Leaching Kinetics of Rare Earth Elements in Phosphoric Acid from Phosphate Rock

Phosphate rock has been considered as one of the most significant secondary rare-earth resource, and utilization rare earth elements (REEs) in phosphate attracted increasing attention. In this study, leaching kinetics REEs from a ore China was studied with variation temperature phosphoric acid concentration under conditions: ratio liquid to solid 12 mL/g, stirring speed 120 r/min, particle size ?0.074 mm amounts 61.1%. The results suggest that there were two distinct stages process both followed shrinking core model. At fast reaction stage, semi-empirical equation describing 1 ? 3(1 ?)2/3 + 2(1 ?) = 1.885CH3PO40.89exp(?11220/8.31T)t. for slow stage 0.299CH3PO42.50exp(?18720/8.31T)t. Using model time-to-a-given-fraction method, we found rate controlled by product layer diffusion, diffusion chemical determined stage.