The Optimization And Complementarity Of Thermodynamic Database For Alumina Production

During the use of Thermodynamic Database for Alumina Production 1.0 version, many problems were found in spite of its good performance. In this paper the software optimization and edition upgrade were carried out to solve those problems. And the new estimation model for activity coefficients inNaAl(OH)4-NaOH-H2O system was established, which was used in the database software to deal with the relevant thermodynamic calculations immediately.The new version software was developed mainly using the popular computer technologies nowadays such as Windows 2000, Access 2000, and DAO database link technology. According to the demand of the software exploration, all old codes, which involve user interface program, database join program, equilibrium reaction program and calculation program, were completely amended to optimize the whole database capability and the frame was also changed. Main disadvantage of the database 1.0 version were overcomed during the further exploration.Focusing on the NaAl(OH)4-NaOH-H2O system which plays a paramount role in the industry of alumina production, a complete method to establish the estimation model for activity coefficients in NaAl(OH)4-NaOH-H2O system by regressing the solubility data of gibbsite in NaOH solution based on the Debye-Huckel theory was provided in this paper. It includes: 1) bringing forward the hypothesis for applying the Debye-Huckel theory into the NaAl(OH)4-NaOH-H2O system and giving the values of parameters; 2) Discussing the applicability of the Debye-Huckel theory in the NaAl(OH)4-NaOH-H2O system; 3) Obtaining the ultimate estimation model for activtity coefficients in NaAl(OH)4-NaOH-H2O system. Accordingly, the estimation model over the range of temperatures from 40 to 100 wasachieved successfully in this study by solving the range limits of the values of aK and mNaOHT calculated from solubility data, introducing the conception of 'the apparent dielectric constant of H2O in sodium aluminate solution', and giving the calculation method for the dielectric constant. The model was applied in database subsequently.The facility, veracity, applicability and security of the database software were greatly developed basing on the compute technology and chemistry theory. The new version of the software possesses the satisfying lifecycle and applicable future.