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By W. H. Young

The thickness of the coal seam is one of the more important items influencing the productivity and general overall efficiency of operation of a coal mine. The average thickness of coal seams mined in the United States has changed very little in the past 40 years. The first measurement of thickness of bituminous coal and lignite seams was made for 1920, when the average thickness was 5.3 feet.2 The average thickness for later years was as follows: 1945, 5.4 feet; 1950, 5.3 feet; 1955, 5.2 feet; 1960, 5.3 feet; and 1965, 5.2 feet.3 Table 1 includes data on number and production of bituminous coal and lignite mines classified by 1-foot intervals of seam thickness mined in 1920, 1945, 1950, 1955, 1960, and 1965. Though bituminous coal and lignite are mined today from seams of exceedingly variable thickness--less than 2 feet to more than 50 feet--a large majority of the production, 62 percent in 1965, came from seams 3 to 6 feet thick. This is not surprising since the coal seam of moderate thickness presents the least mining difficulties.

Jan 1, 1967

By Robert W. Smith

[In a certain application it was necessary to compute the incomplete beta function, ß(1/2, p, q), for a certain set of values of p and q. Since the set of p and q values was much more finely spaced than those in any published tables, the authors have decided to make their results available in this report. In connection with this application, the function ß(1/2, p, q) was needed at various points in the p, q plane at intervals of 0.05, 0.05 p = 2q < 10.00. Fletcher, Miller, and Rosenhead3/ state that the only tables available in the desired range are those of Pearson.4/ However, the interval used by Pearson was not small enough for the present application. For this reason, it was decided to calculate the function ß(1/2, p, q) for p = q = 0.05 (0.05) 10.00. This table is published because of the fundamental importance in mathematical analysis of the incomplete beta function.]

Jan 1, 1953

By Robert J. Anderson

"Introductory Statement.In founding any kind of castings, even with the best practice, scrap castings are produced because of rejections for certain defects. Casting los¬ses are a serious source of financial loss in iron and steel foundry practice as well as, in brass and bronze, but they are particularly serious in aluminum foundry work because of the high value of aluminum. The indications are that in many aluminum foundries in the United States, the casting losses are at times high, and in some plants they are entirely too high when compared with average practice. Of course, defective castings have a residual value for remelting, but if much machine work has been done on a casting before it is scraped, the labor costs alone may exceed the value of the metal and even that of the rough casting.In a foundry, the monetary losses incurred through the production of waster castings can be ascertained from calculations based upon adequate scrap-loss reports. Such reports, when properly kept and interpreted are a valuable aid in finding foundry costs, but they are primarily useful in diagnosing the causes for casting losses. Many aluminum foundries in the United States do not keep adequate records of strap losses; as a result the causes for defective castings can not be traced, nor preventative measures adopted. However, some of the large aluminum foundries keep excellent records, and it has been found that these involve little extra expense for clerical work. If a foundry man will study his daily production of defective and waster castings, he will be able to trace the causes or losses and then make such corrections in his plant practice as will effect a considerable reduction in these losses -- as much as 50.0 per tent in some foundries. If all the present casting losses of the United States could be reduced 50.0 per cent, by eliminating only the readily preventable defectives, a saving of several million dollars would accrue. In the aluminum-foundry industry alone, the saving would amount to about $600,000."

Apr 1, 1920

By S. P. Polack

"INTRODUCTION The purpose of this circular is to correlate the information obtained during personal investigations at the sites of four rock tunnels in the process of construction and information obtained from the records and personal views of the constructors of two other tunnels that were not visited during the, excavation phase of construction and to present this information for the benefit of those who contemplate future construction of rock tunnels.Modern mechanized coal mining requires better, safer, properly alined haulageways and beltways; consequently, better understanding of tunneling methods by coal-mining men will be necessary. The possibility of future high-speed haulage systems utilizing rock tunnels in the more solid rock strata above or below the coal beds must not be discounted. In the past, tunnels have been driven for use in draining and unwatering inundated coal mines. At present, the need for such tunnels is very evident in some parts of the coal-mining regions, notably in the Pennsylvania anthracite fields, and studies along these lines are in progress. The average coal-mining man has little time or opportunity to visit tunnels while they are being exca-vated; therefore, it is hoped that this information will assist him in constructing tunnels safely if he is required to do so in the future.The tunnels described herein differ in size, shape, usage, and, in many instances, in their geological aspects. Full-face, heading and bench, and pilot-tunnel, and enlargement methods of excavation were utilized.The roof-support methods show diverse designs and materials of construction to suit each purpose and condition. The superiority of steel roof support over wood is demonstrated beyond doubt and is shown clearly in the photographs included in this circular.The illustrations (photographs taken by the U. S. Bureau of Mines, the U. S. Corps of Engineers, and others) show many of the necessary steps taken during the excavation and the erection of roof support in tunnels under construction."

May 1, 1950

By Charles H. Shapiro

[In July, 1924, the Bureau of Mines, through its Petroleum Experiment Station, undertook a field study of methods used in oil-field shops for dressing and tempering fishtail bits. The purpose of this work was to suggest chances that would be helpful to the bit-dresser in turning out better treated, harder, and tougher bits, and thus cut down the excessive loss of time caused by too frequent changing of bits. It was the intention to eliminate as much as possible the guess work connected with dressing and tempering bits under the method of judging temperature by eye, by developing; practical methods of controlling temperature. If there were some possible means of accurate temperature control, then it would be an easy matter to bring all bits to the proper temperature for maximum hardness rued toughness, thus doing away with the source of most of the trouble experienced in the present method of bit tempering. Shortly after the Bureau of Mines began its study, a chop In the Stroud, Oklahoma, oil field announced method for tempering fishtail bits that Would increase the drilling footage of each bit treated. The method accurately regulates, by the use of a bath of molten salt, the temperature to which a bit is heated before being quenched to produce hardness. There is nothing new in using silt baths for the, heat treatment of steel, but this was the first attempt to introduce it into the oil fields for use in hardening bits, and for this purpose it proved to be admirably adapted. In tempering, by the old system it is not possible to measure the temperature of the heated bit by means of an electrical instrument for that purpose, whereas this is an easy matter with the now method. If heating steel to slightly above the critical point rind quenching suddenly will bring out its best properties, their here is a method of accurately bringing the steel to that point.]

Jan 1, 1925

By Richard D. Miller, Geraldine P. Norrell

This publication contains routine analyses and related source data for 295 natural gas samples from 18 States collected during calendar year 1963 as part of a continuous survey of the United States for occurrences of helium in natural gas. This survey has been conducted by the Bureau of Mines since 1917. The analyses published herein were made by mass spectrometer and a special helium analysis apparatus, which are described in Bureau of Mines Bulletins 4863 and 576.4 Five previous publications have been made to present the results of 5,998 gas analyses made by the Bureau of Mines Helium Activity , prior to 1963. The first three , Bulletin 486,5 Bulletin 576,6 and Bulletin 617,7/ contain analyses and source data on 5,214 gas samples collected from 1917 to January 1 , 1961. The fourth and fifth publications , which are published as Information Circulars , supplement the three Bulletins and contain 784 analyses of samples collected during 1961 and 1962. The present Information Circular is the third annual publication supplementing the three Bulletins .

Jan 1, 1965

By Robert F. Chaken

The National Institute of Occupational Safety and Health (NIOSH) is dedicated to achieving "safety and health at work for all people -- through research and prevention." An important procedure in pursuing this goal is the NIOSH surveillance studies where the number of injuries are monitored according to demographic, employment, and injury characteristics. These numeric data are then used to identify injury risk factors, develop safety programs, and monitor implemented remediation methods. In essence, ongoing surveillance data form the bases for directing the resources of NIOSH in setting of research and prevention priorities, and in evaluating safety procedures. This surveillance techmque, which is based on the Public Health Service approach to identification and control of disease (1, 2, has been used quite successfully in dealing with relatively high number injuries such as hearing loss, musculoskeletal disorder, respiratory disorder, falls, etc. (2). However a problem arises when extending this paradigm to lower frequency traumatic events; particularly those often referred to as disasters (i.e., high impact events like mine explosions, airplane crashes, etc.). One can ask the question - there hasn&apos;t been a coal mine fire fatality in the U.S. for over ten years, to what extent should we be concerned with mine fire safety (resource-wise)? - The National Traumatic Occupational Fatalities (NTOF) system (4J which NIOSH uses to survey occupational fatalities annually, would suggest that underground mine fires would not be a high priority item in occupational safety. Yet, miners&apos; (i.e., the exposed workers) do consider mine fires and explosions to be major safety concerns. I believe that we need to rethink our evaluation of work place disasters, what is worker exposure, and what are the underlying assumptions (both explicit and implicit) as to the impact that economic, societal and degree of hazard factors make on risk evaluation. The answers to all these problems, will require much broader considerations than those in current surveillance safety and health models. This paper discusses some facets of those considerations.

By Clarence Hall, Spencer P. Howell

This bulletin deals with the characteristic features of the principal explosives used in mining and engineering operations, and espe- cially with the tests that show the suitability of different classes of explosives for different kinds of work. The Bureau of Mines pub- lishes the report as one of a series dealing with tests of explosives and methods of reducing the risks involved in the use of explosives in mining operations. The application of explosives to engineering and mining opera- tions has increased rapidly in recent years. According to a pre- liminary report issued by the Bureau of the Census, 469,000,000 pounds of explosives was manufactured in this country during the year 1909, and the greater part of this production was used for industrial purposes. In large engineering projects and in mining operations requiring the use of explosives the selection of a suitable explosive from the many varieties offered for sale is of fundamental importance. Vari- ous considerations are involved in the selection of an explosive of proper class for the blasting to be done. Many explosives suitable for quarry work are unsuitable for use in deep mines or in close workings. In metal mining and in driving tunnels the character of the gases evolved by the explosive on detonation is an important consideration. An explosive for use in gaseous or dusty coal mines must be formulated and compounded so that its flame temperature and the height and duration of its flame are reduced enough to per- mit its being used with comparative safety. In wet workings or in submarine blasting explosives impervious to moisture are requisite. In extremely cold climates explosives that do not require thawing are desirable, provided they are equally good in other respects. An essential requirement of all explosives, especially of those for use in tropical countries, is that they shall remain stable without change in chemical or physical characteristics.

Jan 1, 1913

By George D. Dub, FREDERICK G. MOSES

The Bureau of Mines, in connection with the investigations of war minerals it conducted, examined the graphite deposits of this country, studied the methods of mining and preparation used, and sought to devise more efficient methods for the preparation of do- mestic graphite, and to standardize the quality of the product. The graphite investigations covered three general phases, as follows: 1. An examination of the deposits in Alabama and other States, and a survey of the methods of mining and preparation used. In this connection methods of sampling and analysis were noted and ex- periments made to determine a standard method of sampling and a rapid but accurate method of analysis. 2. Experimental work on the concentration and refining of domes- tic crucible graphite to improve the quality of the product and to lessen waste. 3. Experimental work in crucible manufacture to determine the properties of domestic flake and the maximum proportions that might be used without impairing the quality of the crucibles. This work was accompanied by photomicrographic study of crucible structure. In this bulletin are presented the results obtained in the first two phases of the work outlined above. The bulletin is in two parts. The first part describes the methods of mining and milling used, suggests a standard method of sampling finished graphite, and de- scribes a rapid and convenient method of analysis developed at the Pittsburgh station of the Bureau of Mines, to which had been as- signed the analytical and microscopic work. The second part describes experiments on the concentration and milling of graphite, which were made at the Salt Lake City, Utah, station. As soon as the reports incorporated in this bulletin were ready, mimeograph copies were distributed to those persons most interested in order to make the results immediately available. The experimental work on crucible manufacture, assigned to the Columbus, Ohio, station, yielded results which were made known to the industry. Á report on this work will be published later as a separate bulletin.

Jan 1, 1920

By Dorsey A. Lyon, Robert M. Keeney

This bulletin is one of a series dealing with the application of the electric furnace to the smelting of ores and the manufacture of alloys, and is published by the Bureau of Mines in the endeavor to increase efficiency in metallurgical processes. The bulletin presents, first, a critical discussion of the possibility of smelting copper ores in the electric furnace; second, the results of the experimental work of other investigators on the electric smelting of copper; third, the results of experiments by the authors on the electric smelting of native copper concentrates and sulphide copper ores; and, fourth, a comparison of the electric furnace with the blast furnace and reverberatory furnace for copper smelting. Before considering the electric smelting of copper ores the reader should understand that the electric furnace was not developed as a competitor of the combustion furnace, but for the purpose of doing high-temperature work that can not be done in the combustion furnace, and for the treatment of ores from deposits that are in regions where fuel is scarce and costly but hydroelectric power is comparatively cheap, as in Chile, and in certain parts of Canada, the United States, and Mexico. Furthermore, it is not the object of this report to try to prove that the electric furnace should replace the reverberatory or the blast furnace, as used at present in smelting copper ores, but to show that the electric furnace may be used with advantage in localities where conditions are not favorable to the use of the reverberatory or the blast furnace. For example, otherwise valuable ore deposits may be situated in a district so remote from, or inaccessible by, railway that the cost of get- ting coke for smelting, or of transporting the ore to a smelter, is pro- hibitive. If there is sufficient water power at hand, from which electric power can be developed at a reasonable cost, and this electric power is used for smelting the ore in an electric furnace, with subse- quent bessemerizing, if necessary, the concentrated product may be

Jan 1, 1915

Analyze variably saturated flow in mining and other environmentally sensitive settings through the use of personal computer (PC) based software. The Problem There is an increasing need for mining companies to quantify water contaminants and their migration in the unsaturated zone. New and innovative computer models are therefore necessary to more accurately assess the potential impact of mining activities on groundwater resources and the environment. Applications for unsaturated flow modeling include (1) assessment of the impact of surface or underground extraction mining on flow conditions; (2) assessment of various hydrologic designs for resource recovery, such as in heap leaching or in situ leach mining; (3) assessment of the transport of conservative nonrcactive constituents in response to migration from spoil piles, or acid mine drainage; and (4) assessment of any combination of the above to facilitate expeditious permitting for mining operations. Since the mid 1970&apos;s there has been a proliferation of mathematical models and procedures for solving unsaturated now problems; however, few of these approaches have been integrated into software for public use. Commercially available unsaturated flow software models typically are limited to a single application and have restricted approaches. For example, computer codes that solve the unsaturated flow problem based on an analytic expression arc restricted to a simple geometric shape, homogeneous and isotropic materials, and provide only information regarding pressure and flow conditions in specified wells. The variably saturated computer codes that take advantage of the finite difference or finite element approach arc often restricted to either steady state or transient solutions; utilize one specific moisture-retention relationship and moisture-dependent permeability function; do not account for hysteresis; and are used with specific hardware such as a mainframe or work station. This restricts their use because they arc hard to interface, and arc often poorly documented, support dependent, and expensive. The mining community needs a flexible, more broadly based, variably saturated fluid flow simulator for the PC-platform to more accurately predict fluid movement in the mining environment.

Jan 1, 1991

By H. J. Sloman

"INTRODUCTION Industry, including coal mining, has come to realize that to prevent accidents the human element must be given more consideration than was customary in the past. In formulating safety rules and regulations and in the enactment of laws governing mining, too often enforcement is emphasized rather than the means of gaining willing compliance.' The purpose of this paper is to call attention to the human side of accident prevention, and the approach to this important and much-discussed subject will deviate somewhat from the usual discussions.The human being is a complex mechanism, both physically and mentally. It is difficult to establish a common denominator for the actions of humans, except in general. In establishing mining laws, rules, regulations, and standards, the ultimate objective should be to gain the best possible response of workmen, so that optimum results in accident prevention may be obtained. The complexity of human beings is apparent when the many ways 1n which they differ are considered. Some of these differences are manifested in emotional and phlegmatic types, degrees of intellect or native intelligence; and in hopes, desires, aspirations, and philosophies of life. How much simpler ac¬cident prevention would be if the response to laws, rules, regulations, or standards were equivalent to the definite movements of puppets responding to pulls on strings. Each time, the strings are pulled in exactly the same way, the puppets will respond in exactly the same manner. Human beings, although having many similar characteristics, do not respond uniformly to identical ""string-pulling""; therefore, much study is necessary before the desired re¬sponses can be obtained. To achieve the ultimate in accident prevention, it must be ""worked at"" constantly. Regardless of the adequacy of safety laws, rules, regulations, or standards, good accident records will not ""roll in"" if dude consideration is not given to the personal traits of those most likely to be involved in accidents."

May 1, 1948

By Ronald D. Hill, Elmore C. Grim

The cost of reclamation can vary widely, depending on the primary objectives of the restoration activities. statistics in this study originated from State files, publications, and personal communications relating to restoration and pollution control measures for previously mined lands (orphan lands) and active mines. Reclamation of orphan lands is generally considered a public burden and constitutes an economic problem. All work reported here was completed under government contract, by the lowest bidder, with money coming from State and/or Federal funds. Cost would have been substantially lower had the reclamation been concurrent with mining. Several persons connected with some of the projects have observed that costs could probably be reduced by at least one half, if the reclamation had been conducted along with the mining. The expense of clearing and grubbing of volunteer vegetation, disposal of buried trees and brush, loosing of compacted spoil, and re-establishing access to areas could be saved. In addition, a contracting firm doing the work for a government agency would have mobilization costs and receive a profit. Mining companies also are profit conscious and would consider these costs in anticipating their profits (e.g., overhead would be less if reclamation is integrated with mining). The data presented here should serve as a guide for estimating and determining cost ranges, however, it should be recognized that variations exist. Adjustments may be necessary from the standpoint of physical conditions, economic conditions, price changes, and more restrictive requirements of recent surface mining laws. Reclamation conditions, procedures and successes in the eastern United States, particularly in Appalachia, have no bearing on conditions to be expected in the western United States. The situations are wholly different. Reclamation in the West differs from th t in the East, primarily because of aridity especially a during the summer months 1). Because of the many variables and differences between reclamation in eastern and western areas, they will be discussed separately.

Jan 1, 1974

Improve surface mine haul-age truck safety and efficiency by providing a means for sensing the weight and distribution of the truck&apos;s load. Approach The safety hazards and the economic implications of overloading mine-haulage trucks were analyzed to determine the net effect of that practice on mine operations. The analysis indicated that: Ten to 25 pct overloading is typical; Higher haulage, tire, and maintenance costs occur due to overloading (a 20 pct overload was estimated to increase operating costs 7 pct per ton); Ten to 15 pct of haulage? truck injuries and fatalities are attributable to overload conditions, at a cost over one million dollars per year to the mining industry. Vehicle-weighing technology that conformed to the performance specification for an off-highway haulage truck overload detection system was selected for in-mine testing. How It Works Normally, volumetric estimates are made during the loading sequence which do not account for the varying ore density. Hence, the actual weight of a load is never precisely known. By providing a precise measurement, an overload detection system will not only indicate vehicle overloading, but will also show under-utilization of the truck. One system tested by the Bureau of Mines was the ?Load Analyzer" manufactured by Pactronics Corporation in California. This system consists of a meter-type analog readout for the cab console and three "Electrosensors" (linear variable differential transformers) attached to the main frame. Using conventional welding and brazing techniques, two sensors are attached between the front members of the engine sub-frame and the top of the left and right trailing arms (one sensor per arm). The same techniques are used to attach the third sensor to the rear centerline of the truck. between the main frame cross member and the A-frame. The readout unit on the cab console indicates by color-coding whether each sensor loading is under (green), at (yellow), or over (red) the pre-set rated load. The three-sensor configuration with in-dependent readouts also detects uneven distribution of the load.

Jan 1, 1984

By Michael G. Zabetakis

The process of ?gasfreeing? has been defined3/ as "* * * the removal of oil and vapors from tanks, pipelines, and compartments to render such spaces safe for the intended work," Generally, part or all of a vessel is gasfreed for one of several reasons: Periodic cleaning; tank inspection or repairs; shipyard overhaul or major repairs; or change of cargo, Curing the gas- freeing, flammable or explosive4/ mixtures (mixtures through which a flame can propagate after ignition by an open flame, heated object, electrical charge, or other means) may be produced. These mixtures create an explosion hazard, as the pressures produced after their ignition are often great enough to completely demolish the vessel and kill all those aboard, This paper outlines a study by the Federal Bureau of Mines of the gas explosion hazards likely to be encountered while gasfreeing a vessel compartment. To better understand these hazards it will first be necessary to review the language used in gas- explosions work. This language is considered in the following sections. Inert gases such as carbon dioxide, nitrogen, water vapor, and others can be used to decrease the range of combustible-vapor concentrations in which flammable mixtures are formed. Sufficient quantities of such gases can often be added to cause a mixture that originally was flamable to become nonflammable. Unfortunately, the use of water vapor in this application is complicated by the fact that elevated temperatures are required to keep the water in the vapor state. In practice, it may be difficult to maintain these elevated temperatures throughout the space (such as a cargo tank) to be inerted for any length of time. Accordingly, where other inert gases are not available, it may be desirable to gasfree a Lank by using heated air. To do this, the combustible vapors should be flushed as quickly as possible from the space to be gasfreed. In a properly designed system, large tanks were gasfreed with a littlee as 6 volumes of air per volume of tank capacity.

Jan 1, 1961

By R. E. Campbell

Uranium metal of improved purity was prepared by electrorefining commercial magnesium-reduced uranium in a molten sodium chloride-uranium trichloride electrolyte. The best operating conditions for the preparation of refined metal were established as follows: an electrolyte containing 8.7 to 13.3 weight-percent uranium; initial cathode current densities from 300 to 1,500 amp/sq ft; and a molten salt temperature of 860° C. Ingots produced from electrorefined uranium crystals prepared with these operating conditions were substantially free of metallic impurities. The only impurities in the refined and consolidated metal were present in low or undetectable amounts.

Jan 1, 1965

By Ervin P. Fuchs

Volume II of this report presents the vibration data, octave band data, one-third octave band data and narrow band (amplitude versus frequency) data for ten mining machines. These ten mining machines include a Goodman 968-2 Loading Machine, a Lee Norse 245 Continuous Miner, a Jeffrey 120L Continuous Miner, a National Mine Service 3080 Continuous Miner, Acme D-1 Roof Bolter, a Lee Norse 265 Continuous Miner, two Jeffrey Locomotives, a Joy CD-71A Coal Drill and a Jeffrey 100L Auger Miner. Volume J of this report presents the effects of underground environment and loading conditions on noise levels of coal mining equipment

Jan 1, 1979

By Robert H. Ridgway

Scrap iron and steel attracted attention during 1937 because of the unprecedented exports and the concomitant agitation in some quarters to prohibit the exportation of this essential raw material except on license by the President. This report does not attempt to analyze the statistics given in the light of the controversy over the limitation of scrap exports, but it is believed that students of this problem will find many essential basic data in the various tables presented herein. This paper presents the results of the third in the series of annual canvasses on the consumption of ferrous scrap and pig iron in the United States. The study was inaugurated in 1935 by the Bureau of Mines in response to requests from trade organizations and others for detailed

Jan 1, 1938

By Robert H. Ridgway

Scrap iron and steel attracted attention during 1937 because of the unprecedented exports and the concomitant agitation in some quarters to prohibit the exportation of this essential raw material except on license by the President. This report does not attempt to analyze the statistics given in the light of the controversy over the limitation of scrap exports, but it is believed that students of this problem will find many essential basic data in the various tables presented herein. This paper presents the results of the third in the series of annual canvasses on the consumption of ferrous scrap and pig iron in the United States. The study was inaugurated in 1935 by the Bureau of Mines in response to requests from trade organizations and others for detailed

Jan 1, 1938

By R. R. Wells

As a part of the strategic minerals program of the Bureau of Mines, nine chromite-ore samples were obtained during the period 1949-56 from mines in the vicinity of Red Mountain, near Seldovia, Kenai Peninsula, Alaska. This report summarizes the results of beneficiation studies of the samples at the Bureau&apos;s Juneau, Alaska, and Albany, Oreg., laboratories. In general, the ores were found amenable to concentration by gravity methods for producing concentrates that assayed over 48 percent chromic oxide. Intimate association of chromite and gangue minerals, however, necessitated fine grinding and limited the amount of chromite recoverable. Recovery of chromium in concentrate that assayed 48 percent chromic oxide or higher ranged from approximately 20 percent for low-grade ores (10 to 12 percent Cr203) to more than 95 percent for 1 high-grade sample (42 percent Cr203). The iron content of the chrome-bearing mineral -hence, the chrome/iron ratio of finished concentrate -appears to vary with the grade of the ore. Concentrates made from high-grade ores had chrome/iron ratios as high as 3.1:1; the concentrates from low-grade ores, however, had chrome/iron ratios as low as 1.8:1.

Jan 1, 1957