稀土尾矿中氟碳铈矿分解反应动力学研究

Kinetic Analysis of Bastnaesite Decomposition in Bayan Obo Tailings

分解反应动力学可以深入分析氟碳铈矿分解反应过程,基于程序升温热重和质谱数据,采用Li Chung-Hsiung方法和Malek方法确定了氟碳铈矿分解反应过程的最概然机理函数、活化能和指前因子。热重实验结果表明,氟碳铈矿在空气和N_(2)气氛围下400~600℃温度范围内分解,空气氛围更有利于氟碳铈矿分解反应的进行,分解过程可用A模型很好地描述,即氟碳铈矿分解反应的速率控制步骤包含产物成核、核增长和核吸收长大。空气氛围下,氟碳铈矿分解反应过程活化能和指前因子分别为17.657~24.885 kJ·mol^(-1)和6.223~29.653 min^(-1);N_(2)气氛围下,氟碳铈矿分解反应过程活化能和指前因子分别为25.532~30.236 kJ·mol^(-1)和36.882~64.250 min_(-1),基于最概然机理函数、活化能和指前因子,建立了N_(2)气和空气氛围下的稀土尾矿中氟碳铈矿的分解反应动力学模型。

A theoretical basis and comprehensive information on the bastnaesite decomposition of the Bayan Obo rare earth tailings have been provided,on the basis of the kinetic analysis of the decomposition.The analysis was based on thermogravimetry and mass spectrum analyzer data.The most probable mechanism function,activation energy,and pre-exponential factor were determined by combining Li Chung-Hsiung method and Malek method.The TG results show that bastnaesite decomposes in the temperature ranging from 400 to 600℃in air and N_(2) atmosphere.Air atmosphere is more conducive to the decomposition of bastnaesite.The bastnasesite decomposition can be appropriately described by A model,in which the rate-determining step is governed by the relative rates of nucleation,nuclei growth,and nucleation absorption or a combination of the three processes.TG results revealed that parameters E and A of bastnaesite decomposition at different heating rates vary in the ranges 17.657~24.885 kJ·mol^(-1)and 6.223~29.653 min;in air,respectively,and 25.532~30.236 kJ·mol^(-1) and 36.882~64.250 min^(-1) in N_(2)atmosphere,respectively.By combining the data,kinetic model for bastnaesite decomposition is obtained.