Plastic various splits in the mine, and 5,154,000 cubic feet of methane was being liberated from the mine every 24 hours. Stoppings, overcasts, and regulators were constructed of incombustible materials. impregnated line brattice was used to direct the air to the faces inby the last open crosscuts. Suitable preshift, onshift, and weekly examinations for methane and other hazards were made and the results were properly recorded. Tests for gas were made before electrically operated face equipment was taken inby the last open crosscut and frequently during the operation of such equipment in the face areas. Rock The mine surfaces in the 17 butt right section were wet. Dangerous accumulations of loose coal or coal dust were not observed. dust applications in the section appeared to be adequate. Electric power, at 250 volts direct current, was used to operate the electric face equipment. Electric face equipment used in the 17 butt right section consisted of a Joy (1-CM) continuous-mining machine, a Joy 11BU loading machine, and two Joy 10SC shuttle cars. The equipment was of the permissible type and in permissible condition at the time of this investigation. Trailing cables were fire resistant and provided with overload and short-circuit protection by automatic circuit breakers. The frame-ground conductors were continuous throughout. Firefighting equipment was adequate. Permissible electric cap lamps were used for portable illumination, and smoking was neither permitted nor practiced underground. Information for this report was obtained by an investigation at the scene of the occurrence and from statements made by Charles Robinson, continuous-mining-machine operator; Matt Sabula, roof bolter; and Martin Swarrow, loading-machine operator, all of whom were present when the ignition occurred. The last Federal inspection was completed May 16, 1969. DESCRIPTION OF OCCURRENCE Shortly after 4 p.m., Monday, May 26, the crew of the 17 butt right section left the Grimes portal and arrived on the section about 30 minutes later. John Knapik, Assistant Mine Foreman, made an examination of the section and found it safe. Mining operations were to be conducted in the No. 1 entry. This entry had taken a sudden dip and faulty seam and roof conditions were encountered about 14 feet outby the face. The previous shift had driven the left side of the place about 5 feet in advance of the right side in an effort to gain better control of the roof. Before starting mining operations, the crew serviced the mining equipment and changed cutter bits on the continuous-mining machine. After servicing the equipment, Robinson made an examination for gas in No. 1 entry and, finding it clear, trammed the mining machine to the face. Two roof bolts were installed on the right side of the working place. After the two roof bolts were installed, the continuous-mining machine was sumped near the bottom in the center of the place. (See sketch.) The coal face was sheared midway to the roof when Sabula observed gas burning at the face and signaled Robinson to stop the machine. Robinson immediately shut down the machine, left the water sprays operating, and used the water hose installed in the cab of the mining machine to extinguish the flame. The flame was extinguished in 30 seconds. Knapik and Robinson made tests for gas with permissible flame safety lamps but gas was not detected. Mining operations were discontinued until the investigating committee made their investigation. At the time of this investigation, the No. 1 entry had been advanced 65 feet from the open crosscut. Faulty seam conditions were evident in the face area. Approximately 19,400 cubic feet of air a minute was measured at the entrance to No. 1 entry, and 7,500 cubic feet of air a minute was measured at the inby end of the line brattice. Methane was being liberated freely from the coalbed and contiguous strata. Accumulations of methane were not detected with a permissible flame safety lamp or an electrical methane detector. The line brattice was about 13 feet from the face. The 18 properly directed water sprays mounted on the continuous-mining machine were functioning. Most of the cutting bits had been changed prior to mining operations and were in good condition at the time of the investigation. CONCLUSION The ignition was caused when gas emitting from feeders at the face was ignited by frictional sparks and/or heating created by the cutter bits of the continuous-mining machine striking pyritic intrusions imbedded in the coalbed in a faulty seam area. Contributing factors were maintaining an irregular coal face in a known faulty area. and failure to extend the line brattice as close as possible to the face. RECOMMENDATIONS 1. When mining or penetrating a faulty coal seam, a reasonable effort should be made to keep a square or flat face. 2. The ventilating current should be directed as near the face of the working place as possible by extending the line brattice to carry away gases being liberated at the coal face. ACKNOWLEDGMENT The cooperation of mine officials and employees, members and officials of the United Mine Workers of America, and the State mine inspector during this investigation is gratefully acknowledged. Respectfully submitted, /s/ E. M. Rudolph E. M. Rudolph Federal Coal Mine Inspector Approved by: /s/ T. J. McDonald T. J. McDonald Acting District Manager Coal Mine Safety District A |