Acid mine drainage (AMD) contamination in coal mines and the need for extensive prediction and remediation: a review (original) (raw)
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Acid Mine Drainages – Occurrence , Properties and Impact on the Environment
2018
Intensive exploitation and copper ores processing are associated with the formation of large quantities of solid waste such as mine dumps and flotation tailings. The predominant sulfide mineral which occurs in these wastes is pyrite. Under natural conditions, the availability of oxygen and atmospheric water on waste dumps brings about the initial spontaneous dissolution of pyrite and generation of sulphuric acid, which enables leaching of other less abundant sulphide minerals and oxide minerals contained in the ore. The presence of certain indigenous species of bacteria has a favourable effect on these processes, which eventually leads to the generation of mine waters. As a result of weathering, the products of oxidation are dissolved and leached in the form of acid mine drainages (AMDs), whose influence on the environment is extremely harmful due to a high content of heavy metal ions (Cu, Zn, Pb, As, Cd, Ni, Mn etc.) and sulphuric acid (Eigbor et al., 2007; Stanković et al., 2009; ...
Geochemical characteristics of acid mine drainage and sediments from coal mines
2007
The attenuation of mining activity in the Slovak Republic that started in 1989 led to the extensive closing of deposits using wet conservation, i.e. flooding. Negative effects of AMD can be observed mainly in the localities where sulphide ores and sulphide-containing raw materials used to be mined. The Smolník deposit is one of the historically best-known and richest Cu-Fe ore deposits in the Slovak Republic. The discharging mine waters of pH 3.7 containing high concentrations of sulphates, Fe, Mn, Cu, Zn, Al have a negative effect, mainly on the Smolník stream. In order to propose an effective and economically acceptable remediation method to prevent the negative influence of AMD on this locality, a regular monitoring of AMD quality was carried out. The article presents the results of monitoring carried out in 1986-2006. The geochemical modeling of AMD quality was also realized. It was aimed at the simulation of AMD evolution during its gradual ascent from the depth of 200 m to the surface when reacting with pyrite. On the basis of modelling results it is assumed that the amorphous ferric hydroxide, jarosite and pyrolusite will gradually precipitate.
Water
Mining activities at the Portuguese sector of the Iberian Pyrite Belt (IPB) have been responsible for the pollution of water, sediments, and biota, caused by the acid mine drainage (AMD) from the tailing deposits. The impact has been felt for years in the rivers and streams receiving AMD from the Aljustrel mine (SW sector of the IPB, Portugal), such as at the Água Forte stream, a tributary of the Roxo stream (Sado and Mira Hydrographic Region). To evaluate the extent of that environmental impact prior to the remediation actions, surface water, sediments, and the macrophyte Scirpus holoschoenus L. were sampled at the Água Forte and the Roxo streams, upstream and downstream from the confluence. The surface water and the sediments were extremely acidic at the Água Forte stream (pH ranges 2.22–2.92 for the water and 2.57–3.32 for the sediment), with high As, Cu, Pb, and Zn concentrations of 2.1, 120, 0.21, and 421 mg kg−1, respectively, in the water, and 661, 1746, 539, and 1994 mg kg−1...
Applied Geochemistry, 2010
Editorial handling by A. Kolker a b s t r a c t Coal mine rejects and sulfide bearing coals are prone to acid mine drainage (AMD) formation due to aqueous weathering. These acidic effluents contain dissolved trace and potentially harmful elements (PHEs) that have considerable impact on the environment. The behavior of these elements in AMD is mainly controlled by pH. The focus of the present study is to investigate aqueous leaching of mine rejects for prediction of acid producing potential, rates of weathering, and release of PHEs in mine drainage. Mine reject (MR) and coal samples from the active mine sites of Meghalaya, India typically have high S contents (1.8-5.7% in MR and 1.7-4.7% in coals) with 75-90% of the S in organic form and enrichment of most of the PHEs in rejects. Aqueous kinetic leaching experiments on mine rejects showed high acid producing potential and release of trace and potentially harmful elements. The elements (Sb, As, Cd, Cr, Co, Cu, Pb, Mn, Ni, V and Zn) in mine sample leachates are compared with those in mine waters. The concentrations of Al, Si, P, K, Ti, Mn, Fe, Co, Ni, Cu, Zn and Pb are found to increase with leaching time and are negatively correlated with pH of the solution. The processes controlling the release of these elements are acid leaching, precipitation and adsorption. The critical loads of PHEs in water affected by AMD are calculated by comparing their concentrations with those of regulatory levels. The Enrichment Factors (EFs) and soil pollution indices (SPIs) for the elements have shown that PHEs from coal and mine reject samples are mobilized into the nearby environment and are enriched in the associated soil and sediment.
Remediation of Acid Mine Drainage-Impacted Water
Current Pollution Reports, 2015
The formation of acid mine drainage (AMD), a highly acidic and metal-rich solution, is the biggest environmental concern associated with coal and mineral mining. Once produced, AMD can severely impact the surrounding ecosystem due to its acidity, metal toxicity, sedimentation and other deleterious properties. Hence, implementations of effective post-mining management practices are necessary to control AMD pollution. Due to the existence of a number of federal and state regulations, it is necessary for private and government agencies to come up with various AMD treatment and/or control technologies. This review describes some of the widely used AMD remediation technologies in terms of their general working principles, advantages and shortcomings. AMD treatment technologies can be divided into two major categories, namely prevention and remediation. Prevention techniques mainly focus on inhibiting AMD formation reactions by controlling the source. Remediation techniques focus on the treatment of already produced AMD before their discharge into water bodies. Remediation technologies can be further divided into two broad categories: active and passive. Due to high cost and intensive labor requirements for maintenance of active treatment technologies, passive treatments are widely used all over the world. Besides the conventional passive treatment technologies such as constructed wetlands, anaerobic sulfate-reducing bioreactors, anoxic limestone drains, open limestone channels, limestone leach beds and slag leach beds, this paper also describes emerging passive treatment technologies such as phytoremediation. More intensive research is needed to develop an efficient and cost-effective AMD treatment technology, which can sustain persistent and long-term AMD load.
Prediction and Remediation of Water Quality in Monitoring Potential of Acid Mine Drainage
American Journal of Engineering and Applied Sciences
Acid Mine Drainage (AMD) associated with both active and abandoned mining operations related to sulfide minerals, oxidation of pyrite affording an acidic solution that contains toxic metal ions. Result shows that pH value of water in Kg. Aur, Chini and Sg. Lembing are acidic with value of 2.81, 4.16 and 3.60 respectively. Maximum concentrations of heavy metals in the study area are: Pb (0.2 mg/L), Cd (0.05 mg/L), Zn (5.1 mg/L), Cu (5.2 mg/L), Mn (10.9 mg/L), Cr (0.2 mg/L), Ni (0.2 mg/L), As (0.005 mg/L) and Fe (202.69 mg/L). Prediction of acid formation using acid-base calculations from all samples shows high potential acid production between 22.84-2500.16 kg CaCO 3 /tonne. The ratio of Neutralization (NP) with Acid Potential (APP) shows a very low value (ratio<1) Sg. Lembing (0.02), Chini (0.08), Selinsing (0.31) and Kg. Aur (0.81). Analysis from the tank experiment after 30 days shows pH of LFS, bentonite, activated carbon and zeolite change to 6.11, 3.91, 2.98 and 2.71 respectively. Three mine sites experiencing AMD are Kg. Aur, Chini and Sg. Lembing. Active neutralization treatment successfully shows LFS has great potential to control AMD based on their ability to neutralize the pH and remove heavy metals in the mine water. Meanwhile, the second adsorbent material is bentonite followed by activated carbon and zeolite.
Hydrogeochemistry and Microbiology of Mine Drainage: An Update
Applied Geochemistry, 2015
The extraction of mineral resources requires access through underground workings, or open pit operations, or through drillholes for solution mining. Additionally, mineral processing can generate large quantities of waste, including mill tailings, waste rock and refinery wastes, heap leach pads, and slag. Thus, through mining and mineral processing activities, large surface areas of sulfide minerals can be exposed to oxygen, water, and microbes, resulting in accelerated oxidation of sulfide and other minerals and the potential for the generation of low-quality drainage. The oxidation of sulfide minerals in mine wastes is accelerated by microbial catalysis of the oxidation of aqueous ferrous iron and sulfide. These reactions, particularly when combined with evaporation, can lead to extremely acidic drainage and very high concentrations of dissolved constituents. Although acid mine drainage is the most prevalent and damaging environmental concern associated with mining activities, generation of saline, basic and neutral drainage containing elevated concentrations of dissolved metals, non-metals, and metalloids has recently been recognized as a potential environmental concern. Acid neutralization reactions through the dissolution of carbonate, hydroxide, and silicate minerals and formation of secondary aluminum and ferric hydroxide phases can moderate the effects of acid generation and enhance the formation of secondary hydrated iron and aluminum minerals which may lessen the concentration of dissolved metals. Numerical models provide powerful tools for assessing impacts of these reactions on water quality. Published by Elsevier Ltd. 1.1.2. Saline drainage Saline waters are defined somewhat differently depending on the chosen literature source and the water type. Salinity is defined
Acid mine drainage formation, control and treatment: Approaches and strategies
The Extractive Industries and Society, 2019
Acid mine drainage (AMD) occurs after mining exposes metal sulfides to oxidizing conditions. Leaching of reaction products into surface waters pollute over 20,000 km of streams in the USA alone. The coal mine permitting process requires prediction of AMD potential via overburden analysis. Where a potential exists, AMD control measures including spoil handling plans, alkaline amendment, and oxygen barriers or water covers may be required to stop or hinder AMD generation. Other AMD control technologies include injection of alkaline materials (coal ashes and limestone products) into abandoned underground mines and into buried acid material in mine backfills, remining of abandoned areas, and installation of alkaline recharge trenches. Where AMD already exists, effluent treatment is required. Active treatment includes adding alkaline chemicals such as Ca (OH) 2 , CaO, NaOH, Na 2 CO 3 , and NH 3 , but chemical treatment is costly, requires dispensing equipment and facilities, and often extends for decades. Passive treatment systems may also be employed to treat problem drainages and are effective under certain flow and acidity conditions. Such systems include aerobic and anaerobic wetlands, anoxic limestone drains, vertical flow wetlands, open limestone channels, and alkaline leach beds. This article discusses the process of AMD formation, preventative and control measures, and describes treatment methods for existing AMD discharges.