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By James H. Scott

A technique of seismic refraction data analysis has been developed in which a digital computer is used to generate a two-dimensional model representing a layered-earth depth interpretation. Travel times are picked on seismic records by the human interpreter. These times, together with shot point and geophone locations and refraction layer control information, are submitted to the computer on punched cards. A first approximation delineation of each refraction horizon is obtained by a computer adaptation of the delay-time method. The approximation is then tested and improved by the computer through the use of a ray-tracing procedure in which ray travel times computed for the model are compared against field-measured travel times. The model is subsequently adjusted in an iterative manner so as to minimize the discrepancy between computed and measured travel times. The Fortran program is listed in the appendix of the report together with instructions for preparing data cards and examples of results.

Jan 1, 1972

By T. H. Miller

This piper is a continuation of a series of yearly review articles started in 1925 by Thomas Varley. The development of flotation has been rapid, and better understanding of the functions o' flotation reagents has resulted in many changes in the kinds and quantities o reagents used. It is the purpose of this report to present the information in such a manner as to be of value to the milling industry as well as to the manufacturer of flotation reagents. These data have been compiled from a. survey of approximately 250 flotation plants of all classes within the United States. Many of these plants made complete reports of their operations, out others were apparently unable to supply this information in sufficient detail to meet the requirements of this investigation. Although it is realized that the data obtained in this survey are not as full as they should be to render the greatest service possible to the milling industry, it is hoped that succeeding articles will include complete information regarding milling; conditions and recoveries. As in the past, every effort has been made to conceal individual plant operations. RESULTS OF INVESTIGATION Table 1 gives the tons of ore treated by gravity and flotation methods and the concentrates produced as reported by 208 plants. The totals of 77,043,535 tons of ore and 4, 596,640 tons of concentrates from this table compare with totals of 78,973,012 tons and 4,683,972 tons respectively (furnished by the Bureau of Mines, Division of Mineral Statistics), indicating that the milling survey is about 98 per cant complete.

Jan 1, 1930

By Wing G. Agnew

[This report presents the results of tests made by the Mining Division, Bureau of Mines, on the relative durability of manganese-steel drill rods and carbon-steel drill rods for use with detachable bits.]

Jan 1, 1941

By R. Hogg, T. F. Dumm

"There is a considerable need for standardized respirable dusts with consistent, reproducible characteristics which simulate those of actual mine dust. The availability of such materials should be a significant factor in promoting coordinated research into dust characterization and mine monitoring, dust control, and the biomedical aspects of dust toxicology. The use of an opposed-jet, fluid-energy grinding system in closed circuit with a cross-flow, centrifugal air classifier for preparing bulk quantities of respirable-size dust has been investigated, and appropriate, standardized procedures have been established. By stage-crushing, screening, and fine-grinding with a Donaldson Acucut classifier/mini-grinder system, it is possible to produce bulk quantities of respirable dust at relatively high rates. Using minor modifications to the system, broader or narrower size distributions can be prepared within the respirable range. The system has been shown to reach steady-state with respect to product size distribution very rapidly. However, preferential grinding/classification effects appear to lead to a slow build-up of mineral matter in the circulating load with a corresponding slow change in product composition with time. In those applications where the dust composition is required to match that of the feed coal, it may be necessary to allow considerable time for a true steady-state to be established.Standard respirable dust samples have been prepared from coals representing the western (high volitile A bituminous), central (medium volatile bituminous) and eastern (anthracite) mining areas of Pennsylvania. Quartz and kaolin clay samples, representing important mineral constituents of coal dust have also been prepared. Extensive characterization studies have been performed on the samples to evaluate chemical and mineralogical composition and the distributions of particle size and specific gravity. Detailed information on the original coals is available from the Penn State Coal Data Base. The standard coal dust samples appear to simulate actual mine dust very well with respect to particle size and shape, but generally have somewhat lower ash content. Samples of these standard dusts have been made available to research groups concerned with respirable dust in mines."

Mar 1, 1989

By N. A. Eilertsen

Eastern Aroostook County, Maine, contains an enormous tonnage of manganese widely distributed in manganiferous sedimentary beds composed of hematitic shale, hematitic slate, and laminated siliceous carbonate rock. The bedded deposits range in thickness from several feet to over 150 feet. Manganese minerals that occur as silicates and carbonate are so minute that they cannot be concentrated by present methods of ore dressing. From a hydrometallurgical standpoint, the deposits can best be classified by amenability to acid leaching. The deposits of Aroostook County are in three geographical groups (see fig. l), designated as the northern, central, and southern districts. At least 13 deposits are known to occur in the latter district, which covers an Ewes about 8 miles wide and 15 miles long. The Littleton Ridge deposit, on the northern boundary of the southern district, previously examined by geologists from the State and Federal Geological Surveys on the farms of Donald H. Haggerty and David A. Abernethy, was pointed out in reports as being possibly the richest and largest in the southern district. The Bureau of Mines sampled this deposit by surface trenching and diamond drilling from May 1 to September 30, 1951. A total of 23 trenches was bulldozed, aggregating 5,355 linear feet, of which 8 trenches were sampled by cutting 185 channel samples over a linear distance of 1,820 feet.

Jan 1, 1955

By Raymond B. Ladoo

"The talc and soapstone deposits of Vermont have been worked more or less continuously for nearly 100 years, but all of the early efforts seem to have been directed toward the production of slabs for foot warmer, and other similar uses. Altho soapstone of good quality occurs at several places, much of the material first utilized was really talc and was not massive enough to be cut successfully. The grinding of talc in Vermont seems to have commenced in about 1902 and has shown continuous growth since that time. Statistics compiled by the Geological Survey in Mineral Resources of the ,United States show that the production of talc in Vermont has increased, from 8,978 short tons valued at $65,525 in 1905 to 93,960 short tons valued at $625,150 in 1917. Until 1917, New York was the leading producer in both tonnage and value with Vermont second, but in 1917, Vermont took the lead in tonnage produced, although not in value, with a production of over 47% of the total tonnage produced in the United States and over 35% of the world's pro-duction. This increase in production will probably be continued, though possibly at decreased rate, for the reserves of talc In Vermont are large.Active talc mines and mills in Vermont are found in four districts: Chester, Windsor County; Rochester, Windsor County; Waterbury, Washington County; and Johnson, Lamoille County, These mines and mills are distributed as shown in the following table:While there are a great many other known deposits of talc and soapstone in Vermont, some of which have been worked, those listed above are the only ones which have survived and are producing on a commercial basis. The closing down of many mines and quarries, for example, those at Perkinsville, Stockbridge, Reading, Cavendish, and Athens, has been attributed to several causes. Of these causes the most important seem to be exhaustion of the deposit, poor grade, long haul to the railroad, poor management due to lack of knowledge of mining methods and failure to consider talc mining strictly as a business proposition. The companies which are now operating with greatest apparent success are those which have realized the present and future possibilities of their industry, and have invested sufficient capital in both equipment and personnel to establish their companies on a firm business basis."

Sep 1, 1919

By L. A. Stinnett

An investigation of hazardous surface openings of abandoned and inactive underground mines in the Black Hills area of South Dakota has revealed: (1) tracing legal ownership of mineral claims via county courthouses is confusing, complex, and oftentimes misleading, (2 ) in general, the selected mine openings in this investigation are to be considered relatively high in risks and hazard potential which poses a threat to the general public, (3) mine closure procedures and designs can generally be categorically implemented depending on the overall situation of the particular mine opening with subsequent unit costs' estimates, (4) few preventive state or federal legal measures exist to date concerning mine closures, and (5) liability damages relating to mine opening accidents usually involve expensive and complex common law cases.

Jan 1, 1979

By Cloyd M. Smith

Progressive mine management is placing increased emphasis on improved ventilation as a contribution to better safety , health , and productivity of miners . Management is on the alert for means of bettering the working environment by increasing the flow of air and distributing it more effectively to the working places , having in mind the necessity of avoiding exorbitant ventilation costs . A basic need in planning betterments of this kind is knowledge of existing rates of flow and air pressures , infCoorrmmaattiicon that is supplied through ventilation surveys . Some companies make partial surveys from time to time , but few make complete surveys on a routine basis . This report describes the practice of a large British anthracite -mining company , which operates 24 collieries in South Wales , in carrying out a routine program of ventilation surveying . Ventilation characteristics and climatic conditions in the working places of its collieries are determined at frequent intervals with a view to increasing the effectiveness of ventilation and protecting the health of workers . It is thought that many of the points of the procedure used in making the surveys and in compiling and reporting the results will be applicable to American practice and that a discussion of the program may be helpful to colliery managers who are planning similar work .

Oct 1, 1949

By Daryl R. Tweeton

The Bureau of Mines conducted experiments to measure the influence of environment on the friction and wear of a steel-quartz system at several speeds and loads. In each test a quartz block was pressed against a rotating ring of low-carbon steel. Environments used were moist air, dry air, dry nitrogen, water, aqueous oleylarnmonium acetate (ClsH35NH3+-OCOCH3), and aqueous aluminum chloride (A1C13). The sliding speeds were 2.2, 13, and 33, cm/sec, and the loads were 6.8 and 13.6 kg. The coefficient of friction, the wear, and the roughness of the surfaces were measured, and the wear debris was examined. The coefficient of friction was significantly lower in moist air at 2.2 cm/sec than for any other combination of environment and speed employed, and was generally an inverse function of the oxidizing ability of the environment. The coefficient of friction increased somewhat with increasing load. The wear of the steel rings was greatest in dry air at all speeds and loads. The wear of the quartz blocks at 180 rpm was greatest in dry air, but at 12 rpm it was greatest in nitrogen. Friction and wear in aqueous oleylarnmonium acetate and in aqueous aluminum chloride were similar to effect in water alone.

Jan 1, 1976

This publication contains 10 papers presented at a symposium on ATRS systems in Charleston, WV, on June 23, 1983. Included are papers by MSHA Technical Support (Roof Control), West Virginia Institute of Technology, the Bureau of Mines, and seven roof bolter manufacturers and/or designers of ATRS systems. These papers summarize the most recent developments in ATRS technology and can serve as a guide to potential designers, developers, and users of ATRS systems.

Jan 1, 1985

By H. F. Yancey

The Baum-type jig used so widely to clean bituminous coals has not been adopted for anthracite. If proved suitable for anthracite, its use might lower preparation costs in some plants. Cleaning trials on a Pennsylvania anthracite in a laboratory-size Baum-type jig were undertaken by the Bureau of Mines to provide indicative information that would be helpful in determining whether the cost of a full-scale installation would be justified. Clean coal surpassing standard anthracite specifications was obtained in all sizes from Stove through No. 5 Buckwheat. Recovery effi¬ciencies were acceptable down to 3/16-inch size, but there was excessive loss of coal in the finer sizes. Thus the fine refuse produced in a commercial plant might re¬quire retreatment. A comparative cleaning trial in a dense-medium pilot plant provided a recovery efficiency only l percent higher than obtained in jigging.

Jan 1, 1957

By H. E. Perlee

Autoignition temperatures and limits of flammability of nine halogenated hydrocarbons in atmospheres of air, oxygen, and nitrogen tetroxide were measured in a modified standard autoignition apparatus and limit-of-flammability apparatus previously developed at the Bureau of Nines. Of the nine halogenated hydrocarbons investigates--bromochloromethane, bromotrifluoromethane, bromochlorodifluoromethane, 1,1,2-trichlorotrifluoroethane, 1-bromo-l-chloro-2,2,2-trifluoroethane, dibromodifluoromethane, l,2-dibromo-1,1,2,2-tetrafluoro-ethane, 1,1,1,3,3-pentachlorotrifluoropropane, and l-bromo-2,4-dichloro-1,1,2, 3,3,4-hexafluorobutane--two formed flammable mixtures with nitrogen tetroxide and six with oxygen; none formed flammable mixtures with air. Three of the halogenated hydrocarbons formed no flammable zones with any of the three oxidizing atmospheres. For those halogenated hydrocarbons that supported combustion in oxygen atmospheres, explosion pressures developed during constant-volume burning of mixtures near the middle of the flammable zone were observed to range from about 6 psig for dibromodifluoromethane to 158 psig for 1-bromo-1-chloro-2,2,2-trifluoroethane. In all cases, the calculated burning velocities of these mixtures were less than 8 in/sec.

Jan 1, 1966

By F. W. Lee

The paramount importance of water to life of all forms on the earth is too well known to require elaboration in this brief paper. It has repeatedly been termed the most valuable of all our mineral resources. Its importance is justifiably recognized in the extensive areas covering the earth which receive sufficient rainfall to sustain a relatively luxuriant vegetation; but in those areas where rainfall is insufficient to support anything but a relatively meager plant growth, the location of a water supply and its development become of even more vital interest to those attempting to obtain a living from the soil. Geological investigations concerning the water supply of the United States have been most extensive, important work having been accomplished by Federal, State, and local governments and by private enterprise. A casual examination of the titles of the 739 Water-Supply Papers published by the United States Geological Survey3/ alone testifies 'to the vital nature of our water resources and the extensive work that has been done on them.

Jan 1, 1936

By T. E. Gray

This report describes the preparation characteristics of the significant coalbeds in Harrison County, W. Va. It is one in a series of Federal Bureau of Mines reports planned to determine coals suitable for the production of metallurgical coke, either as mined or after beneficiation. Over 6.5 million tons of coal was produced in Harrison County, W. Va., in 1958, of which over 3.7 million tons was cleaned mechanically in seven preparation plants. All of the coal cleaned was from the Pittsburgh bed. It has been estimated that more than 1,816 million tons of coal remains in the county in beds 12 inches or more thick. The Pittsburgh and Redstone beds were selected by the Bureau for a study based on current production rates and estimated minable reserves. Sample locations were selected following a study of the literature, conferences with mining engineers and mining company officials in the field, and examination of the available sites. Six samples were collected from the Pittsburgh bed, and three samples came from the Redstone bed, Float-and-sink tests of the samples collected from the Pittsburgh and Redstone beds showed that neither coal could be upgraded to a metallurgical fuel under the standards set up for this study, even after intensive preparation. Finer crushing of the samples moderately increased the yields and slightly reduced both the ash and the sulfur contents in the 1.30-specific-gravity float fractions. Finer crushing slightly decreased the yields in the 1.58-specific-gravity float fractions, whereas it reduced the sulfur content 0.11 percent for the Redstone sample and 0.46 for the Pittsburgh sample.

Jan 1, 1961

By Scott Turner

Many of you radio listeners have probably never seen a mine . You may be glad of it, but you should not forget that there is a vast army of men in this country who not only have to see mines , but have to work in them day by day in order that you may be supplied with many of the things you need. Specifically , nearly a million men work in the mines of the United States , 700,000 in the coal mines , 110,000 in the metal mines , 100,000 in other mines and quarries , and 75,000 in the oil and gas fields . On a stormy night , the average citizen is apt to think of the perils of the seaman . Particularly in the old days before steamships , many a prayer went up " God help the poor sailor on a night like this . " At the same time , the sailormen often expressed fear for the poor landlubber , exposed as he was to the danger of falling chimneys , swaying signboards , and uprooted trees . So with the miner . Many of you may pity him , for working underground in complete darkness except for feeble artificial lighting , mining coal or ore , drilling hard rock , handling explosives , and perhaps breathing vitiated air . On the other hand , on stormy days , with rain , snow or hail falling , and with the temperature low , or on hot bright days , I have often heard miners joke about the poor fellows who had to stay " on top, " and could not get " down below" where there was no wind , where no snow fell, where the temperature was unchanging , and where a man could have his own working place , arranged to suit himself , with little interference from meddlers and with no automobiles to dodge . So do not feel too sorry for the miner . He is quite apt to be a strong , healthy , hearty person , making pretty good wages , and fairly well contented with his lot .

Dec 1, 1930

By Nadia C. Miller

In situ stope leaching is an innovative mining system that reduces the surface impacts of conventional underground mining. As in any leaching operation, stope leaching requires hydrologic site characterization and control of leaching solutions. Several tracer tests, using sodium chloride (NaCl) in various concentrations, were conducted by the U.S. Bureau of Mines (USBM) in an underground experimental stope to simulate a leaching environment. The tests were conducted in fractured crystalline rock that was partially water-saturated. As tests progressed, the surrounding fractures became more saturated. A predominant flow direction away from the stope was found during testing. Testing procedures, results, and a remediation plan for in situ leaching based on field observations are presented in this report.

Jan 1, 2010

By Bernard J. Steblay

The U.S. Bureau of Mines has attempted to use ultrasonic signal travel-time measurements to measure loaded roof bolt strains. The strain measurements are then related to roof bolt loads through equations or empirical calibrations. Such techniques offer the potential of accurate, rapid bolt load measurement that does not disturb the anchotage. This report presents 6e research findings for a specific type of ultrasonic measurement instrument using a pulsed-phase-Iock-Ioop technique. This technique measures signal travel time indirectly by measuring frequency changes. A complete development of the applicable theory and detailed derivations of key equations is presented along with empirical laboratory and field results. The differences between anticipated and measured behaviors are analyzed and discussed. The report identifies problems encountered in applying pulsed-phase-Iock-Ioop technology to roof bolt load measurement and provides potential solutions to many of them. A key assumption of pulsed-phase-lock-loop theory is that driving and reflected signal frequencies will always be equal. Findings showed that not only were actual frequencies not equal but they were not stable or simply related. Reflection wave shape also was not stable. The ramification of these findings and ways to minimize their adverse effects are presented.

Jan 1, 1990

By R. V. Ramani, R. Bhaskar

"The control of respirable dust in mines has been given paramount importance due to the health and safety implications associated with fine dust. The understanding of the temporal and spatial behavior of dust has been recognized as essential for increasing the efficiencies of the existing control techniques and for developing new control strategies. Mining-related studies in this area are, in general, limited. They are also mostly experimental. Some mathematical and computer analyses have been attempted. In this paper, first a review of the mathematical studies performed in the last three decades in this area is presented. Second, a mathematical model for analyzing dust flow in mines is proposed. The model takes into account a number of factors affecting dust transport. It incorporates varying dust generation source strengths and dispersion, deposition, and coagulation of dust in mine airways. Finally, application areas for the model are discussed. A computer program based on the mathematical model has been developed. The program will output the dust concentration in the mine atmosphere as a function of time and distance from the source. The amount of dust deposited on the sides, roof, and floor of the airway is also determined.IntroductionAn airborne dust cloud is a complex system containing particles of varied size, density, shape and state of aggregation. The behavior of the particles is dependent on a number of complex physical mechanisms, often opposing in nature. The net interaction results in the ambient concentration. This size dependent behavior of particles contrasts with that of gases, an area quite widely studied.The term aerosol is used to describe clouds of microscopic and submicroscopic particles in air such as chemical smoke or particulate matter released from smoke stacks. An aerosol system can be regarded as an arbitrary element of volume filled with gas and suspended particles of possible highly variable physiochemical nature. The parameters that are used to describe an aerosol system include concentration, mass average velocity and particle mass and radius. In characterizing such systems, several assumptions are made. Among these is the assumption that particles are smooth, inert and rigid spheres. Again, for example, when the particles are in transport, the possibility of collision exists. As a result of the collision, the particles may coalesce to form larger particles. The probability of sticking is considered a known quantity (lady, 1970). In this paper, the application of the principles used in aerosol systems is explored for the study of the transport and deposition of fine coal dust in underground mines."

Jun 1, 1988

By Michael D. Balen

This Bureau of Mines open file report is one in a series of reports written about the Valdez Creek Mining District (VCM D) as a result of the continuing Bureau of Mines mining district evaluation program. This report presents the results of order-of-magnitude mining feasibility studies. The mining feasibility studies were conducted for mineral deposit models that were based on real and hypothetical deposits that occur in the VCMD. A total of 6b mine models were developed for application to the mineral deposit models. The goal of the feasibility study was to determine the monetary value per unit of minable ore that would cause the simulated cash flow for each of 66 mine models to achieve certain pre-defined rates of return for the invested capital.

Jan 1, 2011

By W. L. Crentz

San Juan County, which occupies the extreme northwest corner of New Mexico, contains large reserves of coal in the Fruitland formation and in the Menefee formation of the Mesaverde group. The coals have bright luster, are brittle, and break easily in handling. All mines sampled are in the La Plata-Fruitland and Rio Chaco districts of the Durango-Gallup coal field. This large area, all within San Juan County, contains numerous coal beds 5 to 15 feet thick. Ellis2/ mentions the Carbonero (Fruitland in this report) bed in the La Plata-Fruitland district attaining a thickness of 36 feet. This bed has been correlated with the Carbonero bed, formerly mined at Carbon Junction, near Durango, Colo. During the field investigation covered by this report, no operating mine in the Fruitland bed was working a bed thickness of more than 15 feet.

Jan 1, 1957