Separation of tungsten from molybdate using solvent extraction with primary amine N1923

Abstract

The separation of tungsten and molybdenum from solutions containing high concentrations of W(VI) and Mo(VI) using solvent extraction with a primary amine extractant N1923 was studied. W(VI) was selectively extracted over Mo(VI) by acidified N1923 at an equilibrium pH of 7.0. The extractant acidification with HNO3 performed better than with H2SO4 or HCl. The separation factor of W(VI) over Mo(VI) (βWO3/Mo) was mainly affected by the concentration of WO3. The co-extracted Mo(VI) could be scrubbed using ammonia solutions. The concentration of WO3 decreased from 43.6g·L−1 in the feed solution to 5mg·L−1 in the raffinate by a process consisting of two-step extraction and scrubbing, resulting in the decrease in WO3/Mo mass ratio from 1.7 to less than 5×10−4. This could meet the requirement on the preparation of ammonium molybdate (MSA) with MSA-0 grade of Chinese standards. A new solvent extraction process was developed to completely separate W(VI) from molybdate.