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By David C. Grant

A laboratory technique for simulating in-situ uranium mining was developed and used to determine the effects of leaching variables on permeability, uranium recovery, leach solution interaction with the ore-aquifer environment, and post-leach chemical leakage. In particular, ammonium bicarbonate, the commonly-used leach solution, was examined in great detail. Agitation leach tests were conducted to examine the effect on ammonium sorption and desorption of clay content, solution and clay ammonium levels, pH, and the type and concentration of other anions and cations in solution. Initial column tests were performed to determine the degree of ore-aquifer interaction that could be expected for various leach solutions; sulfuric acid, and ammonium, sodium, and potassium bi-carbonates. Subsequent tests examined various methods to restore the ores by lowering the post-leach chemical leakage. The restoration tests examined the use of reducing agents (e.g., ammonium bisulfite, sodium bisulfite; and sodium sulfite), ore blocking and stabilizing agents (e.g., sodium silicate, aluminum chloride, and magnesium-calcium salt).and ammonium displacement agents (e.g., aluminum chloride and lanthanum chloride-sulfate)

Jan 1, 1980

By J. F. Neill, O&apos

[The Cartersville mining district is in Bartow County, Ga., about 40 miles northwest of Atlanta. Barite, limonite, ocher, amber, hematite, and, manganese oxide ores have been produced from the strict since about 1840. In the search for a possible source of manganese ore, Bureau of Mines engineers made a preliminary study of the district from September 1950 to January 1951. During this study 139 deposits were examined, and many mineral exposures were sampled. Manganese mineralization occurs as fine oxide and concretionary pellets in residual clays, as fine oxides in umberous clay, in brown-iron deposits, and in a limited quantity in mud ponds and Jig-tailing piles. The future supply of ferrograde manganese ore from the district, using current mining and benefication methods, appears limited to the recovery of the hard manganese ores deposits. Rough estimates indicate a reserve of manganese-bearing clays of about 8,000,000 long tons. This type of deposit has been extensively exploited and the larger deposits mined out to depths of from 50 to 200 feet. The remainder of these deposits are low grade, are covered with deep layers of colluvium, or lie below the ground-water table. Any future production from this source will require systematic prospecting, improved concentration, and an increase in the price of concentrate.]

Jan 1, 1954

By Nancy Estrada, Jane Nowell, Cathy Jennings, Debra Yniguez, Carol Lavery, Kristin Harrer

Pilots of the MH-60S helicopter are exposed to continuous whole body vibration (WBV). Pilot fatigue is a growing operational concern due to the increased frequency of extended durations of missions (6-8+hours) in support of Operations Iraqi Freedom and Enduring Freedom. Endurance aspects of the currently used rotary wing seating systems were not optimized for the longer missions and wide range of pilot anthropometric measurements, which is now typical of naval aviation. The current seating systems were designed primarily to meet crashworthiness requirements, not for the wide range of pilot anthropometry or to mitigate WBV. Albeit, an issue, pilot fatigue and reduced mission effectiveness are also critical concerns. Current Hazard Reports indicated that pain in pilots’ legs and backs begin two to four hours into the flight and increase with time. Mission readiness also decreases with an increase in flight duration due to the constant distraction of pilots shifting in their seats while trying to get comfortable. Froom, et al [2] reported a dose-response relationship between the length of military helicopter flights and back discomfort. He also concluded that this pain is typically dull, over the lower back, and its prevalence and intensity are dependent on the total flight hours of exposure. Methods This study evaluated WBV produced in the pilot seating systems onboard the MH-60S. The purpose of the study was to test and compare the effectiveness of two different seat cushions, the current seat cushion versus an anti-vibration seat cushion. Both seat cushions were measured for acceleration levels averaged over five-minute intervals using a triaxial seat pad accelerometer. The recordings were completed for a 3-hour straight and level flight. A frequency analysis from 0-80 hertz (Hz) was conducted on all acceleration measurements to determine the dominant axis and frequency of the pilots’ vibration exposure. The results were then compared to the applicable Threshold Limit Values (TLVs) established by the American Conference of Governmental Industrial Hygienists (ACGIH) [1] and the International Organization for Standardization (ISO) 2631.1 [3] to determine the MH-60S pilots’ permissible exposure time for both seat cushions. Results The results of the study showed that for both seat cushions the vibration levels of the z-axis at 16 Hz had the shortest allowable exposure duration, according to the ACGIH TLVs. In the z-axis at 16 Hz, the MH-60S’s current seat cushion’s acceleration levels indicated an exposure time limit of approximately 6 hours, while the anti-vibration seat cushion’s acceleration levels pierced the 8-hour exposure time limit curve. This is shown in the graph below.

Jan 6, 2006

By Robert S. Becker

The results of a laboratory investigation of coal cutting mechanics and noise is presented. These experiments were performed using a linear cutting apparatus that operates over a broad cutting speed range. The influence of several coal cutting parameters on the noise, force, productivity, and specific energy associated with linear cuts is ascertained. Some basic theoretical aspects of coal cutting mechanics and noise generation are discussed, and the results of the laboratory experiments are used to Formulate analytical models of the coal cutting forces and noise. The analytical model For coal cutting noise is then generalized to account for the more important effects of rotary cutting. Based on the generalized model, an estimate of the sound pressure level at an operator's position is made for a typical continuous mining machine. It is concluded that by employing linear rather than rotary cuts, using deeper depths of cut, slower cutting speeds, and more efficient cutting tools, it is possible to reduce the level of coal cutting noise, as well as Provide benefits to other important areas of underground health and safety.

Jan 1, 1980

By Parry. V. F., John B. Goodman

"INTRODUCTION The Denver region coal field, covering an area of approximately 7,640 square miles, extends from the Wyoming State line to the middle of El Paso County, Colo. The coal in this region is subbituminous in rank. Much of it is used as domestic fuel. During the last decade the production of coal in this field has remained fairly constant at an average of 2,600,000 tons per year. This production has come from 50 to 60 mines, 88 to 90 percent of the production being from the section of the field north of Denver.According to the Standard Specifications for Classification of Coal by Bank of the American Society for Testing Materials 4/ the coals in this region are classified in the Subbituminous B and C group. On the as—mined basis, they contain about 22 percent moisture and average 9,600 B.t.u. per pound. They are noncoking and slack to a variable extent when exposed to the weather. This is characteristic of subbituminous coals."

Aug 1, 1939

By Terry Muldoon

In conventional noncoal, room-and-pillar mining, the cutting machine is frequently a major source of airborne dust. Water is often used for dust control. An evaluation of typically used water systems during this program showed that they reduced dust levels by 60 to 70 percent over dry cutting when at least 0.5 gpm of water was applied. These systems, however, are only marginally effective in maintaining compliance levels and the added moisture causes operational problems. During the program, three additional dust control systems were designed, fabricated, and evaluated. The first, a hollow cutter bar, was designed to capture dust in the kerf at the cutting zone. The system was only marginally effective in reducing dust levels due to its lack of control of other sources. Large quantities of material captured by the system made it operationally questionable. The second, a machine mounted exhaust system, was extremely effective in capturing virtually all the dust generated in the heading. The captured dust was ducted out of the heading and exhausted downstream in the crosscut. Exhausting the dust without scrubbing, however, creates problems for personnel working downstream of the cutting machine. Successful application would require changes to the mine ventilation system and mining sequence. The third, foam, injected foam from an onboard generator through a channel to the cutting zone at the tip of the bar. Test results showed that foam, using 1/3 to 1/2 the total fluid quantity, was equally effective when compared to the mine's current water system.

Jan 1, 1983

By James E. Bell, Clyde B. White

"INTRODUCTION The Friedensville district was one of the most important zinc-producing areas in the United States from 1859 to 1893. The ore minerals near the surface were principally calamine and smithsonite, but with depth sphalerite was found in increasing proportions. The ore bodies of the district are reported to have been in chimneys, occurring in folded and faulted beds of Beekmantown limestone of Ordovician age.The Correll was one of five mines near Friedensyille that were exten¬sively exploited. The high-grade ore shoots were mined to a depth of several hundred feet, but it is believed that inability to compete with lower-cost production elsewhere, rather than exhaustion of the ore bodies, compelled the mines to close.There is no record to indicate that any attempt was made during the period of operation to explore for additional ore in the limestone beds down the dip below the mine workings. The possibility that exploration might reveal additional ore in the limestone beds below the known ore shoots led the Bureau of Mines to diamond-drill the Correll property between September 1943 and January 1944."

Jan 1, 1948

The concept of isokinetic measurement of strength was originally related by Hislop and Perrine.(1)Characteristics of an isokinetic exertion are constant velocity throughout a predetermined range of motion. Strictly speaking, a means of speed control, and not a load in the usual sense, is applied in isokinetic exertions.(1)However, load and resistance are definitely present in this technique. In this case, the load is a result of the energy absorption process performed by the device to keep the exertion speed constant. The device prevents energy from being dissipated through acceleration in isokinetic exercise. The energy is instead converted into a resistive force, which varies in relation to the efficiency of the skeletal muscle. Since the speed of motion is held constant in isokinetic exercise, the resistance experienced during a contraction is equivalent to the force applied throughout the range of motion. For this reason, the technique of isokinetic exercise has sometimes been referred to as accommodating resistance exercise. This type of exercise allows the muscle to contract at its maximum capability a tall points throughout the range of motion. At the extremes of the range of motion of a joint, the muscle has the least mechanical advantage, and the resistance offered by the machine is correspondingly lower. Similarly, as the muscle reaches its optimal mechanical advantage, the resistance of the machine increases proportionally. It must be understood, however, that while isokinetic devices control the speed of the exertion, this does not assure a constant speed of muscle contraction. The speed of isokinetic contractions is constant during individual exertions; however, it is also possible to compare muscular performance over a wide range of isokinetic velocities. Increasing the isokinetic speed of contraction will place increasing demands on Type II muscle fibers (fast twitch and fast oxidative glycolytic). Workplace Assessment It is clear that isometric strength testing cannot substitute for dynamic strength assessment when examining highly dynamic occupational job demands. As most industrial work tasks contain a significant dynamic component, analysis of isokinetic strength capabilities appears to offer some advantage to isometric testing in this regard. However, it must be recognized that isokinetic devices are not entirely realistic compared with free dynamic lifting in which subjects may use rapid acceleration to gain a weight-lifting advantage.

Jan 1, 1998

By Charlie Vaught, Bill Wiehagen, Lynn Rethi, Pamela Kidd, Lisa Steiner, Ted Scharf, Henry Cole, Kathleen Kowalski

The most hazardous work environments share one feature in common: constant change. Many different, but constantly changing hazards are found in agriculture, construction, mining, and transport. This dynamic feature of work-place hazards varies by: (1) degree of control, (2) predictability, (3) visibility, (4) movement, and (5) degree of speed and force. In some cases the actions of the dynamic hazards are required for production to take place, and in many cases,

By William W. Adams

The quarrying and related industries of the United States made a large gain in employment (man-hours of work) in 1942 with a somewhat smaller number of men employed than in 1941. This was accomplished chiefly by increasing the number of workdays per man and also by increasing the length of the workday. In spite of the greater volume of work performed, the industry had a more favorable accident-frequency rate in 1942 than in the previous year. Accident and employment reports from operating companies showed that the industry employed 84,270 men for an average of 271 days per man in 1942, with a volume of work of almost 181 million man-hours. The average workshift comprised 7.93 hours, and the number of man-shifts worked totaled nearly 23 million. Injuries from accidents in and about the quarries and plants caused disability to 6,461 employees, 112 of whom died as a result of their injuries, including 28 employees whose lives were lost in a single disaster. The accident-frequency rate in the industry was 35.73 per million man-hours worked, comparing favorably with a rate of 40.11 for the previous year. However, the figure for 1942 included a death rate of 0.62 per million man-hours which, because of the disaster referred to, was considerably higher than the fatality rate of 0.44 for 1941. Had the disaster not occurred, the fatality rate for the industry for 1942 would have been 0.46. The major disaster in which 28 lives were lost occurred on March 26 at the Sandts Eddy quarry of the Lehigh Portland Cement Co. near Easton Pa.

Jan 1, 1944

By Jan C. Still

The Glacier Bay subarea is that part of the Juneau Mining District (JMD) within Glacier Bay National Park and Preserve (GBNP). It is the western portion of the JMD and consists of the land between the Fairweather Range crest and the Takhinsha and Chilkat Ranges crests (excluding that land east of Excursion Inlet.) Figure B-1 shows the area. It is bounded on the north by the Alaska-British Columbia International boundary, to the south by Cross Sound and Icy Strait, and contains Glacier Bay. During 1975 -1977 the Bureau conducted a detailed study of the occurrences, prospects, and deposits in GBNP (B_4).2 This work was in cooperation with the U.S. Geological Survey (USGS) under the provisions of the Wilderness Act (Public Law 88-577). As a follow up to this earlier Bureau work, limited studies were conducted, during 1985 and 1986, as part of the JMD study. This report covers the most important aspects of the earlier studies and the 1985 and 1986 studies. ACCESS The Glacier Bay area may be reached through Gustavus airport, a paved strip which is serviced by scheduled jet airliners in the summer and air taxi services year-round. The airport is connected to Bartlett Cove (GBNP headquarters) by an all-weather road. No other roads exist in the area except a skid road to the LeRoy Mine and mill in the Reid Inlet area. Much of the Glacier Bay area is accessible through the salt water inlets and fjords which are part of Glacier Bay. Cruise ships, charter boats, and fishing boats visit these inlets and fjords during the summer months. Elevations within the area range from sea level to over 15,000 feet in the rugged Fairweather Mountain Range. More remote areas are accessible by small boat, foot, or helicopter. Glacier ice is a year-round hazard to navigation in Glacier Bay, and during the winter months some of the more northerly inlets are frozen.

Jan 1, 2012

By C. B. Daellenbach

A prototype particulate size analyzer system was developed that would rapidly determine size distributions of homogeneous and two-mineral materials in the 74-micrometer (200-mesh) to 7-micrometer size range. The system sizes particles in a series of hydrocyclone elutriation steps and senses the weight of the five sized fractions by nuclear attenuation techniques. Size distribution of materials was determined from experimentally developed mathematical relationships that existed between particulate weight and the measured transmittance of gamma rays from an Americium-241 source. In the developmental phases, size distributions of three minerals (quartz, magnetite, and hematite) and a laboratory prepared two-mineral mixture of quartz and magnetite were accurately determined by the prototype system. In later stages of the investigation, semiconcentrates, an intermediate magnetic product from a taconite plant, were evaluated. Using 25-gram feed samples of this industrial material, the analyzer system was found to predict weight percentages for individual size fractions with an accuracy of ±0.85 percent or better at a 95-percent confidence level.

Jan 1, 1974

By H. John Head, Fred N. Kissell

In This Chapter [Gas reports from around the world Regulations for gassy mines in the United States Differences between metal/nonmetal mines and coal mines Monitoring for methane and taking action Diluting methane with additional ventilation Eliminating ignition sources What experienced mine operators say about methane control and Looking for methane when starting a new mine or expanding an existing mine] This chapter gives guidelines for preventing methane gas explosions during metal and nonmetal mine development and subsequent production operations.3 Emphasis is placed on recognizing the differences between coal mines, where the potential for methane hazards is relatively well understood, and metal/nonmetal mines, where methane may accumulate unexpectedly. Also, interviews with experienced mine operators add much to a complete understanding of what must be done to address methane problems in metal/nonmetal mines. METHANE GAS IN METAL/NONMETAL MINES Gas reports from around the world. The presence of methane gas in metal/nonmetal mines around the world is more common than one might imagine [Edwards and Durucan 1991]. For example: • The former Soviet republics have occurrences of methane and hydrogen in apatite, gold, and diamond ores, where solid or liquid bitumen occurs in the rock. • Scandinavian iron ore deposits include methane and other hydrocarbons in boreholes that intersect pitch and asphalt within the deposits, and methane and nitrogen in boreholes and fissures in arsenic and sulfide ores.

Jan 6, 2006

By W. P. Diamond

The direct method test was developed for general mine safety applications by the U.S. Bureau of Mines in the early 1970's to measure the gas content of coal samples obtained from the relatively shallow depths of eastern U.S. coal mines. Over time, applications for gas content data evolved which required increasingly accurate desorption values. It became evident that some of the inherent weaknesses in the original direct method test could best be addressed by abandoning the water displacement based desorbed gas volume measurements. The ideal gas law based modified direct method (MDM) and associated desorbed gas volume measurement apparatus was developed to provide the most accurate desorption values possible for rock samples obtained from any gas-bearing strata. The MDM has a number of significant advantages, including: (1) increased accuracy, especially for low gas content samples, (2) a test apparatus with an integral sampling port to facilitate the collection of uncontaminated gas samples, (3) an inherent head space effect correction in the periodic MDM desorbed gas volume calculations, (4) measurement of positive and negative desorbed gas volumes, (5) elimination of differential gas solubility effects as a source of error inherent in the water displacement methods, and (6) a compact and rugged test apparatus that along with the elimination of the ?glassware? required for the water displacement methods, facilitates its use in the field.

Jan 1, 2008

By Will B. Jamison

An ignition detection and suppression system was developed under the scope of this contract. The objective of this machine mounted system was to detect flames caused by frictional sparking from the cutting bits of a continuous mining machine and to suppress it with sufficient speed to prevent the development of an explosion, and to keep the flame from harming the machine operator.

Jan 1, 1976

By John P. McDonnell

Cable supports offer several advantages over traditional secondary support methods by enhancing stress redistribution to pillars and gob areas, minimizing or eliminating timbers and cribs that reduce ventilation, eradicating material-handling injuries related to placement of crib supports, and providing a cost-effective alternative to secondary support. The U.S. Bureau of Mines, in researching alternatives to traditional roof support methods, designed and installed high-strength cable supports to improve the stability of longwall gate road and bleeder entries in a Western U.S. coal mine. With the cooperation of industry, methods were developed to install cable supports in a tailgate and bleeder entry test area using traditional resin cartridges. Resin-grouted cable bolts were also installed and evaluated in additional longwall gate road and bleeder entry systems at the study mine. The cable-bolted areas successfully maintained roof support throughout the tailgate and bleeder entries. Cable supports replaced wood cribbing as secondary support in the bleeder entry system and minimized the use of cribbing in the longwall tailgate entries. This report describes the theory, application, and advantages of cable supports and presents mine measurements made to assess the cable performance during the retreat process of longwall mining.

Jan 1, 2010

By Leslie H. Sharp, Martin J. Gavin

"Introduction.Investigations of the oil shales of the State of Colorado were begun February 1, 1920, by the U. S. Bureau of Mines and the State of Colorado, under cooperative agreement entered into by the Bureau and the State, funds for which were provided by the State. The investigations are for the purpose of determining by large-scale Laboratory retorting tests, those conditions which will produce optimum yield of best quality products from Colorado shales. (For an outline of the work and description of the apparatus, see Gavin, Martin J., and Sharp, Leslie H., ""investigations of the Fundamentals of Oil-shale Retorting,"" Reports of Investigations, Bureau of Mines, July, 1920.)In the preliminary work which is usually required when a new material is being dealt with, certain physical and chemical constants of the shales being investigated, and their products, were determined; these data will be of much value not only to the thorough retorting tests now under way at Boulder, but to engineers who will design and construct oil-shale plants. While the figures presented in this report apply only to the shale used in the determinations, strictly speaking, the shale used was selected to represent, as well as possible, an average of the massive type of oil shale encountered in Colorado. The figures, therefore, can probably be applied with little danger of serious error to any massive Colorado oil shale which yields in the neighborhood of a barrel (42 gallons) of oil to the ton.This paper is based on a more complete article now being prepared in which experimental methods are explained in full, and complete experimental data. For the purpose of presenting the data with as delay as possible, it has been decided to anticipate the more complete article with the present report."

Aug 1, 1920

This paper has peen translated from the Russian by the United States Bureau of Mines and is issued as one of a series of circulars dealing with mining methods and costs in connection with a general study of this subject sponsored by the bureau. The paper presents some interesting features in connection with the methods employed in Russia and describes certain variations in standard methods which might conceivably be applied to a limited extent in this country.

Jan 1, 1930

By D. E. Welcome, T. W. McDowell, R. G. Dong, S. F. Wiker

Workers using vibrating hand tools have the potential for developing health problems associated with repeated forceful actions and exposures to hand-transmitted vibration. Hand-arm vibration syndrome (HAVS) and other hand-arm system disorders have been associated with such exposures.1-2 To better assess health risks, comprehensive evaluations of these exposures must include quantitative assessments of hand-tool coupling forces; unfortunately, no standardized method for quantifying hand forces exists. Handle instrumentation may be ill-suited for some field environments. Psychophysical force-recall techniques may provide alternatives to handle instrumentation. A thorough understanding of the effects of vibration and other factors on force-recall accuracy and reliability is important before such methods are applied in risk assessments. Methods In this study, the effects of vibration and other factors on the accuracy of psychophysical force-recall were explored in two experiments. Twelve male subjects participated in the first experiment. The second experiment employed 20 participants (10 female, 10 male). In each experiment, participants applied specific grip and push forces to an instrumented handle mounted on a shaker system. Participants were exposed to sinusoidal vibration at frequencies that ranged from 0 Hz to 250 Hz. Three levels of applied force (low: grip = 15 N/push = 25 N, medium: grip = 30 N/push = 50 N, and high: grip = 45 N/push = 75 N ) and two levels of vibration magnitude (low: ANSI 4-8-hr limit and high: ANSI <0.5-hr limit)3 were examined. During the vibration exposure period, participants were provided with visual feedback while they attempted to “memorize” the applied grip and push forces. At the conclusion of the vibration exposure/force memorization period and a controlled rest period, the participants tried to duplicate the grip and push forces on a non-vibrating handle without the aid of visual feedback. The effects of different vibration frequencies, vibration magnitudes, and grip and push force levels were tested in a random order from trial to trial. Results Participants tended to overestimate grip and push forces. Depending on exposure conditions, error means ranged from 2 N to 10 N. The ANOVA revealed that force-recall errors for exposures between 31.5 Hz and 63 Hz were significantly higher than those at other vibration frequencies (p < 0.05). The frequency effect is depicted in Figure 1. Error means were greater when participants were exposed to the higher vibration magnitude (mean = 9.1 N, 95% CI = 8.2-10.1 N) when compared with the lower vibration magnitude (mean = 4.9 N, 95% CI = 3.9-5.8 N) (p < 0.05). The effect of vibration magnitude is shown in Figure 2. The average error for

Jan 6, 2006

Late in 1974 at a meeting with the Cedar Coal Company in Chelyan, West Virginia, a very definite requirement for an automatic heat sensing fire suppression system for the type coal augers used in their mine was revealed. Several fires had been experienced, and while equipment loss was a consideration, operator safety was also a concern. As of that date no one had developed an automatic system specifically for fire suppression on coal augers. II. EQUIPMENT DEVELOPMENT As a result of the above meeting, an unsolicited proposal was made to the Bureau on March 1, 1975, and a contract was issued to provide the following services: A. Determine and define fire hazard problem on Compton Coal Auger. B. Modify or otherwise mike a Lease "AFEX" system suitable for protecting the fire hazard area developed in paragraph "A". C. Make installation of "AFEX" system. D. Monitor installation for reliability for a period of 90 days after installation. C. ConJurt a simulated fire test to determine effectiveness on system.

Jan 1, 1975