Recovery of lanthanum and cerium from rare earth polishing powder wastes utilizing acid baking-water leaching-precipitation process

Abstract

A new approach to recover lanthanum and cerium from rare earth polishing powder wastes has been developed in this study. Lanthanum and cerium oxides in the raw materials were converted to sulfate by concentrated sulfuric acid baking at 300 °C, and the roasted product was leached with water at 25 °C for 2 h. Under the optimal conditions, nearly all the rare earth elements in the liquor was precipitated as La(III) and Ce(III) oxalate deca-hydrate with oxalic acid. The oxalate precipitate was then calcined at different temperature (550–950 °C) to prepare the final product- La2O3 and CeO2. X-ray diffraction results provide detailed phase transformation information of rare earth elements during the recovery process. The final product composed of 34.18% La2O3 and 65.66% CeO2 was given the composition and structure analysis. During the whole process, the yield of La and Ce were 99.39% and 89.02%, respectively.