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active workings was pronounced. The dislodged timbers, overturned cars, bent trolley hangers, the condition of the bodies of the victims, and other evidence indicated clearly that the explosion attained its maximum velocity in the active working section of the 13 and 14 east.

FLAME The area traversed by the flame of the explosion was determined by a careful examination of the active workings and the accessible parts of the abandoned workings within the explosion area. In this examination, evidence of flame was indicated by deposits of coked particles on mine surfaces and timbers, bits of burned paper and clothing, and charred or burnt splinters on timbers left standing in the explosion area. The flame extended throughout the entire explosion area and outby 5 and 6 south. Signs of intense heat and flame were observed particularly in the rooms off 13 parallel entry inby the 8 north entry. Particles of coke, burnt paper, and charred timbers were observed in the accessible area explored along the 13 and 14 east inby the active working places adjacent to the 7 and 8 north and south entries. Numerous streamers of soot were observed hanging from the roof, and heavy deposits of coke and ash were noted on the floor about 200 feet inby the 9 and 10 south entries. The bodies and clothing of all victims of the blast were burned, which proved definitely that the flame extended throughout the entire explosion area.

FACTORS THAT PREVENTED THE SPREAD OF THE EXPLOSION The explosion was localized and was confined to a small area within the 13 and 14 east section. The 13 and 14 east section was ventilated by a separate air split and the other working sections into which the explosion failed to propagate were not affected by the afterdamp. The main haulage road and active workings were well rock-dusted, the last application of rock dust in the 13 and 14 east section having been made on the night previous to the explosion. The back entries had been rock-dusted by machine during development work, and rock dust was suspended in bags at intervals along the entries. The back entries have numerous falls and the floor was generally covered with incombustible rock, but the abandoned part of the 13 and 14 east inby the 7 and 8 south was coated' with considerable fine coal dust. That the explosion failed to propagate and was confined to a small area because of the recent liberal applications of rock dust to the mine surfaces throughout the active workings, was demonstrated emphatically. The efficacy of the generalized method of rock dusting over any substitute measure as a means of preventing an explosion from propagating throughout the mine was proved conclusively. Another factor in retarding the development of high velocities as the explosion traveled outby was the existence of large areas of open, abandoned workings which provided space for the relief of pressure.

TABLE 2.-Air analyses report
(Mine: No. 8. Company: Old Ben Coal Corp. Collected: July 25, 1947)

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SUMMARY OF EVIDENCE Because of the squeezed and caved condition of the 13 and 14 east entries inby the present active workings, it was only possible to get about 200 feet inby the 9 and 10 north and south panels with reasonable safety. Here the entries were

squeezed down to about 442 feet in height, and it is believed that a relatively short distance beyond which it was possible to travel these entries that they were caved tight.

For a distance of 200 feet inby the 9 and 10 panels it was observed that there were streamers of soot from the roof and deposits of coke on the floor, indicating slow burning of the gas and dust with little or no violence.

Inby the 9 and 10 panels props that had been broken by the squeeze and which, therefore, would be easily dislodged had not been disturbed.

The absence of violence and the slow burning evidenced by the soot streamers on the roof is a phenomenon often observed in mines following explosions in tight ends where a balanced pressure builds up, such as in a room or entries inby the last crosscut, and substantiates the belief that the 13 and 14 entries were closed tight at some point beyond the 9 and 10 panels.

Outby the 9 and 10 panels heavy deposits of coke were observed, indicating that coal dust entered into the explosion to a large extent, beginning at a point perhaps 100 feet outby the 9 and 10 entries. A build-up of pressure and violence toward the active workings was very apparent. Props and other material had been moved outby. This build-up of pressure and violence unquestionably was due to the ignition of fine coal dust.

As soon as the flame reached the active workings which had recently been thor. oughly rock-dusted, a rapid diminution of both flame and violence took place. The further rapid diminution of pressure and violence outby along the 13 and 14 east entries was doubtless due to the release of pressure by expansion into the panel entries that were still open, namely, 7 and 8 north and south, and 5 and 6 north and south.

In view of the above observations it is believed by the investigators that the explosion originated in and was confined almost entirely to the area in which this investigation was conducted.

POSSIBLE CAUSES OF THE EXPLOSION When the cross entries have been developed to their limit and the rooms off the panel entries have been completed, rooms are driven into the barrier pillars along the cross entries, starting at the inby end and working out, before the territory is abandoned and sealed. During the period of time that is taken to complete this work the worked-out areas squeeze and cave to the extent that these areas cannot be ventilated or inspected properly, although gas may accumulate extensively in the abandoned areas.

There was no doubt that the explosion was caused by an ignition of gas, but the actual source of ignition was not determined positively, although two such sources must be given serious consideration if we are to be sincere in the determination to prevent a recurrence of a disaster of this kind. First, the gathering locomotive was found on the inby end of the return-air side of the split and about 300 feet from the worked-out territory. The nip of the locomotive trailing cable was still connected to the trolley wire and could be construed as evidence that the locomotive was in operation. Reports to the effect that the controller on this locomotive was in the off position could be reasonably discounted, as the natural reaction of the operator when the explosion occurred would be to close the controller. The loading machine had broken down and was partly dismantled, the trailing cable was not connected to the power wire, and the men were loading the coal by hand. The mining machine was parked, and it was stated that no drilling was being done in the places.

Although the evidence points to the fact that the gas was ignited by the locomotive operating at 8 north, the possibility that it was ignited by someone smoking cannot be entirely dismissed. One of the recovery crews about to enter the mine was cautioned against carrying any matches or cigarettes into the mine, and the men deposited numerous packages of cigarettes and matches that they had been carrying in their working clothes at the collar of the shaft, which indicates that the men had been in the habit of carrying smokers' articles into the mine. Even in those mines in Illinois where smoking has been prohibited, it has not been a practice to search the men for smokers' articles before they enter the mine.

The abandoned area inby and immediately adjacent to the last working places off the entries could have contained heavy accumulations of methane that could easily be forced out into the active workings by a fall of roof in any part of the vast expanse of abandoned workings, by a slight change in barometric pressure, or by restoring the ventilation after it had been disrupted by keeping one of the doors open for an excessive length of time.

It was quite obvious to the men engaged in the recovery operations that the abandoned area adjacent to the active workings was squeezing and caving at that time and undoubtedly had been during the day, and it is an undisputed fact that the liberation of methane becomes more active when caving and squeezing occur.

Therefore, it was concluded by the Bureau men engaged in the recovery work and investigation that some accumulated gas had been forced into the active working area, or that gas had accumulated in the working section due to an extended disruption of the ventilating current, where it was ignited by a spark or arc from the gathering locomotive, or possibly by one of the workmen smoking.

The State mining board issued a preliminary statement to the effect that an accumulation of gas in the abandoned area was ignited in some unknown manner to cause the explosion. However, the Bureau investigation and subsequent statements of the survivors would seem to indicate that this preliminary statement will be revised in the final report.

Following are the statements of the three men who survived the explosion in the 13 and 14 east entries of the Old Ben Coal Corp. No. 8 mine, July 24, 1947, obtained July 30, 1947.

Statement of Frank Casper, West Frankfort, Ill., motorman for servicing the loading machine:

"As the loading machine was broken down, I decided to walk out of the room to see what was going on in the rest of the section. When I reached the entry switch, I saw the gathering locomotive up at the 8 south entry changing cars for the hand loaders. As I was looking up the entry, I saw a ball of fire start at the locomotive and the fire came down the 13 east entry from the 8 south. I fell to the ground and there was a loud report like a shot, and when the fire reached me it was making a swishing sound. I was picked up by the force and thrown down the entry. The lens and globe in my electric cap lamp were destroyed so I was in the dark. I found one rail and followed it down the entry until I came to a crosscut on the left side. I crawled through the crosscut and came to fresh air and decided to stay there. The first men to reach me were James Rainey, the motor boss, and Don Bowker, the mine manager, and when they arrived I walked out to the mouth of the entry with assistance.

"I did not hear the drill or machine running, but I did hear the locomotive running up at the 8 south switch.

"We had gas up around the 9 and 10 north entries when we were working in the pillars there.”

Statement of Charles Smith, West Frankfort, Ill., gathering locomotive operator :

"I had exchanged locomotives with Curtis Stagner, the relay motorman, and in company with Thomas Kirby, the main-line motorman, I was sitting on Stagner's locomtive. After some switching, Stagner had just changed the three hand loaders in the rooms off the 13 east parallel entry. As I was watching him come out on the 13 east entry, I saw a ball of fire and a second later I heard a swishing sound, and Kirby and I were thrown off the locomotive and landed out by it. We were in the dark, as the headpieces of our electric cap lamps were destroyed. I told Kirby that we had better get into the intake air course and started to crawl along the rail. I found a stopping, but there was no opening in it. I called to Kirby and he said that he could not make it any further, so I told him to stay there and I would see if I could find a crosscut with an opening in it. I started to crawl up the entry, but lost consciousness and do not remember anything more until I woke up in the hospital.

"The machine and drills were not being operated at the time of the explosion.

"My belief is that the locomotive that Stagner was running ignited the gas at 8 south off 13 east entry.”

Statement of Thomas Kirby, West Frankfort, Ill., main-line locomotive operator:

"Charles Smith and I were sitting on Stagner's locomotive at 6 north off 13 east entry. We saw Stagner switching around with his locomotive at 8 south off 13 east and saw a ball of fire. We only had time to turn our heads when we heard a swishing sound and we were thrown off the locomotive. We talked about getting into the intake-air course, and then I lost consciousness.

“I really believe that the locomotive that Stagner was operating at the 8 south off 13 east ignited the gas."

LESSONS TO BE LEARNED FROM THE CONDITIONS AS THEY RELATE TO THE EXPLOSION

1. The outstanding lesson to be learned from this disaster is that the practice of working places adjacent to open, abandoned sections where gas may accumulate is extremely dangerous. Abandoned workings should be ventilated properly and inspected frequently, or they should be sealed.

2. Where single doors are used to control ventilation, all precautions should be taken to see that the doors are not kept open for an extended period of time.

3. It is of paramount importance that the officials in a gassy mine keep their flame safety lamps with them at all times and make frequent examinations for gas in tbe working places.

4. The practice of smoking in gassy mines, surreptitiously or otherwise, must be discontinued, if mine disasters are to be avoided.

5. Searching employees for smokers' articles before they enter the mine should be considered by the men to be an essential safeguard, rather than a violation of personal rights, and it should be done at all mines where smoking underground is prohibited.

6. Bags of rock dust suspended from timbers were proved to be ineffective insofar as preventing propagation of the explosion, as most of the bags did not trip and the rock dust was not dispersed into the atmosphere.

RECOMMENDATIONS Recommendations concerning the safe operation of this mine were made in reports of previous Federal inspections, the last inspection having been made January 7–10, 1947. Recommendations in this report, therefore, are limited to conditions as they related to explosion hazards. RECOMMENDATIONS BASED ON THE FEDERAL MINE SAFETY CODE FOR BITUMINOUS

COAL AND LIGNITE MINES OF THE UNITED STATES

ARTICLE V. VENTILATION AND MINE GASES

Section 96.--Abandoned workings should be sealed or ventilated.

Section 100.—Mine officials whose regular duties require them to inspect working places should have in their possession, when underground a permissible flame safety lamp in safe working condition.

ARTICLE VI. COAL AND ROCK DUST Section 16.—Where mining operations raise an excessive amount of dust into the air, water or water with a wetting agent added to it or other effective methods should be used to allay such dust at its source.

ARTICLE VIII. ELECTRICITY Section 9d.-Where nonpermissible electric equipment is being used, care should be taken to protect the workmen by making frequent examinations of the air for methane content and by preventing interruptions of the ventilating current.

Section 99.-In all face workings where electrically driven equipment is operated, frequent inspections for methane should be made. If a dangerous condition exists, the machines should be stopped until such dnagerous condition is removed.

ARTICLE XI. MISCELLANEOUS Section 6a.-Because of explosion and fire hazards, matches or other flamemaking devices should not be carried into the mine. SUPPLEMENTAL RECOMMENDATIONS NOT SPECIFICALLY COVERED BY THE FEDERAL

MINE SAFETY CODE 1. In any section of a mine liberating an excessive amount of methane, or in a section being worked adjacent to an abandoned area that might contain accumula. tions of methane, the doors controlling the ventilation should be built in pairs to form air locks or single doors should be attended.

2. Air that has passed by abandoned areas that cannot be inspected should not be used to ventilate active workings.

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