A Study on Optimization of Processing Parameters for Synthesis of Calcium Hydroaluminosulfate Using Response Surface Methodology

The synthesis rate of calcium hydroaluminosulfate, which has an important effect on desulfurization and desilicon in alumina production, was studied in this research; Based on the analysis of the two-level multifactor test, the reaction temperature (°C), reaction time (min), Na₂SO₄ concentration in solution (g/L) and total alkali concentration (g/L). It is important to emphasize the significant factors that affect the synthesis of calcium hydroaluminosulfate have been screened out. Taking the significant factors as the study object, and by the central composite experimental design and response surface analysis to simulate the synthesis process of calcium hydroaluminosulfate, a prediction model of the synthesis rate of calcium hydroaluminosulfate has been got. The technological conditions are obtained by optimization as that: reaction temperature 75 °C, reaction time 65 min, Na₂SO₄ concentration in solution 40 g/L and total alkali concentration 45 g/L. Under this condition experiment, synthesis rate of calcium hydroaluminosulfate obtained was 69.72%, with the small difference from model prediction value 70.24%. This illustrates that the prediction model and the optimized process conditions can be used to guide the experiment and production.