GB1473908A - Casting molten metals - Google Patents

Abstract

1473908 Casting processes FOSECO INTERNATIONAL Ltd 5 Sept 1975 [9 Sept 1974] 39331/74 Heading B3F A method of casting molten metal to form an ingot comprises locating in an ingot mould a substantially vertical tube 1 of fibrous material of melting point less than the casting temperature of the molten metal and which, under the action of the heat of the molten metal, forms a casting flux and mould wall coating, locating at or near one end of the tube a collar 2 of material which, under the action of the heat of the molten metal, disintegrates to form a cover of antipiping compound over the exposed molten metal surface at the termination of teeming, teeming molten metal into the mould to melt the tube and disintegrate the collar to form the cover of anti-piping compound, and allowing the molten metal to solidify in the mould. The tube and collar are held together by metal clips and the collar has location clips 3 for engaging the top of the walls of the ingot mould. In use, the molten metal may be top or bottom poured and, if top poured, is teemed through the tube to prevent splashing. The tube melts as the molten metal surface rises and forms the casting flux and mould wall coating and may consist of calcium or aluminium silicate fibres or glass fibres or impure materials such as rock or slag wool. The tube may be filled or bonded fibre and contain ingredients to enhance fluxing, generate a non-oxidising atmosphere, effect a fluidising of metallic oxides and aid the formation of a heat insulating layer on the top of the metal surface at the completion of turning. The collar 2 disintegrates on contact with the molten metal to form a layer of anti-piping material and consists of a heat-insulating refractory material, a heat-expandable material, such as expandable graphite, a fibrous material and a binding agent. In one example, the tube comprises, by weight, 10-60% calcium silicate fibre, 10-60% blast furnace slag, 5-20% fluorspar, 1-5% organic fibre and 4-7% binder, and the collar comprises, by weight 71% aluminium containing refractory materials, 3% oxidisable metal, 3% oxidising agent, 5% expandable graphite, 12% inorganic fibrous material, and 6% binding agent. The underside of the collar may have a heatreflective layer to prevent premature disintegration.