Organization, administration, and regulation-Continued. Administration__-. Accident-liability insurance_ Mine regulations-- Appendix. Index ILLUSTRATION Fig. 1. Notice posted at shaft station as safeguard to miners__. Page 134 135 136 138 139 114 Mining is an occupation more hazardous to life and limb than many others because it is carried on underground and hence in confined places. Besides the possibility of those accidents that may happen in surface industries using machinery and mechanical trans- port, there are the additional and greater dangers of falls of ground from the roof or sides, not only in the working places but also along the roads the miners use in going to and from work-dangers that are especially acute in pitching working. There are also the dan- gers inseparable from the use of explosives. In the United States in 1925 the fatality rate for all metal mines per thousand 300-day workers was 2.99 as compared with 1.78 for quarries, 1 for ore- dressing plants, and 0.64 for smelters. In comparison with metal mining, coal mining presents additional dangers because more or less dangerous amounts of inflammable gas enter the workings. In 1925 the fatality rate for coal mines per thousand 300-day work- ers was 4.65, as compared with 2.94 for copper mines, 3.83 for gold and miscellaneous metal mines, 2.54 for iron mines, and 3.32 for To prevent or decrease accidents in mining, especially coal min- ing, is a far more complicated problem than in surface industries, Because the prevention of accidents in coal mines is difficult, the At the beginning of this century accidents became increasingly numerous because of natural conditions due to increasing depth, more gas entering the mines, and roof pressure growing heavier, and also because of the growing use of electric power and, in some districts, of blasting off the solid instead of hand mining. Disastrous explosions happened so frequently that in 1908, as the result of a series of particularly bad coal-mine disasters in the preceding year, Congress was petitioned to have the Federal Government investigate the causes of coal-mine explosions and other accidents. In consequence, a technologic branch of the United States Geological Survey was established to undertake the work. Two years later the work was transferred to the Bureau of Mines, which was established to conduct investigations for the increase of safety in all kinds of mining and mineral preparation and to investigate the economic problems of all the mineral industries, including metallurgy, the mining and preparation of nonmetallic minerals, and the petroleum industry. This report deals solely with accidents in coal mines and with the means of prevention that have been determined and officially approved by the bureau or have been tentatively suggested by certain members of the bureau. Mining, mechanical, and electrical engineers, chemists, physicists, and statisticians who have had experience in problems of mine safety have been consulted, but where the report deals with questions and policies not officially as yet decided on it necessarily reflects to a certain extent the views of the writer. The report aims to give only concise recommendations based on mine investigations and on laboratory work. References will be made to more complete information when that has been published. ACKNOWLEDGMENTS Valuable information for use in this handbook has been freely given by many members of the bureau and has been thankfully received by the author. To make personal acknowledgments to all is not feasible, but those named below have approved those parts that deal with subjects in which they are concerned technically and administratively: O. P. Hood, chief mechanical engineer; L. C. Ilsley, electrical engineer; D. Harrington, chief engineer, safety division; J. W. Paul, senior mining engineer; R. R. Sayers, chief surgeon (physiological investigations); A. C. Fieldner, chief engineer, experiment stations division; Charles E. Munroe, chief explosives chemist; G. St. J. Perrott, physical chemist (in charge of explosives laboratory and testing of explosives); S. P. Howell, explosives engineer; William Yant, associate chemist (gas laboratory); J. J. Forbes, chief engineer, safety instruction section; and W. W. Adams, mine-accident statistician. Special indebtedness is acknowledged to the late Samuel Sanford, editor of the bureau since its organization and a man of profound knowledge and sympathetic understanding, who gave valuable service in the preparation of this handbook. ACCIDENTS IN COAL MINES, BY CAUSES Table 1, compiled by W. W. Adams, shows for a 10-year period, 1915 to 1924, the percentage of men killed yearly by 21 main causes, above and below ground, at coal mines (including anthracite mines) in the United States; it also gives the actual number of deaths from each cause in 1924 and 1925. TABLE 1.-Fatalities by causes, 1915-1924 and 19251 Killed per thousand 300-day workers in 1925, 4.65; killed per 1,000,000 tons of coal produced in 1925, 3.84; number of men employed underground in 1925, 627,109; number of men employed surface and underground in 1925, 748,805. 1 Adams, W. W., Coal-Mine Fatalities in 1926: Bull. 283, Bureau of Mines, 1927. During the 10-year period, as the table shows, more than 92 per cent of the fatalities were underground or in shafts. The first 5 causes of fatalities underground cover 82 per cent of all fatalities, and falls of roof and coal include 48 per cent of all accidents, or 52 per cent of all fatalities underground. Explosions in the 10-year period caused only 12 per cent of all accidental deaths; but, on the other hand, in 1924 they caused 22 per cent. COMPARISON OF ACCIDENT RATES IN MINES Two general methods of comparing coal-mine accident statistics are used: (1) By annual accident rates per thousand employees, or (2) by the number of accidents in relation to the output of coal. Under the first method the comparisons are made on the basis of the deaths or fatalities in the respective occupation or mine, per 300-day men employed, either (a) in the particular occupation, or (b) in all occupations at the mine (in other words, the total number employed). An alternative to using the number of men employed for death or injury rates is to use the shifts worked per annum or hours worked per annum. The second method is to compare the number of accidents on the basis of the yearly deaths or injuries (in the respective occupations, mines or mining districts, or States) per million tons of coal produced, or the reciprocal, tons mined per death or injury. The first method is ordinarily used and, in fact, is the only way of comparing the accident rates for the different mining conditions in various coal fields; it does not, however, consider the efficiency of the miners or the organization and mechanicalization of mining— for example, the employment of an unnecessary number of men on dead work, or the noninstallation of labor-saving devices and methods. The second method combines but leaves uncertain the relative importance in hazard rating of three factors: (1) Natural mining conditions that affect ease of mining; (2) combined efficiency of men and machinery employed in producing coal; and (3) relative care or carelessness of management and miners. It is obvious, for example, that a thin or a pitching bed, or one with many rolls or with a bad roof, must employ more men per unit of output than a mine in a level thick bed, hence accident rates on a tonnage-production basis do not necessarily reflect the relative care taken. Neither the first nor the second method gives the complete picture, but the first method better indicates the degree to which voluntary safety rules or State regulations have been observed. Table 2 uses the second method, the number of deaths in comparison to the gross production, for comparing fatality rates among coal miners in the different States. Figures are also given to show the average daily production per man per day in 1925. |