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By L. J. Kane

While analyzing synthesis gas produced from coal, the Bureau of Mines found that conventional procedures for naphthalene determination were difficult and time consuming. The Bureau developed a rapid and sensitive turbidimetric procedure, which requires only simple instruments and hence can be used in plant-control laboratories. The gas is passed through a saturated aqueous solution of picric acid at 3° to 4° C. whose turbidity is then measured at room temperature. A dispersing agent is added to prevent coagulation of the suspension on warming. Only about 1 mg. (0.015 grain) of naphthalene need be absorbed, and precision and sensitivity are a few ten-thousandths of a grain, or a few hundredths of a grain per 100 cubic feet. The determination can be completed less than 10 minutes after absorption. INTRODUCTION One of the functions of the Branch of Coal Gasification, Bureau of Mines, Morgantown, W. Va., is to develop economical methods for manufacturing, from coal, a mixture of hydrogen and carbon monoxide for producing hydrogen, methane, and other gaseous fuels. This raw gas may contain many impurities, including naphthalene. This impurity is usually determined by first forming naphthalene picrate in a water solution of picric acid, separating the picrate, and titrating the unreacted picric acid or the picrate itself.

Jan 1, 1957

By R. J. Fantel

To determine the availability of phosphate rock from domestic re- sources, the Bureau of Mines evaluated the potential production of phosphate rock from the demonstrated resources of 130 mines and deposits. The evaluation included an estimation of resources, engineering methods, and capital and operating costs, and an economic analysis to determine each operation's average total cost of production over the life of the mine, including a 15-pct discounted-cash-flow rate of return on all investments. Quantified but not evaluated in this report are substantial phosphate resources at the inferred and hypothetical resource levels. The 130 mines and deposits contain 6.4 billion tons of recoverable phosphate rock product, about 20 pct from producing mines. At total production costs of under $30 per ton in January 1981 dollars, about 1.3 billion tons of phosphate rock product is potentially available, over 90 pct from producing mines. This study suggests that production from low- cost, high-grade phosphate mines now in operation will decline during the next decade, and new higher cost, Lower grade mines will have to be developed to satisfy demand into the next century, In addition to the demonstrated resources evaluated in this study, 7 billion tons of inferred-level and 24 billion tans of hypothetical- level phosphate rock are potentially recoverable, which, in part, includes material containing high amounts of magnesium, Much of this material could likely become available in the near future.

Jan 1, 1983

By R. L. Grayson

"Compliance standards for respirable dust, which are reduced because of high quart: concentrations, have become an industry-wide problem. Research on the physical and chemical character of quart-classified particles in respirable coal mine dusts indicates that they may exist in intermixed layers or may be coated by clay or coal material. The relative amount of intermixing varies with the coal seam being mined. If most of the quart: particles of a mine dust are ""pure,"" then the dust may have a high fibrogenic risk potential because of truly free silica and the compliance standard should be lowered. lf, however, quart: is locked inside another material matrix, or coated, a reduced compliance standard may not be appropriate.Although much research has been done on coal workers' pneumoconiosis (CWP) over the past decades, the etiologic agents of the disease still have not been pinpointed. The predominant methods of characterizing respirable coal mine dusts were bulk analysis techniques for determination of elemental and mineralogical concentrations, the results of which were used in statistical analyses to determine relationships between dust composition and the occurrence of CWP. These methods are incapable of finding the etiologic agents in the dust primarily because of complicated and confounding physiochemical factors, which may be discovered if the focus of characterization was done on a dust particle level.The SEM/EDXA-based research discussed here shows a significant difference in the number of ""pure"" quartz particles in respirable dusts collected from different mines. Some of the results have been reported previously (Grayson, Andre, and Simonyi, 1988). Concurrent research by other investigators (Wallace et al., 1989) demonstrates an SEM/EDXA-based methodology to pinpoint the location of the ""contaminating"" substance(s ) in a quartz-classified particle. The research of the European Economic Community has also begun analyses on the respirable-dust-particle level (Robock and Bauer, 1988).Since the compensatory and intangible costs of CWP are substantial in the United States, it is important that the etiologic agents be determined and then either controlled or neutralized in a cost-effective way. This line of research is especially important consid-ering the forecasted. near-term growth of coal production and the evolution of high productivity longwall panels (an immediate problem in compliance) and continuous mining sections ( a probable future problem).This need has been accentuated now that nearly all respirable dust samples submitted to MSHA are analyzed for free silica (Tomb, Parobeck, and Gem, 1986). Today a real problem exists in the coal industry, both underground and surface, because of high quartz levels in respirable dusts causing substantially reduced compliance standards (Murphy, 1989).The combined results of the respirable dust particle investigators indicate that conventional bulk sample analyses may not faithfully represent the amount of biologically available or active quartz in all mines with a high level (greater than 5% ) of quartz in the dust For example, some mine dusts might contain predominantly occluded (or coated) quartz particles where bulk analysis would result in anomalously high ""free silica"" measurements. The same result would occur when quartz particles are intermixed substantially with other minerals that can alter the surface of the composite particle away from a quartz-behaving character."

Mar 1, 1992

By H. M. Smith

Data from the Bureau of Mines routine method for the analysis of crude petroleum are used to characterize crude oils. Some data are used directly while other data are used to calculate the aromatic) naphthene) and paraffin contents of the distillation fractions and the correlation index of the paraffin-naphthene portion of the fractions. The calculated properties show significant differences in composition between crude oils. The methods of calculation and interpretation of data are explained and illustrated.

Jan 1, 1966

By C. M. Romanowitz

This report deals with the factors which should be considered in evaluating a placer deposit and selecting a dredging system for mineral recovery. Overall dredging feasibility and the design of dredging systems are reviewed. Excavation methods, each with its advantages and disadvantages, are compared. Direct operating costs, both original and updated, of gold dredges with bucket capacities of 6 to 18 cubic feet are included. Costs vary with digging depth, changes in environmental conditions, and physical characteristics of the placer, all of which affect excavation rate and recovery. The costs, updated with appropriate indexes, should be used only as guidelines to evaluate potential dredging projects with similar characteristics. The relation of direct dredging costs to annual production is graphically illustrated by a family of curved envelopes that span dredge sizes from 2-112 to 18 cubic feet. A curve fitted to the data expresses the relation of direct costs to annual production for 151 dredge-years.

Jan 1, 1970

By A. U. Miller

Protection against fire is a greater problem at a coal mine, than at an ordinary industrial plant. Generally mines are located in isolated districts and do not have the protection of city fire departments; consequently fire fighting aquipment must be installed by the mining company. Fire protection around a mine is just as essential as it is in the city.. and undoubtedly is more important if the fire should be underground where many lives would be endangered and all means of escape cut off. A surface fire can generally be attacked from any angle, but an underground fire can be attacked only as conditions will permit.. U. S. Bureau of Mines engineers have investigated many serious mine fires that undoubtedly could have been extinguished in incipiency if a fire extinguisher or fire hose and water had been readily available. In past years very little attention was given..to fire fighting equipment and organization around mines, but in recent years three gen a derde hange of opinion among many of those engaged in mining, and nearly all up-to-date mining companies now have some kind of fire protection about their mine Probably the first company in Illinois to install regular fire fighting equipment and effect a fire fighting organization at its mines, was the Madison Coal Corporation, which operates several mines in Illinois. The main office of this company is in Chicago and the general field office is at Glen Carbon, Ill.

Jul 1, 1930

By J. W. Griflith, P. A. Mack, C. M. Lang, S. Riling

"N-acetyl-beta(B)-D-glucosaminidase is a N-acetyl-beta((B)-D-glucosaminidase enzyme se¬creted by alveolar macrophages in response to phagocytosis of particulate material. Alveolar macrophages participate in the degradation and fibrosis of pulmonary tissue that results in pneumoconiosis. Known quantities of four characterized respirable dusts were bronchoscopically placed into the right caudal lung lobe of macaque monkeys. Bronchoalveolar lavage (BAL) samples were collected from dust-exposed right lung and unexposed left lung of the same individuals at 2-week intervals for 12 weeks after dust instillation. The samples were tested for N-acetyl-B-D-glucosaminidase activity to determine if the enzyme levels could serve as an indicator of pulmonary injury induced by generic coal dusts when compared to known fibrogenic and nuisance dusts. Installation of generic quartz, anthracite, or TiO2 dusts produced significant elevations of enzyme activity and increased numbers of macrophages in the dust-exposed lobes. Elevations in enzymatic activity and macrophage numbers were greatest in response to generic quartz dust. These results suggest that quantitative levels of N-acetyl-B-D-glucosaminidase activity may be a useful indicator of acute and chronic lung injury following exposure to fibrogenic and nonfibrogenic dusts.IntroductionCoal workers pneumoconiosis (CWP) is an occupational pulmonary disease associated with the inhalation of coal mine dust. An important external factor in the development of CWP is the composition of the respirable coal mine dust. A cause-and-effect relationship exists between coal mine dust and CWP, but it has not been shown that exposure to generic coal dusts will cause CWP [12]. Numerous immunological, biochemical, and cellular changes occur in CWP; however, in this study, only N-acetyl-beta(B)-D-glucosaminidase (NAGase), protein, and alveolar macrophages (AM) will be examined [7, 32, 33]."

Dec 1, 1996

By Ann C. Kim

This Bureau of Mines report summarizes the methods and results of many of the laboratory studies on spontaneous heating of coal published in the last 50 years. It includes a brief description of experimental methods, indices of combustibility, and important contributing factors. Adiabatic calorimetry, isothermal calorimetry, [0], sorption systems, or temperature differential are the most frequently used experimental methods. Indices of combustibility include various heating rates, crossing point temperature, ignition temperature, and CO index. Factors that affect the spontaneous heating of coal include air flow rate, changes in moisture content, particle size, rank, temperature, pyrite content, geological factors, and mining practice. Experimental conditions and results from 20 papers are summarized in an appendix, and the bibliography contains 45 references.

Jan 1, 1977

By K. E. Soroka

More than 500 fires are now burning in abandoned coal waste banks and coal deposits in the United States. Once established, such fires can burn for decades, and extinguishing them by conventional methods such as surface sealing to exclude air, excavation to remove fuel, or flushing to cool the fire zone is usually difficult and always expensive. Burnout Control, a technique developed by the Bureau of Mines for the control of abandoned coal fires, involves the accelerated combustion of coal in place with total management of the heat and fumes produced. A burning waste bank or mine is placed under negative pressure relative to the atmosphere, and heat and combustion products are drawn from the combustion zone through an exhaust ventilation system. Heat produced appears as sensible heat in the exhaust, at temperatures as high as 1,0000 C (1,832° F), and could be recovered for the production of steam, hot water, process heat, or electricity. The Bureau's first held field demonstration of Burnout Control was at Calamity Hollow in Allegheny County, PA (near Pittsburgh). Calamity Hollow was the site of an underground mine in the 1900's and was surface mined in the 1940's. In the winter of 1961-62, a fire of undetermined origin was discovered in the exposed coal. In 1963, the Bureau constructed a trench barrier around the fire and a surface seal over the affected area. The fire was isolated but not completely extinguished. In 1979, when the Bureau began work on the Calamity Hollow Mine Fire Project to demonstrate controlled burnout, the fire was still smoldering on the hot side of the trench barrier. The project, which was begun in December 1979 and ended in July 1982, consisted of the design, construction, operation, and subsequent dismantling of a Burnout Control ventilation system. This report is the fifth in a five-part series that describes the Calamity Hollow Mine Fire Project. The first report, part 1, describes the design and construction of the field installation. Part 2 will present the results of a continuous 4-month burnout operation. (Because part 2 involves the analysis of a substantial body of data, it will not be published until after publication of parts 1, 3, 4, and 5.) Part 3 describes the instrumentation used to control and monitor the progress of the burnout operation. Parts 4 and 5 deal with the closeout phase of the field demonstration. Part 4 describes the procedure used to quench the fire, and this part (part 5) describes the final excavation and backfilling of the heated zones. The reports in this series document the Calamity Hollow controlled burnout demonstration which showed that (1) controlled in situ combustion is a feasible method for controlling underground fires in abandoned mines, (2) the resultant thermal exhaust output is sufficient for energy utilization, and (3) water injection-fume exhaustion is a potentially effective method for cooling large underground fire zones. Further investigations of both Burnout Control and the water-injection-fume exhaustion quenching procedure are planned.

Jan 1, 1986

By Stephen C. Tadolini

The U.S. Bureau of Mines conducted a laboratory investigation designed to evaluate the stress and deformation characteristics of fully grouted roof bolts subjected to various magnitudes of end loadings. The experiment and subsequent analysis were completed, utilizing axial deformation data obtained -ultrasonically from forty-one 4-ft, grade 40 roof bolts, with a total of 132 measurement locations along the lengths of the bolts. The ultrasonic measurement instrumentation used in this investigation allowed for elongation measurements without requiring extensive bolt modifications. The results indicate that approximately 39 pct o{ the applied end load dissipated within the first 3.4 in of the bolts. However, only 3 pct of the applied load was realized beyond 28 in of the grout column. Data are presented individually for every 6-in increment of bolt length, and analysis was performed using statistical, nonlinear equations developed for 5,000 and 8,000 lb loading conditions.

Jan 1, 1990

By N. N. Moelbs

The U.S. Bureau of Mines is conducting research on many topics relating to the hazards of coal mining, increased production, and protection of the environment. One area of research that has received scant attention in recent years is that of water inflows, probably because few fatalities in the United States have been attributed to them. As mining goes deeper, the problem of water in 1ow could increase dramatically because of adjacent or overlying mines in which huge water pools are impounded. Inaccurate mine maps and ineffective barriers can constitute a serious problem for operators both from gradual inflows and sudden inrushes of water. This report describes a wide but ineffective barrier that permitted an average 240-gpm inflow to a developing mine from an adjacent mine. The anomalous geologic structure that facilitated this leakage is described, demonstrating that size, alone, is no assurance against serious leakage. Some recommendations for managing serious water inflow are included.

Jan 1, 1989

By A. R. Taylor

This report describes the design, construction, and operation of a low temperature adiabatic calorimeter for measuring heat capacities of solids or liquids from 60° to 300° K. A brief discussion of the basic theory involved in chemical thermodynamics and the problems involved in obtaining accurate experimental data is presented. The operation of the calorimeter was tested by measuring the heat capacity of a sample of benzoic acid obtained from the National Bureau of Standards over a temperature range of 60° to 300° K. The measured heat capacity values of the benzoic acid compared favorably with similar values obtained by the Bureau of Standards, the maximum deviation being 0.5 percent. THEORY A brief discussion of the basic theory involved in chemical thermodynamics will illustrate the applications of heat capacity data and the problems involved in obtaining accurate experimental data.

Jan 1, 1962

By R. A. Beall

Homogeneous zirconium-alloy ingots have been cast on a production basis by the consumable-electrode arc-melting process at the Northwest Electrodevelopment Experiment Station, Bureau of Mines, Albany, Oreg. This paper describes the various methods used to introduce alloying materials into the ingot and evaluates 1 each method by the degree of homogeneity of resulting ingots, as determined in tests on sections cut from the ingots. As many as 30 or more ingots, each 6 to 10 inches in diameter and weighing 300 to 500 pounds, were melted, using each method; and, as most of them subsequently were fabricated to strip 0.1 inch thick, the test results are considered to be representative of production practice. Ingot homogeneity has been considered more difficult to achieve in arc-melting practice than by methods where the molten metal is poured into molds and the addition can be stirred into the total mass of metal before casting. Owing to the unique requirements of consumable-electrode arc melting the addition can be made only to that part of the total mass of the ingot that is molten at one time. Observation of the flowlines in 500-pound ingots produced at Albany indicates that the molten pool has a maximum depth about equal to the ingot diameter. The weight of metal molten at one time is, therefore, not over 100 pounds. Characteristically, the arc-melting process is conducive to segregation, which can be overcome, at least partly, by adding the alloy constituents almost continuously during casting.

Jan 1, 1956

By Willard L. Hunter

The Bureau of Mines studied the effect of temperature upon the reduction of chromite by carbon and the relative reducibility of chromites as a function of their composition. Ferric oxide was also studied to provide comparative data. Pellets weighing approximately 1 gram and containing 70 percent ferric oxide, chromic oxide, or chromite and 30 percent graphite were subjected to closely controlled temperatures under a flow of argon for 15 minutes. The amount of CO and CO2 evolved was measured, and the reduced sample was analyzed by X-ray diffraction techniques. The reduction of Fe2O3 was studied over a temperature range of 600° to 1,400° C, while the reduction of Cr2O5 and chromite was conducted from 9000 to 1,621° C. The temperature above which appreciable reduction of Cr203 by graphite took place was 1,125° C. The temperature at which significant reduction started for three of the four chromite samples was approximately the same, indicating that there was concurrent reduction of iron and chromium oxides in the chromite mineral rather than selective reduction of iron oxides followed by reduction of chromic oxide. Rhodesian chromite appeared to dissociate at a lower temperature with concurrent reduction of iron. Based on the temperature at Which chromite was 50 percent reduced in 15 minutes, Transvaal chromite reduced most easily, followed by Mouat, then by Kampersian, and finally by Rhodesian DFC material. Statistical analysis of test results indicated that the ferric iron content of chromites affects their reduction behavior more than any other constituent.

Jan 1, 1966

By William M. Knuth

The objectives of this study were the evaluation of the technical and economical feasibility of utilizing color and color infrared aerial photography to satisfy some informational needs for pre-mine planning, mine progress monitoring, and reclamation monitoring. Seven aerial data collection missions were conducted within a two year period over strip mine sites in Pennsylvania. Scales of 1:6,000; 1:12,000; 1:24,000; and 1:48,000 were flown on the first aerial mission. The 1:12,000 was chosen as the optimal scale for the remaining six flights. An extensive literature and legislative review and discussions with strip mine operators identified the informational parameters that could possibly be obtained from aerial photography. Interpretability accuracies were evaluated for parameters in the broad categories of land use, soils, water, vegetation, and geology. Seasonal interpretation characteristics were noted for infrared photography. Man hours for photointerpretation and costs of aerial data collection were monitored closely and incorporated into a cost benefit analysis. Those parameters that could be mapped, identified, or measured with accuracies =75 percent were incorporated into a photointerpretation training manual. An additional analysis was performed to determine the applicability of the interpretation methodologies and results developed for Eastern sites to Western surface coal mining sites. In addition, a separate aerial photographic interpretation manual was produced during this contract. It is intended to be utilized by eastern and midwestern surface mine operators and regulatory personnel.

Jan 1, 1978

By H. C. Ko

The Bureau of Mines maintains an active program in thermochemistry to provide thermodynamic data for the advancement of mineral science and technology. As part of this effort, the standard enthalpy of formation at 298.15 K, ?Hf°, for 2CdO-CdSO4 was determined by HCI acid solution calorimetry to be -345.69 ±0.61 kcal/mol.

Jan 1, 1983

By Richard F. Link

The principal procedures for the statistical analysis of gold assay and other trace-element data depend on applying either the normal frequency distribution or the lognormal frequency distribution. The consequences of applying both methods are examined through reference to example data from United States and South African gold mines. It is concluded that for estimation of average grades, except for certain data with a very high coefficient of variation (ratio of standard deviation to mean), use of the lognormal distribution is ordinarily undesirable because bias may be introduced and little efficiency can be gained. However, if biased average grades can be tolerated, as in the examination of data from surveys in exploration geochemistry, use of the log-normal distribution may be desirable. Various statistical analyses are detailed, and the tables presented to implement the analyses are more complete than those previously published.

Jan 1, 1971

By E. R. Palowitch

This report stems from a study by the Bureau of Mines of the possibility of reducing coal filter-cake moisture by applying radiant heat directly to the filter cake while under vacuum during the drying phase of the filter cycle. One disk of a 4-foot-diameter vacuum filter was equipped with gas-fired radiant-heat generators and the effect of radiant heating on the moisture content of a variety of filter cakes was studied. The results of this investigation show that this process can best be described as a filter aid capable of increasing the effectiveness of conventional filtration approximately 6 percentage points of moisture. The operating cost of removing water by this method is somewhat lower than the average operating cost of thermal drying and is considerably cheaper when the total cost is considered. Removal of water from coal that has been wet-cleaned is an important part of the overall coal preparation process. Water is a contaminant, and it is foolish to wash coal to reduce its ash content and add inert water in the process. In some instances the removal of water is actually more important than the removal of ash-forming minerals; its weight adds to the cost of transportation, and its evaporation during burning or carbonizing absorbs useful heat. Fine coal that contains more than about 10 percent moisture is notoriously difficult to handle. A problem thus exists for which there are sound practical and economic reasons to seek a solution.

Jan 1, 1961

By L. C. IlsLey, R. A. Kearns

"The electrical section of the Bureau of Mines has obtained copies of all available State safety rules and regulations in order to make a study of those portions of the codes relating to electrical equipment. While it has been found almost impossible to compare the several codes as a whole, comparison of those regulations dealing with a single subject has proved both interesting and instructive.Sixteen states have rules or enactments having reference to telephones and the present paper covers a compilation of these references. It is believed that data of this kind will be of service to commissions or other bodies contemplating the revision of existing codes.The compilation taken from the various codes follows: State Rules and Regulations.California.Sec. 5 (Par. c) Telephone communication shall be maintained between a co-operative station and each mine which it supplies. If the foreman in charge of a station does not reside thereat, his residence also shall be in telephone communication with each mine supplied by his station.Sec. 8 (Par. a) Whenever a fatal accident occurs in or about any mine, notice thereof shall be given promptly by telephone or telegraph if possible, followed by a notice in writing to the chief inspector, by the superintendent or other person having immediate charge of the work at the time of the accident."

Jun 1, 1921

By J. T. McCartney

The Bureau of Mines has developed an automated reflectance scanning microscope system, primarily for determination of volume proportions, size distribution, and mode of association of the physical (petrographic) components of coals. The process, which is potentially more rapid and objective and less tedious than a visual microscopic procedure, involves magnetic tape recording of several millions of reflectance readings on micro-meter sized areas of polished coal surface and computer analysis and interpretation of some characteristics of the coal components. The system was tested in a study of pyrite distribution in steam coals. The application was essentially successful, but defects in polished pyrite surface characteristics and problems in adequate sampling prevented completely satisfactory results. Pyrite con-tent and coal-pyrite particle association could be determined nearly as well as by visual microscopy, but size distribution data were less acceptable.

Jan 1, 1969