硫化矿石诱导自燃过程及分阶段混沌特征

Induced spontaneous combustion process and chaotic characteristics by stages of sulfide ores

为揭示硫化矿石自燃过程的混沌特征,以从某硫铁矿采集的矿石样品作为实验材料,室内开展矿石诱导自燃实验,进而集成小波技术和混沌动力学理论对诱导自燃过程中的不同阶段进行了研究。研究结果表明:8个矿样的自燃点温度分别为408,385,437,334,374,365,366和380℃,在正常采矿条件下矿石不易发生自燃;矿样的自燃过程分为3个阶段,依次为自燃孕育期、自燃发展期和临近自燃期,其平均升温率分别为1.0,2.0和4.2℃/min;随着时间的推移,矿样自燃过程的最大Lyapunov指数整体呈逐渐增大趋势,3个阶段的平均值分别为0.001 5,0.002 0和0.005 0,这是自热反应复杂剧烈程度的一种客观反映;随着矿样自燃点温度的升高,其临近自燃期的最大Lyapunov指数整体呈逐渐减小趋势。因此,可基于该阶段的最大Lyapunov指数来定性判定矿样自燃点温度。

To reveal chaotic characteristics of the spontaneous combustion process of sulfide ores, ore samples from a pyrite mine were taken as experimental materials and induced spontaneous combustion experiment was carried out in laboratory. Furthermore, different stages during the induced spontaneous combustion process were studied by integrating wavelet technology and chaotic dynamics theory. The results indicate that ignition point temperatures of the eight kinds of ore samples are 408, 385, 437, 334, 374, 365, 366 and 380 ℃ respectively indicating that they are difficult to combust spontaneously under normal mining conditions. Spontaneous combustion process of ore samples includes three stages： incubation stage of spontaneous combustion, development stage of spontaneous combustion and the approaching stage of spontaneous combustion. The average temperature rising rates of the three stages are 1.0, 2.0 and 4.2 ℃/min, respectively. With the lapse of time, the maximum Lyapunov exponent of spontaneous combustion process increases gradually. And the average values of the three stages are in order of 0.001 5, 0.002 0 and 0.005 0, which is an objective reflection of complexity and intensity for self-heating reaction. The maximum Lyapunov exponent for the approaching stage of spontaneous combustion decreases gradually as ignition point increases. Therefore, ignition point of ore samples can be determined qualitatively based on the maximum Lyapunov exponent for the approaching stage of spontaneous combustion.