GB425702A - Methods of and means for preparing refractories and refractory masses so produced - Google Patents

Abstract

A ceramic mass adapted to be shaped and sintered to form a refractory consists of highly refractory materials in admixture with ignited zeolites or alternatively with ingredients adapted to react to form zeolites on heating. In the latter case the mass may first be heated below the sintering temperature. The zeolites employed are those corresponding to the formula X mol. SiO2, 1 mol. Al2O3, 1 mol. MeO, Y mol H2O, where MeO signifies the oxide of an alkali or alkaline earth metal, X is a definite whole number not greater than 5, and Y a number not necessarily whole. SiO2 may be replaced by equivalent amounts of TiO2, and Al2O3 by equivalent amounts of Fe2O3 or Cr2O3. The proportion of zeolite present should be between 3 and 20 per cent. In an example 5 parts of magnesium chabazite, produced from naturally occurring sodium chabazite by base exchange, are sintered with 95 parts of corundum. In another example kaolin is melted with quartz and alkali or alkaline earth metal carbonate to form a glass which is broken into granules and treated with water to extract sodium silicate, the residue forming zeolite by absorption of water. This is lightly calcined, and 8 parts are mixed with 92 of corundum and sintered. In another example 62 parts of chalk are fused with 38 parts of aluminium oxide; 5 parts of the resulting glass are mixed with 85 parts of corundum, 2,2 parts of lithium carbonate and 7,8 parts of Shetland kaolin and sintered, the ingredients forming a zeolite which bonds the corundum.