Abstract:For the recovery of sodium sulfate from high-salt wastewater, the method of evaporation crystallization is often used in industry, but there are some problems such as unclear crystallization behavior, low purity and difficult to control operating conditions. The hydrosaline solution containing sodium sulfate produced by a smelter was used as raw material, aiming at the recovery of sodium sulfate, the phase equilibria data of Na2SO4-NaCl-H2O system were systematically measured. Then on the basis of considering the dissociation reaction, ENRTL equation was used to regression the solubility data of the system, and new interaction parameters between ions were obtained to establish the phase equilibrium diagram of the system. Finally, the operation line of sodium sulfate step crystallization was drawn, and the experiment of sodium sulfate crystal recovery was carried out, and the purity of sodium sulfate crystal is 98.6%.