How is acid mine drainage treated?
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.
Does gold mining cause acid mine drainage?
The origin of acid mine drainage Acid mine drainage (also sometimes referred to as acid rock drainage) is a well-understood process2 and arises primarily when the mineral pyrite (‘fool’s gold’ or iron disulphide) comes into contact with oxygenated water.
What chemicals are involved in developing acid mine drainage?
Mine drainage is formed when pyrite (an iron sulfide) is exposed and reacts with air and water to form sulfuric acid and dissolved iron. Some or all of this iron can precipitate to form the red, orange, or yellow sediments in the bottom of streams containing mine drainage.
What is the current standard treatment for acid mine drainage contaminated water?
“Currently, the standard treatment for AMD is to aerate the water to oxidise the iron and add lime to bring the pH up. The iron then precipitates out – and most heavy metals along with it – in a deep red colour.
What are four causes of acid mine drainage?
Acid mine drainage is the formation and movement of highly acidic water rich in heavy metals. This acidic water forms through the chemical reaction of surface water (rainwater, snowmelt, pond water) and shallow subsurface water with rocks that contain sulfur-bearing minerals, resulting in sulfuric acid.
What would the steps be to restore a surface mine?
Reclamation includes the following steps: contouring of land; placement of topsoil or an approved substitute on the graded area; reseeding with native vegetation, crops and/or trees; and years of careful monitoring to assure success.
What does acid mine drainage look like?
Acid drainage is often marked by “yellow boy,” an orange-yellow substance (visible in the photo on this page) that occurs when the pH of acidic mine-influenced water raises above pH 3 (approaching more neutral conditions), so that the previously dissolved iron precipitates out.
What is used to neutralize the acid?
To neutralize acids, a weak base is used. Bases have a bitter or astringent taste and a pH greater than 7. Common bases are sodium hydroxide, potassium hydroxide and ammonium hydroxide. Bases are neutralized by using a weak acid.
What is acid mine drainage?
What are two ways we can reduce environmental damage done by strip mining?
Discover five ways the mining industry can reduce environmental impact and make its practices more sustainable.
- Lower-Impact Mining Techniques.
- Reusing Mining Waste.
- Eco-Friendly Equipment.
- Rehabilitating Mining Sites.
- Shutting Down Illegal Mining.
How are acid spills treated?
Acid/Bases Acids can be neutralized with soda ash or sodium bicarbonate whereas bases can be neutralized with citric acid or ascorbic acid. Following neutralization, the pH of the spill should be checked to ensure that the spill has been neutralized.
What are neutralizing agents?
Amines are used as neutralizing and or buffering agents in emulsifiable and synthetic fluids. Our products are free of secondary amines and cause almost no cobalt leaching. In many cases they improve the emulsion formation.
How do Acidophiles protect themselves from low pH?
Some have also evolved active pH regulation, which gives them the ability to pump hydrogen ions out of their cells at a constantly high rate. By doing this they are able to keep their internal pH at around 6.5—7.0.
What is the most environmental friendly action for the mining company after extraction of mineral?
One solution to becoming more environmentally sustainable is to reduce the input of the mine. By diverting surface water and pumping groundwater, mines can reduce both the quantity and quality of water available downstream for aquatic ecosystems and other use.
What can be done to restore the environment after strip mining?
After the coal is stripped, mine companies are legally required to do some restoration, which usually involves replacing the exploded soil and rock—rubble—covering it with a layer of topsoil, and seeding it with anything that will hold the ground together.
Why is acid drainage bad?
Heavy metals can be leached from rocks that come in contact with the acid, a process that may be substantially enhanced by bacterial action. The resulting fluids may be highly toxic and, when mixed with groundwater, surface water and soil, may have harmful effects on humans, animals and plants.
How should we deal with acid mine drainage in the Witwatersrand?
The report outlines short-term, medium-term and long-term action plans for dealing with acid mine drainage in the Witwatersrand area. It basically recommends: Pumping and treating water from the mine voids (the underground mining areas that are filling up with toxic water).
When was the acid mine drainage assessment completed?
This assessment was completed by August 2013. This experience has enhanced SRK’s knowledge of understanding problems and solutions associated with the increasing recognition of acid mine drainage (AMD) in the mining industry.
Is mine water in Gauteng dangerous?
Mine water has been prioritised because of the many hazards of acidic water. The serious ramifications of AMD in the West Rand Basin (one of three mining basins in Gauteng) was first recognised in 2002.
What are the effects of acid mining in South Africa?
On the West Rand, near Krugersdorp the decant (flow onto the surface of the ground) of acid mine drainage “has had a devastating effect on the ecology in the areas immediately downstream of the decant and has degraded streams and groundwater which feed the Cradle of Humankind World Heritage Site.” (ToE report to IMC, page 86)