Thermodynamic and Experimental Analyses of the Carbothermic Reduction of Tungsten Slag

Abstract

Tungsten slag contains valuable elements, such as Bi, W, Fe, Nb, and Mn, and harmful elements, such as Pb. Here, the carbothermic reduction of tungsten slag was analyzed thermodynamically using FactSage thermochemical software and verified experimentally. CaO, SiO2, and Al2O3 could not react with C and were the major constituents of the slag. WO3, Fe2O3, Nb2O5, and MnO2 were reduced and collected in the alloy, and Bi2O3 and PbO were reduced and formed Bi and Pb, respectively, which volatilized and collected in the fumes. Increased temperature and decreased reductant addition contributed to an increase in the recovery of Nb, while the recovery of W was less affected. At reduction conditions of 14–16% reductant addition and 1500–1600°C, the recovery percentage of W, Fe, and Nb were over 90%, the recovery percentage of Mn was over 50%, and Bi and Pb were collected in the fumes.