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By Douglas C. Corner

This is the first of a series of papers dealing with modern tunnel-driving methods, compiled in accordance with an outline prepared by engineers of the United States Bureau of Mines and to be published in a series of information circulars by the bureau. This series will supplement a similar and earlier series of papers dealing with mining methods and costs. ACKNOWLEDGMENTS The author desires to express hiss appreciation, of the assistance of A. C. Dennis, manager for the West Construction Co. Contractors, and Franc: E. Winsor, chief engineer for the Boston Metropolitan District mater Supply Commission who furnished much of the data and detailed description of operation appearing in the following pages. C. F, Jackson, mining engineer, United States Bureau of Mines, collaborated in the preparation and arrangement of the text.

Jan 1, 1931

By S. J. Aresco

The Bureau of Mines has been active in promoting the purchase of coal for Government use under specifications that define the requirements in terms of heating value of the coal, expressed in British thermal units, and the composition as shown by proximate analyses. To these, when required, are added the ash-softening temperature, the free-swelling index, and the Hardgrove grindability index. Under most of these specification contracts the bidders guarantee the quality of the coal, and that guaranteed by the successful bidder becomes the standard of his contract. The deliveries are sampled in accordance with instructions3 issued by the Bureau of Mines; the samples are analyzed in the Bureau laboratory to determine whether the coal is of the quality guaranteed by the contractor; if it is not, a price adjustment is made. Analyses of the delivered coal and tipple samples (samples collected at mine tipples as coal is being loaded into railroad cars or trucks) provide valuable data for use in evaluating future bids. In addition, the continuous sampling of coal as delivered is a check on the practical results obtained in burning the coal.

Jan 1, 1968

By George A. Bell

This paper reviewing the leaching practice of the New Cornelia mines of the Calumet & Arizona Mining Co. at Ajo, Ariz., is the first of a series being prepared by the Bureau of Mines on leaching methods and costs in the various mining districts. ACKNOWLEDGMENTS The author acknowledges the assistance of T. G. Chapman, consulting engineer, and E. D. Gardner, supervising engineer of the Southwest Experiment Station, Bureau of Mines, Tucson, Ariz.

Jan 1, 1930

By J. B. Janus

This report continues a series of analyses of coal samples made by the Bureau of Mines in connection with the yearly purchase of several million tons of coal for various Government agencies. Listed are the analytical data on the composition and quality of tipple and de livered samples of coal collected during fiscal year 1974.

Jan 1, 1975

By Bryan Buchholz, N. Kumar Kittusamy

Previous studies indicate that operators of heavy construction equipment are afflicted by musculoskeletal injuries of the arms, shoulders, neck, and lower back. These injuries appear to be due to excessive periods of sitting (static posture), work intensity, whole-body vibration, high resistance levers, repetitive motions, and awkward postures. (2-5) Although numerous studies have shown an association between operation of heavy construction equipment and symptoms of musculoskeletal disorders, very little research has been performed that systematically characterizes operating engineers' exposure to ergonomic hazards. The objective of this study was to systematically characterize the ergonomic hazards associated with excavating operations. As such, the following were performed: (1) vibrations were measured at the operator/seat interface (X, Y, and Z axes), and at the floor of the cab (Z axis); (2) psychophysical ratings of whole-body vibration (WBV) level and overall seat design were obtained; and (3) postural assessments of the job were made. Methodology This study evaluated an inexperienced female operator performing excavation, utilizing two different pieces of equipment. The operator was 37 years old, 162 cm tall, and weighed 80 kg. She had approximately 15 hours of operation time (experience) on the equipment evaluated. The two pieces of equipment used were: a Case Super 580E (1986) backhoe/loader, and an Insley H-2000 excavator (1975) (see Figures 1 and 2). More evaluations were performed on the backhoe/loader than on the excavator. The following evaluations were performed on the Case equipment: 1) vibration levels at the seat and floor; 2) psychophysical ratings of the overall seat design and vibration levels (for the task duration, and for an 8 hour duration); and 3) postural assessments. For the Insley equipment, all of the evaluations were performed except vibration measurements. When the evaluations were conducted, the following environmental conditions were noted: the temperature was 31°F, and soil and terrain conditions were rough and frozen.

By N. A. Gokcen

This Bureau of Mines report reviews and summarizes recent studies of the rates of chlorination of aluminous resources with CO and C12 mixtures with and without COC12. No reaction mechanism could be obtained from the existing results; however, diffusional barriers in the gas and solid layers probably control the chlorination rate in thermogravimetric experiments. Fluidized beds of particles smaller than 0.1 mm appeared to show very little solid layer diffusional barrier. For optimum chlorination the particle size should probably be less than 8 mm, the calcination temperature approximately 700° C, and the chlorination temperature from 650° to 750° C. Relatively rapid chlorination with COC12 in thermogravimetric experiments was attributed partly to the simultaneous supply of reductant and chlorinator by one gas to the sample reaction site. Comparable results for chlorination of fluidized beds with COC12 are not available. Equimolar mixtures of CO and C12 produced the optimum rate of reaction. Addition to the calcine of 10 to 20 wt-pct NaCl accelerated the rate of chlorination, and addition of SiC14 to the gas mixture decreased the rate of chlorination of SiO2 drastically, but at the expense of chlorination of significant fractions of Al2O3. Further research in various areas is suggested.

Jan 1, 1983

By Joseph Blake Smith

Coal resource data from published sources and company files were used by the Bureau of Mines to determine the location and extent of strippable coal reserves in Wyoming. Total strippable reserves of 23 billion tons were estimated in seven major coal areas. Seven large strip mining operations were active in 1969, and their production totaled 45 million tons of coal. Cutoffs used to define strippable reserves were (1) minimum coalbed thicknesses of 5 feet; (2) overburden-to-coal ratios of less than 10 cubic yards of over- burden per ton of coal; and (3) total overburden thicknesses of less than 120 feet, except where reserves occur in multiple beds or a single thick bed. Tertiary rocks along margins of the Powder River basin contain most of the strippable coal reserves in Wyoming. The Wyodak beds, ranging in combined thickness from 30 to 1.30 feet, crop out on the east flank of the basin and contain an estimated 19 billion tons of strippable subbituminous C-rank coals under less than 200 feet of overburden. Partings between these beds total less than 60 feet. The 100- to 200-foot-thick. Healy bed on the western flank of the basin and the 35-foot-thick School and 20-foot-thick Badger beds on the south also contain large strippable reserves. Elsewhere in Wyoming, strippable reserves. Elsewhere in Wyoming, strippable deposits are subbituminous coal of Late Cretaceous and Tertiary ages, mostly in the Hanna and Great Divide basins in the south-central portion of the State and in the Kemmerer-Hamms Fork region in the southwestern corner.

Jan 1, 1972

By S. P. Holt

The Salt Chuck mine is on the east bank of the Salt Chuck, a salt-water inlet at the head of Kasaan Bay, Prince Edward Island, Southeestern Alaska. The deposit was worked at intervals from 1905 until. 1941. Early ship-ments of hand-sorted ore are reported to have assayed about 4 percent copper, 0.15 ounce gold, and 0.15 ounce silver. The total mine production up to 1941 is reported to have been 326,000 tons containing 6,200,000 pounds of copper. During December 1942 the Bureau of Mines cut a 15-foot channel sample on the surface and channel samples from headings on the 300-foot level. In July 1943 a development project was started. Thirteen diamond-drill holes totaling 1,550 linear feet were drilled from underground stations on the 200- foot and 300-foot levels.

Jan 1, 1948

By F. C. Gibson

An electrical method for the continuous determination of propagation velocities in opaque, confined explosives, and propellants is described. A resistance element imbedded in the reactive material generates electrical signals that are displayed oscillographically and indicate the position and progress of a reactive zone associated with progress of a reactive zone associated with burning or detonation. The method is applicable to both solids and liquids.

Jan 1, 1963

By N. A. Gokcen

In this Bureau of Mines report, appropriate equations correlating the activity of water with the activities of electrolytes in binary and multicomponent solutions have been derived for computer calculation. It was found that the half-integer power series are far superior to the integer power series, for both types of series having the same number of terms. The pro-posed method of calculation is capable of accurately yielding the activities of all components from the measurements of the activity of a single component at various concentrations. This method replaces the cumbersome and objection-able method of graphical integration of the Gibbs-Duhem equation. Two novel methods are proposed for determination of activities of electrolyte solutions important in hydrometallurgy; (1) Water vapor pressure measurement by differential pressure transducers having an accuracy of 0.001 pet, and (2) transpiration method with an inert gas bubbled through concentrated solutions followed by the analysis of the evaporated and redissolved electrolytes with specific ion electrodes having a sensitivity of ±10-10 molal. The first method is suitable for nonvolatile electrolytes, and the second, for volatile electrolytes such as hydrogen halides, HN03, H2S03, etc. The existing methods of estimation of ionic activities have been surveyed, and the best method has been selected, discussed, and summarized.

Jan 1, 1979

By Edward F. Divers

This Bureau of Mines report describes a new type of scrubber (dust collector) and ventilation system built into the auger support frame (boom) of a Jeffrey 120L continuous mining machine. With this twin scrubber arrangement, one scrubber is mounted into each side of the boom. Each scrubber includes a 2,500-cfm fan, a flooded fibrous-bed scrubber panel, and a water droplet eliminator. The system was designed for minimum size and adds only a few inches to machine height. Exhaust duct design allows flexibility with various airflow configurations to suit both blowing and exhaust fare ventilation systems and brattice distances ranging up to 20 feet. Full-scale tests with exhaust ventilation were conducted at a Mine Safety and Health Administration surface facility at Bruceton, Pa., to determine the scrubbers' methane dilution capability. Several configurations of the twin scrubber-ventilation system produced striking improvements in face methane dilution when compared with conventional systems.

Jan 1, 1981

By A. J. Kraemer

This report on the physical and chemical properties of typical crude oils of California is the eighth in a series which will cover the producing districts of the United States, and is supplementary to Serial 2595 of the Bureau of Mines, which includes discussion of results, summary tables, and selected typical analyses of California crudes. The present report contains additional individual analyses of crude, oils from the fields of Fresno, Kern, Los Angeles, Orange, and Ventura Counties.

Jan 1, 1924

By Mark Sheppard

[Considerable research work hi been done on secondary crushing and coarse and fine grinding, and the literature on the general subject of Crushing contains many references to the work of investigators on the laws governing end the factors entering into the economical production of fine materials. However, little information on primary crushing in available The literature deals mainly with problems and practices in ore dressing, end in this field the engineer or investigator is concerned largely with the production of fine material and the unlocking of minerals in the ore. Under such conditions close control of screen sizes of primary-crusher products is a secondary consideration and has received very little attention.]

Jan 1, 1938

By A. W. Fahrenwald

"About two years ago the Bureau of Mines, Department of the Interior, and the University of Idaho undertook an investigation of classification in its relation to table concentration of Idaho ores. The cooperation of the management of the Bunker Hill & Sullivan Co. in placing at our disposal their West Mill and facilities as desired, offered an unusual opportunity for studying the field of hindered classification in its practical and economic relation to table concentration.It has been shorn theoretically, and demonstrated experimentally, that ore products are more easily and economically concentrated on tables if the natural feed, consisting of various minerals and of all sizes of particles of each mineral, be classified or grouped into a series of products in which the mineral particles of greatest density are small in diameter relative to the diameter of the mineral particles of lesser density. Products in which the maximum difference in diameter of light and heavy minerals occurs are to be obtained only by true hindered settling classification. To our knowledge there has never been a really good hindered settling classifier used in practice and the present tendency seems to be to by-pass any attempt at such classification.After a careful study of the nature of hindered classification and of the requirements for hindered settling in practice, a classifier has been developed that takes fullest practical advantage of the widely known, but generally only meagerly understood, condition of hindered settling so well analyzed a number of years ago by Dr. Richards.The present paper presents briefly some of the more important practical results accruing through the investigation."

Jun 1, 1924

By Oliver Bowles

"Properties and Uses.Iceland spar is a name given to a pure crystallized form of calcite (CaCo3) which is sufficiently transparent and free of defects to be used in the manufacture of optical instruments. While the actual requirements are small, the degree of purity and physical perfection demanded renders it somewhat difficult to obtain suitable material.The properties of value in Iceland spar are its transparency combined with double refraction. It is used in the manufacture of polarizing microscopes, saccharimeters, colorimeters and photometers. Its most important use is in the manufacture of Nicol prisms, which constitute an essential part of every polarizing microscope. The principle governing the construction of the Nicol prism is as follows:Ordinary light in passing through a crystal of calcite is resolved into two rays of plane polarized light vibrating in planes at right angles to each other and having different indices of refraction. Thus the two rays follow different paths through the crystal. The prism of Iceland spar is cut diagonally and cemented together again with a transparent cement having an index of refraction intermediate between the two rays passing through the prism. Canada balsam is employed for this purpose. The prism is cut at such an angle that the ray having the greatest index of refraction meets the surface of the balsam at an angle greater than the angle of total reflection, and it is thus deflected to the side of the prism, while the second ray passes through. Thus one of the rays is eliminated and polarized light vibrating in a single plane is obtained."

Apr 1, 1920

By N. S. Dalal, Xianglin Shi

"Electron spin resonance (ESR) measurements provide direct evidence for the involvement of Cr(V) in the reduction of Cr(VI)· by NAD(P)H. Addition of hydrogen peroxide (H2 O 2) to NAD(P)H-Cr(VI) reaction mixtures suppresses the Cr(V) signal and generates hydroxyl (·OH) radicals (as detected via spin trapping), suggesting that Cr(V) reacts with H2O 2 to generate the ·OH radicals. Reaction between H2O 2 and a Cr(V)·glutathione complex, and between H2O 2 and several Cr(V)-carboxylato complexes also produces ·OH radicals. These results suggest that Cr(V) complexes catalyze the generation of ·OH radicals from H2O 2, and that ·OH radicals might play a significant role in the mechanism of Cr(VI) cytotoxicity. KEY WORDS: ESR. spin trapping, Cr(VI) reduction, Cr(V), hydrogen peroxide, free radicals.INTRODUCTIONThis communication reports an ESR spin trapping detection of hydroxyl ( OH) radicals.in reactions between some Cr(V) complexes containing biologically important ligands and hydrogen peroxide (H2O 2 ). This work was undertaken because while the reduction of Cr(VI) to lower oxidation states has been suggested as a key step in the mechanism of Cr(VI) toxicity, the reaction· mechanism is not yet clear. 1 Mutagencity has been well documented for Cr(VI) via various bacterial assays, while Cr(III) has been shown not to be mutagenic.2 • 3 Since it has been reported that compounds containing Cr(VI) do not react with isolated DNA,4 the reduction of Cr(VI) by other cellular constituents has been thought to be important in the mechanism of Cr(VI) induced DNA alteration.1·4 • 5 For cellular systems earlier studies include those on the reduction of C~(VI) by microsomes,6-8 rat liver DT-diaphorase,9 and aldehyde oxidase. 10 Regarding the reduction mechanism, Jennette used ESR spectroscopy to show that a long-lived Cr(V) complex is formed as an intermediate in the microsomal reduction of Cr(VI) in the presence of NADPH.8 She postulated that Cr(V) is the ""ultimate"" carcinogenic form of chromium compounds. This conclusion has led to many further investigations of the formation of Cr(V) in the reduction of Cr(VI) under biologically relevant conditions.11 - 19 More recently, however, it has been suggested that oxygen-derived radicals generated during the Cr(VI) reduction are the species responsible for the DNA alteration.20.2• To the best of our knowledge, however, no information is available on the generation of such radicals in the reduction of Cr(VI) under biologically relevant conditions, except some preliminary results on the glutathionyl (GS·) radical formation in the reduction of Cr(VI) by glutathione (GSH). 11 - 19 We, therefore, undertook a systematic investigation of the reaction of Cr(VI) with NAD(P)H, GSH, ix-hydroxycarboxylic acids, and H2O 2 • NADPH was chosen as a model reductant because of its ubiquitous existence inside the cells, its critical role in the enzymatic Cr(VI) reduction,1·6-9 its representation of important cellular Cr(VI) reductants, and its ability to reduce other metal ions.22 GSH was chosen as another model Cr(VI) reductant because GSH also exists inside cells, it represents another important category of cellular Cr(VI) reductants, the thiols, and it also plays an important role in the Cr(VI) toxicity .1• 1 ""- 19.i3.i4 For further clarification, we also studied the reaction of Cr(VI) with several '1'.-hydroxycarboxylic acids in the presence of H2O 2 since these acids are definitively known to reduce Cr(VJ) to form stable, isolable Cr(V).25 .2 6 The results obtained indicate that Cr(V) complexes, produced in the reduction of Cr(VJ) by cellular reductants, react with H2 O 2 to generate ·OH radicals, which might be the initiators of primary events in Cr(VI) carcinogenicity."

Jan 1, 1990

By E. D. Gardner

"A fire hazard exists in nearly all mines. Progressive mining companies recognize this danger and take all possible precautions to prevent any conflagrations, but in spite of such safety measures, mine fires do occasionally occur and endanger life and property. In order to be prepared for such an emergency, miners are trained in the use of self-contained breathing apparatus and the necessary fire-fighting equipment is kept on hand. Men trained to wear breathing apparatus can penetrate workings full of poisonous fumes, but in order to successfully combat fumes or to rescue miners, the rescue crews must be trained in fire-fighting operations and know how to proceed with a minimum loss of time when they get to the scene of action.In order to perfect fire-fighting plans and to train men of the Globe-Miami district under conditions approximating those found at an actual mine fire, mine-reseue maneuvers were held at Globe, Arizona, on October 17-20, inclusive. The work was done under the direction of Orr Woodburn, director, and his associates of the Globe-Miami District Mine Rescue and First Aid Association. He was assisted by Albert Tallon, safety engineer, and Herbert Finnegan of the Old Dominion Co.; Herbert Hodson, safety engineer for the Inspiration Consolidated Copper Co.; A. 3. Martinson and J. M. Harrington of Car One, and F. D. Gardner of the Southwest Station, Bureau of Mines. Invitations were issued to mining men likely to be interested and representatives of mining companies from other districts were present and observed the work.The Globe-Miami District Mine Rescue and First Aid Association is maintained by the mining companies in the district and each company contributes to the organization's support in proportion to the total number of men on the pay roll. A central station*, between Globe and Miami, has been established and a truck with 10 sets of 2-hour self-contained breathing apparatus and the necessary accessories is always in readiness to respond to a call to any of the mines in the district. Besides being in readiness for emergency work, the station employees train men in the use of mine-rescue apparatus and in first-aid to the injured at the mines of the association. The Globe-Miami Mine Rescue organization has been developed to high point of, efficiency under Mr. Woodburn's direction and is one of the best in the country. The three largest mines of the district such maintain a crew of 15 men trained in the use of breathing apparatus, and other mines keep crews of 5 men each."

May 1, 1923

By R. W. Hiteshue, C. O. Hawk, H. H. Ginsberg, M. D. Schlesinger

The Bureau of Mines studied single - step catalytic vapor - phase hydrogenation of oils derived from coal and oil shale . Treatment of middle oil , from hydrogenation of bituminous coal , gave good yields of gasoline with a German - made molybdenum- zinc - chromium catalyst . The Bureau also achieved good results with duplicates of this catalyst made from domestic raw materials . In one set of experiments with the German catalyst , 38 to 52 wt pct of feed was converted to gasoline . The total liquid product was 91 to 98 wt pct of the feed . Not all this gasoline can be claimed as production , however , because about 20 pct of the feed was in the gasoline range , and part of it undoubtedly survived the hydrocracking treatment . Hydrogenation of crude shale oil in the presence of cobalt molybdate catalyst produced a total liquid product of 89 wt pct of feed . The hydrogenation converted 27 wt pct of feed to gasoline and 44 wt pct of feed to diesel fuel . The remaining liquid product , 18 wt pct of feed , was residue boiling above diesel fuel . The gasoline was of poor quality , with an octane number of 39.1 . The overall product seemed a suitable feed stock for a conventional refining operation . Coker distillate hydrogenation , using a cobalt molybdate catalyst , gave a total liquid product of 97 vol pct of feed ; of this product 60 vol pct was jet fuel and 40 vol pct was diesel fuel . High nitrogen and sulfur in all three of these raw materials severely poison the usual refining catalysts . Thus , the common objective in these

Jan 1, 1964

By J. E. Crawshaw

"The few previous observations of the effect of turbulence on limits of inflammability have been made on a small scale in turbulence produced either by a fan or by movement of the mixture.By a suitable amount of turbulence from a fan the lower limit of methane was 5 per cent as compared with 5 per cent observed for quiescent mixtures in the same vessel.3 With a streaming movement of the gas mixture within the range of speed from 35 to 65 centimeters per second (69 to 128 feet a minute) the lower limit was approximately 5 percent,4 For a quiescent mixture of ethane the lower limit was 3.10 per cent ethane, but with fan running at a moderate speed a 3 per cent mixture exploded.5The object of the tests herein reported was (1) to determine the lower limit of natural gas in a mixture of natural gas and air Which would be ignited and propagate violently when the turbulence was produced by explosives fired from a cannon into the mixture; (2) to observe the behavior when the mixture contained less than this low limit; and (3) to determine how turbulence produced by a fan affects thin limit.Four series of tests were run, three of which were to determine the effect of different sources of ignition: Tests with (1) an electric igniter; (2) 3F black blasting powder stemmed with 2 pounds of dry fire clay stemming used to ignite the mixture, and (3) 40 per cent straight nitroglycerin dynamite unstemmed. The fourth was made to study the effect of turbulence produced by a two-speed electric fan, using an electric igniter as the source of ignition.In both series of tests with explosives, charges of 50 and 200 were used to determine the effect of increased quantity of explosives on the lower limit of natural gas."

Jul 1, 1930

By Charles Prasky

The Bureau of Mines investigated the conversion of nonmagnetic iron minerals to magnetic form through reduction Toasting operations. The primary objective was to obtain a concentrate that could be used as a direct shipping material for blast furnace consumption. Crude iron materials from the Steep Rock Lakes, Ontario, area were prepared into a blend of 8 parts siliceous ore, 3 parts pyritic ore, and 1 part tailings. Experimental work included laboratory reduction roasting tests, two continuous 10-day campaigns, and one 12-hour test all in a 34-inch by 36¬-foot rotary kiln. The objective of the project was achieved in producing an iron concentrate containing about 66 percent iron with over 90 percent iron recovery. Desirable operating conditions were developed in the kiln but optimum process variables were not completely established.

Jan 1, 1969