Synergetic recovery of rutile and preparation of iron phosphate from titanium-extraction tailings by a co-leaching process

This study presents a compelling, eco-friendly methodology for extracting valuable materials from titanium extraction tailing (TET) discharged from the reduction rust process. The process efficiently separates titanium and iron by utilizing a co-leaching technique with sulfuric and phosphoric acids. This method results in a high-grade titanium dioxide (TiO2) with a purity of 61.57 % and an iron leaching rate surpassing 96 % under the optimal conditions of the liquid-to-solid ratio of 4:1, a leaching temperature of 70 °C, and a specific phosphoric acid to iron molar ratio is 1.1. The subsequent refinement phase involves adjusting the pH to 2.0 using ammonia, coupled with controlled precipitation temperature and ageing time, leading to the production of battery-grade iron phosphate (FePO4) with a purity of 98.82 %, in line with the stringent HG/T4701-2014 standards. The material's phase analysis and morphological characterization confirm its high crystallinity and minimal impurity levels. Moreover, the co-leaching approach facilitates magnetite dissolution, effectively enriching the rutile content in the leach residue and concurrently minimizing the formation of ammonium sulfate salts, thereby enhancing the purity of the iron phosphate. These technological advancements contribute to resource recovery research and offer new avenues for industrial material production, laying a solid foundation for sustainable industrial applications.