PERSPECTIVE SULFUR-CONTAINING ORGANOPHOSPHORUS EXTRACTANTS OF HEAVY METALS

The possibility and prospects of using tertiary phosphine sulfides synthesized on the basis of on affordable and secondary raw materials as effective extractants of heavy metals have been investigated

High Purity Nickel Recovery from an Industrial Sidestream Using Concentration and Liquid–Liquid Extraction Techniques

This article outlines an alternative flowsheet for the purification of a multi-metal industrial sidestream (16.3 g/l Ni, 0.7 g/l Co, 0.6 g/l Ca and 1.6 g/l Mg) to allow high-purity nickel recovery. The methodology comprises an initial evaporation step to achieve Ca removal followed by impurity (Ca, Mg) and valuable (Co, Ni) element separation via two-step solvent extraction with organophosphorus extractants. Results indicate that > 80% of Ca is selectively removed as CaSO4·2H2O by evaporation with a concentration degree > 6. In the following treatment, ~ 90% of residual Ca (0.6 g/l) can be selectively extracted with Na-D2EHPA. The subsequent solvent extraction step with Na-Cyanex 272 separates Co (> 99%) and Mg (> 95%). The resultant nickel sulfate solution (61.7 g/l Ni, 0.3 g/l Mg and Co 0.007 g/l) of > 99.5% purity can be directly integrated into state-of-the-art nickel recovery processes.