Coal combustion wastes beneficiation

Groppo, J., Robl. T., James, C. Hower, J. C. 2004. The beneficiation of coal combustion ash. In Giere, R. Stille, P. (eds) Energy, Waste, and the Environment a Geochemical Perspective. Geological Society, London, Special Publications, 236, 247-262. 

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. 

Spontaneous combustion may develop due to the heating of coal particles and slow combustion. Toxic material may be released with the oxidation of compounds present in the waste material. Runoffs, with minimal iron pyrites content, from the tip surface, promote hazards and the acid compounds may leach into domestic water supplies. All these effects may be partly or wholly overcome with proper management of the planning and design of waste heaps and good operating practices. Moreover, encouragement of the commercial use of waste material is beneficial. 

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