GB624479A - Improvements in or relating to treatment of molten metals and molten alloys - Google Patents

Abstract

A process for degassing molten metals, such as aluminium, magnesium and their alloys, consists in placing on the molten metal a tablet formed by compression of an organic bromine or iodine compound so as to have a higher specific gravity than the molten metal with which it is used. The compound used may be tetrabromethane, hexabromethane, carbon tetraiodide or hexaiodoethane. Two or more of these compounds may be used in combination. The tablet may include one or more of the following, namely: an amount of barium chloride sufficient to ensure that the specific gravity of the tablet is such that it will sink in the molten metal, an amount of grain refining agent which will leave a residue of lower specific gravity than the metal so that the residue will rise to the surface of the metal to permit of its ready removal, the amount of grain refining agent being insufficient to reduce the specific gravity of the tablet below that of the molten metal. The degassing agent may consist of hexachlorethane with a chemical product, non injurious to the molten metal, and in such amount as to increase the specific gravity of the tablet to above that of the molten metal, e.g. at least 50 per cent of copper. The said chemical product should have no injurious effect on the metal treated and when used with magnesium or magnesium alloys the resulting tablet should have a specific gravity not less than 2-0. Thus not more than 20 per cent of barium chloride or barium carbonate may be included in a tablet with hexachlorethane.