Frictional Ignition of Methane by Continuous-Mining Machines in Underground Coal Mines

摘要

This report presents information on frictional methane ignitions associated with continuous miners. Data indicate a gradual increase in frictional methane ignitions over the 6-year period 1971 through 1976. Ninety percent of these ignitions are attributed to continuous-mining machines. Factors affecting such frictional ignitions are analyzed and recommendations are submitted for reducing their incidence: make proper use of diffuser fans, line curtains, check curtains, and ventilation tubing or combinations thereof; minimize obstructions to air flow such as coal piles and secondary loading behind continuous miners; minimize air leakage by proper construction and maintenance of ventilation controls; and utilize Venturi principle of water sprays to increase flow of air between face and continuous miner cutter head. The following additional safety measures may aid in preventing and/or quenching frictional ignitions: reduce speed of rotation of cutting heads; insure adequacy of water flow through spray heads to facilitate cooling of cutter bits; exercise caution with respect to possible methane liberations while mining through clay veins and taking roof or bottom rock; replace dull and broken cutter bits promptly; insure proper functioning, maintenance, and calibration of methane monitors; locate methane monitors as near as practicable to the front of the continuous mining machine; and fromote and encourage developments in technology leading to a system to detect and suppress methane ignitions caused by face-cutting equipment. (ERA citation 08:048558)