Abstract:The present technology of extracting tungsten from alkaline solution using quaternary ammonium salt as extractant has problem of disequilibrium of alkali and water because the sodium hydroxide is consumed and regenerated liquid is produced in the regeneration procedure. Aiming at this problem, the direct extraction of tungsten from simulated autoclave-soda leaching liquor was researched in order to shorten the flowsheet and cancel the regeneration process by using mixed quaternary ammonium salt of bicarbonate and carbonate as extractant. The effect of various factors, such as temperature, phase ratio, contact time and Na₂CO₃ concentration in leaching solution on the extraction of tungsten and the behaviors of impurities in the extraction were investigated. The saturated loading capacity (for WO₃) of organic was measured and the extraction isotherm was plotted. On this basis, the simulated counter current extraction was carried out. The results show that the mixed quaternary ammonium salt of bicarbonate and carbonate can selectively extract tungsten effectively from the autoclave-soda leaching liquor of tungsten ore. The regeneration procedure can be cancelled in the new process although both the extraction rate of WO₃ and removing rates of P and As are a little lower than those in the process using quaternary ammonium salt of carbonate as extractant. For that, the balance of soda and water in the whole extraction process is realized. The extraction rate of WO₃ is 95.64% and the removing rates of P and As are higher than 90% in the 9-stage simulated countercurrent extraction.

Key words: quaternary ammonium; tungsten; solvent extraction