The TREESURE project, a Franco-Australian collaboration between CEA/DES/ICSM and Lynas Rare Earths, aims to optimize the processing of monazite ores for rare earth extraction. In this context, this 18-month postdoctoral position will focus on determining key thermodynamic data (Cp, ?rH) that are currently lacking, using Calvet calorimetry. The study will progress from model phosphate and sulfate compounds to complex multicationic systems. These simulated ores, representative of the Mount Weld mine (Australia), will then be compared with actual concentrates supplied by Lynas. Calorimetric measurements will be combined with structural and physicochemical characterizations to gain a better understanding of the mechanisms involved in sulfuric acid conversion. The resulting data will directly feed into the industrial models developed by Lynas. Ultimately, this work aims to reduce energy and acid consumption in mineral processing while maximizing rare earth extraction efficiency.