water and the Environment - The role of iron- and sulfur- oxidizing microorganisms in the generation of acid mine drainage (AMD) from sulfide ores and tailings is widely recognized. The...     

铅锌尾矿中砷的迁移转化特征对比分析

本研究对三铅锌尾矿中砷的含量、形态、环境风险进行分析评价,并结合产酸试验和静态浸出试验研究砷在各铅锌尾矿中的迁移转化特征和影响因素差异。结果表明：1)调查尾矿中砷含量较高,同时砷的形态有明显差异,其中SXD尾矿99%以上为残渣态,而MY尾矿中砷的非残渣态占到54%以上,TD尾矿中虽然残渣态砷占到88%,但由于尾矿中砷含量很高,故其非残渣态总量也较高。2)调查各铅锌尾矿中的砷具有中~重度生态危害,对此类尾矿库后期利用不能直接进行用于农用地用途的开荒复垦,将对农产品带来严重风险。3)结合砷的总量、生物有效性形态、产酸特性和砷的浸出率综合分析,MY尾矿在各尾矿中砷的含量高、活性最高、生物可利用性强,同时该尾矿含硫高,极易产酸,在酸性条件下尾矿中砷的可移动性加强,因而其砷的潜在生态环境风险最高；SXD尾矿砷含量最低,且尾矿中活性砷含量最低、生物可利用性不强,但由于其易产酸特性,在AMD作用下尾矿中砷的可移动性增强,生态环境风险加剧；TD尾矿砷含量最高,同时也具备相当高占比的活性态砷,但是由于其含硫低,酸缓冲能力强,属于不易产酸的尾矿,因而在一定程度上抑制了尾矿中活性砷的迁移转化,但在强碱性条件下,会促进尾矿中相对稳定的硫化砷溶解、解吸,从而向外环境迁移。4)对于不同类型铅锌尾矿中砷污染的防控或生态修复要结合尾矿产酸特性和赋存砷的生物有效性,采取不同的抑酸或固化/稳定化措施；同时考虑到在西南地区地表径流和垂直入渗是砷污染迁移的主要途径,因而必须加强尾矿库的规范设计、建设与管理,必要时采取阻隔措施。     

硫化矿尾矿资源化利用研究现状及展望

硫化矿尾矿储量增长过快,且利用率低,造成了其堆存严重、占地面积大等问题,给社会和环境带来了极大危害,因此硫化矿尾矿的资源化利用愈发受到重视。通过综合论述硫化矿尾矿的现状和危害,阐明了硫化矿尾矿多途径利用的必要性,并根据其组分和性质特点,从作为建材原料、化工产品、尾矿再选和尾矿充填四个方面论述了硫化矿尾矿的资源化利用途径。其中,硫化矿尾矿作为建材原料可以用来生产水泥、混凝土制品、建筑用砖、微晶玻璃和陶瓷;生产的化工产品包括硫磺、工业硫酸、冶金熔剂、耐火材料和金属镁等;尾矿再选可以通过传统选矿(重、磁、浮)和生物浸出的方法来实现,缓解了矿产资源短缺的现状;尾矿充填有效避免了采空区渗漏、塌陷等安全事故。对硫化矿尾矿的资源化利用进行总结梳理,可为其后续研究提供一定参考。     

Valorisation of acid mine drainage treatment sludge as remediation component to control acid generation from mine wastes,part 1: Material characterization and laboratory kinetic testing

In operating mines, acid mine drainage (AMD) is often treated using lime treatment. This process generates a significant amount of sludge that contains metal hydroxide precipitates, gypsum, and unreacted lime. The sludge may have interesting geotechnical and geochemical properties to be used as a part of covers (oxygen barriers) to prevent AMD generation from waste rocks and tailings. The main results of a project aiming to evaluate the use of sludge from the Doyon mine site (Canada) as a material in mine site rehabilitation are presented. The first part of the project involved detailed characterization of sludge, waste rock, and tailings samples. Then, laboratory column leaching tests were performed to evaluate the performance of the mixtures to control AMD produced by tailings and waste rocks. It was found that a sludge–waste rock mixture placed over waste rock reduces the metal loads in the column effluent, which remained acidic, as well as a mixture of sludge and tailings deposited over tailings can reduce metal content in effluents from tailings.     

Valorization of acid mine drainage treatment sludge as remediation component to control acid generation from mine wastes,part 2: Field experimentation

The possibility of using acid mine drainage (AMD) treatment sludge as a cover component to control AMD generation from mine wastes was investigated through laboratory characterization and kinetic column testing (companion paper). The results showed that mixtures of sludge and waste rock, and sludge and tailings, may be integrated in an AMD prevention and control strategy at Doyon mine site (northwestern Quebec, Canada). In order to further investigate these scenarios in realistic climatic conditions, instrumented field test cells were installed on site to evaluate the performance of the mixtures to control AMD generation from tailings and waste rock under natural field conditions. The main findings from two seasons of monitoring are presented in the paper. The waste rock-sludge mixture placed over waste rock was able to reduce the generation of AMD from the waste rock, therefore confirming lab results, and was able to produce a neutral effluent with low concentrations of dissolved metals. The tailings-sludge mixture placed over tailings, with an evaporation protection layer, maintained a high volumetric water content and reduced sulphide oxidation from the tailings as exhibited by a neutral effluent. Monitoring of the field cells will continue to provide valuable information on the possible sludge valorization options.     

A brief survey of current surface waste disposal practices in the metal mining industry

ABSTRACT

Tailings ponds are a common method of mine waste disposal. Technical as well as environmental aspects of surface disposal of metal mine wastes are briefly reviewed The construction of tailings ponds require a broad range of parameters from geotechnical aspects to effluent treatment and reclamation procedures to be taken into consideration. Working with low grade deposits, which require intense grinding, in addition to the presence of sulphide minerals pose difficulties to the disposal of tailings. Government regulations call for reclamation procedures to be drawn-up prior to the commencement of the mining activities. Generation of Acid Mine Drainage (AMD) is one of the most important problem that a metal mine operation can face. Successful reclamation programs depend on an extensive and detailed water management procedure.

This paper reviews the environmental as well as technical aspects that need to be incorporated into the design and construction of a tailings pond facility to minimize and possibly eliminate potential environmental hazards. Current design of disposal facilities must comply with the existing guidelines and regulations which are also reviewed in this paper.     

The selective oxide system™: Acid drainage treatment that avoids the formation of sludge

Conclusion  The feasibility and economics of this technology for AMD is yet to be established through pilot-scale studies, but it offers the potential of compact, economical treatment suitable for concentrated AMD seeps, drainage from acidic tailings ponds, active mine effluent, and acidic iron-rich industrial wastewater. Applicability to other contaminated waters is being investigated.     

Mercury Partitioning and Behavior in Streams and Source Areas Affected by the Novo-Ursk Gold Sulfide Tailings (West Siberia,Russia)

We studied the behavior of mercury in acid mine drainage (AMD) and in portions of the Ur River affected and non-affected by AMD near the Ursk sulfide tailings (Siberia) before (2007–2009) and after (2011–2019) the beginning of tailings reprocessing operations. Mercury occurs in water as dissolved plus colloidal (Hg_dc) and colloidal (Hg_C) species or is adsorbed on suspended particles (Hg_susp). The mercury species were classified as either reactive (Hg_R) or non-reactive (Hg_NR), depending on their capacity to reduce to Hg⁰ by reacting with SnCl₂. The composition and pH of the AMD and river waters change downstream of the AMD input. Mercury concentrations ranged from 1.8 to 89 μg/L (for the entire monitoring period) and increased with AMD pH. High-pH conditions are unfavorable for the precipitation of jarosite, which can adsorb Hg from water, and thus mercury remains mobile. Hg_NR is more abundant than Hg_R in the river and in AMD particulates. Non-reactive mercury in the river water is associated with CH₃Hg⁺, which correlates with total organic carbon (TOC), while Hg in the AMD samples is bound to HgS_(s), m-HgS_(s), HgSe_(s), and Hg-jarosite. Hg_R species are associated with particulates in all water bodies as Hg⁰_(liq), Hg(OH)_2(aq), HgCl_2(aq), and Hg²⁺ adsorbed by OH groups on the surfaces of mineral grains. Judging by the TOC concentration and the pH and Eh of river water, which local people use for fishing, Hg is prone to methylation upstream and downstream of the AMD input. The Hg enrichment of local surface waters is due to both a naturally elevated background in a Hg-rich province and to the mining and processing operations.

     

我国硫化铜矿选矿技术现状及进展

硫化铜矿是世界铜资源的最主要来源之一,高效开发利用硫化铜矿资源,对保障世界及我国铜资源可持续供应具有重要意义。综述了近年来我国硫化铜矿选矿技术领域的发展现状,指出了硫化铜矿选矿工艺流程不断精细优化,选矿药剂开发及应用更加注重绿色高效,大型及新型装备不断推出,尾矿综合利用及资源化技术更加得到重视的特点。另外,推动"互联网+矿物加工"、"大数据+矿物加工"发展,开展"基因矿物加工工程"研究,实现研究方式与生产转化的创新性发展,是硫化铜矿选矿技术领域的一个全新课题。     

大宝山多金属硫化矿尾矿综合利用途径研究

大宝山是我国华南大型的含硫化矿物多金属矿山。对该矿山尾矿的研究表明,尾砂中富含黄铁矿、磁黄铁矿、闪锌矿、黄铜矿、方铅矿等金属硫化物矿物及石英、黏土等,其中金属元素Zn具有回收价值。根据尾砂的成分特征和现有尾矿回收利用技术,本研究针对大宝山金属硫化物尾矿提出一种综合利用途径,即首先对尾砂进行筛分和重选,分离轻、重矿物。针对重矿物,通过浮选富集回收金属元素Zn,通过氧化焙烧回收硫,通过氯化焙烧回收其它金属元素以及磁化回收铁矿物。重选后的轻矿物可以直接利用和筛分利用。该工艺实现尾矿资源化的同时不会对环境造成污染,可以达到无尾矿矿山的目标。     

从选矿尾矿中回收有价元素的试验研究

针对某选矿厂尾矿进行了铜、硫和钨综合回收的试验研究。该尾矿储量大,尾矿中铜、钨含量较低,含硫较高,针对该尾矿性质,采用浮选—重选联合工艺流程回收其中的铜、硫和钨。全流程试验获得的试验指标为:铜精矿铜品位22.02%、回收率74.39%,硫精矿硫品位35.24%、回收率87.26%,钨精矿钨品位65.73%、回收率50.86%。     

硫化矿尾矿堆的温度变化和动态淋溶规律研究

为研究硫化矿尾矿对环境的潜在影响和危害，采用硫化矿尾矿直接浸润实验，研究了硫化矿尾矿堆放中内部温度的变化特性；利用动态柱式淋溶实验，研究了硫化矿尾矿在不同淋溶条件下的铅锌重金属离子溶出规律。结果表明，硫化矿尾矿堆的内部温度随堆放时间的延长而升高，到第25～30天时达到最高值；浸润液的pH值对尾矿堆内部温度存在显著影响，酸性越强，尾矿堆内部温度越高。在酸性、碱性动态淋溶条件下，铅、锌离子都有一定的溶出浓度，酸性越强，越有利于离子溶出，离子溶出浓度随淋溶时间延长而降低；与Pb^2 相比较，Zn^2 的溶出受淋溶液pH值及淋溶时间的影响更大，对强酸性淋溶很敏感。此外，尾矿对不同淋溶液的pH值有较强的缓冲能力，只有较强酸度和较长时间的淋溶时，这种缓冲能力可被削弱。     

Ranking and scoring potential environmental risks from solid mineral wastes

The overall environmental performance of minerals beneficiation operations, in addition to their significant energy demand, is largely a function of the success or failure of waste management strategies to minimise the long-term impacts associated with the disposal of vast volumes of solid waste. Whilst forecasting such impacts, particularly in the early stages of a project, is arguably the most important element in an environmental performance assessment, it remains the most challenging. This paper describes a generic methodology which has been developed for ranking and scoring solid waste constituents on the basis of their hazard-forming potential and chemical behaviour under disposal conditions. The approach is demonstrated for the case of typical porphyry-type copper sulfide tailings. The predictive approach developed here is consistent with the screening phase of risk-based environmental assessment protocols, and is considered to be a vital and integral part of reliably quantifying the environmental life cycle impacts of solid mineral wastes.     

Laboratory Evaluation of the Use of Alkaline Phosphate Wastes for the Control of Acidic Mine Drainage

Pyrrhotite tailings at the abandoned Kettara mine site in Morocco are producing acid mine drainage (AMD). We investigated the use of alkaline phosphate waste (APW) rock from a nearby operating open-pit phosphate mine to control the AMD. The neutralizing potential of the APW, using the Paktunc method, was estimated between 500 and 680 kg CaCO₃/t. In laboratory column tests, the addition of 15 wt% APW to the coarse Kettara tailings produced leachates with significantly lower acidities and metal concentrations than unamended controls. The high calcium concentration in the flushed solutions indicates that calcite was responsible for the neutralization. Dolomite dissolution seems to be negligible and fluorapatite was stable under the testing conditions. It was also observed that when the treated solution comes in contact with unweathered Kettara coarse tailings, the pH becomes acidic, although the metal concentrations remain low.     

铜矿山老尾矿综合回收铜金银浮选技术研究

针对某铜矿尾矿库堆存的老尾矿铜氧化率高及部分硫化铜表面存在不同程度的氧化等特点,采用表面处理与活化及高效捕收剂浮选技术强化表面(半)氧化硫化铜浮选。闭路试验获得了铜品位12.02%、含金9.02 g/t、含银82.72 g/t、铜回收率51.22%、金回收率54.72%、银回收率23.87%的铜精矿。     

Effect of Ore Mineralogy and Bedrock Lithology on Metal Loading Rates and Acid-Mine Drainage: Bayhorse Creek,Idaho and the North Fork of the American Fork River,Utah

Metal contamination of the water in two streams was investigated at the Ramshorn Mine along Bayhorse Creek in Idaho, and the Pacific Mine along the North Fork of the American Fork River in Utah. The studies were conducted to determine what remediation measures should be implemented at each site to reduce metal loads in the streams. Discharge measurements and chemical analyses of filtered and unfiltered water samples allowed dissolved and total metal loads to be calculated. Copper, Fe, Mn, Pb, Zn, and As were found at both sites, and Cd also was present at the Utah site. Of these, Fe had the highest dissolved and total loading rates at the Ramshorn Mine, with Mn and Zn having intermediate rates; Fe and Zn had the highest loading rates at the Pacific Mine. Hydrous ferric oxides, particularly ferrihydrite, are abundant at both sites. Pyrite is the iron source at the Pacific Mine, while it is siderite at the Ramshorn Mine. The lack of sulfide at the latter site inhibits acid mine drainage (AMD) formation, and the presence of dolomite provides abundant alkalinity to neutralize any AMD that might be generated. PHREEQC was used to gain insight into the metal phases and oxidation states, to calculate saturation indices, and to perform surface sorption modeling. The results suggest that most of the metals at both sites are transported in the suspended rather than dissolved state, As occurs exclusively in the less toxic As⁵⁺ form, and several metals are likely sorbed to ferrihydrite. Based in part on the results of these studies, the US Forest Service removed the tailings at the Pacific Mine site, but only capped and regraded the tailings pile at the Ramshorn Mine.

     

矿山酸性废水抑酸技术研究现状与展望

矿山开采及闭矿产生的酸性矿井水、固废堆场产生的酸性淋滤液对矿山生态环境造成了严重的影响，系统梳理与总结相关研究成果对进一步推动酸性矿山废水的治理具有重要意义。本文综述了阻氧覆盖、表面钝化、杀菌处理和微生物抑酸技术的方法原理与应用，分析了不同方法的优缺点和适应性。分析结果表明，抑制矿山废水酸化的方法主要包括物理化学法和微生物法；物理化学抑酸技术能够一定程度上从源头抑制AMD的产生，但存在适用条件限制、二次污染风险、材料易失效等缺点；目前微生物抑酸主要是通过铁还原菌、硫酸盐还原菌、复合型厌氧生物膜等抑酸微生物抑制AMD的产生，但大多处于研发和试验阶段。本研究基于金属硫化矿物微生物催化氧化产酸机理，提出利用“微生物间拮抗与竞争作用”筛选高效抑酸微生物，探索矿山酸性废水抑酸处理新方法。     

Acid Mine Drainage at the Abandoned Kettara Mine (Morocco): 2. Mine Waste Geochemical Behavior

Weathering and humidity cell tests were used to predict the potential for acid mine drainage (AMD) and to estimate the mineral reaction rates and depletion of fine and coarse tailings from the abandoned Kettara mine, Morocco. The geochemistry of the fine and coarse mine wastes was similar and, as expected by static tests, the wastes produced significant amounts of AMD. The sulfate production rate of both fine and coarse tailings was very high (2,000–8,000 and 2,400–560 mg SO₄/kg/week, respectively) during the first weeks of kinetics tests. After 9 weeks, sulfate release became low, ranging between 600 and 78 mg SO₄/kg/week for fine tailings and 500–120 mg SO₄/kg/week for coarse tailings. Effluent water samples had low pH (2.9–4.2) and elevated concentrations of acidity, sulfate, iron, copper, and zinc. Most or all of the dissolved K, Na, Al, Mg, and Si in the AMD result from the acidic dissolution of silicates (chlorite, talc, muscovite, and albite). Fine tailings produce much higher concentrations of acidity and sulfate than coarse tailings. However, due to greater transport of oxygen and water within the coarse waste, coarse tailings could be of greater environmental significance than fine tailings. The coarse waste continued to release acid after 378 days of leaching, whereas the fine tailings naturally passivates. These laboratory results agree with field observations; the upper profile of the coarse waste rock dam is highly oxidized (75 cm) whereas oxidation in the fine tailings does not extend more than 5–15 cm beneath the surface. A comparison between weathering and humidity cell tests indicated that the general trend of dissolution of metals was essentially similar for both methods. However, sulfate depletion rates were higher for the weathering cell tests. These tests indicate that the Kettara tailings piles and dam will continue to release acid for a long time unless remedial action is taken.     

某选铜尾矿硫回收工艺研究

某选铜尾矿含硫较高,主要硫化物为磁黄铁矿、黄铁矿等,由于在选铜作业时可浮性受到抑制,因而重点对硫化矿物浮选的活化剂和捕收剂进行了条件试验,最终确定的1粗1精1扫、中矿顺序返回流程处理该含硫2.46％的选铜尾矿,可获得硫品位为35.04％、硫回收率为83.90％的硫精矿.     

A Comparison Between Kinetic Test Results and Natural Weathering: The Abandoned Kettara Mine Tailings Pond

More than three million tons of sulfide tailings were discarded without any protection for more than 36 years at the since-abandoned Kettara mine. The impact of these tailings as well as the coarse wastes disorderly dumped on the surface site is highlighted by the elevated sulfate levels in the wells downstream of the wastes. Kinetic tests carried out on these sulfide tailings over 10 years ago, showed similar trends in metal dissolution despite large difference in test duration (21 and 53 weeks for the weathering and humidity cell tests, respectively). 40% of the sulfate release occurred in the first 3 weeks of the humidity test. However, in this study, the elevated sulfate levels in the groundwater was shown not be linked to the tailings, where the original sulfide material is still present under an oxidized layer of 10 cm–1.2 m. Thus, kinetic test results should not be extrapolated to field scale without accounting for site-specific factors, especially particle size and climate.