Coal combustion wastes trace elements

Hopkins WA, Mendonca MT, Rowe CL, et al. 1998. Elevated trace element concentrations in southern toads, Bufo terrestris, exposed to coal combustion waste. Arch Environ Contam Toxicol 35 325-329. 

Donahoe, R. J. (2004). Secondary Mineral Formation in Coal Combustion Byproduct Disposal Facilities Implications for Trace Element Sequestration. In Giere, R. Stille, P. (eds) Energy, Waste, and the Environment a Geochemical Perspective. Geological Society, London, Special Publications, 236, 641-658. 

Utilization. For example, Be and the chalcophile elements, As, Cd, Hg, Pb, and Se, which are released during coal combustion or leached from coal waste products, can present significant environmental hazards halogens such as Cl and F can cause severe boiler corrosion and volatilized Ni, Ti, or V can cause corrosion and pitting of metal surfaces. On the positive side, some trace elements (e.g., Ge, Zn, U, and Au) may eventually prove to be economic by-products of coal utilization, while other elements (e.g., B) may be useful in helping to understand depositional environments and to correlate coal seams (7.8). 

More than 40 trace elements are routinely found in atmospheric particulate matter samples. These elements arise from dozens of different sources including combustion of coal, oil, wood burning, steel furnaces, boilers, smelters, dust, waste incineration, and break wear. Depending on their sources, these elements can be found in either the fine or the... 

Many of the elements that cause concern are trapped within the fly ash after coal combustion and sometimes in the bottom ash by-products. Coal beneficiation processes prior to utilization may serve as a means of reducing the levels of at least some trace elements. Elements of concern that occur at significant levels in the processing residues may give rise to waste disposal or control problems such as leaching into the natural environment via ground or surface water infiltration. 

Mercury is one of a number of toxic heavy metals that occur in trace amounts in fossil fuels, particularly coal, and are also present in waste materials. During the combustion of fuels or wastes in power plants and utility boilers, these metals can be released to the atmosphere unless remedial action is taken. Emissions from municipal waste incinerators can substantially add to the environmental audit of heavy metals, since domestic and industrial waste often contains many sources of heavy metals. Mercury vapor is particularly difficult to capture from combustion gas streams due to its volatility. Some processes under study for the removal of mercury from flue gas streams are based upon the injection of finely ground activated carbon. The efficiency of mercury sorption depends upon the mercury speciation and the gas temperature. The capture of elemental mercury can be enhanced by impregnating the activated carbon with sulfur, with the formation of less volatile mercuric sulfide [37] this technique has been applied to the removal of mercury from natural gas streams. One of the principal difficulties in removing Hg from flue gas streams is that the extent of adsorption is very low at the temperatures typically encountered, and it is often impractical to consider cooling these large volumes of gas. 

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