Mines drainage

Because gravity is too weak to be used for removal of cakes in a gravity side filter (2), continuously operated gravity side filters are not practicable but an intermittent flow system is feasible in this arrangement the cake is first formed in a conventional way and the feed is then stopped to allow gravity removal of the cake. A system of pressure filtration of particles from 2.5 to 5 p.m in size, in neutralized acid mine drainage water, has been described (21). The filtration was in vertical permeable hoses, and a pressure shock associated with relaxing the hose pressure was used to aid the cake removal. 

PermeOx is also used to improve the bioremediation of soils contaminated with creosote or kerosene (see Bioremediation (Supplement)), to deodori2e sewage sludges and wastewater (see Odormodification), and to dechloriaate wastewater and effluents. A special formulation of calcium peroxide, made by FMC and sold ia the United States under the trademark Trap2ene, is used for removing metal ions from acidic waste streams such as coal ash leachate and acid mine drainage (see Wastes, industrial). 

Air or biological oxidation of pyrite leads to sulfate formation and dilute sulfuric acid in the mine drainage. This pollutes streams and the water supphes into which the mine water is drained. Means of controlling this problem are under study. 

Self-Test L.3B Many abandoned mines have exposed nearby communities to the problem of acid mine drainage. Certain minerals, such as pyrite (FeS,), decompose when exposed to air, forming solutions of sulfuric acid. The acidic mine water then drains into lakes and creeks, killing fish and other animals. At a mine in Colorado, a 16.45-mL sample of mine water was completely neutralized with 25.00 mL of 0.255 M KOH(aq). What is the molar concentration of H2S04 in the water ... 

As we saw in Section L, titration involves the addition of a solution, called the titrant, from a buret to a flask containing the sample, called the analyte. For example, if an environmental chemist is monitoring acid mine drainage and needs to know the concentration of acid in the water, a sample of the effluent from the mine would be the analyte and a solution of base of known concentration would be the titrant. At the stoichiometric point, the amount of OH " (or 11,0 ) added as titrant is equal to the amount of H30+ (or OH-) initially present in the analyte. The success of the technique depends on our ability to detect this point. We use the techniques in this chapter to identify the roles of different species in determining the pH and to select the appropriate indicator for a titration. 

Nyquist, J. and Greger, M., A field study of constructed wetlands for preventing and treating acid mine drainage, Ecological Engineering, 35 (5), 630-642, 2009. 

Davison, J., The lambda process - for desulfurization of slurry coal fines prior to combustion, in Eighth Annual Surface Mine Drainage Task Force Symposium. 1987. Morgantown, West Virginia, April 7-8. 

Turner, A., Rawling, M.C. (2002) Sorption of benzo[a]pyrene to sediment contaminated by acid mine drainage contrasting particle concentration-dependencies in river water and seawater. Water Res. 36, 2011-2019. 

There are, fortunately, some instances in which measured Eh values can be interpreted in a quantitative sense. Nordstrom et al. (1979), for example, showed that Eh measurements in acid mine drainage accurately reflect the aFe+++/aFe++ ratio. They further noted a number of other studies establishing agreement between measured and Nernst Eh values for various couples. Nonetheless, it is clearly... 

Sorption can significantly diminish the mobility of certain dissolved components in solution, especially those present in minor amounts. Sorption, for example, may retard the spread of radionuclides near a radioactive waste repository or the migration of contaminants away from a polluting landfill (see Chapters 21 and 32). In acid mine drainages, ferric oxide sorbs heavy metals from surface water, helping limit their downstream movement (see Chapter 31). A geochemical model useful in investigating such cases must provide an accurate assessment of the effects of surface reactions. 

The above reaction represents, in a simplified way, the origin of acid mine drainage. Streambeds in areas of acid drainage characteristically become coated with an orange layer of ferric precipitate. We can write a reaction representing the overall process by swapping ferric hydroxide in place of the ferrous ion ... 

Chapman, B. M., D. R. Jones and R. F. Jung, 1983, Processes controlling metal ion attenuation in acid mine drainage streams. Geochimica et Cosmochimica Acta 47,1957-1973. 

Davis, A., R. L. Olsen and D.R. Walker, 1991, Distribution of metals between water and entrained sediment in streams impacted by acid mine drainage, Clear Creek, Colorado, U.S.A. Applied Geochemistry 6, 333-348. 

Ficklin, W. H., G. S. Plumlee, K. S. Smith and J. B. McHugh, 1992, Geochemical classification of mine drainages and natural drainages in mineralized areas. In Y. K. Kharaka and A. S. Maest (eds.), Water-Rock Interaction. Balkema, Rotterdam, pp. 381-384. 

Johnson, C. A., 1986, The regulation of trace element concentrations in river and estuarine waters with acid mine drainage, the adsorption of Cu and Zn on amorphous Fe oxyhydroxides. Geochimica et Cosmochimica Acta 50, 2433-2438. 

Mayo, A. L., P. J. Nielsen, M. Loucks and W. H. Brimhall, 1992, The use of solute and isotopic chemistry to identify flow patterns and factors which limit acid mine drainage in the Wasatch Range, Utah. Ground Water 30, 243-249. 

Taylor, B.E., M. C. Wheeler and D.K. Nordstrom, 1984, Isotope composition of sulphate in acid mine drainage as measure of bacterial oxidation. Nature 308, 538-541. 

Otters (Lutra lutra) were found only on a single unpolluted tributary of a river system contaminated by zinc mine drainage waste, suggesting that a contaminated food supply may be responsible for avoiding otherwise suitable habitat (Mason and Macdonald 1988). 

Mason, C.F. and S.M. Macdonald. 1988. Metal contamination in mosses and otter distribution in a rural Welsh river receiving mine drainage. Chemosphere 17 1159-1166. 

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