Recovery of nickel and cobalt from laterite leach solutions using direct solvent extraction: Part 1 — selection of a synergistic SX system

摘要

The separation of nickel and cobalt from impurities such as manganese, magnesium and calcium usingsolvent extraction with Versatic 10 was largely improved, by the addition of a synergistic reagent LIX63 (ana-hydroxyoxime) or 4PC (a pyridine carboxylate ester). With the organic systems containing Versatic 10alone, the separation factors of nickel and cobalt over manganese were 6 and 15 respectively. When 4PC wasadded to the system, these increased to 147 and 1870 respectively, and with LIX63, they were even higher at534 and 7720 respectively. This indicates that the synergistic solvent extraction (SSX) system with Versatic10 and LIX63 performed very well and better than that with Versatic 10 and 4PC.The SSX system consisting of 0.5 M Versatic 10, 0.45 M LIX63 and 1.0 M TBP in Shelisol D70 performed thebest among the systems tested containing LIX63. After a single contact, the extraction of Ni and Co was 99.6%and 96.9%, respectively. Only 6 mg/L Mn, 8 mg/L Mg and 1 mg/L Ca were found in the loaded organicsolution. The manganese scrub efficiency was 97.7% at pH 5.3, resulting in a scrubbed organic solutioncontaining only 0.8 mg/L Mn. Over 99% nickel, cobalt and manganese were stripped at pH 2.0, indicating easystripping of these metals.The SSX system consisting of 0.5 M Versatic 10 and 1.0 M 4PC in Shellsol D70 performed the best among thesystems tested containing 4PC. After a single contact, the extraction of Ni and Co was 99.4% and 89.4%,respectively. Some 200 mg/L Mn, 10 mg/L Mg and 48 mg/L Ca were found in the loaded organic solution. Themanganese could not be scrubbed at the tested pH range of 5.4-6.0. Very fast Ni and fast Co stripping kineticswere observed, however, the Mn stripping kinetics were very slow. After 2 min of stripping, only 1.22% Mnwas stripped.It is concluded that the SSX system containing 05 M Versatic 10, 0.45 M LIX63 and 1.0 M TBP performedmuch better than the SSX system containing 05 M Versatic 10 and 1.0 M 4PC in terms of both manganeseand calcium behaviour in extraction, scrubbing and stripping.