THE RECOVERY OF COBALT FROM BAJA MINING CORP'S EL BOLEO PROJECT

摘要

The Boleo Copper-Cobalt-Zinc-Manganese Project of Baja Mining Corp. is situated adjacent to Santa Rosalia on the Baja Peninsula of Mexico. The El Boleo ore is a mixed oxide-sulfide deposit with major values in copper, cobalt, zinc and manganese. The metallurgical process designed to treat the El Boleo orebody involves a sulfuric acid leach in seawater using oxidative and then reductive leaching to maximize metal extraction. The leach solution is separated from the barren solids via counter current washing through a series of high rate thickeners. Copper is recovered to cathode using conventional SX-EW processing. Zinc and cobalt are extracted from a portion of the copper SX raffinate after iron and aluminum precipitation. The CSIRO DSX solvent system (Versatic~R 10 and LIX~R 63 mixture) are used in this extraction. Manganese remains in the DSX raffinate and is recovered by soda ash addition as a high quality manganese carbonate precipitate. Zinc and cobalt are acid stripped from the loaded DSX solvent. Zinc is then re-extracted away from cobalt using Cyanex~R 272 extractant, stripped into a highly concentrated strip liquor (+100 g/L Zn) and directed to a granulator for production of zinc sulfate monohydrate. The zinc solvent extraction raffinate, containing cobalt, advances to a further SX circuit using Cyanex~R 272, for the recovery of cobalt as cobalt cathode. In this paper, the detailed results from bench and integrated pilot plant testing for cobalt recovery from the El Boleo ore will be described. The results will highlight the use of solvent extraction and specialty ion exchange resins to recover high purity cobalt electrolytic cathode. The results of this testing are currently being used to engineer the commercial plant at El Boleo.