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By A. B. Hooker

Nineteen of the installations were on rental contracts 1.L."'1der whtch the lamps belong to the lamp company and are rented by t.½em to the mine operatj.nt; company. · The other nine installations had been upon an O\Vnership-rental basis, by which the lamps had become the property of the renter at the end of 5 years. Five of t.11e rentec installations were en a special contract calling for a guaranteed light output. These contr2.cts were based upon certified . initial performance, with the provision that the lamps be replaced whenever periodic tests of fully charged lamps, taken at random from t..h.e charge racks, showed a light output of less than 80 percent of the certified performance.

Jan 1, 1942

By W. J. Long

The gradual depletion of high-grade mineral deposits and the necessity for development of lower-grade deposits together with the increased demand for nonmetallic minerals has increased the importance of the ore-dressing field during recent years. There is strong need for development of new ore-concentration methods and-machines to keep pace with the constant changing of marketing specifications and requirements resulting owing to the many new uses made of mineral products by the metallurgical industry.

Jan 1, 1948

By A. F. Colombo, D. W. Frommer

Bench- scale tests were made to determine the applicability of flotation as a means of upgrading finished and semifinished magnetic concentrates prepared from reductively roasted iron ores . Both anionic and cationic flotation methods were used to remove siliceous gangue from the magnetic concentrates and produce upgraded products . Seven magnetic concentrates , containing from 6.7 to 13.7 percent SiO2 , were improved by the flotation treatment , yielding final concentrates containing less than 6.0 percent Si02 . Cationic flotation methods were studied on four of the seven samples ; of this group only one sample yielded better results by cationic flotation than by the anionic method .

Jan 1, 1964

By T. H. Dubaniewicz

Fiber-optic technology is progressing rapidly, including the development of fiber-optic sensors for many applications. These sensors have the advantages of high sensitivity, light weight, small size, high bandwidth, and freedom from electromagnetic influences. The U.S. Bureau of Mines is investigating the use of fiber-optic technology to monitor mine atmospheres. This report describes a methane monitor based on differential absorption of infrared light. The monitor can detect methane concentrations as low as 0.2 vol pct as far away as 2 km via fiber-optic cable. The upper range is 100 vol pct methane. Since the system requires no electrical power within the mine, it is intrinsically safe.

Jan 1, 2010

By Charles A. Seitz

This Bureau of Mines report describes an automatic and continuous transducer-drift compensator. The compensator formed a part of the instrumentation used to indicate the saturation by hydrogen of a cryogenic, adsorption column. It has a variable delayed-response characteristic and will respond only to signals having rise times faster than component drift times. Zero drift due to varying ambient conditions and component aging is nullified. Equations relating the output as a function of the input signal are given.

Jan 1, 1981

By d&apos, D. V. Andrea

Nine rock properties were determined for rocks coming from 49 locations and having a wide range of compressive strengths. Plots of the nine rock properties versus each other were prepared. A stepwise multiple linear regression analysis was performed to obtain several equations for predicting compressive strength. Both linear and curvilinear relationships were assumed between compressive strength and the other rock properties. The prediction equations had multiple correlation coefficients ranging from 0.947 for an equation with 1 variable (point load tensile strength) to 0.986 for an equation with 25 variables. Of the properties tested only point load tensile strength could be used alone to estimate compressive strength with fair accuracy.

Jan 1, 1965

By J. J. Geraghty

U.S. Bureau of Mines researchers investigated the development of an innovative transport system for underground coal mining. A one-half commercial-scale bench model was constructed. Novel magnetic levitation (mag-lev) technology was developed. Frictionless and contact-free transport of a prototype materials container and payload has been demonstrated.

Jan 1, 2010

By W. K. Kleysteuber

This report covers the design and testing of a novel bulk materials conveying device by the Bureau of Mines. The transport concept of the device is to create a traveling wave with a steep front so that the bulk material slides and cascades down the front of the wave with some horizontal motion. Ideally, the front should act like a continuous chute. The concept of moving bulk materials along a belt without any forward movement of the belt itself was demonstrated. The conclusions reached were that the mechanism as designed could not overcome the inherent major disadvantages that would make the undulatory conveyor suitable for practical applications.

Jan 1, 1974

By John L. Miller

The synthetic fluormicas may be divided on the basis of silicon content into tetrasilicic, trisilicic, and disilicic. Properties of lead and barium disilicic fluormicas were determined to characterize these two representative members of the disilicic group. Properties described include unit-cell parameters from X-ray diffraction, optical data, chemical composition, density, melting point, and mechanical and dielectric properties. Both the lead and the barium micas were typically monoclinic; neither was sufficiently cleavable to yield usable mica splittings. Both yielded polycrystalline, machinable ceramics with excellent mechanical and dielectric properties.

Jan 1, 1963

By William Cochran

The mineral waste disposal system at the Grace Mine, Morgantown, Pa., was designed to minimize environmental effects while allowing much of the waste from the iron mine, mill, and concentrator to be utilized. Standard cost estimating procedures were used by the Bureau of Mines to determine waste disposal costs. Mill tailings and rock waste disposal costs were estimated at $0.151 and $0.276 per ton, respectively, for the 1965-67 production period. Total waste disposal cost was reduced about $0.015 per ton by utilizing part of the waste as aggregate. The net average cost for disposal of all mineral waste was $0.189 per ton.

Jan 1, 1969

By Lee M. Manna

This report summarizes the program to design, fabricate, install and preliminary test a pneumatic braking system for 10-ton mine haulage cars. Major arrangement drawings are reproduced, pneumatic schematics, parts list and actual developed costs. Recommendations as to system improvements are made.

Jan 1, 1977

By Paul C. Turner

The U.S. Bureau of Mines, through an Interagency Agreement with the U.S. Army Tank-Automotive Command (TACOM), has successfully developed a steel expendable pattern casting process (EPC) for the manufacture of armorplate. The new armor is lighter and more ballistically effective than conventional rolled homogeneous armor (RHA), and costs less. An applique armor spinoff from the program was field-tested during the Gulf War. The applique armor withstood direct impacts from enemy munitions without failure.

Jan 1, 2010

By Frank G. Horino

This report describes an instrument designed by the Bureau of Mines for quantitatively identifying texture of rock surfaces produced by grinding or extremely rough surfaces beyond the range of commercial surface measuring instruments. The transducer for the instrument is a linear variable differential transformer that converts mechanical motion caused by surface roughness, waviness, and lay to an electrical output. The electrical output is recorded graphically as an X-Y plot of the line traversed on the rock surface. Details of the synthesized device and its calibration are given. The sensitivity of the unit is 2 percent of the scale setting of the amplifier. The horizontal scale is adaptable from ¼ inch to 15 inches of specimen length with a sensitivity of 0.01 inch if a 10 to 1 magnification is used and 0.1 inch if a 1 to 1 magnification is used.

Jan 1, 1968

The title of this book, The Phoenix of Natural Disasters: Community Resilience is aptly chosen. ?The Phoenix is a mythical bird that never dies; the phoenix flies far ahead to the front, always scanning the landscape and distant space. It represents our capacity for vision, for collecting sensory information about our environment and the events unfolding within it.? (source: The Feng Shui Handbook, feng shui Master Lam Kam Chuen.) There are Chinese, Japanese, Russian, Egyptian, and Native American counterparts of the phoenix. All of these birds are identified with the sun and depicted as rising from the ashes ? living again. This is the essence of a community after a natural disaster ? they live again. The Phoenix of Natural Disasters: Community Resilience is edited by Kathryn Gow and Douglas Paton who have done an excellent job of creating a relatively seamless transition between chapters with different authors. The content is organized well with the first chapter providing an excellent overview of what is to come and each chapter including an abstract clarifying the focus of the chapter.

Jan 1, 2009

By Alla D. Mah

The heats of combustion of three chromium carbides, Cr23C6, Cr7C3, and Cr3C2, were determined by combustion calorimetry. Heats of formation calculated from the results follow: ?Hf°298 (Cr23C6) = -94.7 ± 5.0 kcal/mole, ?Hf°298 (Cr7C3) = -43.3 ± 1.7 kcal/mole, and ?Hf°298 (Cr3C2) = -22.5 ± 0.8 kcal/mole.

Jan 1, 1969

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Jan 1, 1981

By R. F. Abernethy

A small-scale method was developed for determining the free-swelling index of coal samples of limited quantity, especially the macerals. Results of a series of tests using a 0.3-gram sample correlated well with those by the standard method using a 1-gram sample. The standard and small-scale methods are modified to give unrestricted swelling for those coals having swelling index numbers above 7.

Jan 1, 1971

By R. H. King

A very simple cold-bend test was devised and tested for evaluating thermoplastic jackets used on mine-power-feeder cables. A test sample is bent into a semi-circle whose radius is equal to the minimum bend radius recommended by IPCEA and then cooled to the, desired test temperature (-35°C). While at temperature, the sample is straightened by pulling the cable ends with a winch arrangement. The results show that of the jackets tested, those which cannot withstand the test literally burst when the sample is straightened.

Jan 1, 1978

By W. T. Millar

Field reconnaissance and laboratory tests on clay from South Windsor, Hartford County, Conn., indicate that the clay is suitable for lightweight aggregate raw material. Exploration of the deposit supports the conclusion that the reserves of clay are sufficient for economical mining operations to produce lightweight aggregate. Preliminary tests indicated that the clay has a short bloating range. Initial expansion occurred at 2,000° F, and at 2,100° F the clay was slightly overfired and sticky. Rotary kiln tests verified the preliminary data, and these tests showed that the clay would make a good lightweight aggregate if the processing temperature and the kiln feed sizes were closely controlled. Lightweight concrete made from the processed aggregate had properties comparable to those of concrete made from a commercial clay aggregate.

Jan 1, 1964

By A. R. Kirchner

This paper describing the practice at the concentrator of the Minas de Matahambre, S. A., is one of a series being; prepared by the Bureau f Mines on milling methods and costs. The Minas de Matahambre, S. A., concentrator treats the production of the Matahambre mine and has a capacity of 1,300 tons of copper ore per day by selective flotation. During the year 1930 the heads averaged 4.55 per cent copper, the concentrates 29.20 per cent copper and the recovery was 95.96 per cent.

Jan 1, 1931