ACCIDENTS FROM HOISTING AND HAULAGE IN METAL MINES

Metal-Mine Accident-Prevention Course-Section 31

INTRODUCTION

PURPOSE AND SCOPE

1

This publication is the third in a series of miners' circulars that will cover various phases of accident prevention in metal and nonmetal mines; these circulars constitute a text book for courses of instruction on accident prevention in metal mining. They are intended to serve as a general reference to which may be added other material applicable to the district in which the course is presented.

This section deals with the occurrence of hoisting and haulage accidents, their causes, and proved preventive measures that may be used to guard against them and reduce the seriousness of injuries to persons involved. In addition to illustrations included in the text, a large number of lantern slides are shown in accident-prevention classes.

Other circulars in the proposed series are:

Accident Statistics as an Aid to Prevention of Accidents in Metal Mines (Miners' Circular 51); deals with general statistics on accidents in metal and nonmetal mines, including causes, costs, and the uses of investigation and report of all accidents.

Accidents from Falls of Rock or Ore in Metal Mines (Miners' Circular 52); discusses the selection of mining methods to minimize the hazard of falling ground, the use of various types of support, and the protection of miners from falling ground.

Explosives Accidents in Metal Mines (Miners' Circular 54); gives information on accidents due to storing, handling, and using explosives in mines and precautions by which they can be prevented.

Electrical and Mechanical Hazards in Metal Mines; covers accidents from these causes and their prevention. Accidents from falls of persons are also discussed in this section.

Fires, Gases, and Ventilation in Metal Mines; explains causes of mine fires and the measures used to prevent them; describes gases found in mines and methods of detection, and discusses necessity for and standards of proper ventilation.

Health and Other Accident Factors in Metal Mines; includes data on dust hazards, means of protection and sampling devices, protective clothing and equipment, illumination, supervision and discipline, and safety education for miners.

These seven miners' circulars do not contain all the material that may be desired on any of the various phases of accident prevention in metal mines, but it is hoped that they will be inclusive enough to serve as a basis for discussions. To these may be added supplementary material of particular interest in the field where the course is being presented.

1 Work on manuscript completed October 1944.

ACKNOWLEDGMENTS

Accident statistics used in this circular were prepared with the assistance of W. W. Adams and F. J. Kennedy of the Accident Analysis Division of the Bureau. Drawings and photographs for the illustrations were prepared by L. F. Perry and G. L. Henneman of the Graphic Section of the Office of Minerals Reports of the Bureau. J. H. East, Jr., and D. O. Kennedy reviewed the manuscript of the circular and gave many helpful suggestions.

IMPORTANCE OF HOISTING AND HAULAGE ACCIDENTS

Hoisting and haulage accidents generally entail greater economic loss than any other type of mine accident except fires. Most accidents of this type interrupt production and often result in damage to property without loss of life or limb; on the other hand, injury to persons may occur with or without damage to equipment. The economic loss involved in haulage accidents should justify special effort on the part of the mine management to reduce the hazards; in addition, there is an obligation to provide safe working conditions for employees. Although the initial expenditure for improvement of hoisting and haulage equipment may not seem to be justified, the loss of production and compensation payments over an extended period, due directly or indirectly to improper or poorly maintained equipment or to poor practices or procedures, probably would more than pay the cost of the improvements in installation or equipment as well as in the revision of practices or procedures of doubtful safety.

The loss of production caused by one serious shaft accident often would pay for the installation of safety devices that would have prevented the accident. Haulage injuries as a rule are serious; the smaller injuries may involve feet, fingers, or hands, but the number of accidents involving broken bones, loss of fingers, or more serious permanent disabilities is relatively large, and the number of fatalities from haulage accidents is anything but negligible.

ACCIDENT RATES FROM HOISTING AND HAULAGE ACCIDENTS

Hoisting and haulage accidents at metal and nonmetal mines caused about 13.9 percent of the fatalities and 12.5 percent of the nonfatal injuries during the 3-year period 1940-42. The number of these accidents for each year and the percentage of the total number for the period are shown in table 1. The proportion of fatal to nonfatal accidents in hoisting is high, as are those from haulage in open-cut mines. Nonfatal injuries from underground haulage represent 9.5 percent of the total injuries, but only about 1 in every hundred is fatal, which is lower than the ratio of 1 fatal to each 70 injuries for metalmine accidents as a whole. The frequency rates, percentages of accidents from hoisting and haulage to total accidents, and number killed and injured are shown in tables 2, 3, and 4, for 1931 to 1942. Hoisting fatality rates have decreased in the 5 years from 1938 to 1942 as compared with the rates from 1931 to 1937. Injury rates from hoisting have not shown any notable change. Underground-haulage-accident rates for both fatalities and injuries have not improved since 1931. Open-cut haulage-accident rates fluctuate considerably year by year, largely because of the small number of accidents on which the rates

are computed. No appreciable change in the hazard from haulage at open-cut mines is apparent over the period covered by table 4. TABLE 1.-Accidents from hoisting and haulage, 1940, 1941, and 1942,1 United States metal mines

1 Adams, W. W., and Kolhos, M. E., Metal- and Nonmetal-Mine Accidents in the United States, 1940: Bureau of Mines Bull. 450, 1942, 51 pp.

Adams, W. W., and Kennedy, F. J., Metal- and Nonmetal-Mine Accidents in the United States, 1941: Bureau of Mines Bull. 457, 1944, 53 pp.

Adams, W. W., and Kennedy, F. J., Metal- and Nonmetal-Mine Accidents in the United States, 1942: Bureau of Mines Bull. 461, 1945, 81 pp.

TABLE 2.—Accidents from hoisting—underground metal mines, 1931–421

1 Admas, W. W., and Kennedy, F. J., Metal- and Nonmetal-Mine Accidents in the United States, 1942: Bureau of Mines Bull. 461, 1945, 81 pp.

TABLE 3.-Accidents from haulage-underground metal mines, 1931-42 1

1 Adams, W. W., and Kennedy, F. J., Metal- and Nonmetal-Mine Accidents in the United States, 1942: Bureau of Mines Bull. 461, 1945, 81 pp.

TABLE 4.-Accidents from haulage-open-cut metal mines, 1931–421

1 Adams, W. W., and Kennedy, F. J., Metal- and Nonmetal-Mine Accidents in the United States, 1942: Bureau of Mines Bull. 461, 1945, 81 pp.

EXAMPLES OF HOISTING ACCIDENTS

The following typical hoisting accidents are discussed briefly; and many other examples could be given from occurrences in the last several years which would cover other types of accidents from less common causes. The fundamental causes of hoisting accidents are the use of equipment designed primarily to handle ore or rock and poorly adapted to transporting men; the use of makeshift equipment without proper controls and safeguards; and unsafe practices.

1. A foreman was killed while he and a helper were being hoisted from a level where they had unloaded a storage-battery locomotive. Soon after the cage started a jar was felt, and tension was caused on the hoisting cable by an auxiliary set of lugs under the cage becoming entangled with the chairs, which had not fallen back as the cage was lifted. The tangle suddenly let go, and the cage was jerked some distance up the shaft. Both men were thrown against the roof of the cage, and the foreman fell off and down the shaft.

In this accident the chairs were not in good working order, and the doors on the cage may not have been closed.

2. A miner with a lacerated hand was being hoisted to the surface in a bucket to receive first-aid treatment. On the way to the surface he fainted and fell 320 feet to the bottom of the shaft.

The injured man should have been held in the bucket by another person. No injured person should leave a mine unaccompanied, even if the injury is a minor

one.

3. A mine laborer riding in a small skip on a 40° inclined shaft raised up and was killed when his head struck a timber in the hanging wall of the shaft.

The victim did not use the necessary precaution while traveling in skips on inclines; however, any type of conveyance is hazardous when it is possible to be killed or injured by a small change of position. A safe conveyance should be used.

4. A miner attempted to alight from a cage at a station on a vertical shaft after the signal had been given to lower the cage to another level, and the cage had started to move. He was pinned between the station floor and the top of the cage, receiving fatal injuries. The station gates were closed, but it had become customary to leave the cage gates open.

The gates were put on the cage to keep men from accidentally or deliberately exposing themselves to risks of this nature, but the safeguards were not used, and the man's actions were reckless enough to cause his death.

5. An experienced skip tender got into his usual place on the padded clamped loop of the hoisting rope with his feet on the bail of a skip operating in a shaft inclined at 22°. He pulled the bell cord, and after the skip had moved about 20 feet he fell off onto the rail and was killed by the skip before it could be stopped by the foreman, who was riding inside.

This is another example of unsafe procedure in use of skips for handling men. 6. A skip tender completed loading an ore skip at a loading pocket and gave the signal to hoist. The engineer was oiling and adjusting the hoist and did not raise the skip for several minutes. When the hoist started the engineer felt a jar after the skip had gone a few feet. He stopped the hoist, and on investigation it was found that the skip tender had been caught by the skip and instantly killed. The skip tender had evidently left his compartment and stepped onto the skip while it was waiting.

This is an example of chance taking by the skip tender; such accidents can be avoided only by the education of employees in safe methods of work.

7. A motorman and his car loader were being lowered in a 1-ton man and supply skip suspended beneath an ore skip by a 13-foot length of 1-inch steel cable which was fastened by three clips and a thimble at each end. The shaft was inclined 65°. The supply skip hung up or got off the track and then was released, falling the length of the attaching cable. The jerk pulled the dead end of the cable through the clips, and the men were killed when the supply skip smashed against timbers several hundred feet lower.

Investigation revealed that the clips were not securely fastened, and even if they had been, the number of clips used probably was insufficient to withstand the force of such a jerk.

8. A cager and a shift boss got on a cage at a level in a vertical shaft. The cager was carrying three pieces of drill steel. When the cage was lifted the lever operating the chains attached to the cage struck the drill steel, causing one length to project over the edge of the cage. This steel caught under a wall plate, and the cage was held until the steel bent and released the cage, which then jumped about 20 feet. The cager was thrown against the wall of the shaft and was decapitated and crushed between the cage deck and the wall plates. No doors were in use on the cage. The shift boss had grasped the handhold on the cage and was able to maintain his grip so that he was uninjured.

Properly fitted doors on the cage might have prevented the accident. Cages should be designed so that doors or gates can be left in place at all times. However, when cages from which the gates must be removed to handle cars are used, the gates should be replaced before men are permitted to ride.

Moreover, tools or materials that cannot be laid on the cage deck should be securely lashed in position so that they cannot possibly project beyond the confines of the cage.

Some hoisting safety problems are difficult to solve because replacement of the original shaft and the hoist installations is not feasible. In these cases special methods should be devised to guard against recognized dangers. In so far as possible, dependence should not be placed on care by the individual while riding into and out of the mine or from place to place underground.

HOISTING

HOISTS, BRAKES, SAFETY DEVICES

Certain standards of safe operation apply to all uses of hoists, regardless of the material handled and the type of opening through which it is handled. Experience has shown that these standards must be met in one form or another to give protection from serious accidents. Where some of the safety equipment mentioned in the following paragraphs is not provided, the alertness and skill of the hoistman are the only assurance against disaster. In many cases of failure of some part of the equipment, the hoistman would be powerless. Wherever possible, the fullest protection should be given men who are transported into and out of the mine by these hoists.