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Reduce shaft sinking costs and workers exposure to mechanical hazards, drill dust, blast dangers, and fumes. Approach Replace drilling and blasting by using a large, cab-mounted impact breaker suspended from the bottom work deck of the galloway. How It Works The pneumatically actuated impact breaker is positioned by an articulated boom con-trolled from an operators cab. The breaker delivers 2,000 ft-lb blows that fragment the rock at the shaft bottom. Mucking is accomplished by a backhoe bucket on an articulated boom mounted on the cab. See photograph. The mucked material can be removed either by dumping into a previously drilled borehole or by being lifted out in a muck bucket as shown in the drawing. Positioning of the breaker, rotating the cab around its vertical axis, and moving the cab support frame around the perimeter of the shaft are all controlled by one joystick. Separate controls position the mucker boom, which can be swung horizontally through a 180° degree arc towards either side of the cab. Because the cab can be rotated to any position around its vertical axis, and can also be moved in a horizontal circle around the shaft, virtually any position on the bottom of the shaft can be reached by the breaker and mucker.

Jan 1, 1981

By C. D. Litton

Submicrometer particle concentrations and average particle sizes were monitored for four full-scale sealed coal fires in the multiple-entry section of the Bruceton Experimental Mine. The data from these tests indicate that there exists a very good correlation between the submicrometer particle concentrations and the maximum temperatures measured within the coalbed. As the maximum coalbed temperature decreases with time after sealing, the submicrometer particle concentrations show a corresponding reduction. This particle-temperature correlation is in sharp contrast to the gas concentration data obtained, for which essentially no correlation exists with the measured coal-bed temperatures. The results of these full-scale tests indicate that the measurement of submicrometer particle concentrations may be a more realistic approach to determining the status of underground sealed fire areas.

Jan 1, 1981

Enhance the critical skill of hazard recognition among miners by providing quality training that can help jot performance and lead to a higher degree of safety in the workplace. Background In mining, as in many other occupations, the safety of the worker depends on his or her ability to recognize hazards in the workplace. Some of the information needed by the miner for recognizing potential areas of danger is available in the form of visual cues found throughout the mine. One aspect of the dynamic mine environment it which the task of hazard recognition is critical for al workers is that of ground control. Regardless of job responsibilities, every worker is continuously exposed to roof rib, and floor hazards. Fatality injury data for the "underground coal" segment of the mining industry continue to show that about half of all fatalities are due to falls of ground each year. It is hypothesized that some of these accident, can be prevented if miners are better able to recognize visual cues that forewarn of potential roof and rib problems.

Jan 1, 1992

To facilitate compliance with title 30 CFR 75.1001-1(b), which requires testing and calibrating of trolley line automatic circuit interrupting devices at intervals not to exceed six months. Approach Calibration of a circuit breaker ideally implies the passage of the expected fault current through the sensing circuit, and observing a successful circuit interruption at the preset level within a specified time. On trolley lines, the required current may be a few thousand amperes, with maximum duration well exceeding one-tenth of a second. Any method of obtaining this calibration current Involving the trolley wire can contribute to wire sagging and other permanent damage to the haul-age system due to the high energy dissipated during the test. Also, control to assure that exactly the required level and duration of current flow is obtained implies the use of equipment which is simply not available In the ordinary mine. Under a Bureau of Mines contract, a circuit to achieve the necessary calibration pulse was conceived and built. How It Works Two prototype units were fabricated and have been field tested by MSHA technical support engineers in under-ground mines. The equipment consists of an electronics Package 20 x 24 x 8 inches and weighing 93 pounds, including a side-mounted circuit breaker, with a set of 8 foot long detachable, AWG #4/0 leads with plier-type clamps. The total lead assembly weighs 21 pounds.

Jan 1, 1981

By J. P. Conway

The yielding-rock-bolt concept, as developed in South Africa, consists of a smooth-bore die or collar fitted to a standard rock bolt. Laboratory testing at the Bureau of Mines Spokane Mining Research Center under slow and fast strain rates showed that extrusion loads can be controlled by varying the configuration of the die bore and that theoretical analysis (using basically Sachs' theory of wire drawing) predicts extrusion loads of the different die-bore configurations. A derived equation, based on this research, can be used for designed die-thread combinations for any desired extrusion load. Dynamic loading resulted in slightly higher loads (15 percent) than static loading. The strain hardening effect, which increases yield and ultimate strength, was partly offset by adiabatic heating of the threads, which decreases strength.

Jan 1, 1975

By James P. Rider

This U.S. Bureau of Mines report describes a viewing transformation algorithm that generates a perspective view of a three-dimensional scene. This tool may be used by researchers to improve mine safety by assessing the visual capabilities of a mobile equipment operator. Three-dimensional transformations used to build the viewing transformation and techniques used to project the image onto a two-dimensional display screen are defined. The algorithm is written in the C-programming language and designed to stress portability, allowing it to work without significant modifications on numerous computers. A listing of the computer routines along with sample output is included in the report.

Jan 1, 1992

Over and above the technical support arid consulting work described in the preceding Parts of this Volume, ADL staff also provided a wide range of additional technical assistance to the Bureau on an ad hoc basis over the course of the contract, and particularly in 1973. Some of these assignments were on tasks that temporarily assumed a high priority at PMSRC, requiring a fast response, while others were more suited to conventional schedules but on communication and location topics less directly related to those in the preceding Parts. Chapter I briefly describes some of the diverse short-term assignments while Chapters I1through V treat assignments on the other topics. I SHORT-TEXM ASSIGNMENTS A sampling of short-term, fast-response assignments undertaken on mine communications and miner location for PMSRC during 1973 are given below. These assignments included technical reviews, discussions and recommendations related to the theory, experimental data, designs, and hardware implementation of experimental CW and pulse miner location EM transmitters; preparation of technical performance specifications for a miniaturized preproduction prototype CW electromagnetic location transmitter; review of specifications for a seismic signal detection experimental study; participation in technical discussions and experiments with PMSRC and equipment suppliers regarding the UHF radio/radiax-cable communications installation in the Bruceton mine; participation in an informal conference to discuss mine communication and monitoring needs and preferences with representatives of the Bureau, mine operators, and equipment manufacturers; participation in technical discussions with representatives of a U.S. mine operator and CERCHAR* concerning the characterization of faults on trolley lines and means of improving their rapid detection;** recommendation of simple signal, noise, and ground fault measurements on mine phone lines; review of an inexpensive automatic telephone dialer; preliminary discussions regarding the feasibility of adapting and assembling a collection of available telephone industry carrier equipment for installation and test in an operating coal mine; evaluation of a proposed call alert mine paging system; review of hardware designs and future experiments for a mine communication sled; design critique of a proposed six-channel narrow-band FM voice modem for carrier communication on the mine phone line; preparation of technical performance

Jan 1, 1974

By Eugene T. Sheridan

This report presents statistical data on individual plants in the fuel- briquet and packaged-fuel industries circularized by the Bureau of Mines, United States Department of the Interior, in its 1957 annual survey. This survey revealed that 17 briquet and 23 packaged-fuel plants were active part or throughout the year. The annual production capacity of the fuel-briquet industry was 3,088,000 net tons, a decrease of 17 percent from 1956. The decline in capacity was caused in part by the permanent retirement of 4 plants and also by the reduction in capacities of 4 other plants. The rate of production of briquet plants also decreased as the industry operated at 35.8 percent of capacity compared with 40.9 percent in 1956. Every operating plant in 1957 had an annual capacity exceeding 25,000 tons.

Jan 1, 1958

To reduce needless paging of persons by all phones in a mine or mill, while retaining all-location page capability. Approach Standard pager phones of any manufacturer are modified to include the option of selective calling and message holding. How It Works All commercial mine pager phones presently rely upon voice paging via a loud-speaker. When a page is initiated, every phone in the system broadcasts the audible voice page, even phones in locations where the desired person could not possibly be. The advantage of this scheme is that whole-mine paging occurs. The disadvantage is that persons soon begin ignoring pages because they occur all the time, and most are for someone else. Also, it requires considerable battery power from all phones making it necessary to change batteries very frequently, even in phone locations where personnel rarely go. In addition, if a voice page is made and not heard, there Is no way to leave the message. Therefore, persons who at a later time come near a phone, have no way of knowing a page was made and was not acknowledged. This results in situations that often have a direct bearing on safety and productivity.

Jan 1, 1980

By H. J. Fissan, G. Ananth, K. Rubow, V. Marple

"INTRODUCTION Over the past several years a new type of cascade impactor that utilizes small nozzle diameters (micro-orifice nozzles) has been under development (Kuhlmey et al., 1981; Marple et al., 1981). The small nozzle dimensions allow for particles to be collected as small as 0.024 µm aerodynamic diameter on the last stage of the impactor. To obtain a reasonable flow rate of 30 I min - i through the impactor, a large number of nozzles (up to 2000) are required per stage.Furthermore, by locating the nozzles of multi-nozzle stages in a prescribed manner (described in detail by Marple et al., 1981) and rotating the impaction plates relative to the nozzle plates, uniform deposits can be achieved on the impaction plates. As described by Marple et al. (1981), the advantages of a uniform deposit impactor over the conventional impactor that collects particles only beneath stationary nozzles are: (1) maximum use of the impaction substrate surface, reducing both particle bounce (if substrates are greased) and tare weights of the substrates (if particle mass is measured gravimetrically); (2) deposited particles can be analyzed for elemental composition by X-ray fluorescence (Dzubay and Rieke!, 1978); and (3) the pressure in the impactor can be kept relatively high compared to low pressure impactors that depend on a large slip correction to achieve small particle collection (some types of particles may evaporate at low pressures). The work described in this paper investigates two additional advantages of a uniform deposit impactor. These are: (1) the possibility of collecting two separate deposits at one time on one stage for two types of analysis techniques, and (2) the possibility of utilizing piezoelectric quartz crystal impaction plates more effectively by eliminating the deposit location sensitivity nature of the crystals (Schulze-Frohlich, 1981 ).MICRO-ORIFICE UNIFORM DEPOSIT IMPACTOR (MOUDI)A photograph of an eight-stage MOUDI is shown in Fig. 1. Each stage body of the impactor supports the impaction plate for the stage above and the nozzle plate for the stage below as shown in Fig. 2. By rotating alternate stage bodies, while holding the other stage bodies stationary, the impaction plates (or nozzle plates) will be rotated relative to the nozzle plates (or impaction plates).Rotation of the alternate stage bodies is achieved by gears on these bodies that mesh with gears on an electrically driven drive shaft of a rotating mechanism (Fig. 1 ). The alternate stage bodies are restrained from rotation by pins that rest on the drive shaft."

Mar 1, 1989

By John Nagy

The Bureau of Mines examined explosion development in a closed spherical vessel, mathematically correlating flame travel, pressure, and time with parameters defining the reaction. The model assumes that burnt and unburnt zones are separated by a thin, radially moving flame front. Isothermal and adiabatic systems are considered. Correlation with gas and dust explosion data is better for the adiabatic system, but the isothermal development is simpler and in reasonably good agreement. Interpretation of the explosion phenomena is facilitated by expressing the rate of mole change in the flame front in terms of elementary parameters. This expression is developed by examining the components of spatial-flame velocity.

Jan 1, 1969

Detect hazards associated with abandoned mine openings through the use of integrated geophysical technology. Background Many abandoned mines in the U.S. present hazards to the public. The first step in abatement of these hazards usually requires locating the abandoned workings. Recent Colorado legislation resulted in a concerted effort aimed at mitigating the hazards associated with abandoned mine workings. The Colorado Department of Natural Resources-Mine Land Reclamation Division (CDNRMLRD) is responsible for locating and backfilling abandoned mine openings such as shafts, adits and collapsed features. Many shafts and adits can be located by inspection, other openings give little or no surface expression and must be located by drilling, or through the use of geophysical methods. A common method used for locating underground mine workings is to drill throughout the suspected area. However, it is prohibitively expensive to drill holes at the spacing needed to detect backlilled shafts and small voids associated with caving and/or chimneying. It may also be dangerous to move heavy equipment over shallow mined-out workings. Geophysical investigations that employ only a single method have had mixed success in detecting hazardous abandoned mine land cavities.

Jan 1, 1991

By John C. Edwards

To have the capability to predict the development of localized spontaneous heating within a porous coalbed that is subjected to forced air ventilation or in an otherwise quiescent environment in which buoyancy develops, the Bureau of Mines developed three time-dependent mathematical models, which were used to calculate the temperature increase associated with chemisorption of oxygen by the coal. In each model, spontaneous heating is driven by an Arrhenius first-order reaction between the oxygen and coal. Two models are two-dimensional, and one is one-dimensional. In the first two-dimensional model, a constant-velocity forced convection airflow is specified; and in the other, buoyant flow is allowed to develop in the absence of forced convection. The third model evaluates the airflow from Darcy's law and a specification of the pressure at the surface of a one-dimensional porous coalbed. Numerical computations demonstrated how each model could be used to predict the onset of spontaneous heating when the porous coalbed was subjected to constraints of an imposed internal heat source or a high- temperature airflow. The effects of particle size and coalbed compaction upon spontaneous heating were examined with the third model.

Jan 1, 1990

By Paul T. Allsman

THE THREE words, research, mechanization, and automation are keynote words for mining technology during 1962. Basically interrelated, they not only express the major technologic developments in mining but are the signposts pointing out the road ahead. The process represented by each of these words is evolutionary rather than revolutionary, but developments during the past year indicate a climactical stage has been reached in the process of evolution. Mining research has progressed beyond the stage of academic discussion and is a programed activity within the Federal Government,3 the mining colleges,4 and many of the large mining companies.5 Research was a major agenda item at various national and international mining meetings in 1962. A list of these meetings would include such diverse locales as the Workshop and Symposium on Computers and Computer Applications in Mining and Exploration at the University of Arizona in March; and the 5th Rock Mechanics Symposium at the University of Minnesota, in May; the Rock Mechanics Symposium at McGill University, Montreal, Canada, in September; and the Colloquium XIII, International Society for Rock Mechanics, at Salzburg, Austria, in November.

Jan 1, 1963

By Rollien R. Wells

A REPORT of technological advancements restricted to a specific 12-month period is impractical. Inherent in the nature and development of technology is the element of time; rarely can a new process or product be attributed to a particular year. An overall picture of general trends and pattern changes, however, is indicative of technological growth. This paper presents selected observations and discussions of current metallurgical research and practices in an attempt to develop' such a picture. Of the estimated $16.5 billion spent for research and development in the United States in 1962, at least 80 percent was earmarked for the aircraft, electronics, chemical, and machinery industries. Much of the effort was of the end-use variety and was oriented closely to the national defense and aerospace programs. Only a small fraction of the total research money was directed to studies of the utilization and improvement of metals. Even if the investigations in allied fields such as solid state physics are included, the total research expenditure for metal and mineral materials barely reached $500 million. An additional $200 million was spent by industry and government for development of minerals recovery and processing methods.

Jan 1, 1963

By Yael Miron

ANFO blasting agents may undergo an exothermic reaction when they contact warm ore bodies that contain pyrite and its weathering products. The reaction is very fast at temperatures above 80° C. Urea, when present in sufficient amounts, inhibits this reaction at temperatures below 180° C. But urea-ammonium nitrate mixtures are very hygroscopic and, in certain climates, may be difficult to handle in the field. Reaction-inhibiting characteristics of three compounds were reported by the Bureau of Mines in 1979. Recently, the Bureau investigated the reaction-inhibiting qualities of five additional compounds. Mixtures of ANFO, pyrite, weathering product, and prospective inhibitors were slowly heated, under conditions simulating a hot borehole, to determine prospective inhibitor capability at temperatures up to ~175° C. Small-scale thermal tests of the same mixtures were used for verification and clarification of results. Two organic compounds, phthalimide and xanthine, similar in structure to urea, failed to inhibit the reaction. Zinc oxide and calcium carbonate were found inferior to urea, though zinc oxide raised the onset of reaction from 80° C to about 140° C. Only magnesium oxide was found to be similar to urea in its inhibitory ability at temperatures below 175° C. Based on results from analysis of quenched residues, the use of more than 5 wt-pct magnesium oxide is recommended.

Jan 1, 1982

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 Launa G. Mallett, Dana Reinke, Charles Vaught, Michael J. Brnich

As mines become safer and major disasters fewer, the number of experienced emergency responders is decreasing. This decrease will create a gap in response expertise which could have serious ramifications during future mine disasters. While working toward safety goals which may make emergency response obsolete, it would be reckless not to acknowledge that the potential for disaster still exists and that the protection of miners in such circumstances must remain a priority. The Mine Emergency Response Interactive Training Simulation (MERITS) is a computerized mine emergency simulation that meets a variety of needs. It allows personnel in leadership positions to test their knowledge and skill. Groups of individuals composed of representatives from mining companies, labor, and government agencies can practice working together during the simulated mine emergency much in the same way an actual emergency would require. An individual could also run the program to enhance his or her response skills. With this training tool, responders will be able to learn from their mistakes before facing situations with potentially catastrophic consequences. This paper discusses MERITS and its use in providing command center training.

By W. E. Robinson

Sixty samples, selected from a 2,300-foot core of the Green River Formation in Colorado, were studied to ascertain differences in the structure of the organic material present in the oil shale samples. Emphasis was placed upon relating differences in the aromatic content of the insoluble kerogen and the alkane content of the extractable material obtained from the selected samples. The methods used in determining these differences consisted of fractionation of the soluble material, carbon and hydrogen analysis, volatile material determination, carbon residue determination, oxidation rate determination, and infrared analysis. In general, it was concluded that the organic material in this core does vary in chemical structure and that same of these variations resulted from factors related to depth of burial. Other observed changes in structure of the organic material were not depth-dependent and resulted from other factors such as source material variations, biological alterations, or ecological differences.

Jan 1, 1971

By L. M. Chan, D. R. Carlson, J. H. Johnson

"This paper presents an apparatus and procedures to implement a methodology for controlling ambient air quality in a confined working environment, such as an underground mine, an underground storage area, or a tunnel. The air quality control methodology is directed at limiting the quantities of exhaust pollutants emitted by diesel-powered vehicles into the confined space by identifying vehicles that are excessive polluters. The methodology is based on tailpipe and ambient air measurements in the confined space, and the ambient air threshold limit values (TLVs) for the various diesel exhaust pollutants. The methodology consists of two computational methods; a deterioration criteria computational method to identify excessive polluting vehicles, and an engine performance computational method to determine engine performance and to provide information needed to diagnose engine faults. The methodology is designed for implementation in conjunction with a preventive maintenance program.The first part of the paper describes the mine air and tailpipe emissions measurement apparatus and techniques used to obtain data. This is followed by sections discussing the deterioration criteria and the engine performance computational methods. A section discussing some common engine emissions-related faults is also presented lastly, a proposed procedure to implement the methodology including a possible hierarchical structure for mine personnel involved to implement the procedures is presented.INTRODUCTIONDiesel-powered mining vehicles are gaining Popularity in underground coal mines and are almost universally used in underground non-coal mines due to their mobility, flexibility, and higher productivity. However, noxious gases and particulate matter in diesel engine exhaust are a concern because of the potential for being harmful to the health of miners. Diesel exhaust pollutant concentrations out the tailpipe of a mine vehicle change with time due to engine wear, inadequate maintenance, improper adjustments and other factors. This deterioration in pollutant concentrations, if not properly controlled, may adversely affect the air quality in an underground mine. To provide assurance that a clean and healthful work environment are maintained, a program is needed to identify and repair diesel engines that contribute to poor air quality. Also, earlier detection of deteriorated engines will make preventive maintenance possible, thereby eliminating further deterioration and possibly complete breakdown. Preventive maintenance also increases engine life and equipment availability in production which in turn will result in decreased operating costs."

Nov 1, 1995