ABSTRACT
It has already been stated in Chapter 1 that two generically different natural raw materials—calcium carbonate (limestone) and aluminum silicate (clay, shale, etc.)—are basically required to produce the Portland cement clinker. These two raw materials complement each other in stoichiometric proportions to give rise to the compounds or phases present in the clinker in the required quantities. At times, when such stoichiometric needs are not met by the above two primary components, certain corrective materials such as bauxite, laterite, iron ore or blue dust, sand or sandstone, etc. are used to compensate the specific chemical shortfalls in the composition of the raw mix. Additionally, for processing advantages, certain chemicals are used as grinding aids in the milling process and as mineralizers in the burning process. For resource conservation, a large number of industrial wastes or byproducts are used as raw materials, mostly for correction purposes. The most commonly used raw materials are summarized in Table 2.1.
