A Statistical Determination of the Transit Speed of Pollutants in a Water Reservoir Affected by Acid Mine Drainage from the Iberian Pyrite Belt

The El Sancho reservoir is located in the Odiel River basin, which crosses the Iberian Pyrite Belt. The reservoir receives acid mine drainage (AMD) from the Meca River, a tributary of the Odiel River. Two multi-parameter probes, one placed at the tail (up-gradient) end of the reservoir, where the contaminants enter, and another close to the reservoir dam were used to characterize acidity migration through the Sancho reservoir. The probes both measured pH and conductivity every 30 min. Two different levels of contamination were found, due to dilution that takes place within the reservoir and changes in the AMD composition. The cross-correlation function allowed quantification of the migration process from tail to dam. For both pH and conductivity, the maximum correlation occurred 17 days after sampling, indicating a mean transit time of 17 days. Since the distance between the two sampling points was 14,500 m, the contaminant transit speed was 0.0098 m/s.     

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.

     

Precious metals in gossanous waste rocks from the Iberian Pyrite Belt

The Iberian Pyrite Belt (IPB) is one of the largest (if not the largest) of the world’s massive sulphide provinces. Since the Chalcolithic era, gossans formed from the massive sulphide mineralisations have been worked for copper, silver and gold, and consequently many historic mine sites have abandoned dumps of gossanous material. The aims of this study are to determine the mineralogical hosts of precious metals (Au, Ag) and environmentally significant elements (As, Ba, Bi, Cu, Hg, Mo, Sb, Se, Pb, Zn) in gossanous waste rocks from historic dumps, using geochemical, optical, SEM–MLA and laser ablation techniques. Results demonstrate that the precious metals are contained as inclusions of electrum, Au and Ag–Hg halides commonly within iron oxides and hydroxides. At least part of the inclusion surfaces are exposed and thus may be amenable to processing, however, the encapsulated nature of the precious metal inclusions along with their small size could make mineral processing difficult. In addition, the As, Bi and Pb enrichment of iron oxides and the presence of Ag–Hg halides may require suitable and safe storage of processing wastes. The study indicates that a solid knowledge of the mineralogical siting of precious metals and environmentally significant elements in gossanous waste rocks is required to assess processability in the move towards sustainable mineral resource development.     

Physico-chemical gradients and meromictic stratification in Cueva de la Mora and other acidic pit lakes of the Iberian Pyrite Belt

A marked vertical trend of increasing temperature and dissolved metal concentrations is observed in the monimolimnia of some meromictic pit lakes of the Iberian Pyrite Belt (IPB) in SW Spain. Temperature differences between the chemocline and the pit lake bottom can be as high as 15°C (e.g. Herrerías), and the respective concentration of some metals (e.g. Fe) and metalloids (e.g. As) can increase by several orders of magnitude (e.g. Cueva de la Mora). The redox conditions also change drastically from the upper and oxygenated mixolimnion (strongly oxidizing) to the lower and anoxic monimolimnion (moderately reducing). Processes such as the inflow of metal–sulphate laden ground water from flooded shafts and galleries, and other factors such as the pit geometry or the relative depth of the lakes, must be considered to account for the observed stratification pattern. The vertical profiles of physico-chemical parameters and water chemistry obtained in Cueva de la Mora and other meromictic pit lakes of the IPB are also compatible with a reactive bottom in which several geochemical and microbial reactions (including reductive dissolution of Fe³⁺ minerals, bacterial reduction of Fe³⁺ and SO₄ ²⁻ in pore waters within the sediments, and decomposition of organic matter) could be taking place.     

Secondary Sulphate Minerals in a Cyprus-Type Ore Deposit,Apliki, Cyprus: Mineralogy and Its Implications Regarding the Chemistry of Pit Lake Waters

The Apliki mine, a Cyprus-type massive sulphide deposit in Cyprus, was exploited for copper until the mid-1970s. Abandonment of the mine left a deep pit that now hosts a lake fed by surface runoff from the surrounding mineralized zone and hydrothermally altered basalt. Oxidation of the sulphide minerals and factors such as climate and terrain relief control the water–rock interactions that generate acid mine drainage (AMD), which ultimately affects and defines the quality of the lake waters. Pyrite and chalcopyrite constitute an almost inexhaustible sulphide source that leads to the formation of a variety of secondary iron and copper mineral phases. The secondary mineral assemblages in the ore zone are mainly iron, copper, and magnesium sulphates, whereas the lakeshore assemblage is dominated by magnesium-, calcium-, sodium-, and aluminum-bearing sulphate minerals. Near the lakeshore, the highly soluble iron sulphate salts dissolve in the lake water, increasing its iron content. Other less soluble salts are more stable and persist in the lakeshore environment. The precipitation and dissolution of efflorescent salts, and, to a lesser extent, the oxidative weathering of the remaining ore minerals, produce additional AMD. Due to the perpetual cycle of mineral dissolution and precipitation, the lake has a low pH (≈3) and contains high concentrations of some contaminants. The processes that contribute to the formation of the efflorescent mineral assemblages and their environmental impact on pit lake waters, and indeed the complete geochemical system, is a typical example of secondary mineral formation in Cyprus-type Cu-pyrite massive sulphide ore deposits.     

A New Application of Solvent Extraction to Separate Copper from Extreme Acid Mine Drainage Producing Solutions for Electrochemical and Biological Recovery Processes

Over the last decade, AMD waters have gained more attention as a potential source of metals due to the emerging need to recover or recycle metals from secondary resources. Metals recovery supports sustainability and the development of a circular economy with benefits for resource conservation and the environment. In this study, five extractants (Acorga M5640, LIX 54, LIX 622, LIX 622 N, and LIX 864) diluted (15% (v/v)) in Shell GTL with 2.5% (v/v) octanol were compared and evaluated for Cu recovery from an extreme AMD sample (5.3?±?0.3 g/L Cu) collected at the inactive São Domingos Mine in the Iberian Pyrite Belt of Portugal. Of the five extractants, Acorga M5640 showed the best selective efficiency. Further tests showed that 30% (v/v) of this extractant was able to selectively extract ≈ 96.0% of the Cu from the AMD in one extraction step and all of the remaining Cu (to below detection) in three steps. Among the different stripping agents tested, 2 M sulfuric acid was the most efficient, with ≈ 99% of the Cu stripped, and the recyclability of the organic phase was confirmed in five successive cycles of extraction and stripping. Furthermore, contact time tests revealed that the extraction kinetics allows the transfer of ≈ 97% of the Cu in 15 min, and aqueous to organic phase ratios tests demonstrated a maximum loading capacity of ≈ 16 g/L Cu in the organic phase. Raising the concentration of Cu in the stripping solution (2 M sulfuric acid) to ≈ 46 g/L through successive striping steps showed the potential to recover elemental Cu using traditional electrowinning. Finally, a biological approach for Cu recovery from the stripping solution was evaluated by adding the supernatant of a sulfate-reducing bacteria culture to make different molar ratios of biogenic sulfide to copper; ratios over 1.75 resulted in precipitation of more than 95% of the Cu as covellite nanoparticles.

Graphical Abstract

     

Chemometrics in Ascertaining Hydrogeochemical Characteristics of Coal Mine Discharge vis-à-vis Behaviour of Surface and Groundwater Resources of the Mahan River Catchment Area,Central India

We investigated the hydrogeochemical regime of an AMD-affected coal mining province. 98 water samples were collected over two seasons and analysed for 14 parameters. We attempted to discriminate the sources of variation of water quality using select multivariate techniques: display methods (principal component analysis) and unsupervised pattern recognition (cluster analysis). Most of the groundwater and river water were characterised by shallow freshwater facies (Ca–Mg–HCO₃ type), whereas the samples representative of mine water were of the Ca–Mg–SO₄ type. The mines of the area annually discharge 2901 t of solute loads, ranging from 91 to 1030 t/year. Various molar ratios suggest that dissolution of the silicates associated with the mixing process is the predominant solute acquisition processes that govern the water chemistry of the region besides AMD. The chemometric results indicated that only a few groundwater and river water samples had low pH and elevated total dissolved solids, and these were near the three mines that were affected by AMD. These results substantiate the effectiveness of the mine water treatment measures implemented at the mine sites.

     

Phosphate coating on pyrite to prevent acid mine drainage

Abstract

Acid mine drainage (AMD) is a serious environmental problem that preoccupies the Canadian Mineral Industry. Considerable amounts of money are spent every year in an effort to prevent or reduce the acid mine drainage phenomenon. AMD occurs when sulfide minerals (ex. pyrite) contained in rock are exposed to air and water and subsequently oxidize to produce low pH water. This acid effluent has the potential to mobilize any heavy metals contained in the rock. Coating the sulfide minerals with iron phosphate is a new promising technology to reduce AMD.Pyrite is treated with a solution containing H₂O₂, KH₂PO₄ and sodium acetate (NaAc). H₂O₂ oxidizes a small part of pyrite producing ferric iron (Fe³⁺) anions. These cations subsequently react with the PO₄ ^3? anions to produce FePO₄ that precipitates on the pyrite surface producing a passive coating. This iron phosphate coating can protect the grains of pyrite from oxidation. This paper presents a series of experiments that confirm that iron phosphate coating can considerably reduce AMD.     

新桥矿业公司充填技术的演变与应用

介绍了新桥矿业公司充填采矿方法的变革,总结了多种充填技术在该矿的发展与应用,重点分析了废石不出坑充填技术和高浓度江沙料浆自流充填技术.本文对充填技术的推广,具有一定的参考价值.     

江砂胶结充填体抗压强度的多元回归研究

针对新桥硫铁矿胶结充填存在的质量问题,对该矿的江砂胶结充填体进行了室内单轴抗压强度正交试验。通过对试验结果进行多元回归分析,建立了江砂胶结充填体抗压强度与浓度、水泥含量、粒径、养护时间、温度等影响因素的回归关系式,得出影响充填体强度的最主要因素为粒径。研究结果为提高充填体质量和降低充填成本提供了依据。     

黄铁矿表面氧化机理及动力学影响因素研究进展

黄铁矿作为矿区环境中最为常见的金属硫化物尾矿，在表生环境下易被氧化形成酸性矿山废水（acid mine drainage，AMD），进而产生一系列环境污染问题。因此，黄铁矿表面氧化机理及其动力学影响 因素研究一直是矿区污染环境治理领域的研究热点。首先概述了黄铁矿基本结构和物理化学性质，指出黄铁矿表面氧化机理及其规律研究对于从源头上减缓酸性矿山废水（acid mine drainage，AMD）的产生、改善黄 铁矿光伏材料的应用缺陷、从黄铁矿结构中高效浸出伴生的贵重金属及完善地球上Fe、S循环都具有重要意义。然后，较为系统地从黄铁矿氧化形成AMD机理、微生物介导下的黄铁矿生物氧化机理、黄铁矿表面氧化机 理电化学研究、黄铁矿表面氧化过程中硫元素转化机理等4个方面综述了黄铁矿表面氧化机理。紧接着，分别概括了腐殖酸、无机酸根离子、常见氧化剂对黄铁矿化学、生物及表面电化学氧化对黄铁矿表面氧化动力学 的影响。最后，指出未来可借助一些原位微观界面研究手段，进一步加强微生物与黄铁矿的界面作用的微观机理研究，探究多因素耦合作用下黄铁矿表面氧化规律，建立一个预测自然环境下多因素耦合下黄铁矿氧化 速率模型。     

Thallium and Other Potentially Toxic Elements in the Baccatoio Stream Catchment (Northern Tuscany,Italy) Receiving Drainages from Abandoned Mines

Acid mine drainages (AMD) have adversely affected the southern Apuan Alps (northern Tuscany, Italy). The study particularly focuses on the Baccatoio stream, which receives AMD from the abandoned Pollone and M. Arsiccio mines. The mine waters have an average pH of 2.2 and contain potentially toxic elements (PTE) at concentrations that exceed the Italian regulatory threshold for Al, Fe, Mn, Cu, Zn, As, Ni, Co, Cd, Sb, Pb, and Tl. The AMD flow directly into the stream, severely contaminating it. Downstream of the mined areas, the pH increases and most PTE (especially Fe, Al, As, and Pb) are readily scavenged from the stream waters by precipitation and/or adsorption. However, Tl, which peak at 1000 µg/L in the AMD, behaves almost conservatively along the stream flow path, undergoing only dilution, and remains at or above the concentration of concern of 4 µg/L almost to the coastline, before sharply decreasing to 0.5 µg/L where seawater is encountered. Since the stream water was locally used for irrigation, these observations may have important environmental and public health consequences in such a densely populated area.     

充填尾砂浆体粘度测量的初步探讨

由于充填料浆属于非牛顿体,其粘度值受多种因素影响而变化,不可能像普通牛顿体那样采用管流法、落体法、圆盘法、振动法等进行简单量测.根据充填料浆特性,以新桥硫铁矿尾矿浆(质量浓度70%)为研究对象,进行了充填料浆粘度测定方法的探讨.结果表明,待测充填料浆充分搅拌后2 min内利用旋转粘度计测得的粘度值变化幅度小于±15%,...     

Geophysical Diagnosis of Diversion Channel Infiltration in a Uranium Waste Rock Pile

The Osamu Utsumi mine was the first to economically mine uranium ore in Brazil. During its operation, a river valley was buried for the construction of the waste rock pile. The original stream was diverted to the northwest side of the pile and has since flowed into a diversion channel devoid of basal waterproofing, while an acid mine drainage (AMD) source flows at the base of this waste rock pile. This research aims to evaluate the possible relationship between water infiltration of the diversion channel and the AMD resurgence at the base of the pile using electrical resistivity tomography and induced polarization. 2D inversion models and pseudo-3D maps allowed the recognition of low resistivity zones (<?100 Ω·m) with high chargeability areas (10 mV/V). Some of these low-resistivity areas have been interpreted as infiltration zones in segments of the diversion channel into the pile, and in one of them, the flow intercepts a high chargeability area interpreted as a sulfide-rich zone that is expected to contribute to AMD at the base of the pile. Understanding the hydrogeochemical process will help select effective actions to mitigate the generation of AMD at the mine, which is currently in the decommissioning phase.

     

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.

     

Tracking the prokaryotic diversity in acid mine drainage-contaminated environments: A review of molecular methods

The negative impact of acid mine drainage (AMD) on public and environmental health by degrading the aquatic and terrestrial ecosystem with a drastic decrease in pH and elevated levels of toxic heavy metals, metalloids and radionuclides necessitate the development of environmentally sustainable technologies to remediate AMD. The development of appropriate strategies for controlling and/or abating the detrimental effects of AMD in natural and mining environments primarily depends on the diversity and compositions of the local acidophilic microbial communities (those which can grow at pH ? 3) which catalyze the reactions of AMD by production of sulfuric acid and ferric iron. Robust method(s) to track the AMD-promoting microbial communities will not only provide information about their ecophysiological role in extreme environments but also help sustain the reliability of remediation technologies. This paper provides an overview on the phylogenetic diversity of prokaryotes present in AMD-impacted environments, and different molecular methods that have been used to track the diversity of these acidophiles. Additionally, the high-throughput methods (metagenomics, metaproteomics and microarrays) that link prokaryotic phylogeny to their function in AMD systems are also discussed.     

The Effects of Isolation and Acid Mine Drainage on Fish and Macroinvertebrate Communities of Monday Creek, Ohio, USA

Isolated headwater streams in mined watersheds may have good water quality and fish habitat, yet be disconnected from immigration sources by stream segments impaired by acid mine drainage (AMD). Studies of fish and macroinvertebrate communities, habitat, and a number of hydrochemical parameters in Monday Creek, Ohio, show that AMD eliminates fish communities and severely limits macroinvertebrate communities in directly affected tributaries. Isolated headwaters in the heavily mined Monday Creek watershed have relatively good water quality and habitat, but poor fish communities. Comparison of isolated Monday Creek headwaters with non-isolated reaches in unmined watersheds indicates that differences in fish communities are attributable to isolation. Fish communities in isolated headwaters have lower Indices of Biotic Integrity (IBI) than comparable non-isolated communities, reduced species numbers, and lower numbers of individuals, despite suitable habitat as measured by the Qualitative Habitat Evaluation Index (QHEI). Comparison of macroinvertebrate communities shows higher Invertebrate Community Indices (ICI), and no apparent species loss, which can be attributed to the obligate flight stage in the life cycle of many macroinvertebrates, which enables them to overcome aquatic barriers. The implication of this research is that there is an opportunity for recovery of depleted fish communities in large AMD-isolated areas with good water quality, suitable habitat, and intact macroinvertebrate communities, by downstream treatment or source control of AMD to create aquatic corridors for fish immigration.     

青岛市水源主要污染物调查评价及环境风险分析

从点污染源入河量研究了青岛市12处城镇生活和工业排污情况,对35座水库的面污染入河量进行了详细调查。通过点污染入河量分析,证明各区域污水处理厂污水排放量在合理范围内。经过面污染入河量统计分析,青岛市水库面污染1个主要的来源是分散式畜禽养殖污染物,其次为农村生活污染、农田肥料和农药流失污染物、城市地表径流污染物。另外,分析了水污染对环境风险的危害,并提出了治理措施和方案。     

阶段矿房法采空区围岩稳定性分析及处理方案

张家沟硫铁矿经过多年开采,在井下形成了大量采空区,给下部矿体的开采带来了很大安全隐患。在综合分析张家沟硫铁矿采空区存在现状及地质概况的基础上,提出了3种开采方案,采用FLAC^3D对+120 m水平的采空区稳定性进行数值模拟计算,分析了不同回采方案下矿柱及空区应力场的变化规律,通过对比分析,确定采场最优回采顺序,在此基础上,提出了采空区的处理方案,安全崩落顶盖,在113采场底柱上部形成足够厚度的松散垫层。研究结果可为现场的施工设计提供科学依据。     

影响深海多金属硫化物选冶的矿物学因素

某深海多金属硫化物中锌、铜、金、银的品位分别为20.44%、0.41%、6.89g/t和141g/t,有价元素含量高,综合利用价值大。通过矿物组成、重要矿物的嵌布特征、嵌布粒度及磨矿产品中解离特征的研究,对影响选冶回收的矿物学因素进行了系统的分析。研究表明:闪锌矿是含量最多的矿物,具有含铁量变化较大、铁含量普遍较低、嵌布粒度不均、与自然硫和黄铁矿密切共生的特点,通过选矿可以获得高品质的锌精矿。自然硫的粒度细、与闪锌矿和黄铁矿共生紧密,但其浮游性能好,对铜、锌的选别影响较大,可以考虑优先浮选自然硫,以减少其对后续分选的影响。金、银矿物主要为自然金、银金矿和辉银矿,嵌布粒度细,基本都在0.005mm以下,与黄铁矿、闪锌矿的共生关系密切,由于闪锌矿和黄铁矿含量高,难以直接通过浮选的方式获得高品位的金、银精矿。