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By Arcy, D&apos Banister

The productive potential of the Nation's principal active and inactive silver mining districts has been evaluated, using 1964 economic conditions and assumed silver prices ranging up to $3 per ounce. On this basis, the United States has an estimated 5 billion ounces of unmined silver, excluding minor byproduct silver in gold deposits. Approximately 3.5 billion ounces are contained in deposits requiring higher silver prices to be economically minable, and about 1.3 billion ounces are in currently operating mines. An analysis of silver consumption trends since 1954 indicates that the free world industrial market will climb to nearly 800 million ounces annually by 1985. U.S. industrial silver consumption has been projected to increase at an annual rate of 4 percent from 1965 to 1985. Average annual increase for the remainder of the free world has been 8.1 percent since 1953; this is expected to level off with an estimated average increase of 5 percent to 1975 and 4 percent from 1976 to 1985. Foreign silver production has, in the past, exceeded consumption, but in 1960 the supply deficit was over 100 million ounces. U.S. production, also traditionally exceeding demand, was suddenly overtaken at the start of World War II. By 1964 the annual deficit, excluding coinage, was over 84 million ounces. World coinage requirements of silver are fast declining and expected to total only 25 million ounces annually by 1985. In fact, coins are already becoming major short-term source of silver to fill the large deficit between industrial demand and current production. The larger, long-term deficit (to 1985, the limit of this study) must be balanced by silver from the hoards and new production from silver deposits. Eventually all of the deficit must be met by new production or silver prices will rise until consumption is greatly curtailed. To balance free world supply and demand, it is estimated that the free world must produce an additional 85 million ounces by 1975 and 375 million ounces by 1985. The estimated proportion expected from U.S. deposits is 17 million ounces by 1975 and 74 million ounces by 1985.

Jan 1, 1969

By J. H. Daniel

This report, summarizing the results of two studies sponsored by the Bureau of Mines, presents information on the types of mobile machines used in surface coal mines in the United States, and the amount of noise to which miners are exposed. Data consist of a calculated value of the probability of noise overexposure caused by specific equipment. These data are extrapolated to estimate the number of overexposed operators. Bulldozers were identified as the major contributors to noise overexposure, and the report presents results of a Bureau-funded program on the feasibility of providing retrofit noise control on bulldozers.

Jan 1, 1980

By Edward F. Divers

This Bureau of Mines report describes a new type of scrubber (dust collector) and ventilation system built into the auger support frame (boom) of a Jeffrey 120L continuous mining machine. With this twin scrubber arrangement, one scrubber is mounted into each side of the boom. Each scrubber includes a 2,500-cfm fan, a flooded fibrous-bed scrubber panel, and a water droplet eliminator. The system was designed for minimum size and adds only a few inches to machine height. Exhaust duct design allows flexibility with various airflow configurations to suit both blowing and exhaust fare ventilation systems and brattice distances ranging up to 20 feet. Full-scale tests with exhaust ventilation were conducted at a Mine Safety and Health Administration surface facility at Bruceton, Pa., to determine the scrubbers' methane dilution capability. Several configurations of the twin scrubber-ventilation system produced striking improvements in face methane dilution when compared with conventional systems.

Jan 1, 1981

To permit better cap lamp positioning for users of dust helmets. Approach The present design of the dust helmet prevents use of the miner's cap lamp when the front shield is raised, When the shield is raised I the cap lamp is directed at the mine roof or back, making the lamp useless in the event the miner needs to wear his self-rescuer. A flip bracket was designed by the Bureau of Mines to correct this situation. How It Works The safety hat is modified by the addition of lamp clips, a bracket and a hinge on the cap lamp and face shield. Two clips hold the lamp cord firmly to the helmet. When the safety hat shield is raised, compressive force from the lamp cord causes the cap lamp hinge to swing open about 90%, allowing the lamp

Jan 1, 1984

The Bureau of Mines annually publishes statistical data reflecting technological trends in the minerals industry (metals and nonmetals except fuels). This report outlines recent developments and trends and the technology outlook for mining practices and metallurgical processing based on a review of the minerals industry during the past 2 years. A historical statistical series which indicates trends in the minerals industry has been extended with 1970 data. In addition, data are given from a 5-year Bureau of Mines cyclic canvass of froth flotation plants. Data for 1970 are compared with those of 1960 and 1965.

Jan 1, 1972

Reduce permanent hearing losses to bulldozer operators. Approach Two types of noise control packages have been developed, that can be readily fabricated and installed into bulldozers by mine personnel. How It Works Both of the noise control packages reduce the noise exposure of the operator by two techniques, blocking the noise paths or absorbing the sound before it reaches the operator. Both airborne noise paths and noise paths through the machine are blocked. One noise control package is designed for bulldozers having ROPS (Roll Over Protection System), but no cab. The other package is designed for bulldozers having ROPS

Jan 1, 1981

By D. W. Frommer

Laboratory mineral-dressing investigations were conducted on talc-bearing samples from Arkansas and Texas under the Bureau of Mines program of examinations and surveys, which is concerned, in part, with the improvement of conservation and utilization of domestic mineral resources. Two of the soapstones in question were successfully upgraded by flotation, utilizing stage additions of a frother and an amine to promote their talc content. The process could enable the producers to meet more rigid specifications of higher priced talc commodities. INTRODUCTION Talc is an industrial mineral with distinctive properties, such as softness, smoothness, large surface area in relation to mass, chemical inertness, and good retention as a filler, that make it particularly valuable to a number of industries. Sales to 6 industries -ceramics, paint, insecticide, rubber, roofing, and paper -consumed 84 percent of the domestic production of talc, pyrophyllite, and ground soapstone in 1952. Mine production in that year totaled 600,908 tons. Sales of crude and ground material were 593,147 tons valued at $11,347,317.2/

Jan 1, 1956

By R. E. Brewwe

"INTRODUCTION Anyone who has had frequent occasion to compare methods of analysis and testing as employed in European countries with those used in the United States has felt the need of a table or graph giving the relationship between the units of measurement of finely powdered materials. Most of the few published comparisons include only two series of sieves and often require tedious interpolations to adapt the data of one series to the series more familiar to the reader. To eliminate such deficiencies, the author hopes that the discussion and comparison of fine-series sieve sizes presented here will conserve the time of interested research workers.ACKNOWLEDGMENTSThe author is deeply indebted to Virginia B. Strathearn, scientific aide, for help in compiling the information from the literature and to W. A. Solvig, senior chemist, for valuable suggestions in preparing the manuscript.SQUARE-MESH-SIEVE SERIES OF DIFFERENT COUNTRIESSieving analyses of powdered materials have been placed on a comparable basis in different countries by the introduction and adoption of standard sieve-scale series. Series of wire-cloth square-mesh sieves in common I oratory and industrial use include: Institution of Mining and Metallurgy standard laboratory screens (I.M.M.); British Standards Institution standard for fine-mesh test sieves (B.S. or B.S.I.); Tyler standard sereer-scale sieves; United States standard sieve series; Deutsche Industrial-Nermen (DIN); and the standard control sieves of the Association Francaise de Normalisation (AFNOR). With the exception of the I.M.M. series in which the opening is equal to the diameter of the wire, the general proportions of the various series of sieves are similar. The size of British and American sieves is designated by the number of meshes or openings per linear inch or, more recently, by the number of microns per linear sieve opening. In a technical sense the word ""mesh"" is meaningless, unless the diameter of the wire is also given, so that the size of the opening can be determined. On the Continent sieves are designated either by the nunber of Mesh per linear centimeter or by the number of openings per square centimeter."

Jul 1, 1944

By James R. McVey

Tests during pillar robbing, longwall operations, and other mining activities indicate that roof-floor convergence rates can be used as an indicator of imminent roof failure. A large number of electrical-mechanical devices have been built to measure convergence as well as convergence rates, but most obstruct mine traffic and are costly and time consuming to install. The Bureau of Mines has designed and is evaluating three types of small ultrasonic units to make these measurements. The new instruments provide nonobstructing measurements up to 35 ft away. The ultrasonic transducers can be attached to a roof bolt, placed in an unsupported area (by means of a toss basket), or handheld. Total distance to the target and rate of closure are displayed digitally to 0.001 ft and 0.01 ft/min, respectively.

Jan 1, 1984

By L. D. Patts, G. H. Schnakenberg

Achieving substantial reductions in the exposure of underground miners to diesel particulate matter in a number of metal and nonmetal mines in the U.S. depends on the ability of the industry to widely implement advanced diesel emissions control technologies, primarily diesel particulate filter (DPF) systems. Recent field studies showed that diesel particulate filter systems with Cordierite and silicon carbide ceramic filter elements are capable of reducing concentrations of diesel particulate matter and elemental carbon by more than 70 and 90 percent, respectively. But those studies and several other attempts to implement DPF systems in underground mines revealed a number of relatively unique technical and operational challenges that are limiting industry-wide implementation of this technology. This paper provides detailed analysis of some of those challenges and short overviews of several projects launched by NIOSH Pittsburgh Research Laboratory in an attempt to provide the underground mining industry with more adequate DPF systems. These systems employ advanced technologies to overcome the most pronounced challenge, the regeneration of DPF elements installed on mining engines that generate relatively low exhaust temperature. This paper presents essential findings obtained through a long-term evaluation of DPF system with diesel fuel burner technology installed on a heavy-duty load-haul dump vehicle in an underground metal mine. In addition, the essential results of the laboratory evaluation of a popular on-highway DPF system which was adapted and optimized for underground mining applications will be summarized in this paper.

By William L. Crentz

Pike County in the easternmost portion of Kentucky is one of the major coal-producing areas in the eastern Kentucky coal field. The county contains numerous coal beds, many of which are too thin to support mining. The commercially important beds are usually 4 feet or more thick, but selective mining at some places calls for removal of a much thinner section of the bed. The variation in quality of the beds from place to place and the large number of coal beds make correlation uncertain. Samples were collected from 14 different coal beds, of which the Elkhorn group is by far the most important. In addition to the Upper Elkhorn No. 3, Upper Elkhorn No. 2, Upper Elkhorn No. 1, and Lower Elkhorn beds that comprise the Elkhorn group, the Winifrede, Williamson, and Bingham beds constitute the principal coal deposits in Pike County.

Jan 1, 1952

By G. R. Fitterer, C. H. Herty

"INTRODUCTION Manufacturers and consumers of steel have come to realize during the past few years that cleanliness is of great importance in steels which must meet rigid specifications for various physical properties. Of equal importance is the consistent production of steel which is uniform in these properties. For maximum utility steels should be uniform not only from heat to heat, but also from ingot to ingot and within each ingot. In the manufacture of killed steels such as the higher carbon forging grades, uniformity as indicated by the usual chemical analysis in easy to obtain, provided that a normal top discard is taken, as is always the case in steels poured with hot—top practice. No such uniformity, however, holds true for the nonmetallic matter, which consists for the most part of the products of deoxidation of the steel.For a large tonnage of steels which go into articles manufactured by deep—drawing processes, killed steel has never been successfully applied because with the present deoxidation practice, low—carbon killed steel is almost invariably extremely dirty. To obtain the desired qualities for deep drawing, the steel is rimmed, — that is to say, deoxidized with manganese and perhaps a small amount of aluminum, — the resultant product being of high purity in the skin of the ingot, but very badly segregated at the center of the ingot, particularly in the upper—central section. This segregation necessitates a very heavy top discard, and one of the major segregates is carbon which renders the steel too hard to draw properly. If clean, low—carbon killed steel could be made successfully, much better ingot yields would be obtained than by the present rimming steel practice. Furthermore, banded structures and outside and inside seams, which are undoubtedly due in a large measure to blowholes in the ingot, are defects which are very difficult to control in rimmed steel. These defects would be minimized by clean killed steel."

Feb 1, 1931

By E. E. Buban

A self-contained breathing apparatus has been developed to provide complete respiratory protection for a miner in an irrespirable atmosphere. The apparatus has the desired features of comfort, reliability, maintainability, and quick-donning capability. The apparatus is packaged in a moistureproof envelope and is protected in a shock absorbing, fiberglass resin carrying case. The apparatus is a small, lightweight, one-time-use device that can be readily worn on a miner's belt, requires no maintenance and is designed to have a shelf life of five years and a carrying life of three years. It is deployed to the use position in a period of 15 to 30 seconds. Man tests conducted in-house and at the National Institute of Occupational Safety and Health (NIOSH) testing laboratories established that this unit meets all performance requirements listed in the Code of Federal Regulations, Title 30, Part 11, Subchapter B, Subpart H (CFR 30, Part 11) for respiratory protective devices. The unit, which has received joint approval (TC-13F-37) on a prototype basis from the Mining Enforcement and Safety Administration (MESA) and NIOSH has: (1) Ten-minute service life under escape conditions. (2) Thirty-minute service life when the wearer is at rest. (3) Peak-to-peak breathing resistance of less than our inches water column height. (4) Inspired gas temperature of less than 135°F. (5) Breathing gas contents greater than 19.5 volume per cent of oxygen and less than 2.5 per cent carbon dioxin. (6) A weight (complete in carrying case) of 2.75 lbs. (7) A carrying case size of 6-1/2"x 5-1/8"x 3-1/8".

Jan 1, 1974

By L. C. IlsLey

The increasing use of Diesel engines for operating equipment on trunk-line railroads and for power-plant units has stimulated interest in the use of Diesel engines for other lines of work, among which is the possibility of substituting Diesel locomotives for trolley locomotives for mines. The possibility of developing Diesel locomotives for duty in American mines is not as remote as it might seem, particularly in view of the fact that locomotives of this type are already used in considerable numbers in European mines. A study of Diesel locomotives in Europe is contained in Report of Investigations 3320, Diesel Mine Locomotives - Development and Use in European Coal Mines, by George S. Rice and F. E. Harris.

Jan 1, 1938

By Alan R. Buehler

In 1986, at the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied part of the 256,430-acre Alvord Desert and part of the 22,240-acre East Alvord Wilderness Study Area (OR-002-074 and OR-002-073A, respectively), in order to evaluate their identified mineral resources. The study areas are located in Harney and Malheur Counties, OR, about 25 mi northeast of the small village of Fields. There are no mines, prospects, or identified mineral resources inside the study areas. Basalt flows within the study areas contain chalcedony-lined vugs and banded agate which may be of interest to rock hounds. An ignimbrite flow contains perlitic material, but crystalline contaminants make it unsuitable for commercial uses. Lacustrine (lake) sediments contain diatomite and clays, and evaporite crusts contain boron too low grade to profitably mine. Small quantities of common opal and petrified wood occur which might be of possible interest to rock hounds. Some of the petrified wood is black, free of fractures, and polishes well; it may be suitable as backing material for soft, thin, and brittle gemstones, such as precious opal. The lacustrine sediments also contain black, fetid layers which have above background, but economically insignificant concentrations of zinc, cobalt, nickel, barium, iron, manganese, aluminum, and potassium. Large quantities of fine-grained dune sands within the study areas are too far from markets for economic consideration. Ephemeral streams in the study areas contain small amounts of placer gold of no economic interest. The western portions of both study areas are reported to have moderate favorability for occurrences of natural gas, and both study areas are reported to have high favorability for the occurrence of geothermal resources. As of December 1986, oil and gas leases covered 3,100 acres in the study areas.

Jan 1, 1987

By R. L. Marek

The number of persons fatally injured in the California petroleum industry in 1931 was 30, a decrease of 20 fatalities or 40 per cent from the number killed in 1930. As a result of the decrease in the number of fatalities for 1931, the fatality curve of tie California petroleum industry reached its lowest point in nine years. Although reductions in personnel--which permitted the retention of a select and experienced class of workmen, decreased active field-development work, and curtailed production--undoubtedly have had a marked effect on reducing the number of fatalities in 1931, the decrease also has resulted from continued accident-prevention efforts. Statistics show that a direct relationship exists between development activity and the number of men accidentally killed in the drilling and producing division of the California petroleum industry. For example, when the average number of drilling wells in 1930 was 29 per cent less than in 1929, the number of men accidentally killed at drilling wells dropped 48 per cent; and when the average number of drilling wells in 1931 decreased 52 per cent from 1930, the number of fatalities at drilling wells decreased 58 per cent. The relationship between field-development work and fatality frequency is significant because each year at least 50 per cent of all the fatalities in the California petroleum industry occur in the drilling and producing division. This relationship should serve to guide the accident-prevention efforts of the industry, especially in the drilling and producing division, toward checking an increase in fatal accidents when development activity again takes an upward trend.

Jan 1, 1932

An examination of the Census of Fatal Occupational Injuries (CFOI) data for the period 1992-1995 shows that 659 fatalities occurred in the mining industry as defined by the SIC. Oil and gas accounted for slightly more than one-half of all fatalities (figure 1-1). The coal industry had the highest fatality rate for the 4-year period, with 35.6 deaths per 100,000 full-time workers, followed by metal (23.1 per 100,000), oil and gas (23.1 per 100,000), and nonmetal (20.1 per 100,000). The fatality rate for all U. S. industries during this same period was 5.1 per 100,000 full-time workers. Figure 1-2 compares the fatal injury rates by year for the four major industry sectors of mining to the fatality rate for all industries combined. Figure 1-3 compares age-specific fatality rates in the mining industry to those seen for U. S. industry as a whole. Fatality rates for all industries combined were lowest for young workers and steadily increased in relation to workers' ages. In the mining industry, fatality rates by age group show a U-shaped curve. Young workers under 20 years of age had the highest injury rate (54.6 per 100,000), followed by workers aged 20-24 (50.8 per 100,000) and workers over age 65 (37.7 per 100,000). Table 1-1 shows the distribution of injuries by type of injury event. The mining industry, in comparison with all industries, had a considerably larger proportion of fatalities classified as caught in or crushed by collapsing materials (9.1% and 1.9%, respectively) and fires and explosions (10.0% and 3.1%, respectively). Transportation events comprised the largest proportion of fatal injuries in both the mining industry and all industries. Within the mining industry only, transportation accounted for the largest proportion of fatalities in all mining sectors except coal. A more detailed examination of the transportation events within the mining industry showed that highway incidents (50.5%) were the most common, followed by nonhighway incidents (22.2%), pedestrian incidents (10.6%), and those incurred during rail, water, and air transport (15.7%). Incidents involving caught in or crushed by collapsing materials comprised a higher percentage of injuries in the coal and metal sectors, while fall-from-height incidents were more frequent in the oil and gas sector. The classification system used in CFOI for type of injury event is not compatible with any variables contained in the MSHA data; therefore, direct comparisons are not attempted. [ ]

Jan 5, 2000

By E. P. Youngman

At the time of the preparation of the monograph upon the mining legisla- tion of Newfoundland, by the Imperial Institute of London, the existing local statutory law (as distinct from case laws and the applicable English acts) con- sisted of the following legislation: 1. Chapter 129 of the consolidated statutes, entitled "Of Crown Lands, Timber, Mines and Minerals," as amended by the Crown lands act, 1928. 2. Chapters 131 and 132 of the consolidated statutes (acts relating to mines regulation and rewards for discovery of minerals, respectively). 3. Crown lands act, 1918, as amended by the crown lands (amendment) act, 1921. 4. The Labrador Act, 1927. 5. The Crown royalties act, 1927. 6. Crown lands act, 1928, together with rules and regulations issued thereunder.

Oct 1, 1932

By Arthur Matzick

The oil shale from the Mahogany zone of the Green River formation in northwestern Colorado has the greatest potential in the United States for early utilization. A large reserve of adequately rich shale is available to support a sizable industry, and crushing of tremendous tonnages will be required if conventional processing methods are used. This report presents Bureau of Mines data on crushing experiments, physical properties, and related information for Colorado oil shale. Among the properties important to crushing are slab-forming tendency, resilience, slippery character of the richer grades, and heterogeneous nature of an average charge of Colorado oil shale.

Jan 1, 1960

By Thomas J. Witzig

This Bureau of Mines report is a background study of the International Tin Agreement. Attempts at stabilizing the tin market prior to the agreement are detailed, as well as the conditions and negotiations that set up the agreement. Details of the five consecutive 5-year agreements beginning in 1956 are presented, with emphasis on membership and the agreements' primary tools: the buffer stock and export controls, Attention is focused throughout on the United States activities during the period, especially with regard to its strategic stockpile, and its involvement with the agreement culminating in its membership, for the first time, in the fifth agreement beginning in 1976. Considerations leading to the U.S. decision to join are detailed, and U.S. activities in the negotiations for the sixth agreement are presented. The status and outlook for the agreement are discussed, and evaluations of the effectiveness of the agreement and its components are reviewed.

Jan 1, 1981