| Description |
Coal has an inherent tendency to combust in presence of oxygen. This phenomena is termed as spontaneous combustion of coal. Pressure balancing is a tool that can be used to solve the problem. Pressure balancing is the technique of equalizing pressure differentials between two areas such as mine gob and its surroundings so that the flow of air or the ingress of oxygen to the cave area is reduced or eliminated. Critical factors affecting spontaneous combustion of coal are thoroughly evaluated. These factors include not only the quality of coal but also geological features and mining methods used to extract the coal. The propensity of coal to self-heating can be determined by using a software such as SPONCOM developed for this purpose. There are two types of pressure balancing namely passive and active. Passive balancing is desirable, as it can be achieved using passive means such as regulators and fans. Dynamic pressure balancing is another type of passive pressure balancing in which chambers are established and pressurized using airflow existing in the mines. If a passive balancing technique is not adequate, then an active pressure balancing could be used. Inert gas is used to pressurize the chamber in an active pressure balancing method. The University of Utah ventilation laboratory model was upgraded to include an atmospheric monitoring system. The model was used to conduct several experiments to equalize pressure differential across the simulate gob. All the vital ventilation control parameters can be observed and recorded using this system. Furthermore, a sub-routine was developed to accomplish the pressure balancing system automatically. Three underground coal mines have been visited as part of this study: one room and pillar and two long wall mines. The objective was to conduct pressure-quantity surveys, and to determine the pressure differentials across the stoppings used to isolate the worked-areas. The results of the surveys conducted in the room and pillar mine are presented and discussed in this study. The study concludes with an inventory of hazards related to spontaneous combustion, control measures, and risk analyses to identify the critical factors. |
