Removal of impurities from nickel oxide granules

Granular NiO, produced by roasting crude NiS material over its softening temperature and containing as impurities Cu, Pb, As and/or previous metals, is purified by heating to at least 2000 DEG F. while selectively chlorinating and volatilizing the impurities by means of a chlorine-containing gas mixture non-reducing to NiO. Preferably, the granular NiO is in the form of a fluidized bed and chlorine (in amount 0.5 to 7% by wt. of the NiO) is fed to the bed in admixture with a fluidizing gas, e.g. air. Heating may be effected by combustion of fuel in the bed which is so controlled that the gas mixture contains less than 5% by vol. free O2 and less than 15% by vol. water vapour.