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By Michael G. Zabetakis, Israel Liebman, Henry E. Perlee

Flammability studies conducted to date on stratified methane - air and pentane - air mixtures in air indicate that location and extent of a flammable layer are affected by molecular diffusion , gas motion , and propagation of flame . In initially quiescent mixtures , the lower limit - of - flammability zone may be determined by assuming molecular diffusion alone governs mixing rate . The upper limit - of - flammability zone can be predicted in this manner only for stratified layers with small concentration gradients ( less than 0.2 volumepercent per inch ) ; where large concentration gradients are encountered ( for example , as much as 30 volume - percent per inch ) , the initial - mixture methane concentrations that yield flammable mixtures are larger than anticipated . Flames propagating through heterogeneous quiescent methane - air atmospheres in the direction of the concentration gradient exhibit flame speeds at any point that corresponds to the flame speed of the homogeneous gas mixture having the same gas composition as that of the point in the heterogeneous system . In flowing mixtures with large concentration gradients , the degree of mixing prior to ignition does not appear to affect the flame velocity and emitted radiation appreciably in a 6.5 - ft - diameter gallery .

Jan 1, 1964

By C. P. Fang, V. A. Marple, K. L. Rubow

"Studies of the flow fields and particle impaction characteristics are more complicated in multi-nozzle impactors than in single-nozzle impactors, since the jets of air must penetrate cross-flowing air to impinge on the impaction plate. Results of heat and mass transfer analysis are employed to describe the cross-flow pattern in multi-nozzle impactors. A cross-flow parameter has been derived to predict the deflection of the air jet by the cross-flow. This parameter is expressed as a function of the geometric parameters for the multi-nozzle impactor. DnN 4D,, where N is the number of nozzles, Dn the nozzle diameter and D, the nozzle cluster diameter. Empirical particle collection data show that multi-nozzle impactors operate satisfactorily, if the cross-flow parameter is less than a critical value of 1.2. Impactors operating with a cross-flow parameter larger than this critical value are shown to possess poor particle collection characteristics.Inertial impactors of many designs have been used for sampling aerosol particles. Impactors can be single stage, consisting of a nozzle and an impaction plate, or a cascade impactor with several stages in series. The simplest design for a stage is a single nozzle with a flat impaction plate. However, many designs use stages with multiple nozzles of identical size, which allows for compact impactors to be designed at rather substantial flow rates and moderate pressure drops.Nearly all of the theoretical work, and much of the experimental work, has been performed on single-nozzle impactors. The results of single-nozzle impactor analysis are often applied to multiple-nozzle impactors, which are assumed to be a group of individual nozzles, each operating as though they were single nozzles. However, an important fact is often ignored: the interaction of flow from adjacent nozzles can change not only the fluid mechanics in the impaction region, but also the locations of the jet stagnation points, and the impaction characteristics of each nozzle.The effect of multiple nozzles on the particle collection characteristics of impactors has been studied by a few investigators. May (1964), Fletch et al. (1967), Friedrichs (1968), and Vaughan (1986) reported that the quantity of particles in deposits of nozzles in the first two stages of the Andersen multi-nozzle cascade impactor were not equal. The inner deposits appeared to contain fewer particles than the outer ones. However, Vaughan (1986) in addition showed that many of the deposits in the outer three rows were missing on the first stage, even though the outer deposits that were present were larger than the inner deposits.May (1964) conducted experiments and explained the phenomenon of smaller deposits near the center than near the edge. He noted that in Andersen cascade impactors the air issuing from the nozzles moves radially outward along the narrow channel between the nozzle plate and the impaction plate. This flow at 28.31min -1 created a pressure difference of about 1 mm water between the inner and outer sections of the channel. The effect was most pronounced in the first two stages, where the pressure drop across the nozzles was also about 1 mm water. Here, the flow velocities in the nozzles, and hence the deposits, were smallest at the center and increased toward the periphery of the impaction plate. since the pressure drop across the nozzles was the smallest at the center and a maximum at the periphery. This effect was negligible in the lower stages because of a larger pressure drop across the nozzles. According to May (1964), this effect could be eliminated by increasing the nozzle-to-impaction-plate distance to three nozzle diameters and improving the nozzle arrangement to allow air flow to escape to the periphery more easily."

Mar 1, 1992

By R. G. Knickerbocker, A. L. Fox, J. Koster, P. R. Perry

"During the past several years, alunite from the Marysvale (Utah) region has been the subject of investigation by the Electrometallurgical Section of the Bureau of Mines. The nature and occurrence of this mineral, with considerable data on the Utah deposits, together with a number of results of preliminary experiments, have been given in a previous report. 6/ The geology of the Marysvale region has been reviewed recently. 7/The present paper reports the results obtained by a method involving the sintering of alunite with boric acid and subsequent treatment of the sinter to produce alumina and potassium sulphate.The preliminary work just mentioned had given indications of the separation of sulphate salts high in potassium from fusions of alunite with borax glass.During the course of further work along those lines, fusions of boric acid and alunite were tried. No separation of salts was obtained, but it was observed that rather complete removal of so3 from the alunite occurred and that the sinter could be leached with water to give a solution contain¬ing most of the potash and a residue containing most of the alumina. The reaction that takes place can probably be written 8/:"

Mar 1, 1939

By R. B. Schluter

The objective of this Bureau of Mines investigation was to determine the effects of adding manganese compounds and ores to iron ore pellets. Manganese dioxide, carbonate, sulfate and chloride, plus six manganiferous ores from the Minnesota Cuyuna Range were tested as additives to increase the manganese content of iron ore pellets. One to 5 percent manganese, as a compound or ore, was added to five magnetite concentrates and one hematite concentrate. These concentrates were ballad, indurated (1,300° C), and tested for reducibility. Manganese sulfate and chloride were unsatisfactory additives causing cracking and degradation of the pellets during reduction. Manganese dioxide, carbonate, and the ores were satisfactory additives. The additives increased pellet compression strengths with a corresponding loss of reducibility, as compared to the pellets without manganese additions. The changes in compression strengths and reducibility were caused by the formation of Jacobite spinel and slag within the pellets. However, when the induration temperature was lowered from 1,300° to 1,200° C the reducibility and compression strengths were comparable to the pellets without manganese additions indurated at 1,300° C.

Jan 1, 1974

By J. C. Edwards

To have the capability to predict the development of localized spontaneous heating within a porous coalbed that is subjected to forced air ventilation or in an otherwise quiescent environment in which buoyancy develops, the Bureau of Mines developed three time-dependent mathematical models, which were used to calculate the temperature increase associated with chemisorption of oxygen by the coal. In each model, spontaneous heating is driven by an Arrhenius first-order reaction between the oxygen and coal. Two models are two-dimensional, and one is one-dimensional. In the first two-dimensional model, a constant-velocity forced convection airflow is specified; and in the other, buoyant flow is allowed to develop in the absence of forced convection. The third model evaluates the airflow from Darcy's law and a specification of the pressure at the surface of a one-dimensional porous coalbed. Numerical computations demonstrated how each model could be used to predict the onset of spontaneous heating when the porous coalbed was subjected to constraints of an imposed internal heat source or a high temperature airflow. The effects of particle size and coalbed compaction upon spontaneous heating were examined with the third model.

Jan 1, 1990

By T. E. Swigart

In the production of oil end gas, engineering methods have been applied less than in any other branch of the oil industry. While refineries, gasoline plants, pipe-line and other transportation systems, and even drilling wells to a great extent, take advantage of engineering skill, the tendency has been to assume that the handling of producing wells is merely a mechanical and routine matter. At present few companies employ engineers to study oil and gas production methods with a view of increasing the general efficiency of recovery, but in vie, of the advancement in other lines of the petroleum industry by the application of engineering principles, does it not seem likely that the production branch may benefit also by engineering studies? Engineering applied to the handling of producing wells falls under two general headings, - first, the efficient handling of wells from the time of their inception in order to obtain the greatest possible ultimate production, and, second, the rehabilitation of old properties that have been handled carelessly in their early lives. To date, the engineering work that has been done on oil production problems falls mostly in the second class. For example, the use of vacuum and the application of compressed air have proved successful in some instances in stimulating wells of low gas pressure. These methods are costly to apply and are adapted to small wells in which the gas is almost exhausted, or in which the original gas pressure is negligible. The experiments described in this paper fall under the first heading, as they were made with an idea of learning toe probable extent to which the gas production of an oil well can be curtailed while gas in the sand is still plentiful, and thus saved for doing work during the later period of a well's life. Because of the scope of the experiments, this paper does not include a discussion of back pressure on flowing wells or for purposes other than cutting down the gas produced with each barrel of oil.

Jan 1, 1922

By G. W. Jones, F. E. Scott

"INTRODUCTION During the last war, considerable attention was given to the search for materials or combinations of materials for use as expelling agents for aerosols in the well-known ""aerosol bomb."" These materials must be free of fire and explosion hazards under normal conditions of use.In cooperation with the Department of Agriculture and other Federal agencies interested in the work, the Bureau of Mines carried out a laboratory investigation on the inflammability of- dimethyl ether-dichlorodifluoromethane air mixtures. 4/The method of investigation was essentially the same as that used in a similar investigation dealing with the inflammability of propane-butane-dichlorodifluoromethane mixtures. 4/SOURCE OF MATERIALSThe dichlorodifluoromethane (commonly known as freon-12) and the dimethyl ether were supplied by Dr. Lyle D. Goodhue., U. S. Department of Agriculture, Beltsville, Md. It was reported that the freon-12 was manufactured by the Kinetic Chemical Co. Wilmington, Del., and the dimethyl ether by the Carbide & Carbon Chemicals Corp., Charleston, W. Va..The materials were obtained in small metal cylinders and were used as received. Before using, the cylinders mere placed in an upright position, and 5 to 6 liters of the gas was released from each cylinder to the atmosphere to remove any trapped air that may have been introduced when the cylinders were filled."

Sep 1, 1947

By S. L. May

Tantalum and columbium can be extracted from several of their ores or concentrates by chlorination procedures. Direct chlorination of high-grade minerals in the presence of carbon at temperatures between 500° and 800° C will extract up to 99 percent of the tantalum and columbium. Metallurgical beneficiation of low-grade source materials by carbothermic reduction produces a ferroalloy that is amenable to chlorination at a temperature of 500° C. Over 90 percent of the tantalum and columbium can be recovered.

Jan 1, 1965

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 Jr. Karr

The Bureau of Mines studied the influence of carbonization method, temperature, and carrier gas on the composition of eight different low-temperature tars produced from a Colorado subbituminous coal. A fluidized bed was compared with an entrained bed, temperature was varied from 500° C to 650° C, and external heating using recycle gas as the carrier gas was compared with internal heating using oxygen-containing gas. The entrained bed yielded significantly more m-cresol and m-ethylphenol, indicating that thermodynamic equilibrium was more nearly approached in the system. Increasing the temperature greatly increased the yield of benzenes and naphthalenes, while paraffins, olefins, and total tar acids were reduced. Using oxygen in the carrier gas decreased the yield of low-boiling phenols and increased that of paraffins and olefins at 650° C.

Jan 1, 1966

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-million-standard-cubic-foot-per-day, high-Btu gas plant. The annual tonnage for the Eastern province mine is 4.8 million tons; for the Interior province mine, 6.72 million 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 December 6, 1974, under the terms of the Bituminous Wage Agreement of 1974, and costs for material and equipment are based on 1975 indexes. Initial capital investment varies: $65,137,900 for the 4.8-million-ton-per-year (MM tpy) mine in the Eastern province, $78,514,600 for the 6.72-MM-tpy mine in the Interior province, and $42,050,100 for the 9.2-MM-tpy mine in the Northern Great Plains province. Total capital investments for the Eastern province mine, the Interior province mine, and the Northern Great Plains province mine are $86,969,900, $109,378,500, and $78,543,500, respectively. Corresponding selling prices for the coal, per ton, are $6.94, $6.03, and $3.39, assuming a 15-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, 1976

By W. A. Jacob, E. W. Dean

The Pittsburgh petroleum laboratory of the Bureau of lines has recently developed an improved method for the determination of water in pctroleum emulsions. It has been described in detail in an article entitled "A convenient method for the determination of water in petroloum and other organic emulsions" by E. W. Dean and D. D. Stark (Jour. Ind., and Enc. Chem. Vol. 12, ſay, 1920, page 436). It is essentially a modification of the familiar procedure of "distillation with an iniscible solvent", the improvement consisting in the use of apparatus that is rºck more convenient than any previously employed. The method has been used with marked success in the Bureau's laboratories for a period of about a year and has also been tried with equal satisfaction by a number of other laboratories. It has been most extensively employed for determining the water content of heavy fuel oils but has been applied also to several other types of emulsions, including shale oils, tars derived from coal, greases, and mixtures of powdered coal, oil and water. The Bureau has received a number of requests for information regarding commercial sources for the apparatus used, and having been assured of the value of the method, has taken steps to render it available for general use. - The equipment is, with the exception of two items, made of parts that are obtainable from the ordinary stock of chemical supply houses. The two exceptions are (1) the so-called "distilling tube receiver" and (2) the electric heater. The former is an essential part of the equipment; the latter is a convenient ac cessory but it can if necessary be roplaced by a gas burner. Efforts on the part of the Bureau staff to ronder these two items of apparatus available for purchase from supply houses, or for production by the user are hero described.

Sep 1, 1920

Although early Spanish settlers used coal several centuries ago, significant commercial coal mining in New Mexico began in 1861, when the U.S. Army opened a mine to supply Fort Craig. Since then, coal from the state has been used to fuel railroads, lead and copper smelters, and other local industry. In recent years, lower-cost strip mining methods and an increased demand for coal by electric utilities in the Southwest have caused an increase in New Mexico coal production. The coal-bearing regions of New Mexico underlie about 25,000 square miles or20.6 percent of the total area of the state. However, the majority of coal-bearing regions lie under Indian lands that are regulated by the Office of Surface Mining (see Navajo and Hopi data on pages 72-75). Today, most of the coal produced in New Mexico comes from the San Juan Basin in the northwest part of the state and the Raton Area in the north central part. New Mexico's reserves are estimated to be 4.6 billion tons, about one percent of the national reserve. New Mexico's permanent regulatory program was conditionally approved December 3 1, 1980. Its Abandoned Mine Lands Program was approved July 17,198 1.

Jan 1, 1992

By R. V. Ramani, C. B. Manula, A. Owili-Eger

PART 1 THE INPUT AND OUTPUT DATA AND THE MINE SCHEMATIC SHOWING THE FLOWS FROM COMPUTER SOLUTIONS FOR APPLICATION I

Jan 1, 1975

By F. S. Crawford

Interesting data on electric blasting and sinking of the Montreal No. 5 shaft of the Montreal Mining Co., Montreal, Wis., were obtained during the sinking of the last 877 feet of this shaft. Several unusual features and safety practices are also to be found in the Montreal mine. The Montreal shaft was sunk 2,156 feet from August 16, 1921, to May 1, 1924, and 877 feet from October, 1927, to June, 1928. The first section of the shaft was supported with steel sets spaced 5 feet on centers; and instead of lagging the walls were covered with three-eighths of an inch of gunite where Greenstone was encountered, and where quartz-slate was found (from the surface to the 12th level) the walls were lagged with tamarack lath treated with carbolineum, a preservative.

Jan 1, 1929

By Sara J. Davenport

Hydrogen sulfite has been listed (1)3/ as a possible hazard in 50 occupations, many of which are in the mineral industries. The effects of its occurrence in the petroleum industry made themselves felt more than two decades ago, resulting in a comprehensive study (2) of the toxic gases from Mexican and other high-sulfur petroleum products. The mining industry, likewise, has had cause to guard against this gas. Enough hydrogen sulfide has been found in coal and some noncoal mines during normal operations to cause severe eye irritation, some serious illness, end even fatalities. It is usually a product of the decomposition of sulfur compounds and may be produced by burning explosives containing sulfur; the gas in harmful qauntities is formed by the use of block blasting powder or by the use of dynamite in blasting sulfide ores. Hydrogen sulfide is readily soluble in water, and enough may be released from water streams in coal and noncoal mining to cause fatal poisoning it is found sometimes in stagnant water underground, particularly where ventilation currents are absent, and great care must be exercised when accumulations of such waters are disturbed, as exposure to comparatively low concentrations of the gas evolved therefrom has caused fatal accidents.

Jan 1, 1945

By Mark Sheppard

This paper is the second of a series recording the results of tests made at various quarries throughout the United States to determine, (1) the relation between the size gradation of feed to, and product from, primary crushers; (2) the particle shape of crushed product; (3) the differences in gradation and particle shape produced by different tries of primary crushers; and ( 4) the differences in gradation and particle shape caused by crushing different kinds of stone. Primary crushing has received comparatively little attention in the technical literature in spite of tine fact that the design of the whole crushing plant should be correlated to the performance of the primary crusher.

Jan 1, 1938

By J. T. McCartney

In an effort to correlate the size of pyrite particles in coal and coal-particle association with the removal of pyrite before burning, the Bureau of Mines conducted a study of 61 coals presently being used for electric power production. The results were obtained by visual microscopic studies of polished briquets of minus l4-mesh samples. Mean pyrite particle sizes ranged from 20 to 400 microns and proportions of pyrite contained in coal particles to an extent greater than 50 percent by volume (estimated) ranged from 20 to 95 percent. These parameters were correlated with reductions in pyrite accomplished by float-sink tests at 1.60 sp gr on 14-mesh, 3/8-inch, and 1-1/2-inch samples. The correlation coefficients between pyrite removal and mean pyrite particle size were 0.89, 0.84, and 0.79, respectively, for these samples. Correlation coefficients between pyrite removal and coal-pyrite association parameter were 0.92, 0090, and 0.85, respectively. It is apparent that extent of pyrite removal can be fairly well predicted from microscopic analysis.

Jan 1, 1969

By G. A. Crowder

Far infrared spectra, most of them in the region 15-200 microns and for both the liquid or solution state and for the vapor state, were obtained for twenty-seven compounds.

Jan 1, 1965

By A. T. Coumbe

This compilation of statistics covering competitive fuels consumed for heating of residential and commercial buildings is in response to numerous requests for data of this nature to show the relative changes in the demands for the different fuels in recent years. The figures presented cover the amounts of various fuels ant electric energy reported as used for heating dwellings and commercial buildings. However, the totals for gaseous fuels and electricity necessarily include amounts consumed for both cooking and lighting purposes, as these associated household uses could not be readily broken out. [ ] SOURCES OF FUEL AND POWER STATISTICS Liquid fuel: Mineral Market Reports of the Bureau of Mines covering annual Pales of fuel oil and kerosine. The fuel oil figures include grades 1 to h, reported as sold for space heating. Kerosine and grade 1 fuel oil delivered as range oil ore also included. Gaseous fuel: "Gas Facts" published by the Bureau of statistics of the American Gas Association. Thin source was used as It is believed that the data shown are representative of the actual market

Jan 1, 1953