How does acid mine drainage happen?

How does acid mine drainage happen?

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.

Why is mine water acidic?

If sulphur mixes with water and oxygen it can cause groundwater to become acidic. This is called acid mine drainage (AMD). Contaminated water from spoil heaps and stockpiles of crushed and waste rock can also create an acidic discharge called acid rock drainage (ARD), although the term AMD is often used to cover both.

Can mining cause acid rain?

When the mining process exposes the sulfides to water and air, together they react to form sulfuric acid.

How does mining affect the water?

Mining affects fresh water through heavy use of water in processing ore, and through water pollution from discharged mine effluent and seepage from tailings and waste rock impoundments. Mining by its nature consumes, diverts and can seriously pollute water resources.

Where is acid mine drainage?

Acid mine drainage can be released anywhere on the mine where sulfides are exposed to air and water — including waste rock piles, tailings, open pits, underground tunnels, and leach pads.

How can we stop 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.

How do you clean acid mine drainage?

Why is AMD such a problem when a mine closes?

AMD is a significant and costly environmental challenge facing the mining industry worldwide. The lack of knowledge or uncertainty as to the effectiveness of the waste management strategies being used has left mine owners and the State facing significant long term complications.

How can we prevent acid mine drainage?

The most prevalent method for treating AMD contamination is the addition of alkaline reagents such as lime, limestone, sodium carbonate or sodium hydroxide. This treatment aims at neutralizing acidic water and the precipitation of heavy metals.

How can we prevent mining from running off?

What are the bad effects of mining?

Across the world, mining contributes to erosion, sinkholes, deforestation, loss of biodiversity, significant use of water resources, dammed rivers and ponded waters, wastewater disposal issues, acid mine drainage and contamination of soil, ground and surface water, all of which can lead to health issues in local …

Does mining use a lot of water?

Mining uses water primarily for mineral processing, dust suppression, slurry transport and employees’ needs. In many cases, especially with underground mining, water needs to be pumped away from a mine site, which can reduce the levels of ground water, deplete surface water or cause pollution to local rivers.

How is water used in mining?

Mining water use is water used for the extraction of minerals that may be in the form of solids, such as coal, iron, sand, and gravel; liquids, such as crude petroleum ; and gases, such as natural gas. The category includes quarrying, milling of mined materials, injection of water for secondary oil recovery or for unconventional oil…

What causes acid mine drainage?

In a nutshell, acid mine drainage is a form of water pollution that happens when rain, runoff, or streams come in contact with rock that is rich in sulfur. As a result, the water becomes very acidic and damages downstream aquatic ecosystems.

How does mine drainage occur?

How does mine drainage occur? 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. The acid runoff further dissolves heavy metals such as copper, lead, and mercury into groundwater or surface water.

Is mining land pollution?

Mining has a huge impact on the environment and is a large cause of land pollution. Surface mining causes the destruction of existing plant life. Mining related activities destabilizes the land structures that are in the area of the mines and increases soil erosion.