Foundamental Physical Properties Research On The Multicomponent Electrolytes Solution In The Chromate Cleaner Production Process With Sub-molten Salt Medium

Physicochemical property data are of great importance in theoretical investigation of aqueous electrolyte solution and industrial design of chemical and hydrometallurgical processes. The New Cleaner Production Technology of Chromate (NCPTC) developed by the Institute of Process Engineering, Chinese Academy of Sciences achieves the great improvement of resource conversion efficiency, enables the comprehensive utilization of the valuable components in chromite and zero emission of the chromium-containing residue, establishes an eco-chemical mode with inner recycle of the reaction media and is expected to become the updating technology for the chromate production industry of China. The needs for physicochemical property of the multicomponent electrolytes system become imperative and urgent. By selecting the most important ternary system of KOH-K2Cr04-H2O as our research target, the densities and viscosities of the said system were investigated in this thesis. The results of this work will be instructive and of great importance for both foundamental rasearch and industrial application.The following innovative achievements and progress were exhibited: (1) The density and viscosity of the ternary system (KOH-K2CrO4-H2O) over the range of experimental conditions (15≤T/℃< 60,0.5≤c (KOH)/ mol·L-1≤3 and 0≤c (K2CrO4)/mol·L-1< Saturation) were studied. It can be found that the densities decrease linearly with the increase in temperature, and increase linearly with the increase in chromate or hydroxide concentration. The nature logarithm of the mixture viscosity display satisfactorily linear dependence on chromate and hydroxide concentration, and the fitting of the curve to temperature accords with second-order polynomial equation.(2) Regression equations for viscosity and density were obtained with a least-squares method and the calculation results are consistent well with the experimental data.(3) By using the Pitzer model, the volumetric ion interaction parameters at 25℃,30℃,40℃,50℃,60℃for the binary systems (KOH-H2O and K2Cr04-H2O) were evaluated from their density data and the parameters were used to predict the densities of the ternary system (KOH-K2Cr04-H2O). The predicted density data are in good agreement with the experimental results. That provides reliable parameters and theoretical basis for the calculation of the multicomponent electrolytes solution densities.(4) A calculator tool for the density and viscosity of the ternary system (KOH-K2CrO4-H2O) over low temperature ranges was built based on the established regression equations by using Java computer language. It will be more flexible and convenient and have good application in the industrial process. This work gives a foundation for the establishment of the physicochemical property database.