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By Jerome J. Hoeppner, Walter W. Fowkes

The Federal Bureau of Mines has determined the distribution of forms of sulfur for several lignites and gasification chars and noted the changes induced by the gasification process . A method was adopted for quantitatively determining sulfide sulfur that was found to be present in the chars , although absent in the lignites . Changes in the behavior and distribution of sulfur forms were further investigated concerning the ashing of lignites and chars under standard conditions , as well as at various temperatures , and the determination of volatile matter applied to both chars and lignites . The authors concluded that the first and greatest change in the form of sulfur present in natural lignite , upon heat treatment , resulted from the reduction of pyritic and sulfate sulfur to sulfide . Organically - bound sulfur originally present is less reactive , but largely disappears on strong ignition . An appreciable part of the sulfur content of natural lignite is fixed in the char as sulfide and in the ash as water - soluble sulfate and will affect the summation of constituents , to a greater or lesser degree , in reporting the ultimate analysis of a lignite or char .

Jul 1, 1960

By K. A. Fowler, L. W. Higley

The effect of uranium on the transformation kinetics and the hardenability of a low- alloy steel was evaluated . Isothermal transformation curves were developed from metallographic studies , and hardenability was determined by standard Jominy end- quench tests . For the steels investigated , the addition of 0.15 weight- percent uranium was found to produce a significant shift in the isothermal transformation curve and caused a related increase in hardenability . These effects diminished rapidly when the uranium content was increased above 0.2 weight - percent .

Jan 1, 1964

By A. F. Cohen

When location guidelines are followed in choosing sites for fixed point velocity transducers for use in underground coal mine monitoring, mine air turbulence intensities <11% are generally expected at those sites. The objective of this Bureau of Mines investigation to determine the effect of turbulence intensities <11% on vortex shedding sensors and transducers. Measurements were made at velocity levels of interest for underground coal mine monitoring use (?200, ?500, ?1,000, ?1,500 ft/min). The effect of grid-produced turbulence intensities (2% to ?14%) on the output of vortex-shedding air-velocity transducers was less than ±10%.

Jan 1, 1985

By William J. Campbell

These investigations were undertaken as part of a program to determine the optimum X-ray spectral lines to use for analyzing the wide variety of samples received by the X-ray Laboratory. Theoretical calculations and experimental data derived from these investigations show that longer wavelength spectral lines, > 2A, are very useful for many analytical problems. Because of the low fluorescence yield of the elements of atomic numbers 13-22 and the small depth of penetration of their X-ray spectral lines, these elements were originally considered to be insensitive; however, these studies show that the wide dispersion of their spectral lines, coupled with their weak beta lines, permits the use of wide collimation, thus increasing the line intensity. More importantly, the background due to scattered primary radiation is very low in the long-wavelength region.

Jan 1, 1959

By Ludwig Schmidt

The policy of buying crude oil on a gravity basis , recently instituted by the major crude oil purchasing agencies in the Mid- Continent field , has caused a new and vital interest to be taken in the work of the U. S. Bureau of Mines for preventing evaporation of crude . From the early years of the industry oil men have recognized that the gravity of crude oil is usually an index of the gasoline content , but it has not been so generally known that the gravity of the crude oil decreases if evaporation is permitted . In 1919 the Bureau of Mines began a survey to determine the evaporation losses of crude petroleum in its various stages of handling from the well to the refinery , The results of this study are presented in Bulletin 200 ( Wiggins , J.H. , Evaporation losses of petroleum in the Mid- Continent Field , Bulletin 200 , U. s . Bureau of Mines , 1922. ) and Bulletin 225 ( Wiggins , J.H. , Methods of decreasing evaporation losses of petroleum , Bulletin 225 , U. S. Bureau of Mines , ( In press ) The findings of this survey were so startling that soon after the preliminary report had been published , several tank companies began manufacturing vapor- tight tanks for the purpose of reducing these important losses . Since that time the development of this type of apparatus has been so rapid that today , every oil trade journal carries numerous advertisements of vapor- tight tanks and equipment as well as technical articles dealing with various problems in connection with the elimination of evaporation losses , whereas three or four years ago the subject was scarcely even thought of. The present report has been prepared in response to numerous requests for information on the apparatus actually being used to prevent evaporation losses . At this time oil operators are also extremely interested in holding the lighter fractions in the crude oil in order to prevent a lowering in gravity . The practice of removing the vapors from crude- oil tanks by means of a slight vacuum and extracting the gasoline from them is not discussed here .

Feb 1, 1923

By Jianmin Qin, Raja V. Ramani, Wilson Miola

"The number of underground work entities operating under reduced dust standards in U.S. coal mines has been increasing since the start of the decade of the 80s and is currently approaching 10,000. The concern for controlling the quartz levels in airborne respirable dust in coal mine has manifested itself in several improvements in equipment selection and operation, face ventilation practices, and dust control procedures. At the same time, fundamental studies have been initiated on determining the source-sink relationships of the airborne quartz dust. The P-7 method is the prescribed method for the determination of quartz in the respirable airborne dust samples from coal mines. Questions have been raised on the reliability of the P-7 infrared spectrometry method for quartz analysis in powders. No specific method has been defined for quartz determination in bulk samples from the mine.In a recent study on the relationship between quartz in the airborne dust and that in the materials being mined, both infrared (IR) and x-ray diffraction (XRD) methods were used on a suite of samples from several coal mines. These samples encompassed airborne respirable dust samples, airborne total dust samples, the oversize fraction from the respirable samplers, ROM samples, channel samples, and chip samples from the face, roof, and floor materials. In this paper, the sample preparation and analysis procedures for the samples are discussed. The data, analysis results, and comparisons of the P-7 and XRD results are presented. The quartz percent determined for the same sample by the two methods are different. In 85% of the samples analyzed, the quartz percents determined by the XRD method are higher than those obtained by the P-7 method. However, there is a strong linear relationship between the results from the two methods. Further, the XRD method indicates an average of 20 percent more quartz than that from the P-7 method. The reasons for the differences in the results and the need for additional studies are explored.Since the enactment of the Federal Coal Mine Health and Safety Act of 1969 and the Federal Occupational Safety and Health Act of 1970, the prevalence of free silica as an occupational hazard in dusty work environments has been a matter of increasing concern. In underground coal mining, sometimes, roof, floor, clay veins and other non-coaly material must also be mined along with the coal. Mining these materials may increase the amount of quartz in the airborne dust (Pimentel and Adam, 1985; Taylor et al., 1984; Colinet et al., 1985). The problem of high quartz levels in the respirable airborne dust is widespread in continuous miner sections. In addition to the need for controlling the silica amount in mine atmosphere, a need for a sensitive, easily performed method for the determination of free silica in airborne dust samples was also recognized."

Mar 1, 1992

By Eric R. Bauer

This Bureau of Mines publication describes and illustrates the physical signs of excessive loading on mine roof supports, installations, and openings. It is designed to assist mine personnel in recognizing potentially hazardous ground conditions, by emphasizing the preliminary effects of developing unstable ground. Increased worker awareness can be expected to reduce the injuries and fatalities resulting from falls of roof, rib, and face.

Jan 1, 1985

By Hillary W. Clair

An equation is derived for the rate of reaction of a sphere of metal oxide in a restricted enclosure through which a reducing gas is flowing . The equation takes into consideration the reaction rate coefficient , transport through the gas and through the porous shell of reduced oxide , the rate of gas flow , and the volume of the enclosure . The equation serves as a model for predicting the course of reduction of a particle of metal oxide in a shaft furnace .

Jan 1, 1964

By Sidney Katell

This Bureau of Mines study estimates typical capital investments, operating costs, and selling prices for two bituminous coal strip mines in the Eastern and Interior provinces and a subbituminous coal operation in the Northern Great Plains province. The annual productions were based on tonnage required to fuel a 250-MM-scfd, high-Btu gas plant. The annual tonnage for the Eastern province mine is 4.8 million tons; for the Interior province mine, 6.72 mi 11 ion tons; and for the Northern Great Plains province mine, 9.2 million tons. It is assumed that the mines have a 20-year life. Wages and union welfare payments are considered as of May 12, 1974, under the terms of the Bituminous Wage Agreement of 1971, and costs for material and equipment are based on 1973 and early 1974 indexes . Initial capital investment varies: $45,358,600 for the 4.8-million- ton-per-year (MM tpy) mine in the Eastern province, $54,603,000 for the 6.72 MM tpy mine in the Interior province, and $29,871,000 for the 9.2 MM tpy mine in the Northern Great Plains province. Total capital invest-ments for the Eastern province mine, the Interior province mine, and the Northern Great Plains province mine are $61,070,000, $76,753,000, and $56,286,000, respectively. Corresponding selling prices for the coal, per ton, are $4.79, $4.23, and $2.66, assuming a 12-percent discounted cash flow rate of return after Federal income taxes. These studies are considered typical for the areas involved. Costs will vary depending on specific locations in these areas.

Jan 1, 1974

By Virgil A. Marple, Susanne V. Hering

"5.1 IntroductionTraditional impactors do not offer much size resolution for submicrometer particles; typically their finest size cut is around 0.4 µ.m. Yet for many aerosol applications it is useful to be able to size segregate aerosols in the size range below 0.4 µ.m. Diesel emissions, welding fumes, cigarette smokes and photochemically generated smog aerosols typically exhibit mass median diameters between 0.1 and 0.6 µ.m. When sampling these aerosols with a traditional impactor, fifty percent or more of the aerosol mass can penetrate the final impactor stage. Allhough the material can still be collected on a backup filter, the filter gives no size resolution. As a result, the investigator has no size information on a substantial portion of the sample. One needs a sampler that size-segregates the majority of the aerosol mass. A lower size cut of 0.1 µ.m or less is required for most combustion smokes and smog aerosol s.To obtain smaller cutpoints two types of impactors have been developed, namely low-pressure impactors and micro-orifice impactors. Both instruments can provide cutpoints as small as 0.05 µ.m. Low-pressure impactors were introduced more than twenty years ago (Stem et al., 1962), and a variety of these samplers are in use today. Micro-orifice impactors have been developed at the University of Minnesota within the last five years (Marple et al., 1981 ). To date theirs are the only examples of these instruments in use.5.2 Operating PrinciplesThe low-pressure and micro-orifice impactors use two different approaches to achieve their very small particle-size cuts. Low pressure impactors resemble ordinary impactors, but are operated at reduced pressures of 5-40 kPa (0.05 - 0.4 atm). They take advantage of the decreased aerodynamic drag on particles that occurs when the mean free path in the air is as large or larger than the particle diameter. Micro-orifice impactors operate at near atmospheric pressure, but employ very small orifices, 40 µ.m to 200 µ.m in diameter. The streamlines of the air impinging upon the impaction plate have correspondingly smaller radii of curvature; the air is accelerated more quickly, making it more difficult for the particles to follow. The basic operating principles for both types of impactors are evident from the particle Stokes number, defined as:"

Mar 1, 1989

By J. Howard Bird

The purpose of this publication is to describe the power-distribution system of the mine and refinery of the Duval Sulphur & Potash Company at Carlsbad, N. Mex. This distribution system has been excellently predesigned to meet requirements and fit special conditions encountered at the property. In presenting the material, the authors point out various features that would be desirable for incorporation in other systems under similar conditions. Central location of switchgear in pressurized vaults and ventilation of such equipment with filtered air prevent salt accumulations and contribute to trouble-free operation. The simplification of power-distribution circuits and overload protection, as a result of centralization of switchgear, the use of individual control circuits enclosed in conduit (which aids troubleshooting), and central location of control panels, are factors which contribute to efficient, safe operation. Those features are applicable to many operations where fire or explosion hazards are encountered, or where dusty conditions may exist, as well as in operations where numerous individual drives are involved.

Jan 1, 1959

By Michael D. Balen

During the years 1987 through 1989, the Bureau of Mines Alaska Field Operations Center (Bureau) in cooperation with the Western Field Operations Center and the Alaska Division of Geological and Geophysical Surveys (ADGGS), conducted mining, geological, and geochemical investigations in the 5.7 million-acre Valdez Creek Mining District (VCMD). This investigation was conducted as part of the Bureau&apos;s continuing Mineral Land Assessment (MLA) mining district studies program. The Bureau&apos;s MLA program is designed to provide reliable and comprehensive mineral resource information that supports mineral resource policy and land use decisions made by Congress and Federal land management agencies. The information also provides the basis for decisions that would expand the domestic supply of important mineral resources, primarily strategic and critical minerals. Much of the MLA work is done jointly with cooperating State or U.S. geological surveys.

Jan 1, 1992

By William R. Wayment, David E. Nicholson

A modified percolation - rate test is proposed for use in determining flow rates through hydraulic backfill ; in contrast to the conventional test , a percolation- rate versus void - ratio relationship is established . requirements and a detailed test procedure are described . Equipment Results of a conventional test are compared with those of the proposed modified test . The proposed modified test method yields more accurate , realistic , and usable percolation- rate ( permeability ) data . The significance of obtaining accurate percolation rates for use in analyzing waterflow through hydraulic backfill is discussed .

Jan 1, 1964

By K. Shimamoto

This study has been prompted by the anticipated demand for rhenium by the petroleum industry and the concern for an adequate supply of rhenium to meet the demand. The present and projected outlook for rhenium relative to its distribution and occurrences, the recovery factors involved in ore beneficiation, capital and operating costs, changing technology, and the projected uses and market growth of rhenium are presented in this report as part of the Bureau of Mines program to determine the availability of recoverable rhenium in a developing market.

Jan 1, 1973

By Ronald S. Conti

This U.S. Bureau of Mines report discusses the results of research conducted in the Bureau&apos;s experimental mine at Lake Lynn Laboratory on the response of fire sensors to simulated mine fires, which included (1) a slowly developing coal-conveyor belt fire, (2) a rapidly burning liquid fuel-belt fire, and (3) a liquid fuel-belt fire in the presence of diesel exhaust. During these tests, several mine fire sensors were evaluated with respect to sensor placement, spacing, and type. The data indicate that smoke sensors alarm several minutes before CO sensors do; and that, in the presence of diesel exhaust, a prototype diesel-discriminating smoke sensor can successfully function without being sensitive to the diesel contaminants. The vertical placement of sensors in the entry near the fire was also shown to be critical in terms of alarm times. Additional data showed that variations exist in response time and level of response for two brands of electrochemical CO sensor. Results also indicate that early detection of fires will improve the probability of miners&apos; escape, because of reduced smoke concentrations during the incipient stages of the fire.

Jan 1, 2010

By J. Burlin Johnson

This report describes an investigation of the relationship between crater dimensions formed in laboratory blasting experiments and the mechanical properties of the material cratered. Scaled field data have been included when available. The results show that tensile strength and possibly other mechanical properties may be useful in predicting maximum crater dimensions.

Jan 1, 1963

By R. Karl Zipf, Z. T. Bieniawski

"Abstract. Based on the premise that understanding the fundamental mechanics of fine fragment formation in coal will lead to reducing coal dust problems in mines, a thorough study of the mechanics of crack propagation in coal was undertaken. Two approaches were considered in an attempt to understand and quantify the fracture process as it relates to fine fragment formation.In one approach, theoretical models are used which describe the size of the fracture process zone which may relate to the amount of structural damage and fine fragment formation on the new crack surface. The other approach is based on the relationship between crack tip stress intensity and new surface appearance for mixed mode crack propagation. Preliminary observations with a scanning electron microscope support the premise that fine fragment formation is related to fracture surface appearance and fracture initiation conditions.An experimental program designed to supply the input parameters for these approaches is presently underway. The experimentation features mixed mode fracture toughness testing, using a special mixed mode testing rig, and fracture velocity measurements with a crack propagation gage. The interpretation of this data via the approaches discussed will provide further understanding of the mechanics of fine fragment formation in coal."

Mar 1, 1989

By Chase E. Sutton

The porosity of a sand is usually the measure of its capacity for holding fluid, although porosity is sometimes selective; that is, a small percentage of the actual pore space (voids), particularly in fine-grained sandstones, may be isolated by the cementing material which prevents the entrance of fluids under normal conditions. Obviously, however, porosity determinations are essential to an engineering study of underground conditions of an oil field, and a simple and reliable method of obtaining a reasonably accurate figure for average porosity is desirable. This report describes a method suggested by Ruasell,3 which was used by the writer in the preparation of a report on the Texhoma-Gose pool, Archer County, Tex.4 The conditions in this pool were particularly favorable for obtaining an average porosity figure, in that some 30 to 35 core samples of the pay sand were available for analysis.

Jan 1, 1928

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 J. A. Cavallaro

The heats of formation of anhydrous barium carbonate (witherite), strontium carbonate (strontianite), and lead carbonate (cerussite) were determined by solution calorimetry. The solution mediums were hydrochloric acid for barium and strontium carbonates and perchloric acid for lead carbonate. The heats of formation at 298.15° K are as follows: BaCO3 -297.5 ± 0.8 kcal/mole; SrCO3 -294.6 ± 0.5 kcal/mole; and PbCO3 -168.0 ± 0.3 kcal/mole.

Jan 1, 1966