毒重石在700～1000℃下的热分解动力学模型研究

本文采用DTA-TG热分析及动力学计算对四川万源庙子的毒重石贫、富矿在700~1000℃下的热分解行为及其机理进行研究。万源庙子的毒重石贫矿在720~815℃,815~910℃发生分解,第一步由n为1的成核与生长机制控制,热分解机制方程式为:-ln(1-a),E为261.9kJ/mol,A为3.8788×1010,第二步在由三维扩散,3D(球对称)机制控制,热分解机制方程式为:1-(1-a)1/3]2,E为265.2kJ/mol,A为1.5498×109。富矿在700~1000℃也分两步,第一步在760~840℃;第二步在850~980℃,此两步被分解物及分解产物同贫矿一样,富矿第一步是界面收缩的圆柱形对称机制控制,热分解机制方程式为:1-(1-a)1/3,E为206.1kJ/mol,A为4.7042×105。富矿第二步是以收缩的圆柱形对称和三维扩散,3D(圆柱形对称)的机理联合控制。

KINETIC MODEL STUDY ON THE DECOMPOSITION OF WITHERITE AT 700～1000℃

The decomposition behavior and mechanism of low-grade and high-grade witherit from Sichuan Wanyuan miaozi are studied by using thermal analysis and kinetics compute in this paper.The low-grade witherit of Wanyuan miaozi decomposed at 720～815℃ and 815～910℃.The first step of decomposition was controlled by nuclear producing and growing process(n=1),the decomposition mechanism may be expressed as follows:-ln(1-a),E=261.9kJ/mol,A=3.8788×10~(10).The second step of decomposition was controlled by three-dimensional diffuse(ball symmetry),the decomposition mechanism may be expressed as follows: 1-(1-a)~(1/3)]~2,E=265.2kJ/mol,A=1.5498×10~9.The high-grade witherit of wanyuan miaozi also decomposed at 760～840℃ and 850～980℃.The decomposed and decomposing matters of high-grade witherit were same as low-grade witherit,The first step of decomposition of high-grade witherit was controlled by boundary surface contraction(column symmetry),the decomposition mechanism may be expressed as follows: 1-(1-a)~(1/3),E=206.1kJ/mol,A=4.7042×10~5.The second step of decomposition was controlled by boundary surface contraction(column symmetry) and three-dimensional diffuse(column symmetry).