The auto-oxidation characteristic of coal at different stages of the low-temperature oxidation process

Abstract

The spontaneous combustion in the mining gob are often caused by the low-temperature oxidation of coal, and the low-temperature oxidation process has a long process leading to different characteristics in each stage, which brings great difficulties to the prevention and control of coal spontaneous combustion in the underground mining gob. Therefore, this article investigated the oxidation characteristics of coal at different stages of the low-temperature oxidation, mainly including: analyzing the changes in radical concentration and g factor based on electron spin resonance (ESR) experiments, studying the variations in coal temperature by using the programmed temperature controller and analyzing the characteristics of gas products and oxygen consumption by using the gas chromatograph. And the degree of auto-oxidation of coal was characterized by the difference between dry air and nitrogen conditions during the constant temperature period. The results showed that when the constant temperature reached 130 ℃, the coal began to exhibit auto-oxidation characteristics, while when the constant temperature reached 180 ℃, the auto-oxidation phenomenon of the coal significantly intensified, the types and content of radicals rapidly grew, the coal temperature significantly rose, and the oxygen consumption rapidly increased, while releasing a large amount of CO and CO2. And the relationship between the spontaneous oxidation ability of coal radicals and the temperature change of coal during constant temperature was obtained. The conclusions obtained provide theoretical guidance for the safety and clean production of coal resources in mines, as well as the prevention and control of coal spontaneous combustion fires.