Extraction and separation of nickel and cobalt with hydroxamic acids LIX®1104, LIX®1104SM and the mixture of LIX®1104 and Versatic 10

Solvent extraction and separation of Ni and Co in a typical synthetic laterite leach solutions with LIX®1104 (unmodified), LIX®1104SM (modified), and the mixed LIX®1104/Versatic 10 were comparatively investigated to obtain fundamental data on pH and distribution isotherms, extraction and stripping kinetics, phase separation properties, and to identify any synergistic and antagonistic effect for potential applications.The results show that LIX®1104 was highly selective for Zn, Co and Ni over Mn, Mg and Ca, with their pH50 differences over manganese being 2.2, 1.9 and 1.8 pH units, respectively. In comparison, the pH isotherms of Zn, Ni, Co and Mn with LIX®1104SM were shifted to a higher pH range, but the pH50 differences all exceeded 2 pH units, suggesting ready separations of these valuable metals from Mn, Mg and Ca. For the synthetic laterite leach solution with 3.0 g/L Ni and 0.19 g/L Co, at an A/O ratio of 0.8 and pH 6.5, two theoretical stages could achieve a few mg/L Ni and Co in the raffinate. The extraction kinetics of Ni, Co, Cu and Zn with LIX®1104SM was fast. Except for copper and iron, other metals extracted can be stripped with 35 g/L H2SO4 at 23 °C. The copper and iron can then be stripped at higher temperature with a stronger acidic solution. The rate of phase disengagement with LIX®1104 and LIX®1104SM was comparable to commercial reagents such as D2EHPA and Versatic 10. The mixed LIX®1104 and Versatic 10 system did not offer an additional advantage in terms of selectivity and extraction efficiency.

► LIX®1104 is highly selective for Zn, Co and Ni over Mn, Mg and Ca.
► With LIX®1104, the ΔpH50 of Zn, Co and Ni over Mn are in 1.8–2.2 pH unites.
► With LIX®1104SM the ΔpH50 of Zn, Co and Ni over Mn are all exceeded 2 pH units,
► The extraction and stripping kinetics of metals with LIX®1104SM was fast.
► The phase disengagement with the two reagents was similar to commercial reagents.