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By W. D. Musgrove, B. W. Gandrud, A. C. Richardson

"INTRODUCTION The Cahaba coal field is the second largest coal—producing area in Alabama. This field underlies parts of Shelby, Jefferson, St. Clair, and Bibb Counties and has an area of about 270 square miles. The Cahaba formations contain a number of coal beds, about 8 of which are mined at present. Although the area contains many folds and faults, samples from various mines and beds indicate that, except for the variation in ash content, the coal from this field is very uniform in character and quality. It is a high-volatile bituminous coal used chiefly for steam-raising purposes and domestic fuel. The coal as mined usually contains too high a percentage of impurities to be marketed without some preparation. The majority of the mines have washing plants in which jigs are the favorite type of equipment, although at some mines tables are used for cleaning the slack sizes. The washing characteristics of the coal from the Cahaba field are very uniform and differ from those of the near-by Warrior field, in that the coarser sizes contain a much lower percentage of bony material than the finer sizes. In general, the bone increases with decrease in size. It breaks into thin flakes, making difficult its elimination in the cleaning process, and gives rise to what is known among the washery operators of the Cahaba field as the ""rash problem.""A previous publication 5 referred to rash from the standpoint of jig operation and suggested some means of handling it with jigs. This report presents the results of table tests on two samples of fine coal from the Thompson and Woodstock beds, respectively, of the Cahaba field to determine the influence of rash on table efficiency.This investigation has been made in connection with the study of coal-washing problems now being conducted by the U.S. Bureau of Mines and the University of Alabama, with the cooperation of the different coal operators of Alabama."

May 1, 1934

By R. P. Adams, R. A. Beall

The Bureau of Mines developed a method to melt and cast specimens of hafnium- carbon alloy and studied their properties . A rotating - ladle vacuum or inert atmosphere arc furnace was designed , special electrodes and molds were developed , and operating procedures were worked out for casting small shapes . The cast specimens were evaluated according to their carbon content for melting point , density , microhardness , electrical resistivity , and oxidation resistance . Lattice dimensions were determined , and metallographic specimens were prepared . Photomicrographs were taken of specimens containing 2.72 , 5.50 , 6.47 , 9.97 , 12.8 , and 15.7 weight - percent carbon , and their grain structures were compared .

Jan 1, 1963

By G. E. McElroy

Economic solutions of problems of mine-ventilation improvement can be found by mathematical analyses of alternative methods of procedure, but, in the case of our older bituminous-coal mines, the airway network is usually so complex that mathematical solutions are too tedious to be practical. Recourse usually is made to extremely costly and uncertain trial-and-error procedures with the existing layout and equipment. The resulting errors often prove costly and sometimes create hazardous conditions. Both the economic and safely aspects of alternative methods of ventilation improvement may be rapidly and cheaply investigation with analogue computers. An electrical analogue computer, designed and built especially for analyzing mine-ventilation-distribution problems, has been placed in service by the Bureau of Mines at its Pittsburgh, Pa., Experiment Station. It is a nonlinear, low-voltage, fluid network analyzer of a type developed by Malcolm S. Mcllroy, professor of electrical engineering at Cornell University. It was designed in close coopera¬tion with Professor Mcllroy and built by the Standard Electric Time Co., Springfield, Mass. It is the seventh unit of this type to be placed in service and the first designed for mine airflow problems. The other six were designed for either water- or gas-distribution analyses. Three are much larger and more expensive units. The largest unit has a capacity of 20 sources, 576 mains, and 180 loads, or regulated-flow paths. The Bureau unit has a capacity of 5 sources, 128 mains, and 48 loads.

Jan 1, 1954

Mine fires pose a serious hazard to the health and safety of mine workers. They occur regularly and their effects can be devastating. Objective Provide mine safety personnel, MSHA, and equipment manufacturers with a comprehensive, up-to-date, and well-documented database of metal and nonmetal mine fire incidents in the United States from 1950 to 1984 and perform a statistical analysis of these incidents. The data-base is designed for use by mine engineering and safety personnel to aid in determining especially hazardous practices or conditions.

Jan 1, 1988

By W. W. Graff

This paper describing the mining practice at Mine No. 5 of the Marquette range, Michigan, is one of a series being prepared by the Bureau of Mines on mining practices, methods, tend costs in the various mining districts of the United States. The top-slicing system of mining, has been used ever since the present operating company took control of the property in 1903, the main level and sublevel layout being chanced only as local conditions required and the use of mechanical equipment increased.

Jan 1, 1930

By Irving Hartmann

As part of the continuing effort by the Bureau of Mines to promote mine safety, research work is being conducted at the Experimental coal mine, Bruceton, Pa., on the prevention of coal-mine explosions and on other mine-safety problems. The principal subjects studied during the past 2 years are briefly described in this paper. Although at present these problems are relevant particularly to the mine layout and to high-speed mining practices in numerous American coal mines, it is hoped that the findings will prove interesting and useful also to our European research colleagues. Some of the investigations treated here will be presented in greater detail in forthcoming Bureau of Mines reports. 1. UNDERGROUND STORAGE OF COAL CUTTINGS The seams in mist American bituminous-coal mines are undercut, shear-cut, or top-cut before blasting. The cuttings arc generally loaded out with the balance of the coal. However, in some mines it is not economical to load and remove cuttings from the mine. This applies especially if the cut section of the seam is of appreciably lower grade than the rest of the coal, or if the cut is made partly into an adjacent stratum that is high in incombustible content. In such mines the cuttings are sometimes stored in random heaps in rooms or other areas, along the ribs of mine entries, or in layers on the floor of rooms or entries.

Jan 1, 1956

By Jack I. Paige

The devitrification of lithium silicate glasses was studied to determine the effect of annealing temperature, composition, and additives on nucleation and crystallization. High-purity glasses, prepared from reagent-grade chemicals, had close to optical quality when prepared by a vacuum induction melting method developed during this research, The progress of devitrification was traced by differential thermal analysis and thermal expansion for those lithium metasilicate-silica compositions containing 80 to 90 percent silica. Microscopic studies of glasses partially devitrified at various temperatures and annealing times indicated that the primary initial mode of formation of individual crystals ,vas from densely crystalline zones that filled in as crystallization advanced Of the additives tested, calcium, potassium, and sodium helped promote devitrification with the least cracking or surface deformation. Tin oxide was most effective in reducing volume contrast ion during devitrification, but was not ClS effective in preventing cracking as calcium or potassium additions.

Jan 1, 1965

By Clinton C. Knox

The Townsite mine, consisting of 40 acres in the town of Cardin, Okla., is in the center of a highly productive part of the Picher-Cardin district of the Tri-State zinc and lead field. Previous to the time of the work done by the Bureau of Mines, the property had been partly explored by churn drilling, and an area-of about 8 acres in the southwestern corner had been exploited by underground workings. The Bureau of Mines investigation had as its object the more intensive development of the northern part of the property where previous drilling had indicated a possible ore deposit of commercial grade. Churn drilling by the Bureau began in September 1942 and continued to February 1943. Twenty holes totaling 4,827 feet of bore were completed. Utilizing the information gained from these drill holes, the Weidman Mining Co., lessee of the tract, sank a shaft and proceeded to the exploitation of the indicated ore bodies.

Jan 1, 1949

By H. B. Brunot, Ilsley. L. C., E. J. Gleim

"INTRODUCTION One of the various phases of the work by the U.S. Bureau of Mines, in its endeavors to minimize the hazards that attend coal mining, is the investigation of electrical motor-driven machinery. The object of this investigation is to foster the development of explosion-proof machines for use in gassy mines. This investigation is conducted under the provisions of Schedule 2C, which prescribes the inspection and tests made upon motors, controllers, and other electrical parts to determine their ability to withstand internal explosion without discharge of any flames. The method of conducting these inspections and tests is described in Bureau of Mines Bulletin 305, Inspection and Testing of Mine-Type Electrical Equipment for Permissibility, published in 1929. Formal approval of a machine for use in gassy mines is not granted by the Bureau of Mines until the machine is found to comply with the requirements, including inspection and test. When it is approved it is entitled to classification as a ""permissible"" machine.The high regard in which machines approved by the U.S. Bureau of Mines are held by engineers of other countries is attested by the growing number of shipments of permissible equipment; to other nations, including Australia, Russia, Norway, Japan, and Manchuria."

Aug 1, 1936

A preliminary program dated April 25, 1974, was prepared for Development Engineering, Inc. (DEI) on research and development. for laboratory, field and other engineering studies on the disposal of retorted oil shale. This program was revised and published as a final document dated December 17, 1974. The document included discussions on the peculiarities of retorted shale materials to be investigated and discussions of the various laboratory and field tests which would need to be conducted to define their physical and chemical properties. The proposed research and development program was divided into eight work phases as follows: I Program Development. II Exploratory Laboratory Tests on Old U.S.B.M. Retorted Shale. III Laboratory Tests on Pilot Plant Retorted Shales, IV Laboratory Tests on Retorted Shale from the Semi-Works Plant, Field, Test Plots and Ponds. V Field Compaction Tests. VI Infiltration Pond Tests. VIII Final Report.

Jan 1, 1975

By Phillip N. Yasnowsky

The thrust of this Bureau of Mines report is to relate the size of automobiles to the price of gasoline, and the use of minerals in automobile manufacture to the size of automobiles. Only one of the many plausible scenarios of public reaction to higher gasoline prices, a switch to economy size automobiles, is developed. No account is taken of other potential impacts such as improvements in public transportation or increased occupancy per vehicle. Furthermore, a gasoline price increase is the only incentive to the greater utilization of economy cars that is considered. A gasoline price increase to $0.60 per gallon would reduce the amount of minerals required to produce the automobiles sold in the United States by an estimated 15 percent. Gasoline prices of $0.80 and $1 per gallon would cause declines in mineral requirements for U.S. automobile sales estimated at 26 percent and 35 percent, respectively.

Jan 1, 1974

By J. F. Barkley

As part of the work of serving as Chairman of Subcommittee 3, Health and Industrial Requirements, of the American Society of Mechanical Engineers' Committee on Air-Pollution Controls, the author assembled the following information on accepted maximum permissible concentrations of air pollutants from the standpoints of health, damage to vegetation, damage to property, and requirements of industrial processes. A search in technical literature was made followed by direct inquiry to all State governments as to their regulations. The subcommittee membership - G. D. Clayton, senior sanitary engineer, Public Health Service, United States Department of Health, Education, and Welfare, Detroit, Mich., Dr. L. Greenburg, commissioner; Department of Air Pollution Control, New York, N.Y., Dr. M. Katz, Defence Research Chemical Laboratories, Ottawa, Ontario, Canada, and Dr. H. H. Schrenk, research director, Industrial Hygiene Foundation of America, Inc., Mellon Institute, Pittsburgh, Pa. - reviewed the information and made very helpful comments and corrections.

Jan 1, 1954

By R. B. Porter

Bench-scale tests were performed by the Federal Bureau of Mines on lignite and subbituminous coal at pressures to 1,000 p.s.i.g. (pounds per square inch gage) in atmospheres of hydrogen or nitrogen to obtain information concerning the influence of pressure on carbonization of normally noncaking coals. The distribution of gaseous, liquid, and solid products as a function of processing pressure was determined. Except for special experiments, the carbonization was at 940° F. In a hydrogen atmosphere above 400 p.s.i.g., agglomeration of the solid residue (especially with lignite) became noticeable and increased directly with the processing pressure. Although in some instances the solid particles fused together, the mechanical strength of the agglomerate was always low. On the basis of visual inspection, the coals agglomerated in the following order of decreasing intensity: (1) Steam-dried lignite; (2) lignite; and (3) subbituminous coal. Addition of lignite tar in quantities to 25 percent by weight of charge did not increase agglomeration or change the carbonization characteristics of the coal.

Jan 1, 1961

By Rena I. Geroyan

This U.S. Bureau of Mines report presents an evaluation of the coal mining industry's impact on the economy of Pike County, KY. A software package called IMPLAN was used to perform the analysis. The results of this study show that coal mining was the primary income producing industry in Pike County in 1990, accounting for about 46% of the county's Total Industry Output, and 21% of the total employment.. Coal production in that year amounted to 29.6 M mt (32.6 M st). Two alternate economic scenarios were developed to study the potential effects of changing coal market conditions on the county. Scenario A assumes market changes result in a coal production increase of 4.5 M mt/yr (5.0 M st/yr), and scenario B assumes a decrease of 4.5 M mt/yr (5.0 M st/yr). Scenario A would result in a 15.3% rise in the value of Pike County's Total Industry Output, adding a total of 1,663 jobs (+6.1%) in all sectors in the county. Scenario B would have the opposite effect, decreasing the Total Industry Output and employment by identical amounts. Such knowledge would allow local and regional officials to anticipate the economic and social impacts of shifts in coal production, and plan accordingly to mitigate impending changes.

Jan 1, 1994

By Robert M. Becker

This report (the second in a series of five) presents the mathematical development in extending the theory of sample reliability from a sample consisting of a fixed number of items to a sample consisting of a fixed amount of items. Examples of a fixed amount of items per sample are samples consisting of a fixed weight or a fixed volume of unequal size particles. The probability distribution functions (those here called the compound binomial and compound multinomial functions) are developed from fundamentals. Their distributions are generalized to include some measured characteristic of the items. Infinite population moments are derived from moment-generating functions, while finite population moments are developed from corresponding infinite population moments using the finite probability operator defined in part 1 of this series.

Jan 1, 1964

By G. E. McElroy

[The ventilation of development faces In nines for diluting Gas or dist concentrations and, in hot nines for providing air-motion cooling effect, by fan-pipe units discharging high-velocity steams of air close to the face, is an important phase of mine ventilation. The effectiveness of such units depends largely on the air-flow distribution between the pipe discharge and the face, n subject on which little definite information is available. A study of the air flow from grills into rooms3/ has provided some basic data, but under conditions so different from mine fan-pipe installations in development ends that the data are of doubtful application to mine installations, owing to differences in air-flow conditions.]

Jan 1, 1940

By Charles W. Huggins

DEVELOPMENT of the electron microscope has permitted man to examine many small objects that could not be resolved by the light micro-scope. Diffraction, spherical aberration, and chromatic aberration are the main factors that limit resolution to about two-tenths micron with the light microscope. No matter how perfectly a light microscope is constructed and operated, it cannot possibly resolve points separated by less than two-tenths micron. Rapid development following World War II has produced many electron microscopes capable of 20 A resolution. Fibrous inorganic minerals are well suited for electron microscopic study. Many micrographs of chrysotile have been published, but electron microscopic study of the amphiboles has been somewhat neglected. New techniques in sample preparation have simplified the study of fibrous material. Ultrasonic energy has been very helpful in sample dispersion. This publication contains a representative group of electron micrographs of natural inorganic fibers that have industrial value. These fibers commonly are referred to as the asbestiform minerals. The Bureau hopes that the knowledge gained through electron microscopy and other scientific study of the natural inorganic crystalline fibers eventually will lead to the production of synthetic fibers that will satisfy the requirements of industry.

Jan 1, 1959

By L. Cheng

This report describes a laboratory investigation of the effectiveness of low-pressure steam and a steam-water spray sequence for the collection of airborne respirable (<10 µm) coal dust. Comparison of present results to previous results obtained with water spray alone indicates that the use of steam in a steam-spray sequence increases the collection efficiency by about 14 percent over that obtained by water spray alone. However, the use of steam to collect airborne dust requires cooling the steam-dust mixture in order to achieve condensation of the steam, and steam does not appear to be an attractive approach for collecting airborne dust in underground coal mining operations.

Jan 1, 1974

By R. A. Franks, G. F. Friel, J. C. Edwards, L. Yuan

Two mine-fire experiments were conducted in the National Institute for Occupational Safety and Health&apos;s (NIOSH) Safety Research Coal Mine (SRCM) at the Pittsburgh Research Laboratory (PRL) which demonstrated that smoke from diesel-fuel fires of 500 kW and 660 kW heat-release rates in a return airway can develop, without causing a complete air flow reversal, into a roof layer that can migrate upwind forming a counter flow to the primary airflow in a crosscut. Subsequently, smoke can penetrate into an intake airway and create a hazardous atmosphere in the intake airway upwind from the fire. Visibility conditions less than 13 m were created by the smoke in the intake airway downwind from the crosscut. Modeling of the event with a three-dimensional, time-dependent, computational fluid dynamics (CFD) program correctly represented the smoke movement.

"For a good many years the Bureau of Mines and various state mining experi¬ment stations have endeavored to develop some method of utilizing the immense deposits of lignite in the United States. Work in relent year has indicated that the best method of this is to drive off the moisture and most of the volatile water from the lignite in some form of carbonizing apparatus leaving a residue high in fixed carbon and low in moisture and volatile matter, which by briquetting can be made into a high-grade fuel. The earlier forms of carbonizing equipment tried were complicated, costly to build and keep in repair, and could not be operated intermittently without being seriously damaged. During the year 1922, however the Bureau of Mines devised a very simple carbonizing oven which produces a uniformly well carbonized product. This oven is essentially a vertical shaft with means for supplying raw lignite at the top and discharging the carbonized limited at the lower end. Air in regulated amount is admitted to the shaft at two horizons, and a zone of combustion maintained through which the column of lignite passes. The lignite is thus carbonized by construction of its contained matter and a small proportion of its fixed carbon, leaving most of the fixed carbon in the carbonized product or ""char"". The degree of carbonization can be closely controlled by varying the volume of air supplied to the oven and the rate of travel of the charre down the shaft.The ""lignite char"" produced is a soft material resembling charcoal more than coal or coke, but somewhat harder than charcoal. A typical analysis is shown in the table headed ""Fuels,"" further on in this papers."

Feb 1, 1924