关键词: 菱镁矿;动力学;热重分析;活化能;反应机理函数

Abstract: Decomposition kinetics of different particle size magnesite was investigated by using thermogravimetric (TG) analysis.The activation energy and pre-exponential factor (A) of the decomposition from different particle sizes magnesite were calculated according to the Flynn-Wall-Ozawa method.Determine the optimal decomposition mechanism based on the principle of maximum correlation coefficient by using Thermo-kinetics software fitting to 5 most possibility kinetic mechanism functions.The research results indicate that the activation energy of thermal decomposition of magnesite decreases with the increasing of particle size.With the increasing of particle size of magnesite the mechanism of thermal decomposition process is influenced by the chemical reaction and gradually changed to the heat transfer inside the particle and diffusion of CO2.The most probable reaction mechanism of the thermal decomposition process is a three-dimensional boundary reaction (R3).The kinetic equation is as follows:G(α)=1-(1-α)1/3.

Key words: magnesite;kinetics;thermogravimetry analysis;activation energy;reaction mechanism function