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By Thomas E. Lobb, Harry C. Verakis

Significant progress has been made in the reduction of serious injuries and fatalities resulting from mine blasting operations. Despite the progress, injuries and fatalities continue to occur. A leading cause of injuries and fatalities from blasting continues to be inadequate blast area security. Even though significant improvements in technology have been made, insuring adequate blast area security remains a challenge and requires constant vigilance. The advances in technology have created safer blasting products and have improved productivity and economics by enabling large, more efficient and effective blasts. However, as blasts grow larger in size, the complexity of adequately securing the blast area increases even more. Periodically the basic fundamentals involved in blasting safety should be reviewed, particularly for securing a blast site regardless of the size of the planned blast. Factors such as flyrock and toxic fumes must be taken into account to insure the safety of persons and property from the results of a blast. This paper examines the factors related to injuries due to inadequate blasting shelters and blast area security, and identifies mitigation techniques. The key concepts are: (a) accurate determination of the bounds of the blast area, (b) clearing employees from the blast area, (c) effective access control, (d) use of adequate blasting shelters, (e) efficient communications, and (f) training. Fundamentals are reviewed with an emphasis on analyzing task elements and identifying root causes for selected blasting accidents. Mitigating techniques are presented along with discussions and examples.

By C. A. Herbert

The mine of the Alpha Portland Cement ..Co., Iroaton, Ohio, ..working in. a. bed of limestone 96 feet thick at a depth of approximately 510 feet below the surface, has established a won¬ derful safety record, having operated 6 years—frcra September 21, 1926,. to September 21, 1932 - without a lost-time accident. This mine, with 61 to 86 employees (average 68) and daily output of 1,000 to 1,200 tons of limestone, operated 1,041 days during the 6-year period, or the equivalent of 578,894 man-hours of exposure. ...... ... . Immediately above the limestone is a 20-foot .bed of hard..sandstone.. At present about 10 feet of limestone is left up as. a roof and.about. 42 feet is being extracted. Of the lower portion of the bed it is believed that about. 25 feet. ..immediately below . the .present workings is suitable for cement and will be extracted later. The mine workings are reached by two rectangular concrete shafts, one a 2-compartment hoisting shaft and the other a 2-compartment air and escape shaft- In the latter shaft one compartment is used as an airway and the other, as a cage compartment fo.r a man and material cage. .. . - . The tipples at both the air shaft: and. hoisting shaft are-of steel. The.ground landings at both shafts are fenced in with hand-operated gates in front of the cage compartments.- The two shafts and the crushing plant, which .is.a part of the hoisting shaft-tipple structure, are adjacent to the mill buildings. The rock is hoisted on self-dumping cages in 4 ton capacity, end-gate, steel cars. An electric hoist with automatic overwind device is used at both the main shaft and air shaft. The controls for the main hoist are in the tipple where the engineman is stationed and from which point he has an unobstructed view of both the ground, landing and the cage coming into the dump.

Jan 1, 1933

By R. V. Ramani, R. Stefanko, G. W. Luxbacher

The Federal Coal Mine Health and Safety Act of 1969 has dictated major changes in mine ventilation with regard to both air quantity and quality. Requirements have also been placed on the ventilation of beltlines, gob and face areas, and air velocities on trolley haulage roads are limited. Escapeways, separate from trolley haulage roads and on an intake split of air, must be maintained continuous to the surface. These and other similar requirements have not only precipitated several modifications to existing ventilation systems but also have greatly increased the complexities of new mine ventilation planning. It is apparent that the use of computers in ventilation system analysis and design is a necessity. SUMMARY Although computer oriented analysis of mine ventilation systems was introduced over two decades ago, it has yet to receive widespread acceptance in the United States. Central to this problem is the fact that, while many computer programs for network analysis have been developed, no attention has been paid to the development of computer input data. Consequently, without this foundation, program applications have been infrequent. This thesis has directly attacked this problem and has presented all pertinent information basic to the development of good computer input data. The areas that were covered include quantity measurement, pressure measurement, fan testing, survey data balancing, and the development of a network schematic from the ventilation survey results. These discussions on data collection and the corresponding reduction to computer coding have been illustrated by an application of a ventilation simulation program to an existing mine in Southwestern Pennsylvania. The use of a ventilation

Jan 1, 1977

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

C 6 Automatic Elevator Control Systems An automatic elevator control system, consisting of position sensing devices and a control unit, can be used to control an emergency mine hoist. While automatic elevator control systems are assembled from standard components, they are typically custom designed to suit a given customer's application. Various manufacturers contacted indicated that the price range, less installation, for a simple two-stop control system begins at approximately $2500 and can increase depending upon the type of components used, shaft depth, the type of mechanical drive used, and the maximum operating speed A partial list of elevator control manufacturers follows. They should be contacted for further details. Marshall Elevator Company Pittsburgh, P A 412 -431 -1340 Armor Elevator Company, Inc. Louisville, KY 502-361 -7181

Jan 1, 1976

By W. C. Smith

The U.S. Bureau of Mines examined previous research on rib stability in an effort to develop a practical approach to understanding, characterizing, and controlling weak rib conditions in underground coal mines. Because success in stabilizing ribs depends on a basic knowledge of how weak ribs behave, the report reviews the mechanics of rib failure and the relationship of coal mine geology and pillar constraint to rib instability. Strategies for choosing an effective method of rib support are considered, and various rib support methods are discussed. Finally, the report documents techniques for monitoring ribs and use of models to assess rib stability; such monitoring and modeling can also help determine the most effective method for roof support.

Jan 1, 1992

By W. P. Rumancik, C. P. Lazzara, A. C. Smith

The United States Bureau of Mines (USBM) developed SPONCOM to aid in the assessment of the spontaneous combustion risk of an underground mining operation. A prior knowledge of the spontaneous combustion risk of the coal and factors that increase that risk can be useful in the planning and development of proactive monitoring, ventilation, and prevention plans for the mining operation. Interactive data input screens prompt the user for information about the coal's chemical and physical properties, the geologic and mining conditions encountered in the mining of the coal, and the mining practices employed. During the input process, 'expand' screens provide the user with specific information on each input parameter. This information includes a description of the parameter and its effect on the overall spontaneous combustion risk. The program logic determines the coal's relative spontaneous combustion potential, based on the coal's proximate and ultimate analyses, and heating value. The program then evaluates the impact of the coal properties, geologic and mining conditions, and mining practices on the spontaneous combustion risk of the mining operation. The program output provides details on each factor that increases the risk of spontaneous combustion.

By M. K. Larson, J. K. Whyatt, F. M. Jenkins

The U.S. Bureau of Mines conducted an overcore stress measurement on the 5300 level of the Lucky Friday Mine, Mullan, ID, to investigate the stress regime around an experimental stope in a rock-burst-prone mine. The result indicated a stress field with unexpected magnitude and orientation [F . 135 MPa (19,600 psi) oriented S 80E1W]. An unusual amount of rock-burst activity was encountered during subsequent excavation. A careful review of the overcore data suggested the overcore strain measurements were valid. Moreover, concentrated rock-burst activity suggested that the measured stress field did exist, but was localized and therefore did not represent the far-field in situ stress field.

Jan 1, 1995

By Elaine T. Cullen

Safety training materials appropriate for specific underground noncoal operations in the United States are often outdated or nonexistent. The Spokane Research Laboratory (SRL) of the National Institute for Occupational Safety and H ealth has developed several new training tools, including three videos on common underground activities, software that will allow trainers to create a virtual training mine using their own mine map, and toolbox training materials. SRL is working closely with industry in the development of these tools. Teams of safety professionals are involved in the early stages, and actual mines and miners are involved throughout the production phase. This presentation describes the development process and results of SRL’s safety training projects.

By James J. Bryja, Thomas M. Barczak, Dennis R. Dolinar, Joe Bower, Thomas P. Mucha

Maintaining ground stability in the gate roads, particularly the tailgate, has always been critical to the success of longwall mining, both in terms of safety and productivity. Several new support technologies have been developed in recent years to replace conventional wood and concrete cribbing for secondary roof support. Since their performance characteristics are unique, the best practices that have been developed with conventional wood cribbing may not be applicable for these alternative support technologies. Therefore, with so many options to consider and the importance of achieving adequate ground control at minimal cost, the trial and error approach to longwall gate road support is no longer prudent. This paper discusses a design methodology for standing secondary tailgate supports. This design technique requires in-mine measurements of tailgate support loading and convergence to establish a tailgate ground, reaction behavior based on the support and strata interaction. The methodology uses the performance characteristics generated in the National Institute of Occupational Safety and Health (MOSH) Mine Roof Simulator (MRS) to match the stiffness and load characteristics of various supports to the measured ground reaction behavior. It can be used to determine the appropriate -- application of alternative roof support systems or to design in- mine trials such that a fair and equitable comparison of different support systems can be made. A case study if the methodology at a western Pennsylvania mine site is presented in the paper, including a comparison of four alternative support technologies to conventional wood and concrete cribbing historically used at this particular mine.

The twelve latexes listed in Table XI penetrated A horizon soil as shown by elution through a laboratory soil column and gave good sealing efficiency. See details in Table XII. High elution through laboratory soil columns of 4 to 6 inches depth is desirable because it predicts penetration of latex to a greater depth in the field. No definite correlation was evident between penetrating ability and particle size, surface tension, or pH. Most of the materials, however, were characterized by low surface tensions in the 36 to 53 dynes/cm range while particle sizes were usually in the intermediate range of about 1500 to 2500 Å. Naugatex J-3471 (a highly crosslinked styrene-butadiene copolymer) was the most promising of this group for stability, penetrating ability; and sealant efficiency. It also showed utility with [B] profile soil. Many of the other latexes tested in this investigation showed good sealing efficiency but were judged unsatisfactory because they gave low penetration or formed surface films with & horizon top soil. In general, latexes containing cationic surfactants were not satisfactory because they formed a heavy surface film. This is due to neutralization of the positive latex charge by the negatively charged soil particles.

Jan 1, 1972

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

MINE PROTOTYPE The prototype chosen for application demonstration is from Kingery (1960). The mine and the ventilation plan is presented in Figure 11. A new coal mine is projected with entrance by slope 1,500 feet long. Nine train entries will be standard for development, five as intake and four as return. One return shaft is planned near the slope bottom. The slope will have an area of 150 square feet and a perimeter of 55 feet. The return shaft will be circular with a diameter of 18 feet and will be 500 feet deep. Two hundred feet of the shaft and 500 feet of the slope will be concrete lined. Will it be possible to operate five units per shift with amount of air at each unit not less than 25,000 cfm? Additionally, a shop at the slope bottom will require 10,000 cfm. The problem is completely worked out using standard ventilation formulas and simple manual calculations in the above reference and is reproduced here in Appendix II for ready reference. APPLICATION In this manual, four different applications of the PSU/MVS are outlined. An article by Stefanko et al (1972), outlines how one can move from a mine map to a network for the generation of computer input. Attention is drawn to Figure 12, which is the network line diagram of the mine ventilation system in Figure 11. Note that every roadway junction has been numbered. The dotted lines represent leakage paths and the letter 'R' on a branch denotes that the split is regulated for the quantity shown. For example, there is a leakage

Jan 1, 1975

By Launa Mallett

This training material focuses on the content of emergency warning messages. Research has shown that when an emergency occurs, people often do not get the information they need for the purpose of taking appropriate action. This safety talk presents a procedure, using mental cues that can be used by senders and receivers of emergency warnings.

Jan 1, 1999

By D. O. Kennedy

THIS CHAPTER on minor nonmetals covers greensand, meerschaum, mineral wool, and wollastonite. Mineral wool was by far the most valuable material among these minor nonmetals reported in the United States in 1956. GREENSAND Output of greensand (glauconite) declined in 1956. The Kaylorite Corp., Dunkirk, Md., and the Inversand Co., Sewell, N. J., were the only firms that reported production of this commodity. Output came from open pits in Calvert County, Md., and Gloucester County, N.J.

Jan 1, 1958

Lower the respirable dust exposure of longwall shearer operators by use of a modified head to tail cutting sequence. Approach Modify the cutting sequence of double-drum shearer operations cutting unidirectionally head to tail, so that the tailgate drum is used to mine the entire coal face except when cutting out at the head. This approach would place the primary dust generating source, the cutting action of the drum, on the return air side of both shearer operators. How It Works Currently, 75% of the double-drum shearers in operation employ a unidirectional cutting sequence. On half of these operations, the primary cut is taken as the shearer travels from the headgate to tailgate ends of the face, with roof support to be advanced on the intake air side of the shearer. Typically, the leading (tailgate) drum is taking a full cut during the head to tail pass and the trailing (headgate) drum is cutting bottom coal. In this mode of operation, the dust generated by the trailing (headgate) drum can spread out into the walkway, and increase the respirable dust exposure of both head and taildrum operators. As an alternative, if the trailing drum is "free wheeling" or cutting minimal coal during the head to tail cut, and bottom coal taken by the tailgate drum during the tail to head clean-up pass, both operators are able to work on the intake air side of the primary dust generating source (drum) except when cutting out at the head. This modified cutting sequence would save wear on the conveyor and help to eliminate overloads, as well as reduce the respirable dust exposure of both shearer operators. This modifcation is only applicable to long-wail operations currently cutting unidirectional head to tail, and to those operations where this unidirectional cut would not produce operating constraints.

Jan 1, 1981

Provide the technology to remotely reset circuit breakers on continuous mining machines used in extended cuts.

Jan 1, 1994

By Lloyd A. Morley, Alan M. Christman

General A review of the literature has revealed important areas which should be investigated during the field work. Of the utmost importance is the safety of mine personnel. Should a phase-to-ground fault occur on a shovel or other piece of equipment, current may return to the substation through the machine's contact surface with the mine floor, thereby raising the frame above ground potential and posing a shock hazard to anyone who touches the equipment. If the frame-to-earth resistance is very low, then no dangerous potentials will be developed, and a basis for elimination of the ground conductors from trailing cables could be postulated. However, should the contact resistance be high, then lethal voltages could be present on the machine frame. In this instance, low-resistance ground conductors in the trailing cable would be a necessity. Therefore, field tests should include measurements of the earth resistance of electrically operated portable or mobile mining equipment such as shovels, draglines, and drills. When the electrical distribution system is subject to lightning discharges, the grounding grid must safely carry to earth and dissipate enormous current surges. It is essential that the grounding grid have a low value of earth resistance, because any potential developed across the grounding grid as a result of current flow will appear on the frames of all machinery connected to the grid. Thus, an earth resistance

Jan 1, 1976

By Kenneth P. Klouse

The current rulemaking on mine illumination makes it necessary for mine personnel to have an understanding of the behavior of light. They must be able to understand many terms that are new to the industry and must be familiar with the use of various types of photometers. With this knowledge, the enforcement criteria for mines can be understood and compliance can be maintained.

Jan 1, 1976

By James D. Sisler

Location and Age The main bituminous coal field of Pennsylvania lies in approximately twenty counties west of the mountain area which extends in a northeast southwest direction through the central part of the Commonwealth. The coal fields lie in a dissected peneplain, still in the youthful stage of erosion There are numerous V shaped valleys in the bituminous fields and the tributaries of the larger streams have rather steep gradients The main streams flow in rather narrow valleys with comparatively small flood plains. The coal beds of Pennsylvania are of Carboniferous age, and are confined to two systems, the Permain and the Pennsylvanian The latter system is divided into an upper or Pittsburgh series and a lower of Pottsville series The Peimain system is divided into an upper and lower series The Pottsville series of the Pennsylvanian is represented in western Pennsylvania by the Upper Pottsville only The upper or Pittsburgh series of the Pennsylvanian is represented by the Monongahela, Couemaugh, and Allegheny groups Geologic Structure. The rocks of the bituminous coal fields are folded into many anti clines and synclines extending in a general northeast direction across the western part of Pennsylvania The intensity of this folding in creases toward the mountain region West of Chestnut Ridge, which is in Fayette, Westmoreland, and Indiana counties, the folding is minor, and the coal beds have low dips East of Chestnut Ridge, v here folding is stronger, the basins are wider and the coal beds rise steeply on the flanks of the anticlines Geology. The bituminous coals of Pennsylvania are associated with shale, sandstone, clay, and limestone Each group has different proportions of these deposits, and the proportions vary at different localities within the same group.

Jan 1, 1928

By Kenneth L. Cashdollar

This paper is an overview of and introduction to the subject of dust explosions. The purpose is to provide information on the explosibility and ignitability properties of dust clouds that can be used to improve safety in industries that generate, process, use, or transport combustible dusts. The requirements for a dust explosion are: a combustible dust, dispersed in air, a concentration above the flammable limit, the presence of a sufficiently energetic ignition source, and some confinement. An explosion of a fuel in air involves the rapid oxidation of combustible material, leading to a rapid increase in temperature and pressure. The violence of an explosion is related to the rate of energy release due to chemical reactions relative to the degree of confinement and heat losses. The combustion properties of a dust depend on its chemical and physical characteristics, especially its particle size distribution. In this paper, the explosion characteristics of combustible dusts will be compared and contrasted with those of flammable gases using methane as an example. These characteristics include minimum explosible concentration, maximum explosion pressure, maximum rate of pressure rise, limiting oxygen concentration, ignition temperature, and amount of inert dust necessary to prevent flame propagation. The parameters considered include the effects of dust volatility, dust particle size, turbulence, initial pressure, initial temperature, and oxygen concentration. Both carbonaceous and metal dusts will be used as examples. The goal of this research is to better understand the fundamental aspects of dust explosions.

By Michael S. Wieland

The work-principle method was developed for theoretically resolving toxic fumes from non-ideal charge formulations. The whole description of a wanted process refers to macroscopic changes resulting from removing and imposing constraints that work one at a time to chronologically render trajectory terminal (key) states. The trajectory resolution utilizes a thermodynamic quasi-potential or negative work function, and numeric results require some appropriate standard thermodynamic (equilibrium) reaction code TDRC. The underlying method is unable to restrict reactions, tailor the work output or resolve states within the trajectory transitions, so the trajectory terminology is used somewhat figuratively. The work-principle model has the working fluid (reaction material) interacting with a tremendous reservoir (chamber air and walls), while forecasting the work performed upon a mechanical agent. Within the underground test chamber, the widening fume zone undergoes a decline in temperature, a reduction in reaction rates, resulting in out-of- equilibrium circumstances at the Q*-point, representing the measurement state. Rather than coping with the hard issues of non-equilibrium, the toxic fumes are resolved numerically for the Z-point, rendered by a zero-net- interaction energy constraint. Though other techniques require complex equation-of-state EOS for the whole trajectory, the work-principle formulation eludes the issue, requiring an EOS that works just for the terminal-state. Under the circumstances, the Z-state is reconcilable with the ideal-gas domain, and relevant TDRC results yield the restricted state in a numerical way for different charge formulations. The work principle makes it hard to remedy or to tamper with the resulting Z-point fumes: non-macroscopic trajectory readjustment is forsaken, terminal states are results rather than stipulations, and resetting the EOS formula constants would be ineffectual. Though the non-equilibrium portion remains unresolved, it is noteworthy that the work principle rigidly fixes the Z-state, thereby reducing the uncertainty for rendering reaction-rate models characterizing the non-equilibrium Z-Q* transition. Though more refinements are needed, some Z-point fume results are included to illustrate the threshold (minimum) resolving capacity of the work- principle formulation.