Mine waste tailings

A primary human health concern associated with mine wastes, tailings, and smelting byproducts produced during the extraction of metals from metallic mineral deposits has been the incidental ingestion exposure, and resulting heavy metal uptake, especially for small children who play on waste piles, tailings, slag heaps, or... 

Mine wastes, tailings, and smelter slag and emissions can contain complex mixtures of minerals that are typically a predictable function of the geologic characteristics of the deposit type being mined, coupled with the ambient climate/ environmental characteristics and the mining or mineral processing method used. See Chapter 9.05 and Plumlee (1999) for a detailed discussion. 

Soils that have been contaminated by mine wastes, tailings, smelter slags, or smelter particulates can contain a complex mixture of minerals present in the soils prior to contamination minerals contributed by the contaminants minerals formed by soil weathering, biological reactions, and chemical reactions with infiltrating waters and soil moisture windblown dust, and other anthropogenic materials (Ruby et al, 1999). For example, reactions of lead oxide with soil moisture in alkaline soils can precipitate lead carbonate, whereas reactions in acidic soils can precipitate lead sulfate. 

Hence, mine wastes, tailings, and smelting byproducts can contain a wide variety of minerals, including minerals that are bioreactive (such as acid-generating sulfides and evaporative sulfate salts), minerals that contain potentially bioaccessible heavy metals and metalloids (lead, cadmium, arsenic, mercury, zinc, copper, nickel, uranium, molybdenum, antimony, etc.), and minerals that are biodurable (such as quartz and, in some deposit types, asbestiform silicates). 

Fig. 23. Methods of tailings dam constmction (a) upstream method, (b) downstream method, and (c) mine waste rock dam constmction (6).

HydrometaHurgical processes for copper can be categorized as (/) acid extraction of copper from oxide ore (2) oxidation and solution of sulfides in waste rock from mining, concentrator tailings, or in situ ore bodies (J) dissolution of copper in concentrates to avoid conventional smelting and (4) extraction of copper from deep-sea manganese nodules. 

Populations of freshwater oligochaetes and leeches were reduced in numbers of individuals and numbers of taxa in mine tailing effluents containing 146 to 213 pg Zn/L or sediments containing >20 g Zn/kg DW (Willis 1985b). Leeches (Erpobdella octoculata) experienced a reduction in density and reproductive capacity in streams containing 25 to 310 pg Zn/L from mine wastes and did not avoid these harmful concentrations (Willis 1989). 

The highest contents of Pb and Zn in tributary sediments were measured in Helenski potok (ME-5) and Juncarjev potok (ME-14) and are interpreted as a consequence of discharge from mining waste dumps and tailings in the tributaries area. 

Al T.A., Blowes D.W., Jambor J.L., Scott J.D. 1994. The geochemistry of mine-waste pore water affected by the combined disposal of natrojarosite and base-metal sulfide tailings at Kidd Creek, Timmins, Ontario. Canadian Geotechnical Journal, 31, 502-512. 

Benzaazoua, M., Bussiere, B., Dagenais, A.M. 2001. Comparison of kinetic tests for sulfide mine tailings. In Tailings and Mine Waste "01" Fort Collins, Colorado, January. Balkema, Rotterdam, 263-272. 

Blowes, D.W., Ptacek, C.J., Jambor, J.L 2003. Mill Tailings Hydrology and Geochemistry. Environmental aspects of Mine Waste. Mineralogical Association of Canada Short Course series 31, 95-116. Etcheverry, D.J. 2009. Spatial and Temporal Variations in the Ruttan Mine Tailings, Leaf Rapids, Manitoba, Canada. M.Sc. thesis, University of Manitoba, Winnipeg, Manitoba. 

Delany, T.A., Hockley, D.E., Champman, J.T., Holl, N.C. 1998. Geochemical characterization of tailings at the McArthur River Mine, Saskatchewan. Tailings and Mine Waste 98, Balkema, Rotterdam. 

The relative area of mine solid waste tails (per 100,000 M3 of rock mass) is 0.7-0.8 of the total area. On average, the disturbed areas of uranium ore exploration site are partitioned as follows 32.3% of disturbed land is occupied by dumps, 27.2%, by pits, 20.3%, by industrial areas, 13.3%, by tails, and about 10%, by other types of land disturbance. 

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. 

In the case of mine waste comprising finer grained tailings, a theoretical approach to calculating exothermic reaction rates can be tractable, as the diffusion of 02 into the wastes may be a rate-limiting step, and a process that can be simulated by relatively straightforward models. 

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