不同粒度煤低温氧化中自由基变化的实验研究

Experimental study on change behind free radicals during low temperature oxidation of coal with different particle sizes

为揭示不同粒度煤低温氧化过程中自由基的变化特征对应煤自燃的微观变化过程,利用电子自旋共振波谱仪,以山脚树矿的1/3焦煤和肥煤为研究对象,研究不同粒度煤样低温氧化过程自由基参数的变化规律。结果表明:在整个升温过程中,g因子值在2.001542~2.002050之间,变化不大,煤样的粒度越小,g因子值越大;线宽ΔH随温度的升高持续降低,粒度为0~0.075 mm的煤样在升温区间内由4.47 Gs降至3.14 Gs,降幅最大;不同粒度的煤低温氧化过中自由基浓度随温度的升高而不断增加,呈阶段性变化,110℃之后,煤氧复合速度加快,自由基浓度迅速增长,110~250℃升温范围内,0~0.075 mm煤样自由基浓度增长速率为7.23×10^15℃-1。

This paper is an effort to reveal the law of how the change characteristics behind free radicals corresponds to the microscopic change process of coal spontaneous combustion during low temperature oxidation of different particle sizes of coal.The study investigates the law underlying the changes of free radical parameters during low temperature oxidation of coals with different particle sizes by taking1/3 coking coal and fat coal of Shanjiaoshu Mine as a research object and using electron spin resonance spectroscopy.The results show that during the whole heating process,the g factor of coals with different particle sizes ranges between 2.001542 and 2.02050,with little change,suggesting that the smaller the particle size of the coal sample,the greater the g factor value;along with the increase of temperature comes a continuous decrease in the linewidth△H,resulting in the largest decrease from 4.47 Gs to 3.14 Gs in coal samples with 0-0.075 mm particle size in the heating range;and the free radical concentration in low temperature oxidation of coal with different particle size experiences a continuous increase with the increase of temperature,showing stage variations from a faster recombination rate of coal and oxygen and therefore a rapid increase in the free radical concentration after 110℃to the increase rate of 7.23×10^15℃-1 in free radical concentration in coal samples varying from 0 to 0.075 mm within the temperature range of 110-250℃.