(1. 北京科技大學 冶金與生態(tài)工程學院, 北京 100083；
2. 中國科學院 過程工程研究所 多相復雜系統(tǒng)國家重點實驗室，北京 100190)
摘 要: 基于封閉平衡體系Gibbs自由能最小原理對精煉Si液中雜質(zhì)Ca的爐渣−金屬體系建立熱力學模型，由該熱力學模型得到Si液中Ca的摩爾分數(shù)xCa與CaO-SiO2二元渣系CaO的摩爾分數(shù)xCaO的關(guān)系和文獻報道的實驗結(jié)果吻合良好，即0.3＜xCaO＜0.4較有利于Si液脫Ca。熱力學模型計算結(jié)果表明：Si液中Si和Ca的活度分別與SiO2和CaO質(zhì)量作用濃度的比值符合爐渣−金屬組元活度之間的關(guān)系式，且計算結(jié)果比文獻報道的數(shù)據(jù)精度更高。因此，基于爐渣離子−分子共存理論的質(zhì)量作用濃度可與經(jīng)典的爐渣活度一樣表征CaO-SiO2二元渣系組元的反應能力。由建立的熱力學模型計算結(jié)果確定的反應[Ca]+0.5(SiO2)=(CaO)+0.5[Si]的標準摩爾反應Gibbs自由能變化表達式為 
=−89 532.7−21.8T (J/mol)。
關(guān)鍵字: CaO-SiO2渣系；Si-Ca熔體；最小自由能原理；熱力學模型；離子−分子共存理論；Si液精煉；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
