| Abstract Scope |
Lithium sulfate leachates from mineral processing, such as montebrasite treatment, commonly contain co-dissolved Al³⁺, Mg²⁺, and Ca²⁺ that compromise battery-grade product purity. This work presents a selective purification route using Na₃PO₄ precipitation to remove multivalent impurities while retaining lithium in solution, followed by phosphate-mediated recovery of high-purity LiH₂PO₄. A quadratic response surface model evaluated phosphate dosage, pH, temperature, and reaction time, showing strong predictive capability (R² = 0.90–0.96) with pH and dosage as dominant, synergistic variables. Under optimized conditions, removal reached 99.9% of Al, 96.2% of Mg, and 98.9% of Ca, with only 5.01% lithium loss. Purified lithium was recovered as crystalline Li₃PO₄ and protonated to phase-pure LiH₂PO₄, confirmed by XRD, with overall lithium recovery exceeding 94%. The route offers a scalable purification strategy for lithium recovery circuits. |