Calculation of the raw mix proportion

After presenting a historical introduction, the author of this section deals in detail with the cement raw materials, their suitability and the calculation of the raw mix proportions. The chemical, mineralogical and physical processes associated with burning the materials in the kiln are described. 

The first step, in conjunction with planning the quarrying operations, consists in determining the average chemical composition. Then follows the calculation of the raw mix composition. With the results of this calculation the proportion of limestone from the first quarry block required in the mix can be determined. Once this value has been determined, the precise working life of the block can be calculated. 

For deciding on the suitability of raw materials it is furthermore essential to perform mix proportioning calculations in order to ascertain the content of alkalies, sulphates, chlorides and MgO introduced into the raw mix. 

The calculation of raw mix proportions is useful in connection with the planning of new cement works or the opening-up of new raw material deposits in that it provides approximate guidance on the quantities of materials required and on the suitability of the available raw material components. On the other hand, such calculations are of dubious value for routine production purposes, because in practice the respective components are continually subject to more or less substantial variations. This would necessitate regular analytical monitoring of the raw materials and, on the basis of the results, continual recalculation of the mix proportions. 

---