Using inverting CO critical value to predict coal spontaneous combustion severity in mine gobs with considering air leakages - A case study

The mined-out space in underground coal mines increases due to the mining face advances. The airflow continuously could enter the mine gob via the air leakage channels, which may cause the coal in gob spontaneously ignite and combust. The gob is not accessible for personal direct gas composition measurement due to rock collapses and blockages. Thus, it is difficult to monitor its spontaneous combustion condition timely, which leads to the blindness of developing spontaneous combustion prevention measures. Therefore, it is important to understand the status of spontaneous combustion of residual coal in the gob in time. To more accurately predict the coal spontaneous combustion in gobs, this paper proposes a new model to predict the burning state of coal in the gob by using the gas-CO generated by coal spontaneous combustion with considering the action of air leakages in the gob. Then the reflected CO critical value in the corner of the longwall face in return airflow side can be derived. An example application is also presented in this paper, which shows that the proposed method could better reflect the spontaneous combustion state of gob, and the derived critical value can be used as an early warning message to prevent the coal spontaneous ignition in the gob and reduce the probability of coal spontaneous combustion accidents.