RECOVERY OF NICKEL AND COBALT DIRECTLY FROM LEACH SOLUTIONS CONTAINING IRON AND ALUMINIUM USING A NEW DSX PROCESS

摘要

Recently, a new reagent was synthesised and a new synergistic solvent (SSX) system was developed by the CSIRO SX group for a new direct solvent extraction process (DSX) to directly separate nickel and cobalt from iron and aluminium in solutions including laterite heap leach solutions (HL), atmospheric leach solutions (AL) and high pressure acid leach solutions (HPAL). The features of the new SSX system are:1. It extracts Ni and Co ahead of Fe(lll) and Al and therefore it can be used for the separation of Ni and Co from Fe(lll) and Al directly.2. It has low solubility in aqueous solutions, similar to that of commercial reagents. It is chemically stable based on the results of a 12-weeks stability study.3. Cobalt can be separated from nickel and copper by selective stripping using diluted sulphuric acid at pH range of 1.0-1.2 while nickel can be separated from copper by another selective stripping using 1 M sulphuric acid. The copper can then be partially bulk-stripped using 6 M sulphuric solution in an organic bleed stream.4. A simple DSX process flowsheet has been developed to recover nickel and cobalt from laterite leach solutions directly.5. Capital and operating costs could be largely saved with the new CSIRO DSX process.In summary, the new CSIRO DSX process is a significant technology development to separate Ni/Co from Fe/AI and other impurities with possible significant capital and operating cost savings.