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By Paul W. Jeran

Subsidence was monitored by the U.S. Bureau of Mines over the ends of longwall panels operating in the Pittsburgh, Kittanning, and No. 2 Gas Coalbeds of the northern Appalachian Coal Basin. The final subsidence over the finishing ends of three panels in the Pittsburgh Coalbed are compared with the subsidence measured over the rib at these panels. The characteristics of subsidence are different. At Mine A, data over the start of a longwall panel shows similar characteristics to the subsidence measured over the rib. Subsidence over the fmishing ends of panels in the Kittanning and No.2 Gas Coalbeds are also different from the subsidence over the rib. The use of a subsidence prediction model based on data gathered over the rib of a panel will not yield accurate results if it is applied to the finishing end of a longwall panel. Acceptable results may be obtained along the centerline over the starting end of a panel.

Jan 1, 1991

By G. L. Oldright, Virgil Miller

"ACKN0WLEDGMENTSThe data given in this paper were collected at the Bunker Hill smelter through the courtesy of Stanley A. Easton, the vice-president and general manager, Frank M. Smith, the smelter director, and with the assistance and cooperation of A. F. Beasley, the smelter superintendent, and his staff members.THE BLAST FURNACE AND PLANTThe general lay-out of the recently built (1917) Bunker Hill plant has been given in the technical press in articles that were cited in Report of Investigations 3088. In addition it may be noted that the description of an ideal smelter given by Riddell 5 a year later fits the Bunker Hill smelter very well, with some changes, such as the location of the stack, made necessary by topography. For purposes of this article on the blast furnace it may suffice to state that the plant is one of the ""side hill location"" type. The various successively lower benches may roughly be considered as made for (1) the stack, (2) Cottrells and bag houses, (3) Dwight and Lloyd sintering machines with the equipment or bins for handling or mixing the feed and storing the finished product, sinter, and (4) the blast furnace feed floor with a slightly rising gradient to the bottom of the bins for sinter, feed, and take. The lowest bench (5) might be considered that of the blast furnace tapping floor at which or at appropriately slightly lower elevations are located the units for softening, refining, and treating precious metals, and for casting and loading lead. A very careful study of grades was made in order to be able to handle the products easily. All units were left with at least one end open to permit expansion of the plant, it desired, and each unit was separated from the other, evidently so that the operators on one level would be annoyed as little as posssible with the products made on another."

Apr 1, 1931

By M. J. Ferrante

Low-temperature heat capacities and high-temperature enthalpies were determined calorimetrically for Na2Cr04, A reversible transition was found at 700° K with an isothermal heat of transition of 2,263 cal/mole. High-temperature X-ray diffraction analysis showed that the transition was a crystal change from the low-temperature orthorhombic form to the high-temperature hexagonal form. At 795° K the hexagonal form had the parameters a, = 5.691 and co = 7.478 A. Powder diffraction data for the high-temperature form are given and possible structures discussed. The melting point was determined to be 1,065° K with a heat of fusion of 5,810 cal/mole. Enthalpy and entropy increments from this investigation were combined with other data from the literature to calculate enthalpies of formation, free energies of formation, and equilibrium constants of formation from 298° to 1,400° K. Equations that represent enthalpies above 298° K are given.

Jan 1, 1972

By E. D. Gardner

About 300 tons of gold ore per week was being produced in February 1934 by Thomas D, Herron and Con Laster from the old lake Superior and Arizona workings; the ground was leased from the Magma Copper Co. The workings adjoined but were not a part of the Magma mine. The lessees had been employees of the Magma Copper Co, at the time the Magma closed down for the summer of 1932. Work on the lease began in July 1932 on an exposure of $2-per-ton ore disclosed in a drift; after a few hand-drilled rounds were blasted the gold content increased to about $30 per ton. Extensive sampling by pannings elsewhere of exposed portions of the vein indicated that other ore shoots existed. The last work previously done in the mine was during the World War, when lessees mined a number of small shoots of copper ore. In some of the stapes the copper miners had left a quartzose streak on the hanging wall that carried $15 per ton of gold. This material did not look as if it cried values and evidently never had been sampled. The first shipment of gold ore was made on September 28, 1932. Up to April 1, 1933, 3,778 tons had been shipped and from September 1, 1933, to January 31, 1934, 3,125 tons.

Jan 1, 1934

By Hon-Chung Ko

This Bureau of Mines report provides the enthalpies of formation of cupric bromide and cuprous bromide as determined by hydrochloric and hydro-bromic acid solution calorimetry. At 298.15 K, the values are -33.10 ± 0.4 kcal/mole for CuBr2, and -25.24 ± 0.25 kcal/mole for CuBr.

Jan 1, 1975

This is an audience, I know, that shares my interest in a subject that is currently getting a lot of attention -the tendency of our Nation to draw increasingly on overseas supplies of certain mineral commodities, and proportionately less on domestic sources for these minerals. That we do obtain substantial quantities of some essential minerals from abroad is easy to demonstrate. That we will continue to do so in the foreseeable future is not in doubt. Uncertainty begins, however, when we try to interpret the significance of these facts. As with many phenomena, their meaning is open to a variety of interpretations.

Jan 1, 1980

By David Gearhart, Thomas Barczak

Hydraulic cylinders a re used in several roof support systems, such as longwall shields and mobile roof supports, to provide critical ground control Many state-of-the-art hydraulic support systems operate at pressures as high as 7,000 psi to provide the necessary support capacities. Pressure in the upper stages of multi-stage cylinders can be intensified by a factor of 2 or 3 providing pressures of 20,000 psi or greater. A proper understanding of the operation of these high pressure systems is necessary to safely maintain and repair these support systems. Likewise, the performance characteristics need to be fully understood to evaluate the impact of design parameters on the capability of the support to maintain effective ground control. This paper examines the basic operating principles of state-of-the-art hydraulic cylinders and discusses relative issues pertaining to. (1) setting loads, (2) support stiffness, (3) yielding behavior, (4) errors in assessing support loading, and (S) hydraulic failure mechanisms and how to detect them

By L. C. IlsLey

The Burrell methane indicator developed by Col. G. A. Burrell in 1915 was modified during 1918 to the " insulated type " Burrell indicator . Though this instrument has been used in mines since its first introduction , it was not formally approved as safe and efficient for use in gaseous mines until March , 1922. The indicator is built by the Mine Safety Appliances Co. , Pittsburgh , Pa . Approval No. 800 has been assigned to this company covering the device in the form approved . The principle of the Burrell indicator is fairly well known . It works on the same principle as the Haldane apparatus - measuring by means of a graduated scale , the contraction resulting from burning the methane content of an air and gas sample . A given aniount of the mine atmosphere to be tested for methane is taken into the indicator . This sample is then thoroughly shaken with the water in the indicator for one minute . The methane in the sample is now burned for two minutes by a heated platinum coil , which is energized by a small storage battery containing two Edison cells connected in series . After the glower or coil has burned for two minutes , it is disconnected from the battery , and the indicator is again shaken for The amount of contraction observed by reading the height the water rises in the U- tube of the indicator , which is calibrated to register the percentage of gas in the sample . The indicator as approved by the Bureau of Mines is equipped with an Edison M- 8 mine- lamp battery , and with a glass and scale graduated from zerɔ tɔ four per cent methane . The approval of a corbination service that is , an attachment for giving illumination from the same battery from which the platinum glower is operated has been withheld pending the development of a battery with larger capacity . - Under laboratory operating conditions , a single glower was capable of making at least 20 determinations if proper precautions were observed with respect to the use of freshly charged batteries . A battery should be allowed to stand off charge several hours before using in an indicator , as the peak voltage of a freshly charged Edison cell is abnormally high and is likely to send enough current through the glower to melt the platinum wire . Fifty-seven satisfactory operations were obtained from a completely charged battery . The point where the voltage of the cell fell below 2.3 volts with the glower attached was taken as the lower limit of successful operation . A voltage less than 2.3 does not permit the lower to burn at a temperature that will completely burn the gas in the air , thus giving a false indication .

Jun 1, 1922

By E. D. Gardner

"A fire hazard exists in nearly all mines. Progressive mining companies recognize this danger and take all possible precautions to prevent any conflagrations, but in spite of such safety measures, mine fires do occasionally occur and endanger life and property. In order to be prepared for such an emergency, miners are trained in the use of self-contained breathing apparatus and the necessary fire-fighting equipment is kept on hand. Men trained to wear breathing apparatus can penetrate workings full of poisonous fumes, but in order to successfully combat fumes or to rescue miners, the rescue crews must be trained in fire-fighting operations and know how to proceed with a minimum loss of time when they get to the scene of action.In order to perfect fire-fighting plans and to train men of the Globe-Miami district under conditions approximating those found at an actual mine fire, mine-reseue maneuvers were held at Globe, Arizona, on October 17-20, inclusive. The work was done under the direction of Orr Woodburn, director, and his associates of the Globe-Miami District Mine Rescue and First Aid Association. He was assisted by Albert Tallon, safety engineer, and Herbert Finnegan of the Old Dominion Co.; Herbert Hodson, safety engineer for the Inspiration Consolidated Copper Co.; A. 3. Martinson and J. M. Harrington of Car One, and F. D. Gardner of the Southwest Station, Bureau of Mines. Invitations were issued to mining men likely to be interested and representatives of mining companies from other districts were present and observed the work.The Globe-Miami District Mine Rescue and First Aid Association is maintained by the mining companies in the district and each company contributes to the organization's support in proportion to the total number of men on the pay roll. A central station*, between Globe and Miami, has been established and a truck with 10 sets of 2-hour self-contained breathing apparatus and the necessary accessories is always in readiness to respond to a call to any of the mines in the district. Besides being in readiness for emergency work, the station employees train men in the use of mine-rescue apparatus and in first-aid to the injured at the mines of the association. The Globe-Miami Mine Rescue organization has been developed to high point of, efficiency under Mr. Woodburn's direction and is one of the best in the country. The three largest mines of the district such maintain a crew of 15 men trained in the use of breathing apparatus, and other mines keep crews of 5 men each."

May 1, 1923

By J. M. Stuve

Calorimetric data for the dissolution of scandium sesquioxide and scandium trichloride in 4.360 molal hydrochloric acid were used to evaluate the standard heat of formation of ScCl3(c). The heat of reaction for Sc(c) + 1.5Cl2(g) = ScCl3(c) at 298.15° K was computed as -225,440 ±340 cal/mole.

Jan 1, 1965

By Jon C. Volkwein

Dust concentrations inside and outside enclosed cabs on several types of mining machinery were measured by the Bureau of Mines. Results indicated that properly enclosed cabs can offer significant dust protection for machine operators. Recommendations for improvements in cab technologies were discussed.

Jan 1, 1979

By Charles T. Chislaghi

An economical, remotely operated (automated), temporary roof support (ATRS) has been developed by the Bureau of Mines for use on a single, fixed-head roof-bolting machine (squirmer) that operates in low coal seams (less than 42 in thick). The ATRS eliminates the need for squirmer operators and helpers to go under unsupported roof to set or remove temporary support prior to or during the roof-bolting cycle--a task that annually accounts for approximately 20 pct of all roof fall fatalities. The ATRS can be adapted to any squirmer used in the U.S. low coal fields. A prototype ATRS was field-tested at Imperial Colliery Co.?s Mine No. 20 in Eskdale, W. Va. The Mine No. 20 amended roof- control plan, which requires the use of the Bureau?s ATRS as temporary support during face bolting, has been approved by the Mine Safety and Health Administration (MSHA), U.S. Department of Labor.

Jan 1, 1982

By G. L. Oldright

This paper is the first of a series that is to appear on smelting in the lead blast furnace. The objects of this investigation are to determine the conditions obtaining within the blast furnace by direct experimentation, and to correlate the behavior of the furnace at various times with the main factors governing the operation of the blast furnace, and metallurgical losses. ACKNOWLEDGMENTS The writers wish to express their appreciation to the management of the International Smelting Co. at Tooele, Utah, to Mr. J. O. Elton, the general manager, and to Mr. A. B. Young, his assistant, for their broad-gauge policy that has made possible the securing and publishing of these data. For the staff at Tooele, acknowledgments are made to Messrs. B. L. Sackett, general superintendent, Carlos Bardwell, assistant general superintendent, S. Jacobsen, blast-furnace superintendent, H. M. Rockwell, assistant blast furnace superintendent, and J. O. Welsh, superintendent of the general research, for the spirit of cooperation they manifested in carrying out this work. Mr. C. Reish, a member of the research department, was detailed by, the company to assist in this' work and his whole-hearted assistance has been found invaluable.

Jan 1, 1929

Coal-bearing beds underlie 23,000 square miles, about one third of Missouri's total area. Twelve out of more than twenty named coal seams have been or are being commercially mined. The remainder are too thin for commercial production. The coal is high volatile bituminous, with reserves estimated to be six billion tons, 1.24percent of U.S. coal reserves. Coal-bearing strata are generally thin seams which can be up to five feet thick. Typically, mined seams are about 28 inches thick. Coal deposits were first mined in Missouri in the 1840s, with the coal used primarily for domestic heating and blacksmithing. Production increased with the introduction of steamboats on the Mississippi. Coal production in 19 17 was six million tons. Production has steadily declined from a high of nearly seven million tons in 1984 to 2.3 million tons in 1991. Declining production is the result of several factors, including competition from other energy sources and the high sulfur content of Missouri coal. Today, coal-fired electric generating plants are the biggest consumers of Missouri coal. The Missouri regulatory program was conditionally approved November 21,1980, and fully approved January 17,1983. Its Abandoned Mine Land program was approved January 29, 1982.

Jan 1, 1992

By S. L. Windes

"INTRODUCTION For a number of years the bureau of Mines has been engaged in the detection, recording and interpretation of earth- and air-transmitted disturbances, man-made and natural, related to mining operations. For the measure¬ment of such disturbances, special equipment was developed (1, 2, 3, 4, 8) 3/ and results of the measurements have been reported (5, 6; 7,9).In general, the ranges of amplitude end frequency of vibration encountered and recorded in the earth-transmitted disturbances were 0.00005 to 0.1 inch and 5 to 5,000 cycles per second; in the air-transmitted disturbances, pressures ranging from 0.001 to 100 pounds per square inch and 0 to 20,000 cycles per second were recorded.One characteristic of the earlier tests was that either the arrival time of the disturbance to be recorded was predictable or the recording speed was slow enough so that the record covered extended periods of time (for example, 4 hours). As the investigations continued, it became apparent that a recording device was required that would respond to transient vibrations arriving at indeterminate times and at the same time provide a permanent record of displacement or acceleration versus time on a scale that would permit the analysis of waves having frequency components up to 10,000 cycles per second. A film or paper speed of 720 inches per second was found to be adequate, as this provides approximately 3/4 inch of record for each 0.001 second."

Dec 1, 1947

By A. W. Khair, S. J. Jung

"A fundamental study of fragment size distribution and characteristics of fracture pattern is presented for the dynamic penetration of a conical bit into coal block. In this paper, damaged zones during crater formation and fragment size distribution were studied. Bit with a sharper tip angle and a smooth body configuration performed better penetration. Results suggest that in coal cutting the trend should be toward the face cleat direction using a sharper angled tip bits which consumes less energy for an optimum range of penetration depths, thus attaining maximum cutting efficiency and reducing fine fragments.1. INTRODUCTIONMuch research in the past has been done on energy requirements and mechanism of energy dissipation for ideal rock fragmentation in cutting process. However the mechanisms of energy dissipation or failure criteria for rocks in cutting process in order to evaluate the efficiency of energy requirements in specific rock fragmentation is not well understood. The formation of a crater in rock under the impact blow of a bit has been observed experimentally (Hartman, 1959). It is known that directly beneath the edge of the bit the rock is crushed into fine powder, toward the sides of the crater it chips out into relatively large fragments. (Sikarskie & Cheatham, 1973). Singh et al. (1967) investigated the cratering process under the two different conditions of static and dynamic loading. They found that the amount of energy consumed per unit volume of crater is unequal for the two different loading conditions. A complex network of fractures often extends downward and laterally into the rock below the bit. The surface of the specimens showed that the dynamic loading damaged larger area then the static loading."

Jan 1, 1989

By Miklos D. G. Salamon, Jim M. Galvin, Bruce K. Hebblewhite

A series of mine design accidents in the late 1980s resulted in a major research program at the University of New South Wales, Australia, aimed at developing pillar and mine design guidelines. A database of both failed and unfailed Australian underground coal mine pillar case studies was compiled. A procedure was developed to enable the effective width of rectangular pillars to be taken into account. The database was analyzed statistically using the maximum likelihood method, both independently and as a combined data set with the more extensive South African database. Probabilities of failure were correlated to factors of safety. It was found that there was less than a 4% variance in pillar design extraction ratios resulting from each of these approaches. There is a remarkable consistency between the design formulas developed from back-analysis of the two separate national pillar databases containing many different coal seams and geological environments.

Jan 5, 1999

By H. H. Schrenk

The Bureau of Mines midget impinger dust-sampling apparatus was described first in 1937.4/ Two supplementary reports5/6 were published in 1938. These reports are now out of print. The material published previously is combined in this paper to make information on this device available for distribution. The impinger was developed by the Bureau of Mines in cooperation with the United States Public Health Service in 1922. The underlying principle of this instruments is based on impingement land wetting, of the dust particles by drawing air through a nozzle at high velocity onto a smooth surface under a bubbling column of liquid. The dust particles are retained in the liquid. The apparatus has been used widely and permissible limits of dustiness have teen established in the United States on the basis of results obtained with this device in correlation with medical studies. However, it has been criticized for its bulk, weight, and power requirements.

Jan 1, 1939

By Blair Burwell

This paper describing the method of mining a deposit of vanadium ore near Rifle, Colo., is one of a series of similar papers on metal-mining methods and costs being issued by the United States Bureau of Mines. This vanadium deposit probably is the largest yet found in North America. It is situated 12 miles northeast of Rifle, Colo. (see fig. 1), on the southern flank of tae White River plateau, and is at an altitude of 6,500 feet. Between 150 and 200 tons of ore are mined daily and trucked to the mill at Rifle. The product of the mill is fined vanadium oxide, which is shipped to the company's plaits at Columbiana, Ohio, and Niagara Falls, N. Y., for the electric manufacture of ferrovanadium. HISTORY The deposit was discovered about 1909 by men prospecting for carnotite. Its outcrop on the bola cliff of Rifle Canon had been known to stockmen for many years.

Jan 1, 1932

By Dennis R. Dolinar

Screen material in the form of welded wire mesh and geogrids are used in underground coal mines to prevent the fall of small pieces of rock from the roof between roof bolts. Further, if the screen is installed during the production cycle, roof fall injuries can be reduced significantly. Therefore, the National Institute for Occupational Safety and Health (NIOSH), because of the safety implications, conducted an evaluation of screen materials commonly used in U.S. coal mines to determine their support characteristics and identify the parameters that could affect their performance with respect to controlling the fall of rock from the roof surface. To evaluate the load and stiffness characteristics of the screen, a test frame was designed and installed in the Mine Roof Simulator (MRS) at the NIOSH Pittsburgh Research Laboratory (PRL). With this test set up, the screen is bolted at four corners of the frame and a center load is applied. The test set up allows for up to 20 in of screen deflection while the load and screen defection are continuously recorded. A series of tests were conducted to evaluate the effects of various parameters such as bolt tension, the type of load bearing surface and the size of bearing plates on welded screen performance. The most common screen material used in U. S. coal mines is an 8-gauge wire welded in a 4-by-4-in spacing or aperture. The peak screen load was normally limited by wire breakage. The conditions at the bearing plate influence the nature of the wire breakage. However, the screen stiffness was controlled by slippage at the bearing plates, and by weld and wire failure. The size of the bearing plate had a significant effect on the performance of the welded screen. Therefore, the design capacity of the 8-gauge screen is evaluated based on plate size. For a 6-by-6-in bearing plate the average peak load is 2,900 lb with a stiffness of 250 lb/in. For an 8-by-8-in bearing plate, the average peak load is 4,500 lb with a stiffness of 430 lb/in. These test results are based on a 4-by-4-ft bolt spacing. A geogrid mesh was also tested.