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By W. G. Pariseau

The U.S. Bureau of Mines has been conducting a series of rock mechanics investigations at the Lucky Friday Mine in the Coeur d'Alene Mining District of northern Idaho. The present study uses rock deformation measurements to validate and calibrate a geomechanical model of the experimental Lucky Friday underhand longwall (LFUL) stope on the 5,100-ft level of the Lucky Friday Mine, Mullan, ID. The calibrated three-dimensional, finite-element model and measurements of rock mass displacement show a correlation of 0.795. The calibration reduces rock mass modulus to 14 to 17 pet of laboratory values and rock mass strength (with an energy rule) to 37 to 41 pet of laboratory values. This model suggested that stress-related ground control problems would be encountered west of the stope where the vein makes a right-angle turn and then splits. Rock burst activity was concentrated in this area during mining of the LFUL stope.

Jan 1, 2010

By William Hustrulid

The National Institute for Occupational Safety and Health (NIOSH), as part of a comprehensive program to improve mine safety through the widespread acceptance of careful excavation principles in drifting, have revisited standard drift round design concepts. Although the initial emphasis was on contour row design and providing improved design tools for blasting with de-coupled charges, the focus has broadened into the development of a general gas pressure-based drift round design approach. The concept of a damage radius (Rd) for a given explosive-hole-rock mass combination is introduced. With the damage radius as the basic building block, the blast holes are positioned on the face, beginning with the buffer row, to achieve the desired excavation size, shape and smoothness. The design of the contour row of holes is also performed using a pressure-based approach. The paper presents in some detail the overall approach and the required gas pressure-based design equations.

Jan 1, 2007

By W. E. Wallace

Volume-rate-of-flow measurements were made of the flow of mercury through porous samples under conditions of no field, magnetic field transverse to the direction of flow, and transverse magnetic field and electric current to determine if a magnetic method might be potentially useful in the study of pore-size distribution. No change was observed in the flow rate from the application of a magnetic field alone. The application of both field and current produced an electromagnetic pumping action with or against the direction of flow, depending upon the direction of the electric current. This pumping effect was observed to be greater in a rectangular porcelain sample than the calculated value for an equal-Sized open channel.

Jan 1, 1969

The Bureau of Mines equipped a longwall shearer with a water-jet-assisted cutting system and measured dust levels during the cutting of a simulated coal block. The block was cut dry, at a conventional water spray pressure of 190 psi, and with water-jet-assisted cutting pressures ranging from 1,000 to 6,000 psi. At water pressures of 3,000 psi and higher, dust concentrations were reduced by as much as 85 pct via water-jet-assisted cutting in comparison with conventional water sprays. This reduction was achieved without any increase in the water flow rate.

Jan 1, 1986

By Louis A. Panek

The practice of roof bolting, now recognized as an effective method of support, is based largely on rule of thumb. Among the various applications of bolting, the support of stratified mine roof is by far the most common. The general principles relating to this type of reinforcement are presented in two companion reports; the first describes the function of the bolts, the bolting pattern, and the behavior of bolted roof (1), 2/ and the second describes the design of the models and the theory of the experimental method (2). This report presents a rational method for designing systems of vertical bolts to reinforce horizontally bedded mine roof, developed from model tests. The structure treated herein may be described as follows: The immediate roof, consisting of beds of like material and equal thickness with no bond between them, is reinforced by vertical bolts installed in straight lines across the opening; the case of suspension is excluded because the bolts are assumed not to extend above the immediate roof. The assumption is made that the behavior of the lowest bed approximates that of a rectangular plate clamped along two opposite sides (the ribs). These specifications represent approximately the roof conditions encountered in mining bedded deposits of all kinds - coal, potash, iron ore, etc. Thus, for the design of a roof-bolting system a quantitative solution to the following problem is required: For a roof composed of beds of given thickness and physical properties, how does the support depend upon the length, spacing, and tightness of the bolts?

Jan 1, 1956

By B. J. Scheiner

The Federal Bureau of Mines investigated an electrolytic oxidation procedure for extracting lead, zinc, copper, and silver from lead-zinc concentrates. Concentrates slurried in brine were pumped through the anode compartment of electrolytic cells equipped with selective ion diaphragms. Hydrochloric and hypochlorous acids generated in the anode compartment converted the metal sulfides in the concentrates to soluble metal chlorides, sulfate ion, and elemental sulfur. Metal extractions of 92 to 100 pct were obtained from lead-zinc concentrates at an energy consumption ranging from 1.5 to 5.0 kW-hr/lb metal extracted. Sodium hydroxide was formed in the cathode compartment at a current efficiency of >99 pet. Silver and copper were extracted from refractory tetrahedrite minerals, but the process entailed a relatively high energy consumption. Sealing the top of the diaphragm cell utilized the chlorine more effectively, thereby reducing energy consumption 10 to 50 pct.

Jan 1, 1975

By Lars Osen

The Bureau of Mines investigated (1) the effect of torsion on yield and ultimate strengths of bolts when the torsion is applied first and tensile load is applied independently of torsion and (2) various methods of increasing the tension-torque ratio and/or narrowing the data spread of the tension-torque relationship. A special torsional attachment was fabricated to attach to a universal testing machine to independently subject rock bolts to combined tensile and torsional loads. It was found that initially installed torsion is nullified during tensile loading and the tensile yield and ultimate strengths are not significantly reduced. Lubricating various components of a bolt assembly or using hardened washers will improve the tension-torque relationship during conventional installation; however, the torsional load is not nullified during this type of loading. Hence, a bolt is subjected to a combined stress throughout the loading cycle; the yield point will thus be lowered compared with the pure tensile yield if care is not taken during installation to stay below the torsional yield.

Jan 1, 1966

Develop a more efficient method of testing the integrity of in-situ leach mining operations. The Problems For economic and environ-mental reasons, in-situ leaching operations must be sure that wells do not leak. Loss of solution in large quantities can be expensive in itself, and if such losses result in pollution the costs can be even higher. Wells are usually tested for leaks by sealing them with packers, pressurizing them and monitoring the pressure drop. However, many commercially-available packers are designed to be used in steel-cased wells rather than the fiberglass-or plastic-cased wells used for in-situ mining. These packers are heavy, cumbersome, expensive, and often leak. In addition, commonly used well-integrity-test systems require lengthy test periods and drill rigs or hoist trucks with rigid pipes must be used to run the packers in and out of the well. The Bureau of Mines has developed a mobile, self-contained leak-testing system that is faster, uses trailer-mounted equipment that can be operated by one person, and features a new inflatable packer.

Jan 1, 1985

By J. Douglas Causey

In 1984, at the request of the Bureau of Land Management, the Bureau of Mines studied 29,020 acres of the 43,165-acre Terry Badlands Wilderness Study Area (MT-024-684) in order to evaluate its mineral resources. Within this report, these 29,020 acres are referred to as the study area. Located in Custer and Prairie Counties, MT, the study area is about 2 miles northwest of Terry. The study area is underlain by essentially flat-lying units of the Fort Union Formation of Paleocene age with some Quaternary alluvial deposits in stream valleys. No mines or prospects were found in the study area. Bentonitic clays and lignite coal units were examined and sampled; however, no clay resources or coal reserves were identified. Estimates of coal resources will be reported by the U.S. Geological Survey in a joint U.S. Geological Survey-U.S. Bureau of Mines publication. Gravel along the Yellowstone River, a source of agate for private collectors, could also be used as sand and gravel aggregate although material on the south bank of the river is closer to population centers and road systems. Clinker found in the study area could be a source of road metal, but is not well situated in relationship to areas of use. No geothermal resources have been identified although water suitable for direct heat applications may underlie the study area. All the area is leased for oil and gas exploration.

Jan 1, 1985

By G. J. Conroy

This Bureau of Mines study was initiated to determine whether or not a large-scale investigation of 400-Hz applications in coal mines was justified as a means of increasing safety in operations due to size and weight reductions in portable and other mining machinery. Potential uses for 400-Hz power in mining operations are explored, and cost and size comparisons with 60-Hz systems are made. The use of variable-frequency motor drive is suggested for conveyors. The conclusion was reached that there is no significant potential safety increase due to a general size and weight reduction, as the fact of such general reduction cannot be demonstrated.

Jan 1, 1974

By Gerald L. Finfinger

The Bureau of Mines conducted an experimental degasification project in Island Creek Coal Co.'s Virginia Pocahontas No. S mine. Methane from the overlying Pocahontas No. 4 coalbed was entering mine workings in the Pocahontas No. 3 coalbed through fractures in the roof rock. Small-diameter (l-S/B-inch) holes were drilled into the overlying coalbed to reduce the gas pressure and intercept methane flows, which were piped to the surface through an underground 6-inch-diam steel pipeline. The total methane flow rate from the vertical holes averaged 150,000 ft3/day for the first month. Methane flows into the mine were reduced by 47 pet, thereby demonstrating the effectiveness of this form of degasification in reducing ventilation requirements and providing a safer working environment.

Jan 1, 1979

By Hugo E. Camargo

In an effort to reduce Noise Induced Hearing Loss (NIHL) in the mining industry, the National Institute for Occupational Safety and Health (NIOSH) is conducting research to develop noise controls for mining equipment whose operators exceed the Permissible Exposure Level (PEL). The process involves three steps: 1) Noise source identification (NSI), 2) development of noise controls, and 3) evaluation of the developed noise controls. For the first and third steps, microphone phased array measurements are typically conducted and data are processed using the conventional beamforming (CB) algorithm. However, due to the size and complexity of the machines, this task is not straight forward. Furthermore, because of the low frequency range of interest, i.e., 200 Hz to 1000 Hz, results obtained using CB may show poor resolution issues which result in inaccuracy in the noise source location. To overcome this resolution issue, two alternative approaches are explored in this paper, namely the CLEAN-SC algorithm and a variarion of an adaptive beamforming algorithm known as Robust Capon Beamformer (RCB). These algorithms were used along with the CB algorithm to process data collected from a horizontal Vibrating Screen (VS) machine used in coal preparation plants. Results with the array in the overhead position showed that despite the use of a large array, i.e., 3.5-meter diameter, the acoustic maps obtained using CB showed "hot spots" that covered various components, i.e., the screen deck, the side walls, the I-beam, the eccentric mechanisms, and the electric motor. Thus, it was not possible to identify which component was the dominant contributor to the sound radiated by the machine. The acoustic maps obtained using the RCB algorithm showed smaller "hot" spots that in general covered only one or two components. Nevertheless, the most dramatic reduction in "hot" spot size was obtained using the CLEAN-SC algorithm. This algorithm yielded acoustic maps with small and well localized "hot" spots that pinpointed dominant noise sources. However, because the CLEAN-SC algorithm yields small and localized "hot" spots, extra care needs to be used when aligning the acoustic maps with the actual pictures of the machine. In conclusion, use of the RCB and the CLEAN-SC algorithms in the low frequency range of interest helped pinpoint dominant noise sources which otherwise would be very hard to identify.

Jan 1, 2009

By C. E. Coleman, Joseph D. Davis

During some distillation experiments conducted by the Bureau of Mines in cooperation with the Trent Process Corporation it was observed that amalgams of heavy petroleum oils and finely pulverized coal tended to produce a denser coke than that obtainable from the coal when retorted alone . Even anthracite coal when retorted with oil yielded a coke . This led the writers to believe that by mixing a lowrank coal ( sub-bituminous or even lignite ) - with asphaltic oil and retorting it, a coke suitable for domestic fuel could be made . Thus there was contemplated the production of domestic coke and the utilization of a low- grade oil in one operation . - In order to decide on the practicability of this process , it was necessary to know the value of products obtainable by such a method , as compared with those obtained by separate distillation . A laboratory method was therefore devised , and while it was realized that no small - scale testing apparatus for destructive distillation gives results that are directly applicable to commercial - scale operations , by keeping distillation conditions uniform for comparative tests , results were obtained valuable for purposes of comparison . The plan was to distill mixtures of coal and oil in a laboratory retort , and then distill the constituents separately under the same conditions . The comparative quantities of products yielded were thus directly obtained , and their quality was determined by analysis . The following are the main points investigated : ( 1 ) Quantity and quality of coke ; ( 2 ) Quantity of oils boiling below 221 °C . ( gasoline stock) and oils boiling at 221 to 300° C . ( kerosene stock) ; and ( 3) Quantity and quality of gases .

Jan 1, 1922

By John E. Shelton

The growing interest in beryllium as a structural material, and its in-creased use in recent years for atomic energy application, have led both government and industry to express concern over the inadequacy of the beryllium resources in the United States and the free world. Contemplated and proposed uses for this unique material will surpass the capacity of the domestic beryllium mining industry to supply raw material, which is presently extracted from relatively small deposits by hand sorting. The need for a simple beneficiation process for beryl ores has long been recognized by the Bureau of Mines, but to date no single process has proved satisfactory for treating deposits containing a sufficient tonnage of beryl ore to warrant commercial exploitation. As a part of the Bureau's continuing effort to develop an economical recovery process, this report describes flotation research on samples of beryl-bearing pegmatites from the George Roebling mine in Connecticut, and the Colony mine in New Hampshire. The study resulted in two methods of treatment to which the ores responded reasonably well.

Jan 1, 1961

By W. C. Hudson

"The Miami-West Palm Beach belt of silica sand, which may be suitable for the manufacture of high-grade glass, extends 65 miles northward from the neighborhood of Miami to the vicinity of West Palm Beach, The sand presumably originated in the host rocks constituting the oceanward slope of the Appalachian Mountains and the Piedmont Plateau of Georgia and the Carolinas. The sand now lies in a long, narrow, and probably thin belt that forms a dune-capped terrace marking a previous stage of submergence. The highest dune crests appear to be no more than 30 feet above sea level, and the water table is about 10 or 15 feet below the general level of the terrace.The width of the belt in several places is known to be more than a mile, and the thickness of the clean glass sand sampled ranged from 4 to more than 7 feet. Visual inspection and the meager data indicate the existence of bodies of glass sand large enough to supply foreseeable markets.Analyses of three samples indicate that beneficiation would make the sand suitable for the better grades of ordinary and flint glass.The prospective grade and quantity of sand, an available market in Florida for glassware, and the expectation of postwar expansion of the new industry of glass producing justify more detailed exploratory work and beneficiation testing.U. S. Route No. 1, Old Dixie Highway, the Seaboard Railway, and the Florida East Coast Railway, all substantially parallel and usually within a width of a mile or two, run along parts of the belt or between it and the coast. In addition to many streets and unpaved roads, a paved road crosses the belt at right angles about every 5 miles. Numerous towns are situated within or near the belt. Any area selected for a mining, processing, and manufacturing plant would be near a railroad, a highway, and water and also accessible to public utilities.The subtropical climate, famous for its pleasantly warm winters, would preclude seasonal interruption of plant operations."

Apr 1, 1946

By R. H. Harrison, D. R. Douslin

The thermodynamic properties H - H° , (H - H° ) /T , S - Sideal , S - S° Fide al F - F° , (F F° ) /T , and activity coefficient Y for perfluorocyclobutane were calculated as functions of temperatures ( 115.22 ° to 350 ° C) and molal density (0.75 to 6.5 moles / liter ) . Improved analytical and graphical correlating techniques are described .

Jan 1, 1964

By R. V. Ramani, V. T. Burgos, J. A. McClay

Cost System The cost system reported here is a suite of computer programs which incorporates the logic and information flow structure as outlined in earlier chapters. Specifically, computer programs have been devel¬oped to: 1. compute labor, operating, and capital costs, 2. summarize cost and production data, and 3. compute the minimum acceptable selling price for coal. While the cost system can be executed independently, it is de¬signed primarily for use with the Master Design Simulator and there¬fore must conform to the overall system hardware. The computer model is written in Fortran IV for use with the IBM System 360/370 computers as well as with compatible units such as the Univac 1110 and CDC-6600. For ease in error detection and program modification, the model was constructed with a main routine and eight subroutines. The main routine reads and stores the data necessary for the cost computations and calls the subroutines in logical sequence. The subroutines perform the cost computations and data adjustments for reporting purposes. Each subroutine performs the cost computations for its particular com¬ponent of the cost cycle. The program operations are described in the following narrative outline. Control Subsystem As previously described, the main routine is a passive element, reading and storing input data and directing execution to the active subroutines for cost calculations. Figure 10 is a macro-flow diagram

Jan 1, 1975

By Je M. Oh

The Bureau of Mines is conducting research to determine the high temperature oxidation resistance of substitute stainless steels (SS) containing two less strategic elements, Al and Si, instead of Cr. Chromium is considered to be a critical and strategic metal. Although the Cr content was reduced to 8 wt pct, the alloys showed better oxidation resistance than did 304 SS containing 18 wt pct Cr. Specifically, the alloys that contained Fe-8Cr-16Ni with combinations of Al and Si showed excellent oxidation resistance even at temperatures up to 1,000° C. In this study, the effects of the alloying elements on oxidation kinetics and morphology of oxides were investigated using a Cahn Rg electrobalance, scanning electron microscopy, an energy-dispersive X-ray analyzer, X-ray diffraction, and an electron microprobe. Aluminum and silicon additions in combinatin were more effective in providing oxidation resistance than either element was alone.

Jan 1, 1986

To help mine safety and health professionals manage and reduce hazardous noise exposure with a software tool that simplifies the record-keeping and analysis process. Background Hearing loss resulting from overexposure to noise continues to be a problem throughout the U.S. mining industry. Studies indicate that 70%?90% of all miners have a noise-induced hearing loss severe enough to be classified as a hearing disability by the time they reach retirement age. To address this problem, the National Institute for Occupational Safety and Health (NIOSH) developed the Determination of Sound Exposures (DOSES) software program. DOSES is designed specifically for use by mine management and safety personnel to simplify the record-keeping and analysis associated with time-motion studies, making it easier to identify and solve noise exposure problems.

Jul 1, 2009

By Michael J. Brnich

On November 20, 1968, a massive explosion rocked the underground workings of Mountaineer Coal Co.?s Farmington No. 9 Mine in West Virginia. Of the 99 miners who were working in the mine at the time of the explosion, only 21 survived and escaped the mine. This group included eight who were rescued from the Mahan?s Run air shaft. Nearly 40 years after the event, researchers from the NIOSH Pittsburgh Research Laboratory conducted oral history interviews with two of the eight survivors rescued from the shaft. The Farmington No. 9 Mine disaster ultimately led to passage of the Federal Coal Mine Health and Safety Act of 1969 (amended in 1977).

May 1, 2009