REFINING OF METALS

摘要

A procedure and apparatus for refining platinum group metal concentrates and the separation therefrom of silver and of the majority of base metals with which they naturally occur is provided herein. In more detail the process comprises the steps of: (a) contacting a solid particulate mixture of base, e.g. one or more of Sb, Sn, Pb, Zn, Ca, Ni, Fe, As, Se and Te. silver and precious metal components e.g. gold, ruthenium, rhodium, palladium, osmium, iridium, or platinum, any of which components may be in metallic or chemically combined form, with a halogen containing gas (e.g., hydrogen chloride, hydrogen bromide, chlorine or bromine) at a temperature which is below the melting point of the mixture but which is sufficiently high for the base metal and silver components to form their halides and for the halides substantially to volatilize from the solid mixture, and (b) removing the volatilized halides from the solid precious metal-containing component which remains. The apparatus provided herein for carrying out the process comprises: (a) a gas-tight means for feeding particulate solid into a tubular vessel constructed of a refractory material; (b) a vertical shaft reaction chamber connected to the tubular vessel and having an inlet for the introduction of halogen-containing gas and an outlet for exhaust gases including volatilized halides; (c) heating means, disposed around the shaft reaction chamber, and (d) a discharge system, whereby precious metal-containing residue may be ejected from the reaction vessel.