The kinetic mechanism of magnesite thermal decomposition under N2 and CO2 atmospheres
In response to the challenges posed by the high energy consumption,poor environmental performance,and low production efficiency associated with the lightly burnt magnesia rotary kiln,researchers have introduced a promising solution in the form of a new calcination furnace that exhibits substantial energy-saving potential.However,to further enhance the effectiveness of this innovative furnace and refine the production processes,it is imperative to gain a more comprehensive understanding of the thermal decomposition kinetics of magnesite.This research is rooted in an analysis of the gas phase composition within the furnace during the actual production of magnesite calcination.Employing the TG-DTA thermal analysis technique,the study investigates the thermal decomposition kinetics of magnesite under N2 and CO2 atmospheres.The findings reveal that under N2 atmosphere,the thermal decomposition kinetics of magnesite involves two distinct stages:the phase boundary reaction shrinkage columnar mechanism and the random nucleation and growth mechanism.On the other hand,under the CO2 atmosphere,the kinetics process consists of three stages with two mechanism modes,including the random nucleation and growth mechanism,as well as the phase boundary reaction shrinkage spherical mechanism.Furthermore,the study's analysis indicates that the impact of CO2 on the thermal decomposition process of magnesite is twofold.On one hand,CO2 raises the activation energy of the reaction,resulting in an elevated decomposition reaction temperature.Conversely,CO2 also has the capacity to induce the nucleation and growth of the product CO2,thereby making the decomposition reaction rate more sensitive to the change of temperature.The present work's elucidation of the kinetic mechanisms governing magnesite thermal decomposition under N2 and CO2 atmospheres not only provides valuable data to support the optimization of the new type of calcination furnace,which has important engineering application prospects,and can also provide reference value for further research.Expanding upon these insights through further research and development endeavors holds the potential to drive substantial advancements in the field of magnesite processing and contribute to the overall sustainability of industrial processes.
thermal decomposition of magnesitelight calcined magnesiakinetic mechanismMalek method
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