Sulfate-Resistant Portland Cement from Lime-Soda Sinter Process Residue

A by-product (residue) from the Ames Lime-Soda Sinter Process for recovering alumina from power plant fly ash consists largely of dicalcium silicate and can be used as a raw material for the manufacture of sulfate-resistant (Type V) portland cement. Utilization of the residue will eliminate the need for its disposal and will improve the economic feasibility of the lime-soda sinter process. Laboratory burnability tests were used to identify optimum cement mixes and burning temperatures from both clinker quality and economic perspectives. At a typical kiln temperature of 1450°C, cements that formed concrete that exceeded ASTM specifications for strength were obtained for a limited range of lime-saturation factors and silica ratios. A highly conservative cost estimate for a combined alumina recovery and cement manufacturing facility for a 1000 MWe coal-fired power station gave a 4.7% internal rate of return.