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By Enrique Monge

El presente texto señala las plantas de tratamiento mecánico de acero, así como las plantas de rodamiento para barras y planchas semiterminadas, las de rodamiento para la producción de barras comerciales, la producción de formas estructurales en la industría del acero en los Estados Unidos de Norteamérica.

Jan 1, 1958

By Liu Xinghua

Yuanjiacun iron ore located in Shanxi province of China has finely disseminated grain size and contains refractory iron-bearing silicate gangue minerals such as chlorite. Therefore, a large amount of secondary slime (the content of -10µm fraction was up to 32.92%) was produced inevitably in fine grinding process, and chlorite was also enriched in concentrate from the content of 4.3% to 14.8% after high intensity magnetic separation. These two characteristics result in the difficulty to deal with Yuanjiacun iron ore by flotation. In this test work, contrast tests between single reverse flotation and selective flocculation desliming-reverse flotation were conducted on Yuanjiacun iron ore. The test results show that after selective flocculation desliming, the iron grade of cationic reverse flotation concentrate increases by 6.15% and the recovery increases by 7.25%; the iron grade of anionic reverse flotation concentrate also increases by 2.15%. Furthermore, analyses of grain size composition and mineral composition were carried out on separation products, the results indicate that selective flocculation desliming plays a dual role of optimizing grain size composition of flotation feed and removing iron-bearing silicate gangue minerals (chlorite) effectively.

Sep 1, 2012

By M. P. Youker

USE OF LOW-PRESSURE GAS BURNERS IN OIL- FIELD BOILERS

Feb 1, 1922

By S C. Barrie

St BarbaraÆs Marvel Loch operations have successfully used longhole open stoping as the primary mining method for a number of years. A transition to Core and Shell mining was implemented in 2009 to recover substantial ore grade resources remaining in sill and rib pillars. The transition to core and shell for the Exhibition lode required continuous waste filling of created voids and thus the removal of the crown pillar at the base of the Exhibition pit by blasting. Access to the top of pillar was denied as the pit was partially rock filled with waste rock from underground development.Beyond the technical challenges of the blasting project, a simple and transparent risk management process was developed to ensure appropriate controls and mitigating strategies were in place to minimise risk to personnel during the pillar removal process.Although failure of the crown pillar was anticipated but with the actual timing unknown, on 25 December 2011 the crown pillar yielded during normal mine operations. Engineered and isolation controls in place at the time were of a sufficiently high standard to ensure limited exposure of the underground workforce and minimal damage to mine infrastructure. Successful risk management through implementation of appropriate controls during the project lifecycle of two years and three months proved to be fundamental to the safe removal of the crown pillar.CITATION:Barrie, S C, 2012. Successful risk management through project life cycle for removal of the crown pillar at the Marvel Loch Underground Mine, in Proceedings International Mine Management 2012, pp 125-134 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 20, 2012

By Agne Rustan

The goal of this paper is to describe Fragblast 10 for those who did not have the opportunity to attend the Symposium and also give some examples of new research findings used in practise in some countries throughout the world. Also some entertainment events from the symposium are described.

Jan 1, 2013

Pictured on these pages are the six RMCMI Scholarship Award Winners for the 1988-89 year followed by a brief profile. All winners were present as guests of the Institute at the June convention in Durango, Colorado to receive recognition at the Welcome Session Monday, June 26, 1989. Each state vice president served as the host for the collegiate winner. In addition to receiving a plaque from the Scholarship Chairman, Keith McGinnis, each winner receives $500.00 tuition credit for the coming academic year. As this is a continuing award, the winners from the previous year will receive another $500.00 for tuition credit in their senior year if they have maintained good academic standing and have been recommended by their university. Criteria for these awards to be made in the spring annually is (1) That the award be made to a sophomore student and used as tuition during the junior year. (2) That the recipient be both a U.S. citizen and a resident of the state involved. (3) That the recipient have good academic standing, be pursuing a degree in a mining related field and have an expressed interest in Western coal as a possible career path. The scholarship program includes curricula other than those in the mining departments, but in the engineering disciplines, such as geology, mineral processing and metallurgy. Contributions to this worthy project are tax deductible to each individual RMCMI member or his firm. Through annual donations of $100.00 or more, the Patrons of the Institute fund the scholarship program and the various vice presidents contribute the travel expenses to convention for these outstanding young collegiates. Donations to this worthwhile program may be made payable to RMCMI Scholarship and mailed to the RMCMI Office, 2700 Youngfield Street, Suite 100, Lakewood, CO 80215. Profiles of the 1989 Scholarship Winners follow. [ ] David P. Pelletier University of Arizona Tucson, Arizona David is a Mining Engineering major and graduated from Santa Fe High School in 1981. He served in the Sixth Marine Regiment, Second Marine Division of the United States Marine Corps from December 1982 thru December 1985. He is a student member of SME-AIME and has held the offices of treasurer, vice president and president. He works volunteer shifts at the University of Arizona San Xavier Mining Laboratory [ ] Johnny F. Blizzard Colorado School of Mines Golden, Colorado A high school graduate of Longmont, Colorado, Johnny carries a 3.968/4.000 at Mines, majoring in Mining Engineering with a minor in Metallurgy. His name has appeared on the Academic Dean's list for the past two years. He received the Robert M. & George R. Harris Scholarship during this past year. He is a student member of SME-AIMMP and an executive council member of CSM's chapter of AIME. Summertimes, Johnny works as a miner for Edger Mine in Idaho Springs, CO on an experimental project for USBM.

Jan 1, 1989

By Hugo Toledo, Karin Batallanos, Antonio Bravo, Rafael Carpio

Este documento técnico ha sido desarrollado a partir de una perspectiva empresarial orientada hacia la optimización de los recursos y activos con el objetivo de aumentar la rentabilidad del negocio. Para lograr este propósito, fue crucial la apertura y sinergia y entre las áreas de Mina, Planta y Mantenimiento, ya que su interacción conjunta desempeña un papel crucial en la consecución de nuestros objetivos.

Sep 29, 2023

By P Wahyono, H Vega, S Riza, P Vergara, P Gonzalez-Carbonell

PT Freeport Indonesia (PTFI), operating in the Ertsberg Mining District in the Province of Papua, is developing the Grasberg Block Cave copper-gold mine. The site aims to output 160 000 t/d and will be located underneath the current Grasberg Open Pit. Initial studies of the potential to develop a block cave mine in the Grasberg orebody have revealed that the mine will require significant volumes of air. The Grasberg Block Cave (GBC) project requires four primary fans (3750 kW each) to support production at full capacity.Fan #1 commissioning was accomplished successfully on 9 February 2012. However, Fan #2 chamber, which is separated by a 20 m pillar, had not been completed. The main challenge was Fan #2 chamber still needed to be benched. The risk of damage to the critical infrastructure in Fan #1 chamber, including ground support, cracks in pedestals, and misalignment in the impeller shaft were considered. The challenges were blasting the bench without damaging the surrounding infrastructure, completing the work safely and meeting the schedule. This was achieved with the engineering control methodology. This paper summarises the benching process of Fan #2 chamber and its impact upon Fan #1.CITATION:Vega, H, Riza, S, Gonzalez-Carbonell, P, Wahyono, P and Vergara, P, 2013. Excavating an underground primary fan chamber that is adjacent to a fully operational primary fan in PT Freeport Indonesia's Grasberg Block Cave Mine, in Proceedings The Australian Mine Ventilation Conference , pp 115-122 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By T. Bajpayee, J. Ellenberger

Microseismic monitoring and evaluation is one aspect of the National Institute for Occupational Safety and Health (NIOSH) research program. Roof falls are often preceded by a period of elevated microseismic activity, but not all periods of elevated activity result in a roof fall, nor do all roof falls occur after some amount of elevated activity. The objective of this study is to review periods of elevated microseismic activity and determine whether fracture activity rate can be used to anticipate the initiation of roof falls. The study was carried out at an underground limestone mine where major roof falls are associated with excessive horizontal stress. The progression of roof falls was detected by the microseismic signature produced by the rock falling from the mine roof onto the mine floor, which is termed a roof fall impact event. A total of nine elevated fracture activity periods that resulted in seven major roof falls were examined. It was observed that elevated fracture activity preceded the initial roof fall impact event in three out of four major roof falls. The initial impact event was not identified for the remaining three roof falls. Fracture event rates were analyzed and a roof fall alarm trigger of five fracture events in a ten minute time period was established for this test case. The fall alarm trigger was tested against six of the elevated activity periods. Four roof falls occurred in the six periods of elevated activity, and two would have triggered the alarm before the roof fall occurred, while two false alarms were generated. The results show that limited success would have been achieved by the microseismic system as a roof fall alarm trigger. However, the trigger would have been successful at warning of the onset of elevated activity, allowing mine employees to respond appropriately. The study highlighted some issues with implementing such a system in an operating mine, including the need for real time identification of fracture related microseismic signals among mining induced signals, and accurate location and identification of fracture clustering.

By A. M. Hefny, F. P. Siew, P. G. Ranjith

Fracture initiation and propagation, being one of the most intensive subjects in rock mechanics; contribute significantly to the deformation of jointed rock masses. An experimental study on fractured granitic rock was carried out to determine the peak strength of specimen under triaxial loading conditions. The commonly observed failure mode for rock specimens in this study was found to be the shearing of the plane of weakness. The minimum peak strength of fractured rock is observed when the joint orientation is approximately 70° to the horizontal axis. Based on experimental test data, an empirical expression was developed to accommodate the effect of joint orientation and joint trace length in estimating the peak strength of fractured rocks. The predicted values of peak strength using the proposed equation well agree with the experimental results carried out on singly fractured specimens under triaxial loading conditions. The threshold stress values of crack initiation and propagation depend on joint geometrical parameters, their degree of interconnectivity, as well as surrounding stresses on the fracture plane.

Jan 1, 2003

By Carl Fisher

A microseismic roof fall warning system was field tested in Western and Eastern coal mines in the United States to better define the capabilities and limitations of the microseismic method in predicting roof fall. Microseismic event and energy type data were obtained and documented for twenty-three coal mine roof falls, Field test results indicate that both the microseismic event and energy methods, as applied in this development effort, have a high probability for successful application in a commercially practical roof fall warning system. Based on the results and experience obtained during field testing, a commercial prototype microseismic roof fall warning system was designed and constructed. Although it was the intent of the program to field test the commercial prototype system, delays in equipment fabrication and contract time limitations did not permit field testing.

Jan 1, 1980

By H Y. Niu

The coal left in the goaf is easily submerged by groundwater damage. During the mining process of the underlying coal seam, it is necessary to drain the water in the overlying goaf. The coal sample is prone to spontaneous combustion after being soaked in water and air-dried. To explore the effect of micro-functional group transformation of water-immersed coal samples on the spontaneous combustion characteristics of coal samples during the low-temperature oxidation process. Using the experimental method of infrared spectroscopy, the migration law of special functional groups under different oxygen concentrations of water-soaked coal samples was analysed. By means of thermal analysis, the endothermic and exothermic properties of the functional groups in the water-soaked coal samples were studied. The results show that: the higher the oxygen concentration, the more oxygen-containing functional groups in the water-soaked coal sample, compared with the 18 per cent oxygen concentration, the 14 per cent oxygen concentration has a small increase, and the chain length is shortened. The temperature increase together with the oxygen concentration content determines the functional group content, the pyrolysis process produces some functional groups. The lower the oxygen concentration, endothermic rate decreases and endothermic temperature increases, the higher the ignition temperature of coal oxy-combustion, the lower the total heat release, the higher the burnout temperature, and the faster the oxygen-absorbing weight gain and the conversion of functional groups. Below 14 per cent oxygen concentration, the oxidative combustion process will be greatly reduced. The results provide a theoretical basis for preventing long-term water-soaked coal body oxidative spontaneous combustion in shallow buried coal seams.

Oct 12, 2022

By K. Chomyn, R. Veenstra, P. Zangeneh, Hatch Ltd., C. Van der Woude, H. Ghorbani

"The furnace is the heart of smelting operations, and therefore the performance, reliability, and campaign life of the furnace are critical considerations. Furnace refractory is exposed to high temperatures and other harsh operating conditions causing brick erosion, crushing, and cracking, typically limiting the furnace campaign life and requiring costly furnace shut-downs for refractory re-lining. Despite extensive study, the in-service thermal / mechanical stresses in these complex refractory systems are not generally well understood. Hatch has developed a thermal-mechanical finite element analysis (FEA) based furnace refractory modeling approach that allows for the quantification of refractory movements, load distribution, and thermal / mechanical stresses.Due to the complexity of the refractory system, a range of models are used to identify and assess damage mechanisms and design improvements, including: 2D models, to capture expansion and movement of individual bricks, changes to load paths, and thermal stresses; and 3D models, to include the effect of differential expansion between bricks in each course, and assess overall load distributions. The 2D and 3D analyses include the effect of nonlinear temperature-dependent properties, thermal expansion, movement of individual bricks with frictional contacts (i.e., gaps can open, bricks can slide), and brick tensile or compressive failure. Both as-built and damaged conditions can be investigated (e.g., after bath zone brick erosion), for circular and rectangular furnaces. 3D models also include papering and brick joint & interface action.Analyses using these models have shown the importance of thermal stresses, papering, and geometry / arrangement of individual bricks. Results have been used to identify and assess damage mechanisms, showing good alignment with furnace autopsy observations. By using this FEA-based approach to quantify the refractory design, the risk of damage can be significantly reduced, low-cost design changes can be identified, and the furnace campaign life can be extended.INTRODUCTIONThe furnace is the heart of smelting operations and therefore the performance, reliability, and campaign life of the furnace are critical to the success of the smelting operation. Furnaces are inherently exposed to high temperatures, often in excess of 1600°C (Holappa, 2004), and furnace operating power has progressively increased over time (Voermann, Gerritsen, Candy, Stober, & Matyas, 2004). The refractory system must withstand high temperature, high heat flux, and other harsh operating conditions. These conditions are particularly significant for the furnace hearth, and can lead to damage including brick erosion due to molten material flows, crushing due to thermal expansion loads, and cracking due to severe thermal gradients within the bricks. Refractory damage typically limits the furnace campaign life, requiring costly furnace shut-downs for refractory re-lining (repair or replacement). In some cases the refractory may lose integrity causing damage to nearby equipment and harm to personnel."

Jan 1, 2016

By John L. Morning

Although faced with a slowdown in the world economy, continued inflation, and rising costs, the mining industry exceeded its 1974 raw mineral production value of $55.1 billion by 13%. The increase was due to value increases in the production of fuels and nonmetals; metals reported a decrease in value. Of 23 metals produced, 14 showed value increases; of 44 non-metals produced, 26 reported value in-creases. Because of increasing costs and depletion of high-grade reserves, the mining industry continued to rely on new technologies to maintain its profit margins. In the surface mining sector, the development of new tools and equipment played a large part in increasing production and maintaining this goal. Some of the types of equipment developed were instrumentation for control of pit slope stability, shovel power transmissions, electric wheel trucks, and single-flight conveyor systems.

Jan 1, 1977

By P. van Meurs

This paper describes a technique which permits visual observation of oil displacement processes througlrout the interior of a porous structure as thick as 2 in. A model having glass walls is filled with finely powdered glass. Such a model becomes completely transparent if the powdered glass pack is saturated with an oil having the same refractive index as the glass. When water or gar, with a refractive index different from that of the oil (glass) is injected, the model becomes opaque in the space occupied by the water (gar). visual observation and photography of these displacement processes are thus rendered possible. The following processes have been studied: (I) displacement of oil by water (linear drive) in a homo-geneous formation and in a stratified formation, (2) water flooding (five-spot well pattern), (3) solution gas-drive process, and (4) oil-bank formation. INTRODUCTION Most of the scaled model experiments heretofore carried out in the Koninklijke/Shell Laboratorium, Amsterdam, have been done in steel containers, in which oil-saturated sand packs represented the oil-bearing formation. In such experiments, for instance those on the displacement of oil by water, the cumulative oil production was measured as a function of the cumulative water injection. In order to interpret the measured production data, a need has for some time been felt for a means of observing visually what happens in the course of such experiments. Some information of this kind was obtained earlier by observing the water-oil distribution in various cross sections of the sand after the conclusion of the experiment.' However, the technique used did not guarantee that the fluid distribution remained undisturbed. Moreover, the procedure was somewhat elaborate and the information obtained limited. Therefore a new technique has been developed, which is described below. DESCRIPTION OF EXPERIMENTAL TECHNIQUE AND APPARATUS Glass models simulating part of an oil reservoir are filled with ground Pyrex glass of a specific grain size, representing the porous structure of the prototype. Before an experiment is started, the porous formation has to be saturated completely with an oil having exactly the same refractive index as the Pyrex glass powder. All light-scattering surfaces of the glass grains become invisible and the formation is then transparent. If the oil is displaced by another fluid (e.g. by water in a water-drive experiment, or by gas liberated from the oil in a solution gas-drive experiment) the formation becomes opaque in the region where the oil is expelled from the rock.* The back of the apparatus is painted black and illumination is from the front; therefore, in the photographs of the experiments, the oil-bearing formation appears black, whereas the water- or gas-invaded areas are white.

Jan 1, 1958

By John T. Eash

During the course of the war the supply of tin in this country has steadily decreased and a continued effort has been made since the beginning of the emergency to use alloys that are either tin free or contain appreciably lower quantities of it. Even with the use of emergency materials, the tin supply has become particularly acute, and it is estimated that after recovery of the far eastern mines probably one to two years will be required before our normal annual supply is attained. One of the major tin-consuming fields is the bronze industry. Recommendations were made several years ago by the War Production Board toward the use of bronzes of lower tin content and manganese bronze and yellow brass for the customarily used tin-bronze alloys. The substitution of 88-5-5-2 copper-nickel-tin-zinc for composition G received considerable attention before the war, and consequently this alloy and modifications of it have been adopted for some current structural and pressure castings requiring high mechanical properties. Another of the commonly used bronzes is the 10 per cent tin 10 per cent lead copper alloy for heavy-duty bearings. It has been known for some time that about 2.5 per cent nickel could be substituted for an equal amount of tin with retention of equivalent casting and tensile properties; however, it was desirable that a still greater conservation of tin be made. Consequently the present paper deals with the development of an alloy of low tin content that could be used for bearings. Selection or Composition While the final criterion of the suitability of an alloy for a bearing must of course be determined by practical applications where all the ramifications of service conditions are encountered, certain short cuts in the initial selection of compositions are necessary to avoid an extensive and time-consuming investigation. The present program has been to match certain metallurgical properties of the 80-10-10 bronze that have been shown by previous investigations to be related to good bearing qualities. Such properties as microstruc-ture, hardness, compressive yield strength, ductility, and castability have been considered, and certain simple wear tests have been made. Of the readily assessed characteristics desired in a good bearing alloy, one can be certain that a uniform distribution of lead is required in a leaded bronze. It has generally been found that segregation of lead is one of the chief difficulties with this type of material. Tin has a powerful effect on lead distribution, and with 10 per cent present produces a random distribution of chunky particles, such as are shown in Fig' 1. I' In the tin bronze contains the hard alpha + delta

Jan 1, 1946

By John T. Eash

During the course of the war the supply of tin in this country has steadily decreased and a continued effort has been made since the beginning of the emergency to use alloys that are either tin free or contain appreciably lower quantities of it. Even with the use of emergency materials, the tin supply has become particularly acute, and it is estimated that after recovery of the far eastern mines probably one to two years will be required before our normal annual supply is attained. One of the major tin-consuming fields is the bronze industry. Recommendations were made several years ago by the War Production Board toward the use of bronzes of lower tin content and manganese bronze and yellow brass for the customarily used tin-bronze alloys. The substitution of 88-5-5-2 copper-nickel-tin-zinc for composition G received considerable attention before the war, and consequently this alloy and modifications of it have been adopted for some current structural and pressure castings requiring high mechanical properties. Another of the commonly used bronzes is the 10 per cent tin 10 per cent lead copper alloy for heavy-duty bearings. It has been known for some time that about 2.5 per cent nickel could be substituted for an equal amount of tin with retention of equivalent casting and tensile properties; however, it was desirable that a still greater conservation of tin be made. Consequently the present paper deals with the development of an alloy of low tin content that could be used for bearings. Selection or Composition While the final criterion of the suitability of an alloy for a bearing must of course be determined by practical applications where all the ramifications of service conditions are encountered, certain short cuts in the initial selection of compositions are necessary to avoid an extensive and time-consuming investigation. The present program has been to match certain metallurgical properties of the 80-10-10 bronze that have been shown by previous investigations to be related to good bearing qualities. Such properties as microstruc-ture, hardness, compressive yield strength, ductility, and castability have been considered, and certain simple wear tests have been made. Of the readily assessed characteristics desired in a good bearing alloy, one can be certain that a uniform distribution of lead is required in a leaded bronze. It has generally been found that segregation of lead is one of the chief difficulties with this type of material. Tin has a powerful effect on lead distribution, and with 10 per cent present produces a random distribution of chunky particles, such as are shown in Fig' 1. I' In the tin bronze contains the hard alpha + delta

Jan 1, 1946

By Eduardo Poltronieri Trés, Anderson Denadai Thomazini, Rodrigo Boyer Fernandes, Francisco de Assis Dutra Macedo, Gilvandro Bueno, Maycon Athayde, Rossano Augusto Pilon Nunes

The fundamental importance of comminution by high-pressure grinding roll (HPGR) technology to efficiently increase the particle surface area lies in lower energy and water consumptions for iron ore pellet feed production. This study compared the ball wet milling process with the innovative HPGR processing technology for hematite-goethite ores. Green-pellet balling and induration processes were simulated on the bench and pilot scales.

By Luis Roberto Zorzanelli

Esse trabalho tem como objetivo apresentar o projeto de melhoria da automação das pontes rolantes (PRs) e arranjo do pátio de bobinas BQ1, onde estão localizadas as linhas de acabamento (LAs)(Encruamento e Corte) como parte do projeto maior de aumento de produtividade destas plantas. Percebeu-se que a atuação na logística interna do pátio e na interface com as PRs poderia obter bons resultados nas movimentações de bobinas. O pátio tem áreas de recebimento e despacho de bobinas e quatro PRs e, portanto, grande número de movimentos possíveis, o grande desafio foi capturar estas informações e desenhar uma solução que atendesse as expectativas. Desta forma se buscou realizar um levantamento de dados minucioso para abrangendo o sistema existente, as características físicas e o modo operacional para definição de regras de movimentação otimizadas. As ações implementadas foram a revisão completa do arranjo do pátio e redefinição de regras de movimentação, e a implantação de terminal embarcado nas PRs para instruir as movimentações além de fornecer informações e dar autonomia para a tomada de algumas decisões controladas.

Aug 17, 2017

By R Coleman

The flotation mechanism plays a key role in the flotation process. It is used to provide the contact between solid particles and bubbles and also the energy for these particles and bubbles to attach. The mechanism must therefore provide sufficient mixing to keep the solids in suspension so that they can be transported into the froth and recovered to the concentrate. The design of the mechanism is critical and over the past decade Outotec has developed and optimised a new mechanism design to improve metallurgical and energy performance. The FloatForce® mechanism consists of a rotor and stator arrangement and has been specifically designed to provide sustained mixing at higher air flows and lower power inputs.Over 500 FloatForce® mechanisms have been installed in existing and new operations. This paper outlines the technological aspects of the FloatForce® mechanism and provides metallurgical, operational and energy performance results from a number of flotation circuits in which these have been installed.

Aug 8, 2011