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By Gregory Molinda

NIOSH has recently completed a study of the interaction between polyurethane (PUR) and coal mine roof in order to determine the mechanism of reinforcement, in both highly fractured rock and unfractured rock. Four case studies of PUR rein­forcement are presented. At a West Virginia site, a borehole camera revealed the location of roof voids and guided the PUR injection. By injecting polyure­thane into a zone from 0.6 to 1.8 m (2?6 ft.) high in the roof, a roof beam was created and ongoing intersection falls were halted. In another highly fractured roof in a western Pennsylvania mine, a total of 5.8 cm (2.3 in.) of rubbleized rock was found in a zone up to 3 m (10 ft.) into the roof. Untargeted PUR injection filled approximately 1/2 of the fractures. These two case studies showed that it is not necessary to fill up 100% of the void space to create stability. In the other two field sites, polyurethane was injected into weak, but unfractured roof. Post-injec­tion video monitoring showed that weak bedding planes were hydraulically wedged open and polyure­thane injected along bedding. The reinforcement value of this injection method is limited because of the wafer-thin layer of PUR introduced along bedding, and the lack of a PUR ??webbing?? which would serve as a structural framework to provide strength. It was determined that video inspection prior to PUR injection can aid in identifying the fracture zones to target, and minimize ??blind?? pumping and loss of PUR.

Jan 1, 2008

By Robert J. Anderson

"Introductory Statement:In melting the nonferrous metals and alloys for foundry and rolling-mill work, even with the best practice, there is always a loss, due principally to oxidation. Melting losses are a serious source of financial loss in brass and bronze practice, but they are especially serious in the case of aluminum and its light alloys because of the relatively high price of aluminum. The indications are that the melting losses in many aluminum foundries of the United States are at times high, and in some plants (especially where certain furnaces are used) they are entirely too high when compared with the average practice. The fact that the oxidation losses in melting aluminum and its light alloys are high is well known, but it is doubtful whether the factors governing the most suitable methods of melting for a minimum of dross are equally well known. The metal losses involved in melting are worthy of especial attention now because of the rapidly growing importance of the aluminum industry.Factors in the operation of furnaces which affect metal and fuel losses:The essential requirements in the commercial melting of any metal or alloy are that the melting losses should be low, the melting should be rapid, and the melting cost should be low. Certainly it may not be possible to obtain these requirements in any furnace selected at random, and it follows that the design and the operation of furnaces for melting different metals are subjects that warrant the most extensive study and tests. As a general rule, in the industrial operation of furnaces, run on aluminum and aluminum alloys, an effort is made to keep the dross and oxidation losses as low as possible. In attempting to hold dross losses low, numerous factors involved in metal melting may be overlooked, or at least disregarded, and the net practical result may be that the furnace is exceedingly wasteful of fuel. In the case of aluminum and its light alloys, the effect of increasing the temperature of melting, at least in an atmosphere containing free oxygen and nitrogen, is to increase the net melting loss."

Apr 1, 1921

By Don Belsher

Work on contract H0272007 is summarized for the period of 1 February 977 to 1 February 1978. The initial evaluation of two potential systems for the location of well casings, voids, and tunnels in coal are described. The pulse measurement equipment used for the evaluation of the antennas selected possible use with a pulse time domain system and an FM-CW system is described. A TEM horn antenna design potentially suitable for use with these systems is given. An operational comparative analysis between various antenna types is presented.

Jan 1, 1978

By Oliver Bowles

The National Granite Commission at its annual meeting in Norfolk, Va., in January, 1930, passed a resolution requesting the Bureau of Mines to conduct an economic study of the granite industry. In compliance with this request a preliminary review has been made of trends, in, the production and uses of block granite. Some unfavorable conditions, were, thus brought to light and certain suggestions regarding a. more orderly and consistent growth in the industry are herein discussed. The results of the study axe, presented in this report for the earnest consideration of the industry and comments are invited, not only on this report but as to future work that might be accomplished by the Bureau of Mines. The authors desire to acknowledge many helpful suggestions and comments from Paul M. Tyler of the Bureau of twines and from Harris F. Sherman, secretary of the National Building Granite Quarries Association. Miss A. T. Coons of the Bureau of Mines rendered valuable, assistance through her wide knowledge of granite statistics.

Jan 1, 1931

By William S. Miska

The study is an economic evaluation of historical, current, and projected refractory uses in the iron and steel industry of the United States. The first part of the report presents a refractories classification and identifies principal trends in the refractories industry; such as, value and volume of shipments, prices of finished refractory products, the number of manufacturers and plants for refractories production and marketing. The main part of the report treats refractory use patterns and technologic developments affecting refractories usage in the iron and steel industry. Changes in use patterns in each furnace type, refractory, and installation costs and the future outlook for refractories in ironrnaking and steelmaking are covered. The last part of the report identifies the principal raw materials used in refractories production and treats trends in refractory raw material consumption. An appendix to the report contains historical time series graphs of shipments of refractory types used primarily by the iron and steel industry and principal refractory raw materials sold or used by producers. An equation of the line of best fit was calculated from the earliest to the latest year in each time series, usually 1950 to 1965; these were extrapolated in order to derive volume estimates for the year 1975.

Jan 1, 1968

By Bolmerm R. L.

This information circular describes the application of modern methods and equipment in sinking a vertical, 916-foot-deep by 16-foot-diameter, concrete-lined access shaft for the Harold D. Roberts tunnel near Montezuma, Colo. Although the access shaft was merely a construction facility to expedite completion of a 23-mile water-diversion tunnel, a circular shaft of this type would be equally adaptable for mine development or other purposes. Comparable sinking methods and equipment could be used for similar shafts within a wide range of sizes and depths. SUMMARY In addition to excavation and support of the basic access shaft to tunnel grade, the overall sinking project involved initial preparation of a surface site and plant, subsequent construction of a tunnel-level station and loading pocket at the shaft bottom, and ultimate conversion of the basic shaft into a hoisting and access facility for tunnel operations. The sinking period for the basic shaft approximated one year. Actual tunnel operations through the converted shaft began on April 3, 1958, approximately 19 months after the project was initiated.

Jan 1, 1961

By H. N. Dunning

A comprehensive research program designed to aid development of new and improved methods for more complete production of petroleum from partly depleted reservoirs is being conducted at the Bureau of Mines Petroleum Experiment Station, Bartlesville, Okla. Water flooding has accounted for much of the petroleum produced by secondary-recovery methods; however, a considerable portion of the crude oil commonly remains in place after water flooding has been terminated. In recent years the possibility of increasing the efficiency of water flooding by using surface-active additives has received wide attention. In general, the results of laboratory research have shown that use of detergents as water-flooding additives will reduce the residual petroleum in porous media (1).3/ Some less extensive field tests have supported this conclusion but have not been entirely conclusive (2). Later studies (3, 4) have given conflicting evidence as to the relative worth of detergent additives for water floods in water-wet (hydrophilic) or oil-wet (hydrophobic or lipophilic) reservoir materials. The results of these studies emphasize the need for a more complete understanding of the fundamental principles involved in displacing petroleum from reservoir surfaces by injected fluids. Accordingly, a comprehensive research program was initiated to investigate the practical and fundamental aspects of detergency in petroleum production.

Jan 1, 1953

By Leonard F. Heising

At the Groveland-mine iron ore is mined by open-pit methods and concentrated by means of spirals and flotation. A brief history of the mine and its early development is given. The ore deposit is described, with emphasis on those physical characteristics that affect the choice of mining and milling methods. Development and mining, which include breaking ground, loading, transportation, engineering, and operating control; are explained, and the milling method is described Mining and milling costs are given in percent of total cost.

Jan 1, 1963

By L. D. Tracy

This paper represents work conducted by the Bureau of Mines in cooperation with the Illinois Geological Survey and the Engineering Experiment Station of the University of Illinois.

Jan 1, 1926

By Kara A. Teacoach

Current regulations for fire suppression systems in underground coal mines to protect conveyor belt installations have been in place since the Coal Mine Health and Safety Act of 1969 was enacted. Over time, the coal conveyer equipment being used and ventilation conditions underground have changed significantly, particularly the width of the conveyor belts and the use of belt air at the face. The effect of these new conditions on the effectiveness of suppression systems during a fire is not known. The National Institute of Occupational Safety and Health (NIOSH) conducted a study to evaluate the effect of air velocity, water sprinkler activation temperature, and a limited water application time on the effectiveness of water sprinkler fire suppression systems to extinguish large-scale conveyor belt fires. The fire tests were conducted using both new and used 1.8-m-wide, fire-resistant rubber belt that met the Mine Safety and Health Administration (MSHA) flame resistant requirement specified in Title 30, Code of Federal Regulations, part 18, section 18.65 (also known as the 2G test). Tests were conducted using standard response sprinklers with activation temperatures of 68 °C and 141 °C at air velocities of 0.5 and 5.1 m/s. Two tests were conducted at both air velocities for each sprinkler activation temperature, one using a new belt and one with a used belt. The results showed that the suppression system was able to suppress the fires in ten minutes to the point that a miner could extinguish it with a fire hose. However, in several of the tests, the fire reestablished itself a few minutes after the sprinkler water supply was cut off and quickly grew out of control. This report discusses the large scale experimental configuration, the installation specifications of the fire suppression system, and the results and conclusions regarding the effect of air velocity, sprinkler activation temperature, and limited water application on the suppression system performance.

Jan 1, 2010

By W. W. Weller

Thermodynamic values for scandium and its compounds are very sparse. This is evident upon examination of any of the commonly used compilations of thermodynamic data. For example, National Bureau of Standards Circular 5004 lists only four heat of formation values, two free energy of formation values, and four heat-capacity values for scandium compounds. The entropy of crystalline scandium is one of the most fundamental values that has been lacking. This Bureau of Mines paper reports heat-capacity data for scandium metal in the temperature range from 50° to 298° K., together with the entropy value at 298.15° K. derived from these data through application of the third law of thermodynamics.

Jan 1, 1962

By R. Ward Stahl

This publication is a revision of Report of Investigations 5363 updated to reflect the improvement in fire protection at selected coal mines and contains suggestions on what may be considered good fire protective equipment, suggested methods of organizing the attack on fires at various locations underground, and helpful hints on testing and evaluating firefighting facilities.

Jan 1, 1968

By C. M. Harrer

The location, features, qualities, and extent of iron occurrences and the associated resources--limestone and dolomite, bentonite, coal-lignite, petroleum and natural gas, power, and water--are evaluated. The results of pioneer beneficiation tests on South Dakota taconite are discussed. In addition, pertinent features of taconite development, cost factors, the Western and Central United States trade area and markets are reported. The State's production of iron ores until 1963 has been small and for purposes other than the manufacture of iron. This investigation disclosed the probability of large resources of taconite in Pennington and Lawrence Counties. The average iron content is 29 percent, and a 65-percent or better iron concentrate might be produced. Ample resources are available for mining and processing taconite. An investment of at least $26 million would be required for a plant capable of turning out 1 million tons of agglomerated iron concentrate per year. The feasibility of such an enterprise is indicated, but intensive investigation and research must be completed to justify such an investment.

Jan 1, 1966

By Y. Miron

'This report presents a U.S. Bureau of Mines study to identify the causes of self-heating events beneath the floor of a deep underground coal mine. Mine samples from both heated and unheated areas were examined by various techniques, including visual, microscopic, thermal, chemical, and instrumental tests. The combined results led to the conclusion that pyrite (FeS2) oxidation was the prime cause of the beatings. However, adiabatic oven tests of selected samples did not indicate the effect of the pyrite on the self-heating process, probably because of the experimental conditions. A fast, simple procedure to assess the concentration of pyrite in the mine samples was developed, g the reactivity of the sample with an aqueous solution of hydrogen peroxide (H2O2).

Jan 1, 2010

By Robert H. Merrill

This report summarizes the first phase of studies to determine the design and behavior of an unsupported roof in an experimental room in limestone. The selection of a roof horizon and the design of the room were results of an investigation of the geology of the formation, the physical properties of samples from the proposed roof, and calculations from the theory of gravity-loaded beams. The design of the opening, some physical properties of the roof in place, and the behavior of the roof were checked by tests in a full-scale experimental room. The room was instrumented to measure roof deflection, separations in the roof strata, and incipient failure. The dimensions of the room before instrumentation was installed were 10 by 100 feet; the room was widened in successive increments to 40 by 100 feet. Between widening operations periods up to 6 months were allowed to provide a time test of the roof spans. The results of the measurements of deflection and separations showed that the lowest 6-inch layer in the roof became detached as the room was widened. This layer was eventually removed after standing without failure for about 4 months at room dimensions of 40 by 100 feet.

Jan 1, 1957

By Richard L. D?Arcy

This paper describing the mining practice and methods at the United Verde Extension mine, Jerome, Ariz., is one of a series of papers in preparation by the Bureau of Mines presenting the mining methods used in various mining districts of the United States. The United Verde Extension mine is a massive, high-grade deposit of copper sulphide containing some gold and silver and is mined almost exclusively by the conventional square-set method with some local modifications. About 450 men are employed underground and 1200 tons of direct smelting ore is produced per day. Figure 1 is a surface map of the Jerome district.

Jan 1, 1930

Construction workers may be exposed to hazardous dust containing silica when working in enclosed cabs during construction activities. The National Institute for Occupational Safety and Health (NIOSH) found that equipment operator exposure could be reduced by retrofitting air pressurization and filtration systems on existing cabs, using sweeping compounds on soiled floors, and implementing a dust control program.

Jan 1, 2009

By Robert L. Lappi

This report covers the final phase of a project demonstrating the economic efficiency of cross-ridge mountaintop coal mining. A demonstration mine was established at Big Wheel Gap in northeastern Tennessee. Not only was cross-ridge mining feasible for the selected site, but parallel cut methods could not be used due to a deficit in available spoil storage. Cross-ridge mining permitted coal extraction at a cost almost identical with costs simulated by computer projections using mathematical optimization techniques. No unexpected environmental problems were encountered. Volume I is accompanied by Volume II which describes the MATHMINE Mine Simulation System, software used to support the mining demonstration.

Jan 1, 1984

By R. A. Beall, W. E. Anable

The purification of hafnium by electron- beam melting at moderate energy inputs and at low pressures was examined in detail . Most metallic impurities and hydrogen were removed in the first few minutes of operation ; oxygen , carbon , and nitrogen were removed at a slower rate . Samples treated by electron bombardment suffered a small loss of weight and a gradual lowering of hardness . The magnitude of each change varied with the energy input and the duration of the melt . Analysis of the data confirms the loss of oxygen as a hafnium monoxide . Approximate activity coefficients for other contaminants are given .

Jan 1, 1964

By J. Alton Burks

When acoustical materials are used in a mining environment for noise control purposes, they are subject to environmental deterioration from hydraulic fluid, moisture, and dust. These and other factors can cause physical degradation of the material, which can lessen its ability to absorb sound. In this study, the Bureau of Mines measured the sound absorption properties of 16 different acoustical materials after 4 sample treatments: (1) being kept clean and dry (as received from the supplier), as a control or reference standard, (2) immersion in water and draining, (3) immersion in lOO-pct-petroleum-type hydraulic fluid and draining, and (4) exposure in a coal mine. The last three treatments were used to approximate the type of physical degradation that can be experienced in actual use. The impedance tube or standing wave method was used to measure the normal absorption coefficient. It was found that the absorption coefficient of most materials was adversely affected by the retention of either oil or water, with oil having the greater effect. The only class of materials that was affected by neither oil nor water was neoprene foam.

Jan 1, 1990