Removal of Mo and Fe from the Cobalt Chloride Solution by Ion Exchange during the Recovery Process from Spent Hydrodesulfurization Catalysts

Abstract

During the recovery of cobalt from the chloride leaching solutions of spent hydrodesulfurization catalysts by solvent extraction with amine, a cobalt chloride solution of ∼98% purity was obtained by stripping of the loaded amine with HCl solution. The major impurity elements in this cobalt chloride solution were molybdenum and iron, whose concentration was <10 ppm. In order to remove these impurities from the solution, ion exchange experiments have been performed. For this purpose, strong cationic (Diphonix) and anionic exchange resins (AG1-x8) were tested in the pH range from zero to 4. Our results indicated that Mo and Fe were removed simultaneously by ion exchange with Diphonix from the solution with pH 1. The loading capacity of Diphonix for Mo and Fe at this pH was found to be 90 and 40 mg/g of resin. Column experiments verified that pure cobalt chloride solution with 99.97% purity was obtained by ion exchange with Diphonix.