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Abstract

A process and apparatus for melting metals that react rapidly with air at elevated temperatures to form a stable metal oxide and/or that contains a metal oxide prior to being exposed to elevated temperature, while reducing metal losses due to oxidation or the presence of the oxides. The process involves melting the metal in the presence of a molten metal salt metal salt mixture while electrolyzing metal oxide contained in the salt metal salt mixture to convert the oxide to elemental metal. The process requires an metal salt mixture which contains at least 25% by weight, and more preferably 100% by weight, of metal fluoride and which, for the metal being melted, has a composition which remains substantially unchanged during the electrolysis process. The fluoride improves oxide solubility in the metal salt mixture, making it possible to increase current densities without producing anode effects. The stable composition makes it possible to use the metal salt mixture for prolonged periods without change. The apparatus consists of a single vessel having an interior volume divided at least into a melting zone and an electrolysis zone by a heat-resistant partition which allows the metal salt mixture to be recirculated between those zones. The process and apparatus can be used for melting metals, metal matrix composites reinforced by metal oxides and metal foams stabilized by metal oxide particles.

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