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By A. W. Henderson

The growing importance of halide metallurgy for preparing high-purity metals has stimulated research to extend halogenation reactions to the direct extraction of metals from low-grade sources. This Bureau of Mines investigation involves a pioneering study of chlorination reactions in the presence of a fluorine donor. Tin slags containing tantalum and columbium and a zircon concentrate containing a relatively high ratio of hafnium to zirconium were studied. Direct chlorination of these materials at 500° C. yields only a 5-percent conversion of tantalum and columbium or zirconium and hafnium to anhydrous chlorides. This investigation showed that small additions of calcium fluoride to the reaction increased the recovery of tantalum and columbium to 95 percent and the recovery of zirconium and hafnium to 27 percent. These results were achieved with ratios of calcium fluoride to mineral or slag of only 0.2. Silica, the major impurity in the materials studied, was found to be converted to silicon tetrafluoride during chlorination in direct proportion to the quantity calcium fluoride added to the charge. However, large additions of calcium fluoride decreased the volatility of the resulting halides of tantalum, zirconium, and hafnium. Smaller amounts of calcium fluoride also favored recovering minor metal constituents in the zircon concentrate (uranium, thorium, and rare earths).

Jan 1, 1962

Various aspects of judgment and decision-making are key themes in this book. The model presented here serves as a loose structure for the chapters that follow this one. The notion of a model is introduced because growing research interest in the subjective aspects of group and individual behavior has led to a debate over whether judgment is a skill that can be understood scientifically. A related point of contention is whether such an understanding could lead to the development of methods for estimating people's ability to make good decisions during an emergency. There is some literature that supports the potential usefulness of this approach. However, little agreement seems to have been reached on how to define and operationalize even those basic concepts necessary to assess the soundness of decisions from within their environmental and group contexts [Jensen and Benel 1977; Godden and Baddeley 1979; Baumann and Bourbonnais 1982; Brecke 1982; Stone et al. 1985]. A look at the real-world process is clearly needed. The need to attempt a better understanding of judgment and decision-making properties stems from those occasions in the existence of an organization when there is a lot at stake. The process of decision-making (which is part of the exercise of judgment) has been analyzed in situations such as corporate takeovers [Janis and Mann1977], military combat [Begland1979], clinical emergencies [Baumann and Bourbonnais 1982], and aviation events [Billings and Reynard1984]. The fundamental assumption of these analyses is that, while there are untold successes, there are also notable numbers of failures resulting from decisions that can be ascribed to one or more errors in judgment. From a cognitive perspective, any person engaged in decision-making (either alone or in a group) is actively involved in a process characterized by certain elements. These were mentioned in chapter 1, but are reiterated briefly at this point: (1) detection of a problem, (2) definition or diagnosis, (3) consideration of available options, (4) choice of what is perceived as the best option given recognized needs, and (5) execution of the choice based on what has transpired [Flathers et al. 1982; Baumann and Bourbonnais 1982]. At any moment in this process, there are factors at play that have a large impact on one's ability to solve complex problems in a limited time: (1) an internal state [Hedge and Lawson 1979] is the sum of a person's psychomotor skills, knowledge, attitudes, etc.; (2) uncertainty [Brecke 1982] is caused by faulty or incomplete information received from the external environment; (3) stress [Biggs 1968; Jensen and Benel 1977] is generated both by the problem at hand and any background problem that may exist; and (4) complexity, as it is used here, refers to the number of elements involved that must be attended to. These variables are depicted in figure 5.1, and their relationship to each other and to an outcome is indicated. This schema is designed to suggest interaction, because while the judgment and decision-making process may be conceptualized as discrete stages, experience tells us that this is not the way people function in real-world situations.

Jan 1, 2000

By David C. Peters, Robert S. Crosson

A method of error analysis has been applied to the location technique of non-linear least squares iterative inversion in order to evaluate the resolving power of several seismic array configurations with various assumed earth models and errors and inaccuracies in arrival times. The results obtained demonstrate that lateral accuracies of location are improved significantly when the depth of the miner is known. Lateral location to within 100 feet appears achievable in many instances. If it is possible to refine earth models significantly beyond what has normally been assumed in this work by the use of on-site data, or if the mine is shallow (300 feet or less), accuracies of-about 30 feet or so may be attainable. Inaccuracies in earth models of about 5% are found to contribute much more heavily to these location inaccuracies than errors of a few milliseconds in picking arrival times; however, arrival time errors of 15-20 ms or above will dominate these model inaccuracies. The expected accuracy of location is found to fall off very rapidly as the miner moves outside the array. The strength of this effect depends markedly upon the geometry of the array configuration and can be reduced by careful design. Also, as the size of the array is increased, expected location errors within the array are not altered much, but continue to match the error associated with the smaller array over a larger area (assuming that all stations can still pick up the miner's signals). Better location accuracy, especially with respect to depth control is achievable in an earth where the velocity is depth-dependent (increasing with depth) than in one which is homogeneous. This is an advantage since the

Jan 1, 1974

By Jack C. White

As part of an investigation of the production of alumina by the nitric acid leaching of kaolinitic clay, the Bureau of Mines designed, built, and tested a fluidized-bed system for the calcination of aluminum nitrate nonahydrate to alumina, while recovering nitric acid. The calciner consisted of an 8-in-square by 36-in-tall vessel containing 18 in of fluidized solids. Molten aluminum nitrate, sprayed directly into the fluidized solids, formed sandy, granular alumina by growth of successive layers on fluidized particles. Solids were fluidized in a dense bed at temperatures of 250° to 500° C with steam, air, or mixtures thereof. Decomposition of nitrate ranged from 4 to 10 pet during single-pass steam or air fluidization, respectively. Alumina dust losses and low throughput are significant unsolved problem areas.

Jan 1, 1982

By N. N. Moebs

The Bureau of Mines air-sealed a 77-acre) above-drainage coal mine to evaluate sealing as a means of reducing the acid and metallic salt contents in drainage from abandoned mines. An approximate reduction in acidity of 150 ppm (equivalent to 193 pounds per day) and in iron of 98 ppm were directly attributed to sealing. The topographical, hydrological, and other factors involved in air-sealing are discussed, and the construction used to seal the mine is described.

Jan 1, 1970

By R. E. Head, Virgil Miller

"INTRODUCTIONRecent investigations at the Intermountain Experiment Station of the Bureau of Mines at Salt Lake City indicate that metallurgists have given little attention to the occurrence of jarosite minerals in the oxidized ores of lead and silver. These investigations have also emphasized the importance of knowing when these minerals occur in the oxidized ores, especially those containing lead, silver, and gold, as their presence is a material factor in selecting a suitable kind of treatment. Since the question of the occurrence of jarosites in oxidized ores has come to the attention of the Bureau of Mines, investigation has indicated that plumbojarosite and argentojarosite are quite common. These two minerals appear to be widely distributed and probably escaped recognition by persons who had attempted to treat certain oxidized lead ores in which the jarosite minerals represented a material portion of the metal content.Consideration of the physical characteristics of the jarosites also indicates that in many cases failure to treat some of the oxidized lead ores with success has been directly due to the fact that the greater portion of their lead and silver content was present as plumbojarosite and argentojarosite. The data and the description of these minerals given in the body of this paper indi¬cate that attempts to recover lead and silver from ores in which appreciable amounts of the metals occur as plumbojarosite and argentojaeosite would be unsuccessful if confined to gravity methods of concentration. There are un-doubtedly considerable tonnages of oxidized lead ores in the various mining regions of this and other countries, and it is quite probable that in some of these ores the metal content of lead and silver may be largely anglesite (lead sulphate) and cerussite (lead carbonate) but that they will also contain cerargyrite (silver chloride), argentojarosite, and plumbojarosite. The treatment of such ores therefore presents an important problem, since a product is discarded from ores from which the recoveries of lead and silver have been below 70 per cent which is probably too low-grade to warrant aftertreatment by any process now in use."

Apr 1, 1928

By H. W. Kilau

The U.S. Bureau of Mines examined the wettability of bituminous and subbituminous coals before and after exposure to ambient air atmosphere, as part of an ongoing project investigating the coal-wetting abilities of surfactant solutions intended for the suppression of dust during coal mining operations. Exposure periods were generally 7 days or less, and the changes in wetting response were measured with a capillary penetration apparatus. Wetting solutions tested included a nonionic surfactant, two anionic surfactants, and pure distilled water. After exposure, higher ranked bituminous coals treated with nonionic surfactant solution and pure water showed increased wettability, but lower ranked subbituminous coals showed decreased wettability. With the anionic surfactants, the coals demonstrated opposite responses. The wettability changes appeared to be related to the coal moisture content. These changes may be amplified by specific, but incompletely understood, interactions between surfactant polar groups, absorbed water, and the coal surface.

Jan 1, 1989

By H. D. Jacobs

The Bureau of Mines developed a concentration method to upgrade and utilize marginal natural or direct-shipping iron ores and fine-grained lean iron ores. Presently these ores receive little beneficiation and accordingly have low iron-silica (Fe-Si02) ratios. Ore samples were roasted with equal weights of solid reductant at 1,100° C for 1 hour to metallize the iron and for an additional hour at 1,200° C to promote grain growth. Concentration was effected by crushing and screening techniques and/or wet magnetic separation. Sized concentrates (minus 4 plus 35 mesh) derived from crushing-screening processes contained from 80 to 85 percent iron that was 90 percent metallized. Iron-silica ratios as high as 12:1 and iron recoveries from 75 to 94 percent were obtained. The sized concentrates were judged suitable for use as blast furnace feed. Minus 200-mesh metallized concentrates derived from roasted minus I-inch plus 8-mesh ore fractions and magnetically concentrated contained 90 percent Fe and 4 percent or less Si02, chemically qualifying them as feed for electric furnaces. Roasting minus 8-mesh ore with hydrogen, then magnetically concentrating it, produced iron concentrates containing 57 percent to 67 percent Fe and 3.6 percent to 8.4 percent Si02. The concentrates having Fe-Si02 ratios ranging from 8:1 to 12:1 were considered adequate for use as blast furnace feed. Overall iron recoveries for the 12 ores tested ranged from 56 percent to 94 percent with an average iron recovery of 86 percent.

Jan 1, 1969

By T. E. Gray

This report describes the preparation characteristics of the significant coalbeds in Boone County, W. Va., as determined by the Bureau of Mines. It is one of a series describing the coals suitable for producing metallurgical coke, either as mined or after beneficiation. Over 6.3 million tons of coal was produced in Boone County, W. Va., in 1959, of which almost 5.5 million tons was mechanically cleaned in eight preparation plants. On December 31, 1959, it was estimated that almost 8 billion tons of coal remained in the county in beds 24 inches or more in thickness. Thirteen samples were collected from nine coalbeds and washability tests were made on these samples.

Jan 1, 1961

By George S. Koch

Several methods of calculating ore grades by diamond-drill sampling in the Homestake mine, Lead, S. Dak., have been evaluated by statistical analyses of assay data. The natural distribution of gold particles, partly masked through sampling and assaying procedures, is probably lognormal. As a consequence of the gold particles being clustered rather than randomly distributed within the ore bodies, (1) more mine samples are needed to obtain a specified precision of mean grade than the number predicted by the standard-error-of-the-mean law; (2) the variance of gold values is not inversely proportional to sample volume, and, therefore, small-diameter drill core yields samples nearly as good as larger diameter core; and (3) sampling at 5-foot intervals provides nearly as good results as sampling at shorter intervals.

Jan 1, 1971

Objective As mines become safer and disasters fewer, a time may come when no employees in the mining industry have any practical experience in managing a mine emergency. To fill an emerging gap in mine emergency response training, a multidisciplinary team of researchers and computer programmers from the NIOSH Pittsburgh Research Laboratory has developed an intervention for mining personnel who would be in leadership positions in the command center during emergencies. It is called MERITS, a computer-based emergency simulation exercise. MERITS is short for "Mine Emergency Response Interactive Training Simulation." It provides trainees an opportunity to gain command center experience during a simulated underground coal mine emergency. MERITS allows trainees to practice information gathering, situation assessment, decision-making, and coordination skills without risk to personnel or property. Individuals representing mine emergency response personnel, various State safety officials, and private mine management from three States have participated in MERITS training. What Is MERITS? MERITS is an extension of previous work that compiled a knowledge base relevant to mine disaster management via interviews, analysis of literature, reviews of past events, and observations of mock mine disasters. Findings from prior research found a need for an alternative method of command center training. This new computer simulation is being used to train emergency command center personnel to effectively manage an underground mine fire. Modeled after training simulations developed for other industries (e.g., to address nuclear accidents, chemical spills, evacuations, etc.), MERITS simulates underground and surface events related to the disaster. It exposes the user to events that typically occur during a mine emergency, such as lack of information and miscommunication. It also presents trainees with issues that must be addressed, such as making provisions for briefing news media and victims' families, ordering needed supplies, interfacing with Government enforcement agencies, and housing mine rescue teams. The outcome of the scenario is determined by the users' decisions and their emergency response plans. Field Results Field testing of MERITS was conducted with eight full-day training sessions at four different locations in Colorado, Pennsylvania, and West Virginia. These field tests benefited from the knowledge and experience of State of Pennsylvania inspection officials, representatives of the United Mine Workers of America(UMWA), and private mine management who served as trainees for the MERITS training sessions. Trainees self-reported an average of20 years of work experience in the mining industry. All trainees had participated in Mine Emergency Response Development (MERD) training exercises, and many had been involved in real mine emergencies. Trainee evaluation of the MERITS program is summarized below: •Twenty-six of the 27 trainees believed that the MERITS simulation helped them know how to prepare for a real emergency. •Twenty-five of the 27 trainees believed that the storyline for the MERITS simulation was either "very realistic" or "realistic." •All 27 trainees believed that the MERITS simulation helped them learn how to better handle a real emergency. •None of the 27 trainees stated that they were bored during the simulation. After the initial field tests, MERITS was refined and retested during training sessions for individuals from State agencies, the UMWA, and private industry. Mining personnel from underground coal and underground stone mines participated and responded positively to the learning experience. Technology Transfer Industry introduction to the MERITS program will occur throughout 2002. MERITS presentations at the Joseph A. Holmes Safety Association National Meeting in Virginia Beach, VA, in June.

Jun 1, 2002

By Ronald D. Hill, Elmore C. Grim

Sediment is one of America's greatest pollutants. More than a billion tons of sediment reach the major streams of the United States annually(l). Damages are reflected in the reduced carrying capacity of streams, clogged reservoirs, destroyed habitat for fish and other aquatic life, filled navigation channels, increased flood crests, degraded facilities for water-based recreation, increased industrial and domestic water treatment costs, premature aging of lakes by enrichment of the water with silt-carried fertilizer that promotes algae growth, destroy crops, and reduce productivity of flood plain soils. Erosion and sedimentation are natural processes that are usually gentle actions releasing controlled amounts of silt from watersheds to receiving streams. Surface mining activities accelerate these natural processes and short duration, high intensity storms can become a violent force moving thousands of tons of soil in a brief period of time. Cover is a very important factor. With the removal of ground cover, water moves across the denuded area on its own terms picking up soil particles as it flows and leaving gullies behind. The susceptibility of strip-mined land to erosion depends on: 1.Physical characteristics of the overburden 2. Degree of slope 3. Length of slope 4. Climate 5. Amount and rate of rainfall 6. Type and percent of vegetative ground cover. By development of erosion and sedimentation control plans before disturbance of the area, many of the detrimental effects of strip mining can be prevented.

Jan 1, 1974

This Part describes a mine pager phone to public telephone interconnect sys tem that permits mine paging telephones to be selectively interconnected with the public telephone system, as illustrated by Figure 1. This interconnect concept was first conceived and demonstrated in breadboard form by H. E. Parkinson of Industrial Hazards and Communications, PMSRC, as one means for providing improved emergency and off-hours communications. The third-generation prototype unit described in this Part was designed and fabricated by Arthur D. Little, Inc. This unit is a small desk-top or wall-mounted unit that connects directly to both the public telephone line and the mine pager phone line, and requires no modifications to either the public dial telephone or mine pager phones. As part of this task, ADL also built, under a very compressed time schedule, a second-generation prototype unit suitable for reliable demonstration of the interconnect concept during the Bureau's technology transfer seminar on mine communications in March 1973. * A major objective of the design of the third-generation unit described in this Part was that it be compatible with present mine pager phone systems utilizing DC voltage on the mine phone line to activate the phone loudspeakers. Therefore, this unit was designed to operate in a push- to-talk, push-to-listen mode that accommodates the inherent design differences and operation modes of the mine phones of different manufacturers. Though this push- to- talk, push- to-listen mode of operation may seem slightly unusual at first sight, we have found it is easily learned by new users. However, mine phone manufacturers wishing to expand their product lines with such an interconnect system will probably find it to their advantage to customize the design of this system to their particular mine phones, thereby utilizing the unique attributes offered by their individual product lines. This customization should not be difficult, and Section III below suggests some of the features that can be easily added to future designs. Detailed parts lists and circuit schematics for the present third-generation proto- type system can be obtained from the system manual submitted to PMSRC and placed on public file.

Jan 1, 1974

By Neil B. Young

Carbonate minerals constitute a major fraction of the oil shale in Colorado's Green River Formation. Quantification of carbonate minerals is important for the characterization of oil shale, particularly because of their thermal activity in production of oil from shale. The carbonate minerals found in this oil shale are nahcolite (NaHCO3), dawsonite [NaA1(OH)2CO3], dolomite [(Mg1-xFx)Ca(CO3)2], calcite (CaCO3), and ferroan [(Mg1-xFex)CO3]. Although carbonate minerals can be removed by acid extraction from the balance of the oil shale, direct determination of carbonate minerals is complicated by the occurrence of the same cations in more than one mineral. A method for assigning the acid-soluble cations to the individual carbonate minerals was developed from two assumptions based on oil shale geochemistry: (1) Calcite and ferroan do not occur together, and (2) the ratio of iron and magnesium is the same in dolomite and ferroan. These assumptions were tested by the Bureau of Mines by applying the technique for assigning cations to 219 samples from the saline section of the formation. The reported carbonate mineral amounts were compared statistically with X-ray diffraction peak heights, verifying the cation assignment method.

Jan 1, 1975

By N. C. Tomoeda, W. D. Bensema, J. W. Adams

Measurements of surface magnetic field noise were made at various locations over the Geneva Coal Mine near Price, Utah, on June 12, 1973. The locations selected were on the surface over emergency locator beacons underground at depths between 350 meters (1150 ft .) and 488 meters (1600 ft .) . The surface terrain where these measurements were made was mountainous, and access was difficult. There were no power lines within several miles, and the weather was clear; therefore, the magnetic noise levels were about as low as will normally occur. Results of measurements of distant sferics indicate rather sharp cutoff frequencies below which broad- band, impulsive noise is attenuated. The mechanism of propagation for this noise above the daytime cutoff frequency of 3500 Hz and the nighttime cutoff frequency of 1700 Hz is deduced to be a waveguide formed by the D or E layers of ionosphere as an upper plane and the earth as a lower plane. The measurement systems used are similar to those used earlier. The technique is to record broadband, analog signals, digitize the data, and use a fast- Fourier transform to obtain spectral plots. This tech- nique is novel in that it can measure simultaneously all magnetic field energy within a limited portion of the spectrum for a limited time, and, after processing, reproduce the events occurring in that time interval in great detail .

Jan 6, 1974

By d&apos, Kathleen J. Amico

THIS SUMMARY appears in Minerals Yearbook volumes I and III, which cover mineral production in the United States, its island possessions, the Canal Zone, and the Commonwealth of Puerto Rico, as well as the principal minerals imported into and exported from the United States. The several commodity and area chapters contain further details on production. A summary table comparing world and U.S. mineral production also is included. Mineral production may be measured at any of several stages of extraction and processing. The stage of measurement used in the chapter is normally what is termed "mine output." It usually refers to minerals in the form in which they are first extracted from the ground, but customarily includes for some minerals the product of auxiliary processing operatons at or near mines.

Jan 1, 1963

By Leon W. Dupuy

"INTRODUCTION Scheelite occurring in tactite at the Black Rock tungsten mine, near Benton in Mono County, Calif., was investigated by the Bureau of Mines in cooperation with the Geological Survey as part of their search for additional sources of supply of strategic minerals authorized under the Strategic Materials Act. 3/4/The work accomplished by the Bureau, and the assays of samples taken are described in this manuscript. The ore found aided materially in prolonging the operating life of the mine during the recent national emergency, supplying much-needed tungsten for war use. ACKNOWLEDGMENTSIn its program of investigations of mineral deposits, the Bureau of Mines has as its primary objective the more efficient utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. The Mining Division, under the direction of Lowell B. Moon, chief, conducts preliminary examinations, performs the actual development work, and prepares the final report. The Metallurgical Division, under the direction of C. C. Ralston, chief, analyzes samples and performs beneficiatibn tests."

Mar 1, 1948

By Ted C. Briggs

Twenty-two compressibility runs were made with helium over the temperature range -5° to 80° C and at pressures to 800 atmospheres. A Burnett apparatus was used. Data from the runs were fitted to a fourth degree polynomial equation of state in the pressure and a weighting factor of Pr-3/4 was used. All data for a particular isotherm were treated simultaneously. A temperature function was found to represent the parameters B and C. Compressibility factors determined by this investigation are believed to be accurate to better than 0.05 percent.

Jan 1, 1970

By J. E. Zeilinger

This Bureau of Mines report describes the preparation characteristics of the significant coalbeds of Clarion County, Pa. Of the 15 samples collected, 1 was of metallurgical quality as received, 4 could be sufficiently upgraded to provide acceptable products, and the remaining 10 samples could not be upgraded to metallurgical quality because their sulfur contents could not be lowered to meet the standard. For steam or power generation, 1 sample was of low sulfur content as received, 1 sample could be upgraded to low sulfur content, and 10 samples could be upgraded to medium sulfur content. The original sulfur content of the remaining three samples can be appreciably reduced by removal of the sink 1.58 specific gravity material; however, these coals would be classified as medium sulfur coals both before and after removal of the sink material.

Jan 1, 1968

By David C. Byrne

From an engineering perspective an ideal industrial noise control solution focuses directly on the actual source of the poise. Eliminating the noise-generating mechanism altogether obviates the need for other noise contra l treatments or hearing protection devices. However, in cases where attenuating the source is not feasible engineering controls must be oriented toward blocking the path that the sound waves travel toward employees. Acoustical enclosures are commonly used as sound path treatments to contain the noise from a machine: alternatively a control room/booth or equipment operator's cab may be used to isolate the worker from the noise. Anyone who has successfully used acoustical enclosures knows that the design procurement, and installation process is deceptively simple. Alt too often First-time efforts fait to account for many of the constraints that can render the enclosure essentially useless. Things that cannot be overlooked include: providing convenient worker access (physical and visual): allowing for proper machine operation/product flow; and supplying fresh air or preventing undue heat or contaminate build-up inside the enclosure. All of these factors must be given careful consideration, otherwise the enclosure will not perform adequately.