Thermal decomposition mechanism of low-content-fluorite Bayan Obo rare earth concentrate roasted with sodium carbonate and its consequent separation study

Dan Zou¹，Ji Chen¹，Jiashi Hu²，Kai Li^1,3，Deqian Li¹

1. State Key Laboratory of Rare Earth Resources Utilization,Changchun Institute of Applied Chemistry,Chinese Academy of Sciences2. College of Chemistry and Chemical Engineering,Inner Mongolia University3. University of Science and Technology of China

摘 要：Thermal decomposition and phase transformation for the mixture of Bayan Obo rare earth concentrate（BORC） and sodium carbonate（Na₂CO₃） roasted at different temperatures with weight ratio of 100:20 were studied in detail in our study.The aim of our study is to reveal the nature of roasting reaction between BORC and Na₂CO₃ and thus providing a new method for processing BORC.The results indicate that BORC can be decomposed completely with Na₂CO₃ at around 600℃ after 3 h.During the calcination process,Ce_0.5Nd_0.5O_1.75,NaF,Na₃PO₄,and a rare earth double phosphate phase Na₃RE（PO₄）₂ are formed after the decomposition of BORC with Na₂CO₃.In addition,the thermal decomposition mechanism is determined in the paper.Based on these facts,a clean technique processing BORC was developed.And a CeF₃ powder,whose composition was measured and stability was also evaluated,was obtained for some potential application from the new technique.This research is of significance in terms of the Na₂CO₃-roasting BORC solid reaction study and sheds a light on a potential clean technique for BORC.

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