Mine drainage is formed when pyrite (an iron sulfide) is exposed and reacts with air and water to form sulfuric acid and dissolved iron. The acid runoff further dissolves heavy metals such as copper, lead, and mercury into groundwater or surface water. …
How is acid mine drainage caused?
Acid Mine Drainage (AMD) is currently the main pollutant of surface water in the mid-Atlantic region. AMD is caused when water flows over or through sulfur-bearing materials forming solutions of net acidity. AMD comes mainly from abandoned coal mines and currently active mining.
What type of mining causes acid mine drainage?
Acid mine drainage (AMD) occurs primarily when the mineral ore pyrite (FeS2) is exposed to water and oxygen from air, producing soluble iron and sulfuric acid. One reason that pyrite is important in AMD generation is that it forms under a variety of conditions and is widespread in different rock types.
What is acid drainage and where does it come from in a mining context?
What is acid drainage and where does it come from in a mining contex? Strip mining exposes sulfide minerals, which react with oxygen and water to produce sulfuric acid. This enters waterways, creating acid mine drainage.
How does acid mine drainage affect farming?
Water pollution is an ongoing problem; acid mine drainage, already at unacceptable levels, has led to the contamination of groundwater reserves. Air pollution results in acid rain, which reduces the quantity and quality of crops. The rehabilitation of mined soils is often never fully achieved.
What are the three effects of acid mine drainage?
Acid mine drainage (AMD) is the runoff produced when water comes in contact with exposed rocks containing sulfur-bearing minerals that react with water and air to form sulfuric acid and dissolved iron. This acidic run-off dissolves heavy metals including copper, lead, and mercury which pollute ground and surface water.
How can we prevent acid mine drainage?
Some common methods include: Reclamation of contaminated land by (1) adding lime or other alkaline materials to neutralize the acidity, and (2) adding uncontaminated top soil, planting vegetation, and modifying slopes to stabilize the soil and reduce infiltration of surface water into underlying contaminated material.
What is the threat of acid mine drainage?
Acid mine drainage is one of mining’s most serious threats to water. A mine draining acid can devastate rivers, streams, and aquatic life for hundreds, and under the “right” conditions, thousands of years.6 дней назад
What is the pH of acid mine drainage?
Acid drainage is caused by the oxidation of metallic compounds such as the mineral constituent of rocks and soils that is often present in coal mine slag. Most streams affected by coal mine drainage are acidic (pH 2.5 to 6.0), with high iron and sulfate concentrations.
Which ore leaves a great deal of acid mine drainage?
The most commonly mined ore of copper, chalcopyrite, is itself a copper-iron-sulfide and occurs with a range of other sulfides. Thus, copper mines are often major culprits of acid mine drainage.
What is the impact of acid mine drainage on the environment?
Acid mine drainage is often encouraged by a biological feedback loop. Once acid mine drainage starts, certain microbes thrive in the acidic environment. These microbes increase the production of sulfuric acid from the surrounding rock, further poisoning the downstream environment for other organisms.5 мая 2010 г.
How does acid mine drainage affect humans?
Because of concentration levels, AMD can be 20 to 300 times more acidic than acid rain and can burn human skin and kill fish and other aquatic life. AMD also leaches toxic metals, including arsenic, cadmium, chromium, and lead from waste rock which can cause further pollution.
What causes acid mine drainage in South Africa?
Groundwater after mining
This groundwater started to dissolve the iron hydroxides on the rock walls of the mine, often creating very poor water quality, including very acidic conditions. The resulting poor quality groundwater is often called acid mine drainage.
In which South African province is the problem of acid rain particularly bad?
Acid particles in the air are suspected of contributing to respiratory problems in people. The coal burning power stations and large metal working industries of South Africa are concentrated in the Eastern Transvaal Highveld, the industrial heart of the country.