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By Wesley Hermanson

Canopies were designed, fabricated, installed, and demonstrated for mining machinery in 3-foot coal seams. A Wilcox PJ20 Auger miner, a Wilcox Bolter, a bee Norse 245 miner, and an Elkhorn Scoop AR3 modified to AR4 were fitted with canopies. The Wilcox Bolter canopy was hydraulically adjustable in height; the rest were manually pin adjustable. The machine operators' comments were adverse in each case. Restriction of visibility and body constriction into unaccustowed and tiring attitude were major objections, causing increased hazards and fatigue. Recommendations are made that roll bar protection be furnished in place of canopies for 3-foot seams to provide partial protection by deflecting and supporting roof falls but not covering the head of the operator. In this way, the effect on visibility would be minimized and fatigue from body restriction would not be increased.

Jan 1, 1976

By N. F. Le] [Jaune

[ ]

Jan 1, 1923

By A. E. Raddatz

The Federal Bureau of Mines, as part of its goal to minimize undesirable environmental impacts associated with mineral processing, has investigated a soda-smelting technique for processing ilmenite into pig iron and a titanium slag that is suitable for a feed to a sulfate-process titania pigment plant. By this procedure, the generation of ferrous sulfate waste and its associated disposal problem is obviated. Molten titania slag was quenched, water leached, and filtered to yield a sodium titanate intermediate product containing about 70 wt-pct Ti02, 1 wt-pct Fe, and 20 wt-pct Na20. This intermediate product, high-soda titanate (HST), was mixed with H2S04, calcined, quenched, and water leached to produce a low-soda titanate (LST) product that contained only 2 wt-pct Na20. Both the HST and LST were evaluated as feed materials for preparing titania by the sulfate process. About 95 pct of the Ti02 was extracted from HST and LST by digestion in concentrated or 50-wt-pct-H2S204 solutions. About 95 pct of the solubilized Ti02 was subsequently recovered from the titanyl sulfate solutions by hydrolysis. Barren solutions from hydrolysis, containing about 26-wt-pct H2S04, were upgraded by vacuum-thermal evaporation or electrodialysis. The regenerated acid solutions were used to digest additional HST and LST.

Jan 1, 1979

By D. L. Bickel

This report presents a Bureau of Mines study intended to determine if horizontal stress trends exist and if the stresses can be projected for improved mine design in a selected coalfield. The horizontal stresses were determined in three mines in the Yampa Coalfield and one mine in the adjacent Danforth Hills Coalfield of northwestern Colorado. Stresses were determined from stress-relief measurements using a three-component borehole deformation gauge and overcoring techniques developed by the Bureau. A least-squares method of calculating the average rock stress components in the horizontal plane was performed. Physical properties of the rock from the test sites are also included. For the Yampa Coalfield, the maximum horizontal compressive stress in the floor ranged from 363 to 1,956 psi, and the maximum horizontal compressive stress in the roof ranged from 235 to 875 psi. For the Dan-forth Hills Coalfield, the maximum horizontal compressive stress in the floor ranged from 360 to 1,494 psi, and the maximum horizontal compres-sive stress in the roof was 1,033 psi. Results indicated a trend of low horizontal stresses in the Yampa Coalfield that have not impacted ground control conditions in mines less than 1,000 ft deep.

Jan 1, 1988

By Edward E. Johnson

The Bureau of Mines publishes in its ?Minerals Yearbook? a series of indexes on the domestic minerals industry. Among these are the index of physical volume of mineral production, indexes of stocks, and indexes of average unit mine value and implicit unit value, This report describes the material coverage of these indexes and the methods used in their construction. Detailed descriptions are given for several other mineral-oriented indexes regularly published by other government agencies. These descriptions give the index user a better understanding of what each index purports to measure and aids him in selecting the most appropriate index for his purpose.

Jan 1, 1965

By Edward E. Johnson

The Bureau of 'Mines publishes in its ?Minerals Yearbook? a series of indexes on the domestic minerals industry. Among these are the index of physical volume of mineral production, indexes of stocks, and indexes of average unit mine value and implicit unit value, This report describes the material coverage of these indexes and the methods used in their construction. Detailed descriptions are given for several other mineral-oriented indexes regularly published by other government agencies. These descriptions give the index user a better understanding of what each index purports to measure and aids him in selecting the most appropriate index for his purpose.

Jan 1, 1965

By James Westfield

Following is a resume of activities of the Division of Coal-Mine Inspection that have had a favorable effect on health, safety, and the reduction o1 injuries at coal mines: 1. The Federal Mine Safety Code for Bituminous Coal and Lignite Mines of the United States was issued originally by the Director of the Bureau of Mines July 24, 1946, after consultation with management and labor representatives of the coal-mining industry. The code has been used by Federal coal-mine inspectors while inspecting bituminous coal and lignite mines as a basis for determining the existence of unhealthful and unsafe conditions and practices in these mines. A revised code was issued by the Secretary of the Interior October 8, 1953, after further consultations with representatives of management and mine workers and was incorporated by reference in the 1952 and subsequent bituminous coal wage agreements. The agreement of May 29, 1946, between the Secretary of the Interior, acting as Coal Mines Administrator under authority of Executive Order 9728, and the United Mine Workers of America, covering bitumi¬nous coal and lignite mines in Government possession, charged Federal coal-mine inspectors with the responsibility of making periodic investigations of the mines and reporting to the Coal Mines Administrator any violations of the Federal Mine Safety Code. Federal coal-mine inspectors also had temporary authority to close mines found to be imminently dangerous, but such authority (under Executive Order 9728) was removed June 30, 1947, when Government control of the mines was terminated.

Jan 1, 1959

By W. A. Stickney

The Bureau of Mines conducted beneficiation and smelting studies on siliceous offgrade manganese samples to indicate effective methods of manufacturing silicomanganese from materials that cannot be economically beneficiated to meet General Services Administration (GSA) specifications for stockpiling. Laboratory and pilot-plant flotation tests were conducted on 2 samples, 1 from the waste-tailings dump of the Domestic Manganese & Development Co , Butte, Mont., and the other from the Nettie mine in the Butte-Philipsburg area. Smelting tests were made on the combined concentrates from the pilot-plant flotation tests and on part of the tailings sample The flotation scheme found to be adequate in laboratory tests and later in the pilot-plant tests consisted of flotation by a fuel oil-tall oil emulsion in an acid circuit (pH )-1-.8 to 5.0). The oil-emulsion reagent flocculated the manganese minerals and selectively floated them from the siliceous gangue, In the pilot-plant flotation test on Butte-mill tailings 90.1 percent of the manganese was recovered in a concentrate that analyzed 32.6 percent Mn, 4.8 percent Fe and 28.1 percent Si02. In the test on Nettie mine ore 90.8 percent of the manganese was recovered in a concentrate that analyzed 36 6 percent Mn, 5.5 percent Fe, and 26-4 percent Si02.

Jan 1, 1956

In presenting this list of permissible explosives and blasting devices, the Bureau of Mines desires to call attention to pages 19 and 24 outlining, the conditions in use under which, and only under which, the explosive or blasting device is permissible. In view of a recent publication recounting trade practice favoring the use of a blasting device without stemming, particular emphasis is placed upon condition 4 on page 19 and condition 2 on page 24. An explosive or a blasting device enumerated in the permissible lists of this Bureau is not permissible in use unless it is properly confined with clay or other incombustible stemming.

Jan 1, 1940

In presenting this list of permissible explosives and blasting devices, the Bureau of Mines desires to call attention to pages 19 and 24 outlining, the conditions in use under which, and only under which, the explosive or blasting device is permissible. In view of a recent publication recounting trade practice favoring the use of a blasting device without stemming, particular emphasis is placed upon condition 4 on page 19 and condition 2 on page 24. An explosive or a blasting device enumerated in the permissible lists of this Bureau is not permissible in use unless it is properly confined with clay or other incombustible stemming.

Jan 1, 1940

By Howard J. Pincus

The purpose of the study is to investigate the effects of fracture filling and associated alteration on the mechanical behavior of rocks. Results are presented for specimens from the Climax and Henderson mines in Colorado and the San Manuel mine in Arizona. The rock types studied from each location are from 1) Climax, medium-grained - granite, fine-grained granite, granite porphyry, schist, and gneiss; 2. Henderson, rhyolite porphyry; 3. San Manuel, quartz monzonite and quartz monzonite porphyry. A description of the rocks was made including: color, texture, mineral composition, composition and fabric of fracture fillings, density and porosity. Unconfined and triaxial compression tests were run on the Climax and San Manuel specimens. Sonic relocities were measured during the compression tests; Shore sceleroscope hardness was measured before the compression tests. Tentative conclusions are that some relation appears to exist between compressive strength and the following properties and features for all the specimens: dynamic Young's modulus, sonic velocity, density, rock composition, and composition and fabric of fracture fillings - veinlets. There appears to be some relation between compressive strength and Shore scleroscope hardness and porosity for quartz monzonite (San Manuel). A relation appears to exist between compressive strength and texture for schist and between com¬pressive strength and extent of failure on fracture fillings for fine-grained granite, schist, and gneiss (Climax). We plan to perform additional analyses of data collected so far and data yet to be collected in the next few months, with emphasis placed on devising a practical index of alter¬ation that can be used in the field. Limitations on interpretations arise from such factors as heterogeneity of the rocks studied, the small range of confining pressures used, and other factors presented in the text.

Jan 1, 1973

By Thomas J. Peters

The Lime Creek study area lies 100 air km east of Boise, and 70 air km northeast of Mountain Home, Idaho. The eastern boundary of the 28,000-hectare, east-west-elongate study area lies 0.2 km west of the 3,077-m-high Smoky Dome. The area is mainly underlain by Cretaceous granitoid rocks of the Idaho batholith. No mineral resources were identified, but two mines and one prospect were found in the study area. At the President and the Last Chance mines, in the southwest corner of the study area, gold mineralization occurs along steeply dipping east-northeast-trending faults and associated quartz veins, and within adjacent Cretaceous granitic rock. The mineralized material is not rich enough to mine underground, and near surface, open-pit-mineable deposit areas could not be identified. The third prospect, the Ventura, is within altered pink granite of probable Tertiary age, but metal concentrations are very low. Geothermal activity was not observed within the study area, but hot springs do occur in the Vicinity. Bedrock observed is only suitable for the most basic high bulk and low end value applications, such as crushed aggregate. Numerous sources for crushed stone occur closer to markets. Alluvial concentrate (placer) samples did not contain free gold, and no substantial alluvial bars were seen; deposits were too small to contain resources.

Jan 1, 1993

By B. J. Moore

This publication contains routine analyses and related source data for 547 natural gas samples from 22 States and three foreign countries. Of this total, 340 samples were collected during calendar year 1967. The remaining 207 analyses are of samples collected during previous years, but releases granting, permission to publish the results were not received until 1967. All samples were collected as a part of a continuous survey of the free world for occurrences of helium in natural gas. The Bureau of Mines has conducted this survey in the United States since 1917, and in 1965 it was expanded to include foreign gasfields. 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 516.4 Nine previous publications have been made to present results of 7,618 gas analyses made by the Bureau of Mines Helium Activity prior to 1967. The first three, Bulletins 486,5 576,6 and 6177 contain analyses and related source data on 5,218 gas samples collected from 1917 through 1960. The other six

Jan 1, 1968

By Thomas G. Chapman

The four major steps in the production of marketable copper are mining, concentrating, smelting, and refining. In a few cases, however, leaching takes the place of concentrating, smelting, and refining, and in others ores are smelted without being concentrated. Copper ores have been milled since the early days of mining in the United States. Except in the Michigan district, most copper ores went direct to the smelter until the so-called porphyry mines were developed. At present, although considerable leaching and direct-smelting ores are produced, the bulk of the copper ore mined is concentrated. Improved methods of concentration have kept pace with the increased tonnages of ores milled.

Jan 1, 1936

By Lars Skogsberg

Work with hand-held power tools can be found in most industries all over the world. This type of work exposes the operators to different kind of loads like gripping-forces, feed-forces, exposure to vibration and noise, holding hot or cold surfaces and the exposure to dust. Designing a power tool with good ergonomics is a matter of finding the best compromise. As a simple example, increasing the mass is not acceptable because it will increase the forces needed to handle the tool. At the same time increased mass will in most cases reduce the vibrations. Vibration disorders related to the use of hand-held power tools has been known and reported since long. It is therefore essential that low vibrating tools are developed and used. The new vibration regulations in Europe, based on the Physical Agents (Vibration) Directive, have put increased focus on the vibration control in industry. Forces acting on the tool cause vibration Tools for industrial use must be of very robust design to withstand the very hard use they are exposed to. Industrial tools are therefore normally designed with the main parts made of metal. From a vibration point of view this means that most tools can be regarded as rigid bodies, especially because the dominating frequency normally is equal to the rotational frequency of the tool spindle or the blow frequency for a percussive tool. These frequencies are with few exceptions below 200 Hz. Handles however can not always be regarded as rigidly connected to the tool. There are several examples of weak suspensions designed to reduce vibration transmitted to the hands of the operator. There are also examples of designs where the handles just happened to be non-rigidly connected and in some cases even in resonance within the frequency region of interest. Oscillating forces act on the tool and the result is vibration. Design principals In all cases forces are the source of vibration. This leads to the three basic principles to control vibration: • Control the magnitude of the vibrating forces. Examples are the balancing unit on a grinder or the differential piston in a chipping hammer. • Make the tool less sensitive to the vibrating forces. Examples can be when the mass of the guard on a grinder is rigidly connected to the tool to increase the inertia of the tool. • Isolate the vibrations in the tool from the grip surfaces. Examples are vibration-dampening handles on grinders or pavement breakers, the air-spring behind the blow-mechanism in a riveting hammer or the mass spring system in a chipping hammer.

Jan 6, 2006

By Pete G. Kovalchik, Lynn A. Alcorn, Rudy J. Matetic, Adam K. Smith

Over-exposure to noise remains a widespread, serious health hazard in the U.S. mining industries despite 25 years of regulation. Most other categories of illnesses and injuries associated with mining have improved, with the exception of hearing loss. Mine Safety and Health Administration (MSHA) coal noise sample data collected from 2000 to 2002 show that 65% of the equipment whose operators exceeded 100% noise dosage is comprised of seven different types of machines. The continuous mining machine is first among all the equipment with 35% of the noise overexposures. The ational Institute for Occupational Safety and Health (NIOSH) is conducting research to reduce excessive exposure for operators of continuous mining machines and preventing additional cases of oise Induced Hearing Loss (NIHL) by developing low-cost retrofit noise controls for mining equipment. This paper describes a noise control for reducing the noise overexposures of continuous mining machine operators. Underground results show a 26.4% and 27.4% noise exposure reduction for the continuous mining machine operator. This research is providing the mining community with an additional noise control to be utilized on continuous mining machines, therefore reducing operator noise overexposure. Utilizing this newly developed noise control, along with previously proven controls for the continuous mining machine chain conveyor, will provide operators of these machines an opportunity to be within the MS HA-Permissible Exposure Limit (MSHA-PEL).

By K. R. Dorman

To develop the potential of precast concrete sets as a support medium in underground mines, a three-piece precast concrete drift set was designed for a small opening and tested to destruction in an underground straining frame. Thirty-six tests were made with three sizes of members using three different loading conditions. In addition, 14 members were tested individually in the laboratory. Test results are compared with theoretical calculations. A cost comparison shows the use of concrete sets would be advantageous where conventional wooden timber requires excessive replacement.

Jan 1, 1968

By R. H. Church

As part of the research effort of investigating the effects of microwave energy upon the chemical and physical properties of different minerals and ores, the Bureau of Mines has conducted basic research into identifying those properties of minerals that are affected by microwave energy, namely, the dielectric constant and loss tangent. These properties were determined utilizing the theory of microwave propagation in a coaxial waveguide filled with a dielectric material and measuring the input impedance with an RF impedance analyzer that operates from 1 MHz to 1 GHz. By knowing the microwave frequency and filling the waveguide with a powdered mineral, the dielectric properties of the mineral sample were determined. From these dielectric properties, theoretical microwave heating characteristics of each mineral could be calculated. These same mineral samples were then irradiated by a 915 MHz 30 kW variable power microwave oven and dielectric heating studies were performed. A comparison of the theoretical heating characteristics and the results from actual dielectric heating studies was conducted to evaluate the dielectric property measurements on each mineral. This report presents the results of the Bureau's research in identifying the dielectric properties of low-loss minerals according to the mineralogical classification scheme along with their irradiation studies. Though far from complete, this study represents some of the more frequently encountered low-loss minerals.

Jan 1, 1988

Research 86 highlights significant studies conducted during the past fiscal year at Bureau facilities and offices. Readers who want more information about the projects and studies summarized here can contact the researchers whose names and locations appear with each summary. General information on Bureau of Mines programs is available from the Office of Technical Information 2401 E Street, NW., Washington, DC 20241. A listing of principal officials, a location map of field facilities, and a selected bibliography of publications and patents issued on Bureau developments during the past 3 years are provided.

Jan 1, 1986

By Piyush K. Dutta

This report describes the design, development and manufacture of production stoper drills and results of their field tests, it is shown that underground stoper drill noise level can be reduced from 118 dBA to below 100 dBA by using these pneumatic drills. The design concept of these drills is a radical departure from the standard valved rifle bar type drill machine design to a drill featuring a valveless independent rotation system, use of an integral muffler and a shroud tube. Six drills were manufactured in a standard commercial drill manufacturing setup and organization. The design and production technology proved that commercially viable quiet drills can be made available for mine use.

Jan 1, 1983