process for the production hydratisierter calcium silicate products

摘要

Hydrated calcium silicate defined below, is reacted with aluminium sulphate at at least 350 DEG F., preferably between 450 DEG F. and 550 DEG F. in an amount equivalent to and for a period sufficient to effect reaction with at least 5%, preferably 7 1/2 % to 60% by weight of the total CaO component of the hydrated calcium silicates. The product is particulate. The initial silicate is the hydrothermal reaction product formed from an aqueous suspension of lime and a reactive siliceous material at 350 DEG F. at least. Siliceous materials may be quartz, diatomaceous earth, or preferably, xontolite, or a synthetic composition of formula:-2CaO.3SiO2.1-2.5H2O. It is preferred to carry out the reaction in aqueous medium and the reaction according to the invention may be performed in the same reaction vessel after forming the calcium silicate by adding the necessary aluminium sulphate, and setting up the essential temperature conditions. In the examples the formation of the calcium silicate and immediate alum after treatment are described and comparative data is presented on the effect of alum treatment at various levels on high temperature calcium silicates, as well as a low temperature calcium silicate, which latter is outside the scope of the invention.