The Key Factor of Acid Mine Drainage (AMD) in the History of the Contribution of Mining Industry to the Prosperity of the United States and South Africa: A Review

Mining industry has significantly contributed to the prosperity of the nation with economic growth, whereas mining operation has caused Acid Mine Drainage (AMD) with the abandonment of mines. As some researchers suggest, the history of AMD is, generally, affected by the change in not only mining industry but also in social and economic conditions. Thus, historical analysis is an effective way to find the key factors of AMD. In this study, in order to find the key factors of AMD, we examine the history of the United States (U.S.) and South Africa, where their economy had been developed owing to the large-scale mining, based on the findings in the previous studies. The results indicated that the abandoned mines due to the economic depression triggered AMD in the U.S. and South Africa. While the U.S. had progressively adopted anti-AMD methods in terms of prevention, prediction, and remediation (PPR) as a comprehensive approach, especially since the 1970s onwards because of the rise of environmental consciousness as well as strict regulations, South Africa is at the early stage of implementing the regulations following PPR. The public attention should be directed to environmental conservation in addition to the implementation of the regulations in South Africa. The improvement in socio-economic conditions is, additionally, necessary for the rise of environmental consciousness in South Africa in the light of the three pillars of sustainable development: social, economic, and environmental elements.

养殖废水对AMD重金属的处理效果及去除机制

文章研究牛粪发酵前后产物与酸性矿山废水(acid mine drainage,AMD)共处理过程及处理效果。结果表明,牛粪及发酵后产物(沼液)均对AMD具有不同程度的处理效果;处理前期,牛粪组R1和沼液组R2的pH值从3.07分别迅速升高到4.01和3.85,直至实验结束时pH值略有下降,分别达到3.91和3.47;酸度分别下降49.8%和44.83%。R1组Fe、Zn、Cu、Mn、Al等金属离子质量浓度分别下降72.34%、83.79%、96.48%、17.2%、46.89%;R2组Fe、Cu、Mn、Al质量浓度分别下降96.27%、61.40%、13.92%、48.19%。X射线衍射(X-ray diffraction,XRD)扫描结果表明2组实验对金属的去除主要以共沉淀为主,但在R1组中发现微生物可能对处理过程具有较大的推动作用。2组实验均对AMD具有较好修复效果,在利用养殖废水处理AMD具有很好的应用前景。

Acidophilic bacterial community reflecting pollution level of sulphide mine impacted by acid mine drainage

To reveal the impact of mining on bacterial ecology around mining area,bacterial community and geochemical characteristics about Dabaoshan Mine(Guangdong Province,China)were studied.By amplified ribosomal DNA restriction analysis and phylogenetic analysis,it is found that mining pollution greatly impacts the bacterial ecology and makes the habitat type of polluted environments close to acid mine drainage(AMD)ecology.The polluted environment is acidified so greatly that neutrophil and alkaliphilic microbes are massively dead and decomposed.It provided organic matters that can make Acidiphilium sp.rapidly grow and become the most bacterial species in this niche.Furthermore,Acidithiobacillus ferrooxidans and Leptospirillum sp.are also present in this niche.The amount of Leptospirillum sp.is far more than that of Acidithiobacillus ferrooxidans,which indicates that the concentration of toxic ions is very high.The conclusions of biogeochemical analysis and microbiological monitor are identical. Moreover,because the growth of Acidithiobacillus ferrooxidans and Leptospirillum sp.depends on ferrous iron or inorganic redox sulfur compounds which can be supplied by continual AMD,their presence indicates that AMD still flows into the site.And the area is closer to the outfalls of AMD,their biomasses would be more.So the distinction of their biomasses among different areas can help us to find the effluent route of AMD.

Diversity of microbial community at acid mine drainages from Dachang metals-rich mine, China

Two acid mine drainage(AMD)samples TS and WK,which were from the Dachang metals-rich mine in Guangxi province,China,were studied using PCR-based cloning approach.A total of 44 operational taxonomic units(OTUs)were obtained from the two AMD samples.However,only three OTUs(GXDC-9,GXDC-19 and GXDC-50)detected in sample TS can also be observed in sample WK.Phylogenetic analysis revealed that the bacteria in the two samples fell into four putative divisions,which were Nitrospira,Alphaproteobacteria,Gamaproteobacteria,and Acidobacteria.Organisms of genuses Acidithiobacillus and Leptospirillum,which were in gamaproteobacteria class and Nitrospira family,were dominant in two samples,respectively.In sample TS,which was characterized by low pH,high sulfate,high iron,and high arsenide,two species(Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans)constituted 98.22% of the entire microbial community.Compared with sample TS,the microbial community in sample WK was more diversified according to the observation.Interestedly,the Legionella species,which was rarely observed in the low-pH environment,was detected in sample WK.This work helps us to further understand the diversity of microbial community living in extreme acid mine drainages with unique geochemistry and the tolerance capability of acidophiles to heavy metal.

Microbial Community with Potential for Metal Release Isolated from Palca Mine Tailings Pond in Peru

The improvement of microbial characterization has increased the comprehension of microbial population and their ability in the microbiological metal dissolution. Bioleaching processes have been expanded to use microorganisms for the recovery of metals from ores and wastes. This study introduces Palca mine tailings pond in Peru which turned into acid mine drainage (AMD). AMD is a source of microbial communities whose microorganisms may support the aqueous extractive metallurgy for metal recovery. Four samples of AMD were collected from different locations and the elemental characterization showed concentrations of metals, such as Cu, Zn, Al, Mn, and Fe. The pH of the samples showed variation between 1.9 - 6.8. Twenty-one microorganisms were isolated and selected according the cell morphology. 16s rRNA gene sequences identified five species of which three belong to the bacterial kingdom and two to the Fungi kingdom. Two of the bacterial species were ferrous ion oxidizing bacteria, identified as Acidithiobacillus ferriphilus and Acidithiobacillus ferridurans;and the other one a ferric ion reducing bacteria identified as Acidiphilium acidophilum. The fungi species identified were Rhodotorula sinensis and Exophiala xenobiotica, a filamentous fungus isolated for the first time from an AMD.

Construction of Dry Cover System for Prevention of Acid Mine Drainage at Mine Waste Dump in Open Cast Coal Mines, Indonesia

Acid Mine Drainage (AMD) which occurs when sulfide minerals are exposed to water and oxygen with an excavation is one of the serious environmental problems in the world. A dry cover system is generally constructed in waste dump for the prevention of AMD in Indonesia by virtue of low cost and availability of waste rocks for a cover layer. However, the failure of the system caused by the lack of information related to the construction of cover system in mines, which leads to AMD, has been reported recently in Indonesia. In this study, the field investigation was conducted in pit and waste dump in open cast coal mine in Indonesia with the aim of obtaining the information on the construction of a cover layer and backfilling conditions of waste rocks in the waste dump. The rock samples taken in two areas of the mine were analyzed by geochemical analysis and sequential extraction with acids. The results indicated that Net Acid Producing Potential (NAPP) of the rocks in the waste dump down to 100 cm depth in both areas was from 10 to 30 kg H2SO4/ton, suggesting that Potentially Acid Forming (PAF) was backfilled in a cover layer. The backfill of PAF was contrary to the concept of cover system, which caused the failure of constructing a cover layer. The cause of the failure was likely attributed to the shortage of cover rocks which are classified as Non Acid Forming (NAF) or the failure of proper placement of them by an operational problem in the areas. Moreover, the results of the extraction with acids suggested that the form of iron and sulfur has to be taken into account to discuss the occurrence of AMD.

酸性矿山废水(AMD)中和渣对As吸附机制研究

利用中和渣富含铁次生矿物的特性,探究其作为吸附材料对废水中As的处理效果及机制,对中和渣的资源化处理处置具有重要的实际指导意义。以石灰乳一段中和渣(一段渣)、二段中和渣(二段渣)、石灰中和渣(石灰渣)和石灰石中和渣(石灰石渣)4种废弃物为吸附材料,采用吸附实验辅以ICP、XRD、FTIR等光谱表征技术研究其对As(Ⅲ)和As(Ⅴ)的吸附特性及机制以期实现以废治污。研究结果表明,4种中和渣对As(Ⅴ)的吸附效果优于As(Ⅲ),石灰石渣对As(Ⅲ)和As(Ⅴ)的拟合最大吸附量高于其他3种中和渣,分别为3.859 mg/g和4.988 mg/g。4种中和渣对As(Ⅲ)的吸附更符合准二级动力学和Freundlich模型,石灰石和石灰渣对As(Ⅴ)的吸附更符合Langmuir模型,吸附过程主要受化学吸附影响。中和渣对As(Ⅲ)和As(Ⅴ)的主要吸附机制为As(Ⅲ)和As(Ⅴ)与铁(氢)氧化物表面羟基官能团的表面络合和配位作用及铁矿物相转变过程中的络合和共沉淀作用。此外,石灰石、石灰和一段渣中As(Ⅲ)和As(Ⅴ)与铁结合形成新的含砷铁羟基硫酸矿物也是As固定的重要机制。

喀斯特地区煤矿酸性废水(AMD)综合治理研究

贵州重安江流域皮陇河源头区采矿形成的煤矿酸性废水(AMD)对地表及地下水造成严重污染。由于地处碳酸盐岩发育区,岩溶作用极其发育大大增加了AMD治理难度。基于喀斯特地区煤矿AMD治理项目实践,根据AMD产生和污染机理,结合区内地质环境条件和先进生态修复理念,采用生态修复综合技术对区内一系列生态环境问题进行系统治理:源头区采用“主动治理”技术,使用生石灰对AMD进行中和,对煤矸石等尾矿进行无害化封存填埋的同时修复相对隔水层杜绝源头AMD产生;末端采用“被动治理”技术综合应用,使用石灰石修筑可渗透反应墙、沉淀反应池、可渗透反应岸和生态湿地等工程,对AMD系统收集、逐级净化;同时在人工湿地中利用微生物、植物和水生动物联合作用对水体重金属离子逐级去除并恢复水生生态系统功能。治理后水体pH值由2.54~3.90提升至7.10~8.19,多呈弱碱性,Fe离子浓度由137.51mg/L下降至0.24mg/L,净化率达97.76%,重金属离子Hg、Zn、As等均得到净化。目前治理工程运行稳定且寿命随时间推移而延长,这一实践经验对喀斯特地区煤矿AMD治理具有重要推广应用价值。

碳酸盐岩处理AMD生成的污泥除磷初步研究

选取碳酸盐岩处理矿山酸性废水的污泥作为水中磷的去除材料,研究pH、温度、污泥投加量和接触时间对磷去除作用的影响,以及在此过程污泥中重金属的释放情况。试验表明:当水中磷浓度为10 mg/L,温度25℃,接触时间10 min,污泥投加量0.5 g,pH为7时,磷的去除率达到99.9%以上。实验中污泥有少量重金属的释放,但仍满足相关排放要求。结果表明碳酸盐岩处理矿山酸性废水的污泥对磷有很好的去除效果,在实现废弃物二次利用的同时,对环境不造成影响,是一种很好的污水中磷去除材料。

AMD蚀化下砂岩的损伤本构模型

通过酸性矿山排泄水(AMD)蚀化砂岩的力学性质研究,利用Weibull函数分析砂岩微元体强度分布特征,导出单轴压缩下砂岩的损伤本构关系;基于AMD蚀化下砂岩主要胶结物含量的变化,引入砂岩化学损伤变量,得到蚀化后砂岩的等效弹性模量;根据推广的Lemaitre应变等效原理,建立AMD蚀化下砂岩的损伤本构模型。利用现场采集的pH为1.07和3.26的AMD溶液蚀化下砂岩单轴抗压试验,以及文献[7]中人工配制pH为3.0和5.0酸液溶蚀砂岩试验结果,分别检验所建本构模型的合理性。结果表明:模型预测曲线与试验结果曲线基本吻合,较客观地反映AMD蚀化下砂岩的损伤演化特性。

碳酸盐岩处理AMD生成的污泥去除Sb(V)性能研究

以碳酸盐岩处理酸性矿山废水产生的污泥为吸附剂,研究吸附时间、初始浓度、pH、离子强度对水中Sb(V)吸附性能的影响。结果表明,在pH=6.0条件下,Sb(V)在AMD污泥上的吸附平衡时间为22 h,准一级、准二级动力学方程对其均有较好拟合性;Langmuir和Freundlich吸附等温模型均适合对吸附过程进行拟合,Langmuir模型能更好地反映吸附特性,其最大吸附量为8.39 mg/g。在强酸环境下,AMD污泥对Sb(V)的吸附量明显增大。离子强度对Sb(V)在AMD上的吸附影响较小。实验过程中会溶解出一部分重金属,但仍符合排放要求。AMD污泥对Sb(V)表现出明显的吸附效应,在工程意义上实现了废物二次利用。

改性粉煤灰净化酸性矿山废水污染机理研究

煤矸石堆存过程中产生的酸性矿山废水(acid mine drainage,AMD)对周边水环境具有严重污染风险。基于“以废治废”理念,选择煤炭燃烧产生的粉煤灰开展了去除AMD中污染物的研究。针对粉煤灰原灰处理效果不佳的现状,对比了不同改性条件下的粉煤灰对AMD中污染物的去除效果,筛选出了去除效果最佳的粉煤灰改性材料,并从微观层面解析了粉煤灰改性材料去除污染物过程中的作用机理。结果显示:经Ca(OH)_(2)助熔焙烧改性粉煤灰处理后,模拟AMD废水中的Fe、Mn含量由100mg/L降至低于1 mg/L,污染物去除率达99%。Ca(OH)_(2)助熔焙烧改性粉煤灰对Fe、Mn的吸附过程主要为单层化学吸附,在0~2 h内吸附接近平衡。此外,Ca(OH)_(2)助熔焙烧改性增加了粉煤灰表面粗糙度和孔隙数量,并在表面形成六面体晶相结构。同时,Ca(OH)_(2)助熔焙烧改性过程活化了粉煤灰颗粒表面Si和Al元素,提高了其Zeta电位,减少了游离羟基,增加了固定羟基,从而增强了其对污染物的吸附能力。Ca(OH)_(2)助熔焙烧改性显著提高了粉煤灰对AMD中污染物的去除率,为粉煤灰治理AMD提供了材料与方法依据。

石灰石耦合AMD内源铁氧化物去除重金属的机制

该文通过添加石灰石中和分别来源铜矿和煤矿的3种酸性矿山废水(AMD),研究石灰石耦合AMD-Ⅰ(铜矿)、AMD-Ⅱ(煤矿)和AMD-Ⅲ(煤矿)中内源Fe对Cu、As、Zn的去除效果。选取富含Fe^(2+)和Fe^(2+)的同一地区废水(AMD-Ⅱ和AMD-Ⅲ),设计温度、时间和温度+时间因素,阐明时间条件对不同Fe^(2+)/Fe^(2+)AMD沉积物中铁氧化物形貌与晶型的变化,同时用高温加速反应进程,推演石灰石耦合内源铁氧化物对Cu、As、Zn去除的稳定化机制。结果表明,室温条件下,石灰石处理后3种AMD中Cu和As随着Fe的沉降同步去除,在2 h时去除率已经达到94.53%~99.99%,而Zn的去除均相对滞后,2 h的去除率仅为5.06%、54.09%和26.71%,说明Zn的去除方式受来源、水质特性影响较大。随着时间的增加(90 d),AMD-Ⅲ(Fe^(2+)含量85.24%)产生的沉积物中铁氧化物由最初的水铁矿向纤铁矿转变,AMD-Ⅰ中铁氧化物向纤铁矿和针铁矿转变,而AMD-Ⅱ(Fe^(2+)含量47.75%)中在整个培养期内仍为最初的水铁矿。因此,AMD的初始pH、内源Fe^(2+)/Fe^(2+)的比例是决定石灰石处理后沉积物中铁氧化物的组成与形貌的主要因素。随着温度、时间或温度+时间的增加,在AMD-Ⅲ(Fe^(2+)含量85.24%)的最终沉积物中铁氧化物主要表现为针铁矿和磁铁矿,AMD-Ⅱ(Fe^(2+)含量21.62%)主要为赤铁矿。而且,整体变化过程中供试的AMD-Ⅱ和AMD-Ⅲ中Cu、As、Zn均没有重新释放至液相,且其变化规律与室温一致。研究结果对正确处理和处置石灰石中和AMD后产生的沉积物有一定的指导意义。

纳米磁性颗粒增强酸性矿山废水污泥沉降性能研究

针对宜昌市某废弃煤矿山酸性矿山废水(AMD)污泥沉降效率低下的问题,采用溶剂热法成功合成纳米磁性颗粒(MNPs),并系统研究MNPs与阴离子聚丙烯酰胺(APAM)絮凝剂联合作用对AMD污泥沉降性能的增强机制。实验结果表明,在MNPs与APAM最佳用量(分别为0.2和1 g/L)条件下,APAM显著缩短污泥沉降的时间,沉降速率从1.6 cm/min提升至2.5 cm/min,增幅高达56.3%,有效地提升了处理效率。同时,MNPs的协同作用进一步增强污泥的压缩与脱水能力,临界点体积比(V_(f)/V_(m))_(cp)从0.27降低至0.19,有效地降低了处理成本。通过光学显微镜观察发现,MNPs在絮凝体中的分布可增强颗粒间相互作用,促进高效沉降与体积压缩。MNPs与APAM联合处理后的出水水质显著改善,各项指标均趋近于或达到国家相关排放标准,体现了该技术在环境修复中的有效性。此外,磁絮体再生实验显示,MNPs回收率近90%,且多次循环使用后其沉降效能保持稳定,验证了该技术的经济性与可持续性。

Kinetics of Neutralization of Polymetallic Mining Discharges from the Perkoa Zinc Deposit in Central-Western Burkina Faso

Oxidized and acidic mining discharges(pH between 4 and 5)from the Perkoa zinc mine in Burkina Faso consisting of waste rock,crusher rejects and mining tailings were sampled and used for neutralization tests with calcareous dolomite(for six months).The mining discharges and the calcareous dolomite were previously characterized.Columns of 60 cm length and 15 cm diameter were used for the tests.Then,2.62 kg of calcareous dolomite was deposited on the mining discharges in each column.Two liters of deionized water are added every 15 days to each column.Samples were taken at the outlet of the columns at time intervals and then analyzed to assess the evolution of pH,electrical conductivity and contents of PHEs(Potentially Harmful Elements)over time.Following the neutralization tests on solid mining discharges,neutralization tests were also carried out on acid leachates resulting from the oxidation of these same solid mining discharges with calcareous dolomite.The results show that calcareous dolomite is very effective for the neutralization of SR(Sterile Discharges)and the precipitation of PHEs contained therein.It is also effective in buffering acidic effluents from these sterile discharges.As for other mining discharges(crusher rejects and mining residues),although calcareous dolomite is not effective in neutralizing these oxidized and acidic solid discharges,it is however effective in precipitating PHEs such as arsenic and lead.Calcareous dolomite is also effective in buffering acid leachates from these oxidized and acidic mining discharges(crusher rejects and mining tailings).

两种天然矿物对高砷煤矿区AMD污染水体底质污染物释放的影响

为探索利用天然矿物进行高砷煤矿区AMD污染水体底质污染释放的原位控制,以高砷煤矿区AMD污染湖泊底质为研究对象,添加不同比例的碳酸钙和磷矿粉后,分别对AMD污染底质进行7 d的连续浸提试验,并测定浸提液中p H、Eh、EC、SO2-4、Mn、Zn、Cu、As等特征指标浓度,评价2种天然矿物组分对AMD污染底质的污染释放控制效果。结果表明:碳酸钙、磷矿粉的添加可显著地提高污染底质的p H,并显著降低污染底质的氧化还原电位以及Mn、Cu、Zn离子的溶出,但浸提液EC和SO2-4却有不同程度的升高,且碳酸钙处理后浸提液EC和SO2-4的增幅显著低于磷矿粉处理;磷矿粉处理对底质中As离子的溶出有明显的抑制效果,而碳酸钙处理的效果则不明显,因此磷矿粉可作为高砷煤矿地区酸性废水污染湖库底质二次污染防治的理想材料。

共存阳离子对含锰酸性矿山废水化学中和处理过程的影响

文章采用化学中和法处理模拟酸性矿山废水(acidminedrainage,AMD),探究共存离子Fe^(2+)、Mg^(2+)和Al^(3+)在曝气搅拌和机械搅拌2种条件下对锰的去除率及其固相产物的影响.结果表明:3种共存离子对锰的去除均具有一定的促进作用;其中Al^(3+)的作用最显著,但Al^(3+)及其产物对锰离子的氧化有抑制作用;Al^(3+)、Fe^(2+)的存在会降低固相产物中锰元素的质量比并影响沉积物组成,不利于后续回收处理.研究结果可为化学中和除锰工艺优化及固相产物回收利用研究提供参考.

剩余污泥裂解灰陶粒吸附酸性矿山废水中Zn^(2+)、Cu^(2+)、Pb^(2+)性能及机理

以剩余污泥裂解灰为主要原材料,按照剩余污泥裂解灰∶膨润土∶淀粉为6∶3∶1的比例混合,经过造粒、熟化、干燥,最后于1050℃氮气气氛下煅烧60 min制备多孔陶瓷颗粒。采用SEM-EDS、XRD表征陶粒吸附酸性矿山废水中Zn^(2+)、Cu^(2+)、Pb^(2+)前后的微观形貌、元素变化及晶体结构。结果表明,所制备陶粒表面粗糙,具有大量孔隙结构。当陶粒投加量为3 g,初始pH=3.2,反应时间24 h时,制备的剩余污泥裂解灰陶粒对于Zn^(2+)、Cu^(2+)、Pb^(2+)去除率分别达到99.20%、85.10%、96.27%。初始pH为中性时陶粒吸附效果优于酸性条件。陶粒对于Cu^(2+)、Pb^(2+)的吸附过程符合准二级动力学模型,以离子交换为主;对于Zn^(2+),准一级与准二级动力学模型均能较好拟合,物理吸附与化学吸附发挥同等重要作用。陶粒吸附过程均符合Freundlich等温模型,对于Cu^(2+)的吸附主要发生在非均相活性位点,对于Zn^(2+)和Pb^(2+)的吸附既可以发生在均相单层也可以发生在非均相活性位点。利用剩余污泥裂解灰制备多孔陶瓷颗粒,不仅可以用于酸性矿山废水中处理重金属离子,还能解决污泥处置的问题,达到以废治污的目的。

川东华蓥山废弃矿井水化学特征及影响因素分析

对废弃煤矿酸性矿井水(AMD)、地表水、地下水的水化学特征及影响因素进行分析,可为保护华蓥山水环境提供理论支撑。以广安市华蓥山废弃煤矿群为研究对象,基于水化学参数统计,运用水化学、相关性分析和离子比等方法对水样进行了综合分析研究。结果表明:岩溶水化学类型大多为HCO_(3)-Ca型;非酸性矿井水主要为HCO_(3)-Ca型为主;酸性矿井水主要主要为SO_(4)-Ca和SO_(4)-Na;受酸性矿井水影响的地表水化学类型以SO_(4)-Ca和SO_(4)-Na型为主;酸性矿井水的形成演化除了受溶滤、浓缩、混合及阳离子交换作用外,主要受黄铁矿(FeS_(2))的氧化还原反应影响。研究该区废弃矿井水化学特征及控制因素,将为酸性矿井水治理方案提供理论基础,从而削减入江污染负荷,从“源头”上保护长江生态环境。