Separation of Nickel and Zinc from a mixture of their Salts: Part I - Chlorination of mixtures of Nickel and Zinc oxides

Abstract

Mixed oxides of nickel and zinc will be available as a bye-product from the silver refinery under construction at Calcutta. The paper is concerned with possibilities of separating zinc from the mixture of oxides by passing HCl gas at elevated temperatures. Zinc oxide can for example, be completely removed from a mixture containing 5 percent zinc oxide and 95 percent nickel oxide by hydrochloride acid treatment at 1000° c. The frequency changes for the reactions of the oxides with the HCl gas at elevated temperatures have been calculated from thermodynamic data and it is shown that, at 1000° c, only the zinc oxide should react. It has however been found that when a mixture containing equal amounts of nickel and zinc oxide is treated with hydrogen chloride gas at 1000° to 1100°c, 20-25 percent of zinc oxide is also chlorinated along with 97-98 percent of zinc oxide. Possible reasons for the chlorination of nickel oxide at 1000° c have been discussed and remedial measures to overcome the difficulties pointed out. Further work is in progress.