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Reduce well construction and operation costs associated with in situ leach mining while increasing mineral recovery. Approach To accommodate the size of centrifugal pumps presently in use, in situ leaching production wells are typically drilled to 6 inches in diameter, while monitor wells are drilled to measure 4 inches in diameter. However, in order to reduce the cost of drilling these larger diameter wells and to increase recovery, the Bureau has developed jet pumps which have smaller diameters than centrifugal pumps of the same capacity. This allows both production and monitor wells to be drilled smaller. Bureau estimates indicate that the cost of drilling a 3-inch-diameter production well at in situ leaching operations would be about 35 percent less than the cost of a 6-inch well. Similarly, the cost of drilling a 2-inch-diameter monitor well would be about 26 percent less than the cost of a 4-inch well. Such significant savings in the cost of drilling these wells would effect a substantial reduction in total capital cost. Use of the new jet pumps can also increase the percentage of recovery because less costly wells allow closer well spacings, improving the distribution of the leach solution. How the System Works After the borehole is cased, the new small-diameter jet pump, along with piping and accessories, is installed and connected to a centrifugal pumping unit on the surface. High-pressure water from the surface pump is forced through a nozzle into the venturi of the jet type pump injector. This jet action lifts the leach and mineral-bearing solution to the surface.

Jan 1, 1984

By Wm. C. Dean

The location of trapped miners from their seismic signals will be in- accurate if we assume the P-wave propagation velocity is a constant. P- wave velocities are anything but constant in regions about mines, so some calibration is necessary to obtain more accurate seismic locations. The reference event method compares the time arrivals of signals generated by the miners with those previously recorded from a reference or calibration event in the vicinity of the miners. This method locates the miners' position relative to the calibration source. Hence, the location of the miners is absolute if the reference event position is known absolutely, usually from surveys and mine maps. Advantages resulting from the system, besides greater accuracy, are locations independent of the velocity model assumed, the same solution from the full array and from any subset of four or more seismometers in the array (three if the miners' depth is known), fewer seismometers required, and no complex computers required for analysis. VELA Uniform experience shows that the accuracy of locations of teleseismic explosions and earthquakes is improved by an order of magnitude over locations computed from average travel time curves. Each calibration event is applicable only over a limited range. We recommend a field test of the method at a mine to measure its location accuracy, the range of effectiveness for each calibration event, the number of seismometers needed, and the number of reference events required per mine. From these experiments we could decide whether the reference event method was useful and, if so, what form a practical rescue system would take.

Jan 1, 1974

By J. W. Pall

The method of mining bituminous coal in Pennsylvania cannot be treated in an extended manner in this publication since this would require more space than justified. The general plan of operation of most mines is on the room and pillar system, using double entries from which the rooms are driven In the early mining in the Pittsburgh coal bed the "checkerboard" plan was much used, but this entailed a large loss of coal in the blocks of coal that were left standing. In recent years there has been a tendency towards the adoptions of the panel, room and pillar method, also the block system, which ad mats of concentrated mining within a relatively small section of the mine It is not unusual to use 4, 6, or 8 parallel entries for the panel development. The longwall advancing method has been tried in some of the thin beds of the central coal field, but so far it has not passed beyond the experimental stage. The average extraction' of coal throughout the State is 714 per cent, but it is estimated that 15 5 per cent of the loss is avoidable, so the actual extraction should approximate 87 per cent. Pennsylvania is exceptionally well provided with means of transportation by trunk lines, branches, and by intra State railroads, among which are the Pennsylvania, Baltimore & Ohio, New York Central, Buffalo, Rochester & Pittsburgh, Western Maryland, Bessemer & Lake Erie, Pittsburgh & West Virginia, Pittsburgh & Lake Erie, Erie, Monongahela Division, and Montour railroads, all of which reach some of the bituminous mines The Monongahela River furnishes water transportation for Allegheny, Greene, Fayette, and Washington counties During 1923 the coal traffic on this river amounted to 18,709,084 tons, and of coke, 385,426 tons Coal is moved on the Allegheny River also, the total in 1923 being 911,178 tons s.

Jan 1, 1928

By David R. Forshey

This Bureau of Mines report presents a quantitative theoretical analysis of a coupled gasdynamics-heat release system involving the kinetics of water condensation in and behind the rarefaction wave in a shock tube using the method of characteristics. The merger of characteristics to form a shock wave is included.

Jan 1, 1977

By Benjamin W. Haynes

The Bureau of Mines conducted research to devise technology for increasing the Nation's mineral supply by recovering valuable constituents from currently discarded waste materials. Municipal solid waste (MSW), presently a major disposal problem, represents a significant source of metals, glass, and a combustible fraction that can be used to supplement coal in generating heat and electricity. As part of the total metallurgical system to treat MSW, this study evaluates the combustible fraction of MSW to characterize the various combustible components and to identify the principal sources of elements that eventually may be objectionable from corrosive or environmental considerations. Several possible sources for cadmium, chromium, cobalt, copper, lead, nickel, and zinc have been tentatively identified. These sources are pigments, inks, paper stock, and additives to plastics. A correlation between industry consumption values and measured concentrations in MSW was found for several elements.

Jan 1, 1978

Reduce workers' dust exposure by capturing airborne coal and quartz dust generated by a continuous mining machine. Approach Install a water-powered scrubber system operating at 1,000 psi on the boom of a continuous miner at the conveyor throat. Dusty air from the face area is drawn through the scrubber and cleaned air discharged into the return. How it Works Most coal mines use exhaust face ventilation to send fresh air over the miner operator and contaminated air behind the line curtain to the return. The problem with exhaust ventilation is that the line curtain should be within 10 ft of the face for maximum effectiveness. If the line curtain is not extended properly, or water sprays for dust control are poorly installed, dust rolls back towards the operator. An effective way of removing this dust is with a scrubber mounted on the mining machine.

Jan 1, 1988

By John Durkin

Field studies have been conducted in a large number of coal mines throughout the U.S. to determine the effectiveness of electromagnetic techniques in locating men trapped underground following a mine disaster. Data from these tests have been used to generate models of expected signal and noise distributions as found above mines throughout the coal fields. These distributions have aided in placing the expected performance of a through-the-earth electromagnetic communications technique into a probabilistic framework. Results indicate an expected 45% probability of detecting a miner's signal from a depth of 1,000 ft, a depth which exceeds 903 of the coal mines within the U.S. and a 90% probability at a depth of 500 ft, a depth which exceeds 50% of the mines.

By Todd M. Ruff

The lack of visibility near earthmoving equipment resulted in six fatalities in U.S. surface mining operations during 2003. These accidents were the result of either a piece of equipment striking another vehicle or worker, or the equipment traveling over the edge of an embankment. Figure 1 is an example of a recent accident that resulted in serious injuries to one worker and fatal injuries to two others when a van parked in front of a haul truck. Two fatalities occurred in separate incidents when front-end loaders struck workers. Another two workers were killed when their equipment backed over the edge of a highwall or dump point [1]. There is clearly a need to provide better information to equipment operators regarding their surroundings. [ ] Researchers at the National Institute for Occupational Safety and Health (NIOSH), Spokane Research Laboratory, are working to reduce these accidents by developing systems that sense obstacles and changes in terrain near the equipment and provide this information to the operator. Many off-the-shelf proximity warning systems that were developed for automobiles, light trucks, and recreational vehicles were evaluated on off-highway dump trucks [2]. Many limitations were found with existing systems, including frequent false alarms, limited detection range, a lack of specific information on an obstacle (e.g., location, identity), difficulties in finding suitable mounting locations, and an inability to withstand the environment. These limitations have necessitated the development of new systems designed specifically for large, off-highway, earthmoving equipment. New off-the-shelf systems available for mining equipment include radar and tag-based detection systems. Prototype systems now being developed include a proximity warning system based on the Global Positioning System (GPS) and a computer-assisted stereovision system. Development of these new systems was accomplished by working with manufacturers to modify existing systems to meet the needs of surface mining and through cooperative research with organizations to develop completely new solutions. A typical proximity warning system consists of a sensor or antenna mounted on the equipment that detects the presence of obstacles and an alarm interface in the cab of the equipment. Some systems, as described in more detail below, also require that other vehicles and personnel on the ground be outfitted with electronic tags that transmit an “I’m here” signal back to the system (e.g., radio signal detection systems or GPS). Many types of proximity warning systems are on the market, but they are not all discussed in this paper. APPROACH In past work, engineers at NIOSH evaluated several off-the-shelf proximity warning technologies in order to verify their effectiveness on off-highway dump trucks [2]. Dump trucks were chosen because of the number and severity of accidents involving this type of equipment and because extensive blind areas around these trucks are typical. This experience allowed engineers to limit the number of systems chosen for long-term tests at mine sites to those systems showing

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

MINE VENTILATION NETWORK ANALYSIS

Jan 1, 1977

By S. J. Pearce

"INTRODUCTION AND SUMMARYComplaints have been made regarding dust respirators that may be used in coal-mining operations. Some of these complaints may be due to improper use of the respirator, inadequate knowledge of its purpose and mode of functioning, poor choice, poor fitting, or inadequate maintenance. It is hoped that this circular will answer these complaints by discussing the various factors relating to the proper use of dust respirators in general and in coal mines in particular.It is pointed out that dust respirators are not to be used as a substitute for dust-control measures. The construction, functioning, choice, fitting, and maintenance of dust respirators are discussed.FIELD OF USEThe function of the dust respirator is to prevent the wearer from inhaling harmful quantities of dust by removing dust from the air he inhales.A dust respirator is not to be used as a permanent substitute for dust-control measures. It is to be used as a temporary substitute until dust-control measures can be instituted or as a protective means where dust-control measures are impracticable, as in applying rock dust in bituminous-coal mines.The following sections of the ""Federal Mine Safety Code for Bituminous-Coal and Lignite Mines in the United States"" 2/ emphasize the fact that every effort should be made to keep the amount of dust in the air of the working places as small as possible:"

Mar 1, 1950

By John R. Reeves

The principal oil aha.le in Indiana ie known as the New Al'baZ\Y shale. It 11 ot Devonian age, and ia usually correlated with, although not certainly of the 1ame age a,, the Antrim shale of northern Michiga.. the Ohio shale of Ohio, and the Chattanooga shale ot Kentucky. Termescae • a."ld Georgia. The nqtmal thickneaa of the formation 1n Indiana 1e a.bout 100 faet, ltbough 1n the region of its out­ cro;l the tall th!::kne,111 io rarely exposed because cf the general d:.p of the strata, which is 11 about 30 feet per mile to the west. With the exception ot thin local pha1e1, the entire thickness is oil shale,

Aug 1, 1922

By J. H. Maysilles

The Bureau of Mines is examining a variety of low-grade uranium ores because projections indicate that an appreciable percentage of future U.S. uranium production will be derived from resources containing 0.01 to 0.1 percent U308. One possible source is represented by a granitic material from Wyoming; the available samples contained 0.06 and 0.12 percent U308. Tests were conducted to explore the general leaching characteristics of this potential resource. The material responded to both acidic and alkaline leaching techniques. Conventional acid leaching extracted 93 percent of the uranium in 18 hours; the required acid addition was 50 to 100 pounds of H2S04 per ton of ore, and the oxidant addition was 3 pounds of NaCl03 per ton of ore. The acid consumption continues after maximum uranium recovery has been reached; this effect may complicate heap or in situ leaching with acidic solutions. Some variation in reagent requirements was noted between the two ore samples. Conventional carbonate leaching with strong solutions at 85° C extracted 94 percent of the uranium in 24 hours. These granitic materials also showed some response to dilute carbonate solutions, and the results suggest that the material may be chemically amenable to heap or in situ leaching with dilute carbonate solutions.

Jan 1, 1977

By M. E. Poad, M. M. McDonald, J. C. Johnson, W. G. Pariseau

A U.S. Bureau of Mines case study of pillar recovery in high-grade ore near the Ross shaft at the Homestake Mine, Lead, SD, has demonstrated the usefulness of the finite-element method for evaluating shaft pillar mining plans and shaft stability. In this study, borehole extensometers and other instruments were installed to provide data for model verification and to monitor shaft displacement. Results of a recalibrated two-dimensional model (UTAH2)confirmed the premining stability evaluation. However, after mining began, concern developed because of cracks and other signs of ground motion that appeared at considerable distances from the area of active pillar mining. An intense three-dimensional modeling effort using the computer modeling program UTAH3 was initiated. The results again showed the observed effects were within expectations and that the shaft would remain safe. Three-dimensional analyses of alternate pillar mining scenarios indicated that more of the shaft pillar ore reserve could be recovered than previously thought on the basis of two-dimensional analyses. This report focuses on startup and implementation of the three-dimensional model, calibration of the three-dimensional model, and application of the model to shaft pillar mining.

Jan 1, 1996

To improve the reliability of the Bureau developed bore-hole gage now widely used to determine the absolute state of stress in rock. Approach Use the knowledge gained by extensive field tests to design a more rugged and reliable Instrument using lighter and stronger materials. How It Works The original gage consisted of a stainless steel cylinder 1-3/8 Inches In diameter and 10-1/2 inches long. The new gage is made from titanium. This lighter material reduces the weight of the gage by 43 percent, which enhances the gage placement and depth of overcoring in vertical up? holes. For added strength, the titanium case and placement end are now threaded to the gage body instead of using screw fasteners. Three pairs of strain gaged transducers are positioned to measure the diametral deformation of a 1-1/2 diameter borehole at 60-degree intervals around the Inner surface of the borehole. Each transducer consists of a beryllium copper cantilever with a strain gage cemented on each side. These transducers are secured Into the gage body by a tapered shank for minimal creep. The transducers opposite each other are wired together to form a 4-arm external bridge circuit. A pair of transducers is referred to as a component. Any deformation of the borehole, which occurs during overcoring, is detected by pistons which translate the motion to the components. Each

Jan 1, 1982

By Willard L. Hunter

The separation of tantalum and columbium by solvent extraction was under-taken as part of the Bureau of Mines research program to improve methods for extracting, separating, and reducing these elements to metal. The diethyl ketone aqueous HCl-HF system was one of several systems studied to determine the effect of metal and acid concentrations in aqueous solutions upon the transfer of tantalum and columbium into selected ketones. The tantalum-columbium oxide mixture used in this investigation was obtained by chemical extraction from Geomines slag. The investigation showed that tantalum 99.4 percent pure and columbium 97.2 percent pure can be produced by the selective transfer of tantalum into diethyl ketone from a solution of 2-N HF and 1-N HC1. The relatively low acid concentration necessary for tantalum transfer and the excellent selectivity of the system recommend its use for the separation of tantalum and columbium.

Jan 1, 1961

Provide a means for reliable in situ stress change measurements in soft, friable geologic materials under high stress. Background Effective mine design requires a knowledge of changes in rock stress generated by a mining operation. In situ stress measurement can provide a means of obtaining this knowledge from an active mine for the ultimate purpose of design verification and analysis. The Bureau of Mines has designed and tested a device for measuring changes in rock stress-the borehole platened flatjack (BPF). It has found application in investigating stress anomalies due to geologic structures, stress concentrations from multiple seam interaction, and stress abutments from pillar retreat and longwall mining.

Jan 1, 1990

To provide safer and more efficient mine operations by improving the operational performance of underground trolley line communication systems. Approach The dc trolley line provides a convenient means of In-mine communication since it can carry signals to each phone on the system whether the phones are in mine vehicles or in a fixed location such as that of a dispatcher. In many cases, however, the system does not perform satisfactorily. Short communication range, noise, and dead spots commonly interfere with effective communication. These problems are inherent with the trolley line, which was designed to transmit power and not communication Signals. As a power line, the trolley line is connected to rectifiers and feeds many loads such as motors, water pumps, track block lights, etc. Each of these devices represents a low impedance radio frequency (RF) shunt that seriously reduces carrier communication Signals. Performance is therefore often poor and can be improved only if the effects of the various shunts can be reduced. The Bureau of Mines has developed numerous methods applicable to either existing or planned phone systems which can improve communication range and reduce the shunting effects of the various loads.

Jan 1, 1983

By Kevin Connor

During 1984, minerals exploited in Burundi included gold, kaolin, lime, and peat. Over 1,100 troy ounces of gold was extracted and traded during the year as a result of the lifting of the Government ban on gold mining in mid-1983 and the establishment of an artisan mining program and licensed trading counters. Almost 2,000 tons of kaolin was mined for the manufacture of insecticides. Lime production was for domestic fertilizer applications. Amoco International and the Government signed an accord late in the year for a petroleum exploration program covering 600,000 acres of Burundi's onshore Ruzizi Plain and part of northeastern Lake Tanganyika. Amoco was expected to begin the exploration program by mid-1985. Anticipated program costs could run as high as $200 million.2 The Finnish company Ekono Oy completed its peat industrial energy development studies for the Buyongwe peat deposits of northern Burundi by the end of the year. The project assessed the quantity and fuel quality of 13,000 hectares of peatland and was part of a larger study for developing the Musangati lateritic nickel deposits of Burundi, estimated at 3% of the world's reserves of nickel. The Buyongwe peat would fuel dryers and an electrical generating plant for supplying power to nickel ore processing facilities. Briquetted peat would also be used as a substitute for wood and charcoal, presently the main sources of rural energy in the country and rapidly depleting because of deforestation. The study also evaluated the most economical methods to harvest the peat bogs. The study was financed by the International Development Association (IDA), United Nations Development Program (UNDP), Finnish Aid-Finnida, and the Burundi Government.

Jan 1, 1986

By Kathleen Kowalski-Trakofler, Edward Barrett

Problem: It is estimated that 5 to 10 arc flash explosions occur in electric equipment every day in the United States. In the mining industry the largest single injury category of electrical injuries are caused by non-contact electrical arcs. Method: This investigation progressed in two phases: (a) 836 Mine Safety and Health Administration (MSHA) reports of electric arcing incidents that occurred over a period of 11 years were reviewed, and (b) personal interviews were conducted with 32 individuals. A theoretical Safe Job Performance Model guided the study. Results: Behavioral dimensions were identified and included the effect of worker experience, judgment and decision-making ability, behavioral and organizational controls, and safety culture. Summary: The National Institute for Occupational Safety and Health (NIOSH) conducted an investigation of behavioral components associated with arc flash incidents and developed recommendations for interventions based on findings. Impact on Industry: This study fills a vacuum in electrical training with a focus on the organizational and behavioral aspects of arc flash incidents. There search is cross-cutting in its scope, in that the results apply not only to mining and construction, but many other industries employing electricians. Although the majority of mine electrical injuries are the results of burns from electrical arcs, few miners are aware that such a hazard exists. A safety training program, which includes a video and an instructor's discussion guide, was developed for electricians based on this study's findings. “Arc Flash Awareness” was released in 2007 (DHHS NIOSH PublicationNo.2007-116D) and is available through1-800 CDC-INFO. Phone:1-800232-4636 or email cdcinfo@cdc.gov. It is also available from MSHA at MSHADistribution@dol.gov or 304-256-3257 (DVD-576). Private industry is producing Portuguese and Spanish language translations.

Provide a method for obtaining in situ measurements of coal cutting forces which are needed for mining machine design. Approach A portable in-seam testing device is carried to the face of an underground coal mine heading to measure the cut-ting force encountered by a continuous miner pick directly at its maximum depth of cut. How It Works The tester frame is attached directly to the coal surface with four one inch diameter threaded studs resin-bolted into 1-1/4 inch diameter holes which are drilled 30 inches deep. Spherical nuts and washers compensate for misalignment between the bolts bearing plate, and traverse beams. Spacers can be placed over the studs to assure that the traverse beams remain in the same plane. Cutting forces are applied by a hydraulic cylinder that moves the pick of the tester through a twin-chain arrangement which gives a 20-inch cutting stroke with

Jan 1, 1982