PROCESS FOR THE PURIFICATION OF IRON OXIDES

1,242,043. Purification of Iron oxides. Y-P.P. MAYOR, and P. F. TORD. 3 Jan., 1969 [3 Jan.,1968], No.573/69. Addition to 1,203,967. Heading C1A. Iron oxides obtained by the roasting of ores, in particular the roasting of sulphide ores in air are purified by contacting the ashes resulting from roasting, which ashes contain non-ferrous metal oxides and SiO 2 as impurities, in a reaction zone with a hot carrier gas and at least one hydrohalic gas at a temperature sufficient to vaporize the halides formed from the non- ferrous metal oxides and lead to their entrainment by the carrier gas wherein water vapour is present in the reaction zone to enhance the formation of non-ferrous metal halides while inhibiting the formation of iron halides and wherein as a hydrohalic gas precursor an aqueous solution of an iron halide salt is introduced into the reaction zone, thus providing the hydrohalic gas in situ and the necessary water vapour for the reaction. The iron halide salt is used in an amount between 105-150% of the stoichiometric amount required to convert the non-ferrous metals into their halides. These halides are condensed from the carrier gas by cooling and cemented with metallic iron, and the iron halide solution thus obtained is recycled.