Acid Mines
Acid mines refer to abandoned or active mining sites where the exposure of sulfide minerals to air and water leads to the formation of acidic runoff. This runoff, known as acid mine drainage, can contaminate water sources and harm aquatic life. Acid mines are a significant environmental concern, and remediation efforts often involve neutralizing the acidic runoff and preventing further contamination.
6 Key excerpts on "Acid Mines"
eBook - ePubEnvironmental Impacts of Mining
Monitoring, Restoration, and Control, Second Edition
- Mritunjoy Sengupta(Author)
- 2021(Publication Date)
- CRC Press(Publisher)
...Key issues are whether the groundwater and surface water supplies will remain fit for human consumption and whether the quality of surface waters in the project area will remain adequate to support native aquatic life and terrestrial wildlife.1.8.2 Acid Mine Drainage and Contaminant LeachingPotential for the generation of acid mine drainage is a critical issue for determining whether a mining project is environmentally acceptable. When mined materials such as the walls of open pits and underground mines, tailings, waste rock heap, and dump leach materials are excavated and exposed to oxygen and water, acid can form if iron sulphide minerals (especially pyrite) are abundant andneutralize materials to counteract the acid formation. The acid will, in turn, leach or dissolve metals and other contaminants from mined materials and form a solution that is acidic, high in sulphate, and metal-rich, including elevated concentrations of cadmium copper, lead, zinc, arsenic, etc.Leaching of toxic constituents, such as arsenic, selenium, and metals, can occur even if acidic conditions are not present. Elevated levels of cyanide and nitrogen compounds (ammonia, nitrate, and nitrite) can also be found in waters at mine sites, from heap leaching and blasting.Acid drainage and contaminant leaching are the most important source of water quality impacts related to metallic ore mining. Acid mine drainage is considered one of mining’s most serious threats to water resources. A mine with acid mine drainage has the potential for long-term devastating impacts on rivers, streams, and aquatic life.If mine waste is acid generating, their impacts on fish, animals, and plants can be severe. Many streams impacted by acid mine drainage have a pH value 4 or lower, similar to battery acid...
eBook - ePub- Rattan Lal(Author)
- 2017(Publication Date)
- CRC Press(Publisher)
...Acid Mine Drainage Jerry M. Bigham School of Environment and Natural Resources, Ohio State University, Columbus, Ohio, U.S.A. Charles A. Cravotta III Pennsylvania Water Science Center, U.S. Geological Survey (USGS), New Cumberland, Pennsylvania, U.S.A. Abstract Acid mine drainage (AMD) consists of metal-laden solutions produced by the oxidative dissolution of iron sulfide minerals exposed to air, moisture, and acidophilic microbes during the mining of coal and metal deposits. The pH of AMD is usually in the range of 2–6, but mine-impacted waters at circumneutral pH (5–8) are also common. Mine drainage usually contains elevated concentrations of sulfate, iron, aluminum, and other potentially toxic metals leached from rock that hydrolyze and coprecipitate to form rust-colored encrustations or sediments. When AMD is discharged into surface waters or groundwaters, degradation of water quality, injury to aquatic life, and corrosion or encrustation of engineered structures can occur for substantial distances. Prevention and remediation strategies should consider the biogeochemical complexity of the system, the longevity of AMD pollution, the predictive power of geochemical modeling, and the full range of available field technologies for problem mitigation. INTRODUCTION Acid mine drainage (AMD) refers to metal-rich sulfuric acid (H 2 SO 4) solutions released from mine tunnels, shafts, open pits, and waste rock piles. Similar solutions can be produced by the excavation of roadways through certain rocks, dredging of harbor sediments, or drainage of coastal wetlands. Spoils and soils exposed to AMD tend to be sparsely vegetated and susceptible to erosion. When AMD enters waterways, increases in pH can result in the precipitation of metal hydroxide sediments, which smother aquatic habitats and clog the gills of fish and other aquatic life (Fig. 1). The corrosion of concrete and metal structures in contact with AMD, such as bridge pilings and pipes, is also greatly accelerated...
eBook - ePubBiotechnology of Metals
Principles, Recovery Methods and Environmental Concerns
- K.A. Natarajan(Author)
- 2018(Publication Date)
- Elsevier(Publisher)
...Chapter 13 Microbial Aspects of Acid Mine Drainage—Mining Environmental Pollution and Control Abstract Chemistry, types, and microbial aspects of acid mine drainage (AMD) are illustrated with examples. Primary factors influencing acid generation and water contamination from abandoned mines, mined over burden, and tailing dams are analyzed. Microbiology of AMD is discussed. Static and kinetic tests for prediction of acid drainage are brought out with respect to experimental and research protocols. Prevention, control, and remediation of AMD are critically discussed with special emphasis on active and passive methods. Bioremediation processes are highlighted with examples from commercial practices. A few case studies from industrial mining operations are illustrated to stress the commercial relevance of developed AMD remediation technologies. Keywords Acid mine drainage; microbiology; water contamination; bioremediation; wetlands; permeable reactive barriers Acid mine drainage (AMD) is generated under environmental conditions when sulfide minerals are exposed to oxygen, water, and acidophilic microorganisms. Mining, waste ore burden, tailings, and exposure of abandoned mines to the environment promote AMD, catalyzed by naturally occurring acidophilic chemolithotrophic bacteria. Also termed, acid rock drainage (ARD), this environmental problem is a challenging and costly task faced by coal and metal mining industries, all over the world. In the acid water formed, many toxic metals such as copper, arsenic, aluminum, zinc, and iron are dissolved. Several hundreds of thousand kilometers of streams and rivers around the world are degraded and polluted by AMD originating from abandoned surface and deep mines [1]. Chemistry and Types of AMD AMD is generated by the oxidation of sulfide minerals, mainly pyrite (FeS 2). Bacterially mediated pyrite and other sulfide mineral oxidation generate sulfuric acid containing ferric and other dissolved metal ions...
eBook - ePubEnvironmental Impact of Mining and Mineral Processing
Management, Monitoring, and Auditing Strategies
- Ravi Jain(Author)
- 2015(Publication Date)
- Butterworth-Heinemann(Publisher)
...Furthermore, metals present in the sulfide rich rock may partially dissolve in waters with low pH, increasing toxic metal concentrations and thus the detrimental impact on aquatic life and ecosystems (Jennings et al., 2008).The chemical and biological reactions associated with AMD are natural processes that usually occur slowly in undisturbed ore, posing little ecological threat (U.S. Environmental Protection Agency (U.S. EPA), 1994). However, in mining activities these processes are greatly accelerated by large land disturbances, greatly increasing contact of sulfide rich minerals to water and oxygen. The reactions responsible for AMD create a cyclical process that perpetuates the continual creation of AMD (Leading Practice Sustainable Development Program for the Mining Industry, 2007b).As a result, acid mine drainage can persist throughout the life of an active mine and long after it has been abandoned. Therefore, any activity that might result in the disturbance of sulfide rich materials should be prefaced with a full evaluation of AMD potential. During this evaluation, emphasis should be placed on preventing and mitigating AMD creation rather than treating AMD (Leading Practice Sustainable Development Program for the Mining Industry, 2007b), as perpetually treating AMD results in high ongoing costs.Formation of AMDAcid mine drainage can form from a number of sulfide minerals. Acid mine drainage reactions for pyrite (FeS2) are perhaps the best known and most studied, as pyrite is the most abundant sulfide mineral and is commonly found in metal and coal deposits throughout the world (Lottermoser, 2010).Pyrite is initially oxidized by water and oxygen to form sulfate and hydrogen ions (U.S. Environmental Protection Agency (U.S...
eBook - ePub- U. Aswathanarayana(Author)
- 2003(Publication Date)
- CRC Press(Publisher)
...washed), depending upon the requirements of the user. Depending upon the composition of coal (such as sulphur content), mining of coal may have consequences such as acid mine drainage (AMD) and burning of coal could cause acid rain, (6) the environmental impacts associated with the coal cycle are complex and interactive. They may be instantaneous (e.g. land clearance), accumulative (e.g. spoil deposition), or progressive (pneumoconiosis). The following account is largely drawn from Chadwick et al. (1987). The special feature of this excellent work is its particular reference to the mining problems of the developing countries. In most cases, mining is preceded by exploratory diamond drilling (Fig. 2.1 ; source: UNEP Tech., Rept., No. 5, 1991, p. 10) in order to get samples of the subsurface, and build a three-dimensional structure of the ore body. Figure 2.1 Diamond drilling, and collection of sludge samples (source: UNEP Tech. Rept., No. 5, 1991, p. 10). 2.2 MINE DESIGN PROCESS A large coal mining project is bound to have a profound effect on the economy of an area or region, in terms of investment, use of natural resources, employment, environmental impact, etc. The Design Process of a coal mine is a part of the Coal Project Development Cycle. The trickiest part of the exercise is the choice of technology to be adopted in mining, as considerations of national policy are involved – whether to go in for the most advanced and productive technology, or whether to opt for low-cost, low-productivity, labour-intensive technology. Figure 2.2 (source: Chadwick et al., 1987, p. 72) shows the relationship between the planning stages of a coalmine, and expenditure during a typical coal project development cycle. There are four phases of mine planning – Pre-feasibility studies, Conceptual planning and Full feasibility, Preliminary Design and Final Design...
eBook - ePubThe Water Crisis
Constructing solutions to freshwater pollution
- Julie Stauffer(Author)
- 2013(Publication Date)
- Routledge(Publisher)
...List of Terms abatement techniques: techniques used to prevent or minimize pollutant movement into ground-water, or to prevent contaminants in ground-water from reaching areas of clean, usable water; include the use of barriers, interceptor trenches and strategic pumping acid mine drainage: the effluent from bituminous coal mines or metal mines that contain a large concentration of acidic sulphates, including ferrous sulphate acid rain (also known as acidic deposition or acidic precipitation): precipitation that becomes more acidic than normal (i.e. a pH lower than 5.6) after falling through polluted air and dissolving the pollutants, primarily sulphur dioxide acidic deposition: see acid rain acidic precipitation: see acid rain acidification: the reduction in soil pH or the pH of a body of water activated sludge process: a common form of secondary sewage treatment that uses aerobic bacteria in a pond or tank that is continuously aerated adsorption: process in which a liquid or gas adheres to the outside of a solid without penetrating it aerobic: referring to conditions or processes in which oxygen is present algae: a group of relatively simple, mainly unicellular, aquatic plants that contain chlorophyll ambient standards: standards that establish permissible levels of pollutants in the environment, e.g...
