Impure ions removal from multicomponent leach solution of nickel sulfide concentrates by solvent extraction in impinging stream rotating packed bed

In order to separate zinc, manganese and copper from a mixed chloride solution containing nickel and cobalt, solvent extraction with Di-2-ethylhexylphosphoric acid (D2EHPA) was investigated using an Impinging Stream–Rotating Packed Bed (IS–RPB) contactor in laboratory scale. The effects of operating parameters, such as equilibrium pH, ratio of aqueous to organic flow rates, rotation speed and concentration of D2EHPA amongst other variables were examined. A McCabe–Thiele diagram of the extraction stage predicted that at a flow rate ratio of 1:1, equilibrium pH of 3.5, D2EHPA concentration of 20% (v/v) and rotation speed of 900 rpm, 99.9% of zinc, manganese and copper would be removed within three stages. With regards to the scrubbing results, the co-extracted nickel and cobalt were scrubbed efficiently from the loaded organic solution using 0.8 M HCl, The loaded-organic phase can be reused for extraction process after stripping with 3 M HCl. IS–RPB extraction system have much higher mass transfer rates compared to conventional extractors such as mixer-settler and centrifugal extractor, etc. Finally, each of impure ions in raffinate was below 5 mg/L, completely meeting the requirements of subsequent process of nickel and cobalt separation.