Efficient extraction of tungsten from scheelite with phosphate and fluoride.

Considering the problems of high temperature and large reagent consumption in the current alkali decomposition processes, phosphate and fluoride were adopted to extract tungsten from scheelite. The results indicated that tungsten could be efficiently extracted with a decomposition rate of > 98.0% under moderate decomposition conditions, forming fluorapatite in the decomposition residue. The decomposition yield is influenced by the calcium fluoride dosage, decomposition temperature, liquid-to-solid ratio, and holding time. Furthermore, the decomposition reaction followed the surface chemical reaction controlling step. Additionally, the phosphorus concentration in the decomposition solution was lower than 0.2 g/L. This work may provide an alternative for the efficient tungsten extraction from scheelite, especially fluorite bearing scheelite under relatively low reagent costs and temperature. [ABSTRACT FROM AUTHOR]