Phase Equilibrium Study of the Mixed Solvent System KCl−KBr−(CH₂OH)₂(50%)−H₂O at 298.15 K

Addressing the challenges of difficult chloride separation and bromine resource loss due to the formation of chlorobromide solid solutions during the development of high‑bromine underground brines, this study takes the K(Cl, Br) solid solution as the research object. Using the isothermal dissolution equilibrium method, the solid–liquid equilibrium data of the KCl–KBr–(CH₂OH)₂(50%)–H₂O mixed solvent system were determined at 298.15 K, and the corresponding phase diagram was plotted. Compared with other previously reported KCl–KBr–X solvent systems, the phase diagram obtained in this work shows an independent KCl single‑salt crystallization region. Based on this phase diagram, a process route was designed to separate KCl from the K(Cl, Br) solid solution, achieving efficient potassium chloride separation and enrichment of bromine resources. This study provides a new method for separating K(Cl, Br) solid solution and offers reference value for the high‑value utilization of similar brine resources.