Removal of Iron from Polluted Tungsten Powder by Acid Leaching for Recovery of Tungsten

Iron-bearing tungsten powder generated during the reduction of tungsten oxide is an important secondary material. The aim of this study is to remove iron from polluted tungsten powder by acid leaching. First, the optimal conditions for hydrochloride acid leaching were found to be a temperature of 80°C, acid concentration of 45 g/L, liquid-to-solid ratio of 9:1, and leaching time of 4 h. The highest removal rate of iron was 84.98% with a Fe content of 1076 ppm in the tungsten powder. Subsequently, the effects of different acid leaching agents and processes on the removal results were investigated. We found that a high iron removal rate of > 99% and a minimum iron content of 16–17 ppm in the purified tungsten powder were obtained in both HCl-H2O2 and H2SO4-H3PO4 solutions after two-step leaching. Moreover, this decontamination process has the same purifying effects on other impurity elements.