Preparation of crystalline rare earth carbonates with large particle size from the lixivium of weathered crust elution-deposited rare earth ores

Crystalline rare-earth (RE) carbonates having large particle size were prepared from the lixivium of weathered crust elution-deposited rare-earth ores using the precipitation method with ammonium bicarbonate as the precipitant. Their chemical composition was studied using elemental and thermogravimetric analyses (TGA), and their structure and morphology were characterized using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results demonstrate that the crystalline rare-earth carbonate is a hydrated basic carbonate or oxycarbonate and not astable intermediate carbonate in the process of thermal decomposition. The particle size of crystalline rare-earth carbonates with large particle size is in the range of 50–200 µm. With an RE2O3 content of up to 95wt%, the quality of crystalline rare-earth carbonates is higher compared to the Chinese National Standard (GB/T 28882-2012). The quality of the product is superior to the Chinese National Standard.