Three men erected a barricade near the face of 2 south and died behind
it. The other 7 men erected a barricade in 3U drift; 2 of these men left the barricade and traveled to the shaft station where they were met by a rescue crew and brought to the surface at 11:55 a.m., August 28, about 19 hours after the explosion occurred.
The other 5 men remained behind the barricade until a recovery crew contacted them and they reached the surface without assistance at 6:30 p.m., August 29, about 50 hours after the explosion. A surface employee received minor injuries and was hospitalized.
Bureau of Mines investigators believe the explosion originated in the shop area where an explosive mixture of combustible gases was ignited by electrical arcs or sparks, open flame, or heated metal surfaces. Forces of the explosion extended to the shaft station,
up the shaft to the surface, and throughout the greater part of 2 south and 3U drifts.
The Cane Creek mine, Potash Division of the Texas Gulf Sulphur Company is in Grand County about 20 miles southwest of Moab, Utah, by road, and is reached by paved State Highway 279. The mine is served by the Denver and Rio Grande Western Railroad, and is being developed on State and Federal land.
The mine is in the development stage and production of ore has not been started. A contract for the sinking of the shaft and driving the development drifts in waste to the ore body was given to the Harrison International, Incorporated, of Miami, Florida, and
practically all work being done at the time of the explosion was by the contractor. Likewise, most underground employees were the contractor's.
The work schedule was 7 days a week, 3 shifts a day. The average underground employment for Harrison International, Incorporated was 80 men, divided approximately
into 30 men on day shift and 25 men each on swing and graveyard shifts. Engineering and maintenance of some equipment was provided by Texas Gulf Sulphur Company. There were many occasions for personnel of the Texas Gulf Sulphur Company to enter the mine, such as for ventilation checks, temperature readings, gas testing, and for collecting other pertinent data. Texas Gulf men worked underground in the shop regularly on 2 shifts daily.
A regular Federal inspection of this mine was made November 28-29, 1961, when the shaft was at a depth of 840 feet. In addition, four separate investigations of fatal accidents were made by Bureau of Mines personnel prior to the explosion.
Examination of the entire mine after the disaster showed that the explosion originated in the shop area. All evidence indicated that the combustible gas ignited in the shop area was released at the face of 2 south drift when the round of shots were fired therein
at 4:20 p.m.
As mentioned previously, the velocity of the air moving from 2 south drift to the shaft would move the combustible gas from the face of 2 south to the shop area at a suitable rate of flow to initiate the explosion in the shop area at 4:40 p.m. Ignition of the
combustible gas in the shop area might have and easily could have been from an electric arc or spark, an open flame, or a heated exhaust manifold on a shuttle
Some of the more likely ignition sources were:
Arcs or sparks from the battery-charging clamps being placed on or removed from the battery terminals on the No. 5 shuttle car, the switch on the power panel and the shop being opened or closed, the power cable to the battery charger being placed in the power outlet, or an electric circuit on a shuttle car or from equipment or circuits in the shop area.
An open flame such as from a match or cigarette lighter or from a cutting torch.
Heated surfaces such as the filaments in electric light bulbs or an exhaust manifold on a shuttle car. The possibility that the combustible gas that was ignited could have come from a source other than liberation from the strata after blasting in 2 south drift was recognized. All such sources were investigated thoroughly, including the possibility that acetylene was the combustible gas, but there was no evidence found to support such possibilities, and analyses of dusts and residues after the explosion indicated that the combustible gas ignited had not been acetylene.
Damage was confined generally to the shaft, shaft structures on the surface, and the immediate areas of the shaft station and shop areas. Elsewhere, underground damage was slight.
Factors Preventing Spread of Explosion
This disaster was strictly a gas explosion, and all available fuel (mixture of combustible gas and air) was ignited. Mine dusts are not explosive and other materials, such as oils and explosives, that might have propagated the explosion were not ignited.
Summary of Evidence
Conditions observed in the mine during recovery operations and the investigation that followed, together with information made available during interrogation and discussions with officials and employees of the Texas Gulf Sulphur Company and Harrison International, Incorporated provided evidence as to cause and origin of explosion.
The evidence from which the conclusions of the Bureau of Mines investigators are drawn are summarized as follows:
One explosion occurred in which only combustible gas was involved.
The explosion occurred at 4:40 p.m., August 27, 1963. This time was given by an underground official of the Texas Gulf Sulphur Company, who survived the explosion and was corroborated by an employee of Harrison International, Incorporated, who was on the surface at the time.
All victims in the vicinity of the shop and shaft station and two victims in 2 south drift were killed instantly. Three men in the 2 south face area and three others in 3U drift died later of asphyxiation.
The 2 south face was blasted 20 minutes prior to the explosion.
Combustible gas was liberated from the 2 south face. Sample No. 1289, collected August 31, 1963 in the face of 2 south after the explosion, contained 6.7 percent total hydrocarbons composed of 4.74 percent methane, 1.1 percent ethane, 0.5 percent propane, 0.24 percent butanes, and 0.12 percent pentanes.
Gas had been emitted with sufficient pressure during blast hole drilling in shale to eject the drill with force and push the drill and operator back 20 feet from the face. Also, gas was released occasionally from fractures encountered in the strata during mining operations.
The calculated velocity of return air current in 2 south was adequate to carry combustible gas released at 2 south face after blasting at 4:20 p.m. to the shop at the time of explosion.
A fan, operated openly in the shop area, was capable of drawing some of the return air from 2 south and recirculating it within the shop.
Failure to find soot or low density carbon particles during comprehensive tests made of samples of fine solid materials collected in the shop indicates that acetylene did not enter into the explosion.
There was no electrical face equipment in use at the time of the explosion. Rock bolting with compressed-air stoppers was in progress in the face of 3U drift, and the mobile loader was parked about 125 feet from the face in 2 south; no blasted rock had been loaded out.
Power circuits and the 110-volt lighting system in the shop were energized.
A permissible flame safety lamp was left hanging (between shifts) in the shop area. Laboratory examination of this lamp indicates that the lamp was not lighted at the time of the explosion.
Some persons using the permissible flame safety lamps had not been trained adequately in their use as gas-testing instruments.
Some smoking continued in the mine regardless of the "No Smoking" rule instituted following the July 31, 1963, gas ignition. A search program to dissuade persons from carrying smoker's articles underground had not been instituted.
Not all the permissible electric face equipment was maintained in permissible condition.
Diesel shuttle cars approved for use in nongassy noncoal mines were used in the mine.
Cause of Explosion
The disaster was caused by the ignition of combustible gas in the shop area by electric arcs or sparks, open flame, or heated metal surfaces. The gas was liberated from blasting in the face of 2 south drift, and was carried by return air toward the shop. The fan, operated openly in the shop area, drew some of the gas-laden return air from 2 south into the shop and then recirculated it.
Historical Summary of Mine Disasters in the United States - Volume III