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By L. R. Burdick, J. F. Barkley

The inherent heating value or the amount of heat that will be produced when a coal is completely burned is measured in British thermal units (B. t. u.) per pound of coal . This standard heat unit is the quantity of heat required to raise the temperature of 1 pound of water 1 °F . at about 60 °F . The amount of inherent heat is determined by burning a small quantity of the coal in a heat meter or calorimeter , which gives results in British thermal units . The exact manner of making this test is standardized by the American Society for Testing Materials.4/ The value so determined is the total heat developed by complete burning, with all the products of combustion cooled down to the temperature of the calorimeter . The calorimeter is kept at about room temperature . This total heat is sometimes called the " high" or gross heat value , because it includes the latent heat given up by the water vapor in the products of combustion when the vapor condenses to water in the calorimeter . The heat as measured is reported as the heat of combustion at constant volume , since the burning is carried out in a tightly closed calorimeter chamber whose volume does not change . In actual use , coal is usually burned in an open - end chamber at constant pressure , generally somewhere near atmospheric . As the heat of combustion of coal at constant pressure is very slightly higher than the heat of combustion at constant volume , it might be considered that the heat at constant pressure should be used as the standard reference base . For an ordinary eastern coal the heat at constant pressure is about 16 B. t . u. per pound higher than the heat at constant volume . Calorimeter corrections , ordinarily not considered , that could have been subtracted from the heating value before reporting , may amount to about as much . Hence , the value reported is apt to be more nearly the true heating value at constant pressure than at constant volume .

Dec 1, 1941

By J. H. Holden

The Federal Bureau of Mines is doing research and development work on a pressure-gasification pilot plant for producing synthesis gas directly from pulverized coal, oxygen, and steam. A pressure-gasification pilot plant has been constructed, and an investigation was made with the following basic objectives: 1. Determining the effect of varying pressure (75, 100, 150, and 300 p.s.i.g.), coal rate (400, 700, and 1,000 pounds per hour), and oxygen-to-coal ratio (8 to 11 std, c,f. per pound), on percentage of carbon gasified, oxygen and coal requirements per unit of CO + H2 produced, exit-gas temperature, and heat loss. The steam-to-coal ratio was maintained at approximately 0.3 pound per pound. 2. Development of a stabilized gasification zone or reaction space. 3. Improvement in operability of the pilot plant.

Jan 1, 1960

By C. C. Shale

Electrical resistivities for various coal ashes in air and in a nitrogen atmosphere are given over the range 100° to 1,500° F. Resistivity of low-carbon ash in air is very high at low temperature, rises to a maximum at about 250° F, decreases very rapidly with increasing temperature to about 800° F, then decreases gradually to approach an asymptote at 1,500° F. Resistivity of high-carbon ash in air follows this same general trend at values which are much lower and are proportional to the carbon content. After the carbon has been burned off, resistivity of the remaining ash approaches the high values corresponding to low-carbon ash of similar chemistry. Two factorial experiments show the effects of temperature, particle size, chemical content, and compressibility on the resistivities of four fly ashes of widely different chemical composition in the temperature range proposed for coal-fired turbines. Resistivities of all low-carbon ashes tested fall in the range 106 to 107 ohm cm at 1,500° F and should be removable by electrostatic precipitators. Ashes containing carbon in excess of about 8 percent, however, have low resistivity (as determined in nitrogen), especially at high temperatures. Therefore, high-carbon materials may not be collectable in precipitators because the resistivity is below the minimum value necessary for precipitation. Consequently, high carbon residues from partial combustion of coal probably could not be removed effectively at high temperatures.

Jan 1, 1968

By Stephen D. Hill

The Bureau of Mines devised and constructed a modified Knudsen effusion apparatus, permitting a constant measure of the weight of effusing vapor, to determine the equilibrium vapor pressure of metal halides at temperatures up to 1,200° K and over the pressure range 10-5 to 10-2 torr. The reliability of the apparatus was established by determining the vapor pressure of potassium chloride. After correcting for partial dimerization of the vapor, data obtained on solid KCl between 750° and 950° K can be expressed by the following equation:

Jan 1, 1966

By Bruce I. Thomas

As a part of the United States Department of the Interior program for developing natural resources in Alaska, the Bureau of Mines studied the tin-bearing gold-placer deposits in the Tofty area of the Hot Springs district in central Alaska. The principal objective of the Bureau's work was to obtain facts about the extent and character of the placer deposits (including tailing) to indicate the economic or strategic tin-production potential of the Tofty "tin belt." A secondary objective was to determine (if possible) the bedrock Source of the cassiterite and other minerals found in the placer deposits. The placer phase of the work was begun in July 1954 and was continued during the 1955 and 1956 field seasons. Extensions to, and connections between, known placer channels were sought by 82 churn-drill holes. The Bureau drilling did not expand the placer deposits beyond the limits established by drift-mining operations and by previous drilling done by private concerns.

Jan 1, 1957

By T. O. Glover

The Bureau of Mines surveyed unit trainloading and storage installations in the midwestern, eastern, and southeastern coalfields. Nine individual operations were studied in detail as a representative cross section of unit train operations in these areas. Of the nine operations studied, three were in Illinois, two in Kentucky, and one each in West Virginia, Tennessee, Ohio, and Pennsylvania. Information was obtained from coal producers, coal sale agencies, railroads, construction and equipment companies, and power companies.

Jan 1, 1970

By Joseph M. Pugliese

This work was done by the Bureau of Mines to provide quarry operators with an uncomplicated, first-approximation method for designing blast patterns, considering geologic structure, and to show the valid use of the technique by comparing drill and blast pattern dimensions used in the quarry with those determined by the presented method. The author visited 12 limestone and dolomite quarries in Ohio (Adam, Crawford, and Highland Counties), Wisconsin (Milwaukee, Racine, and Waukesha Counties), and Minnesota (Fillmore, Olmsted, and Wabasha Counties); observed the blasting practices; studied the major geologic features; and after discussion with the quarry managers, foremen, and blasters, compared the quarry blasting patterns with those as calculated by the empirical formulas (after R. L. Ash), with geologic structural considerations. When geologic structure such as bedding, jointing, folding, and caves, as well as explosive properties and field performance characteristics are accounted for in a manner suggested by the research, the presented empirical formulas may be used as a good first approximation. The included steps in planning a blast design and generalized blast patterns should be of help to the quarry operator. Design changes are recommended for those quarries where problems are occurring.

Jan 1, 1972

By X. N. Hu, X. Shi, V. Vallyathan, N. S. Dalai

"Although silicosis has been studied extensively, the mechanism is still not fully under stood. Experiments do provide evidence that the actions of unique properties of silica surface on the cell membrane are the starting point of silicotic processes. This paper summarizes literature on chemical properties of silica surface, and the effect of particle size on silica toxicity. This paper also discusses the ways in which silica dusts are thought to interact with the cell membrane, with emphasis on freshness, hydrogen bonding, and free-radical interactions.INTRODUCTIONSilicosis is a debilitating pulmonary disease that afflicts persons (miners, foundry workers, ceramic workers, heavy construction workers, etc.) who chronically inhale silica-containing dusts (Schepers, 1960; Silicosis and Silicate Disease Committee, 1988). Since silica is second only to oxygen in weight percentage of the earth's crust (about 28%) and is found in an enormous diversity of minerals, it is natural that silicosis is one of the Major industrial health hazards all over the world. Although silicosis has been studied extensively, the mechanism by which the dusts exert their toxic actions on cells and the processes by which these-actions progress to fibrogenesis are still poorly understood. The biological characteristics of the dusts are largely unknown, although it is suggested that the dust size, shape, surface charge, roughness, surface chemical composition, trace metal content, and crystallinity; dose of silica in the ambient air of the workplace; duration of exposure; genetic variation in exposed sub¬jects; personal respiratory patterns; and presence of any coexisting dis¬ease (such as tuberculosis or rheumatoid arthritis) all influence the ex¬pression of silicosis (Koskinen et al., 1983; Noweir et al., 1980; Raask and Schilling, 1980; Reiser and Last, 1979; Thorne et al., 1985; Wolff et al., 1981). The actual biochemical mechanisms through which these factors operate are still unclear. However, the experiments do provide evidence that the actions of certain unique properties of silica surface on the cell membrane are the starting point of the silicotic process (Allison et al., 1966; Allison and Harrow, 1971; Bateman et al., 1982; Marks, 1957; Parazzi et al., 1968; Reiser and Last, 1979; Summerton et al., 1977). This article summarizes literature on chemical properties of silica dusts and how silica dusts are thought to interact with the cell membrane, with emphasis on hydrogen bonding and free-radical interactions."

Jan 1, 1989

By L. B. Pankratz

Thermodynamic data on the elements, oxides, sulfides, halides, and selected hydrides, carbides, nitrides, carbonates, sulfates, silicates, and miscellaneous compounds were reviewed, evaluated, and compiled at the Bureau of Mines. Values for CP°, S°, H° -H°298, ?Hf°, and ?Gf° are given in tabular form. A brief thermodynamic background and a number of examples and applications are presented.

Jan 1, 1984

By H. A. Doerner

"During the year which has passed since the last progress report on reduction of zinc by natural gas,3 the laboratory experiments on this investigation have been completed. In this concluding report, the whole subject will be reviewed and additional data presented.Chemical ReactionsIn a thermodynamic study of zinc smelting, Maier 4 discussed the use of methane for reducing zinc oxide, and predicted equilibria at various temperatures for the sore important reactions. The study has been extended to include the following list.Maier predicted that 870°C. would be the critical temperature above which reaction (1) would take precedence over reaction (2) and that reaction (1) at equilibria would be substantially complete at or above 927°C. A subsequent papers described experimental verification of these predictions and gave data on reaction rates under various conditions.It methane is passed through a heated bed of zinc oxide at a low enough rate reactions (1), (3), and (4) reach an equilibrium which can be expressed by reaction (10). The equilibrium concentrations for the products of this reaction in the temperature range 900° to 1100°C. were calculated by applying the thermodynamic constants to the stoichiometric relations. 6 The results of these calculations are listed in table 1 and shown graphically in figures 1, A and B. These data have major importance, and experimental work has shown that they are subtantially correct."

Dec 1, 1934

By Stephen Krickovic

A degasification experiment was conducted in a Pocahontas No. 3 coalbed mine in Virginia. It involved (1) drilling holes in the coalbed in the out-side headings of a set of five being developed in virgin area, and (2) con-ducting a methane emission rate study as mining progressed and additional holes were drilled. Degasification from all drill holes except the longest in each of the outside headings and the first three drilled (excluding the in-situ pressure hole), was erratic and inconsequential in methane emission rates. The two longest holes liberated 66 and 79 cfm of methane, which is significant for the coalbed, but such quantity lasted a relatively short time; the first three were uniform but low in methane emission.

Jan 1, 1972

By Edward G. Cunney

Track in underground bituminous coal mines was investigated and technology was taken from other industries in order to obtain information on conditions that impair the safety and efficiency of the track and to develop guidelines and useful information on the construction, inspection and maintenance of mine track. Volume 1 contains information on the investigations, observed track conditions, useful technology from railroads and other industries, derivations of track condition descriptors and limits, conclusions, and recommendations. Volume 2, Guidelines, contains recommended standards and practices for mine track. It includes the relation of track conditions to safe speeds; descriptions and limits for measurable track features, such as gage; descriptions of conditions for track components that are normally not measurable, such as subbase soils; construction requirements and techniques; inspection requirements and methods; and methods for managing and performing track maintenance work. It does not repeat the summary or? derivations. Volume 3, Inspection Handbook, summarizes recommended standards and procedures from Volume II and provides related information for ready reference by inspectors in the mines. As a research product to be used in mines, it does not repeat the summary, derivations or references.

Jan 1, 1977

By Fay B. Dillard

This Bureau of Mines report reviews the disposition of natural gas as delivered to industrial consumers via main line sales. Salient information on main line, or direct, natural gas sales to industrial users is presented by State) standard industrial classification code (SIC) revenue, and type of sales for the years 1968 through 1973.

Jan 1, 1975

By W. C. McBee

A family of modified-sulfur cements has been developed by the Bureau of Mines for the preparation of construction materials with improved properties. Various types of sulfur cements were prepared by reacting sulfur with mixtures of dicyclopentadiene (DCPD) and oligomers of cyclopentadiene (CPD). Durable cements were prepared with structural characteristics ranging from rigid to flexible. These cements were used to prepare corrosion-resistant materials for use in a wide variety of industrial applications where resistance to acidic and salt conditions is needed. These materials were prepared as rigid concretes, flexible pavings, spray coatings, and grouts. Production of modified-sulfur cements in a commercial-size plant was demonstrated.

Jan 1, 1981

By J. D. Davis

On May 15, 1936, Congress authorized the Bureau of Mines to conduct certain studies, experiments, and investigations of subbituminous coal and lignite .4/ Appropriations were made in July 1937, and since that date an active investigation has been underway to complete the provisions of the act. Part of the investigation has included a comprehensive survey of the known properties of the lower-rank non-coking coals, and provisions were made to obtain more data on certain varieties. In line with this plan, a typically subbituminous coal was selected for an extended series o tests in the standard Bureau of Mines-American Gas Association unit,5/ at the Central Experiment Station. This particular noncaking coal was the first one of its rank that ha& been tested in the apparatus; for this reason the results are of particular interest because the testing apparatus was originally designed for use in studying the coke- and gas-making properties of coking coals. The test as described below has been developed by the Bureau of Mines since 1927 through a cooperative agreement with the American Gas Association.6/ Ninety to 180 pounds of coal is heated in a circular retort, 13 to 18 inches in diameter, at wall. temperatures ranging from 540°C. to 1,110°C. in 100°C. steps. All products axe collected and measured; their physical and chemical properties axe then carefully determined to ascertain the gas- and coke-making properties of the coal.

Jan 1, 1939

By Michael G. Zabetakis, Glenn H. Damon, Joseph A. Herickes

The flammability and explosibility of unsymmetrical dimethylhydrazine ( UDMH ) were investigated by the Federal Bureau of Mines to evaluate hazards associated with commercial application of this material as a missile fuel . This program included the following determinations : 1. Temperature limits of flammability in air at one atmosphere pressure ; 2. limits of flammability at selected elevated temperatures and pressures ; 3. 4 . 5. spontaneous ignition temperature in air at one atmosphere and at 200 pressure per square inch gage ( p.s.i.g. ) initial pressure ; spontaneous decomposition temperatures in nitrogen at one atmosphere and at 200 p.s.i.g .; shock sensitivity over a temperature range from about ( ca. ) 25 ° to 50 ° C .; 6. shock sensitivity of reference propellants ( hydrazine , nitromethane , methyl acetylene , etc. ) ; 7 . shock sensitivity of UDMH plus small amounts of selected metal catalysts . Part of the corresponding data was obtained for a mixture of unsymmetrical - dimethylhydrazine and diethylenetriamine ( U - DETA) .

Jul 1, 1960

By Paul V. Mullins

Review and evaluation of all available data on the vapor pressure of car-bon dioxide at the ice point, including previously unpublished results obtained by the Bureau of Mines, are presented. Suggested corrections and adjustments to all the data yield an average value of 26,136.4 mm mercury. Indicated agreement is within plus 1 part in 8,000 to minus 1 part in 11,000. A novel pressure bomb in which a sample of pure carbon dioxide is placed and sealed by a diaphragm fluid separator and its use as a reference pressure standard for extended and repeated use in the calibration of deadweight gages is described.

Jan 1, 1966

By A. A. Berk

In the course of a study of the formation of external deposits on tubes in water-tube boilers it became desirable to determine the sulfur dioxide (SO2) and sulfur trioxide (SO3) in the Due gases. Determinations made by the A.S.M.E. method for SO2 and SO3 in gaseous products of combustion did not give accurate results. It was found that minute quantities of copper, present in the flue gases from the coal in use, caused oxidation of sulfite in the absorption bottle and that the carbon dioxide (CO2) in the flue gases caused high values for SO2. The A.S.M.E. test procedure was revised to prevent oxidation of sulfite in the absorption bottle and to allow for the effect of CO2; subsequent analyses of flue gases produced reliable results. The revised procedure is described.

Jan 1, 1950

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 George S. Rice

A novel method of extinguishing a mine fire in a stowed or gob-filled area by employing liquid carbon dioxide under high pressure eras used recently with success at the President (Prasident) coal mine, Bochum, Germany, as reported by P. Cabolet in Gluckauf (Apr. 24, 1937, p. 393) The use of carbon dioxide gas as a fire-fighting agent in surface plants and in ships is now general practice in the United. States, but when it has been tried for extinguishing fires in mines in large areas more or less confined by stoppings it has not been successful. Examples of the latter method of attempting to fight mine fires are given in Bureau of Mines Bulletin 229, Fifty-Nine Coal-Mine Fires; How They Were Fought and That They Teach, by G. S. Rice, J. VT. Paul, and 14. VT. von Bernewitz (1927). The reason for its nonsuccess may be either that the stoppings are not tight or that the roof and pillars are more or less fissured and enough air passes into the area to sustain a slow fire, whether of spontaneous origin or produced by gas explosion or other source of ignition.

Jan 1, 1937