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By A. V. Hooker, E. J. Coggeshall

"The Bureau of Mines for some time advocated the firing of all blasts in coal mines as single shots, and this method of firing is the general practice in American bituminous-coal mines. All single shots can be fired with permissible single-shot units so designed that they will not ignite mixtures of methane and air.If several shots in a face are fired singly it is necessary to return the face after each shot. In some mines having steeply pitching coal seams, this may be dangerous or even impossible, under these conditions shots are usually fired simultaneously.Several shots cannot be fixed simultaneously with permissible single-shot blasting units, and safe types of multiple shots blasters are not readily available. This means that the firing of multiple shots in gassy mines is usually accompanied by the possibility of gas ignition as the blast occurs.Tests have been made at the Pittsburgh Experiment Station to determine the possibility of developing safe types of multiple-shot units suitable for such use, or of applying other type safely in gassy sections of mines where firing shots singly is impracticable.The tests may be divided into the following four groups:1. Tests to demonstrate hazard in the use of existing types of multiple-shot units of the portable generator type.2. Tests to show the electrical characteristics of multiple-shot generator units relative to the possibility of preventing igniting sparks and of modifying the design and application of such units in furthering safety."

Mar 1, 1935

By R. H. Sprute

Underground accumulations of slimes in the Henderson mine are routed to two large collection pits where they are dewatered and consolidated by application of direct current. Densified material is then removed to ore cars by rubber-tired front-end loaders and transported out of the mine. This Bureau of Mines report describes the electrical dewatering installation and compares its efficiency of operation with that predicted from preliminary laboratory studies performed by the Bureau. Direct current from a 150-kw rectifier (applied for 44 hours at 400 amperes and 65 to 70 volts) converted slimes containing 25.3 percent solids to material ranging from 44 to 65 percent solids. Better results can be expected if the ramp and front sections of the pits are treated separately, using higher current density.

Jan 1, 1980

By Gary P. Sames

Shale roof deterioration in coal mines. caused by ventilation air humidity fluctuations, is a common ground control problem. Shale roof deterioration often results in increased accidents, decreased production, inadequate ventilation, and increasing operating costs in maintaining haulage roads and airways. The results of Bureau of Mines research indicate that air tempering entries are an effective method of controlling deterioration prone shales. Some of the conclusions and recommendations drawn from Bureau research include (1) moisture sensitive shales will react adversely to moisture gains and losses, (2) the majority effect of specific humidity fluctuations can be concentrated in and absorbed by tempering entries, (3) tempering entry panels should be located as near to the main intake as possible, (4) tempering panels should be designed for a conservative recovery and provide a minimum of 20-to 30-min air residence time, (5) ventilation and escapeway requirements must be considered early in panel design, and (6) an efficient support and sealant plan can increase the life expectancy of a tempering panel.

Jan 1, 1985

By Richard L. Rains

The Bureau of Mines conducted a mineral investigation of the 29,000-acre Dixie Summit area near Elk City, Idaho, during the summer of 1989. At the Petsite mine a marginally economic, identified resource of 4.9 million tons with an average grade of 0.023 ounces gold per ton was delineated. Possible resources of gold, along with silver, copper, lead, and zinc, occur in at least eight other lode deposits. Placer gold may be recoverable by recreational-sized suction dredges in some stream drainages, Five lode mines in the study area have produced over 5,516 ounces of gold (placer gold production was not recorded), 4,757 troy ounces of sliver, 36,746 pounds of lead, and 3,800 pounds of copper. Current mining claims in or adjacent to the study area total 460 lode and 70 placer claims. There are two patented lode claims within the Dixie Summit study area.

Jan 1, 1991

By Philip C. Good

Unweathered low-grade calcareous phosphate rock of about 20 percent P205 grade was beneficiated by a procedure in which contained carbonates were decomposed by calcination at about 1,000° C. On quenching the hot calcined rock in water, major impurities passed into a slime phase which was mechanically separated from a coarser concentrate fraction. Phosphate rock of two major types was beneficiated in batch-scale studies yielding concentrates containing 31.3 to 38.5 percent P205 at recoveries ranging from 54.8 to 86.0 percent. The samples were from two major deposits in India. Processing information gained was utilized in extending the work to a continuous-flow system, processing phosphate rock at rates up to 157 kilograms per hour. Superphosphate exceeding 16 percent water-soluble P205 was prepared from concentrate derived from continuous-flow processing.

Jan 1, 1976

By L. B. Pankratz

Present-day interest in the rare-earth elements and their compounds, for both metallurgical and ceramic uses, makes it highly desirable to accumulate basic thermodynamic data that can be applied to theoretical considerations of the processing of these substances. Such data still are seriously lacking. This Bureau of Mines paper reports the results of high-temperature heat content measurements of the sesquioxides of four rare-earth elements--europium, gadolinium, neodymium, and samarium--and of the closely related element, yttrium. The temperature ranges covered by the measurements are as follows: Monoclinic Eu2O3, 298°-1,802° K. Cubic Eu203, 298°-1,350° K. Monoclinic Gd203, 298-1,802° K. Cubic Gd203, 298°-1,550° K. Hexagonal Nd203, 298°-1,795° K. Monoclinic Sm203 298°-1,798° K. Cubic Sm203, 298°-1,149° K. Cubic Y203, 298°-1,799° K.

Jan 1, 1962

By David R. Flinn

This Bureau of Mines report describes methods to electrodeposit erosion-resistant titanium diboride coatings from molten alkali metal borate baths at 900° C. These coatings have been shown to be highly resistant to material loss during impingement with high-velocity alumina and silicon carbide powders, and they show promise as protective coatings to reduce metal loss in erosive chemical environments, such as coal gasification systems. The most erosion-resistant coatings were prepared on nickel, Inconel, and molybdenum from an electrolyte containing LiBO2, NaBO2, Na2Ti03, and TiO2. The best coatings were deposited at current densities of [~]20 ma/cm2, using titanium or titanium diboride anodes. Erosion-resistant coatings were shown to exhibit (1) a high degree of crystallographic orientation along the (100) or (110) planes, (2) a chromium impurity level of less than 3 pct, and (3) a uniform, smooth, consolidated surface appearance when viewed under a microscope or by scanning electron microscopy. Optical spectroscopic studies of the molten electrolyte suggest that the lower valent (+3) titanium ion predominates in the baths.

Jan 1, 1979

By McHenry Mosier

This paper is one of a series recently undertaken by the Mining Branch of the Bureau of Mines to describe current practice in diamond drilling for production at various mines throughout the United States and to discuss the relative merits of this method compared with drilling by percussion rock drills . The Bureau of Mines and the mining companies that are cooperating with it in this ' investigation have the objective of developing information on diamond -drilling blast holes for the benefit of all who are interested in the possible improvement of mining operations .

May 1, 1947

By H. B. Humphrey, F. E. Cash

From 1900 to 1929 , 1,005 or approximately 30 per cent of all fatalities in the coal mines of Alabama were caused by fires or explosions of gas and dust . In the 3 -year period from 1927 to 1929 only 15 men were killed by these causes , a reduction from 30 to 9 per cent of the total . Notwithstanding this marked improvement , which is due largely to the efforts made by the State inspection department , the operators , and the Bureau of Mines to stamp out this type of disaster , Alabama still has more than its share of such fatalities which can and should be prevented. A list of explosions from 1894 to 1929 compiled from information obtained through the records of the State Inspector's office , the reports of Engineers of the Bureau of Mines , and the operators , is given in Table

Oct 1, 1930

A knowledge of the mechanics of wave propagation through the earth is essential if reliable communication systems are to be designed for coal mine environments. To obtain a reliable basis from which accurate propagation predictions could be drawn, a series of theoretical studies have been prepared for the US Bureau of Mines by Mr. Ramsay Decker of Spectra Associates, Inc. through a subcontract with Collins Radio Group. These reports formulate the analytical techniques from which we may derive frequencies and antenna configurations that yield the optimum signal-to-noise ratios over the greatest distances in mine environments. The reports of sections 2 and 4 deal with analytical techniques for determining the signal-to- noise ratio within a mine environment for loop-to-loop and line source-to-loop antenna con- figurations. The analytical results of these reports were then implemented into computer programs to obtain predictions concerning through-the-earth signal propagation. These preliminary predictions are based on noise data compiled by Bensema, Maxwell and Stone, and WVU prior to the extensive research conducted by the National Bureau of Standards (NBS). These initial measurements indicated a 20- to 30-dB lower noise level than that measured recently by NBS. The recent NBS data is that used by Collins in the final predictions. The following outline indicates the order and subject matter treated in the subsequent sections: Section 2 - Signal-to-Noise Analysis for Loop-to-Loop Mine Communications Section 3 - The Horizontal Electric Dipole Section 4 - Signal-to-Noise Analysis for Down-Link Line Source Mine Communications Section 5 - LF Communication Section 6 - The Application of Recent NBS Noise Data to Mine Communications Section 7 - Analysis of Mine Communication Propagation Programs

Nov 15, 1974

By William B. Harper

Domestic sales of carbon black sustained the upward movement for the 4th consecutive year, reflecting the increased sales of motor vehicles during the same period. Sales of carbon black in the domestic market topped 2 billion pounds for the first time during 1965 and have more than doubled the output of 20 years earlier. By far the largest user of carbon black is the rubber industry. That use accounted for more than 94 percent of the carbon black consumption with the bulk of it being used in tire casings and tubes. Thus demand for carbon black is naturally sensitive to trends in the sales of passenger cars and other motor vehicles, Manufacturers of inks, paints, plastics, paper chemicals, and food are also important users of carbon black.

Jan 1, 1967

By Jalna R. Zatko

Coal-clay waste slurries were dewatered in laboratory-and small-scale continuous tests by the Bureau of Mines using polyethylene oxide (PEO) as a flocculant. Dewatering from a nominal 7-wt-pct solids to over 50-wt-pct solids was accomplished using 0.5 lb of PEO per ton of feed in small-scale continuous tests. Parameters such as pH, initial solids content, and PEO concentrations were investigated. Water recovered from dewatering was reused as dilutant for PEO solutions.

Jan 1, 1982

By L. W. Scott, T. H. Dubaniewicz, F. T. Duda, P. G. Kovalchik

Recent research conducted by NIOSH, Pittsburgh Research Laboratory showed that electrical current levels permitted under parent regulations may not limit cable temperatures to less than 90 °C in reeled trailing cables. Reeled cables, tightly wrapped with many turns, ell carrying current in an enclosed space, can become overheated due to poor heat transfer. This overheating can cause the cable insulation to soften and become easily damaged. The damaged insulation reduces the life of the cable and can lead to shock, electrocution, and mine foes. This paper describes a method of measuring the conductor temperature of untie trailing cables during no anal operation. The temperature is measured using a 50/175 micrometer Graded Index Multimode Optical Fiber located in the center of the metallic conductors. Distributed temperature measurements arc made using an Optical Time Domain Reflectometer (OTDR). This system is capable of measuring temperature with an accuracy of plus or minus one degree centigrade over a length of 4 km at 1-m intervals. With this unique way of measuring temperature, tests can be conducted simulating actual mine conditions and provide important data to allow MSHA's Approval and Certification Center to develop approval criteria for cyclically rated reeled machines.

By C. H. Herty

Manufacturers and consumers of steel have come to realize during the past few years that cleanliness is of great importance in steels which must meet rigid specifications for various physical properties. Of equal importance is the consistent production of steel which is uniform in these properties. For maximum utility, steels should be uniform not only from heat to heat, but also from ingot to ingot and within each ingot. In the manufacture of killed steels such as the higher carbon forging grades, uniformity as indicated by the usual chemical analysis is easy to obtain, provided that a normal top discard is taken, as is al¬ways the case in steels poured with hot-top practice. No such uniformity, however, holds true for the nonmetallic matter, which consists for the most part of the products of deoxidation of the steel. For a large tonnage of steels which go into articles manufactured by deep-drawing processes, killed steel has never been successfully applied because with the present deoxida¬tion practice, low-carbon killed steel is almost invariably extremely dirty. To obtain the desired qualities for deep drawing, the steel is rimmed, - that is to say, deoxidized with manganese and perhaps a small amount of aluminum, - the resultant product being of high purity in the skin of the ingot, but very badly segregated at the center of the ingot, particularly in the upper-central section. This segregation necessitates a very heavy top discard, and one of the major segregates is carbon which renders the steel too hard to draw properly. If clean, low-carbon killed steel could be made successfully, much better ingot yields would be obtained than by the present rimming steel practice. Furthermore, banded structures and outside and inside seams, which are undoubtedly due in a large measure to blowholes in the ingot, are defects which are very difficult to control in rimmed steel. These defects would be minimized by clean killed steel.

Jan 1, 1931

By Jr. Herty

Manufacturers and consumers of steel have come to realize during the past few years that cleanliness is of great importance in steels which must meet rigid specifications for various physical properties. Of equal importance is the consistent production of steel which is uniform in these properties. For maximum utility, steels should be uniform not only from heat to heat, but also from ingot to ingot and within each ingot. In the manufacture of killed steels such as the higher carbon forging grades, uniformity as indicated by the usual chemical analysis is easy to obtain, provided that a normal top discard is taken, as is always the case in steels poured with hot-top practice. No such uniformity, however, holds true for the nonmetallic matter, which consists for the most part of the products of deoxidation of the steel. For a large tonnage of steels which go into articles manufactured by deep-drawing processes, killed steel has never been successfully applied because with the present deoxidation practice, low-carbon killed steel is almost invariably extremely dirty. To obtain the desired qualities for deep drawing, the steel is rimmed, - that is to say, deoxidized with manganese and perhaps a small amount of aluminum, - the resultant product being of high purity in the skin of the ingot, but very badly segregated at the center of the ingot, particularly in the upper-central section. This segregation necessitates a very heavy top discard, and one of the major segregates is carbon which renders the steel too hard to draw properly. If clean, low-carbon killed steel could be made successfully, much better ingot yields would be obtained than by the present rimming steel practice. Furthermore, banded structures and outside and inside seams, which are undoubtedly due in a large measure to blowholes in the ingot, are defects which are very difficult to control in rimmed steel.

Jan 1, 1931

By A. G. Smelley

As part of research conducted in its mission to effect pollution abatement, the Bureau of Mines, U. S. Department of the Interior, is developing a dewatering technique that allows for disposal of phosphatic clay wastes, for reuse of water now lost with clays, and for reclamation of mined land. The technique utilizes a high-molecular-weightnonionic polyethylene oxide polymer (PEO) that has the ability to flocculate and dewater phosphatic clay wastes. A synergistic flocculation study was made to determine whether a portion of PEO could be replaced by other reagents. Several groups of reagents were tested: (1) those that increased the zeta potential of the phosphatic clay wastes; (2) those capable of hydrogen bonding; and (3) those which flocculated the phosphatic clay waste. Reduction in PEO consumption occurred only with addition of those reagents able to flocculate the slime. The use of natural guar gums resulted in a lower PEO requirement and also yielded a dewatered product of higher solids content, 43 to 45 percent, versus 33 to 35 percent obtained with PEO alone.

Jan 1, 1980

By T. T. Read, T. L. Joseph, F. H. Royster

In a preliminary study of the beneficiation of iron ores conducted by the Bureau of Mines, one of the authors (T. T. Read) found it necessary to ascertain, if possible, how much effect a decrease in the silica content of an iron ore has upon the cost of making pig iron from the ore. In the beneficiation of iron ores the most important impurity to be removed is usually silica, and the amount that can be expended on a beneficiation process to reduce the silica content of the ore is obviously determined by the amount of increase in the value of the ore after beneficiation. The price that can actually be obtained for a beneficiated ore is, of course, a matter of negotiation between the seller and the buyer, but since the relative value of different grades of iron ore must be chiefly based upon the cost of making pig iron from them, an approximation as to the effect which decrease in the silica content of ore has upon the cost of snaking pig iron is an important guide in estimating what probable average gain will result from subjecting an ore to a beneficiation process. A search of the literature failed to reveal any detailed statement on this important topic, but fortunately the data are at hand to permit making an approximate calculation of the probable effect. For the purpose of the calculation assume three iron ores with the following composition (natural):

Jan 1, 1924

By Michael A. Trevits

The National Institute for Occupational Safety and Health (NIOSH) in partnership with Strata Products tested the sealing capability of Ventstop®? as part of an ongoing mine fire control and suppression research program. Ventstop®? is a multi-purpose, inflatable device that is produced by Minvent Solutions and is available world wide for use in the metal and nonmetal mining industry. Ventstop®? is also used in the Australian coal industry as a temporary ventilation control device. The device can be quickly deployed, is reusable and can be placed in horizontal and vertical mine voids to control dust, fumes and smoke. Deployment, multi-day inflation and air leakage tests were conducted at the NIOSH Lake Lynn Laboratory to determine the capability and limitations of Ventstop®? in a simulated coal mine setting. During the tests, Ventstop®? was also subjected to low level forces of a nearby methane gas ignition. It is thought that Ventstop®? could be used by the US coal mining industry to temporarily close an underground mine area in response to a fire or spontaneous combustion heating event, to temporarily redirect mine ventilation during longwall equipment moves or during stopping construction. This paper describes this inflatable temporary mine sealing technology and presents the results of the NIOSH tests. Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the views of NIOSH.

Jan 1, 2009

By D. Harrington, F. E. Cash

For a number of years the efforts of the coal -mining industry , as well as of the Bureau of Mines , have been directed largely towards the limitation and prevention of explosions in coal mines . The origin of most explosions is ignition of methane or marsh gas , but the extent and violence of these explosions depend chiefly on the combustible dust present . The Bureau of Mines has conducted a large number of tests on the use of incombustible materials in limiting or preventing widespread explosions . The result of these tests , published in Bulletins 167 and 268 and Technical Paper 386 , proves that incombustible dust can be so applied and maintained in coal mines that the ignition of the mixture of incombustible and combustible dusts , or the propagation of flame by the dust mixture , is impossible ; on the other hand , experience and experiment indicate that watering methods are not reliable as a preventive of general or widespread coal-mine explosions . This report describes the use of " mudite , " a mixture of water and finely divided incombustible soil or dirt applied in some coal mines as a means of attempting to limit or prevent widespread explosions .

Jan 1, 1929

1. PURPOSE The Temporary Face Support System (TFSS) consisting of beams, posts and carrying-emplacing equipment was developed to provide temporary supports between the working face and the permanent roof supports. 2. GENERAL DESCRIPTION The system consists of: ? A Beam And Post Carrier And Deployer (BAPCAD), a self-propelled machine that carries as well as emplaces the beam-and-post sets. ? Lightweight mechanically self-deploying posts designed to safely support a load of 10,000 pounds each. ? Lightweight constant strength beams (bars) capable of sustaining an approximate equally distributed load of 8500 pounds. Note. All referenced figures and drawings are found at the back of this manual.

Jan 1, 1980