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By T. T. Natarajan, Nagy EI-Kaddah

"Numerical simulation of electromagnetic confinement systems generally requires large CPU time due to the strong coupling between the electromagnetic and the free boundary problems. The present paper examines the accuracy and the computational efficiency of the most common numerical schemes used in modeling such systems. Levitation melting was taken as a test case. In this study, a comparison was made between the finite element and surface integral methods for electromagnetic field calculations. The computational efficiency of Lagrange and the modified Hestenes methods for solving the free boundary problem were investigated. The convergence of the Lagrange method was found to be much faster than the modified Hestenes method. It was also found that finite element method not only gives accurate solutions, but faster convergence to the final equilibrium shape than the surface integral method. The applications and the limitations of these techniques in modeling electromagnetic confinement systems will be discussed.IntroductionIn recent years there has been a growing interest in the use of electromagnetic forces for confinement of molten metals as a means to eliminate molten metal contamination during melting and to improve surface quality of cast products. Continuous casting of metal without contact of a mold is now a reality, and is being commercially applied for casting of aluminum slabs /1/, and copper rods /2/. New applications of electromagnetic confinement in melting and casting include containerless melting (Magnetic Suspension Melting) /3/, edge containment in twin roll casting, and meniscus shape control in continuous casting of steel /4/.Modeling of confinement systems involves the determination of the electromagnetic field and the equilibrium shape. These two problems are strongly coupled due to the dependence of the field on the shape of the melt. While significant advances have been made in computational electromagnetics /5/, the application of developed computational techniques to electromagnetic confinement problems is not a simple task. The principal difficulty in using these methods is that the solution domain is not known a priori. due to coupling between the electromagnetic field and the free boundary problems. These two problems have to be solved simultaneously, leading to an iterative solution procedure. As a result, numerical simulation of electromagnetic confinement systems are computationally intensive with computational time at least an order of magnitude larger than the fixed domain problems."

Jan 1, 1994

By John Petty, John Loviza

As a blaster, have you ever had that uneasy feeing in the pit of your stomach as a codes enforcement official drives onto your jobsite? Have you ever needed an ally in a court of law against an unjust damage claim? Have you ever wished for a better and more open relationship with the guys who wear the badges?

Jan 1, 1996

By Hennie F. T. Barnard

Where geotechnical designs are governed by settlement requirements, soil and rock moduli are important parameters for design. This paper reports on a method that was used to utilize dynamic modulus measurements in the field toward pile settlement designs for the proposed Square Kilometer Array (SKA) Project to be located near Carnarvon, South Africa. The project will comprise of over 3000 No. movement sensitive satellite dish structures. The method described in the paper utilizes strain-related modulus degradation across the complete ground profile, starting from measurements of peak particle velocity (and inference to dynamic modulus at small strain) as measured using Continuous Surface Wave (CSW) testing at individual dish positions. This is required due to the very small allowable foundation rotation of 5 arc seconds under the dishes? operational conditions. The strategy of analysis was to conduct an iterative process starting from the measured small strain modulus profile of the ground. The likely maximum pile force for a specific piled foundation option was estimated and a single pile finite element analysis was performed using Plaxis 2D (Version 2010) to estimate the expected ground strain developing along the length of the pile. By assuming the shape of the shear modulus degradation curve with increasing shear strain, the iteration process then converged on a likely degraded modulus profile associated with the single pile and maximum load assumed. This process enabled identifying the pile cap size, pile configuration, pile sizes and pile lengths that would meet the operational movement limits. The chosen pile group configuration was then analyzed using the Repute 1.5 pile group analysis software. The design process and typical results are discussed in this paper.

By Manoj Kumar, Anil Kumar Singh, Prabal Patra, Ashish Agrawal, Souvik Ghosh, Subhashis Kundu, Kamma Ramakrishna Rao, Manish Kumar Gupta, Anindya Sarkar

The slag measurement systems in the cast house are very important. In the conventional method, the slag is granulated in a slag granulation system, and the slag flow rate is measured by the associated belt scale. However, in places where a slag granulation system is not available, the alternate approach is to deduce a theoretical calculation and develop the measurement because the commissioning of such slag granulation requires huge capital and has inherent geographical limitation. However, the theoretical approach suffers from several drifts and is far from the reality. In the present paper, we have innovatively engineered a sensor by designing the stellite-coated thermocouple that can measure the temperature of the slurry and placed it in such a way that the abrasive slag granules do not obstruct it, but we could measure the temperature of hot water, and further based on the thermodynamic approach, the slag flow rate is determined that can be compared with the theoretical approach. This approach of slag rate measurement is cost-effective and long-lasting.

Oct 2, 2023

By W. P. Diamond

The Bureau of Mines has been involved in the drilling of vertical, horizontal, and directional coalbed gas drainage boreholes for mine safety since 1964. In that time, boreholes have been drilled in most of the major coal regions of the United States under a wide variety of geologic conditions. Many of the geologic conditions that occur in the coal measures are detrimental to gas drainage; others may be beneficial. Analytical techniques to determine the gas content of coal samples and evaluate regional trends of gas distribution have been developed. Drilling techniques that maximize the acquisition of coalbed gas data and geologic information have been determined. Although some of the geologic factors influencing the placement and potential success of coalbed gas drainage boreholes have been reported in papers on individual projects, a complete, systematic compilation has not previously been available. The objective of this paper is to pro- vide information on specific geologic factors that should be considered prior to, during, and after the drilling of coalbed gas drainage bore-holes. Many of the commonsense considerations that have been learned through many years of Bureau of Mines experience, but have generally not been reported formally, are included for those who may be considering coalbed gas drainage drilling for the first time, or who have not had the opportunity to encounter a substantial number of geologic situations.

Jan 1, 1982

By Richard F. Link

The objective of this report is to explain a statistical method for the summarization, organization, and classification of multivariate assay and other data from the mineral industry. Multivariate data are those characterized by several measurements at each data point, such as assay data from a mixed metal mine, or blast furnace data. A specific method of linear discriminant analysis, the Mahalanobis d2 procedure, is explained, starting from elementary principles; the d2 procedure enables many measurements at many data points to be studied by investigating the interrelationships among the data. The relation of linear discriminant analysis to other statistical methods for treating multivariate data, in particular the eigenvalue technique of factor analysis, is also explained. Example analyses are made on data from the Frisco mine, San Francisco del Oro, Chihuahua, Mexico. The data comprise assay values for silver, lead, copper, and zinc taken at some 19,000 sample points distributed into 91 groups.

Jan 1, 1967

By Tobias W. Goodman, George N. Aul, Joseph Cervik

The Bureau of Mines conducted research to degasify a virgin block of coal in the Beckley Coalbed using long horizontal holes drilled in an array from the bottom of a ventilation air shaft. Eight horizontal holes and an in situ pressure hole were drilled in a radial pattern to depths ranging from 418 to 910 ft (127 to 277 m) and 205 ft (62 m), respectively. The investigation showed the shaft was in a basin saturated with water, which resulted in low gas flows from holes. The in situ pressure at 200 ft (61 m) into the coalbed was 79 psig (544.6 KN/m2). The aver- age gas and water flows for the eight holes were 94,100 ft3/day (2,665 m3/day) and 13 gal/min (49.3 l/min) . After 514 days of degasification, 18.7 million ft3 (0.53 million m3) of gas had been drained. Methane face emissions, which were measured as a section advanced toward the shaft, were reduced about 77 pct, emphasizing the value of drainage by this technique. All holes were grouted before the area around the shaft was mined.

Jan 1, 1982

By Dale R. Andrus

Why is there such an increased thrust toward positive multiple use land management and where will it lead? History and purpose of the mining law of 1872. John Marshall discovered gold at Sutter?s mill near Coloma, California, on January 19, 1848, and utter chaos resulted. The great migration of people to the undeveloped western lands had begun. Prior to this discovery, copper, lead, and iron had been the minerals for which the laws were made. With this discovery of gold on the public domain, it became apparent that congressional legislation was necessary. This became even more apparent as each of the numerous mining districts which were springing up in California, and elsewhere in the west adopted local miners' customs to regulate their activities. Although these early miners acted under mining district rules and in some cases state regulations, they were, in reality, appropriating minerals without sanction of federal law.

Jan 1, 1970

By M. K. Larson

"Specialized numerical modeling codes have been developed over the years to estimate ground stresses during the excavation of coal in underground mines. One of these tools, MULSIM, a displacement discontinuity boundary element code, was last developed by Zipf into a version called MULSIM/NL [USBM 1992a, 1992b]. The code was used frequently in years past, but closure of the Bureau of Mines in 1996 marked the beginning of a pause in its development. A similar tool with distinctly different treatment of overburden idealization, LaModel, was subsequently developed [Heasley 1997] and largely displaced MULSIM/NL in the literature. However, recent work modeling deep western longwall coal mines [Larson and Whyatt 2013] has demonstrated that MULSIM has distinct advantages for regions with relatively stiff and strong overburden. This work required that MULSIM be revived and updated into a version called MulsimNL/Large. Updates include larger array sizes, greater precision, greater number of materials, and the addition of a five-point, six-segment pillar load/displacement model that provides the user a more flexible coal-strength model allowing hardening and softening before a final residual strength. MulsimNL/Large has the ability to calibrate to large load transfer distances observed in some western U.S. coal mines that appear to be caused by strong, massive units in the overburden and/or floor of a coal mine. Also, it provides the ability to calibrate gob stiffness to simulate measurements or estimates of overpanel weight distribution between gob and abutment, while still maintaining load transfer distance with minor adjustments. MulsimNL/Large can easily implement material strengths calculated from various pillar strength models. The five-point model gives MulsimNL/Large the ability to easily simulate pillar behavior that is extracted from detailed pillar models, such as FLAC3D. MulsimNL/Large or similar approaches should be considered for evaluating mining layouts where stratigraphic conditions are known to cause overpanel weight to transfer to an extent significantly longer than the empirical method widely used to calculate load transfer distances in the U.S. [Peng and Chiang 1984; Mark 1987; USBM 1990]."

Jan 1, 2015

By W. K. Ting, A. Hasan

Mine stope is typically backfilled with cemented paste backfill, which provides a regional underground stability and also a reduction of aboveground tailings accumulation. During backfilling, a phenomenon known as arching occurs and affects the stress distribution of the cemented paste backfill. The change in temperature due to uncontrolled heat transfer from the surrounding rock mass and/or generation from hydration process complicates the stress distribution development of cemented paste backfill. This paper presents results of the investigation on the effects of hydration to cemented paste backfill behaviour when backfilled into a narrow wall model using uncemented paste backfill as controlled sample. The parameters considered include backfill type (cemented paste backfill vs uncemented paste backfill), curing temperature (30°C–60°C), and stress evolution during pouring, consolidation, and curing stages. Results show that uncemented paste backfill re-establishes arching effects more readily, with lower peak stresses and greater stress relaxation than cemented paste backfill, of which its behaviour is significantly influenced by hydration under elevated temperatures. The main outcome of this work is that hydration critically controls the stress-temperature response of cemented paste backfill, and the balance between hydration-driven strength gain and stress relaxation can be leveraged to optimise backfill mix design for safer and more efficient stope filling.

Jan 30, 2026

By Frank E. Chase

Sacrificial entries, roof slotting, and other tactics have been used to combat high horizontal stresses during roadway development in U.S. coal mines. In Australia, the "pillar extraction on the advance" mining method has been successfully employed as a horizontal stress control technique. The concept of advancing and relieving mine workings through pillar extraction developed from observations that some mines experience difficult ground conditions when advancing and retreating the first panel in a new reserve. However, conditions dramatically improve in subsequent panels. Apparently, the creation of a gob area stress relieves the adjacent panel workings. After much debate and close scrutiny, the first U.S. roof control plan to advance and relieve was approved in 1998, for the Sargent Hollow Mine in Wise County, VA. The major concern was that this mining practice places section personnel inby of the gob. The tentative approval permitted barrier pillar slabbing and removal of the adjacent development pillar during panel development. The intent of the plan was to provide a "stress shadow" for the advancing faces and outby workings to reduce the excessive number of roof falls. Sargent Hollow successfully extracted their first panel by pillaring on advance and retreat mining using posts. Mobile roof supports were employed to extract pillars while advancing the second panel. This paper summarizes Sargent Hollow Mine's experiences with the advance and relieve mining method.

Jan 1, 1999

By Charles Sabine

The 27,960-acre Newberry Mountains Wilderness Study Area (WSA) is located in the Mojave Desert, 17 miles east-southeast of Barstow. In 1983, the U.S. Bureau of Mines, in conjunction with the U.S. Geological Survey, investigated mineral resources of the area as part of the wilderness review process. The Newberry Mountains are underlain by Paleozoic metamorphic rocks, Mesozoic plutonic rocks, and Tertiary volcanic rocks. Eleven mines and prospects were examined. Of the seven sites within the WSA, only the Northrup Prospect is mineralized. Only a few tons of manganese-bearing rock, containing 49% manganese oxide (MnO), are exposed, but exploration may disclose larger deposits. The Azucar Mine, a past producer of gold, is the only site examined outside the area that appears mineralized. Sample data from quartz veins exposed at the surface do not indicate that resources are present; however, the occurrence could not be fully evaluated because underground workings were not accessible. Sand, gravel, and stone are plentiful in the WSA, but alternate sources outside the WSA are available.

Jan 1, 1985

Underground mining has the potential to be one of the more dangerous industries in the United States and the world. Following recent disasters in Sago, WV; Darby, KY, and Crandall Canyon, UT, the mining industry was reminded of the need for a system to allow trapped miners awaiting rescue to survive following a disaster. To address this need, Battelle has developed a Mine Barrier Survival System (MBSS) that surpasses all current technologies and sets a new standard for keeping miners alive in the event of a fire, flood, explosion or collapse. The MBSS creates a temporary refuge for miners who cannot escape by using inflatable barriers and a post-fire atmosphere scrubbing system to define the ?safe haven? and remove CO2 and CO while replacing oxygen and providing heat. Current personal-protective systems in use are designed to provide breathing air for only a few hours when, realistically, it may take days for rescue teams to reach trapped miners. Battelle?s MBSS is designed to aid up to 15 miners for four days.

Jan 1, 2008

By Fredrick D. Palmer

U.S. ENERGY: PUTTING PEOPLE FIRST Assessing Goals, Needs and Resources ?Decision-makers must balance the needs of average Americans with the need for: ?A strong economy ?A clean environment ?A secure nation ?Events of recent years ?terrorist acts, multiple energy crises and a global focus on sustainable development ?magnify the need to balance these principles ?Coal ?domestic, abundant, affordable and increasingly clean ?meets these needs like no other energy source

Jan 1, 2003

By Gennaro G. Marino

Site conditions at several shallow room and pillar mines in Illinois are described and compared with the charac¬teristics of the subsidence profiles at the ground surface. The shape and magnitude of the subsidence profiles were found to be closely related to the thickness of the soil and rock over-burden the percent extraction of the coal, and the shape of mine pillars. The room and pillar mines were located at a shallow depth (from 112 to 220 ft), beneath flat to gently rolling terrain. Thickness of the coal seams ranged from 5 to 9 ft and at all sites was underlain by underclays. This information has been developed in order to improve techniques for evaluating the subsidence potential at sites within the Illinois coal basin. he results presented form a small portion of the work carried out by the University of Illinois with Illinois Abandoned Mined Lands Councils and the U. S. Bureau of Mines at the Minneapolis Research Center in Minnesota (Marino and Mahar, 1985). Presented in the paper are the modes of mine failures observed for Illinois room and pillar mines, an overall summary of the site geologic and mining condi¬tions, case histories of each mode of failure, a comparison of sag profiles, and then an empirical relationship between the site conditions and the maximum sag subsidence. The most ideal case histories are presented to illustrate fundamental behavior. A brief of the Paper is given in a summary and conclusions section.

Jan 1, 1984

By Jessica Smith

Jan 1, 2009

By John M. Karhnak

The Bureau of Mines has a long history of research in Ground Control. For many years, this work was done at Bureau facilities by Bureau researchers. As the tiles changed, however, the area of research interest broadened, and additional methods of implementation, such as con- tracts, were added. 'Ibis paper outlines the organization, goals, and methods of implementation of the Bureau Ground Control Program, along with procedures for project selection. This program organization is followed by several specific examples of Bureau research that will be soon ready for use in the mines.

Jan 1, 1981

By J. P. McGeer

"With the ever-increasing flood of new science and technology has come a new approach to design. The combination of these factors has produced an ever-accelerating pace of materials substitutions.Examples to illustrate the points made above will be given. An overview of the current new materials fields will follow. Finally, the particular nature of the challenge for Canada will be discussed. IntroductionThere are a number of forces currently at work which make it mandatory that the Canadian resource sector re-examine its strategies and policies. The author thinks there need to be very significant changes in the business plans of Canadian mineral processing corporations. Current changes in our environment demand such a reaction.The changes in our environment include more rap id substitution of materials; a significant alteration in design philosophy; the global economy; and market saturation and market diversification in dev eloped countries.This paper will cover the changes and illustrate how they will affect the Canadian resource industry. It will show some of the ways that Canadian corporations are reacting to maintain profitability. Finally, some policy issues will be considered"

Jan 1, 1988

By F. P. Yungwirth

"IntroductionTrout Lake Mine is located about 5 km north of the Hudson Bay Mining and Smelting Co., Limited complex at Flin Flon, Manitoba. The mine was brought into production in 1982at the onset of a severe recession in the base metal market. The mine is operated as a joint venture with HBM&S, MMR and SMS.During the first several months of operation it became evident that there were opportunities to reduce costs at the mine significantly, and a productivity improvement subcommittee was formed to make recommendations. The first committee met in January, 1983 and consisted of the mine manager from Hudson Bay Mining, a geological expert and a maintenance expert from Outokumpu Oy, Finland, and a mine manager from Granges, Sweden.Recommendations from this committee were implemented during 1983 and a new subcommittee was constituted in 1984 to continue the work begun the previous year. The committee remains as constituted in 1984 and meets quarterly.The committee consists of M.A . Kirby , manager - Flin Flon Mines, HBM&S; Gustav Hoberstorfer of Mindelco , a Swedish mining consultant retained by Granges; Eero Laatio, mine superintendent of Keretti Mine at Outokumpu Oy in Finland; and Bob Bray, a mining consultant retained by Manitoba Mineral Resources.Many productivity improvements made in the operation are attributed to the work of this committee and other experts retained at various times throughout the mine life."

Jan 1, 1988

Maximising margins in today's competitive international commodity markets demands superior productivity. This requires more than simply selecting the best equipment. It requires efficient production and commercial processes together with management systems recognised as international best practice. This paper introduces an integrated way of working that includes management systems for successfully changing work practices and attitudes, developing managers and increasing accountability. It provides an improvement methodology that includes systematic involvement of people in true continuous improvement of processes for maximising productivity and safety while minimising costs. Even though the principles are proven in all industry sectors worldwide, they are not always used correctly. This paper provides examples of traditional performance measurement systems to show how managers miss opportunities to control and improve both production and supporting service processes. It also describes the basic methodology for correct use of the principles and provides examples of correct implementation of modem systems in mining. The charts from actual mining case studies will be elaborated upon in the conference presentation. This paper's main aim is to provide background material for the presentation by introducing integrated principles for building best practice management systems for superior productivity and safety - for higher margins.

Jan 1, 1996