Improvements in the manufacture of cement from blast furnace slag

摘要

546,628. Slag cements. BJORKMAN. E. B., and ESCOR INDUSTRIES, Ltd, Jan. 16,1941, N'o. 616. [Class 22] A water-setting cement comprises granulated blast furnace slag, calcium sulphate in any of its known forms, a basic or basicity-generating energizer, with or without the admixture of alkali metal sulphates and (or) carbonates, the ingredients having hard and tough particles being reduced separately to such fineness that substantially not less than 20 per cent. of the total weight of the ingredients have a maximum diameter of 10 microns, whereupon the ingredients having soft particles are mixed therewith and the mixture reground to requisite fineness. Thus the slag, or slag and Portland cement clinker, are ground in a tube mill, and reground along with ground calcium sulphate in a second mill. Specification 546,627, [Group II], is referred to.