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By D. D. Fischer

Recovery and separation of molybdenum and rhenium from a process solution was accomplished by a technique developed by the Federal Bureau of Mines involving a combined solvent extraction and activated carbon adsorption procedure. The processing sequence required treatment of the solution with S02 to reduce the chlorate ion and adjust the pR prior to solvent extraction of molybdenum and rhenium with a tertiary amine. Molybdenum and rhenium were stripped from the organic phase with an NH40H solution, and the strip solution was then passed through activated carbon to preferentially adsorb the rhenium. After washing entrained molybdenum from the column with a brine solution, rhenium was eluted with an MeOH-H20 mixture. The activated carbon was regenerated with water. Molybdenum was recovered as (NH4)6Mo7024 by evaporating the column effluent. Rhenium in the column eluate was reextracted with a tertiary amine, stripped from the organic phase with dilute NH40H, and recovered as NH4Re04 by evaporating the strip solution. The final (NR4)Re04 product contained < 80 ppm impurities. Sodium sulfate was crystallized from the first solvent-extraction raffinate by lowering the solution temperature to 0° C. Precious metals contained in the original process solution were adsorbed onto the activated carbon.

Jan 1, 1975

Reliably measure stress chan¬ges in order to assess stability of mine openings. Approach: A durable, permissible, sensor and readout system have been developed and tested. How It Works: The stress sensing element is a taut steel wire which is, vibrated at its natural frequency, If the tension on the wire is changed because of deformation of the sensor housing, the natural frequency of the wire changes. This effect is similar to decreasing or increasing the pitch of a violin string by loosening or tightening it. Because the stress sensor electrical output is a frequency signal, rather than an amplitude signal, its accuracy is unaffected by the resistance of the signal wire, or other attenuation. Signal wires can be a mile or longer without affecting accuracy. When a button is pushed on the readout box, the sensor wire is electromagnetically excited and vibrates at its natural frequency. That signal causes a readout in illuminated digits. (By referring to calibration chart and the previous reading, the user knows the change in stress.) This system is permissible. To install the sensor, a slightly oversize hole is drilled into the mine pillar. Next, a special tool is used to both position the sensor and wedge it in place. Figure 1, shows the sensor and its integral wedge and hole-fitting piece.

Jan 1, 1976

By N. A. Eilertsen, Rolf S. Paine

The Bureau of Mines studied the presplitting technique used for controlling overbreakage in the walls of a vertical shaft at the U.S. Army Corps of Engineers Littleville Dam project near Huntington, Mass. The periphery of the shaft, the dimensions of which were 16-1/2 feet wide by 21 feet long and 52 feet deep, was presplit (cracked) in the solid to a depth of 48 feet prior to full-depth sinking. Presplitting prevented overbreak in a fairly soft schist and provided sound self-supporting walls which required very little scaling.

Jan 1, 1965

To provide longwall operators with a method to predict methane emissions from panels with increased face width.

Jan 1, 1997

By Shirley F. Colby

Much interest has been shown recently in the possible utilization of dolomite as a source of magnesium metal, a large production of which is deemed essential for national defense. As a result, many inquiries have been received by the Bureau of Mines as to sources of dolomite. This report has been prepared primarily to augment the Bureau&apos;s present published information on the occurrence of high-grade dolomite deposits in the United States. To supplement such data, the report also defines dolomite and related rocks and describes their properties and uses. The uses are covered in some detail in Information Circular 6524 entitled "Utilization of Dolomite and High-Magnesium Limestone," published in 1931 but now out of print. All essential data on uses contained in that report have been incorporated herein, and. have: been supplemented by data developed during subsequent years. DEFINITION Dolomite is a mineral composed of calcium end magnesium carbonates combined in equal molecular proportions, expressed by the formula CaMg(C03)2. Dolomitic limestones contain considerable dolomite but also include either

Jan 1, 1941

By R. Karl Zipf, Christopher Mark

Highwall mining continues to grow in importance as a coal production method from U.S. surface mines. It may account for as much as 4% of the total U.S. coal production, according to one recent estimate. Analysis of Mine Safety and Health Administration (MSHA) accident and injury statistics shows that, overall, highwall mining has maintained an admirable safety record. Its fatality and injury rates are comparable to those for other surface mining methods, and are significantly lower than those for underground mining. No mining method is risk free, however. Highwall mining injuries have been associated with handling materials, slips and falls, machinery, powered haulage, and other types of incidents. But perhaps the greatest risk, to both personnel and equipment, is from ground control. The two most significant ground control hazards are rock falls from the highwall and equipment entrapment underground. Highwall Stability Ensuring highwall stability through proper ground control engineering is of paramount importance to safe highwall mining operations. The only fatality to occur during the last five years at a highwall mining operation was due to highwall collapse. There have also been numerous near-misses, several of which have involved extensive damage to equipment. In the central Appalachians, where the majority of highwall mining occurs in the U.S., hillseams are the most prominent geologic structures that affect highwall stability. Hillseams (or mountain cracks) are near vertical fractures in the rock that are formed in response to natural weathering and erosion of hillsides. They extend hundreds of feet down from the surface. They typically run parallel to the hillside, but they can also extend across narrow points or ridge lines. The hazard arises when rock slabs that form along the hillseams detach and fall away from the highwall face (See Figure 1). [ ] Unfortunately, it is impossible to control the location of hillseams or reliably detect their presence within a highwall. There are, however, a number of measures that can be taken to minimize the risk of failure associated with hillseams: Planning-Most operators choose to skip those areas of the highwall where a prominent hillseam daylights (See Figure 2). Existence of such areas is known for several weeks in advance of highwall mining; therefore, planning engineers can adjust the layout of highwall mining panels to locate barrier pillars within areas of questionable highwall stability. [ ] Inspection and monitoring-Daily inspection of the benches above the active highwall mining area is a prudent precautionary measure. A crack in a bench immediately above a highwall miner is shown in Figure 3. Simple displacement monitors may be useful for detecting movement along cracks that may precede a significant life-threatening failure. New tools, such as slope monitoring radar, may also prove useful in detecting motion of the rock slopes above active highwall mining operations. Good blasting practice-Most surface coal miners in the central Appalachians use pre-splitting and the familiar halfbarrels are routinely seen throughout the pits. Shorter delays along the face and longer delays between rows can direct more of the blast force parallel to the face, potentially doing less damage to the wall rock. In addition to pre-splitting, decreasing the burden, spacing and charge weight in drill holes close to the highwall will also decrease damage to the wall rock. Decreasing the highwall slope angle-Decreasing the highwall slope angle from 90° (vertical) to 70°-80°, especially in areas of known hillseam concentration, could eliminate the hillseam hazard (See Figure 4). Angled highwalls are routinely employed in many Midwestern surface mines and in some

Objective A cable bolt can be a strain-measuring device as well as a supporting device in underground mines. Placing instruments on a cable bolt allows certain characteristics of a rock mass, such as high strain and load, to he evaluated during mining and provides a means for mining engineers and mine inspectors to forecast a potential roof fall. Background Thousands of cable bolts are installed in U.S. mines each year. Studies performed by NIOSH researchers show that support loads can exceed the yield point of the steel, which can result in unstable ground conditions that pose direct safety hazards for underground workers. Rock falls can also create secondary hazards, such as caved escape ways and blocked ventilation passages. Development of methods and tools to assist in the evaluation and selection of rock supports could reduce the number of unplanned rock falls significantly. Approach Instrumented cable bolts developed at NIOSH’s Spokane Research Laboratory were used along with existing ground control systems to monitor rock mass loads and movement Axial and shear loads on the cables are determined as these loads are transferred to strain gages embedded in the king wire. In longwall, room-and-pillar, or underhand cut-and-fill mines, rock mass loads and movements can be detected down to microstrains of stress or millimeters of movement. By detecting such small amounts of ground movement and support load, early intervention to prevent a roof fall is possible, and miner safety and health are increased. How it Works Up to 10 strain gages are embedded in the king wire at whatever locations a mine ground control engineer may specify. The gages m either be set in pairs in the same plane to detect shear or set at 90° angles to detect loading in three dimensions. The cables are up to 5 meters long if they arc to be grouted with resin or up to 15 meters: if they will be grouted with cement. They arc capable of holding m ultimate lend of 214 kN and produce reliable readings to 178 kN, as shown in the calibration curve. The cables are fitted with an instrument plug for monitoring the gages and a special head for insertion into the rock. A data acquisition system, such as a Vishay strain indicator box, Campbell Scientific, or Omnidata system, is required to obtain the data for load and displacement calculations.

Nov 1, 1998

By Reinhardt Thiessen

This paper presents only the highlights of previous research on the paleobotany of coal. The accumulated material has become so vast that a comprehensive review of all findings relating to paleobotany would be far too long. The fact that coal is derived from plants is now so well-known that no further comment is required, but knowledge of the mode of transformation of plant substances into coal is not so general. The plant matter goes first through processes of semirottins-, maceration, and elimination of certain material to form peat, which is then further transformed into coal. The first stage has been termed the "biochemical process," because the more important changes take place under the influence of micro-organisms. Near the end of the biochemical action an unconsolidated peat is formed. The second or "dynamochemical process," caused by the addition of superincumbent rock strata such as sandstones and shales and application of additional pressure and possibly heat through mountain-building forces, results in the formation of higher-rank coals ranging from brown coal to anthracite. These stages in trans-formation of plant material to coal have been described in previous reports.4 The main object of this paper is to bring to the notice of paleobotanists the fact that coal contains an enormous amount of material in a remarkably good state of preservation. Although some of the coal-forming matter has lost its identity, much of the original structure is retained. A large proportion of the coal, therefore, particularly of common bright coals, comprises constituents or components that invariably have retained some of the original plant structure, and many of these structures may be assigned to certain plants. The identity of these plants and of the remains forms the subject of this paper.

Jan 1, 1941

By P. M. Gruzensky

A survey of the literature has been made covering the extraction of bismuth from raw materials, its separation from lead, and its subsequent refining. The use of aqueous, nonaqueous, and fused electrolytes in electrolytic refining is reviewed. This literature survey has been prepared preliminary to some proposed investigations concerning the electrometallurgy of bismuth, and, although an effort has been made to cover a majority of the applicable references, a critical review was not attempted and no assertion is made that this manuscript is exhaustive in nature. Titles of publications in parenthesis are translations from the language in which the reference was originally published.

Jan 1, 1954

Determine the appropriate spacing and alarm levels for carbon monoxide and smoke sensors used for fire detection in underground coal mine conveyor belt entries. Background Fire represents one of the most severe hazards in underground coal mines. Early-warning fire detection in underground coal mines is essential to successfully implement and execute evacuation and control measures. Both carbon monoxide (CO) and smoke sensors have the ability to provide reliable early-warning capability, provided that they are spaced properly and set at the appropriate alarm levels. The U.S. Bureau of Mines conducted a series of large-scale experiments where a small coal fire was used to ignite a conveyor belt at air velocities of 0.76 to 6.1 m/s. The test configuration was purposely designed to model a worst-case fire scenario for fires that develop within conveyor belt entries in underground coal mines. During the tests, CO and smoke levels were continuously measured to determine alarm times and alarm levels as the fire intensity progressed. The data from these tests indicated that for a given sensor spacing, the time to reach a preset alarm threshold depends upon the belt entry air velocity and cross-sectional area. Analysis of this data resulted in the equations and nomographs for CO and smoke sensor spacing, and alarm levels contained in Bureau of Mines RI 9380, "Fire Detection for Conveyor Belt Entries."

Jan 1, 1993

By P. T. Brooks

A process for extracting 69 percent of the vanadium from weathered Nevada dolomitic shale containing about 1 percent V205 was developed on a laboratory scale by the Bureau of Mines. The process essentially is comprised of salt roasting, leaching with dilute sulfuric acid, solvent extraction, and precipitation of vanadium as ammonium metavanadate. Carbonaceous unweathered shale was less amenable to treatment. A preliminary cost estimate for mining and processing 1,500 tons per day of weathered shale indicated a production cost of about 1 dollar per lb of V205. Considering recent sales at nearly $1. 75 per lb of contained V205, larger scale testing to obtain more definitive process design and evaluation data may be warranted.

Jan 1, 1974

By Francis Church Linxoln

"This property was explored as part of a general investigation of zinc-prodccing areas of southwestern Wisconsin at a time when an effort was being made to increase the production metals important to the Nation's war program. This report describes the work that was done and presents the data obtained.ACKNOWLEDGEMENTSIn its program of exploration of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the and that they make the greatest possible contribution to national security and economy. It is the policy of the bureau to publish the facts developed by each exploratory protect as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report. The Metallurgical Branch, P., G. Knickerbocker, chief, analyzes samples and performs beneficiation tests. Both these branches are under the supervision of Dr. R. S. Dean, assistant director. Special acknowledgment is due Professor G. H. Pett, of the Wisconsin Institute of Technology at Platteville, Wis., Jack Tracy, manager of the Mifflin Mining Co., and J. M VanMatre, representative of the Defense Property, for their assistance in the work. Acknowledgment is also due to A. F. Agnew and A. V. Heyl, geologists of the Federal Geological Survey, for furnishing geologic interpretations and lithologic studies of the drill-hole sections. All drilling was done under the immediate supervision of Francis C. Lincoln and M. Howard Berliner, project engineers, Edward P. Barrett, district engineer, Minneapolis, and E. D. Gardner, regional engineer, of the Bureau of Mines."

Sep 1, 1946

By John Ward Smith

Aragonite, co-occurring with calcite and dolomite as matrix minerals, has been discovered in Mahogany zone oil shales of Colorado&apos;s Eocene Green River Formation, posing puzzles on the geochemical patterns of their separate origins, reasons for their simultaneous existence, and their interrelation. The presence of aragonite is demonstrated by X-ray diffraction. Amounts of aragonite and dolomite are significantly and inversely related, but the calcite quantity is essentially independent of either aragonite or dolomite quantity. A geochemical pattern outlining the deposition conditions that created the Green River Formation oil shale is postulated from characteristics of the oil shale. The development of the three separate carbonates--aragonite, calcite, and dolomite--the inverse relationship between aragonite and dolomite, and the independence of amounts of calcite and the other two carbonates are shown to be natural consequences of this oil-shale genesis pattern.

Jan 1, 1973

By N. S. Dalal, V. Castranova, K. Van Dyke, V. Vallyathan, J. H. Kang

"We have reported previously that crushing or grinding crystalline silica results in the generation of silica-based radicals on the particulate surface and that these radicals can generate hydroxyl radicals in aqueous solution. Data in the present study indicate that freshly ground silica is more cytotoxic and is a more potent activator of alveolar macrophages than comparably sized aged silica. That is, compared to aged silica, fresh silica is 4.2-fold more potent in decreasing the membrane integrity of macro· phages; is 50% more potent in activating hydrogen peroxide secretion by macro· phages; and is 4.frfold more potent in stimulating cellular chemiluminescence. Prosil 28, an organosilane material, is an effective coating agent for fresh silica. It decreases the cytotoxicity of fresh silica by as much as 78% and decreases the ability of fresh silica to induce chemiluminescence from alveolar macrophages by 58%. The data suggest that surface radicals associated with freshly cleaved dust may be an important factor in the induction of pulmonary disease. Furthermore, treating dust with coating agents may substantially decrease toxicity. INTRODUCTIONThe U.S. Department of Labor estimates that over 1.25 million American workers may be exposed to crystalline silica and that nearly 60,000 may be at risk of developing some degree of occupational lung disease (Parkes, 1982; Peters, 1986). Occupations of concern include miners, stone quarry workers, sand and gravel workers, sandblasters, foundry workers, and glass workers. Acute silicosis is characterized by inflammation, alveolar lipoproteinosis, and the rapid development of respiratory disability (Banks, 1986). In contrast, chronic silicosis develops 20-40 yr after initial exposure and is characterized by the appearance of concentric hyalinized nodular lesions and the progressive development of dyspnea (Parkes, 1982; Ziskind et al., 1976)."

Mar 1, 1992

By J. H. Holden, C. C. Shale, G. R. Strimbeck, W. S. Bowie

Electrical characteristics of positive corona are presented for air in a 2 - in - diam electrostatic precipitator operating under dynamic conditions at temperatures of 600 ° to 1,500 ° F and pressures of 0 to 80 psig . Results show that current - voltage relationships depend solely on air density . Comparison of data on positive corona with previously published data on negative corona demonstrates a higher sparkover voltage and a wider range of operability for positive corona at temperatures above 375 ° F. The possibility of achieving higher voltages with positive polarity as indicated by these experiments implies several advantages for the use of positive corona in precipitators to allow better removal of suspended material from hot gases . Based on the physics of an ion in an electrical field , a theoretical equation is derived to define current - voltage characteristics of positive corona in terms of air density . Constants for the equation are evaluated from Calculated current - voltage values at different air densities agree reasonably well with experimental data .

Jan 1, 1964

Minimize the effects of underground mine conveyor belt fires by developing methods to prevent automatic fire suppression system failures. The Problem Fire protection is achieved by prevention, early detection, and planned fire-fighting response. Automatic fire suppression systems are one form of planned fire-fighting response. When these systems are properly designed, installed, and maintained they can effectively control fires. Conveyor belt fires account for about 20% of underground coal mine fires. Fire protection requirements have been established for underground locations because of potential for start and spread of fire and the restricted personnel egress in a fire situation. Belt conveyor systems arc potentially dangerous because of the high fire incidence rate, high temperatures, dense smoke, toxic gases, and rapid flame-spread rate. While investigating the conveyor fire suppression problem, the Bureau identified automatic fire suppression system reliability as a potentially serious deficiency within the mining industry. Table 1 lists common failure modes fur three Fire suppression system types. This table summarizes findings of Mine Safety and Health Administration electrical inspectors responsible for inspection of belt protection automatic fire suppression systems. Batteries, contact points, control wires, and electric servocontrols are all prone to failure. Figure 1 shows rock-dust-contaminated relay contact points. This condition is dangerous because of the chance of intermittent failures, which might allow systems to pass annual functional testing, yet fail during actual fire emergencies.

Jan 1, 1989

By E. L. Burwell

Preliminary results of an in situ oil shale retorting experiment conducted by the Bureau of Mines in a shallow bed of Green River oil shale at Rock Springs, Sweetwater County, Wyo., are described. Eleven wells were drilled into a 20-ft-thick section of the shale lying between 68 and 88 It deep, and attempts were made to connect the wells through the shale with a fracture system created by application of high-voltage electricity (electro-linking), hydraulic fracturing, and explosive fracturing. Ignition of the shale through the central well was easily achieved with a propane burner, and shale oil began to collect in three wells within 3 hours. Propane injection was discontinued after 7 days, and combustion continues, although attempts to control the direction of the combustion front have been unsuccessful. Production rates as high as 4 ½ barrels of nil per day have been recorded, but too little is known about underground conditions to permit an estimate of recovery efficiency at this time.

Jan 1, 1969

By Herbert L. Lines

This paper is one of a series on mining and milling methods and costs published by the Bureau of Mines. The Ash Peak mine of the Veta Mines, Inc., Duncan, Ariz., is of particular interest in that the only metal of commercial value in the ore is silver. The silver is concentrated by flotation; the concentrate is shipped to a smelter for treatment.

Jan 1, 1940

By W. L. Staker

The Bureau of Mines investigated the use of shredded automobile scrap for copper cementation. Air agitation was used to improve the cementation rate and prevent excessive buildup of copper on the iron. The pieces of scrap were too large to be properly evaluated in the laboratory; therefore, a pilot scale test unit was constructed and the process tested at field locations. Pregnant solution was obtained from industrial leaching operations, processed in the test unit and the barren solution and cement copper were returned to the plant process stream. The test results showed that the air-agitated launder containing auto-mobile scrap was an effective means for recovering copper from leach solutions. A continuous l4-day test run was made without a noticeable decrease in cementation efficiency. The most suitable scrap product was obtained from incinerated automobile hulks shredded in a hammer type of shredder. However, it was necessary to remove small pieces such as nuts and bolts because they interfered with the discharge of the copper product.

Jan 1, 1976

By H. C. Young

This paper deals with roof bolting in Alabama coal mines and iron-ore mines from the time it was introduced in early May 1948 to May 1, 1953, a 5-year period. The Tennessee Coal & Iron Division of the United States Steel Corp. began systematic roof bolting in early May 1948 in a coal mine and in an iron-ore mine, which had some of the poorest roof conditions in the Alabama mines. After the efficiency of roof bolting had been proved by the Tennessee Co. it was gradually adopted by other companies throughout the State, until in May 1953 approximately 53 percent of Alabama&apos;s total coal production and 100 percent of Alabama&apos;s total iron-ore production, mined underground, was being produced from roof-bolted areas. Statistics in this report will show the advancement made in roof bolting in the 5 years and also the amount of roof bolting that was being done as of May 1, 1953. Significant progress has been made in the coal and iron-ore mines of Alabama in reducing the roof-fall fatality rates during the past several years by adopting systematic roof bolting. The groundwork was laid through successful experiments early in 1948 by the Tennessee Coal & Iron Division of the United States Steel Corp. in cooperation with the Federal Bureau of Mines. This experimental work was based upon the previous experience of the St. Joseph Lead Co.2/ in its Southeastern Missouri mines.

Jan 1, 1954