This study investigates the influenceMontebrasite ore ofLeaching roastingPhosphorus transformation temperature on phosphorus transformation and leachingLeaching behavior during sulfuric acid roasting of Montebrasite oreMontebrasite ore with formula LiAlPO4(OH)0.62F0.38. Montebrasite poses a persistent challenge due to the strong coupling between phosphorus (P) and aluminum (Al), which complicates selective recoverySelective recovery during conventional processingProcessing. Sulfuric acid (H2SO4) roasting experiments were performed across a temperature range of 140–900 °C with a fixed acid dosage of 50% ore mass, followed by water leachingWater leaching at 80 °C. Thermodynamic modelingModeling (100–200 °C, 0.5 and 2.0 mol H₂SO₄ dosage) was employed to predict phase stability and transformation pathways, while experimental validation was carried out using ICP-OES, and X-ray Diffraction (XRD) analyses. The results reveal a temperature-dependent shift in phosphorus speciation, at low roasting temperatures (<300 °C), P is predominantly released as soluble H3PO4, enhancing its leachability but accompanied by significant co-dissolution of Al. Above 600 °C, however, P reacts with Al-bearing species to form insoluble AlPO4, resulting in sharp suppression of P extractionExtraction (<0.5% at 800 °C). In contrast, lithiumLithium (Li) is stabilized as soluble Li2SO4 above 700 °C, maintaining high extractionExtraction efficiency (>93%). These findings highlight the dual role of roasting temperature: low temperatures favor P solubilization but reduce selectivity, while high temperatures suppress P extractionExtraction yet enable nearly selective lithiumLithium recovery. The study provides a mechanistic understanding of phosphorus-aluminum coupling during sulfuric acid roasting and offers critical insights for designing optimized processingProcessing strategies to balance selective Li recovery with efficient P separationSeparation in Montebrasite oreMontebrasite ore.