Method for manufacturing cement clinker

Abstract

The invention relates to a method for manufacturing cement clinker whereby the raw meal is initially subjected to preparatory processing, e.g. by comminution, homogenization and/or drying, and, eventually, nodulized and burned, with the nodulization process itself taking place in a stationary burning reactor. By the method according to the invention a sulphatic compound is added to the raw meal in a sufficient quantity before introducing the raw meal into the stationary burning reactor or directly into the stationary reactor, e.g. through the combustion air or together with the fuel. The sulphatic compound may be selected among all types of sulphates which will not affect the properties of the finished cement. It is particularly advantageous to use calcium sulphate, either naturally occurring or industrial by-products and regular waste materials, e.g. used absorbent from dry exhaust gas desulphurization. In order that the method according to the invention can be carried out it is preferred that the sulphate content of the calcined raw meal be considerably higher than the alkali oxide content, in accordance with the following formula (the percentages indicated are percentages by weight): %SO.sub.3 >%K.sub.2 O+1.5.multidot.%Na.sub.2 O where the SO.sub.3 percentage represents the total content of sulphate in the material streams introduced into the process.

Dependencies are inferred from the claim text.