Kinetics of rare earth leaching from roasted ore of bastnaesite with sulfuric acid

Sulfuric acid leaching process was applied to extracting rare earth (RE) from roasted ore of Dechang bastnaesite in Sichuan, China. The effect of particle size, stirring speed, sulfuric acid concentration and leaching temperature on RE extraction efficiency was investigated, and the leaching kinetics of RE was analyzed. Under selected leaching conditions, including particle size (0.074-h0.100 mm), sulfuric acid concentration 1.50 mol/L, mass ratio of liquid to solid 8 and stirring speed 500 r/min, the leaching kinetics analysis shows that the reaction rate of leaching process is controlled by diffusion through the product/ash layer which can be described by the shrinking-core model, and the calculated activation energy of 9.977 kJ/mol is characteristic for a diffusion-controlled process.