Search Documents

By R. V. Ramani

The overall objective of this study is to contribute to the reduction of the quartz dust hazard in underground coal mines through a better under-standing of the sources and generation of airborne quartz dust. This research project has included extensive experiments in operating mines for (1) documenting the amount of respirable dust generated, (2) measuring the quartz levels in host materials and airborne dust, (3) analyzing the size consist of the mined product, and (4) establishing the relationship between these various parameters. The results of the study indicate that the amount of dust airborne is a very small fraction of the total (<15 µm) and respirable (<7 µm) dust generated. The quartz contents in the total and respirable airborne dust are generally higher than those in the host material. Quartz content increases with decreasing size of airborne dust. Also, it appears that rock breaks into a different size distribution than coal. The source of quartz for the airborne dust appears to be the roof and the floor material rather than the coal seam itself. No general relationship is found between the Hardgrove Grindability Index and either the quartz content in the airborne dust or the amount of respirable dust. Extended descriptions of the experimental design, the experiments, data analyses and results are presented in this volume. The raw data, the data management computer program and the sampling and safety plan are presented in Volume 2.

Jan 1, 1987

By Kazunori Matsushita, Masaru Sakakibara, Kenji Harada, Naotoshi Shinkawa, Mitsuo Nozu

The Sand Compaction Pile (SCP) method has been widely used as a typical countermeasure against liquefaction in Japan, and its effectiveness has been confirmed in many case histories of damages caused by the past large-scale earthquakes. A series of studies were conducted to evaluate the effectiveness of the compaction method and other factors, if any, in sustaining a seismic force that is greater than the assumed one and caused no damage. Based on the results of these studies, the Architectural Institute of Japan (AIJ) has indicated in its “Recommendations for Design of Ground Improvement for Building Foundations” published in 2006 that the liquefaction resistance ratio (tl/sz) of the composite ground, which consists of sand piles and surrounding compacted ground, is higher than the RL calculated by using the SPT N-values of the ground in-between the sand piles. In this paper, statistical analysis of safety factor against liquefaction, FL, was performed by using the SPT N-values of ground in Port Island and Rokko Island which were both fully reclaimed islands in Kobe city during the 1995 Hyogo-ken Nambu Earthquake (classified as intense shaking) and, together with the consideration of relative settlement, resulted in tl/sz of the composite ground being 1.5~2.5 times of tl/sz of the soil in-between piles after improvement. Furthermore, the liquefaction resistance curve of SCP-improved sites obtained from the relationship between SPT N-values and cyclic shear stress ratio during the 2011 off the Pacific Coast of Tohoku Earthquake, which was regarded as long-duration earthquake, was plotted to the left side of the curve originally proposed by Japan Road Association. Thus, the liquefaction resistance of the improved ground was found to be higher than that of the natural ground, even for the same SPT N-values, verifying the validity of the AIJ recommendation.

Jan 1, 2017

By J. E. Hoffman

The operation of the U .S Metals Refining Company, USMR Co. is defined below by the description of a variety of unit processes and operations the author encountered during his tenure with the operation, 1955 - 1978. The operations discussed include: sampling and sweating of radiators, processing of Indian Coin, treatment of insulated wire, baghouse and converter dust treatment, blast furnace and converter operation, the electric arc furnace, antimony control, selenium and tellurium products, electrolyte liberation with soluble anodes, and the precious metals refinery. These operations, although peripheral to the primary copper production circuit, were critical to the company's technological and economic base.

Jan 1, 2000

By C. B. Webber, W. A. Grell

"Sherritt Gordon's Ruttan Mine is a copper-zinc operation located approximately 600 miles north-west of Winnipeg. Open pit mining began in 1973 at 10,000 Tpd., with a change over to underground mining in 1981 producing 7,500 Tpd. Ore is crushed to -3/4"" followed by rod and ball mill grinding (two ball mills in series), differential copper-zinc flotation, and dewatering. The copper and zinc concentrates are trucked 75 miles to Lynn Lake, where they are shipped by rail to the HBM&S smelter at Flin Flon.This paper describes a method used to predict the effect of grind particle size on metallurgical performance, as well as details on the copper and zinc metallurgical performance due to fine grinding in actual plant operation.Initial statistical studies on historical data (including ore source, head gr3de, grind, etc.) indicated that copper and zinc recoveries increased with fineness of grind, in the range of 50 to 65% -200 mesh.In order to extrapolate beyond 65% -200 mesh, and to develop expected nonlinear relations between grind, Cu concentrate grade, and recovery, the assays of screen fractions of copper concentrate and tailing were used to determin8 the relation between net smelter return (a function of grade and recovery) and grinding cost. The optimum economic grind would be that grind at which the net smelter return less grinding cost reached a maximum."

Jan 1, 1982

[Participating Scholarship Colleges and Universities 138 AmerCable 130 Andalex Resources, Inc 82 Behre Dolbear & Company, Inc 83 Commercial Testing & Engineering Company 86 Continental Conveyor & Equipment Co 87 Crane & Hoist Sales Inc 12 Crested Butte Mountain Resort 88 Dakota Coal Company 89 Empire Machinery Company 90 Energy West Mining Company 91 GH Hensley Industries 92, 93 Hitachi Construction Machinery (America) Corp 96 Ingersoll-Rand Company 131]

Jan 1, 1998

Jan 1, 1961

By R. Owen

An overwhelming amount of data can be collected around the blasting process. This information can include blasting product, pattern design, blast results, and routing. It is only when these data sources are combined in a concise and accurate form that they are of real use in determining the safety and economic implications of each parameter. Two key technological aspects of blasting are drill fleet management (DFM) and size fraction analysis (SFA). As these technologies are integrated as near-real-time measurement and QA/QC tools, the resolution and realization of blasting parameters is significantly increased. The Freeport-McMoRan Morenci Mine has integrated these technologies along with other existing database structures to create a responsive and sustainable tool for reconciliation, forecasting and parameter matching. This ability allows Morenci to customize blast patterns to meet the criteria most critical to each shot, whether the impact is influenced by routing and recovery, equipment maintenance or safety concerns. DRILL FLEET MANAGEMENT The current DFM was stabilized in its current form in mid 2009 after database and hardware maintenance met stability requirements. Currently the system is running on 12 production drills. The system receives pattern layout and is capable of semi-autonomous drilling over the entire district. The fleet is capable of drilling in highly altered intrusive units and hard granites through the range of sedimentary and volcanic units that comprise the Morenci District. The system brings a level of accuracy not achievable with earlier paint-marked patterns. Depth control is also increased along with more consistent wear and maintenance patterns due to semi-autonomous drilling.

Jan 1, 2011

By Danny Riley, Brian Curry, Sandya Govindaraju, James Bain

Hand arm vibration syndrome (HAVS) affects industrial workers exposed to long term hand-transmitted vibration from powered-tools. Peripheral neuropathy is a major component of the symptom complex of HAVS. Long term exposure to vibration causes myelin damage in peripheral nerves and reduces nerve conduction velocities in rats1. This study addresses the effects of acute vibration at constant acceleration of 49 m/s2 on myelinated fibers in peripheral nerves in Sprague-Dawley male rats using the ‘rat-tail vibration model,’ which simulates hand-transmitted vibration2. Methods Male Sprague-Dawley rats (~300 g) were assigned to vibration groups: 1 hr continuous vibration at 60 Hz; 4 hr continuous exposure at frequencies of 30, 60, 120 or 800 Hz; immediate and 24 hr following a 4-hr cumulative exposure of continuous and intermittent vibration at 60 Hz. Unanesthetized rats were restrained in cages on a nonvibrating platform with their tails placed on a vibrating stage accelerated by a B&K motor type 4809 and vibrated. Intermittent vibration was delivered in bouts of 10 min vibration alternating with 5 min rest periods repeated over 6 hr. Sham controls were restrained without vibration. After vibration exposure, the rats were anaesthetized, and the ventral nerve trunks from the proximal tail segment 7 were fixed in glutaraldehyde, embedded in epon-araldite and sectioned at 0.5 µm thickness and stained with toludine-blue for morphological quantitative analysis. The total number of myelinated axons in each cross-section of the nerve was counted using the Image J software. Myelin damage was identified by focal increase in area and intensity of toludine-blue staining and unraveling of the myelin sheath. Statistical analysis for comparing sham and the different vibration groups was done using Dunnett’s test. Animal treatment and all surgical procedures were approved by the institutional review board and compiled with the Laboratory Animal Welfare Act. Results The rats tolerated continuous vibration very well and exhibited no behavioral signs of stress. When exposed to intermittent vibration, there was increased vocalization, a startle reflex at the beginning of each bout of vibration, deposition of porphyrin around the eyes and transient hypersensitivity to touch.

Jan 6, 2006

By Jorge R. Falla

El presente texto describe la importancia de la relación entre la minería y la tecnología en la actualidad -en tanto que la primera es una actividad económica que moviliza los recursos financieros, sociales y técnicos en la sociedad, mientras que la segunda, influye en las fases operaciones mineras. En ese sentido, los cambios tecnológicos desarrollados por la industria minera afectan a la comunidad a partir de sus componentes sociales, económicos y ambientales, así como de sus relaciones comunitarias, de forma que pasa del asistencialismo de la minera a una asociación de mutuo beneficio.

Sep 13, 2001

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 Pharis E. Williams

The ability to predict the performance of an explosive relies upon having a Reaction Rate Law and knowing its functional dependence upon various parameters of the explosive. In particular, emulsion explosives have a matrix cell size and may be sensitized with glass or plastic microballoons. The cell size dependence should. be very nearly the spherical grain burning dependence upon web that appears in the reaction rate laws for ball gun powder. The dependence of the reaction rate law upon the parameters of the sensitizing microballoons has been explored using hydrocode analysis of the pressure field produced by the collapse of a microballoon. This pressure field provides an increase in pressure in the vicinity of the microballoon which, in turn, increases the rate of reaction within this field and provides the energy release that must be achieved in order to have a steady state detonation for use as a blasting agent. Hydrocode analysis allows the determination of an approximate functional form for the reaction rate law which shows the dependence upon the size, type, and quantity of microballoons. This presentation includes the theoretical background and the determined functional form of the reaction rate law.

Jan 1, 1995

Jan 1, 1969

By Jr. Abel

Subsidence is controlled by a complex combination of mining and geologic factors. For example, a world-wide compilation of data shows that, as the percentage of shale in the overying rock mass decreases and the amount of sandstone increases, the angle of draw (and the area affected by subsidence) decreases. Limestone in the overburden appears to cause as much as a three-fold decrease in the angle of draw compared to a like amount of sandstone. Increased amounts of sandstone were accompanied by a greater surface subsidence relative to the mining height. The total thickness of overburden did not appear to influence the subsidence magnitude above super-critical panels. The greater the thickness extracted the smaller percentage of that thickness that shows up at the surface as subsidence. The greater the percent of the seam extracted, the greater the subsidence reaching the surface. The maximum subsidence above room and pillar panels is dependent on the pillar height and minimum width as well as the other factors listed.

Jan 1, 1980

By Dennis R. Dolinar, Christopher Mark, Gregory M. Molinda

Despite more than half a century of experience with roof bolting, no design method has received wide acceptance. To begin to improve this situation, National Institute for Occupational Safety and Health (NIOSH) conducted a statistical study of roof bolt performance at a number of mines throughout the U.S. Case histories were collected from 37 mines with a variety of roof bolt types and patterns in a wide range of geologic environments. Performance was measured in terms of the number of roof falls that occurred per10,000 ft of drivage. The study found that roof falls are rare when the roof is strong and the stress is low, even with light roof bolting patterns. The focus of this paper is on the more difficult conditions, where the roof is weaker and/or the stress is higher. Analysis of the results led to guidelines that can be used to make preliminary estimates of the required bolt length, capacity, and pattern. The guidelines are based on the depth of cover (which correlates with stress) and the roof quality (measured by the Coal Mine Roof Rating (CMRR), and the intersection span. Another contribution is a formula for estimating the horizontal stress level in the eastern U.S. coalfields as a function of the depth of cover. The design guidelines are currently being implemented into a computer program called Analysis of Roof Bolt Systems (ARBS).

By N. A. C. Smith

This report on the physical and chemical properties of typical crude oils of southern Louisiana and southern Texas is the seventh in a series of preliminary chapters of a bulletin covering the producing districts of the United States. Preceding reports* may be obtained from the Bureau of Mines on request. The details of the methods used in this survey in collecting samples and making laboratory tests have been discussed in the first three papers. A method of summarizing and interpreting the laboratory data has also been given, but most of the crudes included in the present report differ so radically from those previously reported, that it has been found advantageous to adopt a somewhat different method in making summaries. This method is described in detail later. If any errors or omissions are noted by readers, it is hoped that these will be brought to the attention of the Bureau of Mines, for correction before the appearance of the final bulletin.

Jan 1, 1922

By J. Sammarco

The U.S. National Institute for Occupational Safety and Health (NIOSH) is conducting mine illumination research to determine if light-emitting diode (LED) cap lamps can improve safety by reducing glare. Glare can impede a miner?s ability to see hazards and to safely perform their work. Another objective is to determine if a person?s age is a factor. This is important because the workforce is aging ? the average miner is now about 43 years old. Three cap lamps were used to evaluate glare: an incandescent cap lamp, a commercially available LED cap lamp and a NIOSH prototype LED cap lamp. Thirty NIOSH personnel from the Pittsburgh Research Laboratory (PRL) served as test subjects. Three age groups were established with ten subjects in each group. Testing was conducted in the Mine Illumination Laboratory (MIL) of NIOSH PRL. The results indicate no statistically significant difference in discomfort glare among the incandescent and LED cap lamps. However, an analysis of variance for disability glare indicates that the LED cap lamps were superior for the older subjects. Disability glare scores for the oldest subject group improved 53.8% when using the NIOSH prototype LED cap lamp compared to the incandescent cap lamp and 36.5% compared to the commercial LED cap lamp. It ap­pears that, given the conditions of this study, LED cap lamps will not increase discomfort glare and can enable significant improvements in disability glare for older workers. It is also evident that not all LEDs are created equal. The disability glare improved the best for older workers when they used the NIOSH prototype LED cap lamp, which has a different spectral power distribution (SPD) (more short wavelength energy) than the commercial LED cap lamp. Therefore, for disability glare, the results suggest that the SPD is an important factor to consider in cap lamp design.

Jan 1, 2009

By Pinnaduwa H. S. W. Kulatilake, Biao Shu

The intact rock properties and discontinuity properties for both Devonian Rodeo Creek (DRC) and Devonian Papovich (DP) rock formations that exist in the selected open-pit mine were determined from tests conducted on rock samples. Special survey equipment, which has a total station, laser scanner and a camera, was used to perform remote fracture mapping in the research area. From remote fracture mapping data, the fracture orientation, spacing and density were calculated using more refined procedures compared to what exist in the literature. Discontinuity orientation distributions obtained through remote fracture mapping agreed very well with the results of manual fracture mapping conducted by the mining company. The GSI rock quality system and Hoek-Brown failure criteria were used to estimate the rock mass properties combining the fracture mapping results with laboratory test results of intact rock samples. Fault properties and the DRC-DP contact properties were estimated based on the laboratory discontinuity test results. A geological model was built in a 3DEC model including all the major faults, DRC-DP contact and two stages of rock excavation. The built major discontinuity system of 44 faults in 3DEC with their real orientations, locations and three-dimensional extensions were validated successfully using the fault geometry data provided by the mining company using seven cross-sections. Numerical modeling was conducted to study the effect of boundary conditions and lateral stress ratio on the stability of the considered rock slope. For the considered section of the rock slope, the displacements obtained through stress boundary conditions seemed more realistic than those obtained through zero velocity boundary conditions (on all four lateral faces). Stable deformation distributions were obtained for k0 in the range of 0.4 to 0.7. Because the studied rock mass is quite stable, it seems that an appropriate range for k0 for this rock mass is between 0.4 and 0.7. The displacements occurred between July 2011 and July 2012 due to the nearby rock mass excavation that took place during the same period; they were compared between the field monitoring results available from the mining company and the predicted numerical modeling results and a good agreement was obtained. Overall, the successful simulation of the rock excavation during a certain time period indicated the possibility of using the procedure developed in this study to investigate rock slope stability with respect to expected future rock excavations in mine planning.

Jan 1, 2015

Jan 1, 1968

Jan 1, 1968

By C. D. Thurmond

Jan 1, 1968