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By W. P. Diamond, S. L. Cario, F. Garcia, J. D. Byars, T. P. Mucho

The National Institute for Occupational Safety and Health (NIOSH) has been conducting research at a Pittsburgh Coalbed longwall mine to evaluate and optimize bleeder ventilation and gob gas venthole longwall methane control systems. Gas flow into these two methane control systems was investigated using a combination of Sulphur Hexafluoride (SF6) tracer gas studies and gob venthole pressure monitoring experiments. The insights gained from this research has facilitated the development of along wall subsided strata methane control system conceptual model. This model provides the basis for design suggestions to increase the efficiency of the gob gas venthole system to permit the bleeder ventilation system to become a "safety net" for methane control.

By Naoki Hosoya, Setsuo Maeda

This paper addresses establishment of an experimental system for measuring biodynamic response (BR) of hand-arm system at the NIIH in Japan. BR measurement system at the NIIH is nearly equivalent to NIOSH installed system. The feasibility of the system is examined through the apparent mass (AM) measurement of the empty handle and a set of calibration masses. Apparatus The grip force was measured by using the handle shown in Fig. 1. The handle has two force sensors (KISTLER, 9212) and one accelerometer (PCB, 356A12). A low-pass filter with 5 Hz cut-off frequency was used to the grip force from measured force signal. Figure 2 shows BR measurement system in this study. The push or pull force at the handle was measured by using the force plate (KISTLER, 9286AA). The grip force and the push / pull force were displayed on a monitor. The shaker (IMV, VE-100S) is used to vibrate the hand-arm system along the forearm axis (Zh direction) (ISO 10068, 1998; ISO 5349-1, 2001). In most situations force actions for operating tools are expressed by grip, push, pull and combined these actions. These actions can be simulated in the test system. AM was obtained by performing H1 estimator in the PULSETM system (B&K, 3109) and it is denoted at the one-third octave band center frequencies. [ ] Methods In order to investigate the reliability of the system, AM measurement of the handle was performed. It is assumed that the handle is rigid in the upper limit of adoptive frequency range in this study. This assumption is validated in AM measurement of the empty handle. A pseudo-random vibration in the frequency range of 10 to 1,250 Hz was used and its amplitude is 1.0 (m/s2)2/Hz with a flat power spectral density (PSD) in the experiment. Measured AM includes the mass effect of the measuring cap in a subject experiment. Compensated apparent mass AMc(?) is obtained by Eq. (1) 1-2.

Jan 6, 2006

By P. -É. Boileau, S. Mandapuram, Shiping Ma, S. Rakheja

The absorbed power (PAbs) has been suggested as a better measure of human responses to whole-body vibration, since it relates to the cumulative energy dissipated by the body exposed over a given duration. Moreover, unlike the other measures, the PAbs can adequately account for the intensity of exposure. Although, the vast majority of off-road vehicles impose considerably severe vibration along the horizontal axes, the vast majority of studies on biodynamic response characterization consider only vertical vibration. Only a few studies have reported PAbs responses of the seated human body exposed to horizontal vibration and the major contributing factors [1]. This study aims to characterize the PAbs responses of seated human subjects to horizontal (uncoupled x- and y-axis) vibration as functions of the vibration intensity, subject mass, seat height and the, type of back support. Methods Experiments were conducted using a rigid seat with an adjustable backrest inclination and seat height. The seat was installed on a horizontal vibration simulator and the forces at the seat base and the backrest were measured by three-axis force plates. Two single-axis accelerometers were installed on the seat back and the platform, oriented along the axis of motion. The experiments were performed using three different seat heights (350, 390 and 410 mm), back support conditions (NB- no back support and sitting erect; Wb0- Upper body supported against a vertical back support; and WbA- back supported against an inclined backrest, while sitting relaxed) and three different magnitudes of broad band excitations in the 0.5-10 Hz frequency range (0.25, 0.5 and 1 m/s2 rms acceleration under x-axis and y-axis, applied independently). A total of 8 healthy adult male volunteers with total body mass ranging from 59.4 kg to 92 kg and aged between 21-51 years took part in the experiments. The subjects were seated with their hands in lap, and feet supported on the moving platform for each posture. Each measurement was repeated 2 times, while the data were analysed using a bandwidth of 50 Hz and frequency resolution of 0.0625 Hz. [ ] The data were analyzed to derive the absorbed power characteristics of the body at both seat pan and backrest interfaces, while the coherence among the measured forces and accelerations wer

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 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 Terry R. Neumann

During 1983, U.S. Bureau of Mines personnel examined mines, prospects, and mineralized zones to evaluate the mineral resources and potential of the Funeral Mountains Wilderness Study Area (WSA), Inyo County, California. Eleven mineral properties and two mineralized zones were examined during this study. Of these, six are within the study area and seven adjacent. There are no active mines, in the WSA, nor is there evidence of past production from any claim within the study area. The WSA contains no identified mineral resources. However, occurrences of bentonite, zeolites, and strontium were found in the area. There is little likelihood for resource development of any occurrence in the WSA. The area, in the Basin and Range Physiographic Province, is dominated by a Paleozoic marine sequence. Segments of Tertiary continental fluviolacustrine sediments, including volcaniclastic rocks, abut and overlie the Paleozoic rocks in fault controlled basin areas. Significant concentrations of bentonitic clay and zeolites occur as alteration products in Tertiary tuffaceous sedimentary rocks. However, they are generally low-grade, thin, and discontinuous, precluding commercial development. Limestone, quartzite, and sand and gravel in the area are suitable for many types of construction uses, but similar deposits outside the WSA are closer to markets. No energy resources have been identified in the WSA.

Jan 1, 1984

By Fred N. Kissell

In This Chapter [Measuring the gas emission from the coal Methane at the top of the silo Methane at the load-out area and Actions taken after a silo explosion] Methane accumulations in coal silos have resulted in the occasional silo explosion. These can be quite violent and dangerous because coal dust adds to the strength of the blast. However, with the appropriate precautionary measures, methane accumulations in silos can be greatly reduced. Mine Safety and Health Administration (MSHA) regulations at 30 CFR2 77.201 require that the methane content in the air of any coal silo be maintained below 1.0 vol %.3 Also, MSHA requires that methane tests be conducted before any electrical equipment is energized, unless a continuous monitor capable of deenergizing the electrical equipment is used.4 Measuring the gas emission from the coal. The first necessary step in dealing with silo methane issues is to measure the gas emission from the coal going into the silo. Such measure-ments allow one to estimate the silo ventilation needs and permit a comparison with the methane controls used at other mines that have similar gas levels. The gassiness of the coal can be measured by taking conveyor belt grab samples.5 Matta et al. [1978] measured the gas emission from conveyor belt grab samples using a simple desorption test. To conduct the test, they collected several grab samples of coal, weighing a few pounds each, from the conveyor belt entering the silo.6 They then sealed the coal into an airtight sample container that was equipped with a valve and short hose along with a pressure gauge. Every few hours they opened the valve and bled the emitted gas into a water-filled graduated cylinder that had been inverted and placed in a pan of water (Figure 11–1). The results are shown in Figure 11–2.

Jan 6, 2006

By Magnus Persson

ISO8662-4, “Hand-held portable power tools - Measurement of vibrations at the handle - Part 4: Grinders” is under revision. The new revision shall harmonize ISO 20643 “Mechanical vibration - Hand-held and hand-guided machinery - Principles for evaluation of vibration emission” which, among others, requires measurements in three directions and declared values related to the upper quartile of real-use vibration. To get the most suitable test method, a round robin test was made for evaluation of the two test methods proposed by the ad-hoc group working with this standard revision. Methods Seven laboratories measured the vibration from four grinders of different sizes, with and without autobalancing units. The laboratories come from universities, health & safety laboratories and grinder manufacturers. Two measurement methods are evaluated with respect to repeatability and reproducibility: 1. Grinding on a well-defined mild steel bar with depressed center wheels according to detailed test instructions. The test sequence starts and ends with 10 seconds of running the grinder in the air, when measuring the unbalance contribution to the vibration coming from the unbalance of the grinding wheel. Between these runs the average vibration during 60 seconds of grinding is measured. Three operators do five grinding tests per grinder. 2. Measurements using an aluminum unbalance disc similar to the one defined in ISO8662-4. Each operator runs the grinder four times, between each run the unbalance is moved 180 degrees to avoid variations caused by the play between the test wheel and the spindle. The averaging time is 10 seconds. Each grinder is tested by three operators. Repeatability is the spread within a lab between operators and over short time period for one machine and reproducibility is the spread between laboratories and over longer time periods for one machine. Instrumentation and transducer location are chosen according to ISO8662-4 and circulated test instructions. Results Both the repeatability and reproducibility is poor for the real grinding test, see figure 1. The coefficient of variation for repeatability is approximately 40% higher for the grinding test and the coefficient of reproducibility is 60% higher for the grinding test than for the unbalance disc test.

Jan 6, 2006

By Sheridan J. Rodgers

Toxic fumes generated during shot firing under actual mining conditions were measured. Eight shots with Gelodyn-2X and seven shots with Tovex-100 4VT were monitored. Average CO values for Gelodyn-2X and Tovex-100 4VT were 0.20 ft3/lb and 0.09 ft3/lb, respectively. Average N0x values for Gelodyn-2X and Tovex-100 4VT were 0.049 ft3/lb and 0.026 ft3/lb, respectively. The results obtained with these in-mine tests will be used by the U.S. Bureau of Mines in the development of a large chamber method of measuring fumes from shotfiring of explosives.

Jan 1, 1977

By Tyler Blake

This report describes a study designed to evaluate a pro-posed modification in the cap lamp battery cord intented to reduce the incidence of snagging and catching of the cord. A three phase evaluation was performed comparing a prototype with the standard, currently available cord. First, a ?pull test? equipment was run. The second evaluation was a body conformity study. The third evaluation involved subjects performing common tasks in a low seam coal mine simulator. The results of these evaluations clearly demonstrated significant safety advantages of incorporating coiled cord into the design of the cap cord. The coil cord presented less of a snagging hazard, allowed the wearer more time to respond to a snag, and transmitted lower levels of force to the helmet when snagged. The research team recommended that cap lamp cords be commercially developed which incorporate coiled cord at the battery and helmet.

Jan 1, 1980

By G. L. Oldright

As a rule, the usual zinc retort smelter fired with natural gas made its own burners, of which there might be 300 per block, out of standard pipe fit-tings. The gas was discharged through a feeder pipe at various distances into a cylindrical horizontal "blow hole" through a pillar block and thence into the furnace; the best location of this gas-feeder pipe was at the horizontal central axis of the blow hole; the side entry into the blow hole usually was used. The air entered the same blow hole behind the gas, through a short nipple, in the inner end of which was a constructing orifice in a clay plug; in this ,work cone-shaped funnels of various lengths also were used. Even with the air and gas correctly proportioned to each burner, small differences in their dimensions were found to influence greatly the temperatures reached, their uniformity, and consequently the percentage of zinc extracted. This fourth paper of a series on cooperative work in the zinc retort plants of the Eagle-Picher Mining & Smelting Company discloses the methods and principles followed in approximating closely the optimum dimensions for various burners, with examples from experimental and commercial furnaces showing the interrelation of such dimensions with combustion and temperatures in the furnace.

Jan 1, 1948

By C. S. Compton, T. E. Marshall, D. R. Dolinar, R. Grau, L. J. Prosser, A. T. Iannacchione, D. C. Oyler

Unrecognized roof beam failures resulted in 69% of the falls of ground injuries occurring in underground U.S. stone mines from 1990 to 1996. Field investigations at 45 underground stone mines suggest that excessive beam sag or deflection is the principal unstable roof behavior characteristics associated with miner injuries. Laminated roof structures, common in most underground stone mines, allow the immediate roof to separate into distinct beams. The timely determination of roof beam deflection could provide stone miners with advanced knowledge of potentially hazardous roof. Existing methods to assess roof conditions consist of observational and monitoring techniques. Observational techniques include open drillholes, sounding, wedging, and borescopes. Monitoring techniques include scratch tools, extensometers, telltales, Miners Helpers, and Guardian Angels'. Miners have difficulty utilizing these techniques because roof beams are located an average of 8 m (26.5 ft) above the miner's head in environments that are dark, dusty and noisy and these deflections are measured in millimeters of movement. To help mitigate the potential for falls of ground injuries to underground stone miners, the National Institute for Occupational Safety and Health (NIOSH) has developed the Roof Monitoring Safety System (RMSS) to aid in monitoring dangerous levels of roof beam deflection. If enough site-specific information is collected and placed on highly visible maps, individual mining operations could establish general guidelines for responding to specific roof beam deflection occurrences. This would help in implementing a pro-active, comprehensive roof control plan for reducing falls of ground injuries.

By R. R. French

The industrial minerals industry in the Atlanta, Ga., area was studied in order to better understand problems associated with exploiting mineral resources in and near metropolitan areas. A method for delineating the Atlanta urban area and its component parts was developed so that the factors affecting the location of the minerals industry could be viewed mere objectively in the urban context. Major attention is focused on the area's dominant crushed stone subindustry Demographic and socioeconomic analysis of the Atlanta, Ga., area shows that expansion of the metropolis and its environs will probably eliminate potential mineral resources from the mineral resource base in the area, and that the expanding metropolis will be the primary determinant of future mining sites. Competition for land is accentuated to varying degrees by the incompatibility of wining operations with residential and other environmental requirements. Areas of consideration are suggested to provide maximum development of land and resources for greatest economic benefits it minimum social cost. Further research is recommended to determine market locations in urban areas, optimum operating levels for industrial minerals plants, and alternatives to surface mining.

Jan 1, 1970

By J. W. Town

This report summarizes the results of laboratory investigations made by the Bureau c! Mines on the recovery of mercury from caustic sulfide solutions by aluminum precipitation and by electrodeposition. Statistical methods were used to design the experiments and evaluate the resulting data. Precipitation studies demonstrated tint metallic mercury could be recovered from mercury sulfide-sodium sulfide solutions with aluminum. Other metals and their salts and aluminum, salts precipitated only black mercury sulfide. Over 95 percent of the mercury was precipitated from solutions prepared with reagent-grade chemicals and from cinnabar leach solutions. Two equivalents of aluminum were required to obtain 95 percent precipitation of the mercury. Under optimum conditions 1 gram of aluminum precipitated from 4 to 7 grams of mercury; the excess Aluminum was recovered for reuse. The effects of time and temperature on the precipitation of mercury were minor when compared with the effects of mercury concentration and aluminum equivalents. The particle size of aluminum had no significant effect over the ranges studied. When aluminum was used as a precipitant, the mercury concentration in solution was reduced to below 1.0 grams per liter. Adding arsenic and antimony sulfides to the mercury solution resulted in their coprecipitation with the mercury when the aluminum was added From 95 to 99 percent of both the arsenic and antimony were precipitated as metal, which amalgamated with the mercury.

Jan 1, 1962

By Doss H. White

In 1989, Alabama's nonfuel mineral industry produced a State record of $463 million of nonfuel mineral commodities, an increase of $4 million over that reported by the State's mineral producers in 1988. The new record marked the fourth consecutive year in which mineral production increased over that of the previous year. Alabama ranked 22d among the States in total mineral value. Cement, stone, and sand and gravel were the three leading mineral commodities produced, accounting for 77% of Alabama's total mineral value. During the year, there were several acquisitions by Alabama cement and stone companies, and the only tantalum mine in the United States completed its first full year of operation.

Jan 1, 1991

To allow the controlled yielding of mine walls in order to reduce rock-burst hazards and reduce maintenance caused by excessive squeezing forces. Approach Rock bolts that elongate and continue to sustain a load, have been fabricated and tested. This device is an adoption of a concept originally developed in South Africa for use where unusually adverse conditions may warrant the added cost. How It Works A coupling in the rock bolt allows controlled elongation if the load increases beyond the bolt's design strength. (The load can build up either slowly, as during heaving, or rapidly, as before a rock burst.) The elon¬gation of one or more rock bolts surrounding a mine opening, allows the rock to move from its original position to c new position in a controlled manner. This movement relieves the rock stresses, and the mine opening reaches a new state of equilibrium. The elongatible coupling of the rock bolt consists of a

Jan 1, 1977

By H. J. Lechtenberg

Preliminary results are given of solvent stimulation of two wells producing viscous oil (14°-17° API) from the Tar zone in the Wilmington field, California. The solvent (coker oil, an intermediate refinery product) was injected into the formation, and after a soak period, the well was returned to production. Data are given on crude oil properties, solvent properties, determination of volume of solvent in the produced oil, rate of oil production before and after stimulation, volume of additional oil produced, and volume of solvent recovered. Although further study and improvement of the method arcs needed, cyclic solvent stimulation appears to be an unqualified success in one well and a moderate success in the other.

Jan 1, 1972

By G. W. Jones, R. E. Kennedy

"INTRODUCTION In the manufacture, storage, transportation, and use of combustible gases and vapors, explosion hazards, which at times may be present when air becomes mixed with the gases and vapors, become of primary importance. Such conditions are especially dangerous where large volumes of gaseous atmosphere are involved, because an explosion under such circumstances is capable of doing tremendous damage to both property and personnel.Because of its interest in safety in the mining and allied industries, the Federal Bureau of Mines has investigated, and published results dealing with, the explosibility of various types of combutible atmospheres. The explosion hazards of natural gases have received attention, and results giving the limits of inflammability and ignition temperatures in air have been determined and published. 4/ Other investigations have shown how explosions of natural gas-air mixtures may be prevented by the addition of nitrogen and carbon dioxide. 5/Because of the increased demand for crude oil for war purposes, the application of secondary-recovery methods of stimulating oil production have received considerable attention during the last few years. The process consists in the injection of natural gas into partly depleted oil wells to cause the oil in the sands to flow into producing wells and so increase the amount of recoverable oil. 6/"

Feb 1, 1945

In This Chapter [Finding the dust source Ventilation and dust collector malfunctions Upgrading the dust controls Design stage ventilation planning ] This chapter explains how to reduce respirable dust76 in hard-rock tunnels during excavation by using tunnel boring machines (TBMs). The first steps in combating a dust problem are to take dust samples to pinpoint the source, check the ventilation system, and check the dust collector. If the ventilation system and dust collector are operating properly, then other dust controls such as water sprays and conveyor belt scrapers must be upgraded. For tunnels in the design stage, recommended air quantities are provided. FINDING THE DUST SOURCE AND LOOKING FOR VENTILATION MALFUNCTIONS [The first steps in fighting a dust problem are to take dust samples to pinpoint the source, check the ventilation system, and check the dust collector. Without knowing the exact source, efforts to reduce dust are hit-and-miss (mostly miss).] Taking samples to pinpoint the dust source. In tunnels with high levels of airborne dust, the first task is to pinpoint where the dust enters the airstream. Most dust originates from rock breakage at the tunnel face, but the location where this dust enters the airstream can vary. Dust can leak from behind the TBM face shield, from gaps in the ventilation duct, or from a mal-functioning dust collector. It can be entrained into the air from the muck on a moving conveyor belt. It can even be shaken loose from the underside of the belt as it passes over the idlers. As a start, to locate the dust source, dust samples and air quantity measurements should be taken at the following locations:

Jan 6, 2003

By Robert L. Lagace

The objective of this task was to perform theoretical analyses related to identifying and increasing the understanding of wireless propagation mechanisms in mines, and for predicting the performance ranges and limitations of proposed systems. This was to be achieved by building on and extending previous ADL work* and utilizing experimental data as they became available in the radio frequency bands of interest. B. TASKS Theoretical radio wave propagation investigations undertaken on this task centered on three areas. The first area dealt with extending previous UHF wireless propagation results*: to estimate the losses caused by the presence of haulage vehicles such as trains in coal mine tunnels; to estimate the propagation losses and wireless communication ranges expected along a longwall coal face tunnel; and to assess the applicability of previous analytical approximations to tunnels having reduced crossectional dimensions, such as those found in low coal and in the presence of haulage vehicles. The second area dealt with the development of a suitable propagation model to adequately explain the unexpected, highly favorable LF to MF band wireless radio wave propagation behavior experimentally observed in Consolidation Coal Co.'s Ireland mine. The third area dealt with the formulation of a model for evaluating the overall system transfer function and transmitter requirements for a hoist shaft LF communications system, taking into account the hoist rope/shaft transmission line characteristics, the cage and sheave wheel line terminations, the signal inductive couplers, and hoist shaft signal and noise data.

Jan 1, 1975