Cement for the manufacture of cores and moulds and method for preparing same

Abstract

The cement of the invention comprises chemically combined oxides, percent by mass: CaO, 50 to 60; Al.sub.2 O.sub.3, 28 to 37; Fe.sub.2 O.sub.3, 0.01 to 1; SiO.sub.2, 0.1 to 8; Na.sub.2 O, 0.1 to 1; K.sub.2 O, 0.1 to 0.5; H.sub.2 O, 3 to 12; and incorporates 85 to 99% by mass of a fraction with a particle size of below 80 .mu.m and 1 to 15% by mass of a fraction with a particle size of from 80 to 200 .mu.m. The cement can also contain one or more additives: calcium oxide or calcium hydroxide, calcium carbonate, calcium carboaluminate. The method according to the invention for preparing said cement comprises a heat-treatment of calcium hydroalumosilicate containing SiO.sub.2 in an amount of not more than 8% by mass at a temperature of from 250.degree. to 600.degree. C. The heat-treated product is disintegrated to produce 85 to 99% by mass of a fraction with a particle size of below 80 .mu.m and 1 to 15% of a fraction with a particle size of from 80 to 200 .mu.m. During the heat-treatment of the hydroalumosilicate at least one component can be added calcium oxide or calcium hydroxide, calcium carbonate, calcium carboaluminate. The cement is useful in foundry engineering for the manufacture of articles from ferrous and non-ferrous metals.

Dependencies are inferred from the claim text.