Nickel extraction from sulfate media with Cyanex 301 in the presence of electron donor additives

Abstract

Data is presented on the nickel(II) extraction from sulfate solutions with bis(2,4,4-trimethylpentyl)dithiophosphinic acid (HR) (Cyanex 301) diluted with nonane in the presence of electron donor additives (L). Well-known extractants and modifiers, widely used in industry, trioctyl amine (TOA), trialkyl amine (TAA), trioctyl phosphine oxide (TOPO), trialkyl phosphine oxide (TAPO), tributyl phosphate (TBP), and n-octanol, were used as additives. The interaction between nickel-loaded extracts in nonane (NiR 2) and various electron donor additives was studied using an electronic spectroscopy method. It is shown that n-octanol and TBP do not interact with NiR 2 in the organic phase, as a result of no change in the square planar configuration of the initial nickel complex, while TOPO, TOA, and TAA form mixed complexes with nickel dithiophosphinate. For the NiR 2 and organic amine mixtures, the composition of the ternary complex having an octahedral configuration was found to be [NiR 2•2TOA] or [NiR 2•2TAA]. The introduction of additives into the organic phase results in a decrease in nickel extraction. The degree of extraction decreases in the series TAA > TOPO, TAPO >> TBP >> n-octanol. A decrease in the extractant activity resulting from the interaction between HR and L is the determinant factor during nickel extraction with bis(2,4,4-trimethylpentyl)dithiophosphinic acid in the presence of additives despite the formation of mixed nickel complexes in the HR and TOPO (TAPO) and TAA (TOA) mixtures in the organic phase. The most effective system, based on a mixture of Cyanex 301 and TAA, was proposed for nickel extraction from sulfate media, including leach liquors of oxidized nickel ores.