Thermal analysis of the LiCl–LiBr–Li<sub>2</sub>SO<sub>4</sub> system

The LiCl–LiBr–Li2SO4 system was studied by differential thermal analysis (DTA) and differential scanning calorimetry (DSC). Analysis of the phase complex revealed that the liquidus surface of the system consists of Li2SO4 crystallization fields and a continuous series of LiClxBr1–x solid solutions. The composition of the minimum point M 457 is determined, in eq. %: LiCl – 18; LiBr – 42; Li2SO4 – 40. The crystallization temperature is 457°C, and the specific enthalpy of the phase transition is 248.1 ± 7.5 J/g. To identify phase reactions in the LiCl–LiBr–Li2SO4 system, a 3D spatial model was constructed and a separable model of the crystallization volumes of the system phases was modeled, and also, as a demonstration of the possibilities of using a 3D model, a diagram of the material balance of equilibrium coexisting phases was constructed for an arbitrarily selected figurative point of the system under study. To build the model in the COMPAS-3D program, data on melting temperatures and eutectic compositions of smaller–dimensional faceted elements were used, as well as on the polythermal sections of the three–component LiCl–LiBr–Li2SO4 system experimentally studied in the work.