Correction to: Corrosion of Metallic and Structural Elements Exposed to Acid Mine Drainage (AMD)

Mine Water and the Environment -     

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。     

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 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.     

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.     

酸性矿山废水的污染与治理技术研究

分析了酸性矿山废水的成分、危害、来源和排放特点,经试验研究,推荐以添加缓蚀剂中和为主的几种既又实用的酸性废水治理技术,以实现废水的循环利用和无害排放。     

A Geotechnical Solution to Reduce Acid Mine Drainage Generation at Recreio Mine

Coal mining is frequently associated with acid mine drainage (AMD) generated by tailings and waste dumps containing sulphide minerals. A practical and economical alternative to minimise AMD generation is to avoid the contact between water and waste dumps using a compacted soil cover. This study evaluates the use of distinct raw materials as cover layers. The study area was an open pit coal mine in the south of Brazil. Geotechnical characterization, physical, chemical and mineralogical analyses were carried out on two different soils from this mine. Hydraulic conductivity tests were performed using Flexible-Wall Permeameter. The results obtained from the hydraulic conductivity tests for two compacted soils suggest their applicability as impermeable layers. Considering the operational aspects at the mine and the characteristics determined for the soils a new construction scheme for the dump site was suggested.     

Partition of Rare Earth Elements Between Sulfate Salts Formed by the Evaporation of Acid Mine Drainage

Acid mine drainage (AMD) contains rare earth element (REE) concentrations several orders of magnitude higher than those of the rest of natural waters and could be a secondary source of REEs. In arid to semiarid climates with a long dry season, the precipitation of efflorescent sulfates constitutes a transient storage of REEs. The REE partition among the Al–Fe–Mg–Ca sulfates formed by the evaporation to dryness of six different AMDs was investigated by statistical methods and by selective dissolution. The chemical composition of the evaporitic salts showed that only three principal components (PCs) could explain more than 80% of the variability in the six samples analyzed. PC1 was associated with Ca and light REEs and interpreted as gypsum, whereas PC2 was associated with Y and heavy REEs, which were not clearly associated with a major sulfate. Finally, PC3 included Mg, Fe and several transition metals (Cu, Ni, Co, Mn and Zn) and was interpreted as Fe(II)-Mg sulfates. Selective dissolution of the salt mixtures with solutions saturated in the major sulfates revealed that the REEs were only retained in gypsum and were practically absent from the rest of the sulfates. The incorporation of REEs into gypsum decreased from Pr-Nd to La and Lu and was strictly ruled by the differences in their atomic radii and that of Ca in eight-fold coordination. However, gypsum concentrated less than 20% of the REE inventory (<?1% for Sc); the rest probably formed one or more unidentified trace minerals. This indicates that gypsum may not be an efficient way to concentrate REEs from AMD.

     

Geochemical Characterisation of Seepage and Drainage Water Quality from Two Sulphide Mine Tailings Impoundments: Acid Mine Drainage versus Neutral Mine Drainage

Seepage water and drainage water geochemistry (pH, EC, O₂, redox, alkalinity, dissolved cations and trace metals, major anions, total element concentrations) were studied at two active sulphide mine tailings impoundments in Finland (the Hitura Ni mine and Luikonlahti Cu mine/talc processing plant). The data were used to assess the factors influencing tailings seepage quality and to identify constraints for water treatment. Changes in seepage water quality after equilibration with atmospheric conditions were evaluated based on geochemical modelling. At Luikonlahti, annual and seasonal changes were also studied. Seepage quality was largely influenced by the tailings mineralogy, and the serpentine-rich, low sulphide Hitura tailings produced neutral mine drainage with high Ni. In contrast, drainage from the high sulphide, multi-metal tailings of Luikonlahti represented typical acid mine drainage with elevated contents of Zn, Ni, Cu, and Co. Other factors affecting the seepage quality included weathering of the tailings along the seepage flow path, process water input, local hydrological settings, and structural changes in the tailings impoundment. Geochemical modelling showed that pH increased and some heavy metals were adsorbed to Fe precipitates after net alkaline waters equilibrated with the atmosphere. In the net acidic waters, pH decreased and no adsorption occurred. A combination of aerobic and anaerobic treatments is proposed for Hitura seepages to decrease the sulphate and metal loading. For Luikonlahti, prolonged monitoring of the seepage quality is suggested instead of treatment, since the water quality is still adjusting to recent modifications to the tailings impoundment.     

煤矸石山酸性矿山废水的控制研究综述

综述煤矸石山酸性矿山废水的控制研究结果.传统的酸性矿山废水治理如碱性物质中和法、湿地处理法等为末端治理,而新的有效方法如杀菌剂法、表面钝化处理法、有机物质覆盖法等则从根本上控制煤矸石山酸性矿山废水的产生.     

Acute and Chronic Toxicity of Acid Mine Drainage to the Activated Sludge Process

The combined treatment of acid mine drainage (AMD) and municipal wastewater using the activated sludge process is an innovative approach to AMD remediation. The toxicity of synthetic AMD to activated sludge was evaluated using oxygen uptake rate (OUR) inhibition tests, which showed that activated sludge can withstand high proportions of AMD (EC₅₀ 19?C52% AMD by volume). The EC₅₀ values of municipal and industrial activated sludges were significantly different (p?<?0.05), with municipal sludges exhibiting higher tolerance to AMD. Although the EC₅₀ values for heterotrophic and nitrifying activated sludges were not statistically significantly different, the EC₅₀ values for heterotrophic bacteria were generally higher. Laboratory-based sequencing batch reactors were used to examine the treatability of AMD. Increased concentrations of COD and suspended solids, associated with turbidity and poor floc morphology, were observed in the final effluent after extended AMD loading. Protozoan community structure changed during the AMD loading period, and overall abundance tended to decrease over time. OUR decreased in the AMD-loaded reactors, particularly in the reactor receiving the highest AMD load, indicating reduced biomass activity over the acclimatization period. Results from OUR inhibition tests on the acclimatized activated sludge indicated that over a relatively short timescale (21?days), the activated sludge microbial community can adapt to AMD sufficiently so that shock loads of metals and acidity do not significantly inhibit OUR. These preliminary studies indicate that it is possible to treat AMD successfully in admixture with municipal wastewater using the activated sludge process.     

Review of Passive Systems for Acid Mine Drainage Treatment

When appropriately designed and maintained, passive systems can provide long-term, efficient, and effective treatment for many acid mine drainage (AMD) sources. Passive AMD treatment relies on natural processes to neutralize acidity and to oxidize or reduce and precipitate metal contaminants. Passive treatment is most suitable for small to moderate AMD discharges of appropriate chemistry, but periodic inspection and maintenance plus eventual renovation are generally required. Passive treatment technologies can be separated into biological and geochemical types. Biological passive treatment technologies generally rely on bacterial activity, and may use organic matter to stimulate microbial sulfate reduction and to adsorb contaminants; constructed wetlands, vertical flow wetlands, and bioreactors are all examples. Geochemical systems place alkalinity-generating materials such as limestone in contact with AMD (direct treatment) or with fresh water up-gradient of the AMD. Most passive treatment systems employ multiple methods, often in series, to promote acid neutralization and oxidation and precipitation of the resulting metal flocs. Before selecting an appropriate treatment technology, the AMD conditions and chemistry must be characterized. Flow, acidity and alkalinity, metal, and dissolved oxygen concentrations are critical parameters. This paper reviews the current state of passive system technology development, provides results for various system types, and provides guidance for sizing and effective operation.     

Long-term Performance of Passive Acid Mine Drainage Treatment Systems

Abstract.   State and federal reclamation programs, mining operators, and citizen-based watershed organizations have constructed hundreds of passive systems in the eastern U. S. over the past 20 years to provide reliable, low cost, low maintenance mine water treatment in remote locations. While performance has been reported for individual systems, there has not been a comprehensive evaluation of the performance of each treatment type for a wide variety of conditions. We evaluated 83 systems; five types in eight states. Each system was monitored for influent and effluent flow, ph, net acidity, and metal concentrations. Performance was normalized among types by calclating acid loading reductions and removals, and by converting construction cost, projected service life, and metric tonnes of acid load treated into cost per tonne of acid treated. Of the 83 systems, 82 reduced acid load. Average acid load reductions were 9.9 t/yr for open limestone channels (OLC), 10.1 t/yr for vertical flow wetland (VFW), 11.9 t/yr for anaerobic wetlands (AnW), 16.6 t/yr for limestone leach beds (LSB), and 22.2 t/yr for anoxic limestone drains (ALD). Average costs for acid removal varied from $83/t/yr for ALDs to $527 for AnWs. Average acid removals were 25 g/m²/day for AnWs, 62 g/m²/day for VFWs, 22 g/day/t for OLCs, 28 g/day/t for LSBs, and 56 g/day/t for ALDs. It appears that the majority of passive systems are effective but there was wide variation within each system type, so improved reliability and efficiency are needed. This report is an initial step in determining passive treatment system performance; additional work is needed to refine system designs and monitoring.     

Using Acid Mine Drainage to Recover a Coagulant from Water Treatment Residuals

We evaluated the recovery of aluminum from water treatment residuals by acidification using acidic coal mine drainage as an extraction solution. The water treatment residuals had Al and total Fe concentrations of 1.2 and 1.3%, respectively, based on mass. The influence of contact time of the mine water with the water treatment residuals and the percent of excess sulfate were assessed. The results showed that 28 min of contact and 100% of excess sulfate allowed recovery of >90% of the Al. Color was reduced from 25.9 to 0.8 total color units (TCU) and turbidity was reduced from 6 to 0 nephelometric turbidity units (NTU). The recovered coagulant performed appropriately in water treatment tests, based on physical–chemical parameters. The only parameter that requires more attention is antimony, which was close to the maximum concentration limits for drinking water.     

酸性矿山废水形成与处理中的微生物作用

介绍硫酸盐还原菌(SRB)法处理酸性矿山废水的机理、影响因素和发展现状,指出目前酸性矿山废水处理中存在问题并提出解决方法。     

Analysis of Acid Drainage Flow Zones in a Rocky Massif in a Uranium Mine from Structural and Geophysical Diagnoses

During its 13 years of non-continuous operation, the Osamu Utsumi Mine has generated serious environmental impacts. This mining complex is now attempting to decommission this uranium mine to reduce its environmental liabilities. As part of a hydrogeological analysis of the old Osamu Utsumi Mine pit area, a geophysical investigation was carried out along each front of the mine pit using electrical resistivity tomography and a dipole–dipole array. The lithology described in each front, the physical access, and data from monitoring wells also contributed to the geophysical interpretation and, hence, the hydrogeological analysis. The field results and geochemical data from monitoring wells enabled us to distinguish areas where water was flowing through fractures in the massif and areas with more acidic water, with electrical resistivity values less than 15 Ω m.

     

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。     

Assessment of Metals Loading in an Acid Mine Drainage Watershed

Watershed-scale modeling can be useful in identifying the main environmental factors and the physical mechanisms responsible for acid mine drainage (AMD) formation, attenuation, and impacts. Since flow rates and water quality of the AMD and receiving streams are related to the rainfall-runoff relationship and associated contaminant dissolution, we thought that hydrologic analysis of the mined area and surrounding drainage basin should be the starting point in documenting the source and fate of AMD contaminants. Further modeling of AMD pollutants could then be performed in terms of metal concentrations and loading at the watershed scale. In this study, monitoring was conducted in the Geopung mine watershed; the watershed analysis risk management framework (WARMF) model was used to evaluate the effect of AMD contributions to downstream metal concentrations. The hydrologic model of the basin was calibrated and verified with rainfall and streamflow data, and the water quality model was calibrated for the dissolved concentrations of metals (Cd, Cu, Zn, and Pb), using discharge data gathered in 2009. There was a strong correlation (r = 0.93) between the observed and simulated runoff values plus high Nash–Sutcliffe model efficiency (NSE = 0.89) and low average percent difference between predicted and measured values (%Diff = 0.46). Subsequent model validation using data gathered in 2010 also showed good agreement (%Diff = 9.76; NSE = 0.77; r = 0.91) between the observed and simulated values. For the metals, the model was calibrated using data from 2010; the correlation between the observed and simulated values was quite good (r = 0.80–0.41).     

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。