Potential use of coal ash in the Israel cement industry

Abstract Clinker raw material mixtures made from the combination of three different coal ashes with clays and carbonates were studied for their chemical and mineralogical characteristics on calcination. Using different combinations of ash with other raw materials, it was possible to produce a mixture with the desirable chemical composition similar to that produced by the ordinary clay-carbonate mixtures. After heating, both mixtures yielded clinkers with the desirable mineralogical assemblages. However, it was also found that the presence of refractory phases in the ash slowed the crystallization of clinker minerals, by not releasing silica and alumina for reactions. This kinetic influence was found to be of relatively small magnitude and does not defract from the desirability of using coal ash as an additive raw material in cement manufacture.