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By D. W. Butner

The blast -hole method for drilling and breaking ground is not new to the mining industry . For several years it has been used rather extensively in Canada , particularly in the gold mines , where it was first developed and where the major advances in the technique as applied to present - day mining problems have been made . At present , 40 mines in Canada and the United States are using the method in one form or another , and from all indications its use will increase in the future . In two California mines , blast -hole diamond drilling is now used for a part of or for all stoping operations , and in one of these it is used to some extent in development work . At the Mountain Copper Co.'s Hornet mine in Shasta County, about 50 percent of the pyritic sulfide ore produced is mined by the blast - hole method , and the U. S. Vanadium Corp. mines 80 percent of the ore produced at its Pine Creek tungsten mine in Inyo County by this method . At Pine Creek , long -hole drilling and blasting is used for mining pillars also , and in pre - stoping development . The blast -hole diamond - drilling method is not applicable to all types of ore bodies . A third property in California , the El Dorado Limestone Company , El Dorado County, tried the method for several months in 1943 and 1944 , but , owing to certain factors that greatly increased mining cost , the company soon returned to conventional mining methods .

Feb 1, 1948

By Virgil J. Stachura

The Bureau of Mines conducted a series of delayed blasting experiments at a West Virginia contour coal mine that resulted in smoother highwalls. The 17; were smoother due to reduced overbreak and inherently safer A, to reduced likelihood of rockfall. Reduced overbreak was accomplished by an increase in the highwall hole delays, which changed the effective delay pattern geometry and the direction of burden movement. The blast delays in the highwall holes were 50 to 100 ms longer than the mine's nominal design pattern (flat V, 17- by 42-ms surface delays, 200-ms in-the-hole delay). The burden movement was effectively changed from a 45* angle to 90* with respect to the highwall. The results of the blast delay changes were evaluated using terrestrial photogrammetry to generate vertical profiles at regular intervals. This evaluation showed that delay changes produced generally smoother vertical profiles.

Jan 1, 1984

By Nicholas Kyriazi

The Bureau of Mines has been developing breathing and metabolic simulator technology since 1970. Breathing simulation has been widely achieved throughout the world and used in the testing of open-circuit breathing apparatus, but satisfactory metabolism simulation has not been achieved. This situation required that the testing of closed-circuit breathing apparatus, which are the only type used in mines, be done using human test subjects. The goal was a machine that could accurately simulate both the breathing and the metabolic functions of a human being for testing of closed-circuit breathing apparatus. The advantages of using such a machine instead of a human being for testing respiratory protective devices lie in its ability to quantify metabolic input, its repeatability, and the lack of a need to deal with the vagaries of human subjects. This report will describe the breathing and metabolic simulators that have been developed and used by the Bureau over the past 15 yr.

Jan 1, 1986

By Frank E. Cash, Max S. Petersen

"INTRODUCTION Explosives have been used in ever—increasing amounts since gunpowder was invented. For hundreds of years only low explosives of the deflagrating type were used, and they were fired by means of a flame or hot object. Ben¬jamin Franklin first ignited gunpowder from a distance in 1751 by means of an electrostatic spark. Further efforts to develop a satisfactory electrical method to ignite explosives from greater distances were overshadowed by the invention of safety fuse in 1831, as this offered a relatively simple and inexpensive means of firing explosives.The discovery and introduction of high explosives of the detonating type and the invention of the fulmitate of mercury blasting cap about the middle of the nineteenth century provided the needed impetus for inventors to develop means of firing the cap by electricity. The original high-tension igniter, following Benjamin Franklin's experiment in which the detonating compound was ignited by a spark, was discarded in favor of a low-tension igniter, in which the detonating compound was ignited by a heated wire. The past 2 decades have seen considerable improvement in the design and construction of electric detonators to make them safer and more efficient, yet in spite of the improvement it is estimated that less than 50 percent of the explosives used in industry today are ignited or detonated electrically. The trend, however, is toward the use of electric methods. In recent years numerous-mining companies have introduced electric blasting exclusively at their mines as a means of improving safety and efficiency."

Sep 1, 1946

By E. L. Rawlins

The Bureau of Mines, with the cooperation of the Natural Gas Association of America, has conducted a study of leakage losses from natural-gas transmission lines. This study has shorn that surveys to determine the leakage from transmission lines lead to line repair work that not only aids in the conservation of gas, but can be made to show financial returns of large magnitude.2 In order to conduct the study, it was necessary to develop accurate and reliable methods of determining the actual leakage from pipe lines. METHODS OF TESTING Three methods that were developed and used to determine the leakage losses from high-pressure natural-gas transmission lines are: (1) The "pressure-drop" method, (2) The "metering-in and metering-out" method. (3) The "metering-in" method.

Jan 1, 1926

By A. Visnapuu

The U.S. Bureau of Mines investigated the oxidation of American Iron and Steel Institute (AISI) Type 304 stainless steel (SS) during annealing in simulated combustion products from several air-CH4 fuel ratios. Atmospheres representing air-CH4 ratios of 14:1 and 18:1 contained free 02, while atmospheres representing 10:1 air-CH, ratio did not. A Cr203 layer formed on SS samples annealed in atmospheres containing free 0, while a Cr-Fe spinel layer formed in atmospheres with no free 02. The Cr203 layer was adherent and presented a protective barrier to metal diffusion, effectively limiting oxidation of the metal substrate. The Cr-Fe spinel was not protective and allowed the diffusion of Fe through the spinel to the gas-oxide interface where it was oxidized to magnetite, which spalled from the surface. This resulted in thick scale layers on samples annealed in atmospheres containing no free 02, as compared to layers formed on samples annealed in atmospheres containing free 02. These results confirmed and explained industrial operators' observations that thick, smoky (fine spalled magnetite) scales form on SS annealed in low free-02 atmospheres, while thin protective oxide layers form on sheets in atmospheres containing free 02.

Jan 1, 2010

By J. S. Miller

The Bureau of Mines developed methods for fragmenting oil shale formations with chemical explosives to prepare oil shale for in situ retorting and to evaluate the extent of fragmentation by various methods. A combination of three methods of explosive fracturing was used: (1) The displacement and detonation of a liquid chemical explosive in a natural fracture system; (2) the use of 60-pct dynamite to relieve stress conditions of the rock around the wellbore; and (3) the use of pelletized TNT in a series of wellbore shots to fragment the oil shale. An attempt was made to seal or grout around the fragmented oil shale by drilling 67 holes and displacing approximately 200 bbl of neat cement in the fracture system to aid in evaluating the fragmented zone, Seven methods were used to evaluate the fragmented zone. The primary evaluation method was the recording of seismic waves to delineate the fragmented zone with results based on arrival time, amplitude, and record quality. The data from the seismic measurements indicated the extensively fragmented zone was approximately 95 ft in diameter and 70 ft thick. Results of the remaining methods of evaluating fractures--including air-flow tests, coring of the expected fragmented zone, elevation measurements to indicate overburden crowning, and surveys with high-speed camera, impression packer, and down-hole camera--agreed with and supported the data from seismic measurements. Further field application of explosive fracturing and evaluation methods is needed to determine when a zone of oil shale is effectively fragmented for efficient in situ retorting.

Jan 1, 1973

By E. J. Gleim

Contact with trolley wire in the mines of the United States has taken a considerable toll of life throughout the years that trolley locomotives have been employed as a means of' transportation. A study3/ of the records over a 15-year period for one State alone showed that, of 98 fatalities resulting from contacts with electrical circuits and equipment, 75 were caused by direct or indirect contact with unguarded trolley wire in coal mines. The law relating to guarding trolley wires in the mines of this particular State, as amended in 1935, reads in part as follows: "All trolley wires carrying 220 volts or more, and less than six feet six inches above top of rail, must be guarded at all points under which men and animals are required to pass***,'" The natural conclusion to be drawn from such records is that lack' of guards or shields must be held responsible for these fatalities. As a preventive measure, it has been advocated that every foot of trolley wire in mines should be guarded. Although some such drastic steps may appear to be amply justified, closer examination of the records nor this and other coal-mining States shows that absence of guards is not entirely responsible; but rather that other factors, such as carelessness and neglect it the observance of certain well-established simple rules concerning installation and location of trolley wires, also are responsible. In other words, if trolley wire is installed carelessly and its maintenance is neglected, it should not be expected that the mere installation of guards will overcome such carelessness and neglect. This publication discusses Various types of guards that have been used in Coal and metal mines of this country, together with related steps bearing upon the problem of 'preventing shock and fatalities from contacts with trolley wire. The material herein contained is taken largely from Information Circular 6577,4/ now out of print, and has been revised to include some types of guards that have been used in metal mines, together with a discussion of guard materials not covered in that publication.

Jan 1, 1945

By George H. Schnakenberg

Automation of coal mining activities at the face offers improvements in worker safety, health, and productivity. Introduction of integrated computer-sensor systems to current mining machines will enable these machines to perform some of the most hazardous tasks through supervised teleoperation. The U.S. Bureau of Mines is pursuing the development of the enabling technology necessary to achieve this goal. The research program consists of both basic and applied research, each focused on the fundamental issues of computer and sensor technologies. Short-term research is directed to providing computer-assisted, remote supervisory operation of present underground equipment; the long-term goal is the development of progressively more intelligent mining systems. The research program includes a review of robotic machine and autonomous vehicle technologies and of current mining technology, which provides a base for developing innovative mining methods; research in navigation and guidance technology, emphasizing control of a continuous mining machine; research on coal-rock interface sensing technology for horizon control, and rib thickness control in highwall mining; the development of computer systems and hierarchical architectures for real-time control; and development of expert systems for machine system fault diagnostics and predictive maintenance. This report presents a brief background and the current status for each of these research areas.

Jan 1, 1989

By H. H. Schrenk

There are several well-recognized procedures for controlling exposure to hazardous atmospheres in industry. They include (a) substitution of less toxic material, (b) enclosure of processes, (c) wet methods, (d) local exhaust, (e) general ventilation, and (f) use of respiratory protective devices. In addition to their employment as a control measure in occupational exposures, respiratory protective devices also are essential in emergencies that may arise from failure or improper use of other control equipment. Respiratory protective devices usually are employed to supplement other methods of control, as temporary expedients, or when other methods are not readily applicable or practicable. It seems reasonable to assume, however, that where respirators are used consideration has been given to the factors involved and that the devices can provide satisfactory protection if used properly. Their use should not be arrived at simply by a process of elimination of other methods that are more difficult to apply.

Jan 1, 1943

By Noel N. Moebs

The coal wants at the Westland Mine in southwestern Pennsylvania consist chiefly of elongated, sandstone-filled channels with slickensided basal contacts. Tentatively identified as washouts, these channels are about 1,000 feet long and 300 feet wide, are erratic in occurrence and trend, and are difficult to delineate from the customary core drilling pattern. Roof conditions are hazardous adjacent to the washout contact, but roof stability is generally unaffected greater than 30 feet away.

Jan 1, 1981

By J. J. Jakosky

"This report is the second of a series dealing with electrical methods of underground communication nd signalling, and is a discussion of some of the factors involved in -applying radio in mines.A previous report2 described the results obtained by the use of the ""T.P.S."" of ground-conduction method of signalling, and outlined in a general way the requirements for a practical mine communication apparatus.The popularity of radio, the development work on new apparatus, a desire to render humanitarian service to entombed miners, and an endeavor to find new uses and applications for radio stimulated many persons to attempt the application of radio to mine rescue purposes. A number of experiments on underground reception from surface broadcast stations have been conducted by different experimenters in various parts of the country and the widespread interest in the subject is shown by the fact that these tests have been con¬ducted in many States, The Bureau of Mines has received information regarding, underground tests in Illinois, Pennsylvania, Arizona, Utah, Idaho, Colorado, Michigan, Wyoming, Kentucky, New York, Connecticut, and in England, Germany, Italy, and Franc.From occasional press notices and illustrations in different papers it may appear that radio communication in mines and in tunnels being excavated is en established fact, and that the method is comparatively simple. As a matter of fact the reverse is the case."

Apr 1, 1924

By Francis X. Cannaday

The Bureau of Mines developed equipment to measure the sonic velocity of pulses transmitted through rock samples varying in size from laboratory specimens to mine pillars in place. Pulses are produced by electronically excited piezoelectric ceramic transducers. Special equipment components were developed by Bureau facilities; other components are commercially available. The technique permits a nondestructive, repetitive, stable, shaped pulse to be used in place of explosive caps or hammer blows. Longitudinal wave travel time measurements were taken on an oscilloscope screen; transverse wave measurements were taken under special field conditions. Results were consistently repeatable within the accuracy of the oscilloscopes utilized.

Jan 1, 1966

By Allen D. Look

Uninterrupted shaft operations are an important economic factor in mine operation, and good shaft support is an important aid in preventing accidents and interruptions. More permanent supports can cut the hazards, costs, and delay incident to replacement of conventional timbers, especially where subject to decay. Installation of prestressed, precast concrete shaft supports in 100 feet of shaft at the Banner mine, Lordsburg, N. Mex., nave a satisfactory permanent installation in a section of shaft that had given trouble with conventional timbering. Use of rock bolts supporting gunited wire netting around the rock walls of the shaft prevented sloughing. No attempt was made in this paper to arrive at comparative costs of installation of various types of support. However, it was indicated that use of a lighter weight aggregate would be desirable in further use if prestressed precast members as placed in the Banner mine.

Jan 1, 1957

By C. F. McCarroll

[Laboratory research and, control in the u?odnction an; utilization of petroleum and its product s have eqLmde& greatly during the past decade, rind much of the routine control and experimental equipment noirr requires the con-stant daily use of liquid nercury. In spite of this greater use, very little consideration has becn given to the hazard that might be occasioned by the toxic vapors of mercury unavoicl.a~l.p spilled or otherwise exposed to the atmosphere during the normcl 2rgced1u.e of ln30r~tor;~r operations. A sfmple visual exami~stion gf' sone of the laborztories reveals the prescnce of a considerable quantity of mercury in the craclcs of floors, on work tebles, ad on and mo7md eql~ipmeilt st.ads. Usually this yercurj ie contaminated with oily and dirt BO th~t it remint; in R finely divided state and a srnarl amount presents a relativell- lag? surface for evaporation. Since mercury shows meas~rable vo!-atility st a tempero.turc as lor^ 2s 8.5O F., mercury vapor will bo present in the atnosphere of anjr laboratory wbr.e mercury is exposed. promiscuously]

Jan 1, 1939

By L. D. Wyant

[A convenient method for the, analysis of oil-wax mixtures has bean developed in the petroleum laboratory of the Bureau of Mines. This method has been found useful in studying the characteristics of the products obtained in petroleum refineries during the manufacture of ?wax distillate?, "foots oil", ?intermediate wax", and commercial paraffin. In this method ac-to-au is used as a selective solvent.]

Jan 1, 1924

By A. D. Garman

This paper presents one of a series of digests of foreign mining legislation and court decisions which is being prepared in advance of a general report relative to the right of American citizens to explore for minerals and to own and operate mines in various foreign countries. This interpretation of the laws of Colombia has been prepared from the best available information in Washington, but is released subject to correction and amplification; if necessary, by the proper American diplomatic and consular officers to whom it is being referred through the courtesy of the Department of State. SYNOPSIS OF LAW Minerals in Colombia belong to the owner of the soil unless otherwise provided in the law. The following lands and deposits, however, are described as fiscal property of the State: Class 1. The public lands, mines, and salines which belong to the individual States (now Departments) prier to the adoption of the present constitution (1886).

Jan 1, 1929

By Frank C. Andreuzzi

The Federal Bureau of Mines conducted a demonstration project to reclaim 125 acres of abandoned strip-mined land in Lackawanna County, Pa., for public recreational, historical, and educational use as a park. The Bureau was involved in the development of the general site plan, and engineered and supervised the basic land rehabilitation. The park's Facilities include outdoor recreational activities, picnic grounds, children's play areas, primitive overnight camping, and winter sports. A major attraction is the Anthracite Museum constructed by the Pennsylvania Historical and Museum Commission The project may serve as a prototype for reclaiming existing and future surface-mined lands.

Jan 1, 1976

By John F. Wiggert

The first signal system used in the Homestake mine between the cagemen and hoisting engineers was a mechanical one. It consisted of small cables or jointed steel rods hung in the cage compartments and counterbalanced with weights or springs. These cables or rod strings were connected to the mechanically operated gongs at the engineers' positions by means of bell cranks and steel wires. At the various stations the bell lines were also fitted with bell cranks and connected levers, so that the cagemen could operate the bells from the stations when they were handling rock or other material and not riding on the cages. Such a system was inherited from the days before extensive electrical development. It served quite well for shallow shafts, but for depths of a thousand feet or more it was very slow and cumbersome. It required consider-able muscular effort to operate it quickly, because of the inertis of its great weight and also because of frictional resistance. The maintenance cost was quite high because of the many wearing parts.

Jan 1, 1937

By L. C. IlsLey

Investigations for safety of electrically operated mine equipment, safety lamps, and gas detectors are made at the Pittsburgh Experiment Station in accordance with published regulations termed "schedules." These schedules are revised from time to time, not only to keep in step with the progress of the industry, but also to permit much freedom of design as possible without lowering standards of safety. The following schedule covering electrical equipment, safety lamps, and gas detectors are now active: Schedule 2D. Explosion-Proof Mine Equipment. Requirements for Approval of of Storage-Battery Locomotives and Power Tucks, Junction Boxes, and Electric Motor-Driven Equipment.

Jan 1, 1939