Abstract: This invention relates to refining platinum group metal concentrates and the separation therefrom of silver and of the majority of base metals with which they naturally occur. In more detail the process comprises the steps of:(a) contacting a solid particulate mixture of base, silver and precious metal components, any of which components may be in metallic or chemically combined form, with a halogen-containing gas at a temperature which is sufficiently high for the base metal and silver components to form their halides and for the said halides substantially to volatilize from the said solid mixture, and(b) removing the said volatilized halides from the solid precious metal-containing component which remains.

Abstract: This invention relates to an improvement in the well known "Bayer" process. In particular, the invention describes a process for the recovery of gallium and alumina from bauxite including the steps of:A. dissolving the ore in caustic soda solution under pressure;B. precipitation of pure alumina from the remaining caustic soda solution by reduction of temperature and pressure;C. subjecting the resulting mother liquor from (b) to an elevated temperature of 60.degree. to 450.degree. C and a pressure of 2 to 100 atmos. in the presence of an oxygen-containing atmosphere; andD. cementation of the gallium remaining in solution by contact with metallic aluminium.Step (a) is preferably carried out at a pressure of 5 atmospheres and step (c) is carried out in the presence of an atmosphere consisting substantially of oxygen at a pressure within the range 20 to 50 atmospheres and a temperature within the range 150.degree. to 350.degree. C.

Abstract: This invention relates to a process for the separation of palladium present in aqueous solutions which also contain the salts of one or more of the platinum group metals platinum, rhodium, ruthenium, osmium and iridium. According to one embodiment of the invention the process comprises the steps of:A. adjusting, as necessary, the pH of the platinum group metal-containing solution to render the solution acidic;B. contacting the so-obtained acidic solution with an oxime solvent; andC. removing from contact with the acidic solution the organic phase containing substantially all of the palladium present in association with the oxime solvent.

Abstract: This invention relates to catalysts for use in the control of atmospheric pollution. The catalysts of the present invention are especially useful in the purification of exhaust gases from internal combustion engines and comprise oxidised ruthenium or ruthenium dioxide and a base metal oxide which forms a stable mixed metal oxide with ruthenium dioxide. The base metal may be selected from Groups IV and V of the Periodic Table.