Covering for molten metal and process for producing the same

Abstract

A pulverulent insulating and purifying covering (3) for the surface of liquid metal (2) contained in a metallurgical receptacle (1), comprises a layer (4) which includes at least one metallic oxide of basic character, capable of reacting with oxide inclusions contained in the liquid metal. This layer (4) covers a first layer (5) in direct contact with the liquid metal and including also at least one such metallic oxide and additionally a flux (6) in a quantity sufficient to render fluid this first layer (5) under the influence of the heat of the liquid metal (2). The metallic oxide is selected from the group consisting of lime, magnesia, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, dolomite and a mixture thereof. Each layer (4, 5) includes a mixture of lime and magnesia. The first layer (5) in contact with the liquid metal (2) includes a substantial amount up to 30% by weight of flux, while layer (4) which covers the first layer (5) is substantially free from flux. There is added, either continuously or periodically, to the first layer (5) flux sufficient to maintain the first layer in a fluid condition under the influence of the heat of the liquid metal (2). This can be done by feeding the flux through a conduit which opens below the lower surface of the second layer (4), for example by introducing the flux into a casting tube (9) through which the liquid metal (2) has been introduced into the metallurgical receptacle (1) , or by introducing the flux through both layers ( 4, 5) and into the liquid metal so that the flux rises to the underside of the first layer (5).

Dependencies are inferred from the claim text.