Abstract: 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.

Key words: thermal decomposition of magnesite, light calcined magnesia, kinetic mechanism, Malek method

摘要： 为解决轻烧氧化镁回转窑能耗高、环保性差、生产效率低的问题，研究者提出了新型焙烧炉，其具有良好的节能潜力，为了进一步优化结构及生产过程，需要更深入地了解菱镁矿的热分解动力学特性。本研究基于菱镁矿焙烧工业实际生产中炉窑内气相成分考虑，采用TG-DTA热分析技术研究了菱镁矿在N2和CO2气氛下的热分解动力学行为。结果表明，菱镁矿在N2气氛下的热分解动力学过程先后经历相边界反应收缩柱状机理和随机成核生长机理两个阶段，而CO2气氛下的动力学过程包含三个阶段，涉及随机成核生长机理和相边界反应收缩球状机理两种机理模式。进一步分析认为CO2对菱镁矿热分解过程的影响具有双面性，一方面使反应活化能增大，增高分解反应温度；另一方面能诱导产物CO2成核生长，使分解反应速率对温度的变化更加敏感。本研究揭示了N2和CO2气氛下菱镁矿热分解的动力学机理，对优化新型焙烧炉提供了数据支持，具有重要的工程应用前景，也能够为进一步的研究提供参考，推动菱镁矿加工领域的技术进步和持续性发展。

关键词: 菱镁矿热分解, 轻烧氧化镁, 动力学机理, Malek法