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By Parviz F. Rad

The increased use of tunnel boring machines (TBM) has stimulated laboratory research to optimize the cutting parameters of these machines with the objective of increasing machine efficiency and penetration rate. Laboratory-scale rock cutting experiments have succeeded in identifying many of the important parameters involved in rock-cutter interaction. Although scaling factors may be required to apply the results directly, the concepts developed can be used qualitatively as design guidelines for boring machines. The Bureau of Mines Twin Cities Mining Research Center has recently developed a large-scale rock cutting device (RCD) that will simulate many of the operating parameters of the tunnel boring machines in the laboratory under a controlled environment. The results of the experiments with this device will be directly applicable to the design of TBM's.

Jan 1, 1973

By Paul B. Harder

Round Mountain Gold (RMG) in central Nevada, reports that over a nine-year period and a million operating hours, its fleet of 150-ton and 190-ton haul trucks has averaged better than 93% availability, with some of the trucks approaching 70,000 operating hours. Repair costs have been far below industry averages. Mine operations manager Pete Kesl credits the high availability and low repair costs to a succession of Product Support Agreements between RMG and Caterpillar dealer Cashman Equipment. He adds that good equipment and a high level of trust and co­operation between all parties to these agreements have been essential to their success at Round Mountain.

Jan 1, 1998

By L. B. Pankratz

Low-temperature heat capacities, high-temperature enthalpy increments, and the enthalpy of formation at 298° K were determined calorimetrically for vanadium subnitride (VN0.465). The low-temperature investigation gave S°298.15 = 6.379 ±0.005 cal/deg mole, and a combustion calorimeter investiga¬tion provided ?Hf°298.15 = -31.80 ±0.60 kcal/mole. The two quantities were combined with the high-temperature data to give standard values of enthalpies of formation and free energies of formation above 298° K. These and related thermodynamic functions were tabulated to 1,800° K. Similar data are included in the range of 298° to 1,600° K for the mononitride, VN.

Jan 1, 1971

By Will H. Coghill

Recent work on beneficiation of the .Alabama red iron ores and ferruginous sandstones has brought out interesting new facts on particle-size reduction that axe a valuable supplement to what is already known.4/ The work was done by the Southern Experiment Station of the Bureau of Mines in cooperation with-the University of Alabama, University, Ala., on two samples from the Birmingham district. One was an oolitic red iron ore containing about 35 percent iron; the other was a ferruginous sandstone containing about 25 percent iron, particularly attractive because of its low phosphorus content. In both samples rounded quartz (sand) grains were embedded in an oolitic, "onion skin" matrix of hematite. The hematite carries varying amounts of clay, which limits the grade of concentrate that can be made. The clayey hematite is soft, so that the rock crumbles readily under pressure. The sand grains shell out like corn,, and without much exaggeration the mill used for differential grinding might be called a "sheller,"

Jan 1, 1940

By Will H. Coghill

Recent work on beneficiation of the .Alabama red iron ores and ferruginous sandstones has brought out interesting new facts on particle-size reduction that axe a valuable supplement to what is already known.4/ The work was done by the Southern Experiment Station of the Bureau of Mines in cooperation with the University of Alabama, University, Ala., on two samples from the Birmingham district. One was an oolitic red iron ore containing about 35 percent iron; the other was a ferruginous sandstone containing about 25 percent iron, particularly attractive because of its low phosphorus content. In both samples rounded quartz (sand) grains were embedded in an oolitie, "onion skin" matrix of hematite. The hematite carries varying amounts of clay,-which limits the grade of concentrate that can be made. The clayey hematite is soft, so that the rock crumbles readily under pressure. The sand grains shell out like corn,, and without much exaggeration the mill used for differential grinding might be called a "sheller,"

Jan 1, 1940

By Paul B. Harder

Round Mountain Gold (RMG) in cen­tral Nevada, reports that over a nine-year period and a million operating hours, its fleet of 150-ton and 190-ton haul trucks has averaged better than 93% availability, with some of the trucks approaching 70,000 operating hours. Repair costs have been far below industry averages. Mine operations manager Pete Kesl credits the high availability and low repair costs to a succession of Product Support Agreements between RMG and Caterpillar dealer Cashman Equipment. He adds that good equipment and a high level of trust and co­operation between all parties to these agreements have been essential to their success at Round Mountain.

Jan 1, 1998

Wires leading to or from underground facilities can develop hazardous voltages because of lightning exposure. The locations of many mine portals are particularly susceptible to lightning effects. The application of protective devices to limit this potential danger is necessary.

Jan 1, 1975

By T. J. Ballard

Corundum is a natural alumina (A120 ) and is next to the diamond in hardness . Except for the gem varieties , it is used principally as an abrasive , chiefly in grinding , dressing , and polishing metals and optical glass . Natural corundum is preferred to artificial abrasives for certain specialized jobs . Most of the corundum ( excluding emery ) mined in the United States came from the Corundum Hill mine in North Carolina and the Laurel Creek mine in Georgia . The Corundum Hill mine provided over half of the domestic production of corundum prior to 1900. Since 1900 , the importation of foreign corundum and the manufacture of artificial abrasives caused the decline of corundum mining in the United States .

Mar 1, 1947

By Ralph L. Brown

"IntroductionThe accumulation of gummy and resinous deposits in consumers' gas meters began to assume serious proportions about 1917. As the trouble developed and spread in the years following, it manifested itself in several ways, which ultimately began to the expressible in distinctly economic terms, more specifically in terms of costs; in 1922 an organized and fundamentally based investigation of this trouble was begun. In an earlier paper*** a short statement of the occurrence and costs of the deposition was given and at the same time an analysis of the problem, as well as well as a general plan of attack, was presented. That plan included two general phases, first, a chemical study of typical was 1 quarry or 2 cosinous content , mauformly consituents, rmln and selected subjects; and secondly, a comparative survey of plants affected and sufficient therewith, attention being paid to construction, operation, meter conditions and related data. In reporting progress in the axtual investigation, it was definitely set down that the basis of the gummy deposits was the unsaturated hydro consulting from the carburxtion of the water-gas with oil. That the presence of oily-gas condensate was closely associated with and largely"

Jul 1, 1923

By Jack C. White

As part of an investigation of the production of alumina by the nitric acid leaching of kaolinitic clay, the Bureau of Mines designed, built, and tested a fluidized-bed system for the calcination of aluminum nitrate nonahydrate to alumina, while recovering nitric acid. The calciner consisted of an 8-in-square by 36-in-tall vessel containing 18 in of fluidized solids. Molten aluminum nitrate, sprayed directly into the fluidized solids, formed sandy, granular alumina by growth of successive layers on fluidized particles. Solids were fluidized in a dense bed at temperatures of 250° to 500° C with steam, air, or mixtures thereof. Decomposition of nitrate ranged from 4 to 10 pet during single-pass steam or air fluidization, respectively. Alumina dust losses and low throughput are significant unsolved problem areas.

Jan 1, 1982

By Irving Hartmann

At the 9th International Conference of Directors of Safety in Mines Research a paper6/ was presented describing the initial phases of research by the Safety in Mines Research Establishment at Buxton, England, on the remote control of timber fires with high-expansion foam plugs in a rock tunnel. The work received extensive publicity, and great interest was aroused by the implied possibility that the method might be used successfully to control coal-mine fires, which for various reasons cannot be approached and attacked by standard fire fighting measures and frequently require sealing extensive, valuable coal properties and lead to loss of production and coal reserves and occasionally loss of lives. To investigate the practicability of the foam-plug technique under American min¬ing conditions, with room-and-pillar-type extraction and multiple entries, the Bureau of Mines in 1957 began an investigation at its Experimental Coal Mine, Bruceton, Pa, In preparation for this work it was necessary to rehabilitate and reinforce an elliptical tunnel in the mine where studies had been made, many years ago, leading to development of a ventilation system used in the Holland Tunnels between New York and New Jersey, and in many other vehicular tunnels.

Jan 1, 1958

By S. J. Broderick

[The term "nonmetallic minerals,? as commonly used in the mining industry, refers to those minerals of industrial importance that are mined essentially for uses other than for the metals contained. The field comprises several hundred minerals of industrial importance, of which 70 have been adequately described in the textbook Industrial Minerals and Rocks.3/ A few of the more important nonmetallic products are sand and gravel, salt, phosphates, clays, refractories, linestone, and cement materials. Some of tic minerals, such as bauxite and pyrolusite, have both metallic and nonmetal is applications, but in this report only the nonmetallic mineral phases are considered. In the organic field of nonraetallics only coal is considered, as, the, others - petroleum, natural gas, natural bitumens, and hydrocarbons - are of no importance in water softening.]

Jan 1, 1941

By Fred N. Kissell

Methane concentration peaks were measured by the Bureau of Mines at coal mine working faces during entry development. The statistical distribution of peaks was found to be normal or log normal depending on how well the methane was being mixed into the ventilation airstream. A normal distribution indicated good mixing, whereas a log-normal distribution indicated that mixing was poor. In addition, the "highest" peaks over selected intervals were found to fit a type I extreme-value distribution, a result similar to that obtained while mining longwall faces.

Jan 1, 1974

By P. E. Churchward

Rhenium sources and recovery methods were investigated by the Bureau of Mines to delineate potential resources of the metal. The only significant rhenium resource appears to be about 28,000 lb of rhenium contained in the domestic annual output of approximately 20,000 tons of byproduct molybdenite concentrates from porphyry copper operations. An estimated 70 to 80 pct of this rhenium is potentially recoverable by processing the rhenium-bearing fumes and dusts obtained during conventional roasting of molybdenite concentrate. At 70 pct recovery this would amount to 19,600 lb of rhenium. A more conservative estimate by the Committee on Refractory Metals of the National Research Council (1513 is that 12,000 lb of rhenium metal could be produced annually from current production of molybdenite from porphyry copper operations in the United States. A procedure was developed in the laboratory for recovering rhenium in the form of electrolytic flake by electrowinning the metal from a solvent extraction strip solution. The procedure included (1) water leaching of molybdenite roaster flue dust, (2) selective extraction of rhenium from the leach liquor by contacting it with a kerosine solution of a quaternary amine, (3) stripping of rhenium from the loaded organic solution by a perchloric acid solution, and (4) electrodeposition of rhenium from the loaded strip liquor. Raw material for the studies was flue dust containing 0.48 pct Re, 35 pct Mo, and 23 pct S in sulfide and sulfate form, and small amounts of numerous metallic impurities. Water leaching dissolved 85 pct of the Re and yielded a solution that was 13 in sulfuric acid and contained, 1 g/l Re and 16 g/l Mo. The solvent extraction strip solution that was electrolyzed for rhenium deposition was 1 molar in perchloric acid and 1 molar in ammonium sulfate and contained 13 g/l Re and 0.01 g/l Mo.

Jan 1, 1963

By H. W. Gillett, E. L. Mack

"This report describes the trend of developments in electric brass-furnace practice in the last two years, and supplements Bureau of Mines Bulletin 202, ""Electric Brass-Furnace Practice"", which was published in 1922. In that bulletin it -as pointed out that some of the lines on which electric brass-furnace progress would take place were clear, but others were less so.Developments in foreign countries.Foreign brass-melters have not yet adopted electric melting to an extent comparable to its use in the United States. It is doubtful Whether all foreign countries combined use 100 electric brass furnaces; of these about 35 are of American make (Ajax, Detroit, Baily) and are operating in Canada, Mexico, England, France, Japan, Sweden, Switzerland, Spain, Norway, Germany, Argentina and Czecho-Slovakia.`The Rennerfelt furnace finds some use in Sweden (1)c, notwithstanding its high metal loss on alloys high in zinc, Two German firms are reported(2) to be using the Rochling-Rodenhauser induction furnace on bronze, the average energy consumption being given as 400 kw.-h. per ton. No comment is made on any trouble from the ""pinch effect"", A firm in Switzerland is reported (3) to use three 600-lb., direct-arc furnaces of its own design to melt babbitt, antimonial lead, coinage silver, nickel, copper, and brass. The metal loss on yellow-brass turnings is high. Use Of a direct-arc furnace in England, with precautions aimed to prevent surface overheating, vas abandoned (4) in favor of an Ajax furnace."

Apr 1, 1924

By Ted C. Briggs

Twenty-two compressibility runs were made with helium over the temperature range -5° to 80° C and at pressures to 800 atmospheres. A Burnett apparatus was used. Data from the runs were fitted to a fourth degree polynomial equation of state in the pressure and a weighting factor of Pr-3/4 was used. All data for a particular isotherm were treated simultaneously. A temperature function was found to represent the parameters B and C. Compressibility factors determined by this investigation are believed to be accurate to better than 0.05 percent.

Jan 1, 1970

By D. H. Chambers

Digestion studies were undertaken to develop a method for the rapid dissolution of high-temperature ferroalloy scrap. Laboratory tests showed: (1) dissolution of alloy scrap with ferric ion as the leaching agent was a moderately rapid method of digestion; (2) the dissolution process can be considered as a typical reaction of a metal with chlorine gas, although evidence was obtained to show dissolution as a two-step process, one step as the reduction of ferric ion by the soluble alloy constituents and the other as the oxidation of ferrous ion with chlorine gas; and (3) the attack of ferric ion on the alloy was a function of alloy composition, ferric to ferrous ion ratio, and area of contact between leach solution and alloy. The exceedingly complex nature of alloy compositions and dissolution products generally precluded satisfactory analytical determinations. Results of moderate accuracy were obtained using complex modifications of standard analytical and spectrographic techniques.

Jan 1, 1968

By D. W. Bridges, S. R. Borrowman

Thorium and yttrium oxides were recovered from siliceous ores of the Powderhorn , Colo . , area . Processing comprised ( 1 ) acid curing and subsequent ( 2 ) acid baking , ( 3 ) leaching , and ( 4) solvent extraction of thorium , using a primary alkylamine , and yttrium , using di - 2 - ethylhexyl phosphoric acid . About 95 pct of the contained thorium and yttrium was recovered from ore containing 1.2 pct Th02 and 0.5 pct Y₂ 03. The thoria product was 99 pct Tho ; the yttria product was 77 pct Y₂ 03. A 150 - to - 1 concentration ratio was effected on the latter , but some contaminating lanthanon - group oxides remained .

Jan 1, 1964

By Hugh Haddow

This paper describing the methods of recovery and treatment of a sand and gravel deposit and the preparation of these materials for a number of special markets is one of a series being prepared by the U. S. Bureau of Mines. It is of particular interest to those sand and gravel operators who have a surplus of fine sand which must be sent to waste, both from the point of view of, equipment and the variety. of markets supplied, and in that it describes one of the few sand and gravel plants which have resorted to hydraulic classification for sizing fine sand. ACKNOWLEDGMENTS The author wishes to acknowledge the assistance of J. R. Thoenen, mining engineer of the Bureau of Mines, in the preparation of this paper.

Jan 1, 1931

By M. C. McCall

When electric current of any appreciable magnitude flows from a power line into the earth, a change sometimes takes place in the conditions of resistivity immediately surrounding the electrode or medium of contact. If the conducting medium is composed of moist earth or clay the effect is to increase rapidly the resistance. If the conducting medium is coal or a coal bed, the effect is one of slowly decreasing resistance as the coal is carbonized, If, however, the flow of current is not enough to carbonize the coal, it will dry slowly, with a resultant increase in resistance. Measuring ground resistance, or impedance, with conventional commercial ground testers does not always indicate the current that will flow in the earth circuit from a direct-current or an alternating-current power circuit. The exact reason for this has not been determined however, it is thought to be due to the comparatively minute currents used for such testing. A typical ground, tester used by the authors for this work indicated a maximum current of 25 milli-amperes. The frequency of this testing current also has an effect on the readings in all probability. While the possibilities of the effects of varying frequencies has by no means been fully explored in this investigation, there are very definite indications that the impedance of a circuit through a section of earth will vary in some inverse relationship to the frequency of the applied voltages. This is evident at ordinary power-line frequencies ns well as at higher frequencies up to 200 kilocycles, which was the highest frequency available for tests in this investigation. This report is written in the hope that it will stimulate further investigation of the possibilities suggested for communication and the development of safety devices for increased electrical safety in coal mining.

Jan 1, 1952