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.
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The authors express their sincere thanks to the Natural Science Foundation of China (NSFC, No. 51334008) and Postdoctoral Science Foundation of Central South University, China for financial support.
C.K. Gupta, Extractive Metallurgy of Molybdenum (Florida: CRC Press, 1992), pp. 143–146.Google Scholar