Leaching Behaviour and Kinetic of Light and Heavy Rare Earth Elements (REE) from Zircon Tailings in Indonesia

Zircon tailings containing rare earth metals are one of the alternative raw materials from secondary sources in Indonesia. The objective is to determine the effects of several operating conditions in the leaching process. Under specified leaching conditions including 2 M hydrochloric acid concentration, 10 g/100 mL solid-liquid ratio, and a temperature of 80 degrees C, the optimum rare earth metal leaching recovery was obtained. Under these conditions, as much as 60%, 74%, and 65% for cerium, lanthanum, and neodymium can be leached, respectively. With the same conditions, HREE was leached as much as 71%, 61%, and 60% for erbium, gadolinium, and samarium. The leaching process was described using the kinetic model known as the Zhuravlev-Leshokin-Templeman model. Activation energy values for light and heavy rare earth element leaching were found to be 25.31 kJ/mol and 7.05 kJ/mol, respectively.