Preparation of Cerium-rich Rare Earth Oxide Nanoparticles from Bastnaesite Concentrate

摘要

Cerium-rich rare earth oxides nanoparticles were extracted from bastnaesite concentrate by first leaching, alkali fusion with NaOH, and second leaching process. The effects of the hydrochloric acid concentration, mass ratio of solid to liquid, leaching temperature of the leaching process, and the NaOH amount, roasting temperature and roasting time of alkali fusion process were systematically studied by X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD) and transmission electron microscope (TEM) analysis. The optimum parameters of the leaching process were 2 mol L~(-1)HCl solution, solid to liquid mass ratio 1: 5 and 75°C, respectively. Non-rare earth impurities could be effectively removed by roasting the first sludge with 30wt.% NaOH. The grade of total rare earth oxides and the purity of CeO_2 in the final product were 96.99% and 78.73%, respectively, which were improved by 10.62% and 5.73% than that of one step leaching. The cerium-rich rare earth oxides powder showed a major phase of ceria, with particle size distribution of 20～100nm according to TEM.