Separation of chlorine–bromine-based solid solution in bittern tail solution by phase equilibrium

Solid solution hinders the extraction of bromine resources from bittern. To separate chlorine–bromine-based solid solution in bittern tail solution, the solubilities of the quaternary system KCl–KBr–NaCl–NaBr–H₂O and its ternary subsystem NaBr–KBr–H₂O at 333.15 K were determined by the isothermal dissolution method, and the corresponding phase diagrams were conducted. An improved model was employed to predict the solubilities of the quaternary system KCl–KBr–NaCl–NaBr–H₂O at 333.15 K. The calculated results coincide with the experimental values, implying that the prediction method is feasible. A closed loop crystallization process for the separation of chlorine–bromine-based solid solution in bittern tail solution was proposed and NaBr was obtained with a purity of 98.23%.