Reclamation of metals by flash direct reduction

Abstract

A high-temperature chemical reaction process is performed in which a finely-divided volatile carbonaceous reductant is intimately mixed with finely-divided transition metal compounds and introduced, in entrained flow, into a strong radiative environment, inducing preferential heating of the solids and causing gasification of the volatile carbonaceous reductant principally to carbon monoxide gas and hydrogen gas. The gases in turn reduce the metal compounds to their parent metals. Nonvolatile metals in the form of small solid spheres are readily separated from their physical mixtures with spherical inorganic slags, making the process useful for the reclamation of metals from spent catalysts and low-grade ores. Because of the heterogeneous temperature distribution in the stream, reduced volatile metals are readily distilled out of nonvolatile melts, and condense in the cooler gas component of the stream as fine powders which are easily separated from the larger nonvolatile metal and slag fractions. This property of the process is particularly useful in the reclamation of metals from electric arc furnace dust.