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Abstract

A process is disclosed for regenerating an aqueous acid halide leachant from a spent aqueous metal halide leach liquor. The process comprises introducing into a fluidized bed or spray roaster a hydrocarbon fuel, an oxygen-enriched oxidizing gas and the aqueous metal halide leach liquor; pyrohydrolyzing the aqueous metal halide leach liquor by combustion of the hydrocarbon fuel with the oxygen-enriched oxidizing gas to produce an acid halide-containing gas fraction and a metal oxide-containing solid fraction; separating the gas fraction from the solid fraction, recovering heat energy from the acid halide-containing gas fraction and absorbing the gas fraction in water to produce the aqueous acid halide leachant. The oxygen-enriched oxidizing gas has an oxygen concentration of greater than about 21 percent by volume, preferably greater than about 50 percent by volume, more preferably greater than about 80 percent by volume, and even more preferably greater than about 90 percent by volume. Preferably, the aqueous metal halide is iron (II) chloride or nickel chloride. Despite higher costs associated with the oxygen-enriched oxidizing gas as compared to air, the process is capable of being operated more economically and efficiently than an equivalent air roasting pyrohydrolysis, and produces a higher concentration aqueous halide leach liquor, which is preferred in metallurgical processes such as solvent extraction and solids leaching.

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First Claim