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It will be observed from this table that 4 of the 12 samples collected contained less than the 65-percent incombustible matter recommended as a minimum by the Bureau of Mines; however, this deficiency was not a factor in this explosion.
Additional dust samples were collected during the investigation of the explosion, the analytical results of which are shown in table 1.
It will be observed that the roof and rib samples contained from 31.7 to 78.4 percent incombustible matter and the incombustible contents of the road sam. ples were from 25.4 to 46 percent. Attention is called to the fact that all samples were collected within the explosion area and the ribs, roof, and floor were coated heavily with coal dust carried and deposited by the explosion. Samples P-561 and R-4 were collected at the point where the forces of the explosion died out and the ribs at this location showed only a light film of coal dust.
TABLE 1.—Dust analyses report
Main haulage was accomplished with 13-ton electric trolley-pole locomotives over a single-track system except for a distance of 4,000 feet from the shaft bottom where a double-track system was used. Trolley-pole and cable-reel locomotives were used for servicing loading machines and secondary haulage.
The cars of coal were hoisted on two self-dumping cages to the top of the tipple where they were dumped. The coal hoist, which was also used for handling men and materials, was of the double step-up drum type and was electrically driven. One and one-half-inch-diameter ropes were used. The hoist was equipped with automatic overwind, overspeed, and stop controls, and a positiveacting indicator to show the position of the cages. The hoisting equipment, including the rope, was inspected three times daily by the top cager and engineer, and written records were kept of these inspections.
ELECTRIC EQUIPMENT UNDERGROUND Electric power was purchased from the Central Illinois Public Service Co. and was received at the transformers as 33,000 volts alternating current and was stepped down to 2,300, 220, and 110 volts alternating current by transformers located on the surface. A total of five substations was provided and these stations were also located on the surface.
Electric power was taken into the mine through the air shaft, the upcast shaft near the bottom, and a borehole located near 13 east main south. The power was distributed in the mine through insulated cables as 275 volts direct current. This was the only electric power in the mine, and it was used to operate all inside machinery. The feeder and trolley lines throughout the mine were securely
supported on insulated hangers and were sectionalized at about 3,000-foot intervals. Cut-out switches were also provided for the trolley lines at all intersections. All power and trolley lines were in return air.
All mining machines, loading machines, drills, and cable-reel locomotives were of the nonpermissible type and received their power through trailing cables connected to power wires located in return air.
Incandescent electric lights operated from the mine circuit were installed at the shaft bottom, track switches, doors, and other strategic places. Permissibletype electric cap lamps were used by all underground employees for individual illumination. All underground foremen used permissible flame safety lamps which they cleaned, filled, assembled, and left at the mine examiners' office when not in use.
Rules prohibiting smoking have been adopted.
EXPLOSIVES AND BLASTING
Generally, Cardox model 3–200 was used to blast coal and the shells were charged at the Cardox Corp. charging plant located at Benton, Ill., about 9 miles from the mine. However, Airdox was used to break coal in one section of the inine. The charged Cardox shells were hauled to the mine during the morning and loaded into specially constructed insulated cars. The cars were sent underground during the off shift, and the charged shells were stored in insulated cars in the working sections.
Three drillers worked together and started to work at 10 a. m., which is 2 hours after the regular shift starts. Two nonpermissible post-mounted drills were used in each place and two holes were drilled concurrently. While two men operated the drills, the third man removed a predetermined number of charged shells from the storage car and leaned them against the rib near the working face and wired them. The negative wire was attached first and the wires were short-circuited before the positive wire was attached. Both bare and insulated wires were used in wiring the shells.
On completion of the drilling, the charged shells were inserted into the drill holes. Twin-conductor, rubber-covered cables were used and were at least 125 feet long. Short-circuits from the charged shells were removed just prior to attaching the blasting cable to a Cardox shell. Nonpermissible Atlas 2A, 10-shot blasting machines were used for all blasting, and the shots were fired after all men except the shot firers had left the mine.
MINE RESCUE About 50 men at this mine have received mine rescue training at various times, but none has had mine rescue training in recent years.
Six gas masks were available at the mine, and six self-rescuers were kept in a dustproof metal box at 11 east off main south in intake air. The nearest State. maintained mine rescue station and mine rescue team was at Benton, Ill., about 9 miles from the mine. Other State-maintained and privately owned mine rescue stations and mine rescue teams were from 35 to 120 miles away. The United States Bureau of Mines rescue truck and apparatus were located at Vincennes, Ind., about 118 miles from the mine.
All buildings within 100 feet of the mine openings, and vital structures were of fireproof construction. The electrical circuits were installed on knobs, and enclosed switches were used. The surface fire protection consists of pipe lines, water hose, hydrants located at strategic places, and an elevated steel water 'tank. The tank, which has a capacity of 10,000 gallons of water, is supported on structural steel members. Water is supplied by the city of West Frankfort Water Co. Additional fire protection is provided by portable fire extinguishers of various types, located at convenient places in the surface buildings.
The fire-fighting equipment underground consisted of soda-acid fire extinguishers, volatile liquid fire extinguishers, one portable water tank with a capacity of 500 gallons, one portable pump, bags of rock dust throughout the mine, 2-inch water line extending from the surface through the hoisting shaft along the main haulageways to 5 and 6 south on 15 west, and water hose located at strategic places along the haulageways. Water taps were placed at 300-foot intervals.
PREVIOUS EXPLOSIONS IN THIS MINE A gas explosion occurred in this mine on January 14, 1921. Forty-one men were in the mine at the time of the explosion, but only 21 were working in the section of the mine affected. One man died 24 hours after the explosion ; 9 men were seriously burned, and 11 were slightly burned. The explosion was caused by a workman smoking. Rock dust prevented the explosion from spreading to other parts of the mine. These accident data were obtained from a report of the United States Bureau of Mines by J. J. Bourquin.
A second explosion occurred on December 1, 1929. Twenty-four men were in the mine at the time of the explosion, but only seven men were working in the section affected. All seven men were killed instantly. Rock dust prevented the explosion from spreading to other parts of the mine. These accident data were obtained from the Monthly Safety Report of the Old Ben Coal Corp., written by John E. Jones.
MINE CONDITIONS IMMEDIATELY PRIOR TO DISASTER The mine was operating normally, and no unusual conditions, insofar as could be ascertained, had been reported prior to the time of the explosion. The fan was working properly and no interruptions had occurred in the main ventilating system.
The mine examiners' reports for July 24 indicated normal mining conditions, and all places in the 13 and 14 east section were reported to be in safe working condition. The ventilating current was traveling in its regular course and the mine examiner reported that 6,600 cubic feet of air a minute was passing through the last open crosscut. The 13 and 14 east entries had been driven as far in as the 21 and 22 north and south room-panel entries, but, at the time the explosion occurred, the barrier pillars along the 13 and 14 east entries had been partly recovered to a point midway between the 8 and 9 north and south room-panel entries by driving short rooms into these pillars. The worked-out area was not ventilated properly or sealed.
The United States Weather Bureau offices at Springfield, Ill., and Cairo, Ill., showed barometric pressures of 29.81 and 29.90 inches of mercury, respectively, at noon on the day of the explosion. A barometer at the mine showed the pressure to be 29.70 inches of mercury in the morning. The pressure was constant at both Weather Bureau stations, with a slight normal midday drop of approsimately five or six one-hundredths of an inch,
The explosion caused no damage on the surface. The only place affected in the mine was the 13 and 14 east section of the main south where the explosion occurred.
The force of the explosion demolished two and damaged one of the concreteblock stoppings between the 13 and 14 east; three ventilating doors that were erected in crosscuts between 13 and 14 east were destroyed ; several (ross bars and timbers were blown out, permitting small roof falls; trolley and feeder lines were torn down in several places in the section; and debris, loose rock, and dust were strewn over the track and roadbed. Because of a suspected fire, the management decided to recover the equipment and seal the section, and did not anticipate working this section again; this work was started as soon as the equipment was recovered and the section was closed the following day with temporary seals near the entrance of the 13 and 14 east off main south.
STORY OF EXPLOSION AND RECOVERY OPERATIONS The explosion occurred at about 12:35 p. m., July 24, 1947, in a working section about 12,230 feet from the main shaft and about 6,000 feet from the nearest escape shaft. The trapper at the 11 east on the main south noticed smoke and dust coming out of the main south entry. He ran to the 13 east and cut off the power from that section. He then went to the telephone and called the mine manager, who was at the main shaft bottom, and told him that something was wrong in the 13 east and that it appeared to be a mine fire. The mine manager notified the surface officials and then proceeded to the 13 and 14 east section.
Mr. Roy Adams, general superintendent, immediately called the Illinois State Department of Mines and Minerals and the superintendents of the Benton and Herrin mine rescue stations, who were asked to send their rescue teams to the Old Ben No. 8 mine at West Frankfort as soon as possible.
The district office of the Federal Bureau of Mines at Vincennes, Ind., was first notified by Mr. H. C. Brumbaugh, Federal coal-mine inspector, who arrived at the Old Ben No. 8 mine at 1:45 p. m. to see Mr. Roy Adams on business. Upon his arrival at the mine, he was informed by Mr. Adams that there was a fire in the 13 east section off main south and that a number of men might be trapped. Mr. Brumbaugh immediately notified Mr. C. A. Herbert, supervising engineer, district E, by telephone at about 2 p. m. Mr. Herbert then directed several other Bureau men to go to the mine. The names of the Bureau personnel who rendered assistance during the rescue and recovery work are as follows: W. A. Gallagher, W. R. Chick, H. C. Brumbaugh, T. C. Higgins, James A. McCune, G. W. Colbert, and Roy Capps. Seven members of the State mine inspection department were present and participated in the rescue and recovery operations. The names and titles of these men are as follows: Harold M. Walker, director; Robert Weir, assistant director; Elmer Edmonds, inspector-at-large; James Sneddon, safety engineer; and J. R. Wilson, Roy McCluskey, and John Golden, mine inspectors. Two State mine rescue station superintendents and rescue teams were also present and participated in the work.
Mr. Howard Lewis, underground superintendent, and John E. Jones, safety engineer, for the Old Ben Coal Corp. were notified immediately of the trouble at the mine. Upon Mr. Lewis' arrival, he immediately entered the mine and proceeded to the 13 east where he contacted the mine manager, who informed him that it was an explosion that had occurred instead of a mine fire. Mr. Lewis, Mr. Bowker, mine manager, and several other men entered the 13 east. When they reached the affected area, they found four men in a burned and dazed condition and one man dead from the effects of the explosion. These men were removed to the surface promptly. Upon the arrival of Mr. J. E. Jones and State Mine Inspector Elmer Edmonds, which was about 2:15 p. m., these two men, H. C. Brumbaugh, Federal coal-mine inspector, and Ernest Green, assistant general superintendent, immediately entered the mine. About halfway between the main shaft bottom and 13 east they passed the trip in which the four injured and one dead man were being conveyed to the shaft bottom. Upon their arrival at the 13 east which, they were met by the mine manager, Mr. Howard Lewis, superintendent, and several other mine employees. They entered 13 east entry which is the return air course of the 13 and 14 east section and proceeded to a crosscut outby 5 south where the door had been blown out. At this point they entered the 14 east entry which was the intake air course for this section and proceeded to restore the ventilation and begin the recovery work. Canvas brattices were erected in the crosscuts where the concrete-block stoppings and wooden doors had been demolished by the force of the explosion. Work was continued inward on the intake air course entry. Six bodies were found in a crosscut about 60 feet above the 8 south room-panel entry off 13 east on the intake side of this section. The body of the face boss was found in the last place on the return air side in the place where the loading machine was broken down, and his safety lamp was found in the vicinity of old 7 north approximately 300 feet from his body, as shown on map, appendix B. Mr. W. R. Chick, Federal coal-mine inspector, arrived at the mine about 3:30 p. m. He immediately entered and joined the rescue party at the 8 south off 14 east main south. Other Federal coal-mine inspectors, State officials, and mine rescue teams arrived later and assisted in the recovery work which was completed at 12:30 a. m., July 25, 1947. The last body was found at 11:30 p. m., July 24, 1947. After the last body had been removed, four Federal coal-mine inspectors, who had been assisting in the recovery work, remained in the mine and immediately started an investigation to secure data pertinent to the explosion. After all the bodies were recovered, the company officials, State officials, and the Federal inspectors discussed the removal of the equipment because of the squeezing and falling of rock in the affected area. It was decided to remove the equipment, and this work was completed by 6 a. m., July 25, 1947.
On the morning of July 25, 1947, H. C. Brumbaugh and W. R. Chick, Federal inspectors, entered the mine and proceeded to make a sketch of the affected area. After the sketch was made, they decided to explore as much of the workedout area as possible above the working section and were accompanied by several of the company officials of the Old Ben Coal Corp. Two dust samples were collected inby the last working place on 13 east parallel entry and a coke sample from a prop about 150 feet inby 10 south on 14 east parallel entry. At 9 and 10 south and for a distance of 200 feet inby, soot streamers were observed banging from the roof, and deposits of coke and ash were observed on the floor. Further exploration of this area was considered to be too hazardous due to bad roof, smoke, and fumes.
DETAIL OF EVIDENCE The map of the 13 and 14 east section of the mine, appendix A, shows the underground abandoned and active workings and the course of the ventilating current previous to the explosion. The sketch of the explosion area, appendix B, shows on a larger scale the ventilating current previous to the explosion, and probable points of origin, the approximate area traversed by flame, and the approximate area affected by violence. In addition, this sketch shows the locations of bodies of the victims of the disaster, the direction of major forces, and the locations where dust and air samples were collected within the explosion area during the investigation.
METHANE AS A FACTOR IN THE EXPLOSION
The mine is recognized as gassy by the Illinois Department of Mines and Minerals and is classified as gassy by the Bureau of Mines. Considerable methane was liberated in the mine during normal operations. At the time of the last regular Federal inspection, the mine was liberating in excess of 616,000 cubic feet of methane in 24 hours. All of the samples collected during that inspection showed some methane, the contents ranging from 0.19 to 1.13 percent. Table 2 contains the analytical results of air samples collected during the investigation. It will be observed that the methane content of the face samples was 0.33 and 0.36 percent, respectively, and the samples collected in return air showed methane ranging from 0.11 to 0.35 percent, although when these samples were collected the volume of air passing through the section was 27,000 cubic feet a minute, compared to a normal quantity of 6,600 cubic feet a minute. While no accumulations of gas were detected during the investigation, although tests were made frequently with a permissible flame safety lamp, the results of the analyses of the air samples indicate that the mine was liberating considerable methane at the time of the explosion, and any interruption of the ventilating current might permit an accumulation of explosive gas in the active workings. This is particularly true under the conditions prevailing in the 13 and 14 east section at the time of the explosion where the active workings were adjacent to vast areas of abandoned workings. These abandoned workings were not sealed, they were not ventilated, the conditions in the abandoned workings did not allow thorough inspections because of squeezing and falls of rock, and they might have contained dangerous accumulations of methane.
Only a small area in the 13 and 14 east section was affected by the flame and violence of the explosion. The afterdamp resulting from the combustion of gas and dust passed directly into the main return and none of the other working sections was affected. The forces were extremely violent in some portions of the explosion area, but diminished rapidly due to expansion into abandoned workings. The direction of forces was determined wherever possible by the movement of material, such as the dislodgment of timbers, shattered remains of stoppings and doors, derailment and overturning of cars, scattered debris, and the bending of trolley hangers. The forces were generally outby from the abandoned area explored inby the 9 and 10 south throughout the explosion area. The velocity of the explosion was extremely rapid in the area between the 5 and 6 north and south and 7 and 8 north and south entries, especia in the vicinity of the 7 and 8 north and south entries. The velocity of the explosion diminished rapidly in the vicinity of the 5 and 6 north and south entries and died out completely at 3 and 4 north and south entries. There was considerable evidence of forces traveling into the abandoned 5 and 6 south entries which obviously afforded pressure relief for the explosion.
While there was much evidence of heat and flame in the abandoned area for a distance of 200 feet inby the 9 and 10 south entries, there was slight evidence of force in this area. Indication of forces traveling outby was plainly evident by the position of dislodged timbers and debris. Definite evidence that the forces were traveling outby and increasing in violence as they approached the