We studied the separation and recovery of copper(Ⅱ)

nickel(Ⅱ)

cobalt(Ⅱ)

zinc(Ⅱ)

and cadmium(Ⅱ) from magnesium and calcium

using synergistic solvent extraction (SSX) in a typical hydrometallurgical waste solution. A mixture of Versatic 10 acid and Mextral 984H

diluted with Mextral DT100

was used to obtain fundamental data on pH and distribution isotherms

as well as the kinetics of extraction and stripping. We also investigated the main effects and interactions of common solvent extraction factors:the extraction pH at equilibrium

the temperature

and the extractant concentration. The synergistic effect for extracting metals was confirmed. The results 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 of 0.5 mol·L

-1

Versatic 10 acid/0.5 mol·L

-1

Mextral 984H

ΔpH

50

values of copper

nickel

cobalt

zinc

and cadmium were found to be 2.0

3.30

2.85

0.95

and 1.32 pH units

respectively. The ΔpH

50(Zn-Mg)

and ΔpH

50(Zn-Ca)

values 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 the metal transferred in 2 min. We next studied whether the metals could be stripped from the extracted liquid selectively in sequence

by using sulfuric acid at different concentrations. The influence of the molecular structure of 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 this synergistic solvent extraction system.