Mining and Toxic Metals

Posted by Stop Ajax Mine on December 8th, 2011 4:58pm

The following study was done by REDOIL (Resisting Environmental Destruction on Indigenous Lands) in Alaska related to the Donlin Creek Mine, and it contains a number of references that are applicable to the KGHM Ajax Mine. For example, the 'How Mining Releases Toxic Metals' section. 

Click here to download the full pdf report.

From the report:

How Mining Releases Toxic Metals


Large amounts of waste rock and tailings contaminated with toxic metals can be produced by mine sites. In the case of the Donlin Creek mine, there are only 0.072 ounces of gold for every ton of ore, a figure that does not take into account the waste rock. Toxic substances contained within the rock and tailings are more easily released once these substances are processed/milled and left in mine pits, underground workings, waste rock piles, and tailings impoundments where they are exposed to the environment.

Mercury can be released from waste rock and mine tailings directly into the atmosphere even at normal environmental temperatures because mercury evaporates at a much lower temperature than other metals. Once in the atmosphere, it can later be deposited in soils and waters miles from the mining site.

Dust emissions from the mine site during blasting and mining operations could contain any toxic metals that occur locally. For example, dust emissions at Alaska’s Red Dog mine are responsible for severely contaminating the surrounding environment with lead and cadmium. Rain water leaches toxic substances from waste rock and mine tailings into soil and waterways. Additionally, rain can deposit toxic metals from the air, present as vapours or attached to dust particles, into waterways.

One of the major sources of toxic metals associated with mining is acid mine drainage. When waste rock excavated from the mine is exposed to air (oxygen) and water, it chemically reacts to form several acids, including sulphuric acid. This acid leaches toxic metals from the rock and surrounding environment. Acid mine drainage is known to have very high concentrations of metals including iron, mercury, arsenic and antimony. Acid mine drainage may contaminate both surface and ground water.  Once acid mine drainage begins to form it is usually impossible to stop and is difficult and costly to remedy. According the EPA, the variable size and mineral composition of waste rock makes accurate prediction of AMD difficult.

The massive amounts of fossil fuels needed for large scale mining operations also contribute to the release of toxic metals into the atmosphere. Burning coal and petroleum releases toxic metals, specifically mercury, and other hazardous substances into the air. These toxic emissions are associated with cardiovascular problems, reproductive effects, cancer and other health problems. It is estimated that mining consumes 7-10 percent of the world’s energy production.

Additionally, seasonal variations in precipitation and temperature can have a significant impact on the concentrations of toxic metals and the effects on wildlife. Snowmelt from or through a mine site can potentially introduce considerable amounts of toxic metals and acidic water into ecosystems in a short period of time. The increased stresses of an arctic winter make arctic organisms more vulnerable to toxic exposures.


Nonie on 2011-12-15 18:15:40

Superb information here, ol'e chap; keep burning the midnight oil.

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