Selective reduction of lead sulfate containing slag using the fluidized bed reactor

Abstract Lead sulfate containing residue is a hazardous waste that should be treated cleanly and efficiently for environment protection and resource sustainability. In this work, a novel reduction-sulfurization process using a fluidized bed reactor was investigated for treating lead sulfate containing residue. The effects of temperature, hydrogen ratio, reaction time and gas flow rate on the conversion of PbSO4 and selectivity of PbS were studied. The results showed that reducing the reaction temperature and hydrogen ratio improved the PbS selectivity, while increasing the reaction time and gas flow rate had no significant effect. In the optimal process conditions, i.e., the reaction temperature 650 °C, hydrogen ratio 20%, reaction time 5 min, and gas flow rate 550 mL min−1, the conversion and sulfurization ratios of PbSO4 were 96.2% and 84.8%, which were 2.0% and 40.1% higher than those obtained in a fixed bed reactor, suggesting that enhanced mass transfer in the fluidized bed reactor benefited the phase transformation of PbSO4 to PbS. This work offers a highly potential approach for processing lead sulfate containing wastes in a clean and economical manner.