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Environmental impacts of mine waste sandfill.

Levens RL; Boldt CMK
Spokane, WA: U.S. Department of the Interior, Bureau of Mines, RI 9493, 1994 Jan; :1-12
Placement of mine waste backfill in underground openings is considered underground injection under the provisions of the program. A major issue is whether mine waste that is regulated as a contaminant source on the surface should be disposed of underground. The purpose of the U.S. Bureau of Mines research discussed here is to investigate the impacts of mine waste sandfill on the quality of ground water. Analyses of water samples collected before and after contact with sandfill in a 10-year-old stope, as well as samples of the sandfill itself, were used to ascertain the influence of the sandfill after mine closure and subsequent flooding. Computer models supported the hypothesis that oxidation of pyrite by oxygen, accompanied by dissolution of carbonates, was the predominant reaction controlling the quality of the water being discharged from the stope. The water has a near-neutral pH because acid produced during oxidation of pyrite is buffered by dissolution of the carbonates. Probably most important, concentrations of metals released as a result of acid production in the test stope remained near or below detection limits. Metals release after mine flooding is expected to remain low as a result of the buffering by the sandfill and the reduced rate of oxidation.
Earth-fills; Backfills; Leaching; Tailings; Sands; Sulfides; Ground-water-recharge; Assaying; Chemical-analysis; Mathematical-models; Oxidation; Pyrite; Water-influx; Reaction-kinetics; Ions; Mining; Waste-disposal; Spoil; Water-pollution-control
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Spokane, WA: U.S. Department of the Interior, Bureau of Mines, RI 9493
Page last reviewed: May 11, 2023
Content source: National Institute for Occupational Safety and Health Education and Information Division