GB573939A - An improved manufacture of refractories - Google Patents

Abstract

The bonded strength at intermediate temperatures of basic refractories containing magnesia or chromite is increased by adding less than 5 per cent of an element of the right hand column or groups V and VI of the periodic table and having an atomic weight between those of sulphur and tellurium, or a compound of one of these elements with another element other than iron or an alkali metal. The material is preferably water insoluble and nonreactive towards the temporary bonds such as calcium chloride, waste sulphite liquor, dextrin &c. used to facilitate moulding; it should also be sufficiently volatile to be removed at high temperatures. Sulphur, arsenic, tellurium, antimony, tellurides, arsenides, antimony oxide, or insoluble sulphides of metals such as copper, lead, or antimony can be used. The amount of material to be added varies from 0.1 to 3 per cent, and results in a reduction of the firing-temperature. According to examples: (a) bricks are made by mixing periclase, chrome ore, and 1/2 per cent sulphur, tempering with calcium chloride solution, and heating for four hours in a moist atmosphere at 300 DEG F., and then for four hours in a dry atmosphere at 350 DEG F.; (b) a periclase clinker is mixed with 1 per cent antimony oxide, tempered with sodium silicate, rammed into place in a subhearth and heated to 2400 DEG F.; (c) 1/2 per cent of antimony oxide is mixed with chrome ore, the mixture tempered with sodium silicate, pressed into brick, dried, and used without prefiring. Furnaces may be constructed with material containing the bonding agent placed adjacent material not containing the bonding agent. According to the Specification as open to inspection under Sect. 91, iron sulphide or an insoluble organic sulphide may be used. This subject-matter does not appear in the Specification as accepted.