Alternative Raw Materials and Impacts on the Cement Manufacturing Process and Regulated Air Emissions

Abstract

The cement kiln-feed mix generally consists of a combination of calcium, silica, alumina, and iron derived from a selection of traditional raw materials (e.g., limestone, clay, sand, mill scale) to form viable clinker. In efforts to increase sustainability and maximize resource efficiency, waste materials and by-products from other industries are utilized as valuable alternative raw materials to satisfy the chemistry of this blend. Alternative raw materials contain so-called impurities and may have a chemical composition varying from traditional raw materials. Presented is a discussion of commonly used alternative raw materials, as well as potential novel sources and impacts on operation of the kiln system and air emissions, with a focus on the preheater/precalciner kiln type.