The Study on Oxidation Characteristics and Spontaneous Combustion Micro-Structure Change of Unloading Coal under Different Initial Stress

Abstract

ABSTRACT To study the oxidation characteristics and spontaneous combustion micro-evolution characteristics of coal unloaded under different initial stress, in this paper, a comparative study on the micro-oxidation characteristics of the raw coal samples with easy spontaneous combustion and the unloaded coal samples under different initial stress was carried out by using the temperature-programmed experiment, the three axial creep test of coal rock, and the mercury injection experiment. The findings indicate that in the macroscopic aspects, the unloaded coal under different initial stresses is easier to oxidize than the raw coal sample. The CO production–strain curve of the experimental coal samples is similar to the axial stress–strain curve; when the initial stress reaches 25 MPa, the coal sample is in the stage of strain softening and the oxidation capacity of coal sample is the strongest. The infrared spectra of FTIR are analyzed, and the dynamic changes characteristics of microactive groups such as aromatic hydrocarbons, aliphatic hydrocarbons, and oxygen-containing functional groups under different initial stress are mastered. The microscopic spontaneous combustion mechanism of unloading coal under different stress is obtained.