Search Documents

By Oliver Bowles

The United States Bureau of Mines has within its ranks a group of engi- neers who are engaged in working out quarry problems, the solution of which will be of general benefit to the industries involved. The problems undertaken are approached in a systematic and thorough manner, all the evidence for and against any proposed change or new development being collected as carefully as an attor- ney would prepare his data on an important case. Unlike the attorney, however, the Bureau engineer does not take sides; his judgment is based entirely and in- partially on the array of facts presented. In order to gain the desired infor- mation he visits many plants, consults with the leaders in the industry, works out experiments in his laboratory, and supplements this information with a stu- dy of all available literature already published on the subject in any part of the world. As an engineer who has for eight years conducted such inquiries in the stone industry, I propose to discuss the Bureau of Mines viewpoint; and it may be of interest to consider with me in a brief and general way the engineer's method of looking at quarry problems, and some of the results attained through past and present labors. While the Bureau has conducted no investigation directly for the crushed- st one industries, two years of investigative work at cement-plant quarries, and work now being conducted at lire-plant quarries, has a very direct bearing on the problems of the crushed-stone industry, since stripping, drilling, blasting, loading, and transportation are similar in many respects in all stone quarries. The results of cement-plant quarry investigations are to be found in Bureau of Mines Bulletin #160. (b) Two short papers on lime-plant quarry problems have been issued in mimeographed form as Serial #01 (c) and Serial 3 (d).

Jan 1, 1923

By A. T. Iannacchione

Synopsis Underground stone mining Is an emerging sector of the U.S. mining industry. As this expansion takes mines under deeper cover, and as more efficient mining methods are utilized, effective stone pillar design methods will become even more Important. Current design practices are examined and a discussion of safe mine layouts is presented as a first approach towards weighing the demands for increased production against increased risk. Risks to underground stone-mine workers include rib Instabilities, pillar failures and roof falls. Seventy-two stone-mine pillar designs were examined. Pillars with width to height ratios of less than 1.5 appear more likely to fail when subjected to excessive stress levels. When width to height ratios fall below 1.0 defects in the pillars, such as through-running discon¬tinuities, can have a significant influence on stability. Discontinuity persistence, dip, material properties and orientation are also important determining factors in pillar strength. During the past three years the number of active underground stone mines in the U.S.A. has ranged between 90 and 100. This number is expected to increase as the crushed stone industry responds to growing demands for its products.1 As more of the industry moves to benefit from the advantages of underground mining production from underground stone mines is expected to increase above its current level of approximately 66 000 000 r/year. Parker2 identified four advantages of underground mining operations: (1) surface developments, zoning laws and environmental concerns are often less of an issue; (2) stripping and restoration requirements are eliminated; (3) additional reserves are often available beneath the quarry floor, under pit slopes or under an adjoining property; and (4) space is created for secondary use. Underground mines enjoy the added benefits of work in a constant underground climate, rather than in the variable surface climate, minimization of community concerns by placement of the crushing, sizing and stowing operations underground and reduction of surface vibration concerns through smaller blasts. The drawbacks of underground mining include added health and safety hazards for the stone miners, whose health can suffer from increased exposure to falls of ground, airborne contaminants and fog in large underground openings. Injuries from falls of ground in stone mines have occasionally exceeded the incidence rates for other mineral resources mined underground. 3 Existing underground stone operations, by comparison with stone operations a decade ago, mine more stone at a faster rate and with larger equipment. Because of high demand mines face increased pressure to yield more stone per production blast. A majority of the miners use the V-cut blasting pattern, which limits the depth or pull for each shot to about 4 m. Therefore, to produce more stone, either the mines must work more faces or existing faces must be enlarged. The enlargement of underground openings poses problems in the maintenance o€ strata stability, First, the widths of the mine entries partially control the amount of sag or deflection that any given roof beam can withstand before failure. This deflection can take pi ace quickly after an opening is excavated or much later as weathering processes form additional, thinner beams. Because increased deflection increases the potential for roof beam failure, there is a limit to how wide a room can safely be made. These limits depend on local geological and stress conditions and, to some extent, the cost effectiveness of roof-bolting. Given these room width limitations, underground stone mines have placed more attention on expansion of production through benching where mining thicknesses permit. The heights of rooms partially control the strength characteristics of adjacent pillars: as the room height increases for a given pillar width the pillar width-to-height ratio (w/h) decreases. In general, stone pillars are very strong, but when the width-to height ratio diminishes the potential for pillar rib instabilities and pillar failures increases (see Fig. 1). [ ] In the underground environment the desire to utilize wider rooms, higher benches and multi-level mining results in the potential for unstable ground conditions. Although the number of failed pillars is currently very low, the potential for additional failures will grow if more slender pillars are developed, especially under deeper cover, with wider mining sections and in multi-level operations. It should also be noted that the passage of time acts to decrease the strength of many existing pillars. An examination of current design practices

"Minimizing Particle Contamination During Generation of Fresh Dust for Inhalation Studies J. Abraham, MS, Mechanical and Aerospace Engineering, West Virginia University, 1995Correlating Lung Crackle Using Holographic Interferometry Ali Afshari, MS, West Virginia University, 1989Effect of Bit Wear on Dust Generation Mudassar Ahmad, MS, West Virginia University, 1992 The Effect of Surfactants on Suppression of Non-Wettable Particles Ali Alaboyun, MS, Mineral Engineering, The Pennsylvania State University, 1989 Geochemical Characterization of Kerogens, Shales, and Coal Refuse Associated with Allegheny Formation of Cases of Northern West Virginia Dick Andre, MS, West Virginia University, 1987Size and Mass Characterization of Airborne Particulate Matter in Underground Coal Mines Using Diesel-Powered Equipment Indranil R. Bardhan, MEM Report, The Pennsylvania State University, 1992Size and Mass Characterization of Airborne Particulate Matter in Underground Coal Mines Using Diesel-Powered Equipment I. Bardhan, R. V. Ramani, and J.M. Mutmansky, Mining Engineering, The Pennsylvania State University, University Park, PA, Final Report to the U.S. Bureau of Mines, April, 1994Particle Concentrations in a Hazelton Inhalation Chamber Shahram Bavani, MS, West Virginia University, 1985Use and Potential of Lazer Holographic Interferometry and Subsidence Model- Study of an Underground Room and Pillar Mine Richard Begley, MS, West Virginia University, 1984Development of a Mechanistic Model for Prediction of Subsidence in a Longwall Mine Richard Begley, PhD, West Virginia University, 1990Redesign of Micro-Orifice Uniform Deposit Impactor Steve Behm, MS, University of Minnesota, 1991Evaluation of a Two-Phase Spray System for Dust Suppression B. Belle, MS, The Pennsylvania State University, 1996Evaluation of a Two-Phase Spray System for Dust Suppression B. Belle and R.-V. Ramani, The Pennsylvania State University, University Park, PA, Final Report, September 9, 1996A Fracture Mechanics Study of Crack Propagation Mechanism in Coal: The Mechanics of Fine Fragment Formation Z.T. Bieniawski and R. Karl Zipf, Jr., Mining Engineering Department, The Pennsylvania State University, University Park, PA. Final Report, October l, 1988A Mathematical Model for the Prediction of Ambient Dust Concentrations in Mine Atmospheres R. Bhaskar, MS, Mining Engineering and Operations Research, The Pennsylvania State University, 1984Spatial and Temporal Behavior of Dust in Mines-Theoretical and Experimental Studies –R. Bhaskar, PhD, Mining Engineering, The Pennsylvania State University, 1987"

Jan 1, 1998

By By Staff

"This publication summarizes, for potential contractors and all other interested parties, the research, development, and demonstration of in-house and contract projects programmed by the Bureau of Mines for fiscal year 1982(October 1, 1981-September 30, 1982) under its Minerals Health and Safety Technology program. The objective of these projects is to provide an ordered and sequenced series of advance toward the Bureau's overall goal of providing the systems technology required to create a more healthful and safer working environment for the Nation's mining and minerals processing workersINTRODUCTION The Bureau of Mines conducts a balanced, continuing in-house research and development program to accelerate systematic improvements in health and safety conditions in U.S. mines. Part I of this report outlines the Bureau's present in-house effort to all interested parties; in particular, potential contractors can refer to it when submitting USP's (unsolicited proposals), thus avoiding proposing research that duplicates work being performed by the Bureau.It is the policy of the Bureau of Mines to utilize as fully as possible the capabilities of the private sector in minerals research, and to that endPart II of this report outlines the Bureau's current projected contract research needs.The projects presented were planned at the beginning of the fiscal year and are subject to change based on emerging priorities and availability of funds. Contingencies may require that a significant portion of the program be deferred into fiscal year 1983 (FY 83) or beyond. It is important to realize that since this is a summary document, the project descriptions related to a design, fabrications, and demonstration effort do not necessarily imply total package procurement."

Jan 1, 1982

By Hal H. Engel

This publication was written in response to numerous requests for information about the Federal Bureau of Mines' "Demonstrated Lecture on Flame Propagation and Permissible and Explosion-Proof Electrical Equipment." The requests came principally from: (1) Persons wanting to know more about the demonstration before requesting it for groups they represented; (2) persons wishing advance information to help publicize a meeting where the demonstration was to be given; and (3) members of audiences desiring something to help them remember the salient points, facts, and figures presented during the lecture and demonstration. The purpose of the demonstration that accompanies the lecture is to show: (1) Variations in flame speed and pressure at various percentages of flammable gas within the flammable range; (2) effect of flame speed on the "pressure piling" within the area confining the mixture; and (3) the application of flame speed and pressure piling to the combustion of surrounding gas and to the design and maintenance of electrical equipment used in hazardous locations.

Jan 1, 1960

Apply state-of-the-art monitoring and computer systems technology to remotely monitor geostructural data and evaluate ground conditions in near real-time. Background Recently, the coal mining industry has progressed dramatically from a labor-intensive industry to highly mechanized and automated systems achieving significantly higher production rates. In underground longwall coal mines, production and face advance rates have increased by almost tenfold in the last 15 to 20 years. With increasingly high advance rates, geologic anomalies which affect rock mass quality are encountered more frequently, far exceeding the current rate at which ground control information can be processed and analyzed. As a result, mine operators find themselves with insufficient time or resources to cope with the rapidly changing ground conditions. To keep up with the technological advancement in mining and the associated ground control problems, the Bureau of Mines is conducting a multi-phase research pro¬gram to implement a computer-assisted Ground Control Management System (GCMS). Research is ongoing at present, but when completed the system will be designed to 1) monitor and evaluate data on rock properties, geologic conditions, and rock mechanics data from underground sensors in near real-time; 2) interpret the analyses to evaluate the interaction between various critical ground control parameters; 3) assess the structural integrity of the mine; and 4) determine failure modes and provide recommendations for control measures, design modifica¬tions, and alternative support procedures. The system will be expanded into its full capability during various phases of this research program.

Jan 1, 1991

By Tony Keller, Setsuo Maeda

Hand-Arm Vibration Syndrome (HAVS) was identified as early as 1918 in Bedford, Indiana in the U.S. Since then much research work has been done around the world in the areas of medical, epidemiological, engineering and legal aspects of HAVS. In Japan, much of the pioneering work in this field has been performed by Dr. Setsuo Maeda and his staff at the National Institute of Industrial Health (NIIH) in Kawasaki. Most recently, reports of work done by this group and by Dr. Ren Dong1 of NIOSH in the U.S., as well as many other suppliers and Japanese practitioners were presented at the 13th Japan Group Meeting on Human Response to Vibration held in Osaka2 during August 3-5, 2005. [ ]

Jan 6, 2006

By J. F. Barkley

The following questions and answers were prepared principally to supply information in answer to general inquiries received by the Bureau from those contemplating the use of propane and butane fuels . Primary or basic information only is covered; this usually gives enough guidance for most inquirers . To those who wish information of the treatise type , the handbook , Butane- Propane Gases , published by the Jenkins Publications , Inc. , 1709 West 8th Street , Los Angeles 14, Calif . , is suggested .

May 1, 1949

By R. V. Ramani, V. T. Burgos, J. A. McClay

The systems contributing to the cost analysis, and the flow of data input and output related to these systems, are brought into focus in Figure 6. The various sub-systems of the Master Design Simulator provide the raw operating data basic to the cost model which, operating independently, accumulates the raw input, assigns costs to this data by standard or modified costing procedures, manipulates the costs into standard formats and outputs the data for managerial evaluation. Cost Modeling Direct costing methods are not complex in the sense that elemen¬tary arithmetic is employed using the same basic relations for each cost category. The basic cost model relations described above are illustrated in Figure 7. The greatest difficulty encountered in the transition from a dy¬namic systems simulation model to a costing model is the time frame of the input and output data. Dynamic simulation models utilize a small time increment, on the order of seconds or fractions of seconds, to analyze system operations and interactions. On the other hand, for cost computation and reporting, the smallest relevant time unit is the shift, with reporting periods expanding to days, weeks, months, and years. Complications arise in the accumulation of data for the various report periods due to the use of the Gregorian calendar by modern so¬ciety. The potential for simulation for the life of the mine, possibly in excess of 50 years, increases the complexity of the costing process

Jan 1, 1975

By Lloyd A. Morley, Alan M. Christman

General Six open-pit metal mines, five copper and one molybdenum, were visited during the course of the research. Four were investigated twice, in summer and in winter, in order to determine the effects of seasonal variations In temperature and moisture upon the measured parameters, Permission to enter the fifth mine was received too late to make an examination during the summer months. The sixth mine was visited to confirm the results obtained from the other five and specifically, to observe how the project recommendations (as will be presented in this chapter) would apply to open-pit metal mines in general. Information gathered during the ten plant visits is sufficient to form an adequate data base for the report. A complete presentation of all field trip data is given in Appendix 1. Further, a detailed description of the electrical distribution and grounding practices at each mine is also contained there. Typical System. At a typical mine as shown schematically in Figure 62, one or more substations with resistance-grounded secondaries are employed to transform the incoming utility-voltage to the lower potential used by the mining machines, generally three-phase 4160 V. At this level, pit distribution is carried on overhead lines, supported by wooden poles, to supply switchhouses located in benches near the particular piece of equipment. A switchhouse is a small portable (often skid-mounted) structure at the termination of an overhead line which contains disconnect

Jan 1, 1976

By Michael G. Zabetakis

The process of ?gasfreeing? has been defined3/ as "* * * the removal of oil and vapors from tanks, pipelines, and compartments to render such spaces safe for the intended work," Generally, part or all of a vessel is gasfreed for one of several reasons: Periodic cleaning; tank inspection or repairs; shipyard overhaul or major repairs; or change of cargo, Curing the gas- freeing, flammable or explosive4/ mixtures (mixtures through which a flame can propagate after ignition by an open flame, heated object, electrical charge, or other means) may be produced. These mixtures create an explosion hazard, as the pressures produced after their ignition are often great enough to completely demolish the vessel and kill all those aboard, This paper outlines a study by the Federal Bureau of Mines of the gas explosion hazards likely to be encountered while gasfreeing a vessel compartment. To better understand these hazards it will first be necessary to review the language used in gas- explosions work. This language is considered in the following sections. Inert gases such as carbon dioxide, nitrogen, water vapor, and others can be used to decrease the range of combustible-vapor concentrations in which flammable mixtures are formed. Sufficient quantities of such gases can often be added to cause a mixture that originally was flamable to become nonflammable. Unfortunately, the use of water vapor in this application is complicated by the fact that elevated temperatures are required to keep the water in the vapor state. In practice, it may be difficult to maintain these elevated temperatures throughout the space (such as a cargo tank) to be inerted for any length of time. Accordingly, where other inert gases are not available, it may be desirable to gasfree a Lank by using heated air. To do this, the combustible vapors should be flushed as quickly as possible from the space to be gasfreed. In a properly designed system, large tanks were gasfreed with a littlee as 6 volumes of air per volume of tank capacity.

Jan 1, 1961

By J. Douglas Causey

In 1985, at the request of the Bureau of Land Management, the U.S. Bureau of Mines studied a portion of the 110,000 acre Massacre Rim Wilderness Study Area (CA-020-1013). The area studied, containing 23,260 acres, is located in northwest Washoe County, Nevada, about 25 miles west of Vya adjoining the Charles Sheldon National Wildlife Refuge. Basalt caps older tuffaceous sedimentary rocks in an area that contains no claims or prospects. No mineral resources were identified during this investigation.

Jan 1, 1987

By Arthur L. Murray

"Oil-shale camps are peculiarly favored, in that before they are establishes it can be ascertained with a degree of certainty, that the life of the project is not limited. Unlike camps at metal mines, where the metal content of a given area is frequently an unknown quantity until after years of development, oil-shale camps should, from the outset, be planned and. built as permanent types of camps. Where this procedure is followed camps will be established which better serve the needs of the industry and the cost of their general care and upkeep will be less.Selection of camp or townsite.The site of the camp or town' whether on company property or not, should be selected with care. It should be separate if possible from the location of the plants of the company so as to be free from noise and fumes and so as to provide a change of environment for employees in going from their work to their homes.The principal features governing the site to be selected are as follows:Drainage. The general contour of the surrounding country should be such that drainage is away from the site. The camp or town should, if practical, be situated on higher ground than that in its immediate vicinity.Soil. The nature of the soil on which the camp or town is located may bear a decided relation to health. A porous, well underdrained top soil of at least four feet in depth insures dryness and facilities the placing of foundations and the laying of water mains and sewer pipes. Such a soil also is an advantage in growing trees, shrubs and grass plots, which are a decided adjunct to making the community attractive.Enviroment. The contiguous territory should afford no unwholesome sur¬roundings such as swamps Or accumulations of stagnant water.General Considerations. The water supply to be provided and the method of disposal of wastes influence to a certain extent the location of the camp or town-site. The means of supplying water, whether by gravity or by pupping, and the disposal of sewage, whether by outfall, system, sewage disposal system through septic tanks, broad irrigation or filter beds, or cesspools will govern the location of the site topographically in relation to source of water and point of disposal of sewage.* This article was prepared as part of the paper ""Use and Supply of Water for the Oil-Shale Industry"" by J. J. Jakowsky, to be published by the Department of Metallurgical Research, University of Utah, in cooperation with the United States Bureau of Mines."

Jul 1, 1921

By David Hoadley, Kenneth R. Maser, Ashok B. Boghani, James E. Billar, D. Randolph Berry, Mackenzie Burnett, Robert H. Trent

A.5 Conclusions and Recommendations The illustrative simulations in the previous section have demonstrated 1. Flexibility of the program to simulate a wide variety of configurations and cases. 2. Ability of the program to predict evacuation time within a small margin of error (5 percent -.n a case considered). 3. Usefulness of the program in making some of the evacuation decisions. The above leads to a conclusion that the computer program can provide a useful tool in evaluating mine evacuation in the event of a fire. At present the program can be used to make decisions regarding evacuation scheme improvement, while the scheme is being studied. However, significant software and hardware developments are

Jan 1, 1976

By Joseph Cervik, J. H. Perkins

The Bureau of Mines has conducted desorption work on fine coal particles at near atmospheric pressure. An apparatus has been developed that uses a capacitance manometer to measure desorption of methane from coal particles up to 2 inches in diameter and pressures up to 1,000 psi. This will make it possible to duplicate the desorption process as it occurs in its natural under- ground environment.

Aug 1, 1970

"The major thrust of this research is directed towards a better undstanding of the behavior of airborne dust particles in underground mine airways. Figure 61 shows a schematic of dust flow in mine airway. The work included development of a mathematical model of dust behavior in mine airways, experimental study of the behavior of dust clouds and comparison of computer model output and experimental results. Re-entraiment is a secondary source of dust in mine airways and factors affecting re-entrainment are being identified.Investigations have encompassed both experimental and theoretical research into the behavior of dust in mine airways. Experiments were performed in mine airways under both controlled and normal operating conditions (Figure 62). The controlled experiments included the documentation of the concentration and desposition patterns for two types of dust under three different velocities. Real-time dust concentration data were obtained using real-time aerosol monitors (RAM-1) (Figure 63).On the theoretical front, a convection-diffusion model of the dust flow phenomenon in mine airways was developed considering dominant mechanisms affecting dust transport and deposition in mine airways. Mechanisms modeled include turbulent and gravitational deposition, coagulation, and dispersion. Comparative analyses of results of the controlled experiments with the predictions of the mathematical model were carried out. In addition to the overall validity, the adequacy of the individual components of the model, such as deposition in the total and respirable range, and dispersion were examined in light of the experimental observations."

Nov 1, 1988

By L. H. Lange, F. F. Hintze

"Mineralogical Composition of Cyanite RockIn the group of minerals used in making this study, the cyanite is associated with quartz, mica, and feldspar in the schist. The amount of quartz is variable, but it is always an abundant mineral. Both large and small crystals of quartz occur in irregular masses, rarely ever showing crystal outline. Mica is of the clear and dark varieties the larger crystals being dark as a rule, and the finer crystals of light color, The present mineralogical composition of the mica is rather variable as most of the original biotite and muscovite have suffered alteration, and much secondary mica is present as a result of alteration of the original mica and other minerals present, especially the larger cyanite crystals. A large part of the mica now found in the ore is chlorite, with varying amounts of Jefferisite and others, especially sericite. These are in the form of aggregates, or felt-like intergrowths filling the spaces between the quartz, cyanile, and feldspar.The feldspar is plagioclase probably mostly albite. It is white, possesses good cleavage, and is one of the hard brittle minerals of the rock. It alters to kaolin, and sericite, and more or less of these alteration minerals are present within the feldspar crystals but not separated from them.The cyanite is of two varieties, distinguished by their colors as blue and white cyanite. The blue color varies in intensity, being a pronounced blue in some crystals and paler in shade in others. Some crystals have been seen which possess the blue color in one-half of their mass and are pure white or clear in the other half. The purity of the cyanite is probably not affected by the color, but it is difficult to detect the white cyanite in the ore by macroscopic examination, so that great care has to be exercised in the selection of the ore in the field."

Apr 1, 1931

By Lewis C. Karrick

In studying the destructive distillation or pyrolysis of oil shales, the primary consideration is to determine the effects of heat on the organic components of the shale. The impracticability of separating these organic components, collectively known as "kerogen", from the mineral matter with which they are associated renders the problem extremely complex. The behavior of the kerogan in the shale while undergoing the heating process is probably different from that of the same kerogen if it could be isolated and treated under similar temperature conditions, and in fact the results of actual distillations have shown that the physical properties of the mineral matter in the shale may be the cause of much variation in the products of retorting. It must be remembered that the inorganic .material of the shale is a heterogeneous mixture of minerals solidified into a very close-grained compact mass. This mineral mass has a thermal conductivity different from that of the kerogen, thus complicating the problem of even distribution of heat. Furthermore, the temperatures of dehydration of gypsum end some; hydrous silicates are included within the temperature range of the shale distillation, These minerals are frequently present in the shales; and the evolution of water vapors from them will affect the partial pressures of the hydrocarbon vapors evolved from the kerogen, probably tending toward, the improvement of the quality of the oil distillates. Carbonates and sulphides which are also frequently present begin to decompose within this range of temperature, and the gases produced from them may alter the chemical constitution of the oils produced from the kerogen.

Jan 1, 1922

"Correlatina Lung Crackle Usina Holographic lnterf erometryAli Afshari, MS, West Virginia University, 1989The Effect or Surfactants on Suppression of Non-Wettable ParticlesAli Alaboyun, MS, Mineral Engineering, The Pennsylvania State University, 1989Geochemical Characterization of Kerogem, ShaJes, and Coal .Refme ~ted with Allegheny Fonnationof Cases of Northern West VirginiaDick Andre, MS, West Virginia University, 1987Particle Concentrations in a Hazelton Inhalation ChamberShahram Bavani, MS, West Virginia University, 1985Use and Potential of Luer Holographic Interferometry and Subsidence Model Study of an Underground.Room and Pillar MineRichard Begley, MS, West Virginia University, 1984Development of a Mechanistic Model for Prediction of Subsidence in a Longwall MineRichard Begley, PhD, West Virginia University, 1990.Redesign of Micro-Orifice Unifonn Deposit ImpactorSteve Behm, MS, University of Minnesota, 1991A Fracture Mechanics Study of Crack Propagation Mechanism in Coal: The Mechanics of Fine FragmentFonnationZ. T. Bieniawski and R. Karl Zipf, Jr., Mining Engineering Department, The Pennsylvania State University,University Park, PA. Final Report, October 1, 1988A Mathematical Model for the Prediction of Ambient Dust Concentrations in Mine AtmospheresR. Bhaskar, MS, Mining Engineering and Operations Research, The Pennsylvania State University, 1984Spatial and Temporal Behavior of Dust in Mines-Theoretical and Experimental StudiesR. Bhaskar, PhD, Mining Engineering, The Pennsylvania State University, 1987Experimental Studies of Dispersion and Deposition of Fane Particles in a Wind Tunnel and Mine AirwayKlaus Bode, MS, Mining Engineering, The Pennsylvania State University, 1991Perf'onnance of the High Yield Technology PM - 100 - Particle 11ux MonitorRobert Caldow, MS, University of Minnesota, 1987Development of Improved Methods for Monitoring and Control of Diesel Particulate in an Underground CoalMineD. H. Carlson, B. C. Cornilsen, P. L. Loyselk, X. Shan and J. H. Johnson, Michigan Technological University,Houghton, Ml. Final Report, June 15, 1991"

Mar 1, 1992

Crosson and Peters treat the errors that result in miner location due to errors in the overburden earth model used for computing location. A parallel effort by J. Powell of PMSRC is discussed here, where the location method used is that of the Westinghouse location program - "Miner". This location program was tested by Powell by using arrival times generated from the overburden earth model of Table l* rounded to the nearest millisecond. Location computations were then made using 3 geophones at a time. The average location is tabulated for all geophone triplets except when 3 geophones are in line. Geophone arrays were as shown in Tables 2 and 3. The manner in which the test was done is illustrated in Figure 1. I. SUMMARY OF RESULTS The arrival time differences, based on the Table 1 earth model, together with geophone locations based on the array geometries of Tables 2 and 3, were entered into the computer, together with a stated depth of 700 feet and an estimated overburden seismic velocity of 10,000 feet per second. These parameter values were processed by the location program - "Miner". Figure 2 illustrates the interpretation of the plots and data. The tabular data and plots of Table 4 and Figures 3, 4, and 5 illustrate the location error results obtained. These plots indicate that for sources within the array, the errors are considerably less than the measured errors obtained during field tests of the present location system. The possible reasons for this discrepancy are noted in Part Eight (Earth Models).

Jan 1, 1974