Thermal Analysis of the LiCl–LiBr–Li2SO4 System

Abstract—The LiCl–LiBr–Li₂SO₄ system was studied by differential thermal analysis (DTA) and differential scanning calorimetry (DSC). Phase assemblage analysis showed that system’s liquidus surface consists of L-i₂SO₄ and LiCl_xBr_{1 – x} continuous solid solutions (CSS) crystallization fields. The composition of the minimum point M 457 in equivalent percent (equiv %) was determined as LiCl, 18; LiBr, 42; Li₂SO₄, 40. The crystallization temperature is 457°C, and the specific enthalpy of phase transition is 248.1 ± 7.5 J/g. A 3D model of the system was designed, and a disassemblable model of the phase crystallization volumes was designed in order to identify phase reactions occurring in the LiCl–LiBr–Li₂SO₄ system. A mass balance diagram of the coexisting equilibrium phases was designed for an arbitrarily selected figurative point of the system to demonstrate the power of the 3D model. The melting temperatures and eutectic compositions of lower-dimension boundary elements and polythermal sections of the LiCl–LiBr–Li₂SO₄ three–component system used to design the model in the COMPAS-3D program were experimentally studied in the work.