(1. 北京科技大学 冶金与生态工程学院, 北京 100083；
2. 中国科学院 过程工程研究所 多相复杂系统国家重点实验室，北京 100190)
摘 要: 基于封闭平衡体系Gibbs自由能最小原理对精炼Si液中杂质Ca的炉渣−金属体系建立热力学模型，由该热力学模型得到Si液中Ca的摩尔分数xCa与CaO-SiO2二元渣系CaO的摩尔分数xCaO的关系和文献报道的实验结果吻合良好，即0.3＜xCaO＜0.4较有利于Si液脱Ca。热力学模型计算结果表明：Si液中Si和Ca的活度分别与SiO2和CaO质量作用浓度的比值符合炉渣−金属组元活度之间的关系式，且计算结果比文献报道的数据精度更高。因此，基于炉渣离子−分子共存理论的质量作用浓度可与经典的炉渣活度一样表征CaO-SiO2二元渣系组元的反应能力。由建立的热力学模型计算结果确定的反应[Ca]+0.5(SiO2)=(CaO)+0.5[Si]的标准摩尔反应Gibbs自由能变化表达式为 
=−89 532.7−21.8T (J/mol)。
关键字: CaO-SiO2渣系；Si-Ca熔体；最小自由能原理；热力学模型；离子−分子共存理论；Si液精炼；活度
（1. School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing,
Beijing 100083, China;
2. State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering,
Chinese Academy of Sciences, Beijing 100190, China）
Abstract:A thermodynamic model was developed for a close system of CaO-SiO2 binary slags equilibrated with Si-Ca binary metal system based on the minimized Gibbs free energy principle of a close system, in which the reaction ability of components in slags was presented by the mass action concentration according to the ion and molecule coexistence theory. The calculated relationship between mole fraction of Ca, xCa, in silicon melt and mole fraction of CaO, xCaO, in CaO-SiO2 slags is in good agreement with the reported results, i.e., the optimal composition range for xCaO is 0.3＜xCaO＜ 0.4. The calculated relationship between the ratio of Si activity in melt to mass action concentration of SiO2 in slags and the ratio of Ca activity in melt to mass action concentration of CaO in slags follows the intrinsic relation, while the calculated results has higher accuracy than that from the reported results based on experiments. Therefore, the mass action concentrations of components in CaO-SiO2 slags can be successfully used to present reaction ability like component activity in slags. The determined standard molar Gibbs free energy change for reaction [Ca]+0.5(SiO2)= (CaO)+0.5[Si] from the developed thermodynamic model is =−89 532.7−21.8T (J/mol) with reliable feasibility.
Key words: CaO-SiO2 binary slags; Si-Ca metal system; minimized free energy principle; thermodynamic model; ion- molecule coexistence theory; silicon refining; activity
