关键词: 菱镁矿　, 等温动力学　, 悬浮煅烧　, 粒度

Abstract: To investigate the thermal decomposition reaction mechanism of fine magnesite in a suspended state and to provide a theoretical basis for optimizing the suspension calcination process,this study employed an online gas composition a nalysis system to conduct an indepth investigation into the reaction kinetics during the thermal decomposition of fine magnesite. The results indicate that with increasing temperature,the peak reaction rate of magnesite particles gradually rises,and the time required to reach the peak is significantly shortened.The reaction fraction and reaction rate of magnesite with different particle sizes exhibit similar trends.Integral kinetic analysis reveals that for magnesite particles with 60% passing 325 mesh,the ther mal decomposition kinetics at low temperatures follow the model G(α) =1-(1-α)1/3,with an apparent activation energy of 87.04 kJ/mol;At high temperatures,the kinetic model conforms to G(α)=[1-(1-α)1/3]2,with an apparent activation en ergy of 72.08 kJ/mol.For magnesite particles with 90% passing 325 mesh,the thermal decomposition kinetics at both low and high temperatures fit the model G(α) =1-(1-α)1/3,with activation energies of 107.58 kJ/mol and 76.79 kJ/mol,respec tively.The variation in kinetic models under different conditions is essentially attributable to the competition between the inter facial chemical reaction rate and the CO2 product diffusion rate,which is jointly governed by temperature and particle size.As the particle size increases,the rate-controlling mechanism of magnesite thermal decomposition shifts from interfacial chemical reaction control to intraparticle diffusion control.