Extraction of tungsten from low grade Wolframite Jig concentrate

Abstract

- Tungsten, hecause of its high strength and melting point occupies a prime position amongst the metals.With depletion of high grade ores, R & D work is being pursued world over for processing of low grade and secondary resources. Recent studies carried out at NML on extraction of tungsten from jig concentrate obtained during beneficiation of low grade ores of Degana, are discussed. By following the pressure leaching - solvent extraction route, over 95% of tungsten could be extracted from the jig concentrate containing 5% W03. Parameters such as alkali concentration, temperature, pressure during leaching have been studied and optimised. Conditions for separation of tungsten from the leach solution using organic solvent, Alamine336 modified with isodecanol in kerosene, have also been studied. The effect of pH, aqueous to organic ratio during extraction and stripping of tungsten from synthetic and actual leach solutions were studied and it has been found that the loading capacity of solvent for the above solutions in the pH range 1.7-2.8 were 102 g/l and 67 g/l W03 respectively. The lowering of the metal loading with actual leach solution is mainly due to the presence of impurities and their precipitation as tungsten-organic complex near the aqueous phase. Finally, ammonium paratungstate (APT) was made from the solution by crystallization. The purity of APT produced was 99.75% with an overall recovery of 85% tungsten.