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TAILINGS

Tailings (also known as tailings pile, slickens[1] or gangue) are the waste materials left over[2] after removing the minerals from ore.

Tailings and gangue represent external costs of mining. As mining techniques and the price of minerals improve, it is not unusual for tailings to be reprocessed using new methods, or more thoroughly with old methods, to recover additional minerals.

In coal and oil sands mining, the word 'tailings' refers specifically to fine waste suspended in water and the word 'gangue' is not used.

Contents

Effects on the environment

Certain types of extraction methods, like heap leaching for example, leave behind toxic compounds in the tailings. Large-scale operations often leave huge piles of this material on site. Particles of toxic metals blown by the wind or leached by rainfall can contaminate surface water and groundwater. In other cases, tailings are specifically disposed of in bodies of water, raising the issue of water pollution.

A specific method of disposal called submarine tailings disposal (STD), is outlawed in the United States via the Clean Water Act, and in most other locations in the developed world. It was used by Utah Construction and Mining Ltd. at the Island Copper Mine in Canada from 1971 until 1995.[3] These standards are not always established or enforced in the developing world.[4] STD was selected as the lowest-impact disposal method for the Minahas Mine at Buyat Bay in Indonesia.[5][6] Transnational mining companies, like Newmont Mining, Placer Dome, Rio Tinto Group and BHP Billiton, have come under attack for operating or planning STD at mines throughout the Asia-Pacific region. The International Council on Mining and Metals asserts that STD should not be banned outright, but considered as an alternative to other disposal solutions where appropriate.[7]

Often, as in the case of riverbed metal extraction, this has buried valuable river-flat soils under the largely worthless and often contaminated tailings. Modern extraction methods have resulted in less damage but land rehabilitation continues to be a major problem and costly consideration.

Common contents of tailings

External links

Footnotes

  1. ^ Baumgart, Don. Pressure Builds to End Hydraulic Gold Mining. California Gold Rush Stories. Nevada County Gold. Retrieved on 2006-05-10.
  2. ^ Golden Gamble in Grass Valley. YubaNet.com. Retrieved on 2006-05-14.
  3. ^ The Environmental Impact of Submarine Tailings Disposal At The Island Copper Mine on Vancouver Island: A Case History In Environmental Policy (pdf). Retrieved on 2006-05-11.
  4. ^ Manado Declaration on Submarine Tailings Disposal. Mines and Communities (2001-04-30). Retrieved on 2006-05-11.
  5. ^ New York Times/Frontline Series on Gold Mining. Newmont Mining. Retrieved on 2006-05-11.
  6. ^ Buyat Bay Facts. Retrieved on 2006-05-11.
  7. ^ ICMM preliminary comments on the draft Framework for Responsible Mining (pdf). ICMM (16 June 2003). Retrieved on 2006-05-11.