Analysis of Occurrence States of Rare Earth Elements in the Carbonatite Deposits in China

Rare earth elements (REEs), as necessary elements in many industries, have driven increased demand for mineral exploitation. However, understanding the occurrence states of REEs is crucial for their extraction. Therefore, this work primarily investigated the differences in the occurrence states of REEs and the thermal decomposition behavior of carbonatite rare earth deposits in China using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray powder diffraction, and X-ray photoelectron spectroscopy. The results showed that the bastnaesite concentrate from the M deposit in southwestern China (referred to herein as B-ore), contained REEs accounting for 53.59%, and was associated with small amounts of wulfenite, barite, and iron ore. In contrast, the contents of REEs in the raw ores of N deposit in northern China (referred to herein as R-ore) was relatively low (3.71%), but were also enriched in Fe. R-ore consisted of small particle, with 32.44% sized between 0.075 and 0.11 mm, and 26.38% below 0.075 mm. The contents of Fe, La, and Ce in these smaller particles were higher than those of larger particles. Fe might be substituted with Ce, La, and other REEs in magnetite crystals, forming isomorphic structures. This research was expected to provide assistance in the efficient extraction of REEs from carbonatite deposits.