Use of mineral coal ashes in insulating refractory brick

Abstract

Coal ash from Candiota thermoelectric power plant in southern Brazil is a waste generated in great amount. Current estimates indicate that coal ash production is likely to reach 2.000.000 tons per year. Of this total, only 10% are commercialized, so the price of this material is very low. In this work, it was investigated the use of coal ashes in a composition of refractory insulating brick. In coal combustion process, fly ashes and bottom ashes are generated. Bottom ashes are formed by partially fused ashes that precipitate to the bottom of the boiler, due to their coarser particle size. Therefore, it was analyzed fly ash addition in a refractory body and the addition of bottom ashes, partially replacing chamote (calcinated clay). The results showed that the effect of the ash is small in the fired materials. In terms of technological characterization, the bricks formulates with coal ash were considered suitable to commercial brick standards. Density and thermal conductivity of the refractory bricks with coal ashes had revealed to be similar the commercial products. Then, the use of ash is economical attractive and technical feasible.