Search Documents

By J. E. Schiller

The Bureau of Mines has investigated the surface charge of amphibole asbestos fibers and nonasbestiform cleavage fragments, as part of the Bureau's fundamental studies to provide new knowledge on the physical and chemical properties of the amphibole minerals. Microelectrophoresis was used to measure the electrophoretic mobilities, in water, of particles from six asbesti-from amphiboles and seven nonasbestiform amphiboles over the pH range of 5 through 9. The particles generally ranged in size from 2 to 5 µm wide by 10 to 30 µm long. The isoelectric point was determined for four of the minerals, and values were found to be between pH 3.5 and pH 5. The minerals studied had zeta potentials that generally ranged from -25 to -so mv in neutral solution. Attachment of colloidal positively charged AgI was also studied as a means of determining surface charge. Scanning electron microscopy of amphibole particles that had been in contact with aqueous AgI showed equal attachment of AgI to asbestos fibers and to cleavage fragments; the extent of AgI coating was the same for both. The electrophoretic mobilities of asbestos fibers were essentially the same as those of elongated cleavage fragments of the same aspect ratio (particle length divided by width). Blocky particles from both asbestiform and nonasbestiform specimens had lower mobilities.

Jan 1, 1980

By M. M. Myers

"Importance pf the small stone problem.Profitable disposal of limestone too small for making lime in the shaft kiln, is one of the most urgent problems in the lime industry. Reports received by the Bureau of Mines from 31 quarries show that the proportion of small stone varies from 2 to 40 per cent, averaging 18 per cent of gross pro¬duction, Modern methods of heavy blasting, and the use of crushers in large quarries tend to increase the proportion of small stone above that produced in early days when light blasting and hand sledging were almost universally used. There is also a growing movement toward underground operation of lime deposits, a method which in general produces a greater proportion of fines than is encountered in open-pit work. Thus the small stone problem is of growing importance, and demands the attention of every progressive lime producer. As the problem is of almost universal interest, it is urgently desired that every operator who reads this report will contribute from his knowledge or experience, answers to the questions on the final sheet.There are several markets in which small stone may be sold but in these markets the competition is generally keen and the prices low. The lime producer's chief product is lime, he understands its manufacture and marketing, and brings him a greater return than can be obtained from most limestone by-products. For these reasons it is evident that the conversion of small into lime is the nest desirable means of disposal."

Apr 1, 1924

By Oliver Bowles

Since 1922 when the Bureau of Mines issued a report2 covering the slate industry in detail, changes in technology have taken place which have an important bearing on the industry. The present paper comprises a record of these changes. Though the value of slate, for roofing, structural, blackboard, sanitary, and electrical uses is generally recognized, it has many competitors. To meet this constantly increasing competition producers are promoting economies in manufacture, and improving processes, thereby lessening costs of production, and are placing on the market products of the highest possible quality, thus creating satisfaction and confidence on the part of the user. This endeavor to place the industry on a better basis, both as regards processes and products, is shown in the recent developments in technology which are presented herein. Valuable assistance in obtaining data for this paper was given by W. S. Hays, secretary of the National Slate Association, N. M. Male, president of the National Slate Association, and Robert Notvest, consulting engineer, Cleveland, O.

Jan 1, 1926

By G. W. Jones

[A survey of the Ii terature reJ.l....ting to iE;li tion temperatures of acet-ylene-air and acetylene-oxygen mixtures reveals rather '.'fide disagreement in the reported results. In SO!':1e instances the i ition temperatures of acet?-ylene-air mixtures were reported to be lower than those of acetylene-oTjgan mixtlU'es, which is contrary to experience 'tri th other combustibles. ':10 clea.r up some of t!le reported discrepancies, the authorn have icvestigated the igni tion temperatures of acetylene both in air anri oxygen, and their results are presented in this report.]

Jan 1, 1941

By E. J. Harris

Data obtained from mine ventilation pressure and quantity surveys are required to accurately diagnose ventilation problems, project future air quantity needs, and to locate conditions adversely affecting the efficiency of a mine ventilation system. A method for making mine ventilation pressure surveys with aneroid altimeters was presented in Bureau of Mines Information Circular 7809, and a description of field calculation technique is presented. This report supplements Information Circular 7809 by developing the information obtained during a mine ventilation pressure survey into a single equation suitable, with appropriate modification, for use with desk-top calculators and digital computers. The equation can be used to calculate the ventilation pres sure from the base station to any underground station, or between any two underground stations, and can be programed for semiautomatic sequential calculation using a desk-top calculator. An example of application to a programed desk-top calculator is provided in the appendix.

Jan 1, 1973

By Rudolf E. Greuer, Linneas W. Laage, Xinton Chang

MFIRE is useful for the analysis of ventilation networks under thermal and mechanical influence MFIRE simu¬lates a mine&apos;s ventilation system and its response to altered ventilation parameters, external influences, and internal influences Extensive output enables detailed quantitative analysis of the effects of the proposed alteration on the ventilation system MFIRE was written in FORTRAN 77 and compiled with Microsoft° FORTRAN for the Intel 8086-8088 central processing units The source code is listed in appendix A for users who wish to modify the source code for operation on other computers MFIRE MODIFICATIONS OF MTU-BOM CODE The program described in Bureau of Mines Informa¬tion Circular 8901 has become known as the MTU-BOM codes MFIRE is an evolutionary product of the MTU¬BOM code with major improvements and enhancements 6 For users previously familiar with the MTU-BOM code, the following is a listing of the major improvements and enhancements incorporated by MFIRE 1 The length of an airway is an input value, LA The elevation difference of the airway is calculated from the elevation input, Z, in both programs It is possible for a data file to describe an airway that is shorter than its el¬evation difference The MTU-BOM code does not check for this error and uses the values of LA and Z This does not cause a computational problem, only a simulation problem MFIRE issues a warning message for this case, and the airway length is made equal to the elevation dif¬ference if LA is less than Z 2 To evaluate rock temperatures (average wall surface temperature of airway before a fire), it is assumed that the air temperature at an airway entrance is equal to the air temperature at the airway starting junction, and that the air temperature at the airway exit is equal to the air tem¬perature at the exit junction. The MTU-BOM code follows this assumption in all cases When a rock temperature of less than 0° F is calculated, an average temperature is used to represent the rock temperature of the airway MFIRE uses the same principle, except the consideration of unlikely rock temperatures When the exit junction of an airway is the atmosphere (a fixed condition junction), the air tempera¬ture at the exit is made equal to the air temperature at the airway beginning If an unlikely value of wall temperature (<0° F or > 150° F) results from calculations, a message is issued and the rock temperature is set equal to the air temperature at the airway exit The program user can always input rock temperature (TROCK) for an airway to override the calculated value. 3 MFIRE allows use of an optional reference airflow rate to define and limit the heat generation of a fire source This allows the simulation model to more closely resemble a real fire and to improve simulation conver¬gence Heat generation corresponds, but is not linearly related to airflow rates reaching the fire In the simula¬tion, heat generation is calculated from oxygen consump¬tion and is directly related to the variable incoming airflow Use of this optional reference airflow rate allows the heat generation to vary, but in a damped, user defined manner When the airflow rate passing through a fire source is equal to its reference airflow rate, the data items describ¬ing the fire source are not modified If the airflow rate is lower or higher than its reference airflow rate, the data items used to define the fire source are modified according to the following equations

Jan 1, 1990

By William D. Monaghan, Thomas H. Dubaniewicz, Kenneth L. Cashdollar

Emerging laser technologies are quickly gaining acceptance in the industrial workplace. Besides the risk of human exposure, one safety concern with the more intense lasers is the potential for ignition of flammable gases, vapors, dusts, fibers, or flyings often found in hazardous (classified) industrial settings. In underground coal mines, lasers are being considered for remote measurement of explosive methane gas. Current federal safety regulations for underground mines contain no specific guidance for evaluating the safety of optoelectronic components such as diode lasers. The National Institute for Occupational Safety and Health is conducting research to help provide a scientific basis for developing appropriate safety guidelines for optical equipment in the presence of flammable methane gas and/or coal dust. One phase of the study is an experimental evaluation of methane-air ignition by laser heated small particles. Minimum observed igniting powers for laser energy delivered by 200-, 400-, and 800-um core diameter fiber optic cables and directed onto selected targets in methane-air atmospheres were 0.6, L l, and 2.2 W, respectively. Comparisons are made with other ignition phenomena, including heated wires.

By D. A. Reynolds

Yields of ammonium sulfate obtained in the carbonization of coal frequently vary from plant to plant, because ammonia is an unstable compound at high temperatures and therefore sensitive, to changes in carbonizing conditions. Differences in byproduct yields of ammonium sulfate obtained at different plants generally are accounted for by variations in plant procedure, either in preparing the coal or in its carbonization. However, technicians of one large corporation,- which frequently obtained higher yields of ammonium sulfate in its Alabama plants than ever were attained in its Ohio plants, "could not reconcile the differences in yields with their plant operations. These investigators suspected that the Alabama, coal used in their southern plant yielded more ammonia because its composition differed inherently from that of the Pennsylvania and West Virginia coals fused in their Ohio plants, although this concept could not be proved readily in their large-scale operations. Their view is supported by experimental data obtained A Beau of Mines-American Gas Association (BM-AGA) carbonization tests) -21 of a large number of coals including those carbonized commercially in Alabama and Ohio.

Jan 1, 1949

By Joseph Gersic

In 1989-90, the Bureau of Mines appraised selected high resource potential areas containing gold, rare-earth-element, or pegmatite deposits in or near the Black Hills National Forest. Available mineral resource data were used to construct mine and mill models and to compute discounted cash-flow rate-of-return analyses. Using this information, the economic feasibility of possible operations and probability (in the nonmathematical sense) of exploration and development within the next decade were assessed. High exploration and development probabilities are forecast for gold deposits around existing and permitted mine areas near Lead-Deadwood and west of Galena. The area east of Galena has low to moderate exploration and development probability; the Rochford area has low to high exploration probability and low to moderate development probability; the Keystone area has low to moderate exploration probability and low development probability; the Medicine Mountain area has moderate to high exploration and low to moderate development probabilities. Exploration probability in the Bear Lodge Mountains area is high for rare-earth elements and gold; development probability is low. Exploration probability for gold in the Mineral Hill area is low to moderate; development probability is low. The current level of activity associated with pegmatite mining in the Black Hills would probably not change significantly in the next decade; both exploration and development probabilities are low to moderate.

Jan 1, 1990

By C. H. Fisher

Sulphuric acid of various concentrations has long been used as a reagent in the determination of olefins and aromatics in hydrocarbon oils4 such as gasoline, kerosene, and neutral oils from coal-tar distillates. Despite its long use, however, there is no general agreement as to optimum conditions and concentration of acid, and numerous methods and modifications have been recommended. In most cases, treatment of the neutral oil with 80 to 90 percent sulphuric acid, followed by distillation to the original endpoint to remove olefin polymers, is recommended for the estimation of unsaturated hydrocarbons. The distillate thus obtained is taken as olefin-free oil and used in later stages of the anlysis. Aromatic hydrocarbons generally are determined in the olefin-free oil by suphonation with more concentrated acid (96 to 100 percent and fuming sulphuric acid are recommended), the hydrocarbons not attacked and removed as water-soluble sulphoric acids being considered as saturated hydrocarbons. In some cases the saturates are examined further by differentiating between cyclic (naphthenes) and acyclic hydrocarbons (paraffins), Generally this is achieved by physical methods, although strong sulphuric acid is known to react preferentially with some types of saturated hydrocarbons. It was the purpose of the present work to make a general study of this type of analysis and to investigate the reactions of hydrocarbons under conditions often used in analyses that employ sulphuric acid reagents. Since previous work is not in good agreement, the optimum concentrations of acid for the different stages of the analysis were determined. Several sulphuric acid methods previously recommended and new modifications were compared, two synthetic solutions being used as the reference oil. The results obtained are presented below under separate headings.

Jan 1, 1937

By William J. Campbell

This Bureau of Mines report describes a study conducted to determine the relationship of mineral habit to particle size and shape characteristics for prismatic, acicular, fibrous, and asbestiform varieties of tremolite. Particle measurements were made with the petrographic microscope at X 1,250 and the scanning electron microscope at magnifications up to X 10,000. All of the varieties of tremolite, upon Wiley milling, produced a significant percentage of particles that meet the Federal regulatory criteria for counting as asbestos fibers. However, only the asbestiform variety gave milled particles that fell into a size range of >10 µm in length and <0.5 µm in width; some medical scientists consider this range significant for production of adverse health effects.

Jan 1, 1979

By C. H. Fisher

Sulphuric acid of various concentrations has long been used as a reagent in the determination of olefins and aromatics in hydrocarbon oils4 such as gasoline, kerosene, and neutral oils from coal-tar distillates. Despite its long use, however, there is no general agreement as to optimum conditions and concentration of acid, and numerous methods and modifications have been recommended. In most cases, treatment of the neutral oil with 80 to 90 percent sulphuric acid, followed by distillation to the original endpoint to remove olefin polymers, is recommended for the estimation of unsaturated hydrocarbons. The distillate thus obtained is taken as olefin-free oil and used in later stages of the anlysis. Aromatic hydrocarbons generally are determined in the olefin-free oil by suphonation with more concentrated acid (96 to 100 percent and fuming sulphuric acid are recommended), the hydrocarbons not attacked and removed as water-soluble sulphonic acids being considered as saturated hydrocarbons. In some cases the saturates are examined further by differentiating between cyclic (naphthenes) and acyclic hydrocarbons (paraffins), Generally this is achieved by physical methods, although strong sulphuric acid is known to react preferentially with some types of saturated hydrocarbons. It was the purpose of the present work to make a general study of this type of analysis and to investigate the reactions of hydrocarbons under conditions often used in analyses that employ sulphuric acid reagents. Since previous work is not in good agreement, the optimum concentrations of acid for the different stages of the analysis were determined. Several sulphuric acid methods previously recommended and new modifications were compared, two synthetic solutions being used as the reference oil. The results obtained are presented below under separate headings.

Jan 1, 1937

By S. P. Kinney

The efficient operation of a blast furnace is primarily dependent upon efficient contact between the descending stream of solid materials and the ascending stream of gas. The United States Bureau of dines is conducting a program of research dealing with the interior of the present-day furnace. The work is being carried oat by.(1) observations on commercial furnaces end (2) experiments in the laboratory. Through the courtesy of the officials of the Illinois Steel Co. it was possible to make a detailed investigation of the interior of the shaft of Number.4 furnace at the company&apos;s South Works, South Chicago, Ill. The experimental work is to be reported in a U. S. Bureau of Mines bulletin which will include the results of several thousand observations on the interior of the shaft of this furnace. Such of the data as are presented later in this paper constitute only a brief summary.

Jan 1, 1929

By L. H. Adami

This paper reports the results of solution calorimetry conducted to obtain the heats of formation of crystalline FeS04?6.952H20 and FeS04?1.008H20, from. which values were derived for the stoichiometric compounds FeS04?H20 and FeS04?H20. Also included are derived values of the free energies of formation and dehydration. This work was undertaken primarily to fill a need for data for pure, easily obtainable ferrous compounds that are suitable for use as calorimetric intermediates, The ferrous sulfate hydrates meet the essential requirements for this use.

Jan 1, 1963

By J. E. Conley

Available statistics show that the demands of the American chemical industry for sodium sulphate have been increasing slightly in recent years. The supply from domestic sources, particularly In the form of byproduct salt cake from the acid manufacturers, has been tending to decrease due to the growing manufacture of synthetic acid. Both hydrochloric and nitric acids are being synthesized from their elements. The natural result has been that a smaller amount of salt cake is available. Simultaneously, the expansion of the Kraft paper industry, especially in the South, has brought about greater demand for sodium sulphate in that section. This dean is being met by domestic byproduct salt cake, by imported German sodium sulphate made from potash waste liquors, and by favorable situated domestic deposits of Glauber salts and tile anhydrous salt, thenardite. No shortage of natural sodium sulphate exists in the United States, but usually such deposits occur in semiarid regions far removed from transportation facilities and from markets. Moreover, the major portion of the natural deposits is Glauber salt or mirabilite (Na2SO4 ? 10H20), which must be dried or dehydrated in order to meet consumer requirements. The water of hydration represents, roughly, 55 percent of tae total weight of the crude salts and therefore has a very important influence on transportation costs. In marry instances the cost of getting, even the dehydrated product to market is the deciding economic factor. Therefore, the recovery oil production of anhydrous sodium sulphate from plant-.waste liquors or from natural brines of suitable composition might be economically feasible. The U.S. Bureau of Mines, at its nonmetallic Minerals Experiment Station, New Brunswick, N. J., has, for a number of rears, been investigating the commercial possibilities of treating the complex saline mineral polyhalite (K2SO4?NgSO4?2CaSO4?2H20) for the recovery of potash and magnesia. Certain proposed processes (1, 2, 3, 4)4/ yield waste liquors that contain the bulk of the magnesium and sulphate originally combined as magnesium sulphate in the polyhalite molecule. Sodium chloride In limited concentrations is also present, as extensive beds of salt occur in strata overlying the polyhalite deposits. A typical waste liquor would contain:

Jan 1, 1936

By P. M. Gruzensky

In view of some of the outstanding properties of chromium, considerable effort has been made in recent years to prepare the high-purity metal in ductile form. The object of this investigation was to obtain such metal by electrolysis of chromic acid solutions and to determine the conditions that yield optimum results. The apparatus is described, as well as the parameters that received consideration. Ion-exchange resins were employed to remove cation impurities from the electrolyte. Tensile specimens prepared from the electrodeposits by arc melting, press forging, swaging, and drawing, were ductile at room temperature. INTRODUCTION Metallic chromium displays an exceptionally high resistance to corrosion, oxidation, and wear at elevated temperatures. Although these properties are utilized to some extent when chromium is alloyed with other metals, such as in stainless steels, high-chromium alloys and pure chromium are not employed as engineering materials because of a serious lack of ductility and impact resistance at room temperature. Because high-chromium alloys appear promising as refractory metals for applications such as in gas turbines, much interest has been shown recently in the preparation of uniformly ductile chromium and in determining which factors contribute to its brittleness.

Jan 1, 1957

By S. H. Ash

The paramount responsibility of Government is to protect the general welfare. One of the chief functions of the Bureau of Mines is to investigate and publicize methods of increasing safety and efficiency in mining operations. In an industrial civilization, energy resources constitute the foundation of a sound economic structure (14).4/ Coal is only one source of energy, but it provides more than half the energy consumed in the United States.

Jan 1, 1946

By L. C. IlsLey

In the normal operation of mines, the aggregate effect of many seemingly minor op rations may be very important as respects economy and safety. Anion: these operations is the method employed in coupling and uncoupling mine cars. For economic reasons the equipment in mines has not been protected as well as railroad equipment. It is pertinent that haulage accidents rank second in severity among mine accidents, and that manual coupling of cars has been one of the most frequent causes of such accidents. One study4/ revealed that coupling was responsible for about 20 percent of haulage accidents underground. A review of early conditions on steam railroads, which were responsible for the introduction of safer methods of coupling cars, indicates how conditions in might be improved. THE STORY OF RAILROAD COUPLING As any considerable improvement in mine-car coupling probably will follow lines somewhat similar to those that brought order out of chaos for the railroads, it seems appropriate to review briefly the steps taken to improve railroad coupling from the days of link and pin couplings of various types to the adoption of the standard ?M.C.E? automatic coupler.

Jan 1, 1943

By W. D. Ludemann, E. A. Loria, E. A. Rowe

The isothermal recrystallization of electrorefined vanadium has been studied as a function of annealing time , temperature , and prior deformation . Specimens were cold- rolled from 30- to 75 - percent reduction in thickness , then annealed from 700 ° to 1,200 ° C at time periods ranging from 1 minute to 96 hours . The course of recrystallization was followed by means of hardness , metallographic , and X- ray techniques , and a recrystallization diagram was constructed . Interpretation of the data indicated that there was around 50- percent softening due to recovery ( first stage of softening) before recrystallization began . The defining of recrystallization limits with respect to the amount of deformation was precisely established for electrorefined vanadium . More than 30- percent reduction was necessary for recrystallization to occur at 850 ° C. With 60- percent reduction , it was initiated at 750 ° C and completed at 950° C. The activation energy for recrystallization , as derived from the data , was 95,300 cal per mole for 60 - percent reduction and annealing at 750 ° to 900 ° C. Recrystallization by the mechanism of nucleation and growth was the principal process during the second stage of softening . minor part of the second stage of softening took place as strain- induced boundary migration , which was observed in specimens reduced 30 percent , bent in L- shape , and annealed at 950 ° C. Grain size decreased significantly only with the largest reductions and annealing between 750 ° and 950 ° C. Grain growth was expressed by the empirical relation D = KKtt"" ,, the exponent being the same at 60- percent reduction and annealing from 750 ° to 900 ° C. Accordingly , the activation energy for grain growth was 75,000 cal per mole .

Jan 1, 1964

By R. L. Grayson, W. E. Wallace, T. Simonyi, J. C. Harrison

"Application of an SEM-based methodology suggests a reason for past contradictory results on the relationship between quartz and coal workers' pneumoconiosis (CWP). Results indicate that coal seams with the same bulk analysis of quartz may have different amounts of surface-availablequartz. Our research shows that the amounts of pure and surface-available quartz in a respirable dust vary directly with the rank of a coal seam, except in the case where rock materials are mined. The estimated amount of surface-available quartz therefore provides a measure of the quartz-related fibrogenic potential of a respirable dust.INTRODUCTIONFrom our previous work (Grayson, 1991), we have shown that the amount of pure quartz in a respirable coal mine dust sample appears to vary directly with the rank of the seam (using fixed carbon as the basis for comparison), except when a substantial rock parting, roof or floor are mined. Our other work (Wallace et al., 1989) showed that high-silica particles in a clay mine may generally be coated with clay, rendering the quartz core non-available for surface reaction in the lung. The combination of these findings led us to hypothesize that the coating phenomenon may indeed be present in coal mines as well, and that a rank relationship may be present regarding this phenomenon. Thus higher rank coal seams may have more surface-available quartz as well as more pure quartz particles in their respirable dusts. The scientific protocol for testing this hypothesis and the results obtained to date are discussed in this paper. Thus far, there is no reason to doubt that the relationship holds."

Mar 1, 1992