COAL ASH AS AN ORE: GEO-TECHNICAL METHODS FOR COAL COMBUSTION ASH EXPLORATION AND UTILIZATION

Coal combustion by-products (unburned carbon, fly-ash and bottom ash) produced by coal-fired power plants are typically stored in ponds and permitted landfills. When the storage facility fills to capacity it is necessary to haul material off site for disposal, construct a new storage facility, or find a use for some of the material. Beneficial re-use is only possible if the ash meets the necessary quality criteria. Some current uses for ash include construction fill, lightweight aggregate for concrete masonry, and direct replacement for Portland cement in concrete.

The University of Kentucky Center for Applied Energy Research (CAER) in conjunction with Western Kentucky Energy (WKE) and the US Department of Energy are constructing an ash beneficiation plant to recover high quality fuel and lightweight aggregate from the ash ponds at WKE's Coleman Station in Hawesville, KY. The high quality fuel will be re-burned at Coleman Station while the lightweight aggregate will be utilized in the local cement block market. Plant design will be based on the results of an extensive exploration program that will involve unique drill core and mapping activities analogous to those used in mineral exploitation. The ash processing plant incorporates hydraulic classification, gravimetric concentration, and froth flotation. Successful implementation of this technology will ultimately reduce the amount of ash in the ponds at Coleman Station while curbing disposal costs and long-term environmental liabilities.