Tailings environmental impact

The U.S. Bureau of Mines-Spokane Research Center is conducting research on the environmental impacts of placing mine wastes underground as backfill. This work includes a review of residual cyanide in placed landfill, water quality monitorings at two mines and laboratory tests of cyanide fate in underground environments and permeability/leachate effects through cemented tailings. 

DOE 1996. Final Programmatic Environmental Impact Statement for the Uranium Mill Tailings Remedial Action Ground Water Project, DOE/ EIS-0198, DOE, Washington, USA. 

Paskall (25) has recently reviewed the various modifications to the Claus process that result in optimum sulfur recovery efficiency. Overall plant conversion efficiencies in the range of 97% were considered to be the upper limit at the beginning of the 1970 s (26). While this is a very respectable conversion efficiency for an industrial process the unrecovered 3% in a 2,000 tonne/d sulfur plant represents 60 tonnes/d of sulfur lost, mainly to atmosphere as 120 tonnes/d of SO2. Modifications to the four stage Claus converter train however, can raise overall conversions to over 98.5% thus halving the sulfur loss to the plant tail gas. This either reduces environmental impact or the load on tail gas desulfurization units that will be discussed later. 

Lee, C.H. and Lee, H.K. (2004) Environmental impact and geochemistry of old tailing pile from the Sanggok mine creek, Republic of Korea. Environmental Geology, 46(6-7), 727-40. 

For an efficient absorption tower design, the plant should emit tail gases at less than 1000 ppm of nitrogen oxides. This level is about half the current emissions limit in Western Australia. Should emissions exceed this figure, then consideration must be given to the installation of a catalytic tail-gas combustor which enables emission levels to be lowered below 400 ppm. The plant does not normally produce any liquid waste streams (see Section 5.4.7 Environmental Impact Analysis). 

The other environmental impact consideration is noise. The air compressor with its tail-gas expander and steam-turbine drive could present a problem. Therefore, this unit should be enclosed in a brick building to contain the noise, with those working inside the building required to wear approved ear protection. 

Rippon, G.D. and Riley, S.J. (19960 Environmental impact assessment of tailings dispersal from a uranium mine using toxicity testing protocols, Water Resources Bulletin 32 (6), 1167-1175. 

Process design the report gives several examples of products that reduce environmental impact. It also identifies that electricity is the principal component of the air separation process, and that we constantly strive to improve the energy efficiency of our plants . Even so a no score has been awarded since only one example of a process improvement is given (changing a cleaning system to reduce ozone emissions), while at the same time the report includes a number of examples where tail-end treatment has been used to reduce emissions. 

Ahlf, W. Munawar, M. (1988) Biological assessment of environmental impact of dredged material. In Chemistry and Biology of Solid Waste - Dredged Material arid Mine Tailings, eds. W. Salomons U. FSrstner, pp. 127-142. Berlin Springer-Verlag. 

Recent advances in the development of reverse micelle and microemulsion phases in CO2 will provide an important new solvent system for reactions [12,23-33]. Although the principles are mostly the same as for conventional reverse-micelle systems, the surfactants required for CO2 must contain C02-philic tails compatible with the unique aspects of the C02-continuous phase. A C02-based microemulsion would have minimal environmental impact, since at this scale of use the solvent is environmentally benign. 

These considerations of the general behaviour of metals in aquatic and soil systems should be used to assess and control accumulation and mobilisation processes of trace metal ions. To evaluate the environmental impact of mining activities with regard to chemical contaminants, the following main steps of geochemical activities are recommended (1) estimate the extent of the local and regional contamination, (2) quantify the sources of heavy metals, chlorides, sulphates and thus the total acidity and salinity, as well as other contaminants and (3) define and control major sources, i.e. waste rock heaps, tailings, waste dumps and air pollution, etc. 

Lottermoser, B. G. 2007. Mine Wastes Characterization, Treatment, Environmental Impacts, 2nd ed. Berlin Springer. A comprehensive reference on mine wastes with chapters on sultidic mine wastes, mine water, tailings, cyanidation wastes of gold-silver ores, radioactive wastes of uranium ores, and wastes of phosphate and potash ores. This book was named an Outstanding Title in the January 2008 CHOICE review. 

Beauchemin, S. and Kwong, Y.T.J. (2006) Impact of redox conditions on arsenic mobilization from tailings in a wetland with neutral drainage. Environmental Science and Technology, 40(20), 6297-303. 

VeskaE, Eaton RS. 1991. Abandoned Rayrock uranium mill tailings in the Northwest Territories environmental conditions and radiological impact. Health Phys 60(3) 399-409. 

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