Hydraulic and earth engineering – Earth treatment or control – Chemical
Patent
1989-06-07
1991-02-05
Taylor, Dennis L.
Hydraulic and earth engineering
Earth treatment or control
Chemical
405 52, 405128, 210170, 210747, E02C 300
Patent
active
049900315
ABSTRACT:
Mine tailings containing iron sulphides can cause acidity in groundwater travelling down through the tailings, if the tailings ever become exposed to the air. In the worst case, if only an upper level of the tailings becomes exposed, the amount of acidity produced is as if the whole body of tailings were exposed, because ferric ions in the water seeping down from the vadose region to the still-unexposed anaerobic regions tend to cause oxidation of the sulphides below, as if they too had become exposed. A layer of organic carbon (in the form of wood chippings, seaweed, etc) is added to the body of tailings, just below the (stabilized) water table. Water seeping down from the vadose region encounters the carbon before reaching the anaerobic sulphides, and most of the oxidation-producing tendency of the ions in this water is dissipated on the carbon, by bacterial action, leaving the anaerobic sulphides below unchanged. Further layers of organic carbon may be included, below the predicted level of the water table, as a safety factor to cater for errors or accidents that might affect the water table level.
REFERENCES:
patent: 1935090 (1933-11-01), Holland
patent: 3586624 (1971-06-01), Larson
patent: 4522723 (1985-06-01), Kauffman
patent: 4624604 (1986-11-01), Wagner et al.
"A Treatment of Acid Mine Water Using Sulfate Reducing Bacteria" (Wakoo et al., Journal of Ferment. Technol., vol. 57, No. 5, pp. 445-452, 1979).
"Microbial Sulfate Reduction and its Potential Utility as an Acid Mine Water Pollution Abatement Procedure" (Tuttle et al., Applied Microbiology, vol. 17, No. 2, Feb. 1969).
"Observations on a Microbial Cellulose Degradation Process that Decreases Water Acidity" (Jongejan, International Biodeterioration, vol. 22, No. 3, 1986).
"Leaching Characteristics of Uranium Tailings from Ontario and Northern Saskatchewan" (Silver, publ. by Canada Centre for Mineral and Energy Technology, Jun. 1983).
"Aquatic Plants and Bog Covers to Prevent Acid Generation-Base Metal Tailings" (Silver, Atlantic Institute of Biotechnology, Halifax, NS).
Blowes David W.
Ptacek Carol J.
Ricci John
Taylor Dennis L.
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