the self-closing type with a latch or other means to prevent opening (if kept normally closed) by reversal of the air current.

8. Direction signs in as many languages as needed to be understood by the mine personnel should be posted at suitable points, indicating plainly the direction of escapeways. 9. Timbered shafts should have ample facility for quick-action fire protection; and waterlines for fire protection should be extended through mine workings, especially if much timber or other combustible matter is present.

10. Means should be provided for warning men promptly in an emergency.

11. Rescue apparatus is likely to be of great value in saving life and property if a serious mine fire occurs, such as that in the Granite Mountain shaft or the Argonaut shaft (described below). Men should be carefully trained to use such apparatus and to know its advantages and limitations.

Argonaut Mine Fire, Jackson, Calif.

A fire in the main shaft of the Argonaut mine in August 1922 killed 47 miners. This mine is a gold quartz property and at the time of the disaster employed about 165 men underground. It was worked through an inclined (57°) shaft that followed the dip of the vein 4,900 feet. The shaft had 3 compartments, each 4 by 5 feet, and was heavily timbered. Two compartments were used for skip hoisting; the manway contained a ladderway, a compressed-air line, a pump column, a high-tension cable, electric-light wires, and signal and telephone lines. Levels were driven at approximately 150-foot intervals. Ventilation was supplied through a second shaft 800 feet deep and offset raises connecting to the lower levels of the mine. This ventilation-raise system was equipped with ladderways from the bottom level to the surface. At the collar of the ventilation shaft was a nonreversible fan exhausting about 40,000 cubic feet of air per minute from the mine. Wooden doors directed the air in the downcast Argonaut main shaft to the lower levels.

About 11 p. m. the shift boss and 2 skip tenders smelled smoke at the 4,200foot level of the main downcast shaft and realized that there was a fire in the shaft above them. They had themselves hoisted to the 3,000-foot station and found 2 timber sets burning on the hanging-wall side just below the station. One of these men remained at the 3,000 station to observe conditions; the other two went in the skip through the fire to the 2,000-foot level, where they telephoned to the hoisting engineer, and then went to the surface to obtain means of fighting the fire. Soon after their arrival the mine telephone, signal system, and lights went out of order. The 47 men below were cut off. Smoke began issuing from the ventilation shaft and soon was backing up the main shaft. Men equipped with oxygen breathing apparatus entered the skip and futilely attempted to combat the fire. Changes in the fan housing to allow reversal of the air current would have taken several hours and probably would have been useless, as doors in levels above the fire zone normally closed would have been pushed open by a reversal of the air current and short-circuited the air; the air current was not reversed during the fire fighting. Exploration or rescue work through the ventilation raises was impracticable because 4 to 5 hours would be required for the men to climb back out of these raises, all in highly toxic air from the fire. Men wearing oxygen breathing apparatus controlled extension of the fire up the shaft by means of a high-pressure waterline and hose and then put in an airtight bulkhead about 2,300 feet down the main shaft. Access to the lower levels of the Argonaut mine could be gained by reopening caved connections with the adjoining Kennedy mine and driving some 80 feet in solid rock; 21 days of the most arduous labor opened a way to the 4,200-foot level of the Argonaut mine. Another connection from the 3,900foot level of the Kennedy mine through 140 feet of solid rock was being driven at the same time as that on the 3,600-foot level but was not completed. Fortysix bodies were found on the 4,350-foot level behind a double bulkhead built of waste, boards, and clothing. Evidently gases had penetrated the bulkhead, and the men had died within a few hours after the fire. The 47th body was found later on one of the levels below the 4,350.

Three possible causes for this fire have been advanced: (1) Electricity; (2) incendiarism; and (3) lighted cigarette or match inadvertently thrown to the hanging-wall sets. Most of the investigators believed that a short circuit in the 2,300-volt powerline in the shaft caused the fire. The skip tender testi

8 Pickard, B. O., Lessons From the Fire in the Argonaut Mine: Bureau of Mines Tech. Paper 363, 1926, 39 pp.

fied that during his observation the fire was spreading from about the location of the shaft wiring. The point of origin was near a cast-iron junction box, where the armor and outer insulation had been removed from the cable to allow it to enter the ends of the box. On the day before the fire some decayed timber just below the 3,000-station chute had been replaced. The old timber, stored temporarily in the manway, may have been thrown against the power cable, jarring or displacing the wiring at the junction box. A short circuit in the junction box or in the cable itself could have ignited trash in the chute or the stored punky timber. After the fire there was evidence of arcing about the cable at the junction box. The power cable comprised 3 smaller cables of 18 copper wires, each insulated with rubber and cotton fabric. The cable was encased in lead tubing, which in turn was armored, and the whole was protected from moisture by a covering of tarred hemp cord. A circuit breaker in the hoisting house was said to operate readily.

Advocates of incendiary origin of the fire pointed out that a previous fire in the mine had been proved of incendiary origin, that the fire spread very rapidly in heavy timbering, and that footprints had been discovered in a drainage tunnel below the shaft collar. Against this was the difficulty of anyone climbing 3,000 feet up the manway without discovery; moreover, other places in the shaft nearer the surface could have been fired more easily and probably with greater damage to the mine.

The following points stand out in this fire as a guide in preventing future loss of life in such circumstances:

1. Men in the mine should be warned immediately.

2. An attempt should be made to hoist them.

3. All underground doors that can be reached should be opened to short-circuit the air; or all of them, including those along every level, should be closed to confine the fire within the shaft and smother it.

4. The fan should be readily reversible.

5. Doors should be so hung and arranged to remain closed when air is reversed.

6. Stoppage of the fan is of debatable value; unquestionably, the natural draft of the fire in such an instance would reverse the normal downcast tendency of the Argonaut shaft.

7. Timbered shafts should be fireproofed or fire-protected or at least the timbered stations fireproofed. Particularly, the space around electrical devices and switches should be protected against fire.

8. Every mine should have an organization for preventing and controlling fires, as well as fire-fighting equipment and a good water supply immediately available. Magma Mine Fire, Superior, Ariz.

A fire in the No. 2 shaft of the Magma mine, Magma Copper Co., about 3 a. m. November 24, 1927, caused the death of 7 of the 49 men in the mine at the time of the fire. The mine was developed by 5 shafts; No. 2 was 2,700 feet deep and Nos. 3 and 5 shafts 2,550 feet. Shafts 2, 3, and 5 were connected on the 2,550-foot and other levels. The No. 2 had 3 compartments, 2 for hoisting and 1 used as a manway; it also contained electric power and light lines.

An

Ventilation of the Magma mine at the time of the fire was directed by 3 surface and 3 underground fans, as well as various small blowers. exhaust fan with a capacity of about 95,000 cubic feet per minute (c. f. m.) exhausted from No. 4 shaft but had been shut down a few minutes before the fire. Another exhaust fan at No. 1 shaft ventilated the upper levels of the mine. Shafts 2, 3, and 5 were intakes.

About 3:30 a. m. the fire in No. 2 shaft was discovered by the shift boss, who was investigating the continued steady ringing of the electric bells in both hoisting compartments of the shaft. He found smoke at the 1,200-foot level and by signaling with the pull bell was returned to the 500 level, where he carried the cage tender, who had been overcome by gas, through the ventilation doors and reported the fire. Shortly afterward a cage with one man on it was lowered; he died, presumably from burns or suffocation, and the cable was burned off. The men in the mine smelled smoke, and most of them proceeded to No. 3 shaft, where they were quickly hoisted. Some men came to the 2,200 station and saw the fire roaring up the shaft, but no smoke was coming out into the station. They were unable to attach a hose to the fire connection because it was at the shaft and in the fire.

386912 0-57--2

The fire in the No. 2 shaft was controlled and eventually extinguished by streams of water turned down the shaft from two levels.

The No. 2 shaft had been gunited and concreted in part; but from the 1,600 level to the bottom it was timbered without fire protection, except at the stations, which were gunited to the 2,000 level. Guniting had been discontinued because of its stated tendency to promote and conceal timber decay. Gunited station timbering was fired during the shaft conflagration and continued to burn for days within the concrete shell after the main fire had been extinguished.

The fire evidently originated at or near the shaft at the 2,250 station, which was timbered and dry; the shaft timber was also dry. Oily waste at the carrepair station near the shaft ignited by a carbide lamp or possibly a cigarette butt was the origin of the fire; a transformer, a motor-driven fan, and light and power wiring, all at the 2,250 station, are also suspected.

The Bureau of Mines has drawn some 19 conclusions from this fire; the more important of which follow:

1. All main working shafts and stations, particularly downcast shafts or shafts in which men are handled, should be concreted or otherwise rendered fireproof or fireresistant.

2. All electrical equipment should be placed in a fireproof location; if feasible, it should not be in or near shafts or shaft stations.

3. Stations and all workings should be kept clean of all flammable material, and refuse should not be allowed to accumulate in a mine.

4. Placing of waterlines on shaft stations, as was done at Magma, undoubtedly prevented much damage to the Magma mine. Connections for hose attachments, however, should be at least 50 feet from the shaft in order that they may be reached during a fire in the shaft.

5. Underground electrical wiring and equipment should be placed even more carefully than surface installations and should be inspected at least monthly by a competent electrician. Any defects should be remedied without delay.

6. If smoking is allowed underground it should be limited to prescribed areas in the mine where a minimum fire hazard exists; preferably smoking should not be permitted in dry timbered areas.

7. During the Magma fire the gunite definitely acted as a fire retardent. Even when the fire burned the gunite-timbered region, the progress of the burning appeared to be retarded to such an extent that there was a minimum of caving as compared with the large amount in ungunited timbered regions. If the No. 2 shaft had been entirely gunited or concreted and the station at the 2,200-foot level had been gunited, the fire might not have started.

8. It is dangerous to send men down on a cage when there is fire in a timbered shaft, even though the shaft is downcast. Fire may quickly climb up a downcast timbered shaft and convert such shaft into an upcast, even when the shaft is damp or fairly wet. 9. The escape of most of the 43 underground workers who came out alive is credited to the excellent ventilating system in the Magma mine; the foresight of the company in having 3 downcast shafts with hoisting equipment in them deserves high commendation.

As evidence that the improbable sometimes happens, 3 days after the fire in the No. 2 shaft started and when it was virtually under control, No. 1 shaft caught fire, although there was no possibility of fire being transmitted from the No. 2 shaft to the No. 1 shaft. This second fire apparently started from embers dropping down the shaft from a surface fire built near the shaft by a watchman on a cool night. This shaft contained no wiring or electrical equipment. Water could be turned into the shaft both from a water tank on the hillside just above the collar of the shaft and from the fifth level. The fire was controlled in a few hours. During the time it burned, however, there was considerable danger that the fire might reach the magazine, which contained 65,000 No. 8 detonators, in the 200 station near the No. 1 shaft. To avoid this, an oxygen breathing apparatus crew removed the detonators to the outside. Glenn Mine Fire, Placer County, Calif.

A fire originated in some unknown manner in the wooden surface structures near the portal of the Glenn mine of the Capital Glenn Mining Co. on July 14, 1930, about 10:15 a. m. (fig. 3).

This mine was an underground placer property operated through adits driven into the hillside to recover the auriferous gravel from an old stream bed. The uppermost adit, the part of the mine then working, had been driven 1,121 feet from the portal; about 758 feet from the portal it connected with the middle or Moss adit by means of an incline dipping about 15°. The Moss adit was part of some old workings of a similar nature but was not kept repaired.

The ventilation was natural; fresh air entered the top adit at a velocity of nearly 200 f. p. m., followed down the incline, and left through the Moss adit and its connections.

The surface compressor house and shop building was about 25 feet from the portal of the upper adit, to which it was connected by a snowshed. The snowshed extended to the edge of the dump, connecting with the powerhouse about 75 feet from the end of this shed.

When the fire started no one was near the portal of the adit on the surface, and five men were working at the faces; these men tried to escape by going down the incline and out the Moss adit but were overcome and died in the attempt.

The fire burned all of the structures on the surface near the portal and about 70 feet of timbered adit inside the portal, jumped an untimbered gap of 63 feet, and ignited other timber sets; on account of the wetness of these sets, the fire died out when the timber at the portal was consumed.

No fire-fighting equipment was available at or near the mine, and equipment of the United States Forest Service was brought in to extinguish what was left of the fire.

Like many small properties, little or no consideration had been given to the possibilities of fire and its results; consequently no protection had been provided or plans made for combatting fire or preventing smoke from entering the mine.

Sunshine Mine Fire, Kellog, Idaho

The Sunshine mine fire occurred in December 1945 and resulted in a loss of 1 million dollars principally from loss of production and payment of direct costs in fighting the fire. The fire was confined to mined-out workings and was extinguished by sealing and flooding the lower levels. No injuries or loss of life occurred. The fire originated off the inclined shaft station on the 2,900-foot level when a short circuit in the battery-charging station set fire to the surrounding timbers. The fire started over the weekend when the mine was idle and was not discovered until Monday morning. The ventilating air current

carried sparks for a distance of 300 feet along an untimbered drift; these ignited the connecting raise to the 3,100-foot level, which was heavily timbered. When discovered on the 3,100-foot level, the fire had reached major proportions. Mine Fires in Foreign Countries

The greatest loss of life from metal-mine fires occurred in recent years in foreign countries, notably, the Braden Copper Co., Chile, South America, where 355 men were killed by carbon monoxide, and the Dolores mine, Argangueo Unit, American Smelting & Refining Co., Angangueo, Mexico, April 1953, where 35 men were killed by carbon monoxide.

The Dolores mine fire started in a timbered raise and was believed to have been caused by sabotage, open lights, or smoking.

The fire disaster in Chile, South America, occurred when a drum of oil exploded in an underground blacksmith shop near the main portal, which was in intake air. A high concentration of carbon monoxide was carried to all parts of the mine within a few minutes.

CAUSES OF MINE FIRES

Most metal- and nonmetallic-mine fires may be grouped under the following headings:

1. Electric wiring and equipment.

2. Open lights, flame, and smoking.

3. Welding and cutting.

4. Spontaneous combustion.

5. Explosives and blasting.

6. Heating appliances.

7. Ignition of flammable dusts, gases, vapors, and liquids.

8. Incendiarism.

9. Miscellaneous.

ELECTRIC WIRING AND EQUIPMENT

The latest available data indicate that 55 to 65 percent of presentday metal- and nonmetallic-mine fires owe their origin to electricity. This percentage is likely to increase with the widening use of electric locomotives, pumps, hoists, blower fans, scrapers, drills, and like equipment. Some examples of fires caused by electricity follow:

1. A timber in a shaft gave way, breaking electric wires; timbers were ignited by an electrical short circuit.

2. Fire was caused by contact of a heated electric-light globe with some "dope" used for a belt.

3. A fire was caused by a spark from a short circuit in the hinge on a knifetype trolley switch.

4. The contact of a trolley wire with the cap of a sagging set of timber in a wet drift caused a smoldering fire, with dense smoke.

5. Fire was started by the contact of electric wires with 12- by 12-inch timber, probably due to defective insulation.

6. A small transformer and a starting compensator "ran hot," setting fire to a wooden frame.

7. A short circuit in the electric-power cable set fire to a timber in a wet shaft.

8. A fire was caused by an overheated resistance on an electric scraper hoist.

9. A trolley wire fell and heated, causing the insulation on the feeder wire to burn, and the burning insulation started a fire in the shaft. The ground was insufficient to operate the circuit breaker at the shaft.

10. Current was left on the controller of a hoist, the hoist motor became overheated, and the timber foundation began to burn.

11. The wiring at an electrically operated blower fan started a fire when squeezing ground caused short circuiting of the wires.

Bird, J. H., and McGuire, L. H., Report of Mine Fire and Rescue and Recovery Operations, Dolores Mine, American Smelting & Refining Co., Angangueo Unit, Angangueo, Michoacah, Mexico: Bureau of Mines unpublished rept., June 29, 1953, 210 pp.