熔池熔炼中金属硫酸盐分解过程的热力学研究

摘要

The decomposition pressures of five metal sulfates (FeSO4, In2(SO4)3, Fe2(SO4)3, ZnSO4, PbSO4) in smelting slag were calculated with the standard equilibrium constants of related chemical reactions and the sulfate decomposition temperatures were obtained by the pressures. The metal sulfates decomposition was investigated through thermogravimetric (TG) and differential scanning calorimetry (DSC), and the TG-DSC analysis confirmed the results of thermodynamic calculation. The results show that the ability of metal sulfate decomposition can be ordered as follows (from easy to difficult): FeSO4, In2(SO4)3, Fe2(SO4)3, ZnSO4, PbSO4. The phase transition and decomposition temperatures from thermodynamic calculation are consistent with TG­DSC results. The calculated temperatures are lower than those from TG­DSC, and the difference is from 7.5 to 283.1 K. The sulfates in zinc leaching residue and iron sinking slag will decompose more thoroughly when the furnace temperature is above 1316.1 K.%利用化学反应的标准平衡常数求得冶炼废渣熔池熔炼过程中5种金属硫酸盐(FeSO4, In2(SO4)3, Fe2(SO4)3, ZnSO4, PbSO4)的分解压，确定硫酸盐在高温下发生分解反应的温度；采用热重(TG)及差示扫描量热(DSC)分析各金属硫酸盐的分解过程，验证热力学计算结果。结果表明，5种硫酸盐发生分解反应由易到难的顺序为 FeSO4、In2(SO4)3、Fe2(SO4)3、ZnSO4、PbSO4；热力学计算得到的相变温度、分解温度与DSC曲线吸热峰位置、TG曲线质量损失阶段相吻合，且理论计算温度比TG-DSC测定温度低7.5~283.1 K；熔炼炉温度达到1316.1 K以上可使浸锌渣、沉铁渣中的硫酸盐分解脱硫较彻底。