机械力活化诱导硫化矿石自燃的热分析动力学

Thermal analysis kinetics of mechanically activated sulfide ores for spontaneous combustion

为揭示硫化矿石在经历机械力活化后的氧化自燃特性,运用热分析技术表征矿样在不同功率(100~450r/min)、不同料球比(1:3~1:12)条件下活化后的热分解动力学参数;采用X射线衍射技术对活化矿样进行线形分析,比较矿样活化前后的晶格畸变率和晶块尺寸。结果表明:硫化矿石在530~640℃温度区间的氧化热解过程符合一维扩散反应动力学机制;其表观活化能随着球磨功率、料球比的增加而降低,呈现出较好的一致性;矿样在未活化、200 r/min、350 r/min活化条件下的表观活化能依次为258.93、181.34、150.97 k J/mol,对应的指前因子分别为2.35×10^(18)、1.45×10^(13)和1.60×10^(11);矿样在料球比为1:3、1:8活化条件下的表观活化能依次为240.57、150.97 k J/mol,指前因子分别为1.58×10^(17)、1.60×10^(11);硫化矿石的表观活化能的降低与活化矿样晶格畸变率的增大及晶块尺寸减小存在一定的相关性,进而容易引发自燃。

In order to uncover the intrinsic influence of mechanical activation on property of oxidation and spontaneous combustion of sulfide ores, the thermal analysis technique was used to characterize the kinetic parameters of samples under different mechanical powers（100-450 r/min） and different material-ball ratios（1：3-1：12） after mechanical activation. Meanwhile, the X-ray diffraction analysis was used to obtain the lattice distortion rate and block size after mechanical activation. The results show that the kinetics reaction process of the sample complies with the diffusion one-way transport mechanism under the temperature between 530 to 640 ℃. By the increase of mechanical power and material-ball ratio, the apparent activation energy of samples reduces with good consistency. The corresponding activation energy values calculated under non-activated, 200 r/min, 350 r/min are 258.93, 181.34 and 150.97 k J/mol. and the pre-exponential factors are 2.35×10^18, 1.45×10^13 and 1.60×10^11, respectively. Meanwhile, the corresponding activation energy values calculated under 1：3, 1：8 are 240.57, 150.97 k J/mol, respectively, and the pre-exponential factors are 1.58×10^17, 1.60×10^11, respectively. The reduction of apparent activation energy of mechanically activated sulfide ores is related to the increasement of lattice distortion rate and reduction of the block size, so, it can lead to spontaneous combustion under proper environmental conditions.