Kinetic studies for sulfur-fixing and roasting reduction of antimony sulfide for direct antimony extraction

摘要

Conventional antimony metallurgy had the problems of low-concentration SO2 pollution and high energy consumption. This work proposed a new clean metallurgy method for antimony extraction. Zinc oxide and carbon were used as sulfur-fixing and reducing agent, and metallic antimony was obtained one step while sulfur was retained as zinc sulfide, with the advantages of low temperature and no SO2 emission. The thermodynamics of the Sb2S3-ZnO-C system indicated that it is feasible to obtain antimony directly from Sb2S3. The stable zone where antimony and zinc sulfide coexisted gradually increased with increasing temperature. In addition, under 500-1000 C, the AG of the roasting reaction indicated that the increase in temperature was beneficial. The results of TG-DSC combined with XRD and SEM indicated that the reaction was composed of two stages: sulfur fixing reaction and reducing reaction. Using kinetics, the average activation energy of the two stages calculated were 233.4 kJ/mol and 288.59 kJ/mol, with lnA (A represents frequency factor) of 41.92 s(-1) and 40.7 s(-1). Their reaction models were A(2) and P-4, respectively. The kinetic equations of the two reaction stages are shown as follows (a represents the reaction fraction):