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By Charles L. Kimbell

For the world mineral industry as a whole, the year 1981 was a period of continuation and, in some instances, an acceleration of negative trends extending back into 1980. Most available statistical data reflected stagnation or downturns in activity. Levels of production, trade, and consumption declined for a substantial number of leading mineral commodities, including, most notably, steel and petroleum. Investment, if not lower than in 1980, was evidently increasing at a more modest rate. Prices for major mineral commodities were generally lower, at least in terms of constant dollars, and in some cases even in terms of current dollars. Prospects of a major reversal of these patterns seemed dim. The mineral industry, however, was far from alone in this general downturn; most other elements of the national economies of the world's nations fared little better. General conditions of inflation, recession, and reduced industrial product consumption were reflected in most other sectors of the total economy. International political events continued to influence mineral output and flow but had less influence on overall levels of activities than on the geographic distribution of these activities. The Iran-Iraq war certainly played a role in reducing mineral industry activities in those nations, but the commodity most affected, petroleum, was available from other sources in sufficient quantity that, in the face of reduced demand, a substantial surplus developed.

Jan 1, 1983

By John R. Bartels

Remote operation of continuous mining machines has enhanced the health and safety of underground miners in many respects; however, numerous fatal and non-fatal continuous miner struck-by accidents have occurred. In an effort to prevent these injuries, NIOSH researchers at Pittsburgh Research Laboratory studied the workplace relationships between continuous miner operators and various tramming tasks of the equipment using motion capture data, operator response times, and field of view data to evaluate the factors influencing operator-machine struck-by events (contact with a solid object) in a virtual mine environment. It is not feasible (nor ethical) to use human subjects to directly evaluate factors that precipitate such injuries. However, use of motion analysis data and digital human models can facilitate analysis of struck-by accident risk by allowing investigators to manipulate factors that influence injury. Factors included in this study included machine speed, direction of escape, the direction the operator was facing relative to the machine, work posture, distance from machine, and operator anthropometry. Close proximity to the machine, high machine tramming speeds, a right-facing orientation and operator positioning near the tail all resulted in high risk of being struck.

Jan 1, 2008

By John E. Pahlman

An increasing number of gold and silver mining operations are employing cyanide solutions to effectively dissolve silver and gold from finely disseminated ores. Many of these operations use small, packaged processing systems like the State of Maine filter system, which employs zinc precipitation of gold and silver. Solution-clarifying filters in these systems become blinded with calcium carbonate (CaC03) scale and require frequent (every 2 to 10 days) dismantling of the filter units for acid cleaning, This is a hazardous operation as it is not compatible with the alkaline cyanide leach solutions and may result in the evolution of toxic hydrogen cyanide (HCN) gas during cleaning and during any accidental acid spill. The Bureau of Nines has investigated an alternative, nonacidic method of cleaning blinded State of Maine filters that employs ethylene- diamine-tetraacetic-acid (EDTA) type chelating agents to dissolve the scale. In situ cleaning of a 150-st/d State of Maine filters with EDTA- type chelating agents was successfully demonstrated. Greater than 90 pct of the CaC03 scale was removed in about 10 min with circulation of 31 L of 2.5-pct-EDTA solution through the filter unit. The EDTA cleaning method not only eliminates the cyanide hazard in filter cleaning but is advantageous from the standpoint of operating costs and productivity.

Jan 1, 1986

By Edwin B. Cook

This report presents the results of calculations of the equilibrium composition of the products of combustion with air of six different mixtures of octane CgH18, plus PbEt4 and halogen-bearing scavengers at three air-fuel ratios, at pressures of 5 and 30 atm., and at temperatures of 350°, 1,000°, 1,800°, and 2,000° K. The air-fuel weight ratio has the values 12, 15:12, and 18. The concentration of PbEt4, M, in milliliters per gallon of iso-octane, has the value 1 or 3. The word "case" is used to designate the halogen concentration. Three cases have been considered [ ]

Jan 1, 1953

By Ren G. Dong, Dan E. Welcome

Instrumented handles or dynamometers are widely used to measure hand forces and/or the biodynamic response of hand-arm system. To study hand-transmitted vibration exposure, six generations of instrument handles were constructed or initially developed by researchers in ECTB/HELD/NIOSH. This presentation provided a summary of these handles. Their basic characteristics, limitations, and usefulness are described, which may help their appropriate applications and further improvements. Six Designs of Instrumented Handles Handle 1: The conceptual design is recommended in ISO 10819 (1996)1 for glove test. The grip force is measured by detecting bending strains on a measuring beam in the handle. A special handle fixture was designed to connect the handle to a shaker. Except the screws, the handle and fixture were made from aluminum. Handle 2: The design is based on the principle of shear strain measurement.2-3 Both grip and push forces can be measured simultaneously using this handle. This handle was directly designed for a simulated vibrating tool. Handle 3: This design is basically composed of a handle base, a measuring cap, and two charge-based sensors (Kistler 9212) sandwiched between the base and cap. The handle was also made from aluminum. The fixture for Handle 1 was also used with this handle. This generation of handle has three different handle diameters (30, 40, and 50mm).4 Handle 4: This design is an improvement from Handle 3. The handle fixture was totally redesigned and it was much stiffer than the previous one. The aluminum measuring cap was replaced with a magnesium cap. Handle 5: The basic structure of this handle is the same as that for Handle 3. However, the piezoelectric sensors were replaced with two strain gage based sensors (Interface SML-50). Handle 6: This handle includes two measuring caps, four piezoelectric sensors, and a handle centre base. The handle fixture was the same as that with Handle 4. Methods for Handle Examinations The static and dynamic characterizations were performed using the methods reported by Dong et al.5-6 Results and Discussion Handle 1: The static force measurement depended on the hand grip location on the handle. Its natural frequency was less than 200 Hz.5,6 Because the transmissibility of gloves may not vary significantly with the applied grip force, this handle may be acceptable for glove test. However, the force measurements with this handle may not be reliable. Handle 2: The static force measured with this handle was insensitive to the hand acting location. However, when the handle was vibrating, the force signals could be totally distorted. For this reason, it was not used for vibration studies.

Jan 6, 2006

By A. Salmoni, E. K. Gillin, T. Eger, A. Cann, P. Vi, M. Hunt

Kittusamy (Kittusamy & Buchholz, 2004) state that there have been few studies conducted to assess exposure to whole-body vibration (WBV) in the construction industry. They suggest that there is very little reliable data from the construction industry that characterizes exposure levels to various hazards including WBV or the health outcomes from such exposure and that there is a need for more exposure data. In a recent exploratory study of heavy construction equipment Cann (Cann, Salmoni, Vi, & Eger, 2003) looked at vibration levels for 14 different types of construction equipment. Eight of the 14 pieces of equipment tested exposed operators to levels of WBV that exceeded the recommended limits for an 8-hour period when comparing the measured VDV to the ISO 2631-1 standards. The purpose of the present research was not only to test a larger number of scrapers but also to investigate scraper operator exposure to whole body vibration (WBV) separately for each task. Methods 33 scrapers were evaluated for WBV in a variety of residential and road construction projects. Testing equipment consisted of triaxial accelerometers that allowed vibration data collection in all three orthogonal axes, with the x-axis positioned to measure vibration in the anterior-posterior direction, the y-axis in the medial-lateral direction, and the z-axis in the vertical direction. Root mean square accelerations (aRMS), vibration dose value (VDV), crest factor, and maximum transient vibration values (MTVV) were derived from this software and exported to an Excel™ spreadsheet for later data analysis. Test sessions for each piece of equipment lasted for approximately 20 minutes until at least three work cycles had been completed. Tasks included: idling while waiting for a bulldozer to push the scraper through the scraping phase, scraping, traveling loaded with dirt, dumping and traveling empty. Results Task breakdown by time reveals 25% of the work cycle was spent traveling fully loaded with dirt, 19% dumping, 21% traveling unloaded, 17% idling and 18% scraping. Calculation of aRMS vector sums gave values of 2.55 m/s2 during loaded transport, 2.46 m/s2 during dumping, 2.31 m/s2 during unloaded travel, 0.55 m/s2 during idling and 1.46 m/s2 during scraping (see Table 1). The highest acceleration values recorded were found in the z-axis during fully loaded transport reaching an average aRMS over three work cycles of 2.55 m/s2.

Jan 6, 2006

By W. H. Young

PRODUCTION of bituminous coal and lignite increased substantially in 1964. There were upward trends also in consumption, average value, exports, mechanization, and productivity. However, a significant decline in employment continued. Production.-The output of bituminous coal and lignite in the United States in 1964-487 million tons-was 6 percent greater than the 459 million tons produced in 1963. The gain was attributed largely to expanded consumption by the electric utilities, greater use at coke ovens, and an increase in exports.

Jan 1, 1965

By C. F. Ellis

Interest in the composition of automobile exhaust gases has been greatly accelerated by recent studies that have indicated that these gases contribute to smog formation in urban areas. Several analytical methods have been published for the analysis of the hydrocarbons in the exhaust gases, but similar information has not been published on the analysis of the oxygenated compounds. This report presents procedures for chemical analyses of certain oxygenated compounds, procedures for sampling the exhaust gases for these analyses, and the analytical results of some experimental work in which these procedures were used. A stationary 1956 model, 170 horsepower, V-8, dynamometer-mounted engine, operated to simulate vehicular cruise conditions, was used for the study. Exhaust gases produced from a regular-grade Midcontinent gasoline during 15-40- , and 60-mile-per-hour cruise operations were analyzed by chemical methods for formaldehyde, total aldehydes, total carbonyls, total alcohols, carbon associated with the oxygenated compounds, and the oxides of nitrogen. Experimental results indicate: 1. The range of concentrations of the total of the functional groups of oxygenated compounds, expressed as moles per million moles of water-free exhaust gases, is about 90-100; the concentrations increase with engine speed. 2. Aldehydes comprise about 80-90 mole- percent of the total of the oxygenated groups, and formaldehyde accounts for about 50 mole-percent of the total aldehydes. 3. The order of magnitude of the concentration of the carbonyls is the same as that for the aldehydes, indicating that ketones are not a major group. A colorimetric test indicates that methyl ketones Constitute about 2 mole-percent of the oxygenated compounds.

Jan 1, 1961

By P. M. Gruzensky

A survey of the literature has been made covering the extraction of bismuth from raw materials, its separation from lead, and its subsequent refining. The use of aqueous, nonaqueous, and fused electrolytes in electrolytic refining is reviewed. This literature survey has been prepared preliminary to some proposed investigations concerning the electrometallurgy of bismuth, and, although an effort has been made to cover a majority of the applicable references, a critical review was not attempted and no assertion is made that this manuscript is exhaustive in nature. Titles of publications in parenthesis are translations from the language in which the reference was originally published.

Jan 1, 1954

In September 1985, the Chairman of the Transportation, Aviation and Materials Subcommittee of the House of Representatives requested that the Director of the Bureau of Mines address the issue of South Africa and critical materials dependency in testimony before the Subcommittee. Subsequent to the testimony, the Bureau has prepared a technical report focusing on the importance of South Africa and, in some cases, its neighboring countries as suppliers of six key materials. The report includes a qualitative analysis which examines the supply shortfall resulting from a potential disruption, options that are available for mitigating the impact, and their likely effectiveness, and quantitative analyses which estimate the economic impacts in the chromium and manganese markets resulting from peacetime disruption scenarios specified by the Subcommittee Chairman. The concluding section treats the role and capabilities of the Bureau of Mines in dealing with mineral supply disruptions.

Jan 1, 1986

By Charles L. Kimbell

The year 1986 was not a good year for the world's mineral industry from several viewpoints. Levels of production, both of crude minerals and processed forms, registered declines in the cases of a greater number of commodities than the number that recorded increases. The overall value of world crude mineral production was estimated to have increased, but only very slightly in terms of constant dollars to nearly $997 billion. Although there were modest increases in the consumption of all major fuels and most major metals, the latter at least apparently resulted more from drawdowns of inventories than from increased production (fuel consumption increases did come from higher output levels), and consumption of most major fertilizer and chemical commodities (nitrogen, phosphate, and sulfur) were at lower levels than those in 1985. Prices for a number of mineral commodities declined, headed by the very substantial drop in world crude petroleum prices, but also including downturns for a number of metals and industrial minerals as well. There was insufficient information to reliably fix the level of the dollar value of world trade in minerals, for while output was up in the case of some large-volume materials such as iron ore, coal, and crude and refined petroleum, suggesting that the volume of trade in physical units may have increased, declining prices may well have offset quantitative gains.

Jan 1, 1988

By Richard Stayner

Suspended seats perform two functions: Reduce effect of occasional large bumps; Reduce more continuous vibration at a lower level. The former needs high damping. The latter needs low damping. For most mobile work machines the inevitable compromise is generally better than a simple cushion seat, because that amplifies vibration at around 4 Hz which is a sensitive frequency for human vertical WBV. Why have standard tests for seat suspensions? • Seat suspensions are non-linear so any measure of performance depends on operating conditions. For comparison these need to be defined. • Seat manufacturers need benchmarks for product development; • Machine makers choose dynamic characteristics appropriate to their products; • Occupational health specialists wish to control operator exposure to Standard tests should be representative, repeatable and reproducible. These requirements are reviewed in relation to the history of seat test standards and the current position. Current position and history The current position is that we have standard tests for seats for agricultural tractors, earthmoving machinery, industrial (fork-lift) trucks. These tests comprise measurement of vibration transmission and of the rate of damping. Current standards developed as the technology developed, starting around 1960: 1. Test on machine driven over standard surface1. 2. Test on shaker reproducing standard surface. 3. Shaker input replaced by representative spectrum2. 4. Human subject replaced by dynamic dummy. (Not yet settled). Are standard tests representative? The development process has gradually moved seat tests further from reality. 4 hr samples of work exposure suggest that seats do not on average provide large reductions of vertical WBV3. For specific magnitudes of vibration they can work well. For low vibration, performance is reduced by friction and for severe vibration by length of travel. Recent work has led to a new test to quantify how a suspension controls over-travel 9.

Jan 6, 2006

By McMillan W. D.

Vermiculite is the name of a group of micaceous minerals characterized by their property of exfoliating when heated and thereby increasing many times their original volume. The resulting product has excellent heat-and sound-insulating properties, is used as a lightweight aggregate, and has numerous other industrial applications. Deposits of vermiculite occur in areas of pre-Cambrian rocks of the Llano uplift of central Texas, particularly in Burnet and Llano Counties. Because of the growing economic importance of vermiculite products, the Bureau of Mines undertook a detailed investigation of several deposits in Llano County. This investigation was completed in February 1947. The work comprised topographic surveys of five deposits, drilling with a 4-1/4 inch Parmanco power auger drill, and laboratory evaluation of samples. 342 drill holes, aggregating 4,905.5 feet, were completed, and 377 samples were taken. Laboratory evaluation of the vermiculite comprised expansion tests on both crude and beneficiated samples. The products obtained were compared with commercial-grade vermiculite from Montana.

Jan 1, 1949

By Henry M. Harris

Low-carbon shales from 65 deposits and 11 sources of coal-mine waste in western Oregon and Washington were tested in a rotary kiln for their suitability as raw material for expanded aggregate. Shales from 41 sources bloated enough to produce crushed, expanded aggregates, weighing less than 65 pounds per cubic foot in the preliminary tests. The samples were judged on the basis of processing qualities, physical properties, and size and uniformity of the source. Nine low-carbon shale deposits and three coal-mine waste sources were selected for more extensive bloating tests and for examination of the expanded aggregates in concrete shapes. Composite samples from these 12 sources and from 2 commercial operations, when processed for testing in concrete shapes, had bulk densities ranging from 37.S to 72.9 pounds per cubic foot. Damp-cured concrete shapes made with these aggregates had bulk densities ranging from S6 to 119 pounds per cubic foot, and all but three of the lightweight concretes had crushing strengths ranging from 3,270 to 6,810 p.s.i. Properties of the lightweight concretes were compared with those of concrete shapes made with commercial aggregates, and with sand and gravel.

Jan 1, 1962

The coal-bearing areas of Kansas cover approximately 18,800 square miles (23 percent of the state's total area). Coal in Kansas ranges from lignite to high volatile bituminous, located principally in the south-eastern part of the state. Kansas reserves are estimated to be 987,500,000 tons, approximately 0.2 percent of U.S. reserves. Coal beds generally occur in thin seams up to five feet thick. The overburden-to-coal stripping ratios in Kansas are among the highest in the nation, typically 20 to 1, with some ratios up to 35 to 1. The first commercial coal mining operation in Kansas opened in 1865 at Fort Scott in Bourbon County. As in other states, coal production in Kansas increased during the industrial revolution, and then fell as industry converted to alternative fuels. Production peaked in 1916 and 1917, with annual production of 7,250,000 tons. Coal production today is by surface mining methods. The Kansas regulatory program was approved April 14, 1982; the Abandoned Mine Land Program was approved February 1, 1982; and the emergency program authority was approved January 10,1989.

Jan 1, 1992

By Sean Gallagher

Background. There is currently little information regarding factors associated with specific modes of motion segment failure using a fatigue failure model. Methods. Thirty-six human lumbar motion segments were fatigue tested using spinal compressive and shear loads that simulated lifting a 9 kg weight in three torso flexion angles (0°, 22.5°, and 45°). Twenty-five segments failed via fatigue prior to the 10,000 cycle maximum. These specimens were visually inspected and dissected so that the mode(s) of failure could be determined. Failure modes included endplate fractures (classified into nine varieties), vertebral body fractures, and/or zygapophysial joint disruption. Logistic regression analyses were performed to determine whether certain morphometric variables, amount of motion segment flexion, disk degeneration scores, and/or loading characteristics were associated with the occurrence of specific failure modes. Findings. Results indicated that stellate endplate fractures were associated with increased posterior shear forces (P < 0.05) and less degenerated discs (P < 0.01). Fractures running laterally across the endplate were associated with motion segments having larger volumes (P < 0.01). Endplate depression was more common in smaller specimens (P < 0.01), as well as those experiencing increased posterior shear force (P < 0.05). Zygapophysial joint damage was more likely to occur in a neutral posture (P < 0.01). Interpretation. These results suggest that prediction of failure modes (e.g., specific endplate fracture patterns) may be possible (at least for older specimens) given knowledge of the spinal loads along with certain characteristics of the lumbar spine. Published by Elsevier Ltd. Keywords: Lumbar spine; Endplate fractures; Zygapophysial joints; Morphometry; Disk degeneration; Motion segments; Aging

Jan 1, 2006

By K. E. Soroka

More than 500 fires are now burning in abandoned coal waste banks and coal deposits in the United States. Once established, such fires can burn for decades, and extinguishing them by conventional methods such as surface sealing to exclude air, excavation to remove fuel, or flushing to cool the fire zone is usually difficult and always expensive. Burnout Control, a technique developed by the Bureau of Mines for the control of abandoned coal fires, involves the accelerated combustion of coal in place with total management of the heat and fumes produced. A burning waste bank or mine is placed under negative pressure relative to the atmosphere, and heat and combustion products are drawn from the combustion zone through an exhaust ventilation system. Heat produced appears as sensible heat in the exhaust, at temperatures as high as 1,0000 C (1,832° F), and could be recovered for the production of steam, hot water, process heat, or electricity. The Bureau&apos;s first held field demonstration of Burnout Control was at Calamity Hollow in Allegheny County, PA (near Pittsburgh). Calamity Hollow was the site of an underground mine in the 1900&apos;s and was surface mined in the 1940&apos;s. In the winter of 1961-62, a fire of undetermined origin was discovered in the exposed coal. In 1963, the Bureau constructed a trench barrier around the fire and a surface seal over the affected area. The fire was isolated but not completely extinguished. In 1979, when the Bureau began work on the Calamity Hollow Mine Fire Project to demonstrate controlled burnout, the fire was still smoldering on the hot side of the trench barrier. The project, which was begun in December 1979 and ended in July 1982, consisted of the design, construction, operation, and subsequent dismantling of a Burnout Control ventilation system. This report is the fifth in a five-part series that describes the Calamity Hollow Mine Fire Project. The first report, part 1, describes the design and construction of the field installation. Part 2 will present the results of a continuous 4-month burnout operation. (Because part 2 involves the analysis of a substantial body of data, it will not be published until after publication of parts 1, 3, 4, and 5.) Part 3 describes the instrumentation used to control and monitor the progress of the burnout operation. Parts 4 and 5 deal with the closeout phase of the field demonstration. Part 4 describes the procedure used to quench the fire, and this part (part 5) describes the final excavation and backfilling of the heated zones. The reports in this series document the Calamity Hollow controlled burnout demonstration which showed that (1) controlled in situ combustion is a feasible method for controlling underground fires in abandoned mines, (2) the resultant thermal exhaust output is sufficient for energy utilization, and (3) water injection-fume exhaustion is a potentially effective method for cooling large underground fire zones. Further investigations of both Burnout Control and the water-injection-fume exhaustion quenching procedure are planned.

Jan 1, 1986

By NEFE AEWFW

Changes in the 1980 quantity and value of the sales of various natural abrasives, compared with the data for 1979, were of a mixed nature. Output of garnet and special silica stone products increased in both tonnage and value during the year, while emery and tripoli-type materials production decreased in both tonnage and value. The reported quantity and value of sales of manufactured abrasive material-fused alumina and alumina-zirconia, silicon car-bidet and metallic iron and steel shot and grit-also decreased for 1980. [ ]

Jan 1, 1981

By Gerald R. Smith

Because of continuing concerns regarding the effects of cumulative quantities of materials in the environment, the Bureau of Mines has initiated a series of studies to evaluate, to the fullest extent possible, all aspects of the materials flow sequence fur selected commodities. Although tungsten and its compounds do not pose a significant health hazard to the environment, they do represent valuable resource materials to which appropriate conservation considerations must be given. The present study includes a description of recent trends in the consumption, loss, and recycling of tungsten-containing materials in the United States during the period 1974 to 1991 and an estimation of the cumulative loss of tungsten to the environment since 1910. Obsolete tungsten is recycled primarily as cemented tungsten carbide components that have been used in cutting and wear-resistant applications. The quantity recycled, as a of annual U.S. consumption of tungsten, was estimated to have increased from 10% in 1974 to 341a in 1991. An estimated 58% of the 148,000 metric tons of primary tungsten consumed since 1910 was lost to the environment through means such as dissipation, discard, and dilution.

Jan 1, 1994

To improve a miner&apos;s chances for survival in an emergency by providing an improved self-rescuer device that functions in a toxic or oxygen-deficient atmosphere. The Approach: Development of a compact, lightweight apparatus which produces oxygen by using the wearer&apos;s breath in a chemical reaction. How It Works: The device is designed to cause the user&apos;s breath, which contains water vapor and carbon dioxide, to react with potassium superoxide (K02) to produce oxygen in quantities sufficient to sustain the wearer for one hour. The system is a closed circuit and does not depend on "screening" of noxious gases. To use the device, the miner opens the top and

Jan 1, 1974