广东凡口Pb-Zn尾矿中重金属的表生地球化学行为及其对矿山环境修复的启示

通过分级提取实验 ,结合矿物成分和化学成分分析 ,对广东凡口铅锌尾矿的新尾矿和 1号尾矿库不同氧化程度尾矿的矿物组成、重金属含量及其形态进行了研究和对比 .新尾矿中的黄铁矿含量很高 (约 3 1% ) ,铅锌的含量分别高达 0 7%和 1 2 %以上 ,重金属元素主要赋存于金属硫化物中 .1号尾矿库样品中的黄铁矿含量 <10 % ,重金属元素也明显低于新尾矿 .在表层氧化带 (硬化层 ) ,硫化物的快速氧化导致大量次生矿物沉淀 ,锌大量吸附于 (氢 )氧化铁表面 ,可迁移性大 ;铅则主要形成次生难溶矿物 (如铅矾 ) ;次氧化带以硫化物的缓慢淋溶作用为主 ,难以形成次生矿物 ,Pb、Zn的流失比例大于 70 % .常用于矿山环境治理的尾矿覆盖方法往往使尾矿处于次氧化环境 .上述研究结果表明 ,这些方法不一定能够阻滞污染元素的迁移 .此外 ,本次研究采用Dold提出的分级提取法 ,发现方铅矿的溶解主要发生在第 2步 (提取液 :pH =4 5 ,1moL L- 1 NH4 Ac) ,而其它硫化物的溶解主要在第 6步 ,这可能是Ac- 与Pb2 + 的络合作用所造成的 ,表明提取液中含Ac- 的分级提取方法不宜用于评价铅的活性     

Hydrogeochemical and mineralogical characteristics related to heavy metal attenuation in a stream polluted by acid mine drainage: A case study in Dabaoshan Mine, China

Dabaoshan Mine, the largest mine in south China, has been developed since the 1970s. Acid mine drainage (AMD) discharged from the mine has caused severe environmental pollution and human health problems. In this article, chemical characteristics, mineralogy of ocher precipitations and heavy metal attenuation in the AMD are discussed based on physicochemical analysis, mineral analysis, sequential extraction experiments and hydrogeochemistry. The AMD chemical characteristics were determined from the initial water composition, water-rock interactions and dissolved sulfide minerals in the mine tailings. The waters, affected and unaffected by AMD, were Ca-SO₄ and Ca-HCO₃ types, respectively. The affected water had a low pH, high SO₄^2- and high heavy metal content and oxidation as determined by the Fe²⁺/Fe³⁺ couple. Heavy metal and SO₄^2- contents of Hengshi River water decreased, while pH increased, downstream. Schwertmannite was the major mineral at the waste dump, while goethite and quartz were dominant at the tailings dam and streambed. Schwertmannite was transformed into goethite at the tailings dam and streambed. The sulfate ions of the secondary minerals changed from bidentate- to monodentate-complexes downstream. Fe-Mn oxide phases of Zn, Cd and Pb in sediments increased downstream. However, organic matter complexes of Cu in sediments increased further away from the tailings. Fe³⁺ mineral precipitates and transformations controlled the AMD water chemistry.     

铅锌尾矿中重金属在模拟酸雨淋溶下的浸出规律

重金属尾矿污染是世界性难题,污染水体、大气和土壤,对周边的生态环境和人体健康造成严重危害。在我国酸雨范围大且酸雨问题比较严重的背景下,探讨酸雨淋溶下尾矿中重金属的浸出规律将有利于加强我国重金属尾矿的污染控制和管理。采用湖南桃林铅锌尾矿库中的尾矿模拟酸雨条件进行淋溶实验,研究发现重金属Pb、Zn、Cu、Mn含量分别为1252.5,849.4,363.1,280.0mg/kg。其中,Pb、Zn主要以残渣态存在,分别占69.7%和53.8%;Cu主要以有机结合态存在,占67.0%;Mn主要以铁锰氧化态、有机结合态和残渣态存在,共占90.0%。在静态淋溶实验中,固液比越大、模拟酸雨pH值越小,重金属的浸出浓度越大。在动态淋溶实验中,Zn、Mn浸出浓度随时间呈现减小趋势,而Pb和Cu浸出浓度随时间先增大,后减小。     

氧化亚铁硫杆菌生物浸出铅锌硫化矿尾矿及浸出过程中重金属形态分析研究

研究嗜酸性氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans,A.f)对铅锌硫化矿尾矿重金属离子的生物浸出和重金属形态变化有助于了解生物浸出作用的过程变化.通过考察生物浸出体系中不同的矿浆浓度对pH值和浸出尾矿重金属的影响,探究生物浸出过程的重金属形态变化情况.结果表明,生物浸出作用对pH值和尾矿重金属的浸出影响巨大,随着矿浆浓度的增加,pH值下降速率呈现先升高后降低、重金属浸出率也呈现先增加后降低的趋势,最佳的生物浸出矿浆浓度为50 g·L~(-1),Fe和Zn的最佳浸出率分别为85.45%和97.85%.重金属形态分析表明,生物浸出作用对尾矿重金属形态变化产生巨大的影响,随着浸出时间的延长,重金属形态逐渐改变,首先易迁移的重金属被生物浸出,然后稳定的重金属也逐渐被生物浸出.     

几种牧草对铜尾矿重金属的抗性及其微生物效应

铜尾矿是一类重金属含量极高 ,对植物生长产生毒害的生境 .盆栽试验结果表明 ,4种牧草在纯尾矿以及由尾矿和对照土壤组成的混合尾矿上都能生长 ,但植物的长势随尾矿中重金属含量的增加而减弱 ,4种牧草对重金属的抗性依次表现为百喜草 >苇状羊茅 >黑麦草 >狗芽根 .此外 ,Biolog结果显示 ,土壤微生物群落代谢剖面 (AWCD)及群落丰富度、多样性指数与牧草的长势密切相关 ,种植牧草后能明显地提高土壤微生物群落功能多样性 ,提高幅度表现为百喜草 >苇状羊茅 >黑麦草>狗芽根 ,百喜草可望成为金属尾矿植被恢复的先锋牧草 .     

藻菌生物膜胞外聚合物与铅锌尾矿重金属的络合配位作用

矿产资源开采冶炼产生大量尾矿渣,其中富含的可溶性重金属引发的生态环境问题日益突显.铅锌矿是我国重要的矿产资源,尾矿露天堆放使得其富含的可溶性重金属淋溶迁移,对矿区周边地表环境造成严重污染.为探明自然水体环境中的藻菌生物膜与重金属的作用机理,采用三维荧光光谱技术研究干旱区天然湖泊中的藻菌生物膜EPS（胞外聚合物）与铅锌尾矿渣中5种重金属离子的络合配位作用.结果表明:①从藻菌生物膜EPS荧光光谱图中可检测出两个荧光峰,均来源于芳香类蛋白酪氨酸物质;②铅锌尾矿淋滤液中的重金属元素主要包括Pb、Co、Ni、Zn和Cd,且这5种金属离子均能有效淬灭EPS的荧光强度;③荧光淬灭滴定试验得出,Pb2+与EPS的络合能力最强,最大络合常数为4.523 1,最大结合位点数为1.177 5;Cd2+与EPS的络合能力最弱,最大络合常数为1.957 1,最大结合位点数为0.684 8;Co2+、Ni2+和Zn2+与EPS的络合能力相似.研究显示,藻菌生物膜EPS中含有的荧光基团与重金属离子的作用强度与金属离子的类型相关,二者的络合配位作用可能会影响重金属在水环境中的化学形态、迁移、生物有效性和生态毒性.      

铜陵相思谷尾矿用于处理酸性矿山排水的实验研究

铜陵相思谷尾矿是夕卡岩型矿床尾矿的典型代表,以富含碳酸盐为特征.为了考察该尾矿砂在AMD淋滤作用下重金属的迁移行为及用于处理AMD的有效性,研究在自行设计的动态实验柱中填充尾矿砂,在保持进水理化性质不变的条件下对其进行80 d的连续淋滤实验,实验过程中定期检测出水的成分,实验结束后对尾矿砂中元素赋存特征进行分析.结果表明,实验过程中出水pH值始终维持在7.5以上;Cu、Zn、Fe离子浓度分别保持在0.1、0.4、1 mg.L-1以下;尾矿砂的渗透系数逐渐降低,由初始的0.23 cm.s-1降至实验结束时的0.10 cm.s-1;固体中元素赋存形态分析结果表明,进水Cu2+、Zn2+主要通过2种作用被固定:Fe氢氧化物的吸持和自身沉淀(形成碳酸盐).研究发现铜陵相思谷尾矿具有较强的酸中和潜力,在中和过程中不仅不会产生重金属离子的淋滤迁移,相反会对其产生沉淀和吸附,因此,可以考虑将该尾矿作为AMD处理的有用材料进行废物利用.     

高原深水型湖库水体重金属及营养盐耦合关系探究——以乌江构皮滩水库为例

水体富营养化及重金属污染都是严峻的水污染问题,二者可能存在一定的拮抗作用,但关于重金属与营养盐间耦合机理研究相对较少。本文选取乌江高磷背景的构皮滩水库为研究对象,分析2018年1、4、7、10月的支流表层水、库区分层水和下泄水的营养盐、溶解态重金属及相关水化学参数。通过不同组分间的Pearson相关分析及重金属聚类分析,发现As、Ni、Co与Mn可能主要来自于矿山废水,而Zn、Pb、Cd、Cr主要与生活、农业废水排放有关。Fe、DSi可作为指示重金属与营养盐耦合机制的代表元素,Fe用于表征外源及氧化还原条件的贡献,DSi可指示生物作用(包括吸收、分解等)的参与程度。结合DSi/TDN、As/Fe、Zn/As分析,表明该地区重金属及营养盐间的耦合关系主要受径流、硫酸盐还原作用及颗粒态污染物吸附/解吸等综合作用的影响。该研究为重金属及营养盐耦合机制探究提供一定的理论依据,同时对喀斯特深水型湖库复合污染治理具有重要指导意义。     

复垦铅锌矿尾砂库的植被恢复和基质演变

为探讨铅锌矿尾砂库经植物原位修复的生态恢复效果,以广西阳朔铅锌矿尾砂库综合治理示范工程为研究对象,连续3年(2018—2020)对实地观测植被恢复情况、新增植物生长情况及复垦铅锌矿库区尾砂重金属含量、土壤酶活性及理化性质的观测与测定。结果表明:尾砂库经人工种植的芒(Miscanthus sinensis)和三裂叶葛藤(Pueraria phaseoloides)2种耐性植物对尾砂中重金属存在植物稳定作用;库区植被新增物种逐年升高,且以豆科和菊科植物为主;尾砂的过氧化氢酶、脲酶与磷酸酶活性先增后减,蔗糖酶活性显著性增加;尾砂的肥力和保肥能力均有所提高,其中尾砂的总氮含量从1.14 g/kg增加到2.19 g/kg,有机碳含量从9.50 g/kg增加到21.01 g/kg。由此表明,在相似自然条件的矿山废弃地生态修复中,可考虑从葛属和蒿属的植物中筛选目标植物;植被恢复会加快尾砂库库区植物群落的次生演替;铅锌矿尾砂库经人工植被恢复能加快尾砂基质的演变,使生态系统实现自行恢复并达到良性循环。     

Reducing mine water requirements

Mining is a water intensive activity, and reducing water consumption is a key requirement in moving toward a more sustainable mining industry. This paper identifies mine water reduction, reuse and recycle options, and demonstrates cases where these options have been implemented around the world. A mine water system model is developed and used to show potential water saving strategies through six scenarios. Apart from the base case, these scenarios include the introduction of evaporation reduction strategies, paste tailings disposal, filtered tailings disposal, ore pre-sorting and a combination of the most effective options. The results of the modeling show how an open-pit copper mine with a traditional layout can move from having an average water withdrawal of 0.76 m³/t of ore processed to 0.20 m³/t of ore processed or lower. A key result of the modeling is the discovery that a combination of ore pre-concentration and filtered tailings disposal can reduce water consumption by 74% or more. This finding demonstrates an opportunity to significantly lower water consumption on mine sites.     

铜矿尾矿库修复植物香根草及其根际尾矿砂中重金属形态研究

香根草是一种能在极端环境中生长的草本植物。对安徽铜陵冬瓜山铜矿水木冲尾矿库生态修复植物香根草及其根际尾矿砂中重金属Cu、Zn、Mo和Cd进行了赋存形态分析。香根草根际尾矿砂中四种元素形态绝大部分是残渣态,但Cu和Cd的有效态含量远高于香根草正常生长所需,是主要胁迫元素。香根草的生物富集系数(BCF)和转运系数(TF)均小于1,表明它严格限制这四种重金属元素在根-茎叶中的迁移。乙醇提取态和去离子水提取态是植物体中活性较高的重金属形态。香根草地下部分Cu、Zn、Mo和Cd的乙醇提取态和去离子水提取态之和占各形态总和的比例分别为10%、23%、51%和16%;地上部分相应的比例为24%、26%、47%和12%。不同重金属元素表现出不同形态分布特征,这与香根草对它们的吸收和转运方式有关。香根草根际尾矿砂及其体内重金属形态决定了它对重金属的耐受性,表明香根草是有色金属矿山尾矿库理想的生态修复植物。     

Changes in the sorption, desorption, distribution, and availability of copper, induced by application of sewage sludge on Chilean soils contaminated by mine tailings

The effect of mine tailings and sewage sludge was evaluated on sorption, desorption, availability and distribution of copper in two soils, one high (sandy soil) and one low in copper (clay soil). In both soils contaminated by mine tailings the copper sorption capacity and the affinity of the substrate for the metal decreased substantially compared to the uncontaminated soils, however, the sorption remained always high in the clay soil substrates. In the substrates with sandy soil, the high Cu content and lower clay content were determining factors in the lower magnitude of the sorption. Similarly, metal desorption was closely related to these two parameters, and it was higher in clay soil with lower pH. In general, the application of sewage sludge favored the sorption of Cu in soils contaminated and uncontaminated with mine tailings, and in all cases desorption decreased, an effect that remained for at least 30 days. Simple extraction of Cu with CaCl2 and diethylenetriaminepentaacetic acid gave contradictory results, so a careful choice of the procedure is required, depending on the level of metal in the soil and on the acting principle of the extracting agent. In that relation, more complete information on the changes in the metal forms was obtained by application of the sequential extraction procedure proposed by the European Community Bureau of Reference.     

广西刁江沿岸土壤As,Pb和Zn污染的分布规律差异

分析了刁江流域矿区尾砂和上、中、下游地区土壤剖面重金属的含量. 结果表明:刁江流域上、中、下游地区都不同程度受到As,Pb和Zn的污染. 上游(距污染源16 km)表层土壤中w(As),w(Pb)和w(Zn)与尾砂相当,分别高达2.4×104,5.6×103 和1.2×104 mg/kg,下游拉烈和百旺(分别距污染源154和192 km)2个采样点表层土壤中w(As),w(Pb)和w(Zn)的平均值分别是《土壤环境质量标准》(GB15618—1995)三级标准的47.05,1.81和5.48倍. 表层土壤中w(As)和w(Pb)随采样点距污染源的距离增加呈幂函数下降,w(Zn)呈线性下降,表明Zn在流域内的迁移能力大于Pb和As. 土壤剖面中3种重金属的质量分数均随土层深度的增加呈降低趋势,在土壤剖面的迁移能力表现为Zn>Pb>As. 总体上看,刁江流域土壤污染与尾砂中重金属的形态及其迁移特征密切相关,尾砂的排放控制和治理应该是刁江流域污染整治的关键.      

北京市密云水库上游金铁矿区土壤重金属污染特征及对比研究

不同金属矿山选冶活动造成的矿区及周边土壤中重金属的分布累积特征不同.为了解密云水库上游金矿和铁矿矿区土壤中重金属地球化学特征的异同及污染状况,对区域内典型的金矿和铁矿矿区进行土壤样品采集,应用地球化学方法研究了2种土壤中重金属的污染特征,并应用地累积指数法评价了其污染状况.结果表明,2种土壤中除As外的其它重金属含量明显高于北京市土壤重金属背景值,金矿矿区土壤重金属含量普遍高于铁矿矿区.相关性分析表明,金矿矿区土壤中Cu含量与Pb、Zn(p<0.01)及Cr、有机质(OM)含量(p<0.05)之间显著相关,pH值与Pb含量(p<0.01)及Hg含量(p<0.05)呈显著负相关,而铁矿矿区土壤中重金属含量之间的相关性不显著.金矿尾砂中重金属含量明显高于铁矿尾砂,与矿区土壤污染状况一致.地累积指数法评价结果显示,金铁矿区土壤中重金属的污染程度均已十分严重,金矿矿区土壤污染程度高于铁矿,金矿矿区土壤重金属的污染程度由高到低依次为:Pb>Hg>Cd>Cr>Cu>Zn>Co>As;铁矿矿区土壤重金属的污染程度由高到低依次为:Pb>Cd>Cr>Co>Cu>Zn>Hg>As.该研究数据可为同一区域内不同金属矿区重金属污染的有效监控与治理提供科学依据.     

Life cycle assessment of mine tailings management in Canada

The effective management of mine tailings involves the control of several environmental impacts and legal requirements. Six tailings site management and closure scenarios were developed for a copper zinc underground mine located in Quebec (Canada) and compared using life cycle assessment (LCA). Two options are considered for the mine operation: tailings can be sent to the tailings disposal area where they are submerged or they can be partly used for backfilling. For each of these two operation options, three alternatives are presented for mine closure: (a) submerged tailings, (b) partial desulphurization with a cover of desulphurized material and (c) a cover with capillary barrier effects (CCBE) made of natural soils followed by revegetation. The goals of the study were to draw the inventory of these management scenarios from the development to the post-closure phase, to assess and compare their environmental impacts and to determine the importance of the land-use impact category. The potential impacts for each scenario were evaluated using the IMPACT 2002+ LCIA method. The results of the performed LCA indicate that for mine development and operation, scenarios where tailings are partly used as backfill for underground stopes appear to lead to larger impacts in 11 of the 14 midpoint categories since the backfill plant operation consumes a greater amount of material and energy. For a site closure period of 2 years, the CCBE option creates the greatest impacts, since it requires much more effort than the other techniques. The results for the post-closure phase have been analysed separately since they have a larger uncertainty. They appear to modify the comparative assessment results. The various results presented in the paper show the importance of taking land-use impacts into account.     

重金属对硫酸盐还原菌影响

含重金属硫酸盐废水是我国工业水污染的突出问题,利用硫酸盐还原菌的生物去除重金属的方法具有投资少、成本低、能耗少、去除率高,没有二次污染等优点而成为研究的热点。文章以混合培混养物作为接种污泥,考察不同浓度的重金属离子(Cu2+、Cd2+、Ni2+、Hg2+)对硫酸盐还原菌(Sulfate reducing bacteria,SRB)的抑制作用。研究表明:10 mg/L的Cu2+、Cd2+和20 mg/L的Hg2+对SRB还原硫酸盐的影响较小,硫酸盐最大去除率可分别达到94.1%、94.6%、91.3%,与空白(93.9%)相近;20 mg/L的Cu2+对SRB的抑制最为强烈,硫酸盐最大还原率仅为48.2%,剩余金属离子(Cd2+、Ni2+、Hg2+)都分别随着浓度的增大而对SRB的抑制作用增强;相同浓度的重金属离子对SRB的抑制顺序为Ni2+>Cu2+>Cd2+>Hg2+,抑制浓度分别为10、20、30、60 mg/L。最后阐述了各个反应器中硫酸盐还原率最大时,(WCOD/WSO42-)与硫酸盐还原率的关系。     

Compatibility of slurry wall backfill soils with acid mine drainage

The use of slurry walls to contain oxidized tailings and provide cutoff below tailings dams is generally a cost-effective way of preventing environmental degradation due to seepage of acid water from tailings areas. Long-term environmental protection dictates that the slurry wall materials be compatible with the acid water. Six percent Avonseal bentonite by weight was added separately to two natural soils to represent slurry wall backfill materials, which were then permeated with several pore volumes of acid mine drainage (AMD) in the laboratory. Results using both flexible wall and fixed wall permeameters were similar. The carbonate-rich backfill gave an average hydraulic conductivity (K) of 1×10⁻⁹ cm/s, buffered the AMD at circumneutral pH, and kept effluent metal concentrations to very low values (for example, less than 0.05 mg/l zinc). Although the carbonate-free backfill also maintained low K (average 3×10⁻⁸ cm/s) during AMD permeation, it could not neutralize the AMD as effluent pH decreased to approximately 3.5, and metal concentrations reached those of the influent or permeant after approximately 17 pore volumes.     

污泥屏障氧化缓冲容量与重金属再溶出关系研究

借助微生物厌氧活动特别是硫酸盐还原反应,污泥屏障可用来固定尾矿堆场重金属.针对尾矿风化淋滤形成的酸性采矿废水(AMD)与污泥之间发生的氧化还原反应导致的重金属溶出问题,通过氧化滴定实验研究了不同污泥悬液的氧化缓冲容量及其与重金属浓度的关系.结果表明,污泥悬液的氧化缓冲容量随着悬液固液比的增大略有减小,但随着悬液厌氧培养时间的延长而增加.污泥的氧化缓冲容量主要来自Eh≤-150mV的强烈还原区间,可达氧化缓冲容量的50%以上.氧化滴定过程中发现,当Eh≥-150mV时,Zn首先明显溶出;当Eh≥150mV时,Cu和Pb明显溶出.基于实验结果,建立了污泥屏障在AMD渗流条件下氧化缓冲容量消耗的数学模型.模拟计算结果表明,当AMD水头高度为10m时,厚度2m的污泥屏障经历AMD溶液38787a的渗透氧化,仍可保持原有的强烈还原状态,具备对重金属的固定效果.     

大厂矿区锡矿尾砂对银合欢生长的影响研究

大厂矿区锡矿尾砂含有多种有毒有害物质 ,尤其是重金属As、Cd、Zn ,严重限制了植物的自然定居与生长。筛选能适应如此恶劣的条件的植物种类和对尾砂进行适当的改良是锡矿尾砂库植被恢复与重建成功与否的关键。在温室内进行的银合欢栽培实验表明 ,城市垃圾肥能较好地改善尾砂的理化性质 ,可以起到替代土壤的作用 ;银合欢在尾砂含量和垃圾肥含量各为 50 %并添加适当磷肥的组合中生长良好 ,可以作为大厂矿区锡矿尾砂库植被恢复与重建的优选植物。     

模拟研究尾矿对环境的污染及治理探讨

文章通过对广东粤北地区几类典型的尾矿、废石等矿山废弃物进行酸雨淋洗的模拟实验,研究了酸性条件下矿山废弃物中重金属离子Fe、Ni、Pb、Zn、Mn、Cu和Cd以及硫酸根的溶出情况。结果表明,在酸雨条件下矿山废渣可以产生一定量的可溶性重金属,主要以Fe、Mn和Pb为主;尾砂同时产生一定的可溶性硫酸根,导致矿山流出水呈酸性。探讨了用石灰作为矿山流出水的pH调节剂、利用共沉淀除去重金属的可能性;并提出了治理尾砂堆场的措施。