Solvent extraction of Ni and Co from Ni-laterite leach solutions using a new synergistic system consisting of Versatic 10 acid, Mextral 6103H and Aliquat 336 with elemental mass balance for leaching, precipitation, solvent extraction, scrubbing and stripping

Abstract

A new synergistic extraction system containing Versatic 10 acid, Mextral 6103H and Aliquat 336 was investigated for nickel and cobalt recovery from nickel laterite leach solutions. It was found that the addition of 0.3 M Aliquat 336 could significantly improve the nickel stripping kinetics of the Versatic 10 acid and Mextral 6103H mixed system, resulting in 98.9% stripping efficiency within 2 min. The effect of Aliquat 336 on the Versatic 10 acid (V10) and Mextral 6103H mixed system in terms of extraction and stripping performance was investigated. Based on the McCabe-Thiele plots for nickel/cobalt extraction and stripping, semi-continuous tests were conducted using the employed synergistic system. Over 99% nickel and 97% cobalt were extracted via a two-stage semi-continuous extraction with a pH profile of 4.5/5.0 for E1/E2 and an O/A ratio of 2.2, resulting in less than 2.0% manganese and negligible magnesium and calcium in the loaded organic solution. More than 95% co-extracted manganese was readily scrubbed via two stages of semi-continuous scrubbing, resulting in less than 1.0 mg/L Mn left in the scrubbed organic solution. Moreover, 98.8% nickel and 99.1% cobalt could be stripped using a two-stage semi-continuous stripping with 1.5 M H2SO4. Based on the test results, a proposed process flowsheet was developed for nickel and cobalt recovery and purification.