PbSO4 Reduction Mechanism and Gas Composition at 600–1000°C

A promising lead-containing waste recycling method, with sulfur conservation and reductive sulfur-fixing co-smelting process (RSFCS), is proposed. This work investigated the PbSO4 reduction equilibrium composition, phase conversions, microscopic transformation mechanisms during RSFCS at different temperatures, times, CO-CO2 mixtures using thermodynamic modeling, thermogravimetric analysis, x-ray diffraction, SEM-EDS analysis techniques. At same time, gaseous products were collected analyzed. The results showed that three paths existed: (1) $$ \to ^{{ {\text{CO/CO}}_{{2}} }} PbO·PbSO4+SO2 $$\to }}$$ 2PbO·PbSO4+SO2 4PbO·PbSO4+SO2 PbO+SO2 Pb; (2) PbS; (3) → PbO·PbSO4+SO3 2PbO·PbSO4+SO3 4PbO·PbSO4+SO3 PbO+SO3. Reduction temperature CO concentration determined as major factors in reduction. In a relatively weak atmosphere low temperature, xPbO·PbSO4 (x = 1, 2, 4), PbO, Pb, SO2 products. When increased, was selectively reduced to PbS, fixed instead of emitting SO2/SO3.