Abstract
The recovery process of the caustic soda solution is important in the aluminum manufacture in order to build up the industrial process for refining alumina and finishing aluminum products. Methanol is found to be the most effective anti-solvent in the caustic soda solution for reducing the gibbsite solubility because methanol has low vaporization heat, and can be efficiently separated from the caustic soda solution. This process is powerful for the recovery process of a concentrated caustic soda solution up to 500 g/L NaOH which leads to the significant increase in the dissolution rate of alumina and/or aluminum at the atmospheric pressure. Adaptive methods for recovering the caustic soda solution with different concentrations were proposed according to the characteristics of gibbsite solubility. Synergy of these advantages of the present recovery method will contribute to the improvement of cost performance, and the suppression of total environmental impact.
