Removal of Arsenic from Leaching Residue of Tungsten

After years of exploitation of tungsten ore in China, the average grade of tungsten ore has decreased obviously, and the contents of impurities are getting higher and higher. Arsenic is commonly present in wolframite [(Fe, Mn)WO4] resulting in As-containing leaching residue. The residue is therefore classified as hazardous waste due to its heavy metal content, especially the arsenic content up to 2 wt%. The arsenic has to be removed before the residue can be used or treated. A technique involving sodium carbonate roasting-water leaching has been developed to remove arsenic from tungsten leaching residue efficiently. The optimized parameters were determined experimentally, and the reaction mechanisms have been analyzed by FactSage 8.1. The results show that the arsenic content in the residue can be reduced below 0.1% and the tungsten in the residue is also recovered in the same time.