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By Gene Asai

Properties obtained for columbium carbide-carbon castings ranging in car-bon content from 12 to 17 weight-percent were compared with those of hot-pressed composites of similar composition. The properties were oxidation resistance in static air between 500° and 700° C, linear thermal expansion between 20° and 2,400° C, electrical resistivity between 20° and 1,500° C; microhardness between 20° and 1,500° C, and modulus of rupture between 1,300° and 1,800° C. CbC-C castings differed markedly from hot-pressed material with respect to microstructure, electrical resistivity, and modulus of rupture, but behaved quite similarly with respect to oxidation resistance, thermal expansion, and hot hardness. In oxidation resistance, thermal expansion, and hot hardness both materials were independent of carbon content. Both castings and hot-pressed composites oxidize rapidly in air above 600° C, have thermal expansion coefficients very similar to columbium metal, and the logarithm of the hardness decreases linearly with increasing temperature. The microstructures of hot-pressed composites contained varying amounts of graphite in a CbC matrix but did not contain significant amounts of a eutectic structure present in all castings, nor did they contain graphite needles which were present in the hypereutectic castings. The higher electrical resistivity of hypereutectic castings over hypereutectic hot pressings was attributed to the presence of highly oriented graphite needles in the castings. The modulus of rupture of castings was 1-1/2 to 2 times that of hot-pressed composites. Both materials displayed bend ductility above 1,800° C.

Jan 1, 1971

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 Edward F. Divers

The Bureau of Mines recently tested a sideboard device that is designed to act as an extension of conventional brattice, thus improving face ventilation of developing room-and-pillar-type coal mining. In these laboratory tests, an 8-foot-long rigid sideboard was mounted vertically along the left fender of a full-scale-model ripper-type continuous mining machine, rising to the mine roof to provide an air seal. It extended from the auger support frame pivot point outby along the fender. A novel water spray manifold was used to form an air seal between the sideboard and brattice. Tests showed improvement in face ventilation with the prototype device, and also demonstrated that water sprays can form an effective air seal over a fairly wide pressure range. Based on this preliminary study, subsequent improvements may make the sideboard concept much more effective, thus affording a simple, inexpensive technique to improve the effectiveness of face ventilation.

Jan 1, 1979

By R. E. Stiles

The modified perchloric--EDTA method devised by the Bureau of Mines for the determination of copper in high-grade samples gives results that are more precise and more accurate than those from the classical sulfuric-iodometric method. Although the perchloric--EDTA method is more costly than the conventional method, the savings in time alone largely offsets this difference. Specifically, the modifications wade in the more conventional procedure comprise (1) use of perchloric acid instead of sulfuric acid for dissolution of copper minerals, (2) precipitation of copper as copper sulfide from dilute perchloric acid solution, (3) wet oxidation and dissolution of the precipitated copper sulfide, (4) use of larger amounts of indicator than those employed in the Schwarzenbach method of titrating low-tenor copper solutions with disodium ethylenedinitri10-tetraacetate and murexide indicator, and (5) use of refrigeration to partially stabilize aqueous solutions of the indicator.

Jan 1, 1966

By Albert A. Munsch

The Munsch National First-Aid Instructors Association had its inception during the teaching of a Federal Bureau of Mines first-aid instructors' class at McPherson, Kans., under a cooperative plan of first-aid training. Upon completion of- the course on July 1, 1938 members of the class organized the charter chapter of the association under the name of McPherson (Kans.) District Charter Chapter No. 1. On July 1, 1941, 3 years after the founding of the association, there were 15 chapters in the national council -7 in Kansas, 3 in Oklahoma, 2 in Texas, 2 in New Mexico, and 1 in Arkansas. Although the pioneer work of the association was done in the petroleum industry, the plan will be of even greater benefit to a district in which there are various types of plants, mince, and operations of the mineral and allied industries. ACKNOWLEDGMENTS The writer appreciates the cooperation and assistance of the following persons: S. P. Redfearn, safety engineer, Globe Oil & Refining Co. and affiliated companies, Wichita, Kans., and H. (Chief) Moore supervisor of safety meetings, Shell Oil Co., Inc., McPherson, Kans., for their untiring efforts and enthusiasm in organizing an- attending the first class, organizing three other classes, and helping to plan the work of the association

Jan 1, 1942

By John M. Dower, Ralph W. Plummer, Terrence J. Stobbe, Hyunwook Kim

"The relationship between exposure to coal mine dust and the development of various respiratory diseases is well recognized. The cause of these diseases however. Is still uncertain. To study this cause-effect relationship, It Is necessary to characterize the coal mine dust In terms of the quantity of dust present and mineral content of the dust. Dust samples were collected using a Portable Continuous Aerosol Monitor (PCAM) and 4-stage cassette Impactors at various locations in an upper Freeport seam coal mine In West Virginia. The samples were analyzed using an X-ray microdiffraction film technique and energy dispersive scanning electron microscopy. This paper presents the results of the first phase of this characterization work which Includes determining the size distribution of the dust and the mineral content of the size intervals.IntroductionDiseases associated with dusts in coal mine environments continue to afflict miners in today's modem mines. These diseases still persist because, as Olishifski points out an employee rarely experiences exposures to a single environmental stress but rather to an Intricate Interplay of multiple stresses.(1) In the case of coal mining the multiple stresses are varying sizes of dust particles originating from coal imbedded minerals. Immediate roof strata bottom strata. Incombustible rock and the coal itself. The site of this Intricate Interplay Is the miner's lungs and the resulting diseases are a function of the composite dust exposures.The proper study of coal mine dust toxicity requires that the dusts used replicate existing coal and mineral dust compositions in their relevant size fractions. The purpose of this project is to develop the size and mineral content data necessary to support this ongoing toxicological effort.Existing coal mining standards and regulations also address total and respirable dust exposures. These dust terms refer to both the quality and quantity of the dust segment in the mine atmosphere. Dust quality addresses its coal and mineral content. whereas dust quantity Is described by mass per unit volume (mg/m3) The comprehensive characterization of coal mine dust exposures will enable revision of these standards and regulations to address the specific minerals and size fractions found to be toxic to human lung tissue."

Mar 1, 1989

By George S. Koch

A statistical analysis of silver assay data from rotary-drill-hole cut-tings and diamond-drill-hole cores from the Round Mountain prospect, Custer County, Colo., demonstrates several useful methods for estimating grades and tonnages of ore from the drilling of wide-spaced holes in disseminated deposits of precious metals. A new method of are appraisal is introduced which estimates grade and tonnage of are by calculating convex hulls (smallest convex polygons) for sample points with assay values above specified cutoff grades. Analyses of variance compare the consistency of data from rotary-and diamond-drill holes, from rotary-drill holes sampled at 2-and 4-foot intervals, from two methods of sample preparation, and from atomic-absorption and fire assaying. Evidently, data from the two types of drill holes, from holes sampled at the two intervals, and from different methods of preparation are in agreement. Atomic-absorption silver values are consistently lower than fire-assay silver values.

Jan 1, 1971

Determine the minimum waterflow rate needed for effective control of dust produced by cutting machines used to mine water-soluble ores. Approach Conventional wet-bar cutting techniques were studied to evaluate their dust control performance, and the optimum water flow needed for dust suppression was determined. Wet-bar type cutting techniques are used to help control mine dust by keeping the cutting chain wet. As the chain cuts the kerf, it dampens the dust produced by the cutting action at the point of generation. The Bureau, under contract, evaluated three basic wet-bar techniques, as shown in the diagram: water-trickle system A uses a gravity-feed or low-pressure (less than 50 psi) pump to send water through the bar and to discharge it at the bar tip. Water-spray system B uses a low-pressure spray nozzle located at the front of the cutter head. For protection the nozzle can be located within the cutter

Jan 1, 1982

Reduce the dust exposure to the operator of a longwall shearer with a novel foam spray system. Approach Discharge foam through the nozzles of a shearer drum so that foam and coal are better mixed. How It Works Bureau of Mines research showed that two very important principles for successful application of foam are: (1) moisture distribution and (2) degree of mixing. Foam can distribute a given quantity of moisture much more evenly over a large surface area. Successful Bureau tests of foam for dust control always involve a high degree of mixing between the foam and the material, Mixing, permits a greater distribution of foam throughout the mined product. The most suitable location of foam application would be at the point where the dust is generated, before the dust becomes airborne. Foam nozzles located in the cutter drum (pick face foaming or ejecting foam through scroll sprays) will suppress dust close to its source.

Jan 1, 1989

By Hal H. Engel

This publication was written in response to numerous requests for information about the Federal Bureau of Mines' "Demonstrated Lecture on Flame Propagation and Permissible and Explosion-Proof Electrical Equipment." The requests came principally from: (1) Persons wanting to know more about the demonstration before requesting it for groups they represented; (2) persons wishing advance information to help publicize a meeting where the demonstration was to be given; and (3) members of audiences desiring something to help them remember the salient points, facts, and figures presented during the lecture and demonstration. The purpose of the demonstration that accompanies the lecture is to show: (1) Variations in flame speed and pressure at various percentages of flammable gas within the flammable range; (2) effect of flame speed on the "pressure piling" within the area confining the mixture; and (3) the application of flame speed and pressure piling to the combustion of surrounding gas and to the design and maintenance of electrical equipment used in hazardous locations.

Jan 1, 1960

Reduce potential for steering errors during tramming of articulated vehicles, particularly when the operator is seated to the rear of the machine pivot point and is tramming in reverse. Approach Position-sensing and feedback cylinders were applied to the steering cylinders of two S&S cleanup tractors to cause the steering-control lever to match the orientation of the vehicle sections. The vehicles were tested in two working mines. How It Works A position-sensing cylinder (see Figure 1, Item A) is attached to one of the steering cylinders in the cleanup tractor steering system. As the steering cylinder piston rod is actuated by movement of the control lever, hydraulic oil flows from the position sensing cylinder to the feedbck-cylinder (B), causing the feedback-cylinder piston and rod to move. The outside end of the rod repositions the the steering-control lever until its angular position corresponds to the orientation of the vehicle sections.

Jan 1, 1978

Perform laboratory tests to measure the vibration attenuation characteristics of off-road vehicle operator seats for various types of seat suspensions, cushions, and seat adjustment settings. Background A study was conducted by the U.S. Bureau of Mines to determine the probability of whole-body vibration (WBV) exposure for a large class of off-road machinery operating in surface coal mines. The study determined that mere than 40 pct of off-road equipment operators were exposed to WBV exceeding the standard fatigue-decreased-proficiency (FDP) level defined by the International Standards Organization in its guideline ISO standard 2631. The tire-terrain interaction of a moving vehicle generates vibrations that are transmitted through the ve¬hicle suspension, cab mounting, and seat. The final point of transmission of vehicle vibration to the operator is through the scat. A seat that provides good vibration isolation and allows good vehicle control is of prime importance to operator safety and health.

Jan 1, 1993

By S. P. Signer

The Bureau of Mines conducted a series of field tests to improve the understanding of the support interaction mechanics between fully grouted bolts and coal mine roofs and to help lay the foundation for improved design and evaluation techniques. Strain gauges were installed on 14 fully grouted bolts placed in shale roof rock at four mines in Colorado, Illinois, and Pennsylvania to determine how load was transferred between the bolts and the rock. The results of field tests on elastic bolt behavior compared well with previous laboratory work and numerical models. The field tests showed that the anchorage length of grouted bolts installed in shale was slightly longer than the anchorage length determined in laboratory tests conducted in concrete blocks. The field results produced more variability because of geological variations. Tests run past the yield point of the steel bolt indicate that the yield zone varies significantly and translates down the length of the bolt anywhere from 4 to 22 in.

Jan 1, 1990

"Introduction.The Bureau of Mines has taken up the problem of determining a method or methods whereby underground compensation insurance rates for metal-mining companies can be equalized in proportion to the underground hazards involved. This study has been started by the writer with the assistance of Mr. I. M. Wolfin* as consultant.The present paper briefly reviews the origin of accident compensation, gives a digest of State compensation laws, and describes types of insurance carriers. This will be followed by study of the basis of premium rate, risk differentials, and cost of compensation insurance to mine operators. These data will be supplemented by an analysis of the accident hazards in different mining methods and practices, and the severity and frequency of accidents classified by time lost and period of exposure to hazard, for different States, mining methods, occupations and nationalities. Attention will be given to standardized preventives for underground accidents in metal mines, and, finally, the classification of underground metal-mining hazard for workmen's compensation insurance premium rating."

Mar 1, 1924

By Carlton E. Brown

In 1935 , Brown and Yant / described a microprojector ( microscopic arrangement for projecting images on a screen ) for use in counting and measuring the size of dust particles in Owens - jet dust - counter and simila dry samples of dust collected from the air . In 1938 Brown and others , described a modification of this microprojector that could be used also in counting dust in impinger samples . Microprojectors of this second type have been set up by many mining companies and others and have been made commercially available . Hamly and Pullen5/ described a modification of this microprojector for use in making rapid comparative estimates on konimeter samples and other determinations . This report contains information on still another modification named the "midget microprojector " because of its small size .

Sep 1, 1944

By E. J. Gleim

In the movement of self-controlled direct-current machinery, particularly shortwall cutting, machines, from one place to another in coal mires, "nipping" or it stinging" has been practiced quite commonly. These terms refer to the method of obtaining current for propelling or tramming the machines along trolley haulageways by sliding the trolley trip (hook or nip), which terminates one conductor of the trailing cable, along the trolley wire. This is usually done by the machine operator or runner while sitting on the machine truck and holding the nip terminal against the trolley wire as the machine travels along the rails. This procedure is objectionable for several reasons. Under the best conditions, the area of contact between the nip and trolley wire is snail end, consequently, sparking and flashing ore most likely to be continuous as the machine proceeds. This is undesirable, not only because of the detrimental effect of electric flashes upon eyesight, but because of the pitting and roughening the trolley wheels which decrease the efficiency of current collection by locomotive trolley wheels and shoes and at the same time shorten their useful life by increased wear.

Jan 1, 1939

By I. W. ROBERTSON, G. G. Oberfell, G. A. Burrell

The Bureau of Mines, in pursuing investigations looking to greater safety in mining, has analyzed samples of the air in many different coal mines in the United States, and has studied the analyses. This report presents the results of one phase of this study and shows how atmospheric air, after entering a coal mine, loses oxygen and gains carbon dioxide with resulting formation of so-called black damp. Also the report discusses the effects of the constituents of black damp on men, on the burning of oil and acetylene lamps, and on the ex- plosibility of methane. The term "black damp" was and still is widely used to designate accumulations of carbon dioxide, but a more exact definition of black damp, as Haldane, the English physiologist, has pointed out, is an accumulation of carbon dioxide and nitrogen in proportions larger than those found in atmospheric air. The reasons for preferring Hal- dane's definition are given on succeeding pages.

Jan 1, 1916

By R. C. Buehl, J. P. Riott, M. B. Royer

Sponge iron is the metallic product resulting from the reduction (removal of combined oxygen) of iron ore or other iron oxides at a temperature below the fusion point of iron. It has been used for many years in the production of certain grades of high-quality steel, such as tool and cutlery steels. The sponge iron available commercially in limited quantities for such use was produced from high-grade ores that were almost free from the contaminating elements that are generally considered detrimental to the production of certain grades of carbon tool steel. Interest in sponge iron as a scrap substitute was revived when World War II began, when the serious shortage of scrap metals for use in the production of armament caused great concern as to whether steel production could be maintained at the rate necessary for vigorous prosecution of the war effort. Also, because of the severe shortage, steel manufacturers…

Jun 1, 1947

By R. L. Grant

At the Eighth International Conference of the Directors of Safety in Mines Research, Sartorius and Thouzea5/ presented and discussed data obtained in explosives tests made under varying conditions of humidity. These tests showed that there was less probability of explosives failure when the humidity of the testing gallery atmosphere was high. As it is to be expected that the relative humidity of mine atmospheres where permissible explosives are used will not be identical with that of the test-gallery atmospheres, the influence of atmospheric moisture upon the incendivity of permissible explosives is of the utmost importance if decreasing humidity reduces the relative safety of an explosive. Because of this and because the question has recurred frequently in discussions of gallery testing at Bruceton, Pa., it was decided to investigate the effect of humidity and ambient temperature on the ignition of firedamp by explosives, applying the small-scale gallery methods developed at the Bureau of Mines and used earlier to study the fundamental causes of such ignitions.6 7 8/

Jan 1, 1956

By D. W. Frommer, M. M. Fine

"INTRODUCTION Laboratory mineral-dressing investigations covered by this report show that ores from Montgomery County, Ark., and Morgan County, Mo., are potential sources of barite and zinc. Fine grinding and froth flotation yielded drilling-grade barite from the former and chemical-grade barite and zinc concentrates from the latter.Samples from these deposits were subjected to a laboratory investigation to develop an economic and feasible treatment. The Arkansas ore, submitted by the Husky Refining Co., consisted of an intimate mixture of the economic mineral and quartz. Fine grinding and fatty acid flotation were utilized to effect a good recovery of a drilling-grade product. The other was a zinc-barite ore submitted by the Rocky Ford Mining Co., Stover, Mo. There was no problem in the recovery of zinc (most of which occurred as sphalerite), but the recovery of barite by flotation was complicated by the presence of gangue carbonates. Ultimately, an excellent recovery of barite was achieved with a relatively new type of flotation promoter, petroleum sulfonate.In recent years, barite has become one of the major industrial minerals as an essential ingredient in heavy drilling fluids, pigments, and chemicals. New sources of this important commodity are always interesting; thus, it is the purpose of this report to present information that may permit commercial exploitation of two deposits not in production."

May 1, 1952