Recovery of cobalt and manganese from nickel laterite leach solutions containing chloride by solvent extraction using Cyphos IL 101

An ionic liquid reagent Cyphos IL 101 (trihexyltetradecylphosphonium chloride) was studied for the recovery of cobalt and manganese from the synthetic nickel laterite leach solution containing chloride. It is shown that cobalt and manganese were effectively extracted from the solution containing 100 g/L Cl with 0.5 M Cyphos IL 101 in the pH range of 1.2-4.5, while no significant nickel, magnesium and calcium were extracted. This could lead to a simple and economical recovery of cobalt and manganese from nickel literate leach solutions. For comparison, tests with other reagents including Aliquat 336 (trioctylmethylammonium chloride) and Alamine 336 (tri-octyl (decyl) amine) which have similar molecular structures were also carried out and it was indicated that Cyphos IL 101 was advantageous for its higher extraction of cobalt and manganese. The effect of pH, chloride concentration, organic concentration and A/O ratio on the metal extraction was studied. Metal stripping tests showed that cobalt and manganese were readily stripped using water. Zinc stripping was very difficult with water and it was only achieved from a low Cyphos IL 101 concentration or using ammonia as the strip reagent. A process for the recovery of cobalt and manganese from laterite leach solutions containing chloride using Cyphos IL 101 has been proposed.