三水铝石在氢氧化钠溶液中的平衡溶解度热力学模型(英文)

针对拜耳法生产氧化铝过程中最为重要的NaAl(OH)4-NaOH-H2O体系,构建三水铝石溶解于氢氧化钠溶液的反应平衡常数的理论模型,并得出电解质NaAl(OH)4新的Pitzer模型参数和NaOH-NaAl(OH)4-H2O体系的热力学混合参数(温度范围298.15～373.15K)。将所得模型和参数对NaAl(OH)4-NaOH-H2O体系进行适用性分析。结果表明:将该理论模型用来计算三水铝石溶解反应的平衡常数是适用且准确的;电解质NaAl(OH)4的Pitzer模型参数β(0)(NaAl(OH)4)、β(1)(NaAl(OH)4)和CΦ(NaAl(OH)4),Al(OH)4-与OH-的二离子相互作用参数θ(OH-Al(OH)4-),以及Al(OH)4-与OH-和Na+的三离子相互作用参数ψ(Na+OH-Al(OH)4-)均与温度相关;当温度在298.15～373.15K时,预测三水铝石溶解于氢氧化钠溶液的平衡溶解度是可行的。

Thermodynamic model for equilibrium solubility of gibbsite in concentrated NaOH solutions

The thermodynamic properties of the most important NaOH-NaAl(OH)4-H2O system in Bayer process for alumina production were investigated.A theoretical model for calculating the equilibrium constant of gibbsite dissolved in sodium hydroxide solution was proposed.New Pitzer model parameters and mixing parameters for the system NaOH-NaAl(OH)4-H2O were yielded and tested in the temperature range of 298.15-373.15 K.The results show that the proposed model for calculating the equilibrium constant of gibbsite dissolution is applicable and accurate.The obtained Pitzer model parameters of β(0)(NaAl(OH)4),β(1)(NaAl(OH)4),CΦ(NaAl(OH)4) for NaAl(OH)4,the binary mixing parameter of θ(OH-Al(OH)4-) for Al(OH)4-with OH-,and the ternary mixing parameter of ψ(Na+OH-Al(OH)4-) for Al(OH)4-with OH-and Na+ are temperature-dependent.The prediction of the equilibrium solubility of gibbsite dissolved in sodium hydroxide solution was feasible in the temperature range of 298.15-373.15 K.