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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 Uwe Wilhelm

Pittini Group has contracted Danieli in 2011 for the supply and replacement of the existing EAF at Ferriere Nord Plant in Osoppo. This was a very challenging project: giving the fact that the Meltshop was operating already under very high performance level, there were many elements involved for the project to improve (reduce the amount of charges, promote highest possible chemical energy utilization, allow best optimization on existing transformer power, modification on Drop Out box and Water Cooled Duct, Hydraulic System for EAF, Scrap Bucket design to fit to new EAF with existing loading and transport system, Automation System Review and Upgrade) as well as limitations of the existing installation (limited space, lifting capacity building and cranes and the required solutions for fast shell and roof exchange). All furnace parts, as well as installation engineering, were developed and discussed carefully with the Customer to either provide proven and reliable concepts, but also to define solutions for fast installation/maintenance access and quick exchange for offline turnaround. In the end, from disassembly of existing equipment up to the first heat of the new furnace, only 38 days were necessary. First heat was made on January 24th 2013, on the 6th production day 32 heats where produced at nominal design capacity and 28 days after start up 100,000 t liquid steel have already been produced.

Jul 30, 2018

By Magdalena Regel-Rosocka

Extraction of zinc(II) from hydrochloric acid solutions is discussed. The literature on the extraction of zinc(II) in the presence of iron(III) and iron(II) with various basic and solvating reagents has been reviewed. It was found that tributyl phosphate (TBP) is the best compromise, and permits both effective extraction of zinc(II) and its stripping with water. The process was confirmed in a continuous laboratory mixer-settler circuit.

Jan 1, 2003

Project Located in northwestern British Columbia 70km West of Cassiar Highway Galore Creek Project and Road Access Corridors Designated For Mineral Development in Stikine-Cassiar Land Resource Management Plan (LRMP)Approved in 2000Strong BC Government, local community and Tahltan First Nation Support for Project

May 1, 2006

By Mark S. Stagg, Rolfe E. Otterness, Stephen Rholl

The Bureau of Mines is engaged in research to develop and test high explosive fracturing and rubblization techniques that will enhance ore body permeability and thus increase recovery during in situ mining. The natural permeability of many ore bodies is too low to allow successful in-place leaching. These deposits could be profitably mined if flow rates of leach solutions could be increased. Blasting represents a potentially low-cost and effective permeability enhancement technique.

Jan 1, 1991

Proceedings of the Ninth International Symposium on Techniques for Decision-Making in the Mineral Industry, Montreal, June 1970. The Ninth International Symposium on Techniques for Decision-Making in the Mineral Industry was sponsored by The Canadian Institute of Mining and Metallurgy, McGill University and Ecole Poly technique. The programme included 71 papers on various topics, as follows: Market Analysis and Logistics Planning; Quantification of Geological Variables; Blending; Capital Investment Decisions; Mining; Financial and Economic Analysis; Search for Mineral Deposits; Market Forecasting and Strategies; Operations Research in Process Modelling; Ore Reserve Estimation; Management Information Systems; Optimization and Control of Mineral Processes. In addition to general sessions, a special feature of the Symposium was Executives' Day, which was held to provide top and middle management with a broad understanding of the usefulness of decision-making techniques and their role in the mining organization. Panel Discussions and two keynote speakers provided a review, in non-technical terms, of the areas in which decision-making techniques have proven valuable. The present volume contains 65 papers submitted for publication, along with a complete account of the Executives' Day discussion. It is broadly divided according to the above subject headings. Approximately 550 pages, illustrated. Price: $15.00; $12.00 to students, plus 50 cents for handling costs. Order now from CIM headquarters: Canadian Institute of Mining and Metallurgy, 906-1117 Ste. Catherine St. W. Montreal 110, Quebec.

By Felicia F. Peng

An economic analysis for evaluating coal preparation plants in the Appalachian Region is presented. A complete coal preparation plant which includes multi-streams and/or multi-stages coal cleaning circuits, complete closed water circuits, environmentally acceptable refuse disposal and reclamation systems is used to determine the capital and operating costs. The plant is capable of producing metallurgical grade clean coal or deep cleaned steam grade coal for future power generating plants use. Utilizing a profit maximization as a decision criterion, an optimal yield, and optimal coal clean¬ing circuits, closed water circuits, and disposal and reclamation systems for a given coal characteristic may be selected among the process alternatives by using a process simulation-economic model of the coal preparation plant. A deterministic analysis is used to calculate the discounted-cash-flow interest rate of return (DCFIROR) and project the selling prices, and determine the Return on Investment (ROI) for the cases of 32.65% and 52.74% plant utilization with producing two cleaned products. Sensitivity analyses are performed to quantify the effect of total capital investment, operating cost, run-of-mine cost and yield on an economic criterion-ROI and selling prices. A probabilistic evaluation using the Monte Carlo simulation technique is further made to quantify the risk involved in obtaining the desired profit levels. The results of the economic analysis for a given coal preparation plant configuration and characteristics of raw coal indicates that the selling prices of producing two cleaned products are greatly affected by the change in percent of plant utilization (production schedule), yield, and run-of-mine cost, and total capital cost. The sensitivity analysis also shows that the total capital investments has a three times greater effect on required selling prices than operating costs. The risk analysis shown that the overall economics look very attractive with current coal sale prices and 52.74% plant utilization.

Jan 1, 1979

By McHenry Mosier

This is the fourth progress report in the series on the use of detachable rock-drill bits in the metal mines of the United States. It contains comparative statistics and costs or drilling at eight mines not reviewed in previous reports, comparison of the use of detachable bits at small mines and large mines, a discussion on the life of drill rods, and general conclusions derived from an analysis of the rock-drilling practice at all the mines investigated on this survey. This paper completes the descriptions of operating practice in rock drilling at individual mines. Data on drilling practices at 28 mines are given in appendices I and II and drilling costs are shown in appendix III. Research in the fundamentals of rock drilling, including the use of detachable bits, has been undertaken by the Bureau of Mines in its testing adit at Mount Weather, Va. Reports on the progress off this investigation will be issued when results warrant their publication.

Jan 1, 1937

By G. W. Murrie

A geologic study of the Mary Lee Group of coalbeds in the Black Warrior coal basin was undertaken to examine coal stratigraphy and determine regional trends and extent of the coalbeds. The area investigated encompasses 835 square miles in Jefferson, Walker, and Tuscaloosa Counties, Ala. More than 700 core logs were used to construct a structure map, coal, interval, and overburden isopachs, and cross sections. There is evidence that structure affected sedimentation. Coalbed isopachs indicate the Mary Lee Group was deposited in fluvial-deltaic and low-lying coastal plain environments. The Mary Lee coalbed is the only coalbed which is continuous throughout the area, commonly with two benches which have a combined thickness of 2 to 12 feet. The Mary Lee coalbed changes rank in the basin from high-through medium-to low-volatile coal. The methane gas potential of the Mary Lee Group coals is estimated to be greater than 1 trillion cubic feet. There is an excellent correlation between the orientation of surface cleats with those measured underground in the Mary Lee coalbed. The face cleats roughly parallel the axes of the area's folds and trend northeast-southwest.

Jan 1, 1976

By R. V. Norris

1. INTRODUCTION. THE anthracite coal trade, with a shipment averaging about 70,000,000 tons per year, differs essentially from other coal business, in the fact that the larger sizes, comprising about 65 per cent. of the total, are used almost exclusively for domestic purposes, principally during the winter months; and that for proper combustion close-sizing is imperative, so that eight sizes are made; broken, egg, stove, and nut, known as prepared sizes, and pea, buckwheat, rice, and barley, known as steam sizes. These sizes are made in the regular course of preparation, and but little variation in the natural percentage of each is practicable. Thus it is necessary either to work the collieries intermittently, or to dispose of all the varying sizes in their fixed proportions. Unfortunately, the market does not at all times absorb the coal in proper proportions, and rather than interfere with the regular operation of the mines it has been found economical to provide storage for the excess. While the cellars of the consumers are the great storage-plants of the country, this capacity is not under the control of the trade, except so far as reduced prices during the spring and summer months may tempt the use of this reserve. The same remark applies but with less force to the retail yards, which,, though usually small, store in the aggregate a large amount of anthracite. While every effort is made to utilize to the utmost the individual storage-capacity of the country, there still remains the necessity for taking care of the irregularities of the market by the construction of storage-plants under the direct control of the producers. Such plants are usually the property of the railroads, and are situated at points most convenient from a traffic stand-point.

Jun 1, 1911

By Charles H. Rice

Coal liquefaction processes can be divided into two broad classifications - direct and indirect. Direct liquefaction processes, in general, slurry coal with a solvent and react it with hydrogen under elevated temperature and pressure. Indirect liquefaction is the term applied to processes in which coal is first gasified to generate a synthesis gas of carbon monoxide and hydrogen. The synthesis gas is then converted to various types of liquid fuels by the proper selection of catalyst and conditions. The first experiments on direct coal liquefaction were undertaken in 1933 by Bergius. Development and commercialization of the Bergius concept was accomplished mainly through the effort of I.G. Farben at the Ludwigshafen plant of its subsidiary, Badische Anilin und Soda Fabrik A.G, under the leadership of M. Pier (1). A demonstration plat having an annual capacity of 100,000 tons of coal was built in Leuna, Saxony in 1927. Six years later, Imperial Chemicals Industries, Ltd., commissioned a plant in Billingham, England (2).

Jan 1, 1981

By G. Akdogan, C. Dorfling, L. Bumhira

Hydrometallurgical recovery of rare earth elements from phosphors obtained from end-of-life fluorescent lamps involve leaching followed by extraction of dissolved metals from solution. The similar properties of rare earth elements make selective recovery of individual elements challenging. The aim of the paper was to investigate the extraction of primarily Ce and Tb from a hydrochloric acid leach solution also containing other REEs (Y and Eu) as well as impurity metals (Ca and Al). Batch solvent extraction tests were performed with di-(2-ethylhexyl) phosphoric acid (DEHPA) at various extractant concentrations, pH conditions and organic-to-aqueous ratios. Extraction isotherms and separation factors for the range of conditions tested in the project are presented in the paper. Separation of individual REEs was not possible at the conditions investigated, but a mixed REE product can be obtained in a single extraction stage operated at a pH of 0.5 using 1 M extractant at an O/A ratio of 1; these conditions resulted in complete Y and Eu, 95 % Ce and 99 % Tb extraction with Ca and Al coextraction below 7 %. A better quality mixed REE product can be produced by operating at lower pH and extractant concentration conditions, but this would require a larger number of extraction stages. Keywords: Cerium, fluorescent lamps, phosphors, rare earth elements, solvent extraction, terbium

Jan 1, 2020

By Alvin Kaufman

Geothermal plants are competitive with conventional units. A geothermal plant can produce electric energy for 6.70 mills per kwhr, compared with 6.96 mills for coal, 6.74 mills for oil, and 7.04 mills for gas. These costs include fixed and variable charges. Potential for geothermal power exists in the Western United States, Alaska, and possibly Hawaii. Assuming that the current downward trend in cost per kilowatt of coal will cease and that the relative cost of gas and oil, already trending upward, may rise considerably more, geothermal energy will be utilized where available, in producing electric energy. It will be used in California first because it is directly competitive with gas-and oil-fired installations there. A long-term appraisal is difficult because little is known about the sources of geothermal power and the electric generating capacity which the steam fields will support. However, a market for geothermal steam-generated electricity exists within the Western States.

Jan 1, 1964

By Alvin Kaufman

Geothermal plants are competitive with conventional units. A geothermal plant can produce electric energy for 6.70 mills per kwhr, compared with 6.96 mills for coal, 6.74 mills for oil, and 7.04 mills for gas. These costs include fixed and variable charges. Potential for geothermal power exists in the Western United States, Alaska, and possibly Hawaii. Assuming that the current downward trend in cost per kilowatt of coal will cease and that the relative cost of gas and oil, already trending upward, may rise considerably more, geothermal energy will be utilized where available, in producing electric energy. It will be used in California first because it is directly competitive with gas-and oil-fired installations there. A long-term appraisal is difficult because little is known about the sources of geothermal power and the electric generating capacity which the steam fields will support. However, a market for geothermal steam-generated electricity exists within the Western States.

Jan 1, 1964

By V. Koump, T. F. Perzak, R. G. Olsson

The vate of dissolutioz of carbon in molten Fe-C alloys urns studied by votating- cylindrical g-vaphite sairlples in a stationary crucible containing the melt. The rate of dissolltion was determdined from the change in the bnth co)npositiorz. Alccss-tvansfev coeffi'cients, calcilated with the assurlption that the inte)yacial liquid ulas saturated with carbon, were found to be in agreement with an existing Correlation fov mass transfer jroni votating cylinders. It is corzcllrded tlat, itz the wnge of- Reynolds' numbers itzvestigated (790 to 18,000), the vate of dissolutio of carborz in Fe-C alloys is controlled by tile rate of carbon difirsion from the interface. The dissolution of carbon in molten Fe-C alloys has been the subject of a number of investigations. Most of these investigations have been inconclusive because of poorly defined experimental variables. Two of the more sophisticated studies are summarized below. Dahlke and Knacke' studied the phenomenon by, in part, immersing graphite rods into 0.5 pct carbon-steel for different lengths of time. Since the experiments were conducted in air or in CO atmospheres, the melt was strongly agitated by gas evolution. It was concluded that the change in bath composition as a function of immersion time was in agreement with the assumption that the dissolution process was transport-controlled. The hydrodynamic conditions in these experiments, however, were not well-defined and gave no indication of the nature of the dissolution process at higher fluid velocities. In a recent study Shurygin and ruk investigated the dissolution of carbon in molten Fe-C, Fe-Si, Fe-P, and Fe-Ni alloys. Small graphite disks were rotated in a crucible containing molten alloys under such conditions that only the lower face of the disk was exposed to the melt. The results of this investigation indicate that, over the range of velocities (100 to 1000 rpm) and bulk liquid concentrations (0.7 to 4.5 wt pct C) considered, the dissolution of carbon in the iron alloys is limited by the diffusion of carbon from the interface to the bulk liquid (a transport mechanism). For the particular geometry used by these authors, exact analytical solutions of hydrodynamic and diffusion problems are aailable. Hence the experimental results obtained by Shurygin and Kryuk permit the evaluation of diffusion coefficients of carbon in the four systems investigated. In the present investigation a series of experiments were conducted in which the rate of dissolution of carbon in Fe-C alloys was measured under conditions which permitted wide variation of the fluid velocity and the carbon concentration of the bulk liquid. Graphite cylinders were rotated at different speeds in a stationary concentric crucible containing various molten Fe-C alloys. THEORETICAL DEVELOPMENT In general, the resistance to mass transfer from a solid interface to a turbulent liquid is assumed to reside in a laminar boundary layer adjacent to the interface. If it is also assumed that the diffusion coefficient is independent of concentration, the steady-state rate of dissolution for the case of arbitrary liquid and solid densities can be obtained from the integration of the equations of continuity. The derivation is similar to that used by Lommel and chalmers4 for the case of pl = ps. The solution, expressed in terms where N = rate of diffusion of the solute from the interface. Exact analytical solutions of the hydrodynamic equation for the boundary layer thickness are available for only a limited number of geometries. Consequently, a mass-transfer coefficient, k, is usually

Jan 1, 1967

By Bülent Erdem, Zekeriya Duran, Tuğba Doğan

The objective of this study was to evaluate the potential health risk associated with exposure of dozer operators to whole-body vibration. Measurements were made on 31 dozers used in different surface mines in Turkey. Predictions of adverse health effects of vibration were based on the standards BS 6841:1987, ISO 2631–1:1997, ISO 2631–5:2004, and the EU Vibration Directive:2002. Operators experienced high and comparable levels of vibration acceleration and dose during all dozer tasks: pushing the material (DOZE), moving forward (FORWARD), moving backward (REVERSE), and ripping (RIP). Specifically, DOZE, FORWARD, REVERSE, and RIP showed high potential of adverse health effects in terms of vibration dose according to the worst-case axis and vector sum criteria and a moderate adverse health effect for acceleration according to the worst-case axis criterion. Operators of large dozers were exposed to lower levels of vibration. However, no statistically significant relationship between vibration exposure levels and the propelling mechanism and the service time of dozers, operator experience, operator age, and ground type was found.

Jun 16, 2022

By O. G. Kiel, G. W. Swift

The concept of "a continuous succession of steady-states", which has been applied successfully by Aromfsky and Jenkins to obtain a solution for the nonlinear partial differential equation describing the transient Darcy flow of gas through porous media, is demonstrated to be equally valid for transient non-Darcy flow. A mathematical model, which numerically solves the partial differential equation, is used to check the validity of the succession of steady-states solution. Comparison of sand-face pressure histories compelted by the two methods shows excellent agreement. The utility of the succession of steady-states solution in predicting performance of gas wells rests in the fact that no special computation equipment is required. The development of the succession of steady-states solution leads also to a practical method for determining and analyzing field test data. A method for taking gas-well test data under constant-rate conditions is presented. Experimental data obtained in the field by employing the constant-rate method are presented and analyzed in accordance with the succession of steady-states solution. Analysis of data in this fashion is demonstrated to give direct "in situ" information for reservoir permeability, porosity and turbulence or non-Darcy coefficient. INTRODUCTION The economics of gas production are dependent upon the transient behavior of flow within the reservoir. For production from a finite reservoir, the transient flow behavior can be subdivided into two parts. At first, the transient caused by the movement of the pressure "wave" into the reservoir is of importance. Later in the production history, the pressure-wave movement ceases and the second transient stage of material depletion becomes controlling. For reservoirs of relatively high permeability, it can be shown that the pressure wave moves into the reservoir and stabilizes quite rapidly. In the case of relatively impermeable reservoirs, quite the opposite is true. Although it is theoretically possible to compute the production capability of a well from the properties of the reservoir as determined by static tests and core analyses, more reliable information is obtained by conducting flow tests on the well and thereby obtaining some measure of "in situ" formation properties. For gas wells, there are two basic types of tests in existence: the flow-after-flow method,' and the isochronal method.' Both of these techniques are tailored to obtain data that can be analyzed in accordance with the empirical performance equation: In addition, the isochronal method makes provision for the sluggish nature of pressure-wave movement in "tight" formations by requiring pressure build-up between flows and by stipulating that data obtained on successive flows be analyzed at equal elapsed flow times. It can be demonstrated that either test is valid for reservoirs of high permeability. Further, since it has been pointed out that the pressure wave stabilizes rapidly for reservoirs of this type, tests of relatively short duration will give stabilized information on the performance of a well. Further decline of sand-face pressure and/or production rate may be determined by employing material-balance techniques. Cullender' points out that for relatively impermeable reservoirs the flow-after-flow method gives invalid results. (See Appendix C.) If the isochronal method of testing is used, there are two alternatives: (1) the tests must be conducted for a sufficient length of time to obtain stabilized information (which may require months to accomplish); or (2) some method for extrapolating the results of short-term isochronal tests must be employed. The first alternative is impracticable because of manpower, conservation and economic considerations. Recourse to the second alternative requires some assurance regarding the reliability of the extrapolation technique. Poettmann and SchilsonJ present an empirical method for predicting stabilized performance. The present investigation was originally initiated to determine the reliability of this technique. To do this, a mathematical model was developed to simulate the Darcy and non-Darcy flow of gas through porous media. The model consisted of a finite-difference approximation of the nonlinear partial differential equation which was solved on an IBM 7090 computer. Long-term production histories were simulated by the model and compared against predictions obtained from the Poettmann-Schilson method. As the work progressed, it became apparent that a straightforward predictive equation could be developed by utilizing the concept of a succession of steady-states. As a result, the emphasis of the work was redirected to exploit the advantages of the new method.

By Walter W. Kaufman

This report summarizes a study conducted to determine the state of the art of various rock removal systems and their capabilities. The Objective of the study was to determine if currently manufactured equipment can adequately accomplish rock removal in surface mine reclamation applications. Evaluations of state reclamation regulations, with regard to topsoil rock content, were made to determine the rock removal requirements. The major categories of equipment studied are rock pickers and rock rakes. The impact of rock removal implementation on the reclamation operations is discussed in detail.

Jan 1, 1979

By M. M. Wong

The Bureau of Mines, under a cooperative research program with four lead companies, has investigated a nonsmelting process for the production of lead metal. The process, which would eliminate sulfur dioxide generation and minimize particulate lead emissions, involves ferric chloride leaching of galena concentrate to produce lead chloride, followed by molten-salt electrolysis of the lead chloride to yield lead metal and chlorine. This chlorine is used to regenerate ferric chloride in the leaching solution. The process was tested in an experimental unit with a capacity of 500 lb of lead metal per day. The tests were performed in three 10-day and six 5-day campaigns, during a period spanning 28 mo. The study was carried out using a southeastern Missouri lead concentrate. Typical lead recovery was about 98 pct. Process problems related to impurity buildup and control were studied. When copper and silver impurities were removed from the leaching solution, a lead metal purity of 99.999 pct was obtained. Lead-in-air levels and lead-in-blood levels of operating personnel were monitored. The process has potential for producing lead with minimum pollution, but is not ready for commercial utilization. Operation of a prototype commercial electrolytic cell and a full-scale pilot-plant investigation by industry are needed to evaluate the commercial viability of the process.

Jan 1, 1983

By Y. A. Chang

The objective of the present study is to evaluate and compile the relevant phase equilibria and thermodynamic data reported in the literature for the ternary system Cu-Fe-S. It is hoped that the results presented here will be useful to practising engineers and scientists in industry who are attempting to improve continually the existing processes of copper extraction and refining. At the same time, the present work will undoubtedly reveal the lack of some basic data which are important for the improvement of our existing extractive processes. Lastly, this work will also show that the development of theoretical models for the alloy phases in the Cu-Fe-S system is essential before complete consistency between the phase equilibria and the thermodynamic data can be achieved.

Jan 1, 1976