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By R. V. Ramani, S. Shankar

"The phenomenon of re-entrainment is seen in environments such as sand dune formation, soil erosion, fugitive dust emission and the spread of radionuclides from accidents involving nuclear weapons. A thorough review of existing literature reveals that work on re-entrainment of dust in mine atmospheres is scant. The present study was undertaken as a part of ongoing research at the Generic Mineral Technology Center on Respirable Dust at the Pennsylvania State University on the development of methods to predict ambient dust concentrations in mine atmospheres (Ramani, 1983). The contribution of re-entrainment to the spatial and temporal concentration of dust in mine airways is being studied. The research has included wind tunnel and in-mine studies.A set of seven experiments was performed under controlled conditions in the US Bureau of Mines' Lake Lynn Laboratory mine. Two types of source coal dust, anthracite and bituminous, were subjected to various airflow rates and were subjected to walking by two different individuals. Six sets of instruments were used along the test section for sampling airborne particles. The average air velocity just above the coal dust bed varied between 2.1 to 3.2 m/sec.Due to re-entrainment as a result of the airflow conditions, the average respirable dust concentration in the center of the mine airway increased to 0.09 mg!m3 (standard deviation= 0.03 mg/m3)from an initial value of 0.02 mg/m3. The concentration of all (total) airborne dust increased to 0.17 mg/m3 (standard deviation = 0.10 mg/m3) from an initial value of 0. 02 mg/m3. The action of people walking, however, caused higher amounts of re-entrainment. The average concentration of respirable and total dust at the center of the mine airway increased to values of 0. 28 mg/m3 (standard deviation of 0.12 mg/m3) and 1.53 mg/m3 (standard deviation of 1.0 mg/m3), from initial values of 0.03 and 0.05 mg/m3, respectively. Jr was observed that the dust concentrations were much higher near the floor, immediately at the end of the coal-dust bed.Depending on the level of activity and the amount of dust deposited in the mine airways, re-entrainment may become an important source of airborne dust in areas away from the point of actual mining."

Dec 1, 1996

By R. M. Ray

The Bureau of Mines evaluated five commercial badge-type carbon monoxide dosimeters. Color changes in the badge reagent indicated the presence of carbon, monoxide. Possible effects of ambient conditions on dosimeter response to CO during or after coal mine fires or explosions were studied. Temperature and humidity changes did not change dosimeter sensitivity to CO. Contaminant gases such as CO2, N02, S02, and H2S had effects that varied with brands of dosimeters ranging from no effect to increased sensitivity to CO. Dosimeters tested after 6 months of storage showed an increase in failure rate as high as 25 percent. Tests were conducted to determine the effects on dosimeter time-for-color change caused by observer's sight (colorblind); lighting, and coal dust on dosimeters. No significant effects were observed. Observer variance was the most pronounced factor observed in all tests.

Jan 1, 1975

By R. W. Lewis

The Federal Bureau of Mines Boulder City Metallurgy Research Laboratory conducted experiments in order to develop a spectrochemical method for determining the concentrations of impurities In high-purity tungsten. This report presents a procedure, developed by these experiments, for determining 19 impurities in high-purity tungsten. Metal samples were thermally converted to the oxide, mixed with graphite, which was prepared and mixed with an internal-standard element, and excited in a d.c. arc. Sixteen of the impurity elements were determined with one set of conditions, using germanium as an internal standard. Lanthanum was used as an internal standard in the tests for boron and chromium. Molybdenum required the substitution of sodium chloride for the graphite and the use of copper electrodes. Data on the precision of the method are included in this report. The coefficients of variation vary considerably but average about 15 percent. Higher concentrations of impurities than those investigated may be determined with some modifications of the testing procedure, provided attention is given to the possibility of interelement interferences.

Jan 1, 1961

By James V. Kelly

During the spring and summer of 1947, the Bureau of Mines conducted an investigation and core-drilling program in the vicinity of the Rodham mine, approximately 4 miles north of Shullsburg, Wis. This work was undertaken as a part of a general study of the zinc and lead-producing area of southwestern Wisconsin. Work in the Rodham-mine area was done to investigate further a mineralized area frilled in part by the Puritan Exploration Co., a Delaware corporation, with offices in Galena, Ill. Some significant lead-bearing samples were obtained, but no continuous ore body was disclosed as a result of the Bureau of Mines work.

Jan 1, 1949

By F. M. Boler

The U.S. Bureau of Mines has configured a flexible data acquisition and analysis workstation, which incorporates control and analysis software written in-house for use in mining research experiments conducted in the laboratory and in operating underground mines. This data acquisition system combines computer-automated-measurement-and-control (CAMAC) modular instrumentation with a Unix-based graphics workstation. The data acquisition front-end hardware can be interfaced to almost any computer. CAMAC instrumentation modules adhere to mechanical, electrical, and digital interface standards and can be custom designed or purchased off the shelf. Communications along the CAMAC bus are regulated by the crate-controller module, which contains the only hardware link to the computer interface. Software support for the data acquisition and analysis workstation consists of a series of functions and programs written in the "C" programming language designed to provide flexible and fast data acquisition, processing, and analysis. The user can interactively control the digitizers and other CAMAC modules by sending standard CAMAC read, write, and command function codes from a menu-driven program. Automated data collection is achieved through software that responds to hardware interrupts triggered by acoustic emission or microseismic events. Graphics display routines are used to plot part or all of the data and provide the ability to process and store signal information selectively.

Jan 1, 1990

By W. T. Culler

"The ""rate-of-preduotion curve"" described in the revised Treasury Manual* was devised by the author in May, 1920, and since that time has been use by the oil and gas valuation section of the Treasury Department in determining the rate of production of wells for purposes of taxation. This curve is most useful for estimating the future production of a well, or group of wells, of known daily settled production, where future-production curves and tables based on yearly production records are available. It also provides a means for determining the past year's production of a well of known daily settled production, or conversely, the estimated production on any day for a well of known yearly production.The rate-of-production curve is auxiliary to the production decline curve and is derived from it in estimating the future production of a tract, a production decline curve formed from the records of the tract itself should be used. If such records are not available, and there is no information which leads to the belief that the average production decline of the wells in this tract differs from the average for the pool or district, an average curve for the pool or district may be used.The accompanying chart illustrates a typical rate-of-production curve, with the yearly production decline curve from which it is derived. The production decline curve shown is for an average well in the Augusta district, Butler County, Kansas, and has been constructed from the tables given on page 128 of the revised Treasury Manual.The ordinate (vertical scale on the chart) of any point on a yearly production decline curve represents the production of the well during the year previous to the date shown by the abscissa (horizontal scale). For example, the chart shows that an average well, which produced 100,000 barrels of oil in 1915. produced 92,000 barrels in the year previous to January 19, 1916, produced 53,300 barrels in the year previous to June 1, 1916; produced 49,000 barrels in the year previous to July 1, 1916, 27,000 barrels in 1916, and 10,000 barrels in 1917."

Oct 1, 1921

By Frank K. McIntosh

The Hamme tungsten district is in Vance County, N. C., and Mecklenburg County, Va. Principal development has been in Vance County. The district is approximately 8 miles long by 1 mile wide and extends northeast-southwest. Its center is about 3 miles N. 65° W. of Townsville, N. C. The occurrence of tungsten in the district was first reported in 1901, but it was not until the Hamme brothers revived interest in the deposits in 1942 that commercial development began. The Bureau of Mines, as part of the war minerals program, began exploration and development of the district in June 1943 and completed it in December 1943. The Federal Geological Survey cooperated by mapping the topography and geology and logging the drill cores. The program included mapping, trenching, sampling, diamond drilling, and analyses and beneficiation of ore samples, The principal ore mineral is hubnerite, which occurs in quartz veins within the schist and granite. The veins are generally lenticular along the strike and dip. About 50 quartz veins have been noted in the area, but many are barren or slightly mineralized.

Jan 1, 1948

By William H. Schiffbauer, William D. Mayercheck, August J. Kwitowski

This report summarizes work sponsored by the Bureau of Mines in the development of a remote operating system (ROS) for controllng a thin-seam continuous miner (TSCM) 500 feet or more distant from the extraction face. Detail s are provided on ROS subsystems including the continuous miner, video equipment, controls and displays, the electronic control system, and the operator station.

By R. W. Holliday

To determine the copper and nickel content of reported ore occurrences in the Chippewa mine near Rockmont, Douglas County, Wis., the Bureau of Mines reopened and sampled the old shaft and workings during the summer and fall of 1953. Occurrences of native copper near Rockmont and others near Gordon, also in Douglas County, Wis., are in lava flows, which extend from the Keweenaw Peninsula of Upper Michigan southwest across Wisconsin and into Minnesota. Sporadic attempts have been made to find additional economic copper deposits in these flows since profitable mines were developed in Upper Michigan nearly 100 years ago. The Rockmont and Gordon areas were explored extensively more than 50 years ago. More recently, from August 1944 to duly 1945, an occurrence near Gordon was investigated by the Bureau.2/

Jan 1, 1955

By G. L. Oldright, Virgil Miller, F. K. Shelton, Keck. W. E., Horst Sieg

Potash is one of the principal foods and is necessary for the growth of most vegetables, grains, and fruits. For many years, this country depended entirely upon foreign sources for its supply of potassium compounds. However, during the last 15 years the domestic production of potash has gradually increased, as shown in table 1. 7/ Imports now supply only half of the American market. In 1936, the equivalent of 207,000 tons of K20 was imported, and 210,000 tons was produced domestically. In 1935, domestic consumption was approximately 420,000 tons of potash, a 57 percent increase over that for 1934 and surpassing previous peaks of 1928 and 1930.

Jun 1, 1937

By A. W. Fahrenwald

[In studying coarse sand flotation3/ the question of the relation between fineness of grinding and mill capacity logically arose. Everyone familiar with present fine-grinding practice knows that the capacity of a ball mill or similar mill is determined, among other things, by the fineness of the finished product. Undoubtedly a great many mining companies must have a good deal of data directly bearing on this point, yet no quantitative relationship between ball-will capacity and fineness of finished product has been established. The experimental study presented here is an effort to establish this relationship in a semiquantitative way. The subject is a tremendously large one and grows in complexity as the study becomes more searching. In this work the power consumed by the mill in the various experiments was not determined end neither vas the steel consumption measured; mill capacity only was considered.]

Jan 1, 1930

By Ronald S. Conti

Historically, underground mine rescue teams have received training only in the course of actual emergencies, or in simulated mine environments, usually on the surface, with placards to identify objects and hazards. Also, while U.S. Federal Regulations require all underground miners to walk escapeways and conduct fire drills every 90 days, this does not fully prepare them for the conditions that may be encountered in real escape situations, such as smoke filled entries. This paper describes technology and realistic training simulations that have been identified for the general workforce and mine emergency responders. Of all the technology evaluated by underground personnel, laser lights and lifelines were most beneficial in leading personnel to safety and out of the mine in smoke-filled passageways. These technological advancements can improve the state of readiness for rescue personnel and increase the chances of survival for personnel escaping from underground emergencies.

By James S. Browning

The purpose of this investigation was to develop a dependable and economic method for recovering spodumene and mica from pegmatites of the type found in Gaston County, N. C. Laboratory batch tests and continuous flotation tests were made by the Federal Bureau of Mines to determine the feasibility of treating the ore by flotation to recover high-grade spodumene and mica concentrates. The spodumene flotation circuit yielded concentrates containing 6.50 percent lithia (Li20), with an overall recovery of 81.8 percent of the lithia in the ore, The mica circuit yielded concentrates containing 97.5 percent mica, with a recovery of 82.5 percent of the mica in the spodumene tailing.

Jan 1, 1961

By Edward D. Thimons

As U.S. mines go to greater depths, the high temperatures and humidities characteristic of such depths make it difficult to maintain a comfortable environment in working areas. Better techniques for cooling these deep working areas are needed. At the Homestake gold mine in South Dakota the Bureau of Mines has tested a water spray cooler inserted into the fresh air vent tube entering a warm stope. The cooler supplied more than 6 tons of refrigeration to the stope air, which dropped from an inlet temperature of 83° F dry bulb and 75° F wet bulb to 73.5° F dry bulb and 71.5° F wet bulb. These preliminary results show the water spray cooler to be a feasible concept. However, there is a need for substantial refinement and further testing, and work on the concept will be continued under contract to the Bureau.

Jan 1, 1979

By R. K. Koch

The vapor pressures of liquid columbium and liquid hafnium were deter-mined by the Langmuir free evaporation method as a part of the Bureau of Mines program on the study of transition metals. An electron-beam furnace with a water-cooled copper crucible was used for melting. Temperature was measured with a two-color ratio pyrometer. Least-squares analyses of the vapor pres-sure data gave the following equations: [Logp (atm) = 5 .429 -31,310 T] for liquid columbium in the range 2,740° - 3,140° K, and [Log p (atm) = 5,690 28 T] for liquid zirconium in the range 2,500° -2,810° K. Third-law evaluations of each data set gave mean heats of sublimation (298.15° K) of 175.1±3.2 kcal/mole and 148.3±1.2 kcal/mole for columbium and hafnium, respectively. Second-law standard heats of sublimation determined from sigma plots and from sigma-prime plots agreed fairly well with the third-law values. The sigma-prime plots gave standard entropies of sublimation of 30.96±0.84 eu and 33.S6±0.44 eu for columbium and hafnium, respectively.

Jan 1, 1968

By R. F. Stewart

A sedimentation method involving the use of the Palo-Travis apparatus was found satisfactory for rapid determination of the size distribution of coal particles ranging from 10 microns in diameter to those passing an 840-micron opening (20-mesh sieve), The method is most useful for comparing the size distributions of samples of pulverized coal where the actual size of the particles is not required and is applicable to sieve and subsieve sizes of a wide variety of coals and chars that can be wetted and are heavier than water. An analysis, including all calculations, can be completed in 1/2 to 10 hours, depending on the time required for the finely divided coal to settle. A typical analysis requires about an hour, making this a rapid, precise method for routine size-distribution analysis of powdered coals. When used with coal particles smaller than 400 microns, the method is precise within 15 microns for wide variations in test conditions and within 5 microns for identical test conditions. The precision decreases as particle size increases, becoming unsatisfactory for particles larger than 400 microns (40-mesh). For precision within 15 microns, the samples must be equal in weight. Greater precision is obtained with 4-gram samples, but samples as small as l gram may be used.

Jan 1, 1961

By L. B. Berger

In this investigation, the ampoule type of carbon-monoxide (CO) detector which is manufactured under license of U. S. Patent 1,644,014 (October 4, 1927) was tested for sensitivity and reliability. This detector was devised primarily for examining the air of manholes and sewers for possible dangerous contamination with CO before workmen enter these places, but due to the simplicity of the device it may have a more general usage for examination of atmospheres which are known or suspected, to be contaminated with CO. Some of the suggested uses are the examination of the air in garages, tunnels, mines, around blast furnaces, gas plants, and in the home.

Jan 1, 1930

By J. B. Gayle

A 1/2-ton experimental coke oven was installed ac the Bureau of Mines Southern Experiment Station, Tuscaloosa, Ala., in 1948. Designated as the Tuscaloosa oven, this unit features a 17-inch carbonizing chamber, globar heating elements, and silica-brick walls designed to simulate as closely as possible the carbonizing conditions for commercial slot-type ovens. Because of the small force exerted on the oven walls in most tests conducted to date (probably owing to the practice of charging coals and blends at a moisture content approximating that normal to commercial plants operating in this district), little information has been obtained about expansion properties. Two sole-heated ovens have therefore been constructed and used as supplementary equipment for determining the expansion properties of coals tested in the Tuscaloosa oven. The reasons for constructing the Tuscaloosa oven, the details of design, the operating, characteristics of the oven and the reproducibility of results have been discussed in previous publications. 3 4 5/ The present report deals with the effects of substituting various high- and low-volatile coals for components of a selected base blend carbonized under conditions similar to those normally used for producing foundry coke. Results of tests of 11 coals and 14 blends indicate that several blends tested rave cokes having physical properties very similar to those produced from the reference blend.

Jan 1, 1957

By Philip C. Good

The Bureau of Mines investigated the feasibility of utilizing low-grade phosphatic shale as a feed for phosphoric acid production. Present practice in the phosphate mining operations of southeastern Idaho is to remove and either stockpile or waste low-grade phosphatic shales as the high-grade phosphate beds are selectively mined. Acid digestion studies were performed on uncalcined shale and on shale calcined to remove free carbon to determine phosphoric acid quality, yield, and amenability to filtration. The untreated shale, containing 21.4 pct P205, was digested with sulfuric acid in a single-tank reactor to yield phosporic acid and gypsum residue. Although 96 pct P205 recovery was attained in digesting uncalcined shale, only the calcined product gave satisfactory filtration rates. Calcined shale yielded phosphoric acid recovery of about 93 pct of the contained P205. It was higher in impurities than commercially prepared acid derived from high-grade western phosphate rock. An acid filtration rate of 745 lb P205/ft2/day was attained. This value is lower than the rate of 900 lb P205/ft that is generally considered to be acceptable in industrial production of phosphoric acid from high-grade phosphate rock.

Jan 1, 1981

By T. T. Campbell

A survey of the literature eras made covering the use of aqueous non-aqueous, and fused-welt systems for the electrowinning or electroplating of molybdenum metal. The survey was prepared in order to provide background for further investigations directed toward the electrodeposition of pure molybdenum metal from either aqueous or nonaqueous mediums. While a thorough effort was made to cover all available references, a critical review was not attempted nor does this survey pretend to be exhaustive in nature.

Jan 1, 1955