Selective Recovery of Iron by Solvent Extraction from Ni-Laterite Leach Solutions, as Precursor for the Synthesis of High Added-Value Nanomaterials

Abstract

Iron is the major impurity in the pregnant leaching solutions (PLS) derived from heap and atmospheric acid leaching of low-grade laterite ores. The PLS can be considered as a secondary resource for the synthesis of high added-value iron nanomaterials, provided that the iron is selectively separated from the polymetallic PLS solution. In this study, the feasibility of selective iron separation was investigated by applying a solvent extraction technique based on the use of Di-2-ethylhexyl phosphoric acid (D2EHPA) and Tri-butyl phosphate (TBP) extractants. The effect of several parameters such as initial pH and PLS composition was studied to identify the conditions allowing the maximum possible separation of iron with the minimum co-extraction of other valuable metals. It was found that the best separation of Fe could be obtained when the initial pH of the aqueous phase was regulated close to 1.4. The recovery of iron from the loaded organic phase was studied using sulfuric acid as stripping reagent and elemental iron as solid reducing agent. It was found that 90% of Fe(III) could be stripped out by applying the metallic iron (galvanic) stripping.