According to the ion and molecule coexistence theory, a thermodynamic model of lead oxide activity in PbO-CaO-SiO2-FeO-Fe2O3 slag system was established at the temperature of 1273-1733 K. The activities of PbO in slag were calculated, and their equal activity curves were plotted. The influences of slag basicityQ, iron oxide rateR and temperatureT on activityNPbO and activity coefficientγPbO were also investigated. Results show that the calculated values ofγPbO are in good agreement with the reported experimental data, showing that the model can wholly embody the slag structural characteristics.NPbO departures positively from Raoult values, and increases with increasing PbO content in slag but changes little withT.γPbO increases with increasingQ, and goes through the maximum with increasingR for basic slag (Q>0.3). Results can be applied to the thermodynamic research and operational optimization of modern lead smelting technologies.%基于炉渣结构分子和离子共存理论,建立1273~1733 K下的PbO-CaO-SiO2-FeO-Fe2O3渣系氧化铅活度热力学模型,计算PbO活度并绘制等活度曲线,考察炉渣碱度Q、氧化铁比率R和温度T对活度NPbO和活度系数γPbO的影响.结果表明,活度系数γPbO的模型计算值与文献测定值吻合程度高,说明该模型能较好地反映该渣系结构本质;NPbO呈拉乌尔正偏差,且随渣中PbO含量的升高而增大,但受温度的影响不明显;γPbO 随Q的升高而增大;对于Q>0.3的碱性渣,γPbO随R的升高而出现极大值.该研究结果可用于现代炼铅工艺的热力学研究和操作优化.
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