The separation and recovery of copper（Ⅱ）, nickel（Ⅱ）, cobalt（Ⅱ）, zinc（Ⅱ）,and cadmium（Ⅱ） in a sulfate-based solution using a mixture of Versatic 10 acid and Mextral 984H

We studied the separation and recovery of copper（Ⅱ）, nickel（Ⅱ）, cobalt（Ⅱ）, zinc（Ⅱ）, and cadmium（Ⅱ） frommagnesium and calcium, using synergistic solvent extraction （SSX） in a typical hydrometaUurgical waste solu-tion. A mixture of Versatic 10 acid and Mextra1984H, diluted with Mextral DT100, was used to obtain fundamen-tal data on pH and distribution isotherms, as well as the kinetics of extraction and stripping. We also investigatedthe main effects and interactions of common solvent extraction factors： the extraction pH at equilibrium, thetemperature, and the extractant concentration. The synergistic effect for extracting metals was confirmed. Theresults showed that the addition of Mextral 984H enhanced the separation factors of copper, nickel, cobalt,zinc, and cadmium over magnesium and calcium. Compared with Versatic 10 acid alone, for a mixture of0.5 mol.L^-1 Versatic 10 acid/0.5 mol.L^-1 Mextra1984H, pHso values of copper, nickel, cobalt, zinc, and cadmi-um were found to be 〉2.0, 3.30, 2.85, 0.95, and 1.32 pH units, respectively. The ApHsocZn-Mg/and ApHsoczn ca9values were 3.27 and 2.25, respectively, indicating easy separation and recovery of copper, nickel, zinc, cobalt,and cadmium. The extraction and stripping of copper, cobalt, zinc, and cadmium were fast, with 90% of themetal transferred in 2 min. We next studied whether the metals could be stripped from the extracted liquid se-lectively in sequence, by using sulfuric acid at different concentrations. The influence of the molecular structureof the oxime and carboxylic acid components upon the synergistic effects was identified by numerical analysis.Excellent separation of copper, nickel, cobalt, and zinc over magnesium and calcium was achieved with thissynergistic solvent extraction system.