Removal of Fe(III) from Ni-Co-Fe chloride solutions using solvent extraction with TBP

The extraction of Fe(III), Ni(II) and Co(II) from a Ni(II)-Co(II) solution containing Fe(III) was analyzed in a chloride medium using a mixed extractant consisting of 50% ( v /v) tributyl phosphate (TBP), 20% (v/v) 2-octanol and 30% (v/v) kerosene. The extraction of 0.5 mol/L Fe(III) in 4 mol/L hydrochloric acid reached 97%, and the consumption of chloride ions was investigated. Nickel(II) ions were not detectably extracted by TBP, with an inclusion of <1.1%. Compared with Fe(III), TBP extracted only a small amount of Co(II). The iron complexes formed by TBP and 2-octanol were [H 2 FeCl 4 · 2TBP] and [H 2 FeCl 4 · 5(2-octanol)], and the possible compositions of Co-containing extracts were [H 2 CoCl 4 · 2TBP] and [H 2 CoCl 4 ] · n[2-octanol]. An industrial process consisting of two-step extraction was designed to achieve the separation of Co(II) and Fe(III), resulting in a decrease in the Fe/Co mass ratio from 0.46 to <3.5 × 10 −4 in the raffinate.