主要载金硫化物黄铁矿的热分解动力学特性

Characteristic of thermal decomposition kinetics of main gold-bearing sulfides pyrite

采用TG-DSC热分析技术,在不同升温速率条件下对主要载金硫化物黄铁矿的热分解动力学进行研究,并采用SEM对反应前后的黄铁矿微观结构进行分析。结果表明：黄铁矿热分解的温度区间为400～800℃,质量损失率保持在26%左右;随着升温速率的增大,TG曲线向高温区偏移,即得到相同转化率所需的温度越高,其最大反应速率的温度范围为600～700℃。采用Kissinger法和Ozawa-Doyle法求得黄铁矿热分解反应的活化能E和指前因子A分别为259.23 k J/mol和1×1014.67。根据Coats-Redfern方程和常见的热分解机理函数对热重分析数据进行线性拟合,采用Malek法进一步确定了黄铁矿的热分解过程符合Mample单行法则,其反应机理为随机成核和随后生长,并获得了热分解反应的微分方程。

Thermal decomposition kinetics of main gold-bearing sulfides pyrite was investigated by TG-DSC thermal analysis at different heating rates. The microstructures of pyrite before and after decomposition were analyzed by SEM. The results show that the thermal decomposition temperature of pyrite is between 400-800 ℃. The mass loss rate is approximately 26%. The TG curves move in the direction of high temperature with increasing the heating rate. This means that the same conversion can be gotten at higher temperature. The temperature range of the maximum pyrite thermal decomposition reaction rate of pyrite is between 600-700 ℃. The apparent activation energy E and pre-exponential factor A were calculated by Kissinger and Ozawa-Doyle methods, and the values are 259.23 kJ/mol and 1×10^14.67, respectively. According to Coats-Redfern equation, linear regressions were carried out by common mechanism functions of thermal decomposition. It is defined that the thermal decomposition process of pyrite conforms to the Mample principle by Malek method, and the corresponding mechanism is the random nucleus and the consequent growth. The differential equation of thermal decomposition reaction was deduced as well.