GB489700A - Improvements relating to the melting and refining of magnesium and its alloys - Google Patents

Abstract

Magnesium or its alloys are refined or melted by contacting the molten metal with a flux and subsequently allowing the mixture to settle out of access of air, the flux comprising a mixture of the chlorides of magnesium, an alkaline earth metal, and an alkali metal, having a specific gravity above that of the molten metal and a wetting capacity such that the molten metal swims on the flux and with gentle movement can be covered with a film thereof which endures for only a short time after the mixture has resumed a condition of rest. The flux may comprise 15-40 per cent of magnesium chloride, 5-20 per cent of calcium chloride, 5-20 per cent of barium chloride, 0-10 per cent of sodium chloride, 0-5 per cent of calcium fluoride, and 0-5 per cent of magnesium fluoride, with the remainder potassium chloride in amount always greater than 40 per cent. In addition, fluorides of alkali-earth metals, double fluorides of aluminium and the alkali-earth metals, boracic acid, and borax may be present. In the case of refining, the metal may be melted under a known flux and transferred to a vessel where it is gently agitated or vigorously stirred with the flux. In melting, the metal may be added little by little to a heated crucible to which the flux is added from time to time, or it may be melted in a large bath of flux. In order subsequently to purify the molten metal, portions thereof are withdrawn and allowed to stand. Attack by air is prevented by the use of a protective flux or atmosphere. Specification 346,271 is referred to.