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By Wilbur I. Duvall

In this report, the Bureau of Mines presents a theoretical solution for the stresses and displacements in an infinite elastic plate containing a circular hole the boundary of which is loaded by applied radial stresses over four separated arcs. The problem solved is a two-dimensional approximation of the stresses and displacements developed by a large tunnel-boring machine anchored in a circular tunnel. Analysis of the solution shows that the tangential tensile stresses induced on the boundary of the circular opening can be minimized in the roof and maximized in the floor of the opening by proper spacing and loading of the four arcs.

Jan 1, 1967

Underground and strip mining (6,7) produce different hydrologic environments. Many underground mines are below the zone that is completely saturated with water and the mine openings may cause new and continuous contact between sulfurous material and water which flows from the saturated zone to the workings. Strip mines are usually above the zone of continuous saturation and contact between sulfurous material and water is generally restricted to periods of precipitation. A full appreciation of the problem of water pollution caused by drainage from deep mines requires a basic understanding of occurrences and movement of water in the ground and the modes of ground water entrance into mining areas.

Jan 1, 1970

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

By Martyn F. Roetter

The work of the operational communication systems' group dealt with a range of communication needs and functions within mines, primarily along haulageways, to and within sections up to the working face itself, and in mine shafts. A mixture of communication techniques and hardware is needed to satisfy this variety of communication needs within the differing environments encountered in U.S. mines. Substantial progress, both experimental and theoretical, has been made in recent years towards developing alternative communication systems suitable for use in mines which are based on "guided" waves, including wire-less (waveguide-like propagation in mine tunnels) and wire-based systems (leaky coaxial cables or wires) . Major priorities identified for further work needed to confirm (or deny) the applicability, and refine the operational specifications of promising communication systems for mine use include: Short-Term Projects o Cost/performance analyses of promising leaky coaxial cable and UHF radio communication systems which require further data from: - Experimental investigation under U.S. mine conditions of the performance of potentially applicable leaky coaxial cable communication systems developed in Europe (France, Belgium, and the U.K). - Cost estimates on these coaxial cable communication systems. - Measurements of UHF radio propagation in low-coal mines. - Investigation of the influence of obstacles (e.g. shuttle cars and section machinery) in the entries on UHF radio propagation in mines. o Investigation of the problems of transmitter and receiver coupling and termination matching associated with the two-way propagation of low frequency radio waves in hoist shafts.

Jan 1, 1973

By Lloyd A. Morley

This report details the continuation of mine power systems transient research under USBM Grant G0155003. The purpose of the work, which commenced under Grant G0133077, is the elimination of safety hazards created by transients" and the objective is to provide knowledge about transients existing in a-c and d-c coal mine power systems. The report chapters cover theoretical background, instrumentation, and experimental investigations. The instrumentation discussion scans measurement problems and considerations plus the development of a low-cast peak-detector. Transient data from in-mine measurements are presented and include high-voltage distribution and d-c trolley systems. Extremely unique field exercises are described involving actual power equipment connected on the surface to duplicate typical underground coal mine system arrangements. Here, transients on high-voltage distribution resulting from vacuum circuit breaker operations could be observed under controlled conditions, and work centered around how surge capacitors effect transients. Using the in-mine and staged transient data, specific conclusions and recommendations are made with emphasis on high-voltage distribution.

Jan 1, 1977

Improve underground mine roof bolt support systems by alleviating problems associated with certain ground support systems currently being used. Approach Convert a passive resin-grouted roof bolt system into a uniform, tensionable roof bolting system. Background Resin-grouted roof bolts are one of the most common forms of ground support in U.S. underground coal mines. These support systems can be installed with a full-column of grout and be loaded with subsequent roof movements after installation. This is called a "passive" support system. An alternative to the passive support system is the mechanically-anchored, tensioned roof bolt system. This system is installed with resin grout. This system is designed to load or tension the support during installation by using a mechanical anchor, coupling, or threaded nut after the resin has properly cured. It is called an "active" support system and is used extensively for improved strata control in a laminated geologic deposition or in difficult ground conditions. To ensure that active bolts have been properly installed, the bolt loads must be checked by using a torque wrench or other suitable equipment. Unfortunately, this practice presents potential safety hazards and has limited accuracy. Laboratory and field experiments also reveal that the torque-to-tension ratio developed on active support systems can vary by 50% from bolt-to-bolt. Variations in bolt load installations can induce stress concentrations and lead to roof degradation or failure.

Jan 1, 1991

By Howard D. Jacobs

A bulk sample of oxidized taconite taken from the western Mesabi Range was evaluated by the Bureau of Mines using the Bureau-developed selective flocculation-desliming-cationic (or anionic) flotation process. The raw ore sample containing 32.3 pct Fe was treated by both cationic and anionic flotation. Using the cationic system the concentrates averaged. 37.2 wt-pct of the feed and contained 62.8 pct Fe and 4.7 pet Si02 with an iron recovery of 72.3 pet. With the anionic system, concentrates averaged 37.7 wt-pet of the feed and contained 63.0 pct Fe and 5.3 pct 8i02 with an iron recovery of 73.5 pct. A comparison of reagent costs showed that the cationic process cost 144.1 cents per long ton of crude ore and the anionic process 178.7 cents per long ton of crude ore. Reclaimed water comprised 86 pct of the total water requirement for anionic flotation and 88 pct for cationic flotation. The ore used in this study was one of three samples representing about 3.25 billion tons of oxidized taconite containing from 32 to 36 pct feed iron. Previous study had indicated that selective flocculation-desliming-cationic flotation would produce concentrates from the other two samples of 61.7 pct Fe and 5.1 pct Si02 at 67-pct Fe recovery, and 63.5 pct Fe and 4.3 pet Si02 at 8S-pct Fe recovery. By developing a successful treatment for these ores, the Bureau has insured the availability of technology for processing an amount of raw iron ore which, by itself, would supply U.S iron needs for 50 to 75 years at expected consumption rates.

Jan 1, 1981

By Kevin Michael, David C. Byrne

In previous issue of Spectrum (October 1999, 16/4), a system of measuring the attenuation provided by insert-type hearing protectors was described, That report described experiences using the FitCheck (Michael & Associates, Inc.) system in a pilot project involving the steel industry during 1998.[ ]

By Jozef S. Stachulak

In This Chapter [Ore pass dust control Drill dust control Blasting dust control Conveyor belt dust control Transfer point and crusher dust control Roadheader dust control and How much ventilation air to use] This chapter discusses respirable dust control in underground hard-rock mines. These mines use a wide variety of extraction methods, but they have many common dust sources and dust control needs. Ore passes, drills, blasting, conveyor belts, transfer points, crushers, and load-haul-dump operations can be major sources of dust. Roadheaders, which are sometimes used in hard-rock mines, produce dust in large quantities. For the most part, dust in hard-rock mines is controlled with ventilation air, water sprays, and dust collectors. It is also important to prevent dust from getting into the air in the first place. Good dust control practices will reduce overall mine ventilation requirements. [Lack of maintenance is the main source of dust problems in hard-rock mines according to Rodgers [1974], who conducted a dust survey of hard-rock mines several decades ago. Rodgers found that spray systems had clogged sprays, dust enclosures had improperly fitted skirts, and ductwork was plugged and had leaks. Today’s mines have better maintenance programs (we think), but when dust levels are high, maintenance is still the first topic to address.] The Mining Association of Canada [MAC 1980] and Knight [1980] provide good general information about hard-rock dust control. For conveyor belt dust control, Goldbeck and Marti [1996] and Swinderman et al. [1997] are valuable sources of information.

Jan 6, 2003

By Edward A. Barrett, Roberta A. Calhoun

Introduction This Instructor’s Copy contains most of the materials trainers will need in order to use Drill Rig Incident (DRI). It includes suggestions for using the exercise, performance objectives for the training, master answer sheets, a scoring key, and a set of discussion notes that provides additional subject information. Four appendices are also included. Appendix A is the complete exercise problem booklet. It may be reproduced so that every person in the training class has one. Appendix B contains answer sheet blanks. The blanks are furnished if you choose to have the invisible ink answers that appear in appendix C printed on them at your location.3 Answer sheets are consumable. One is needed for each group of three to five persons who work the exercise together. An alternative is for each individual trainee to have his/her own answer sheet. Appendix D contains the 24-question pretest / posttest that was used in the field evaluation of the DRI exercise. Acknowledgment The authors thank Linda J. McWilliams, Statistician, NIOSH Pittsburgh Research Laboratory, for her assistance in analyzing the experimental data in this document.

Jan 2, 2005

By Seymour Wasserman

To develop noise control designs for secondary crushers in Taconite plants. Taken into consideration: 1. Acoustical criteria 2. Day-to-day operational considerations and maintenance accessibility 3. Materials of construction 4. Adaptability of design to other Taconite plants having crushers 5. Cost of noise control treatment.

Jan 1, 1977

Produce an annotated bibliography to serve as a comprehensive source of published information available on the use of soil amendments in coal mine reclamation and the characterization of coal mine soils. The Problem There is a substantial amount of information available tin coal mine reclamation and revegetation, particularly on the use of soil amendments to ameliorate site conditions and aid vegetation establishment, growth development, and productivity. Additionally, site characterizations based on chemical, physical, and mineralogical properties have been thoroughly researched. This information, however, is widely disseminated throughout various professional and scientific journals, State and Federal documents, proceedings of conferences, theses, and other technical writings. A critical need exists for a comprehensive and up-to-date summary of published information concerning the uses, methodologies, and types of soil amendments that arc necessary for reclamation success.

Jan 1, 1991

By J. R. Thoenen

This circular is part IV of the third paper (entitled "Sand and Gravel Excavation") of a series summarizing the technical problems involved in the production and preparation of sand and gravel. Part I discussed the use of power shovels, draglines, and excavator cranes; part II discussed the use of power scrapers, slackline cableway excavators and hydraulic monitors; and part III discussed the use of hydraulic, clamshell, ladder, and dipper dredges. This circular discusses haulage equipment in general, particularly the use of industrial cars with locomotives or hoists as the motive power. Part V, to follow, will discuss the use of other types of haulage equipment.

Oct 1, 1935

By T. L. Joseph

"In the January 3 issue of Iron Trade Review, Sweetser2, in referring to the problem of coke combustibility, points out that, ""Someone should formulate a rule for the rate of flow of coke through the zone of coke combustion that now appears to be confined to a comparatively restricted volume in front of the tuyeres,"" In formulating such a rule it is necessary to distinguish clearly between combustibility, a property of the fuel, and rate of combustion, which is determined by the rate at which air is supplied to the fuel bed. The rate of carbon gasified at the tuyeres of a blast furnace is independent of coke combusti-bility. A fast-burning coke will burn in a more restricted volume than a slow-burning coke, but both types of fuel will be consumed at rates determined by the supply of oxygen,A number of the definitions of combustibility that have appeared in technical literature relate more closely to rate of combustion than to combustibility. Perrott and Kinney) have correctly defined it as follows: ""Combustibility of coke from the standpoint of its use in, the blast furnace is inversely proportional to the mean rate of gasification per unit volume of the combustion zone, assuming other factors remain constant,"" Combustibility of coke refers therefore to those properties that determine the size or extent of the combustion zone. Relative differences in these properties can be measured by the depth of the fuel bed required to convert oxygen from the air into carbon monoxide."

May 1, 1924

"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

To develop a business case that promotes adoption of noise controls by reducing barriers to industry acceptance and enhancing drivers that foster their implementation. Background Over 75% of the U.S. mining workforce is exposed to hazardous noise, putting them at risk of noise-induced hearing loss (NIHL). Consequently, coal miners suffer high rates of hearing impairment that increase to 70%-90% by retirement age. To address the noise problem for coal miners, researchers from the National Institute for Occupational Safety and Health (NIOSH) first determined that the continuous mining machine (CMM) ranked first among machines associated with reported coal noise overexposures. Further studies found that most CMM noise is generated by three component systems on the machine: dust collection, cutting, and conveying. Of these systems, the on-board chain conveyor was found to be a dominant noise source. Noise generated by the conveying system was addressed through the development of a urethane-coated flight bar chain. The coated chain, shown in Figure 1, has demonstrated an 8-hour time-weighted average (TWA) reduction of operator exposure by 3 dB(A). It has since been accepted by the Mine Safety and Health Administration (MSHA) as a "technologically achievable" noise control for CMM operators who are exposed to noise that exceeds the MSHA permissible exposure level. Having demonstrated the noise reduction performance of the coated chain, NIOSH has assembled information into a business case that can be used by operations considering adopting the chain at their worksite.

Dec 1, 2009

By R. V. Ramani, C. B. Manula, A. Owili-Eger

This report was prepared by The Pennsylvania State University under USBM Contract No. G0111808. The contract was initiated under the Coal Mine Health and Safety Program. It was administered under the technical direction of DMRC, with Mr. G. R. Schottler acting as the technical project officer. Mr. J. A. Herickes was the contract administrator for the Bureau of Mines. These applications were developed initially as a part of the instructional material for the course Mng 422, "Mine Ventilation and Air Conditioning" at the Department of Mineral Engineering, The Pennsylvania State University. This ventilation simulator was developed under contract from the Department of Environmental Resources, formerly the Department of Mines and Mineral Industries, Commonwealth of Pennsylvania.

Jan 1, 1975

By Lloyd A. Morley, Robert Stefanko

This report was prepared by The Pennsylvania State University, College of Earth and Mineral Sciences, ' Department of Mineral Engineering, University Park, Pennsylvania, under USBM Grant No. GO-133077. The grant was initiated under the Coal Mine Health and Safety Research Program. It was administered under the technical direction of the Pittsburgh Mining and Safety Research Center with Mr. G. J. Conroy acting as the technical project officer. Mr. J. A. Herickes was the grant administrator for the Bureau of Mines. This report is a summary of the work recently completed as part of this grant during the period 19 June, 1973 to 17 June, 1975. This report was submitted by the authors on 18 July, 1974. This technical report has been reviewed and approved.

Jan 1, 1974

By L. H. Duschak

"This paper is based on the results of work conducted of the bureau's experiment station at Berkeley, Calif., in connection with the investigation of properties and methods of utilizing Western magnesite. The experiments described herein were made under the supervision of the writer, by W. C. Riddell and E. H. Delius, of the station's staff.In calcining magnesite for the production of magnesium oxide to be used in the preparation of oxychloride cement, the calcium carbonate present in the original rock may remain unchanged or appear in the finished product, either as CaO, or in combination with SiO2, A12O3, etc. As there is reason to believe that free CaO may have an effect on the behavior of caustic magnesia in the cement reaction, it is desirable to have a method for the determination of the relatively small amounts of free CO in the presence of a large quantity of MgO.The extraction of the free CaO with water free from CO2 at once suggests itself as a possible method. The solubilities of Ca(OH2)2 and Mg(OH)2. are given by Seidell in his book an ""Solubility of Inorganic and Organic Compounds."" (2nd Edition, 1919) as follows:"

Jun 1, 1920

By S. L. Payne, E. F. Foerster, C. W. Schultz, G. R. Zellars

The vapor pressure of copper in a series of liquid copper - nickel alloys was determined by the carrier gas method . The activity and activity coefficient of copper were calculated over the entire range of alloy composition . These data show a slight positive deviation from ideal behavior . The activity coefficient of copper was highest ( 2.10 ) at 0.05 mole fraction copper and approached unity at concentrations above 0.85 mole fraction copper . The results for nickel were calculated from the copper data by the graphical integration of the Gibbs - Duhem equation .

Jan 1, 1964