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By Toshihiko Emi

The quest for cleaner steel is driven by increasingly stringent requirements from the manufacturing and construction industries. Key issues are the occurrence and removal of inclusions; These are discussed in the context of the unit processes of deoxidation, refining, transfer and casting of molten steel. Process thermodynamics and kinetics are also discussed. Recent progresses achieved and problems yet to be solved are elaborated, and an integration of the unit processes into a system to produce extra clean, steels with better performance is presented.

Jan 1, 1999

By Wayne W. Murdy

Since 1993, Newmont has been actively growing through the development of three major foreign mining operations with a fourth under construction. The first project, Yanacocha in Peru began operating in October 1993 at a time when political and business risk in that country was considered high. In 1995, Newmont began operating the Muruntau Joint Venture in Uzbekistan, the first of its kind in the CIS. In early 1996, Newmont started operating the Minahasa mine in Indonesia. Now, in early 1997, Newmont is undertaking the construction of a $1.9 billion project in Indonesia and is completing a feasibility study with our partner for the development of a gold operation in Mexico. All of these projects have been considered "risky" by most standards, and Newmont has been very successful in all of them through risk mitigation programs including utilizing strong and successful in-country partners, concentrating on developing a strong national workforce with minimal expatriate employees, utilizing World Bank, EBRD and IFC financing and building and maintaining strong ties with host governments. This paper describes in more detail, some of the risk mitigation programs that Newmont has used to successfully grow the company through development of major foreign mining operations.

Jan 1, 1997

By A. R. Khodabandeh, T. Nematkhah

Correct selection of forging parameters is very important to produce sound superalloy parts. In this investigation nickel-iron base superalloy IN901 successfully forged and seal spacer, which is a part of airplane with about 11 kg weight has been produced. Forging has been performed on the basis of hot compression results, which show deformation above 1100°C associated with dynamic recrystallization (DRX) which can increase the workability of material. On the other hand annealing at 1100°C decreases the flow stress during hot compression, and then increases the material formability. Then billets annealed at 1100°C in electrical furnace for 24 hours and reheated again to 1100°C before forging. Initial square cross section billet with 128mm side and 202mm length forged immediately after reheating by 80MN mechanical press. Specimens forged in five steps: upsetting, three steps molding and finishing. Preformed and molded specimens reheated in electrical furnace before later step of forming. Finally specimens trimmed by 1 OMn mechanical press and hot set by hydraulic press and then cooled in air to room temperature. Results show that reheating temperatures has been selected correctly because there isn't any surface crack and die cavities filled completely by forging material. Material flow has been carried out properly and there isn't any defect in critical points especially in extradoses and intradoses. Microstructural examinations show that grain boundaries contain Ti-rich globular particles that formed during cooling.

Jan 1, 2006

By A. F. Baker

Tests were conducted in commercial foundries to determine the suitability of calcined anthracite as a cupola fuel. The calcined anthracite performed satisfactorily at two of the three foundries where iron-melting tests were conducted. Performance at the third installation was unsatisfactory because metal temperatures deviated widely and, in general, were lower than is desirable for the type of castings being made.

Jan 1, 1963

By L. Veleva, Garcia. A., G. Perez

Aluminum is a metal used for the transmission of electricity of high voltage, in the construction industry and other areas. In atmospheric conditions aluminum forms an oxide layer (Alz03'H20) as a result of its corrosion, entering the passive state. The oxide layer can be destroyed by the presence of ions (Cr, SOx-n) developing localized (non uniform) corrosion attack by pitting, difficult for evaluation. The concepts of fractals and self-similarity were used in this study for the characterization of the development of localized corrosion. Images obtained with a scanning electron microscope (SEM) of samples of electrolytic aluminum wire that have been exposed during one year in ruralurban and marine-coastal environments of the humid tropical climate of Mexico, have been processed. The development of pitting has been studied as a function of time, making a statistics of the frequency of appearance of pits versus the area occupied by them. The data show that the distribution of the pits follows a power law. Therefore, the concept of self-similarity can be applied for the study of the phenomenon of localized corrosion, describing their development with time.

Jan 1, 2006

By Larry A. Lass

The U.S. Bureau of Mines, in cooperation with the Iron Range Resources and Rehabilitation Board, investigated the potential of using northeastern Minnesota papermill waste sludges as a binder for Mesabi Range iron ore (taconite) concentrate. Sludges from five different commercial papermill waste treatment operations were evaluated in laboratory tests. Except for the coarsest sludge, all were fairly easy to blend with the taconite concentrate using conventional mixing methods. The coarsest sludge had to be reslurried at 2 pct solids before adding it to the concentrate in order to obtain pellets without visible sludge clumps. Drying and grinding the sludges made them less effective as binders because of a lower degree of rehydration. On a dry weight equivalent basis, twice as much raw sludge binder was required to obtain similar pellet physical properties as with bentonite; however, the pellets made with raw sludge had superior metallurgical properties. Over 30 pct higher reduction rates and over 1500 C higher softening temperatures were obtained with sludge binder than with bentonite. Sludge D, which had the lowest fiber and the highest alkali metal content, resulted in the lowest reducibility enhancement. Even though more raw sludge was required than bentonite, the sludges have virtually no value, and therefore may provide a cost-effective additive binder for producing improved metallurgical-quality pellets. Large-scale testing has not been done to confirm these laboratory results.

Jan 1, 1989

By Liz Diaz, Tacio Ferreira

Capstone Copper’s Pinto Valley Mine faced challenges in recovering rock and ore on final walls because of geotechnical constraints that require restrictions on methods for loading blastholes adjacent to the pit boundaries to preserve wall stability. The operation had been using the same drill and blast designs for years. With changing geology, such as harder rock, as mining progressed, material was being left unmined in final walls because of poor breakage. The amount of unrecovered, unprocessed ore was estimated at approximately 380,000 tons a year generated from an average of 60 final wall blasts performed annually. The engineering team from Capstone and Dyno Nobel engaged to minimize the amount of material left on the final pit walls. This paper presents how we collected data, reviewed design standards, and found opportunities to improve ore recovery from pit final walls without increasing drilling and blasting costs. The results collected from implementing the new design on two benches showed the potential for extra revenue of approximately $3.6 million generated annually from reducing final wall unrecoverable underbreak by nearly 71% on the mine’s highwalls.

Feb 1, 2025

By Nan Hua

As a high production and high efficient mining method, top coal caving method is now widely used in China. However, as more extra-thick coal seams are mined, it becomes more and more difficult to make the top coal fully broken up, resulting in more and more top coals flowing into the gob, rather than onto the rear AFC at the working face as designed. This research is aimed to investigate the failure mechanisms of the extra-thick top coal caving mining method.

Jan 1, 2009

By J. Herbst, J. Groppo, A. Noble, R. Q. Honaker

"Coal and coal byproducts produced annually contain a sufficient amount of rare earth elements (REEs) to meet current U.S. demand. The REEs exist in the form of minerals, ion-adsorbed elements associated with clays, and chemically bonded elements within the organic coal matrix or host mineral. Researchers at three universities collaborated to evaluate the effectiveness of existing physical and chemical concentration processes for the recovery of the REEs. The efforts found that physical separation processes can increase the total REE content in the thickener underflow material collected from a Central Appalachian coal cleaning facility from around 300 ppm to values greater than 17,500 ppm on an ash basis. Leaching followed by solvent extraction was found to be the most effective to recover the REEs from coarse middlings materials collected from multiple coal basins, as indicated by recovery values exceeding 80 percent. Based on material characterization data and process evaluations conducted for several potential feed coal sources, economic recovery of the REEs will require byproduct production of both clean coal and REE concentrate using a process flowsheet that is unique for each source. IntroductionRecent studies initiated by the National Energy Technology Laboratory showed that U.S. coals contain significant amounts of rare earth elements (REEs), suggesting that rare earth minerals (REMs) and/or REEs can be produced as byproducts (Ekmann, 2012). According to the report, the richest source of REEs is the Central Appalachian coal. At present, there are 208 coal preparation plants located in the region consisting of areas within the states of West Virginia, Kentucky, Pennsylvania, Virginia, Alabama and Tennessee, with a total capacity of 166,495 t/h, or more than 1 Gt/y (Fiscor, 2014). If only a portion of these plants are retrofitted with advanced separation processes, the U.S. coal industry would become a significant producer of REE concentrates as byproducts. An inherent advantage of becoming a byproduct producer of REEs is that no mining cost needs to be part of the production cost."

Jan 1, 2017

By Reinhard Gertl, Maximilian Weithaler, Harald Kammerer, Juan Pablo Muñoz, Juan-Carlos Rueda

The Guillermo Gaviria Echeverri tunnel and its access roads project in Antioquia, Colombia is a mega infrastructure project that includes a road network with the longest tunnel in Latin America and several short tunnels, the latter being the focus of this study. The design of the project required careful consideration of several special factors, such as the tunnels’ steep slopes of up to 5%, high fire load of 100 MW, bidirectional operation, and short lengths that make it difficult to place ventilation equipment. The combination of all these parameters cause a challenging design problem for the ventilation systems and smoke control of the short tunnels. To address this challenge, a risk assessment study was conducted to support the design of a new and innovative ventilation strategy that deviates from relevant guidelines and standards, like the Austrian RVS [1][5][6] or the German EABT [8] in order to provide a customized solution for this particular project. This strategy resulted a cost-effective solution, that allowed a reduction in the number of required jet fans and at the same time reaches or reduces the risk level compared to traditional ventilation strategies.

Jun 13, 2023

By José Salas, Vicente Salas, Fredy Butrón

El objetivo principal, de la presente investigación aplicada, es determinar cuantitativamente, la viabilidad tecnológica, del aprovechamiento de la energía eólica, minihidráulica, y combinadas de los ríos de las cuencas bajas de las cordilleras, y su sostenibilidad económica; tomando como ejemplo característico, la cuenca baja del rio Ocoña en Arequipa, Perú. Como objetivos parciales, se estudia de forma individual, el tema eólico, minihidráulico

Sep 29, 2023

By R Hartner

Digital optical microscopy (DOM) and automated SEM-based (ASEM) mineralogy systems (MLA, QEMSCAN) have experienced significant developments within the last decade. However these developments have been independent from each other and the two mineralogical techniques have so far not yet been integrated to combine the strengths and technical benefits of both analytical platforms. This detailed comprehensive mineralogical information is critical support for geometallurgy.Major hardware and software advances in DOM in the last few years have provided important new capabilities with potential applications to automated mineralogy. These technological advances have been largely driven by sectors outside mining (eg medical pathology) and have not yet been widely adopted within the minerals industry. The advent of DOM offers significantly more automated mineralogy capabilities than traditional expert-mineralogist driven optical microscopy. This is based on advances in automated image acquisition, high resolution cameras for digital imaging, imaging of large areas through mosaic options, integration of multiple layers and application of advanced image analysis techniques.Ongoing research involves combining the outputs of DOM and ASEM-based microscopy to create new capabilities for integrated microscopy based on development of advanced cross-platform image fusion and data integration between DOM and ASEM (exploiting the benefits of both analytical platforms). This requires non-linear image registration and transfer of mineralogical identification from ASEM to DOM systems using sophisticated image manipulation and data analysis software.Examples will be given of image fusion and data registration for a range of different ore types. Image fusion techniques are demonstrated using a porphyry copper deposit sample where sulfides and precious metals are classified using the MLA and gangue mineralogy obtained from DOM images. Data integration enables creation of a library containing optical property variability information for minerals identified by the MLA; thus reducing the reliance on skilled mineral identification by supplementing human interpretation

Sep 5, 2011

By Chas. B. Dudley

A Discussion of the papers of Mr. James Gayley, on "The Application of the Dry-Air Blast to the Manufacture of Iron," and of Mr. J. E. Johnson, Jr., on "The Physical Action of the Blast-Furnace," by Messrs. Charles B. Dudley, R. W. Raymond, J. E. Johnson, Jr., William F. Mattes, James Gayley, David Baker, John Birkinbine and F. E. Bachman. (Washington Meeting, May, 1905.) CHAS. B. DUDLEY, Altoona, Pa.:-Pam not a blast-furnace man, and this always puts me it a disadvantage because I cannot go into the details of the making of iron and steel. I have not the experience, and have to take the statements of other people, so what I say regarding the subject of this paper is not in the sense of an expert. When I first heard of Mr. Gayley's experiments, I said to myself, " I fear they will result in failure, since, apparently, Mr. Gayley has forgotten one chemical fact, namely, that carbon does not combine with oxygen in the absence of water-vapor." This fact which was so astonishing when it was first brought out some years ago, and which those who are interested may find in the Journal of the Chemical Society of London, for 18S5, page 349, and 1894, page 611, led me to think that the drying of the air would be a mistake. The general subject of the influence of water-vapor on chemical action is a large one; but the special point in which we are for the moment interested, namely, the influence of water-vapor on the combustion of carbon, was especially treated by Mr. H. B. Baker, in the papers referred to. Apparently, however, as the result of Mr. Gayley's experiments, we are to learn that the amount of moisture still left in the desiccated air is sufficient to secure perfectly satis¬factory combustion. In thinking over Mr. Gayley's paper, it occurred to me that there were two alternatives, either of which might be chosen, namely, we might dry the air as Mr. Gayley does, or possibly we might, in a very much simpler way, simply saturate the air at a constant temperature, and thus get uniform working and

Sep 1, 1905

By MAHESH SHRIWAS, CHRISTOPHER PRITCHARD

Ventilation monitoring and control in mines are becoming an integral part of day-to-day activity for maintaining the health and safety of miners. This paper evaluates potential real-time monitoring solutions for detecting and reducing diesel particulate matter (DPM), mine fires and dust in situ and examines the state-of-the-art use of ventilation monitoring and control in underground mines for detecting and reducing air contaminants to acceptable regulatory limits. In this study, relevant documents, including research papers, trade publications and manufacturer website information, are reviewed to identify research gaps. This paper also includes evaluations of contemporary sensors (airflow, gas, dust and silica), control system and software technologies, data transport systems, the Industrial Internet of Things (IIoT), ventilation network simulators and control devices to identify potential health and safety research gaps. Examples of some mines in Canada, Australia and the United States that have been using ventilation monitoring and controls are included as well. Overall, this review identifies multiple challenges and research gaps in applying mine monitoring and control systems that could be the focus of future research, offering potential improvements to miner safety and health and financial benefits.

By Robert H. Dickson

This paper describing the mining practices at the Verde Central mine at Jerome, Ariz., is one of a series being prepared by the United States Bureau of Mines on mining practices, methods and costs in various mining districts of the United States. ACKNOWLEDMENTS The costs contained in this paper were prepared by R. J, Huddleston, chief clerk, Verde Central Mines, Inc.

Jan 1, 1931

By Raymond M. Stateham

Calculations based on data obtained from measurements of smoke from coal-fired powerplants predict that infrared imagers will be useful tools for smoke vision. Infrared imagers operating in the 3-to 5-um spectral region have been evaluated for this purpose. A mine opening 110 meters long was filled with smoke from burning coal, and two men, wearing breathing apparatuses, moved through the smoke to serve as targets. The men were detected and identified at 80 meters.

Jan 1, 1976

By M. M. Tilman

The objectives of this research were to determine the practicability of using cobalt as a means of controlling the amount of ferrite in the micro-structures of semiaustenitic stainless steels, and to determine the effects of reduced ferrite content on mechanical properties of these steels. Cobalt additions of up to 3 weight-percent were made to type 17-7 PH2 (AISI 631) stainless steel. Ferrite contents were determined for alloys in the aged condition, and for alloys quenched from the hot working temperature. Ferrite can be completely eliminated from the microstructure of 17-7 PH stainless steel by additions of cobalt, but complete elimination of the ferrite phase results in lower tensile strength, yield strength, and hardness. Tensile properties, hardness, and impact strength were determined for aged material. A subzero temperature treatment before heattreating was necessary to obtain maximum strength in the alloys containing cobalt. Addition of 2 weight-percent cobalt enhances mechanical properties of 17-7 PH stainless steel.

Jan 1, 1968

By Flavio Rojos-Tapia, Samuel Sánchez-Pino, Marcelo Fernández-García, Samuel Sánchez-Baquedano, Rainer M. Imhof

"Pneumatic flotation was introduced to the Chilean copper mining industry in 1993 by Ingeniería de Minerales S.A., being implementation in 1994/95. The technology is based on the designs and development of Dr. Rainer Imhof from Germany and from Chilean copper processing experience.Pneumatic flotation has been successfully used for sulphide and oxide copper minerals and copper slag, iron ores (reverse flotation), gold and promising results with molybdenum as product. Extremely hard conditions were applied in flotation process such as roughing, cleaning, scavenging. Pneumatic flotation can be applied for any type of mineral which has to be separated by flotation. Even very dense and heavy slurries can be processed, the range of the particle sizes to be collected is very wide, and the number of cleaning stages needed normally is one in our experience until now.The good performance of the technique can be explained by the high gas hold-up and the very effective micro-turbulences which boosts the attachment to the bubbles changing dramatically the flotation time concept. Some economic high lights are: less energy consumption, less maintenance costs, simple and reliable to operate and it is required a small area to install the circuits.As a result of the Chilean mining industry experience, it can be concluded that the pneumatic flotation can be regarded as an excellent alternative to the conventional way of Mineral Processing.INTRODUCTIONDerived from seventies, works in Germany about pneumatic flotation with Prof. Simonis (Technical University of Berlin) and Prof. Bahr (Technical University of Clausthal), it has been developed an interesting flotation technology in Mineral Processing, with the designs developed by Dr. Rainer Imhof, who has been known for more than ten years (Imhof, 1998) by his contribution at Ekof, KHD, Allmineral and the actual company Maelgwyn Mineral Services where he is a Technical Director. Ingeniería de Minerales S.A. has been working ten years deeply involved with the technology developed by Dr. Imhof and is more than ten years experienced with pneumatic flotation, from Wits University and Mintek in South Africa (Sánchez, 1990), (Sánchez, 1990)."

Jan 1, 2003

By R Saha, D Barry, C Mawdesley, O Bertoli

Kriged estimates are not typically calculated on blocks substantially smaller than the sample spacing (eg the Standard Mining Unit or SMU). Moreover, the sample spacing for quality variables is often much greater than the SMU size. For short to medium term planning decisions, the shorter term variability in the quality variables is a key economic consideration in defining, setting and meeting coal product specifications.Global uncertainties can be calculated using Drill Hole Spacing Analyses (DHSA). However, knowing the precision of a variable for a one or two year production volume is usually not adequate for variables with low spatial continuity that may fluctuate significantly over daily, weekly, SMU, or shipment volumes.Is there a feasible, reasonable and valid geostatistical method to model the uncertainty of coal quality variables on blocks substantially smaller than the drill spacing (say on the SMU)?The validity of using co-kriging variances, calculated on SMUs to characterise local uncertainty, was tested using a suite of conditional simulations generated for several quality variables for BHP’s Blackwater operation. The conditional simulation results were used as a benchmark against which the results derived from the kriging variances could be compared.The agreement between the kriging and simulation methods for thickness is excellent, with much closer correlations than for the quality variables. Typically, the kriging variances give very reasonable approximations to the simulation-based uncertainties, although there could be some systematic discrepancies which may become much more critical if a classification is to be based on a thresholding of the SMUs relative uncertainties.CITATION:Mawdesley, C, Barry, D, Bertoli, O and Saha, R, 2017. Local uncertainty benchmarking – a coal case study, in Proceedings Tenth International Mining Geology Conference 2017, pp 43–50 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

By F. v. d. Meer, G. Kretschmar, T. Mütze, T. Leißner

"Dynamic air classifiers separate particles in a gas flow due to different particle trajectories utilizing differences in the settling velocity of particles as characteristic property for separation. The present contribution takes a close look at the separation of heterogeneous mixtures, in which valuables and gangue minerals show significant differences in density. The focus was on a moist iron ore sample, which was characterized in terms of mineralogy, grain size distribution, and particle size distribution. The material was classified at a cut size of 45 µm and at feed moistures between 0 and 6 wt.-%. Additionally to standard characterization techniques, the moisture of both products was measured as well as the yield of fines as product fraction in a corresponding processing plant. In addition, an automated mineral liberation analysis (MLA) provided information of the enrichment and segregation of individual mineral phases in the products. The MLA of the classification products reveals a selective comminution of the mineral phases and especially on overmilling of the valuables. For the first time, the separation of individual mineral phases has been assessed and compared to the classic assessment of classification processes by means of particle size analyses. KEYWORDS Dynamic classifier, segregation, MLA, selective comminution INTRODUCTION Dynamic air classifiers separate particles in a gas flow due to the different trajectories of the particles. The result of such a separation process depends on the gas throughput of the classifier, the dimensions, design and rotational speed of the deflector wheel, as well as the state of dispersion and thus the geometry of as well as the turbulence and interparticle interactions in the separation zone. Air classification of moist feed materials can be divided into several sub-process (Leschonski, 1977; Mütze et al., 2016): - dosage of the feed material, - dispersing the solid feed material into a gas stream, - feeding the dispersed material into the classification zone by pneumatic conveying, - drying of moist particles during pneumatic conveying, - separation of coarse and fine particles, and - separation of fine particles from gas."

Jan 1, 2018