Leaching kinetic study of sulfuric acid roasted mixed-type rare earth concentrate for reducing the solid-waste production and chemical consumption

Abstract The Baotou bastnaesite and monazite mixed rare earth ore is one of the most significant rare earth ore in the world and is mainly processed by the sulfuric acid roasting method. However, the high content of Fe and P in the leaching solution contributes to a large amount of radioactive precipitate waste produced in the purification process, and that causes the primary loss of rare-earth elements (REEs) and the environmental issue and safety concern. The goal of this paper is to reduce the solid-waste by improving the selective leaching efficiency of REEs based on a leaching kinetics study of REEs, Fe and P in the H2SO4 system. The experiments were carried out focusing on the effect of acidity, roasted concentrate particle size, temperature, and liquid-solid ratio on the leaching kinetics. The results indicate that the equilibrium leaching time of REEs (