The Applicability of Debye-Hückel Model in NaAl(OH)4-NaOH-H2O System

Focusing on the most important NaAl(OH)4-NaOH-H2O system in the industry of alumina production, the feasibility of establishing a calculation model of activity coefficients according to Debye-Hückel theory via the equilibrium solubility data of sodium aluminate solution is discussed in this paper. Firstly, the hypotheses for applying Debye-Hückel theory into NaAl(OH)4-NaOH-H2O system are involved and the values of parameters are determined. Then the applicability of Debye-Hückel model in NaAl(OH)4-NaOH-H2O system is testified. The results indicate that Debye-Hückel model is applicable to the establishment of calculation model of activity coefficients in NaAl(OH)4-NaOH-H2O system and the value of ?NaAl(OH)4 is estimated as 0.3595 nm.     

The Applicability of Debye-Hückel Model in NaAl(OH)_4-NaOH-H_2O System

1 INTRODUCTION NaAl(OH)4-NaOH-H2O system plays a paramount role in the industry of alumina production, and the calculation of its activity coefficients can not only aid to perfect the theory of alumina production, but also accelerate the research and the development of new technology for reducing the production cost and energy consumption. However, the solution in alumina industry has high concentration with extremely complex structure, and the properties of the solution are easily affe…     

Activity coefficient calculation model for NaAl（OH）4-NaOH-H2O system

Resorting to Debye-Hückel equation, the conception of the apparent dielectric constant ε' of sodium aluminate solution is introduced. By supposing that all the influences are attributed to it, ε' is successfully related to caustic ratio αK, concentration mNaoH, T and temperature T. Then an activity coefficient calculation model for NaAl (OH)4-NaOH-H2O system from 25 ℃ to 100 ℃ is established, which can be used in much wider αK and mNaoH, T ranges than those covered by the equilibrium solubility data.     

高岭石碱石灰的烧结过程

以CaO-Al2O3-SiO2-H2O和Na2O-CaO-Al2O3-SiO2-H2O体系为对象,通过热力学计算研究了高岭石(Al2O3·2SiO2·2H2O)在碱石灰烧结过程中的反应行为.结果表明:在n(CaO)/n(SiO2)为1的高岭石与氧化钙烧结过程中,形成了不能被碱液溶出的2CaO·Al2O3·SiO2和CaO·Al2O3·2SiO2.在n(CaO)/n(SiO2)为1,1.5或2的高岭石碱石灰烧结反应中,CaO·SiO2会与Na2O·Al2O3反应形成Na2O·Al2O3·2SiO2,从而导致在碱性体系中氧化铝的溶出率降低,而3CaO·2SiO2与2CaO·SiO2不与Na2O·Al2O3反应.CaF2对烧结反应有促进作用.     

硅酸钙烧成及碱液溶出性质研究

根据热力学计算 ,CaO SiO2 配料摩尔比对烧结料的组成有很大影响。实验考查了CaO SiO2 配料摩尔比为 1和 2时由CaO和SiO2 混合烧结制成CaO·SiO2 和 2CaO·SiO2 时烧结料的组成及反应率 ,并用NaOH、Na2 CO3、NaAlO2 溶液进行溶出 ,考查其反应特性