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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 Samuel A. Goldberg

The Federal Coal Mine Health and Safety Act of 1969 delegated to the Bureau of Mines a yearly program of health inspections. Respirable coal mine dust concentrations are measured by Bureau inspectors. Samples of respirable coal mine dust are weighed to determine dust concentration and then analyzed for ash and quartz content. This paper describes the laboratory procedure for determining the percent quartz in the respirable coal mine dust samples.

Jan 1, 1972

By Richard J. Bielicki

The possibility of replacing the brattice cloth closest to the coal mine working face with an air curtain mounted on top of a continuous-mining machine or with a diffuser fan was explored by the Bureau of Mines. Preliminary tests conducted at a full-scale model working face with the brattice end set at 18 feet showed that the air curtain improved face ventilation only slightly and was not nearly as effective as placing the brattice at 10 feet. A 2,000-ft3/min diffuser was more effective than the air curtain. It is concluded that the air curtain probably could not function as a line brattice extension, although the diffuser fan may have some potential.

Jan 1, 1975

By E. J. Matson

The Little Castle Creek chromite deposit was examined in February and May 1941, respectively, by W. O. Vandenburg and O. H. Metzger, engineers of the Bureau of Mines. The Federal Geological Survey started a magnetometer survey of the area in November 1940 and completed its work during April and May 1941. Field work by the Bureau of Mines was conducted during May and June 1941. The purpose of the Bureau of Mines investigation was to search for a continuation of the chromite mineralization. The property at one time was the largest chromite producer in California.

Jan 1, 1949

By R. D. Currie

Many coal companies have a system for checking men into and out of the mine , and generally such systems appear to be perfectly sound and adequate . However , when the real test comes at the time of a mine disaster , too often the system is found to have failed , and hours and sometimes days pass before it is known how many men are in the mine and who they are . Most of the systems in use , when properly maintained , are adequate for the routine work of the mine , and some of them may prove adequate at the time of a mine disaster . All systems , however , depend upon proper supervision and strict adherence to the system .

Jun 1, 1930

By T. D. Ralston

This Bureau of Mines report presents a mathematical model for heterogeneously catalyzed chemical reactors operating under turbulent conditions. The model includes reaction kinetics on the catalyst surface as well as diffusion of the reacting components within the reactor. Three applications of the model to tube-wall methanation reactors are discussed. The first application is a computation of catalyst activity from measured reactor data. This result is then used in a reactor sizing problem and a problem of reactor simulation with recycle. In addition to the reactor model, a novel approach to solving the recycled reactor problem is given.

Jan 1, 1974

By Edward Cogan

Equilibrium phase diagram studies of zirconium- rare earth metal alloys by the Bureau of Mines at its Albany Metallurgy Research Center prompted the development of a rapid gravimetric method for determining rare earths in zirconium in which the rare earths are absorbed from sulfuric acid solution of the alloy on a cation exchange resin . The sample in 10 percent H2SO4 is introduced into the column , the zirconium is eluted with 10 percent H2SO4 , and the rare earths are eluted with (NH4 )2SO4 solution and precipitated with NH4OH . A tracer technique was employed to determine the efficiency of the procedure . Y203 and europium 154 - 152 (Oak Ridge ) were added to 10 g of zirconium and taken through the entire procedure . Recovery averaged 97.6 percent on 0.002 μg europium in the rare earth fraction . Rare earths were determined in the range 0.10 to 90 percent .

Jan 1, 1964

By John S. Berber

Tar produced as a byproduct from low-temperature carbonization of coal contains only small amounts of valuable lower boiling tar acids but relatively high percentages of high-boiling tar acids. These high-boiling tar acids are characterized by a high degree of alkylation and can be converted into the lower boiling homologs by catalytic treatment to remove the alkyl groups or decrease their chain lengths.

Jan 1, 1965

By RUDULF KUDLICH

Pennsylvania anthracite coal is almost universally recognized to be the solid fuel best suited for domestic use when cleanliness , convenience and cost are considered . At various times and in various localities , however, conditions so affect the supply that it becomes insufficient or is too high in price and recourse must be had to other fuels as substitutes . In practically every district in the United States where anthracite has been the common domestic fuel , some other fuel is available as a substitute . In even the most severe climates such fuels are used either as emergency substitutes for anthracite , or as the ordinary domestic fuel . There may be some drawback to the use of such fuel , such as the need of more frequent attention to the furnace , smoke , soot and dust , in the case of solid fuels lower in price than anthracite , but these inconveniences must be accepted as necessary accompaniments to a decreased fuel bill . The cleanliness and ease of handling anthracite in the house must be considered in the light of a luxury and a higher cost of heating with this fuel must be expected . That a growing number of people are willing to pay for such added convenience is evident from the increasing mumber of heating installations using oil , gas and electricity , all of which are more convenient and usually more expensive even than anthracite .

Aug 1, 1923

By J. S. Hansen

The U.S. Bureau of Mines developed a system for casting unique, slotted steel armor by modifying the conventional expendable pattern casting (EPC) process that is normally used for making aluminum castings. Three innovations were added to the EPC process to make the successful adaptation: (1) Vacuum was applied to sand molds, (2) continuous narrow-necked feeding systems were used to permit the casting of thin walls, and (3) fixtures were designed to prevent pattern damage and to hold critical casting tolerances, Potential problems and defects are described.

Jan 1, 2010

By Todd M. Ruff

Researchers at the National Institute for Occupational Safety and Health (NIOSH) are studying methods to prevent workers from being entangled in machinery used at mining operations. An analysis of mining accidents in the United States that resulted in a fatality or permanent disability from 2000 through 2005 showed 438 severe incidents that involved contact with machinery or equipment, an average of 73 per year. Researchers determined that the most common machinery involved in these severe accidents was conveyors. Also, a significant portion of the accidents occurred during machine maintenance and repair. Researchers are focusing on improved methods to prevent unintentional machine startup during maintenance activity and methods to detect workers near moving machine components. One new technology that shows promise for this application is intelligent video. Popular in the surveillance and security industries, these systems use cameras and computerized video analysis techniques to automatically detect the presence of people in preset zones within the camera?s field of view. A preliminary study has been initiated to determine if this technology could reliably detect the presence of workers in hazardous locations near machinery. Possible advantages of the use of this technology include improved detection zone demarcation and improved ability to distinguish between hazardous and non-hazardous proximity, compared to conventional proximity sensor techniques. Initial tests to detect a person near a conveyor system in daylight conditions showed promising results. A description of the technology, test procedures and results, implementation challenges, and future research needs are discussed.

Jan 1, 2008

By J. Whyatt

A variety of dynamic failure cases with regional impact were described at a bump symposium held in 1958. These types of events, while rare, are of particular interest because their ability to impact a large area has disaster potential. These cases can be grouped into two broad classes of events by mechanism. These are (1) slip along steeply dipping faults and (2) fracturing of strong strata above, or below, the coal seam. Both failure modes produce dynamic or ?shock? loads on the perimeter (roof, rib, floor) of mine openings. Special consideration should be given to these failure modes in planning of deep coal mines since their occurrence is not within the professional experience of many contemporary workers, and their potential is not evaluated by many of the analysis tools commonly used to evaluate hazards in coal mine plans.

Jan 1, 2009

By David K. Ingram

The development of large open surface fractures over mined-out coal longwall panels is the focus of this U.S. Bureau of Mines report. The research concentrates on defining the fractures characteristics and their controlling variables. The investigation was conducted at two mines in south-central West Virginia. All but one of the fractures are subparallel to the trend of the underlying longwall panel. One fracture is perpendicular to the trend of a longwall panel. Overall length of the fractures ranges from 60 to 900 ft. In cross section they are V-shaped, ranging from a couple of inches to 25 ft in width at the surface, but narrowing as they increase in depth. Fracture depth varies from a few inches to over 50 ft into bedrock. A vertical fracture or joint plane was observed in the bedrock at several open zones along the fractures. All of the fractures vary in elevation and do not parallel surface contours. The fractures are aligned with local joint trends, they correlate with longwall development, and they are situated in an increased tensional area over the mined out longwall panels. These observations indicate that the fractures are tensional openings along preexisting joint planes possibly triggered by longwall mining.

Jan 1, 1989

By E. L. Litchfield

This report of work by the Federal Bureau of Mines has two primary objectives: A survey of the present status and usefulness of the minimum ignition-energy concept, and the presentation of recent data that are believed to bear on the safety problem associated with the ignition of combustible gases by electric discharges. The minimum ignition-energy concept has widespread applicability, especially to safety. The primary obstacle in making theoretical calculations of the requisite ignition energy is the lack of data on chemical kinetics and flame hydrodynamics. The new data on electrical ignition are representative of the great increase in knowledge that can be achieved by proper utilization of geometrical and electrical characteristics associated with the ignition source. CONCEPT OF MINIMUM IGNITION ENERGY The basic concept of a minimum ignition energy (the minimum amount of energy required to cause ignition) follows quite naturally from general physical principles and from the stability (lack of chemical reaction) of the gaseous mixture under the initial conditions. It also follows that if, as a first condition, lossless, instantaneous, and spatially localized energy can be injected and, as a second condition, the relaxation time for conversion of this type of energy to the type required for the reaction is short compared to some characteristic time scale of the ignition phenomenon, the energy requirements will be essentially independent of the type of energy source. Even if condition one cannot be fulfilled, it is sometimes possible to estimate the energy content of the gas required for ignition, and under these circumstances, condition one is fulfilled in effect. There are several instances where results can be interpreted for circumstances that effectively satisfy conditions one and two; these will be discussed later.

Jan 1, 1960

By G. M. Martinez

A cell concept adaptable to large-scale electrowinning of zirconium metal from zirconium tetrachloride was investigated by the Federal Bureau of Mines. Tests were made in twin cells, each 12 inches in diameter by 33 inches long. Electrowinning was performed in one chamber from which the electrolyte was transferred after electrolysis to the other chamber where it was renewed by the introduction of ZrC14 by direct sublimation. The formation of a salt plug in the connecting pipe provided a seal between the chambers. Optimum electrolyte composition, with respect to quality of the metal product (91 pct meeting ASTM standards except for the oxygen content) and current-carrying capability (about 350 amp) was determined to be 16.7 wt-pct NaF-83.3 wt-pct NaCl mixture plus ZrC14 equal to about 3 wt-pct zirconium. A twin-cell design incorporating the unit operations covered by this investigation is proposed.

Jan 1, 1976

By K. Kar, M. Gautam, J. T. Jurewicz

The 10-mm Dorr-Oliver cyclone has been widely used as a personal sampler for size selective sampling of particles within the respirable range (Dp < 10 gm). Because of their inertia, the particles are unable to follow the swirling flow (outer vortex) within the cyclone. The particles migrate to the bottom of the cyclone, depending on their size, and get trapped into the inner vortex which leads to an eventual blow-off from the top of the cyclone. By measuring the size distribution of the particles in the free stream and in the collected sample, the aspiration efficiency of the cyclone can be calculated. Velocity difference between the free stream and sampling velocity. Inlet orientation, particle impaction and deposition, particle inertia and free stream turbulence result in the departure of the aspiration efficiency from unity and this, in turn, leads to inlet bias. Although the effect of inlet bias on sampling efficiency has been investigated in past, the results lack detailed information and show only some general trend. In this effort, a systematic, in-depth experimental work on the effect of inlet bias on the sampling efficiency has been undertaken using non-intrusive Laser Doppler Anemometry (LDA), Aerodynamic Particle Sizer (APS) and impactors.

Mar 1, 1992

By P. G. Clites

This study was undertaken to determine the effect of consumable-electrode vacuum arc melting on the properties of copper and to determine the applicability of the process to the production of cast shapes of copper. Ingots and castings were produced from electrolytic tough pitch copper (ASTM designation ETP), from electrolytic cathode copper (ASTM designation CATH), and from oxygen-free copper (ASTM designation OF). The products of this study were evaluated to determine the effect of the melting process on the removal of impurities from the copper and on the physical properties of the copper. The results indicate that consumable-electrode arc melting can be satisfactorily applied to the melting and casting of copper. Ingots prepared directly from electrolytic cathode copper contained slightly higher levels of impurities than are found in commercial oxygen-free copper, Excellent results were obtained with centrifugal castings of unalloyed copper, and reasonably successful static castings can be produced if proper mold and gating systems are employed.

Jan 1, 1963

By Thomas E. Marshall, Patrick A. Kinek, Gerald L. Finfinger

The purpose of this investigation was to evaluate the integrity of the existing shutoff valves and actuators used under high-temperature conditions in the Bureau of Mines&apos; horizontal borehole methane drainage pipe- line system and to determine the potential for improvement in the system. In the field tests, both fire-safe ball valves and standard brass ball valves were initially subjected to a 30-min pan fire without thermal protection. Neither valve could maintain line pressure beyond 11 min in a fire that reached temperatures between 500° and 700° C. Based on the test results, it was concluded that the brass ball valve used in the Bureau&apos;s methane drainage pipeline system can be retrofitted with an inexpensive "fire bag" to substantially increase its integrity under mine fire conditions.

Jan 1, 1986

By A. B. Hooker, L. C. IlsLey

In lare-scal e blasting, it is customary to fire me.l'\Y shot.!:l simu1. taneously. The electric !atonators ara usually conneced in seies, ard are fired either from a power circuit or :from a blasting ma.chine with large capacity, operated by hand. "!hen :'::ri111; with a blasting ca.chine, trouble with missed shots has been freqi.,.ently e>:pert0nced.. Unit1:i:' thes ,:::rcu:ns tances, the shots that fail to fire are often a gr"up in the t.:E"nter r,f t>e series, Various explaz,.a.tions hs.ve been given as to the cause of the failurs. Tis paper covers a few tests made cy the electrical section of tl:.e Dti..'t'cau. cf Mines, wh;.r.;h may be helpful in understanding the -probable cuse of tl1e misfiring of c.:anter shots, Wh3tever th9 source ot the firir. current generator, magneto, or batter, the CUl"rent delivered th:·01.1.gh a shot-f:?·ing circu.it is determined by t.ae total resistance of ,;he clrcili +.; c:1nd all cure:it leaving th9 p,si tive terminal must return to tre negative te1-minal. If a. metallic circuit is well i1,.sul.:tted, praeti­ccl. l;1 a.ll of the t.'Urrent keepo within the circu.it; but in a. shot-!11·.irig ci.rc1li t, Nhere the ·.vires f:ll·e often 1n c.c,i.cact with the eru:"!ih as i11 wet holer., end whero the ins".lla.tion of the leg wires :i. inadecpa.te to prc·,ent lea.l.tage, the current ma.v tu.e v a.r ious pa the: thro-.. .. gh the nr r. earth.

Aug 1, 1922

By L. C. IlsLey

It is most unfortunate that a few must often suffer , and perhaps die , that many may benefit from a fuller appreciation of the dangers surrounding mining operations , and the proper use of safeguards designed to offset these dangers . This has been the case during the last few months in the anthracite field , where several explosions , resulting in burnings and fatalities , were undoubtedly caused by the use of defective or improperly assembled flame safety lamps . Had this same lack of understanding regarding the proper assembly of this safety device , and had the same indifference on the part of the user in keeping the lamps locked at all times and in proper condition , been permitted in a region where the coal dust was explosive , a terrible disaster would surely have resulted . In nearly every coal -mining country , including the United States , the Davy and Clanny type of lamp has been superseded , and rightly so , by some kind of bonneted lamp . Bonneted lamps , especially of the naphtha type , while much safer than the unbonneted , have more parts and need more care in assembling . For this reason the burden of responsibility for their being properly assembled rests with the lamp man ; therefore , it is extremely important that only competent , conscientious men be given this work .

Dec 1, 1921