Separation of Tungsten from Phosphorus-Containing Molybdate Solution Using Solvent Extraction with Primary Amine N1923

Abstract

A solvent extraction process for separation of tungsten from phosphorus-containing molybdate solution was developed using acidified primary amine N1923 as extractant. Most tungsten combines with phosphorus to form phosphorus-containing polymeric ions over a proper pH range, while the dominant form of molybdenum is still monomeric ions (MoO42−). The former can be preferentially extracted by acidified N1923. The initial pH, extractant concentration, 2-octanol concentration, and temperature were optimized. By employing an initial pH of 7.5, 15% by volume N1923, 5% by volume 2-octanol, T = 20°C, and O:A ratio of 1:1, 97.0% tungsten was extracted in a single stage, while limiting molybdenum coextraction to 12.5%. The concentration of WO3 in the raffinate was reduced to 0.28 g/L after two-stage continuous countercurrent extraction.