Amd is caused when water flows over or through sulfurbearing materials forming solutions of net acidity. Mar, 2019 most rock extraction sites, including mine sites and building construction sites, require a plan to assess, and mitigate if present, the risk of acid mine drainage amd. Sgs acid rock drainage ard services can help you to minimize environmental liabilities by predicting the outflow of acidic water from mining and other geotechnical operations. Acid mine drainage amd from mining wastes is one of the current environmental problems in the field of mining pollution that requires most action measures. There are four chemical reactions that represent the chemistry of pyrite weathering to form acid mine drainage. Acid mine drainage terms acid mine drainage amd water that is polluted from contact with mining activity acid rock drainage ard natural rock drainage that is acidic both produce acidic waters how to distinguish. In pennsylvania, reported aluminum concentrations in discharge samples from 140 abandoned coal mines showed that over.
In this lecture we discuss weathering, acid rock drainage and methods for prevention and mitigation. Pure neutral water has a ph of 7, acids have a ph less than 7 and. The acid mine drainage may also contain high amounts of co2 which forms carbonic acid and further depresses the ph. Acid mine drainage prevention and control options nural kuyucak golder associates ltd.
Also learn about the impact of construction projects on this phenomenon. Innovative treatment technologies purpose currently there is no comprehensive survey about the types of remediation technologies being used to treat abandoned mines. The global acid rock drainage guide pdf about 126 mb. Ard forms as a result of the dissolution of sulphides, mainly pyrite fes 2 and pyrrhotite fes. Major impact areas are rivers, lakes, estuaries and coastal waters, although amd affects different aquatic ecosystems in different ways. Oct 19, 2011 we suggest that the cr enrichment beginning 2. The oxidation of sulphidic mine wastes and the consequent release of acid mine drainage and acid rock drainage, is one of the main strategic environmental issues facing the mining industry. The net result of acid generating andneutralizing reactions within mining wastes is termed acid rock drainage ard. Management and mitigation of acid mine drainage in south. Mar 19, 2014 learn about how acid can naturally be generated from rocks exposed at the earths surface. Acidrock drainage occurs through the interaction of rainfall on pyritebearing formations. The problem of acid rock drainage acid rock drainage ard, often referred to as acid mine drainage ard, can be defined as the drainage that occurs as a result of natural oxidation of sulphide minerals contained in rock which is exposed to air and water. We offer a complete range of solid phase geochemical analysis, static testing, leaching procedures shake flask extraction sfe, synthetic precipitation leaching procedure splp, and toxicity characteristic leaching procedure tclp, net acid generation nag, and kinetic testing. Jonathan run is a tributary of beech creek that is impacted with fill material containing acid rock and clay during the construction of i80 in centre county, pennsylvania.
Trace element geochemistry and acid rock drainage acid. The effect of acid mine drainage amd can occur indefinitely and as such its impact is not only felt by the existing mining operations but also on the environment and associated communities long after mining has ended. Environmental impact and remediation of acid mine drainage. When fully exposed to air and water, the chemical reactions forming amd occur at a faster rate. Learn about how acid can naturally be generated from rocks exposed at the earths surface. Techniques to correct and prevent acid mine drainage. Ard is often mislabelled amd or acid mine drainage too.
Unexpected nonacid drainage from sulfidic rock waste. Miw can contain metals, metalloids and other constituents in concentrations above regulatory standards. Acid mine drainage amd causes environmental pollution that affects many countries having historic or current mining industries. Acid mine drainage overview acid rock drainage ard is produced by the oxidation of sulfide minerals, chiefly iron pyrite or iron disulfide fes2. Sulfur reduction in acid rock drainage environments. Trace element geochemistry and acid rock drainage acid mine.
This is a natural chemical reaction which can proceed when minerals are exposed to air and water. Work carried out at the abandoned copper cu and sulphur s mine at avoca south east ireland has shown acid mine drainage amd to be a multifactor pollutant. Dissolution and alteration of various minerals can contribute to the neutralization of acid. We offer a complete range of solid phase geochemical analysis, static testing, leaching procedures shake flask extraction sfe, synthetic precipitation leaching procedure splp, and toxicity characteristic leaching procedure tclp, netacid generation nag, and kinetic testing. Development of the global acid rock drainage guide. Agat laboratories offers fullservice analysis capabilities for ard testing. Acid mine drainage amd is typically characterized by low ph and high dissolved iron. Acid rock drainage analysis and testing services acid rock drainage ard also known as acid mine drainage amd describes the formation of acid when sulphidebearing mine wastes principally pyrite, but also pyrrhotite and chalcopyrite are exposed to oxidising conditions, typically in the presence of. Effects of acid mine drainage on the release of aluminum. The following is an overview of information on some major. So, to better understand amd and ard, lets begin by defining some terms like ph the standard measure of acidity.
There are four chemical reactions that represent the chemistry of pyrite weathering to. The highest levels of sulfide in the enrichments were detected at ph 3 with hydrogen and ph 4 with acetate. Next, it describes selected metals most frequently associated with acid rock drainage. The development of the global acid rock drainage gard guide is sponsored by inap with the support of the global alliance. It affects aquatic ecosystems by a number of direct and indirect pathways. Laboratory acid rock drainage ard prediction tests are used to determine the most appropriate disposal options for waste rock and tailings in order to minimize environmental impact bureau veritas offers the full range of ard testing services for prediction studies and routinely conducts geochemical analysis, static testing and kinetic test programs. Acid mine drainage, acid and metalliferous drainage amd, or acid rock drainage ard is the outflow of acidic water from metal mines or coal mines acid rock drainage occurs naturally within some environments as part of the rock weathering process but is exacerbated by largescale earth disturbances characteristic of mining and other large construction activities, usually within rocks. Acid rock drainage ard and metal leaching affect the quality of water, soil, plant, and fish habitat in terms of trace elements, in both toxic or nontoxic, and bioavailable or nonavailable forms. Nowadays, simple tests are widely applied and established in the mining and consulting business for ard prediction. The formation of acid mine drainage and the contaminants associated with it have been described as the largest environmental problem facing the u. Microbiological suitability of acidophilic sulfur reduction for metal recovery was explored by enriching sulfur reducers from acidic sediments at low ph from 2 to 5 with hydrogen, glycerol, methanol and acetate as electron donors at 30 c.
Acid rock drainage ard is produced by the oxidation of sulfide minerals, chiefly iron pyrite or iron. The objective of this phd research was to investigate the leaching of acid clays with acid mine rock drainages amdard typically found in u. An in situ ftir study of galena and pyrite oxidation in aqueous solution. Aquatic organisms assimilate metals from the dissolved content of the surrounding water and from metals contained in. The purpose of this paper is to provide information about this topic with a particular focus on hard rock mining sites. Major environmental incidents caused by acid mine drainage. Acid mine drainage and its control measures submitted by. Corroding effects of acid on parts of infrastructure such as bridges acid mine drainage mines built as early as the 1800s were developed in a manner which utilized gravity drainage, to avoid excessive water accumulation in the mines as a result, water polluted by acid, iron, sulfur and aluminum drained away from the mines and into streams. The production of broken waste rock and tailings by mining operations can expose large amounts of pyrite and other sulphides to the effects of water and oxygen.
This example shows that natural acid rock drainage can affect water quality as well as acid mine drainage. Acid rock drainage and climate change sciencedirect. Metals associated with acid rock drainage and their effect on. In the case of iron and manganese, these metals are generally. This pdf of the gard guide can be downloaded and printed. Effects of acid mine drainage on the release of aluminum from. On the neutralization of acid rock drainage by carbonate. Council has commissioned two reports to assess the causes and extent of the ard, and recommending remedial treatment options. Metals associated with acid rock drainage and their effect.
Aerobic bacterial pyrite oxidation and acid rock drainage. Pdf acid mine or acid rock drainage jorge g ibanez. Acid rock drainage some bedrock contains minerals that can generate acid rock drainage ard. Acid rock drainage ard is the natural result of oxidizing or rusting of certain types of sulfurbearing minerals in the presence of water, air and bacteria. Acid rock drainage occurs naturally within some environments as part of the rock weathering process but is exacerbated by largescale earth disturbances construction sites. The gard guide was created through the contributions of many individuals and organizations. Acid rock drainage as a concern and part of all metals and mining operations. Acid mine drainage, acid and metalliferous drainage amd, or acid rock drainage ard is the outflow of acidic water from metal mines or coal mines. Bibliography for acidrock drainage and selected acidmine. The oxidation of sulfide minerals is the major contributor to acid generation. Reference guide to treatment technologies for mining.
The density of sulphidic ore deposits in a few noteworthy catchments, the semiarid southern african climate, long history of mining as well as acid and neutral rock drainage ard and nrd are the main strategic environmental issues that the. Acid mine drainage prediction compares acid rock drainage factors of waste rock piles and tailings impoundments. In examining this table, it is important to note that diffusion of oxygen into water is slow and, therefore, oxidation of iron sulfide is inhibited until the water level drops, which can occur periodically or seasonally in some cases. On the neutralization of acid rock drainage by carbonate and. Characteristics increased acidity decreased ph increased metal concentrations increased sulfate increased suspended solids all. When pyrite fes 2 is exposed to oxygen and water in mine workings or roadcuts, the mineral decomposes and sulfur may react to form sulfuric acid, which often results in environmental problems and potential damage to the transportation infrastructure. Acid rock drainage ard, also referred to as acid mine drainage amd, is the outflow of acidic water from mining operations including waste rock, tailings, and exposed surfaces in open pits and underground workings.
Acid rock drainage prediction manual mend project 1. Acid rock drainage from sulphide minerals is the most significant environmental impact from mines. Pdf acid mine drainage formation, control and treatment. The major areas of research on amd are prediction of amd and preventionmitigation. Acid rock drainage analysis and testing services acid rock drainage ard also known as acid mine drainage amd describes the formation of acid when sulphidebearing mine wastes principally pyrite, but also pyrrhotite and chalcopyrite are exposed to oxidising conditions, typically in the presence of water, due. Problems associated with mine drainage contaminated drinking water disrupted growth and reproduction of aquatic plants and animals corroding effects of acid on parts of infrastructure such as bridges acid mine drainage mines built as early as the 1800s were developed in a manner which utilized gravity drainage, to avoid excessive water accumulation in the mines. The chapter further describes the uptake of these metals by fish and other aquatic organisms. Acid rock drainage ard prediction is a very important issue in order to predict and prevent environmental pollution associated with mining activities. Trace element geochemistry should not be limited to acid rock generation sites but also be applied to any project that involves creating, removal. This is a natural chemical reaction which can proceed. The net result of acidgenerating andneutralizing reactions within mining wastes is termed acid rock drainage ard. Miw affects over 10,000 miles of receiving waters in the united states, primarily by acidic drainage.
Our ard services analyze the acidproducing potential of ores on your site, predicting the problem and preventing longterm environmental liabilities. Aquatic organisms assimilate metals from the dissolved content of the surrounding water and from metals contained in diet items. This acid leaches out metals in the rock, which can enter nearby. Report on acid rock drainage ard investigations and remedial solutions ecoroc pty ltd. Most rock extraction sites, including mine sites and building construction sites, require a plan to assess, and mitigate if present, the risk of acid mine drainage amd. Research efforts have proceeded recently through the acid drainage technology initiative. The acidic discharges into jonathan run contain white aluminum precipitates resulting in surface water quality degradation and loss of sustaining aquatic life.
The processes responsible for its formation are autocatalytic and once it occurs on a large scale, it cannot be stopped. Measures to counteract acid rock drainage ard generation need to start at the mineral surface, inhibiting mineraloxidizing, acidophilic microbes. The source of these acidic waters if from naturally mineralized areas devoid of any mining activities. The most significant environmental impact from mines results from minerals that weather and release potentially harmful elements into water resources. Acid generation occurs when sulphide minerals and elemental sulphur are exposed to the. Acid mine drainage ferric iron acidithiobacillus ferrooxidans permeable reactive barrier iron sulfide formation. Typically in nova scotia, ard occurs when pyrite and other sulphide minerals are exposed to water and oxygen, and react in a chemical oxidation process that releases sulphuric acid and metal oxides into watercourses downstream. The ph scale actually measures hydrogen ion concentration in water solutions. The objective of this phd research was to investigate the leaching of acid clays with acid minerock drainages amdard typically found in u. Cost 1 mitigation measures are required when there is a need to prevent metal leaching or acid rock drainage impacts to other resources.
Highly acidic water with elevated levels of dissolved metals. Acid mine drainage formation, control and treatment. Drainage from surface or deep coal or metal mines and coal refuse piles. South africa has a mining history that started at the end of the 19 th century and has played a substantial role in the international mining sector.
Acid mine drainage research acid mine drainage amd has been the subject of intensive research since the 1960s. The purpose of this research is to identify sources of acid. A rainstorm event on september 19, 2002, in the red river valley is shown by the rapid. Acid mine drainage solutions for the mineral industry.
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