酸化法从盐湖老卤中提取硼酸工艺研究

On the basis of phase diagram of the system (H3BO3-MgCl2-H2O) at 0℃ and 25℃, the effect of pH, freezing temperature, and freezing time were investigated in order to recovery boron from the mother liquor brine after potassium extracting in Qaidam Basin. A series of operating conditions including acidizing, freezing and separating had been studied, and the optimum conditions were obtained with VHCl/Vbrines = 4:125, 3 h freezing time at 0℃ and 5 h in -10℃, respectively. The result showed that boron recovery rate is more than 75% in one single recycling, and the purity of boron acid reached 99% after re-crystallizing and drying of the crude boric acid.