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By C. W. Owings

A few of the more progressive mining companies have taken precautions to safeguard employees or man-trips. Specially constructed men-cars -have been provided with special devices or mechanisms to stop the cars on slopes, if the hoisting cable should break. Cars have been equipped with safety chains to connect and hold them together if a coupling should break. Steel frames covered with heavy wire netting have been placed over cars to reduce injuries to the riders from roof fails on slopes. A safety cable passing from the front car to a point above the cable socket on the slope hoisting cable is used frequently as a precaution in case the socket loosens o the main cable breaks at the socket. Such devices are commendable, but the percentage of man-cars and man-trips protected is relatively small - entirely too small. Man-trips that travel level haulage roads are rarely protected safety devices, and haulage roads are seldom inspected by mine officials to determine the condition of roof and ribs.

Jan 1, 1935

By Frank E. Cash

The work of the United States Bureau of, Mines is concerned primarily with the prevention of accidents in the mining, petroleum, and allied industries. This report analyzes the fatal accidents in the coal mines of Tennessee and gives the pertinent factors in tabular and descriptive form, with interpretations and suggestions to operators, workers, and the State Division of Mines for the future prevention or reduction of accidents in coal mines. ACKNOWLEDGMENTS This study was made possible through the cooperation of A. W. Evans, chief mine inspector of Tennessee, and his secretary, Miss Hiliary Penny, who made available the department records and assisted in the segregation and assembly of the data.

Jan 1, 1935

By Frank E. Cash

As a part of its safety program the United States Bureau of Mines has fostered the development, use, and improvement of portable electric mine lamps. Although there is still need for better illumination in mines and the replacement of open lights has been slow, improvement in electric cap lamps and increase in their use indicate one phase of recent progress toward safer and more efficient mining This report is the result of a recent survey of electric-lamp installations in the Alabama mining; district; it shows the misuse, increase in use, and relation to certain classes of accidents of these installations.

Jan 1, 1935

By C. E. Rork

This paper discusses various mechanical improvements that have been gradually incorporated in the copper-willing plants of the Southwest daring the past 14 years, power plants for concentrators, use of large-size units of equipment, and the effect of plant capacities on costs. The improvements in mechanical equipment and plant design have contributed in the reduction of operating costs; in some instances a saving in the capital cost per ton of daily capacity milled has resulted.

Jan 1, 1935

By Oliver Bowles

This paper is the third of a series of reports on asbestos prepared by the Bureau of Mines. The reports already issued contain general information, including descriptions of deposits throughout the world.3/ The present paper deals chiefly with milling and marketing. Many grades of asbestos are marketed, and an important phase of milling is the grading of fiber; these subjects therefore are related so intimately that contiguity in their treatment is fully justified. Although the Bureau of Mines is interested primarily in the mining and preparation of raw materials, the fabrication of asbestos products has attained such importance in the United States that brief reference to processes of manufacture is included. CLASSIFICATION OF FIBER Canadian asbestos fibers are divided into three main groups - crudes, mill fibers, and shorts. The term "crude" is applied to fiber of spinning grade measuring three eighths inch or longer, that is. hand-cobbed and not passed through a mill. Mill fibers are obtained by crushing and beating the fiber-bearing" rock, until the, asbestos is freed and, then removing the fiber from the rock by screening or air separation. Shorts are the lowest grades of mill products.

Jan 1, 1935

By D. Harrington

The experience of the past 2 years has demonstrated clearly that mine explosions with heavy loss of life can be prevented. The investigations of the Safety Division of the United States Bureau of Mines disclose that during the fiscal year 1934 there were only 28 deaths from mine explosions in the United States, and during the fiscal year 1935 there were 54 deaths, a very favorable reduction when compared with an average death toll of 265 from this cause during the 20-year period prior to 1929. Although the frequency of occurrence of explosions has not decreased greatly during the past 7 years, there has been a marked decrease in severity, indicating that the coal-mining industry is taking more effective precautions to prevent the spread of explosions. A number of large coal-producing States, which in past years have experienced numerous disastrous explosions, have been free from such disasters for continuous periods of as much as 5 years or even longer. A study of several hundred mine explosions occurring in the United States during the past 10 years or more indicates that the factors mainly responsible for these explosions are inadequate or defective ventilation and disregard of the hazards from explosive gas. Both of these factors are subject to control, and if controlled it is safe to say that deaths from explosions would be reduced to a negligible number as relatively few explosions are now initiated by dust.

Jan 1, 1936

By D. Harrington

Probably over 95 percent of the coal production of the United States depends upon the use of explosives before it can be placed in the railroad car at the mine, and up to the present time it has been impossible to obtain Pry kind of practicable explosive that isn't dangerous unless handled carefully. In other words, no "foolproof" explosives have been found to date and inspection of the accident records of the coal mines of this country indicates that the use of explosives in coal mines has taken a sad toll of lives. ACCIDENTS PROM EXPLOSIVES IN COAL MATES Of the 2,000 to 2,500 persons killed annually in the coal mines if the United States, 100 to 125 have been killed from explosives without an explosion of gas or dust; these accidents have been due to misfires, hangfires, premature blasts, or accidental setting off of explosives through carelessness or otherwise (but chiefly through carelessness in some form). In this type of accident the flame character of the explosive is not necessarily involved, although an unexpected or premature blast is initiated much more easily with black blasting powder, which has a long flame, than with a permissible explosive, which has a flame much shorter and of briefer duration. By far the greater number of such accidents are caused by black blasting powder or dynamite rather than by permissible explosive.

Jan 1, 1936

By J. W. Paul

The United States Bureau of Mines has made a study of roof control in 68 mines operating in the Pittsburgh coal bed in Pennsylvania, West Virginia, and Ohio. In making these studies, much information was also obtained on various exact methods of development and pillar extraction as practiced by this large group of mines. It is proposed in this paper to describe these methods, by which this group of mines in 1931, a year of reduced industrial activity, produced 28,123,000 tons of bituminous coal - 7.4 percent of the national production for the same year and an amount equal to the combined production of the coal mired in the States of Alabama, Colorado, New Mexico, Utah, and Wyoming. The results of these studies, insofar as they pertain to the prevention of injuries from falls of roof, have been published by the Bureau of Mines. In this paper only a few mines typical of each system will be described; however, should the reader be interested in other details with respect to these mines, he may refer to the following publications: T.P. 522, 1932, 43 pp. Falls of roof and coal in mines operating in the Pittsburgh coal bed in Marion and Monongalia Counties, W. Va., by J. W. Paul and J. N. Geyer.- A study of nine mines in these two counties of northern West Virginia.

Jan 1, 1935

By William O. Vanderburg

The fluorescence of many minerals, when excited by different wave lengths, of ultraviolet radiation, has long been recognized as a spectacular laboratory phenomenon. Since the original display in the British Museum, the phenomenon has been used frequently for educational purposes and public demonstrations. Its practical application for the rapid detection of certain minerals in ores and mill products at the zinc mine at Franklin, N. J., has been described.3 Due to technical improvements in ultraviolet-radiation apparatus, fluorescence has found a new field of application in the tungsten-minim; industry. Although fluorescence of scheelite (calcium tungstate) has been known for a number of years, the practical application of the phenomenon is the outgrowth of a program of cooperative research conducted by Ott F. Heizer, manager of the Nevada-Massachusetts Co., Inc. , Mill City, Nev., and Dr. Paul F. Kerr of Columbia University. Special portable lights for fluorescing scheelite have been developed and utilized in underground geological work. Thanks are due Ott F. Heizer for permission to publish data included in this paper.

Jan 1, 1935

By J. R. Thoenen

This circular is part 5 of the third paper (entitled "Excavation") of a series summarizing the technical problems involved in the production and preparation of sand and gravel. Part 1 discussed the use of power shovels, draglines, and excavator cranes; part 2, power scrapers, slackline cable-way excavators, and hydraulic monitors; part 3, hydraulic, clamshell, ladder, and dipper dredges; and part 4, haulage systems in general, with particular reference to locomotive and car, hoist and car, and remote-control systems. This circular discusses the use of motor trucks, conveyor belts, pumps end pipe lines, barges and towboats, and aerial trams. MOTOR-TRUCK HAULAGE During recent years motor trucks have gained considerable ground as a successful competitor of locomotive haulage for quarries and gravel pits. Often where trucks have displaced locomotives and cars the operators readily admit an increase in both labor and total haulage operating costs but point to some other advantage as offsetting the extra expense. In other instances haulage costs have beep reduced by the use of trucks. In still others operators, having replaced locomotive haul with trucks, have again returned to the earlier method. Obviously gasoline-driven motor trucks cannot successfully compete with other types of haulage under all conditions. The apparent' growth in the number of advocates of truck haulage, however, indicates that it has passed the experimental stage and become a permanent competitor to other tyres.

Jan 1, 1936

By McHenry Mosier

The object of this investigation is to determine the field for the use of detachable bits in metal mines of the United States by correlating the data developed through the experience of mines using these bits. Most of the metal-mining districts in the Middle Western and Eastern States already have been visited. The purpose of the present circular is to define the problem and to discuss the factors that must be considered in order to determine, under different operating conditions, the advantages and disadvantages of this type of bit. Some of the data obtained to date are presented to emphasize points made in the discussion. It is hoped that, as the study progresses, a great many data on drilling will become available. It is evident that since in some cases these data will be confidential they cannot, therefore, be published except as they may be included in average figures covering several different mines. Some data already secured are of this nature, Although considerable information on drilling operations has been gathered at different mines, there were only a few instances in which there were available complete data on all the factors entering into the total cost of drilling with detachable bits and with conventional bits on regular drill steel.

Jan 1, 1936

By George S. Rice

The following paper was presented at an International Conference on Mine Safety Research held at Dortmund, Germany, September 23-28, 1935, inclusive. This conference was attended by representatives of Belgium, France, Germany, Great Britain, and the United States ands by invitation, Czechoslovakia, Poland, Spain, and Russia. The first international conference of representatives of mine-safety, research stations was held the United States Bureau of Mines Pittsburgh Experiment station in 1912 .4/

Jan 1, 1936

By J. R. Thoenen

This circular is part 6 of the third paper (entitled "Excavation") of a series summarizing the technical problems involved in the production and preparation of sand and gravel. Part 1 discussed the use of power shovels, draglines, and excavator cranes; part 2, power scrapers, slackline cableway excavators, and hydraulic monitors; part 3, hydraulic, clamshall, ladder, and diaper dredges; part 4, haulage equipment, particularly industrial cars with locomotive or hoist as the motive power; part 5, conveyor belt, motor truck, pump and pipe line, towboat and barges, and aerial-trams haulage. This circular discusses the application of these various types of equipment to the different types of sand and gravel deposits and contains a reference bibliography. It completes the discussion of excavating problems.

Jan 1, 1936

By Gloyd M. Wiles

The property of the Park City Consolidated Mines Co. is situated in the northeast part of the Park City dining district 1 mile east of the town of Park City. The elevation at the collar of No. 1 shaft is 7,250 feet. Park City is a town of approximately 4,500 population lying about 30 miles east of Salt Lake City. The two are connected by an oiled State Highway, which is cleared of snow in winter and maintained in first-class con¬dition by the State throughout the year. The district is served by branches of the Denver & Rio Grande Western and Union Pacific Railroads, each operating on a daily' schedule, except Sunday. These two railroads have constructed 1 ½ miles of joint track from the town to the Park City Consolidated Mines Co. loading tipple, located 200 feet from the portal of the adit that leads to No. 1 shaft.

Jan 1, 1936

By Oliver Bowles

The manufacture of lime is one of the oldest industries. Plants are distributed widely and furnish an essential raw material for numerous industries. The use of lime by the building trades, in agriculture, and in hundreds of manufacturing and chemical processes has created demands for a large production and has necessitated exhaustive research on methods of manufacture and uses. The bibliography of lime is an extensive one, but for the most part each publication has dealt with only certain operations. The purpose of this paper is to present a general picture of the industry as a whole. The abundant literature has been abstracted and quoted freely, and the National Lime Association has rendered valuable assistance in furnishing data for certain sections. Publications containing more detailed information on the various branches of the industry are referred to in the footnotes and in the bibliography.

Jan 1, 1936

By E. D. Gardner

During the summer of 1935 a plan was proposed by which the Government should establish custom sampling plants for gold and silver ores in the mining districts of the West, where the construction of such plants would be justified as an unemployment relief measure. It was known that in many districts prospectors and small operators had small lots of smelting ore that could not be marketed for lack of sufficient capital to get out enough ore at a time to make carload shipments to distant smelters. Moreover, considerable ore of milling grade was available in many districts in which there were no custom milling facilities. It was felt that. accurate sampling and the classification and consolidation of small lots of ore produced from prospects and small mines, with quick cash returns to the shippers on a nonprofit basis, would stimulate the working of small gold and silver properties: Idle mines would be put to work, and there was a possibility that some of the prospects could be developed into regularly producing mines. Each sampling plant was to be centrally located so as to serve the greatest possible number of mines and prospects. Wherever possible, the plants were to be built on a railroad, is ore of smelting grade accumulated, it was to be shipped to a smelter in carload lots. Where a plant was not on a railroad, smelting ore was to be trucked to the railroad after being sampled.

Jan 1, 1936

By E. D. Gardner

Ore and concentrate are transported on, the surface at western mining districts by (1) railroads, (2) surface trams, (3) aerial trams, (4) trucks, and (5) wagons, and (6) on the backs of animals. The daily and ultimate tonnage to be moved is the principal factor governing the selection of the method of transportation. Railroads are preferred when large tonnages are to be hauled over relatively long distances. The mine-haulage system may be extended or surface trams built to the mill or shipping point if a practical track grade is possible and if the distance is relatively short. Aerial trams have a special field of usefulness for transportation over steep or excessively rough terrain.

Jan 1, 1936

By E. D. Gardner

This is one of a series of papers describing mining and related subjects affecting mining in western mining districts and mineralized areas. The parts of this paper pertaining to current production, mining and milling methods and practices, and general conditions affecting mining were collected principally during a field survey made in May 1935. Some original data obtained on previous visits to the area are also included. The history, geological background, and past production of the mines and district are largely abstracted from previous publications, for which due credit is given later in the test. The principal districts in the Black Mountains are the Oatman or San Francisco and the Union Pass or Katherine. This range contains the principal producing mines of the State, in which gold is the only important metal. Although the total production of gold is relatively small as compared to other districts where the precious metals are obtained as a by-product in copper min¬ing, the area is one of considerable economic importance to the State.

Jan 1, 1936

By William O. Vanderburg

This paper gives the results of a reconnaissance of the mining districts in Pershing County, Nev., made from March 9 to April 1, 1936. During the field work nearly all of the mining districts in the county were visited, and considerable data were obtained on active and inactive properties. The report covers the location of the various mining districts, nature of the deposits, information on past

Jan 1, 1936

By D. Harrington

Near the close of the nineteenth century electricity was introduced underground, and the mining industry automatically was confronted with another potential source of fatalities and injuries to mine workers. Electricity has become an increasingly vital factor in the production of goal, particularly in recent years, because of the greatly extended mechanization that has taken place underground. The enlarged use of electrical equipment for cutting, loading, and hauling coal unquestionably increased the potentiality of shock and explosion hazards underground. Electricity may be used in coal mines with minimum danger if electric equipment and power-carrying wires are chosen properly and installed and kept protected by proper safeguards; on the other hand, if vigilance is relaxed in the slightest degree accidents may result. Electrical accidents are caused chiefly by direct contact with electrical equipment or power-carrying wires, by ignition of explosive gas or dust, and by fires of electrical origin. Electricity now ranks fourth as a cause of coal-mine fatalities, not including deaths from explosions or fires of electrical origin.

Jan 1, 1936