China Nonferrous Metallurgy

To analyze the root cause of the great difference between the synthetic slag (slag prepared by chemical reagent) and premelted slag (molten slag in enterprise smelting) for physicochemical properties of PbO-Fe_xO-CaO-SiO₂-ZnO, the loss law of slag volatile for premelted slag and synthetic slag with the same composition with the 61.3% PbO are determined by FactSage and thermogravimetry, further, the volatile mechanism of lead slag is analyzed through combinate XRD and SEM-EDS analyze the final slag. The results shown that the volatilization of synthetic slag is more severe than that of premelted slag, synthetic lead slag had volatilized 12.7% before melting, and the main phase is Spinel of high melting point after volatilizing. But leads in premelted slag exists in the silicate is limited by the three-dimensional diffusion of silicate, which lead to a small amount of volatilization reaching the melting temperature. The mechanism function of weight loss process at high temperature of premelted slag and synthetic slag respectively are controlled by three-dimensional diffusion spherical symmetry Jander equation and Z-L-T equation, and the average apparent activation energies are 478.6kJ·mol^-1 and 352.9kJ·mol^-1.