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By Manuel Gomez

The heat contents of thermally dried lignite, subbituminous B coal, and their corresponding low-temperature chars were determined at various temperatures below the highest temperature to which these materials had been exposed before testing. Similar studies were made on high-temperature char and coke, spent shale, and ash prepared from both coal and spent shale. Heat content of the carbonaceous materials tested correlated well with temperature. Heat con-tent results for spent shale compared well with the published results. Statistical analysis of experimental data together with published information showed moisture, volatile matter, carbon content, and temperature to be the principal variables influencing the specific heat of coal. The specific heat of devolatilized carbonaceous substances, char and coke, approached that of graphite as the carbonization temperature was increased. The elemental specific heats of coal constituents, estimated from the ultimate analysis and the specific heat of coal, compared favorably with published elemental specific heats.

Jan 1, 1965

By R. Hogg, T. F. Dumm

"There is a considerable need for standardized respirable dusts with consistent, reproducible characteristics which simulate those of actual mine dust. The availability of such materials should be a significant factor in promoting coordinated research into dust characterization and mine monitoring, dust control, and the biomedical aspects of dust toxicology. The use of an opposed-jet, fluid-energy grinding system in closed circuit with a cross-flow, centrifugal air classifier for preparing bulk quantities of respirable-size dust has been investigated, and appropriate, standardized procedures have been established. By stage-crushing, screening, and fine-grinding with a Donaldson Acucut classifier/mini-grinder system, it is possible to produce bulk quantities of respirable dust at relatively high rates. Using minor modifications to the system, broader or narrower size distributions can be prepared within the respirable range. The system has been shown to reach steady-state with respect to product size distribution very rapidly. However, preferential grinding/classification effects appear to lead to a slow build-up of mineral matter in the circulating load with a corresponding slow change in product composition with time. In those applications where the dust composition is required to match that of the feed coal, it may be necessary to allow considerable time for a true steady-state to be established.Standard respirable dust samples have been prepared from coals representing the western (high volitile A bituminous), central (medium volatile bituminous) and eastern (anthracite) mining areas of Pennsylvania. Quartz and kaolin clay samples, representing important mineral constituents of coal dust have also been prepared. Extensive characterization studies have been performed on the samples to evaluate chemical and mineralogical composition and the distributions of particle size and specific gravity. Detailed information on the original coals is available from the Penn State Coal Data Base. The standard coal dust samples appear to simulate actual mine dust very well with respect to particle size and shape, but generally have somewhat lower ash content. Samples of these standard dusts have been made available to research groups concerned with respirable dust in mines."

Mar 1, 1989

By R. L. Grayson, W. E. Wallace, M. D. Attfield, A. Q. Wearden, P. Bolsaitis, R. D. Kennedy, M. J. Keane, J. C. Harrison

"Respirable high-silica particles from four coal mines. a clay mine and a tunnelling site were analysed for silicon vs aluminum composition by performing scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDS) at electron accelerating voltages of 20 kiloelectron volts (keV). The same particles were analysed at 5 keV to determine possible differences in surface vs bulk composition. In some cases high-silica particles exhibited a decrease in the ratio of silicon to aluminium K-alpha line intensities with decreasing electron beam accelerating voltage. This behaviour is consistent with aluminosilicate surface contamination or occlusion of a silica particle. Some 20 high-silica particles were analysed from each of 10 samples. Powdered aluminosilicate glass was used as a control for the behaviour of silica with a homogeneous distribution of aluminium in the particle. Significant differences were found between the control and sample means for an Illinois bituminous coal mine dust, two western and one central Pennsylvania bituminous coal mine dust low-temperature ashes. and a clay mine and mill dust sample, but not for an anthracite coal mine dust and two central Pennsylvania bituminous coal mine dust low-temperature ashes. INTRODUCTIONRESPIRABLE dust quartz content commonly is measured on bulk samples by using i.r. spectroscopy or X-ray diffraction. For research purposes, individual particle-by particle SEM-EDS analysis at 20-30 keV electron beam accelerating potential may be used also. Such measurements have not provided an unambiguous association of quartz content with occupational pulmonary disease prevalence in exposed workers (WALTON et al., 1977). Rather, there is evidence that coal rank modifies the relationship between dust exposure and pneumoconiosis development (WAL TON et al., 1977; ROBOCK and BAUER, 1990; ATTFIELD and MORRING, in press). SEM-EDS analysis was performed to measure the silicon fraction, Si/(Si +Ai), at 20 and at 5 keV on high-silica particles to determine if some respirable quartz particles generated by mining exhibit heterogenous composition with depth (WALLACE et al., 1990), which might affect the bioavailability of the quartz surface."

Dec 1, 1995

By O. C. Blade

This report on the properties of aviation gasolines and aviation jet fuels produced in the United States during 1952 was made under a co-operative agreement between the American Petroleum Institute and the Bureau of Mines of the United States Department of the Interior. Analytical data are presented for 94 samples of aviation gasoline which include, for the first time in this series of reports, data on five samples of grade 108/135 aviation fuel. Data also are given for 34 samples of aviation jet fuel. The analyses were made on samples typical of the manufacturers? production in their laboratories and the results submitted to the Bureau of Mines for compilation. The products of 20 manufacturers of aviation gasolines and of 16 producers of aviation jet fuels are represented.

Jan 1, 1953

By Foster Fraas

Almost all minerals show irreversible changes in electrical conductivity after heating in the temperature range 100° to 800° C. This effect can be detected with only a limited number of minerals with the standard ionizing-electrode-type separator, which differentiates between nonconductors and conductors in the single-particle resistivity range of 1011 to 1013 ohms. Tests outside this range with other type separators, such as the static field type, increase the number of minerals with which the effect can be detected to almost all that were tested. Irreversibility may be the result of an alteration of adsorption layers, volatilization of surface cations or anions, or an oxidation or reduction. One example is limonite, which decomposes to hematite and passes through two minima and two maxima in conductivity in the temperature range 100° to 900° C.

Jan 1, 1959

By J. W. Walkiewicz

The Bureau of Mines investigated alloys containing mischmetal (MM), cobalt, copper, magnesium, and iron for use in permanent magnets in place of the scarce samarium-cobalt alloys. The magnetic properties of MM-Co, MM-Co-Cu, MM-Co-Cu-Mg, and MM-Co-Cu-Fe-Mg alloys were evaluated. Magnets were fabricated by powder metallurgy consisting of arc-melting the metals, crushing and grinding the resultant alloys, alining and compacting the powder, and sintering the compacts. Magnetic values of MHc = 4.7 kOe, BHc = 4.07 kOe, Br = 6.81 kG, and (BH)max = 10.0 MGOe were obtained with a MM-Co alloy containing 36±0.5 wt-pct MM. By substituting copper and magnesium for part of the cobalt, the values for MHc and BHc were increased to 29.0 kOe and 5.89 kOe, respectively. This intrinsic coercivity value exceeded that of Sm-Co alloy obtained in our laboratory. The addition of iron to MM-Co-Cu-Mg alloys resulted in an increase of Br to 6.90 kG and (BH)max to 10.3 MGOe. Copper and magnesium contents of these alloys were optimized to obtain maximum values of MHc.

Jan 1, 1981

By Richard D. Miller

This Bureau of Mines publication contains analyses and related source data for 224 natural as samples from 18 States. Of the total, 191 sam¬ples were collected during calendar year 1981. The remaining 33 samples were collected during previous years, but releases, granting permission to publish were not received until 1981. All samples were obtained and analyzed as part of Bureau of Mines investigations of the occurrences of helium in natural gases of countries with free market economies. This survey has been conducted since 1917. The analyses published herein were made by the mass spectrometer and special helium apparatus described previously (1-2).3 The results of the investigation of the occurrences of helium are published annually to make the information available as soon as possible to the gas industry and the general public. Twenty-five publications have presented the results of 12,827 gas analyses made prior to 1981. The first three bulletins (1-3) contain analyses and related data on 5,218 gas samples collected from 1917 through 1960; these bulletins have been supplemented annually by information circulars (4-17, 19-24) containing 7,609 analyses of samples collected since 1960.

Jan 1, 1982

By E. G. Davis

The Bureau of Mines studied tailings samples from 11 large-scale western copper operations to determine the potential for recovery of rutile and other critical and strategic minerals. Up to 15 pounds per short ton (lb/st) Ti02 was found ion these samples; however, only 9 to 44 pct of the Ti02 was liberated rutile. For one sample, gravity preconcentra-tion, grinding, and flotation recovered 34 pct of the Ti02 in a 54.8-pct-Ti02 concentrate. Over 0.38 Ib/st W was found in some of the tailings sampleso Scheelite was identified as the major W mineral. Nine of the eleven samples contained about 0.02 to 0.18 Ib/st Co. Pyrite was the principal Co-bearing sulfide mineral, with Co contained in about one-fifth of the pyrite grains. Up to 30 pct of the Co was concentrated in a bulk sulfide flotation concentrate.

Jan 1, 1988

By William Y. Mo

This report presents preliminary results of a study undertaken to investigate quantitative characteristics of the demand for steel mill products and its major end-use components. The major end uses included in the study are the steel mill products used in construction, in automobiles, in producer durables, and in consumer durables. The main objectives of the research underlying this study are as follows: (1) To formulate and estimate the empirical demand relations for steel and the four major end uses in the United States; (2) to measure and calculate the responsiveness of the U.S. per capita steel consumption with respect to the changes of the steel and other nonferrous metals prices; (3) to determine and quantify the relative importance of the underlying demand explanatory factors in contributing to the average year-to-year increases (or decreases) of the U.S. per capita steel consumption; and (4) to adapt and use the estimated demand relations in making projections of the U.S. future demand for steel and the major end-use components. After extensive preliminary investigation, three versions of simple linear demand relations are selected and estimated by means of ordinary least squares (OLS) method. The annual data for the period 1947-65 are used in the estimation. Direct and cross price elasticities of demand are computed for each of major end uses. The relative importance of demand explanatory factors in contributing to the average year-to-year changes of U.S. per capita steel consumption are also calculated. For making projections, a simple autoregressive time trend model is used in estimating the future values of independent variables. Since the estimated demand relations are valid for projections only if the estimated parameters can be assumed to be unchanged in the future, and consequently, the projections derived in the study should be interpreted accordingly.

Jan 1, 1970

By Robert W. Smith

[In a certain application it was necessary to compute the incomplete beta function, ß(1/2, p, q), for a certain set of values of p and q. Since the set of p and q values was much more finely spaced than those in any published tables, the authors have decided to make their results available in this report. In connection with this application, the function ß(1/2, p, q) was needed at various points in the p, q plane at intervals of 0.05, 0.05 p = 2q < 10.00. Fletcher, Miller, and Rosenhead3/ state that the only tables available in the desired range are those of Pearson.4/ However, the interval used by Pearson was not small enough for the present application. For this reason, it was decided to calculate the function ß(1/2, p, q) for p = q = 0.05 (0.05) 10.00. This table is published because of the fundamental importance in mathematical analysis of the incomplete beta function.]

Jan 1, 1953

By Boyd Guthtrie

[Methods of distilling topped crude oils and distillates under vacuum, accompanied by good fractionation, have taken a place of major importance in the refining industry. In the refining of petroleum products it is generally desirable to produce a distillate of good quality, and this objective is attained by fractionation of a high degree. The laboratory and commercial practice have proved chat by varying the amount of fractionation the quality of the distillate car be changed, and refiners are cognizant of the advantages of good fractionation. Distillation-under high vacuum, however, is a relatively new practice in petroleum refining, and only during the last few years has there boon an indication that that this method ray become a general practice in the industry. Vacuum distillation offers many advantages over older methods of distilling petroleum products. Vacuum combined with steam distillation, for example, is replacing straight-stream distillation because the quality of the products of vacuum and, steam distillation surpasses that of those produced by straight-steam distillation. Although the injection of varying amounts of steam in a vacuum unit is common practice, the amount of steam used is becoming less as the vacuum within the unit is increased. This report describes tie construction of a visible-action laboratory batch still and fractioning; column and. gives curtain data pertaining to the operation of the apparatus under vacuum for the production. of lubricating distillates. The apparatus was designed and built to produce lubricating distillates under as nearly ideal conditions as possible, in order that a subsequent study of the characteristics of the distillates could be made.]

Jan 1, 1932

By B. B. Letson, D. F. Smith, T. E. Gardner, A. R. Taylor

Low- temperature heat capacities of strontium chloride (7° - 300° K) and strontium fluoride ( 11 ° - 300 ° K) were measured with an adiabatic calorimeter . Smooth values of heat capacity , entropy , enthalpy function , and free - energy function were calculated from the heat - capacity data . The smooth values are reported at 10 ° K intervals and at 273.15 ° and 298.15 ° K.

Jan 1, 1963

By S. L. Windes

"INTRODUCTION For a number of years the bureau of Mines has been engaged in the detection, recording and interpretation of earth- and air-transmitted disturbances, man-made and natural, related to mining operations. For the measure¬ment of such disturbances, special equipment was developed (1, 2, 3, 4, 8) 3/ and results of the measurements have been reported (5, 6; 7,9).In general, the ranges of amplitude end frequency of vibration encountered and recorded in the earth-transmitted disturbances were 0.00005 to 0.1 inch and 5 to 5,000 cycles per second; in the air-transmitted disturbances, pressures ranging from 0.001 to 100 pounds per square inch and 0 to 20,000 cycles per second were recorded.One characteristic of the earlier tests was that either the arrival time of the disturbance to be recorded was predictable or the recording speed was slow enough so that the record covered extended periods of time (for example, 4 hours). As the investigations continued, it became apparent that a recording device was required that would respond to transient vibrations arriving at indeterminate times and at the same time provide a permanent record of displacement or acceleration versus time on a scale that would permit the analysis of waves having frequency components up to 10,000 cycles per second. A film or paper speed of 720 inches per second was found to be adequate, as this provides approximately 3/4 inch of record for each 0.001 second."

Dec 1, 1947

By Margaret R. Egan

The U.S. Bureau of Mines conducted experiments in the intermediate-scale fire tunnel to assess the influence of air velocity on the gas production and smoke characteristics during smoldering and flaming combustion of Pittsburgh seam coal and its impact on the detection of the combustion products. On-line determinations of mass and number of smoke particles, light transmission, and various gas concentrations were made. From these experimental values, generation rates, heat-release rates, production constants, particle sizes, obscuration rates, and optical densities were calculated. Ventilation has a direct effect on fire detection and development. The results indicate that, in general, increased air velocity lengthened the onset of smoke and flaming ignition, increased the fire intensity, but decreased the gas and smoke concentrations. Increased air velocity also lengthened the response times of all the fire sensors tested. Rapid and reliable detector response at this most crucial stage of fire development can increase the possibility that appropriate miner response (fire suppression tactics or evacuation) can be completed before toxic smoke spreads throughout the mine.

Jan 1, 2010

By R. G. Meara, O&apos

The land-pebble district of Florida, which in 1928 supplied 96.7 per cent of the phosphate production of that State and 82 per cent of the domestic requirements of the United States, is centered in Polk and Hillsboro Counties about 30 miles east of Tampa The deposits are unconsolidated sediments occurring as beds of phosphate matrix overlain by a mantle of barren sands and clays. The matrix consists of a mixture of Sand (quartz grains), clay, and phosphate rock in which the coarsest sand is much finer than the coarsest phosphate; that is, the sand is segregated in the fine material. Before the introduction of classifiers the concentration consisted of log washing, and screening at about 20-mesh, which was usually the finest size that could be taken to maintain commercial grade, 66 per cent B. P. L. (bone phosphate of limey or more. When classifiers were introduced some of the fines that had escaped at the head of the washery and some of the minus 20-mesh material isolated during the rushing and formerly lost supplied the feed.

Jan 1, 1931

By C. N. Rosenecker

The power required to circulate a gas-solids suspension was determined using a centrifugal compressor and a closed system. The suspension consisted of 18- to 40-micron glass beads in a mixture of 89 percent N2 and 11 percent CO2 at 20 psig. Solids-to-gas (S/G) ratios w re O to 2.2 lb/lb; gas flow rates were l.2 to 2.5 lb/min. Power requirement was found to follow the relationship hp t = hp(. + l), where hp t = the total power, and hpg = the power required for pure gas.

Jan 1, 1967

By L. K. Weaver

The objective of this Bureau of Mines publication Is to present a nomograph that provides a fast, convenient method for estimating hydrocarbon lease bonus bids for offshore acreage in the Gulf of Mexico. Discounted cash flow analyses were computed from a model derived to show the costs necessary to explore, acquire, develop, produce, and abandon a 5,000-acre block of offshore acreage, and the estimated income from the sale of the hydrocarbons produced from the block. The range of the variables in the financial analyses used to construct the nomograph are prices of oil, $2.50 to $5.00; recoverable hydrocarbon reserves, 44,651,476 to 127,575,645 barrels; and discounted cash flow (DCF) rates of return, 5.0 to 57.2 percent. A total of 1,234 sets of DCF data were used to construct the nomograph. The range of bonus bids shown on the nomograph is from 2 to 90 million dollars ($400 to $18,000 per acre).

Jan 1, 1973

By B. W. Gandrud, G. T. Bator

The recent introduction of small coal jigs in Alabama to meet the needs of truck - mine operators for cheap and economical cleaning equipment marks another step in Alabama's pioneering record in the mechanical cleaning and preparation of coal . During the past 4 or 5 years a number of these small jigs , with capacity of 5 to 10 tons per hour , have been installed at Alabama truck mines and at a few truck mines in Illinois , Tennessee , and Pennsylvania . Most of the installations have been at mines that specialize in the production of domestic , stoker coal . This report describes three models of small jigs and includes performance data obtained recently on one of the models by the Bureau of Mines, United States Department of the Interior , in cooperation with the University of Alabama, Tuscaloosa , Ala . , for the purpose of comparing it with fullsize jigs on a performance basis . With literally hundreds of truck mines now in operation throughout the country , it has been assumed in preparing this report that there is widespread interest in the availability of small - scale inexpensive preparation equipment for use at such mines in the production of steam and domestic coal and in some instances coal for manufacture of coke . Practically none of the coal from Alabama truck mines is scld to coke - oven plants ; but in some sections of the country truck mines supply a considerable amount of coking coal, and the use of small, inexpensive washers at some of them might be very advantageous during the present war emergency from the standpoint of increasing pig - iron production through improvements in coke quality .

Aug 1, 1943

By Albert F. Baker

Techniques were developed and circuitry was assembled for measuring the total and volume resistances to the flow of electric current through solid specimens of anthracite. The two-, three-, and four-terminal test methods demonstrated the extreme sensitivity of resistivity to differences in anthracite characteristics and showed response to changes resulting from variations in structure, temperature, and moisture content.

Jan 1, 1966

By C. C. Blade

"This report on the properties of motor fuels sold through service stations ni the Unietd States is a continuation of a series of reports made in accordance with a cooperating agreement between the Coordinating Fuel Research (CRF) Committee of the Coordinating Research Council (CRC)3/ and the Bureau of Mines of the United States Department of the Interior. The first of these reports presented data on motor gasolines sold during the winter of 1935-36.4/ Further reports were issued describing motor gasolines sold during the succeeding summers and winters to and including the summer of 1941.4/ No reports were made on motor gasolines sold during the winter of 1941-42 and during the summer of 1942. However, starting with the winter of 1942-43, the semiannual reports were resumed.4/The present report presents analytical data for 1,381 samples, representing the products of approximately 75 companies. Most of the samples represented in this report were secured during July and the first half of August, 1945. As in previous surveys, the companies covered by the survey include both large and small suppliers. Conforming to former reports, the data cover three groups of samples – regular-price, premium-price, and third-grade gasolines.As the number of analyses submitted for samples of third-grade gasoline are not considered adequate to represent this type of motor fuel, data for the analyses have not been averaged, but the individual items are tabulated. The number of samples, items and brands comprising each group is as follows: Regular-price, 733 samples, 229 items, and 57 brands; premium-price, 504 samples, 197 items, and 56 brands; third-grade, 84 samples, 28 items and 12 brands. The meanings of these terms as sued in the surveys are as follows:"

Jan 1, 1946