红土镍矿非自由水脱除热分析动力学

在升温速率分别为10、15、20和25℃·min-1的条件下，利用差示扫描量热仪对红土镍矿非自由水脱除过程进行了测试.针对测试数据，分别采用Flynn-Wall-Ozawa ( FWO)法、胡荣祖-高红旭-张海( HuGZ)法、Boswell法、Starink法、Friedman-Reich-Levi ( Friedman)法等不同的转化率法计算其活化能，利用Malek法计算指前因子( A)以及确定机理函数，最后利用所得的动力学公式推导出等温下反应进度与时间的关系并对不同温度下的能耗进行分析比较.红土镍矿非自由水脱除过程的平均活化能为181.50 kJ·mol-1；指前因子lnA为21.95 min-1；机理函数符合Z-L-T方程，即脱除过程为三维扩散控制机制；干燥温度越高所需的平均功率越小.

Thermal analysis kinetics of non-free water removal in nickel laterite

Differential scanning calorimetric ( DSC) data during non-free water removal in nickel laterite were determined with a NETZSCH STA 449C thermal analyzer. Experiments were carried out at four heating rates of 10, 15, 20 and 25℃·min-1 . According to these DSC curves at different heating rates, the activation energies were calculated by five different calculation methods of conversion rate, namely the Flynn-Wall-Ozawa ( FWO) , Hu-Gao-Zhang ( HuGZ) , Boswell, Starink, and Friedman-Reich-Levi ( Friedman) methods. The pre-exponential factor ( A) and the most probable mechanism function were determined by the Malek method, then the relationship between reaction degree and time under an isothermal condition was derived and the energy consumptions at different temperatures were analyzed and compared. The average activation energy of non-free water removal in nickel laterite is 181. 50 kJ· mol-1. The average lnA is 21. 95 min-1. The most probable mechanism function fits the Zhuralev- Lesokin- Tempelman (Z-L-T) equation well. The non-free water removal is controlled by three-dimensional diffusion. The average power decreases with increasing temperature.