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By D. Harrington, R. R. Sayers

For several years the writers have been studying various phases of the effect of air conditions in metal mines upon underground workers ; in 1918 a short study was made in certain hot and deep mines and brief reports were issued in the Engineering and Mining Journal ( August , 1920) and in the U. S. Public Health Reports (Vol . 36 , No. 4 , January 28 , 1921 ) . In 1921 a more extended study was made (also in hot and deep metel mines ) with intent to determine the limiting conditions imposed upon underground workers by the physiological effect of various air movements , temperatures , and humidities , with and without work . It is the purpose to publish a series of short papers on this later investigation , each paper to consider one particular phase of the work . The present paper deals with the effect on body temperature and pulse rate in still air as compared with moving air of temperatures from 90 to 100° F . and 100 per cent relative humidity, the subjects at rest .

Apr 1, 1923

By R. M. Santmyers

Caesium, rubidium, and lithium are sometimes described as the minor or rarer alkali metals. They generally occur together in nature, although, lithium is distributed more widely and is far more abundant than either of the other two. The chemical, and even the physical, properties of these three elements can best be considered In conjunction with the more familiar members of the alkali group, sodium and potassium. The five elements lithium, sodium, potassium, rubidium, and caesium show an interesting gradation properties from member to member with the increase in atomic weights. All are silvery white and soft enough to be cut with a knife. They tarnish rapidly in air and decompose water at ordinary temperatures. The lowest temperature at which the action of the several metals on water can be de¬tected is -98°C. for sodium, -105°C, for potassium, 108°C. for rubidium, and -116°C. for caesium. The chemical activity appears to increase steadily from

Jan 1, 1930

By James A. Browning

Following an unsuccessful attempt earlier in the program to develop and market a drill channelling machine, we have designed and tested a new continuous channelling method which reduces operating sound levels to below 100 db. This new method relies on a small diameter oxygen-enriched burner to produce narrow channels. Sound intensities are reduced substantially compared to conventional channel widths. They are further reduced by a water spray directed immediately above the flame. Baffles placed along the top of the channel will reduce sound levels to below 90 db. Cutting rates are greater than those of existing channelling burners with costs per unit of channel area substantially reduced for those cases where oxygen costs are reasonable.

Jan 1, 1981

By K. Biswas, S. Iverson, S. J. Jung

Computer modeling of rock flow in ore passes is being investigated and compared using MSC Soft-ware’s Working Model 2D1 (WM2D) and Itasca Corp.’s Particle Flow Code in Two Dimensions (PFC2D). This work is being carried out by the Spokane Research Laboratory of the National Institute for Occupational Safety and Health to determine the usefulness of computer modeling to improve ore pass design. The types of tests included pendulum tests to validate WM2D simulations and simulated single-rock drop tests in both WM2D and PFC2D to understand their contact models. Simulated rock impacts at the ore pass chute and the use of inclined ore passes and doglegs were investigated in both programs. A PFC2D simulation showed that dynamic loads at the chute gate were reduced significantly when a dogleg transition was used, and simulations in which the ore pass was inclined showed significant reductions in chute impact loads compared to simulations of a vertical ore pass. A released hang-up was simulated using PFC2D.

By A. W. Fahrenwald

The logic leading to the development of the experiments in this paper already has been stated in Part I,3 but is briefly as follows: The results of the batch-grind experiments in which time of "grind" and fineness of finished product were the variables, strongly indicated (1) that batch grinding involving a single grind could not be operated under any condition to give maximum mill efficiency, (2) that the, sieve analysis of the feed charge in the mill materially affected the efficiency of the mill, and (3) that the percentage of finished product in the mill is a vital factor in ball-mill efficiency. A laboratory closed-circuit grind technic designed to simulate present closed-circuit grinding suggested itself, in which: a ball mill and a classifier constitute the grinding unit. The features of the closed-circuit grinding system are: (1) Short large diameter mills, (3) rapid flow of pulp through the mill, (3) continuous automatic removal of finished product from the system, and (4) high circulating loads. The high circulating load is a result if the short length of the Mill - that is, of the time the charge remains in the mill - and the small percentage of finished material produced during each circuit of the feed through the mill.

Jan 1, 1930

By P. C. Good

The Bureau of Mines conducted a laboratory investigation of a sinter-leach method to recover aluminum and fluorine from waste carbon potlining residues from secondary cryolite recovery operations in aluminum reduction plants. After removal of carbon by burning, the residue was sintered at 900° to 1,100° C with silica and N2CO3, then crushed and leached with dilute NaOH solution, dilute Na2C03 solution, water, or water containing residual Na2O which remained in the sinter after reaction and decomposition of Na2CO3. Over 90 percent of the contained aluminum and up to 87 percent of the contained fluorine were extracted from this waste product in the form of a mixed alkaline solution. Treatment of the alkaline solution with CO2 yielded a white precipitate containing 89 percent of the original aluminum and 61 percent of the original fluorine as a mixture of synthetic cryolite and alumina, together with a variable excess of soda.

Jan 1, 1969

By Sidney Katell

An estimated capital investment of $76,499,800 will be required for a plant designed and built to produce 90 million standard cubic feet per day (std.c.f.d.) of synthetic pipeline gas through Lurgi gasification of bituminous char. This investment figure does not include the pretreatment plant, the cost of which is assumed to be reflected in the cost of the char fed to the gasification system. Shift conversion, C02 removal, and methanation are required after gasification in the Lurgi unit to make a gas suitable for pipeline transmission. Capital investment data are based upon equipment costs, January 1959. Based on a 90-percent or 330-day operating year, the operating cost before profit and Federal taxes with the char price as a variable will amount to the following: [ ]

Jan 1, 1959

By GEORGE S. POPE

The purchase of coal by the Government under specifications depending on the heating value of the coal, its content of ash and of moisture, and other considerations, rather than upon the reputation or trade name of the coal, was based on the fuel investigations begun by the Technologic Branch of the United States Geological Survey in 1904. The plan was first adopted by the Treasury Department in 1906. Since then the plan, variously modified in form but the same in principle, has been gradually adopted by other departments until at present of the coal used by the Government, the total value of which approximates $8,000,000 annually, more than half is purchased under specifications. The Government publications dealing with the adoption by the Government of the specification plan, the number of contracts awarded on that basis, and the quality of the coal delivered under such contracts in the several fiscal years covered by the reports are given in publications listed at the end of this bulletin. Under the authority of acts of Congress making appropriations for analyzing and testing fuels belonging to or for the use of the United States Government, a laboratory is maintained at the headquarters of the Bureau of Mines, Washington, D. C., where samples represent- ing deliveries of coal purchased under specifications for Government use are analyzed and tested. At this laboratory more than 1,200 samples have been analyzed and tested in one month. With the complete equipment and the efficient force employed, the analytical work has been so perfected that the analyses and heating-value tests of the samples received are as accurate as may be reasonably expected in laboratory work of this nature. One of the serious drawbacks to the general adoption of the speci- fication method for the purchase of coal is the difficulty of obtaining at reasonable cost samples of coal that can be considered fairly repre- sentative of the commercial product delivered in wagons, railroad

Jan 1, 1913

By O. W. Owings

"The handling and transportation of explosives and explosives supplies are inherently hazardous owing to their sensitiveness to impact and flame or electric arcs and sparks. Many accidents have occurred in the past during transportation of explosives, especially when they were carried by individual miners on man-trips. When electric haulage became the usual mode of transportation and shots were fired electrically, the hazards of carrying explosives and supplies on man-trips were fully realized, and in some mines all explosives were placed in one car, usually at the rear of the trip. Far-sighted managers saw the danger of this practice and provided separate trips for delivering explosives. This step was a definite advance in safety, but the latest achievement is the construction of special, rugged, nonconducting cars.Many coal-mining men have shown considerable interest in the construction of safe cars for explosives during recent months. Undoubtedly many others are interested in this phase of safety, therefore this circular is issued to give information on cars of this type now in use.Car A (fig. 1) is essentially a closed inner box separated from an outer box by an insulating lining of rubber. The double box is attached to a standard steel chassis that has spring journals and electric welding instead of certain rivets. The chassis is equipped with roller bearings. The over-all length from pin to pin is 11 feet, 9 inches; the wheel base is 54 inches, the track gage 42 inches, and the capacity eighteen 50-pound cases of permissible explosives. The box is 10 feet long, 6 feet wide, 3 feet high at the top of the arched roof, and 2 feet 9 inches at the edges. The top of the car is 46 inches above the top of the rail.The inner box is insulated from the outer box by two pieces of 1/4-inch switchboard.-insulating matting cemented together. To cover the top, two ends, two sides, and the bottom of the box requires 320 square feet of the l/4- inch matting.The walls are well-seasoned tongue-and-groove oak, 1 1/4 inches thick and 2 3/4 inches wide. A 1 1/4-inch air space is maintained by oak strips between the outer wall and the two thicknesses of 1/4-inch rubber matting. The inner box is made of 7/8-inch, well-seasoned, tongue-and groove oak fitted closely against the insulating matting. No nail, rivet, or bolt extends through the rubber insulation.The floor of the outer box is secured to the chassis by two sets of bolts through an intermediate piece of well-seasoned oak. One set of bolts is countersunk from the top of the intermediate piece of oak, and the other set is countersunk from the bottom. The countersunk portions are filled with ""insulate,"" an insulating compound. Adjacent bolts are at least 6 inches apart.The bed of the inner box is divided into six compartments by transverse strips of wood at the bottom and partitions near the roof. Each compartment accommodates three 50-pound cases of explosives. This arrangement prevents cases in adjacent compartments from touching, so that there is no possibility of end thrust of the entire load of explosives. Each inner compartment is 21 inches high, 5g inches long, and 16 1/4 inches wide. Separating strips at the floor are 3 inches wide and 1 1/4 inches thick. The outside dimensions of the 50-pound cases of explosives used are 17 1/2 inches long, 13 1/2 inches wide, and 12 1/2 inches high."

May 1, 1940

By D. J. Singleton

Erosion corrosion of 12 alloys in phosphoric acid waste water was studied by the Bureau of Mines. Tests were conducted on oblate spheroids or cylindrical specimens in 12-and 60-cm-diam ball mills by grinding phosphate rock in gypsum pond water with a starting pH of 1.6. For comparison, tests were conducted while grinding phosphate rock in plain water. Static corrosion tests in gypsum pond water also were conducted. For all alloys, the wear by erosion-corrosion (milling with gypsum pond water) was greater than the sum of erosion (milling with water) plus static corrosion. Erosion-corrosion wear was about 1,500 to 3,000 mpy for the alloyed white cast irons, 1,000 to 1,400 mpy for commercial steel ball material and type 316 stainless steel, and 600 to 900 mpy for nickel-base alloys and a high-manganese, nitrided stainless steel. Alloy costs per unit of phosphate rock 'processed favor a low-alloy, high-carbon steel or a high-manganese, nitrided stainless steel.

Jan 1, 1985

By Gregory P. Cole, Jeffrey Shawn Peterson

The Pittsburgh Research center3 conducted research to study and improve electrical fault detection on coal mine direct-current (dc) trolley systems. A suspended trolley line delivers power at voltages of 300 or 600 V dc to the haulage equipment and other loads. Roof falls or other accidents may force the trolley line down so that an electrical fault current may flow between the trolley line and rail. This fault current could result in localized heating, arcing, and perhaps fire. Such faults are not always preventable by the existing circuit protection because the current magnitude is well below typical operating levels of the trolley system. The research discussed in this report studies the applicability of computerized signal analysis techniques to solve this problem. Tests were conducted at cooperating coal mines. Measurements were taken during normal loading of the trolley system (light, intermediate, and heavy traffic), during induced fault conditions (arcing and bolted faults), and during transitions between the two. These data were then used to train and test a microprocessor-based fault detection algorithm. Later, field tests of the detection algorithm found that it correctly classified the state of the trolley system greater than 95% of the time.

Jan 1, 1997

By David C. Oyler, Gregory Hasenfus, Gregory M. Molinda

Few studies have specifically measured and documented the large-scale loading behavior and durability of ventilation stoppings to mining induced movements, particularly from longwalls. Ventilation stoppings are more commonly the concern of ventilation engineers, and ventilation stopping response to ground movement has only been documented in an incidental manner. This paper presents the investigations of underground measurements that have been conducted to determine the loading response of stoppings constructed from lightweight aggregate concrete masonry units (CMU). These investigations have produced some interesting results that may prove beneficial, not only for developing and assessing alternative stopping construction techniques, but also for designing and selecting standard construction methods for use in varying mining conditions. For instance, the interface friction that results from wedging a CMU stopping during construction plays a substantial role in its ability to resist both lateral and vertical loads. Although they are not intended for ground support, the study showed that block stoppings can resist vertical loads of at least 2,700 to 3,000 kN. Asymmetric loading of a stopping may result in localized failure of blocks within a stopping, which, depending on the severity, can be a precursor of impending stopping failure. In addition to measurement results and implications, the paper will also present details of field measurement methods used to assess stopping response. Stopping stiffness and material strength characteristics will also be presented.

Geological discontinues in the coalbed, such as faults, sandstone channels, permeability facies, lithotype changes, and large scale partings in the coal seam, can cause intermittent production problems or produce unexpected amounts of water or gas from degasification boreholes. These discontinuities not only can impact methane emissions into the mine workings, especially if they hinder proper and effective degasification of the coalbed but may act as conduits for methane flow from gassy strata into advancing mine workings. The effects of these discontinuities are still under debate by mining and gas production experts. This study presents a numerical investigation using reservoir simulations of the effects of partings and permeability facies and lithotype changes on the production performances of vertical and horizontal degasification boreholes, as well as the emissions during longwall operations. In this work, the grid block was designed in a multi-layer 3-D structure which enabled spatial descriptions of the geometries and properties of the discontinuities within the coal seam. The studied coal seam discontinuities and their properties were distributed arbitrarily within the model. Production was simulated by vertical and horizontal boreholes. Degasification boreholes operated two years prior to start of the mining. The results of this numerical study show that in coal seams with major heterogeneities and discontinuties, the geometry and location of the boreholes are important for improved gas production. These considerations are also important for controlling methane and water inflow into the working environment during longwall mining.

Jan 1, 2008

By R. A. Beall

As part of an ongoing program to develop high-quality materials with improved performance and service lives, and to conserve critical minerals, Bureau of Mines, U.S. Department of the Interior, researchers studied the process of hot-rolling metals, alloys, and composites in vacuum. First, a comprehensive review of the literature is presented, including the advantages and disadvantages of using vacuum. Next, details of hot-rolling titanium, chromium, and molybdenum-iron bimetal are given. Finally, the design of new equipment is described. At this time, it is uncertain whether hot-rolling metals in vacuum will gain commercial acceptance in the future.

Jan 1, 1979

By J. M. Riley

A fluorometric method using morin in an alkaline-buffered chelating solution has been developed by the Bureau of Mines for determining beryllium in ores and mill products. Apparatus for measuring fluorescence intensities of the beryllium-morin reaction is described. Preparation of the sample for analysis consists essentially of digestion with sulfuric, nitric, and hydrofluoric acids, fusion of the residue with sodium carbonate and sodium borate, Solution of the melt with sulfuric acid, and proper dilution. Chemical separation of other ions is usually unnecessary. The method rave reliable beryllium determinations on samples in the 0.01- to 0.37-percent BeO range. The method is particularly applicable to low-grade beryllium ores; however, semiquantitative beryllium determinations have been made on beryl containing 12.0 percent BeO.

Jan 1, 1956

By Jr. Driscoll

The thermoelectric properties of yttrium monoarsenide, yttrium monoanti-monide) and ternary materials from the Y-As-Se and Y-Sb-Te systems were investigated by the Bureau of Mines from room temperature to 1,000° C. The maximum calculated figure of merit for yttrium monoarsenide and yttrium monoantimonide was 2 x 10-5 ° C-1. YAs and YSb were semimetallic conductors with low Seebeck coefficients and electrical resistivities. The values of the Seebeck coefficient and electrical resistivity of the Y-As-Se and Y-Sb-Te materials were between those of the yttrium selenides and tellurides and of YAs and YSb, respectively. The maximum power factor calculated for the Y-As-Se materials was 2 X 10-5 watt/cm ° C2 which yielded an estimated figure of merit of 6 X 10-4 0 C-1. Most of the Y-As-Se compounds had high Seebeck coefficients and moderately low electrical resistivities. The Y-Sb-Te materials were degenerate semiconductors with power factors of 6 X 10-8 watt/cm ° C2.

Jan 1, 1967

By D. Harrington

Although the explosion-fatality record for the fiscal year 1944 showed considerable improvement over those of the preceding 4 years, it is still fur from creditable, and the coal-mining industry and agencies interested in the prevention of coal-mine accidents should not be satisfied until accidents from explosions and fires are eliminated. In view of present knowledge of the methods of preventing explosions and fires, such disasters are inexcusable and discredit the mining industry. Despite this knowledge, far too many coal¬mine operators and employees continue to follow procedures that have resulted in disasters in the past. Included in the appendix to this circular are a number of safety measures designed to prevent coal-mine explosions and fires and metal-mine fires. Their adoption is essential if explosions and fires are to be prevented, as certainly they should be. An epidemic of disastrous mine fires of electrical origin during the past 2 years emphasizes the need for better methods of protection of underground electrical circuits. At present, committees of mining-electrical engineers, electrical-equipment manufacturers' representatives, and others are cooperating with the Bureau of Mines seeking means to solve this problem.

Jan 1, 1945

By John P. Carter

The U.S. Bureau of Mines conducted research to determine suitable construction materials for use in brine and steam environments produced from high-salinity geothermal brines. The high-temperature, high-salinity geothermal brines in the Salton Sea Known Geothermal Resources Area (KGRA) are a valuable source of energy and mineral values. The brine and steam produced from them are corrosive and cause early failure of many common materials of construction. Mass-loss and electrochemical corrosion measurements were conducted on over 60 metal alloys in brine and steam environments produced from geothermal well Magmamax No.1, located at the Salton Sea KGRA, at temperatures from 1800 to 2150 C, and in synthetic Magmamax brine at 105° and 232° C. General corrosion, crevice and pitting corrosion, and stress corrosion were examined along with the effects of dissolved gases. The alloys with the most acceptable corrosion performance in high-temperature, high-salinity geothermal environments were the high-chromium ferritic stainless steels, the Inconels and Hastelloys, and the titanium alloys. Specific alloys that performed well in wellhead brine included Fe29Cr4Mo, E-Brite 26-1, stabilized Fe26Cr1Mo, 6X, Inconel 625, Hastelloy C-276, Hastelloy S, Hastelloy G, Ti5OA, TiO.2Pd, and TiCode 12.

Jan 1, 2010

By Jeffrey Y. Foley

Chromite deposits along the Border Ranges Fault in southern Alaska were investigated by the Bureau of Mines. This report, part 1 of a two- part series, describes the deposits. Part 2 describes the mineralogy and the results of metallurgical tests. Fieldwork began in 1981 and continued through 1983. Ninety-four subeconomic podifom chromite deposits in eight mafic-ultramafic complexes were investigated. Previously unreported chromite deposits at Red Mountain on Kenai Peninsula, on Kodiak Island, and near Tonsina are described. Deposits range in size from less than a thousand tons to over 1.25 million tons of contained chromic oxide (Cr203). Grades range from about 5 to 10 pct chromite. Excluding all deposits more than 10 miles from tidewater or existing roads and all deposits containing only chemical- or refractory-grade chromite, about 2,200,000 tons of Cr203 are contained in 41 hard-rock deposits. A placer deposit contains an additional 556,000 tons. These 42 deposits constitute a subeconomic indicated and inferred reserve sufficient to meet the Nation's chromite demands for about 4 yr, or the metallurgical industry's demands for over 5 yr, at 1981 consumption rates.

Jan 1, 1985

By C. A. Komar

The Bureau of Mines conducted experiments on one synthetic and three natural sandstone samples to investigate the effects of acoustic energy on the flow of brine in porous media. Ultrasonic energy at a frequency of 20 kc per second and an intensity of 55 watts per cm2 was irradiated in the direction of the fluid flow and in the opposite direction for distances of 1/2 and 2 inches between the vibrating device and the sample face and under conditions of suppressed and nonsuppressed cavitation. Forty tests were conducted: 32 with a pressure differential of 0.64 psi across the samples, 2 with 5 psi, and 6 with 15 psi. Acoustic waves altered the rate of flow of the brine through the samples, but this effect was observed only at low differential pressures and from a practical point of view was insignificant. As a result of irradiation, however, the samples exhibited reduced permeability. This reduction was probably caused by the shifting of solid particles dislodged by the acoustic waves.

Jan 1, 1967