Separation and recovery of cobalt and nickel from sulfate solutions of Indian Ocean nodules using Cyanex 272

A process for the separation and recovery of cobalt and nickel was optimize d for a sulfate leach solution of Indian Ocean sea nodules containing 80 g/ m(3) cobalt and 730 g/m(3) nickel using the sodium salt of Cyanex 272 as th e extractant. Extraction of both cobalt and nickel increased with an increa se in equilibrium pH and extractant concentration. The extracted species wi th respect to cobalt appears to be CoA(2). 3HA. More than 99.6% extraction of cobalt was achieved using 0.04M solvent in a three-stage counter current simulation at the A:O phase ratio of 3:2. The co-extraction of nickel was about 0.6% only. Two-stage countercurrent stripping of cobalt from the load ed organic at an A:O ratio of 1:7 resulted in a pregnant electrolyte enrich ed by 0.8 kg/m(3), thus enabling a ten times overall enrichment of cobalt. From the cobalt-free raffinate, nickel extraction was carried out using 0.2 5M solvent in two countercurrent stages, and the extraction showed a 99.8% recovery. Stripping of nickel from the loaded solvent was carried out at ti n equal phase ratio with the advance electrolyte of pH 1.75 in two counterc urrent stages. The nickel stripping efficiency was found to be 98.8%. The p resent studies indicated that complete recovery of cobalt and nickel was po ssible using nine counter-current stages.