CaO-MgO-FeO-Al_2O_3-SiO_2-P_2O_5渣系与碳饱和铁液间硫分配比的热力学模型

在富氧顶吹熔融还原冶炼高磷铁矿的工艺研究中,以共存理论为基础,结合全选主元松弛迭代法,利用VB 6.0计算了CaO-MgO-FeO-Al2O3-SiO2-P2O5渣系中结构单元或离子对的质量作用浓度,并建立了该渣系与碳饱和铁液间硫分配比的热力学模型,由该模型计算的硫分配比与工艺中实测的硫分配比吻合程度较好,说明利用共存理论所建立的脱硫模型能适用在熔融还原高效脱磷熔渣。     

CaO-SiO2-MgO-Al2O3渣系渣铁间硫分配比热力学模型

 为了探明高炉渣系组成对高炉渣脱硫能力的影响,根据分子-离子共存理论,建立了CaO-SiO₂-MgO-Al₂O₃高炉渣系与铁液间硫分配比的热力学模型,利用试验测定值对其进行验证与修正,探究碱度R、w((MgO))/w((Al₂O₃))和w((Al₂O₃))对炉渣脱硫能力的影响。研究结果表明,修正后的CaO-SiO₂-MgO-Al₂O₃高炉渣系硫分配比(L_S)热力学模型能较好地预测熔渣的脱硫能力,修正后的相对误差为8%,较修正前的相对误差降低了11%;当w((MgO))/w((Al₂O₃))=0.25~0.45,w((Al₂O₃))=15%时,随着碱度R的增加,炉渣的脱硫能力(L_S)增大;当w((Al₂O₃))=15%,R=1.15~1.25时,随着w((MgO))/w((Al₂O₃))的增加,炉渣的脱硫能力(L_S)增大;当w((MgO))/w((Al₂O₃))=0.25~0.45,R=1.20时,随着w((Al₂O₃))的增加,炉渣的脱硫能力(L_S)减小,故高Al₂O₃条件下应适当增加炉渣中的w((MgO))/w((Al₂O₃))。     

A thermodynamic model for calculation of sulfur distribution ratio between CaO- SiO2- Al2O3- Na2O- TiO2- (MgO) slags and carbon saturated hot metal

The ion and molecule coexistence theory (IMCT) indicates that the mass action concentrations of structural units or ion couples in slags can represent the chemical reaction ability as the traditional slags activity.By establishing the mass action concentrations equations of structural units or ion couples in the CaO- SiO2- Al2O3- Na2O- TiO2- (MgO) slags, the mass action concentrations were solved by Matlab, so as to build a thermodynamic model for calculating the sulfur distribution ratio between slags and carbon saturated hot metal under 1450??.The calculated sulfur distribution ratio of model agrees well with the experimental sulfur distribution ratio, which can help to predict the sulfur distribution ratio between slags and carbon saturated hot metal.The thermodynamic model can quantitatively determine the respective sulfur distribution ratio of CaO, Na2O and total sulfur distribution ratio in slags.Through the calculated results, the influencing factors on total sulfur distribution ratio were analyzed. In addition, the model can quantitatively calculate the contribution of CaO and Na2O on total sulfur distribution ratio, and qualitatively describe their trend affected by other factors.     

A Thermodynamic Model for Representation Reaction Abilities of Structural Units in Full Composition Range of Fe–Si Binary Melts Based on the Atom–Molecule Coexistence Theory

A thermodynamic model for calculating the mass action concentrations of structural units in Fe–Si binary melts based on the atom–molecule coexistence theory, i.e., the AMCT–N_i model, has been developed and verified through comparing with the reported activities of both Si and Fe in the full composition range of Fe–Si binary melts at temperatures of 1693, 1773, 1873, and 1973 K from the literature. The calculated mass action concentration N_Si of free Si or N_Fe of free Fe in the full composition range of Fe–Si binary melts has a good 1:1 corresponding relationship with the reported activity a_R,Si of Si or a_R,Fe of Fe relative to pure liquid Si(l) or Fe(l) as standard state. The calculated mass action concentration N_Si of free Si has a good corresponding relationship with the calculated activity a_%,Si of Si referred to 1 mass% of Si as standard state as well as the calculated activity a_H,Si of Si relative to the hypothetical pure liquid Si(l) as standard state. The calculated activity a_%,Si or a_H,Si of Si is much greater than the calculated mass action concentration N_Si of free Si in Fe–Si binary melts. The reaction abilities of both Si and Fe show a competitive or coupling relationship in Fe–Si binary melts at the above‐mentioned four temperatures. The calculated mass action concentrations N_i of six structural units as Fe, Si, Fe₂Si, Fe₅Si₃, FeSi, and FeSi₂ cannot show the linear relationship with the calculated equilibrium mole numbers n_i in 100‐g Fe–Si binary melts simultaneously. A spindle‐type relationship between the calculated mass action concentration N_i and the calculated equilibrium mole number n_i of FeSi and FeSi₂ in Fe–Si binary melts has been found.