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By H. Utsunomiya, J. Su, K. S. Tamimi, S. Yue, M. Sanjari, L. Kestens, A. S. Kabir, R. Petrov

The recrystallization and texture evolution of AZ31 sheets obtained through two stages was investigated at different stages of post-rolling annealing. The specimens were rolled at the temperature of 100? and at a fast speed of 1000m/min and low speed of 15m/min with a reduction of 30% in one pass. The results show thatAZ31B sheets rolled at 15 m/min and 100 °C has fractured for reductions of more than 30% per pass. However, by increasing the rolling speed to 1000 m/min the rollability was improved significantly and the material can be rolled to reductions of more than 70% per pass. The high speed and heavily deformed materials are fully recrystallized even at 100 °C.

Jan 1, 2015

By H. Utsunomiya, J. Su, K. S. Tamimi, S. Yue, M. Sanjari, L. Kestens, Hara, A. S. Kabir, R. Petrov

Manufacturing of thin sheet is difficult in industries. Some approaches, such as small-draft multi-pass rolling, intermediate annealing, isothermal rolling and high-speed rolling were proposed to overcome the deformability. In this study, different rolling speeds from 15 to 1000 m/min were employed to twin rolled cast AZ31B magnesium alloy to different reductions. The results show thatAZ31B sheets rolled at 15 m/min and 100 °C has fractured for reductions of more than 30% per pass. However, by increasing the rolling speed to 1000 m/min the rollability was improved significantly and the material can be rolled to reductions of more than 70% per pass. The high speed and heavily deformed materials are fully recrystallized even at 100 °C.

Jan 1, 2014

By Alcides Meléndez González

La formación profesional del personal minero es importante en tanto mejora su desempeño y responsabilidades con la empresa y actividad minero. En ese sentido, el presente trabajo describe los programas de educación profesional desarrollados por el Estado u organizaciones privadas a través de tres etapas: formación profesional elemental, formación profesional especializada y la formación profesional universitaria. Los principales objetivos son: adquirir los fundamentos técnicos, científicos y tecnológicos de la actividad minera y establecer mejores métodos de trabajo como nuevos procesos tecnológicos.

Nov 1, 1972

By Jorge Vargas Fernández

Con el objetivo de incrementar la productividad de la minería, se plantea la realización de una positiva acción nacional de formación y capacitación en todos los niveles de la industria minera a través de un análisis de la situación actual respecto de los mineros, ingenierios y técnicos. Por ello, el presente texto señala la descripción del sistema "B" en funcionamiento de la productividad minera y la tecnología adecuada a la realidad.

Nov 1, 1972

By M. Mustafa Kahraman, Sean Dessureault, W. Pratt Rogers

Most contemporary mines have considerable amounts of data. Structured and unstructured large data sets are colloquially named big data. Much of the data in mining operations come from a variety of systems, each with different databases and reporting environments. Standard technology deployments create a Bsilo-ification^ of data leading to poor system benefit. Through modern server monitoring and systematic approach, data utilization and value can quantifiably be measured. The Data Utilization and Value Index (DUVI) can quantify business intelligence best practices and user interaction. This study seeks to provide a data management tool to measure data utilization across the process of converting data into action.

This book has employed miners' narratives to illustrate basic concepts about the escape process. One of the most powerful means by which people make sense of their experiences is through the telling and internalization of stories [Bruner 1990]. By couching one's own and others' motives and actions in terms of a coherent narrative, a person is able to learn from mistakes and plan future behaviors that may help ensure survival. A growing body of research suggests that decision-making skills used to deal with emergency situations can be taught and assessed by simulations based on narratives from the real world [Bransford et al. 1986; Brecke 1982; Brener 1984; Connolly et al. 1989; Halff et al. 1986; Jones and Keith 1983; Lacefield and Cole 1986]. Such techniques have been used to address the decision-making of medical personnel, civil and military flight crews, and even people involved in broader life events such as political and military situations [Babbott and Halter 1983; Dugdale et al. 1982; Farrand et al. 1982; Gilbert 1975; McGuire 1985; McGuire et al. 1976; Flathers et al. 1982; Giffin and Rockwell 1984; Jensen 1982; Janis and Mann 1987]. Given the validity of this method of study and the promise it holds for helping people improve the quality of their responses to nonroutine occurrences, it is perhaps surprising that there have been no studies of emergency decision-making among blue-collar workers prior to those conducted by the present authors and their colleagues. The purpose of this chapter is to describe underground coal miners' decision-making performance on a table-top simulation whose problem structure is derived from interviews with a group of eight miners who escaped from the 5 Left section at Brownfield Mine. The exercise was constructed by a panel of domain experts (mine safety and rescue personnel) with the assistance of an educational psychologist. The simulation includes actual predicaments with wise and unwise decision alternatives that, in the opinion of these domain experts, are characteristic of such escapes. Results reported in this chapter are the scores of a sample of experienced mine workers who completed the simulation. Because the exercise is a series of objective performance tasks coupled with detailed and immediate feedback, this simulation can be used to teach and refresh critical escape skills, as well as to provide data concerning the proficiency of miners at the time of exercise administration.

Jan 1, 2000

By D Nourry

Optimising the blast is a major issue in the blasting business. It generally means acting on the blasting pattern (drilling, charging, detonating) in order to get a given æresultÆ. This result may either be related to economic reasons, such as the fragmentation influencing productivity, or technical reasons, for example vibrations and projections. Within the frame of the EEC funded Brite-Euram project entitled æBlast-ControlÆ, involving academic research and applied expertise, a general methodology was developed to approach such a problem and currently applied to the industrial partners of the project and final end-users of the generated results. These partners are the limestone ALZO quarry of the CALCINOR group in the north of Spain and the dolomite DMD (Dolomies-de-Marche-les-Dames) quarry of the LHOIST group in the east of Belgium. A first part of the project, over 18 months, was dedicated to establishing a clear relationship between productivity of operations from drilling to primary crushing and the fragmentation resulting from the blast. Extensive monitoring of blasting, production performance and fragmentation data was carried out and automatically collected into a database on both quarries. As expected, it appeared that excessive amounts of fines or boulders were substantially reducing productivity and thus profitability of the operation. Furthermore, an æoptimalÆ fragmentation was assessed for the quarries to run at the best (high throughput, low cost). The second and last part, for the remaining 18 months, was then dedicated to adapting the blasting practice in order to orientate the fragmentation towards a æbetterÆ one. A very common problem normally addressed by any consultant. Nevertheless, the target was not limited to solving the problem for these two quarries, but also to develop a generic method to address this blasting adaptation process and to implement it into a computerised tool. At this stage, it is then obvious that portability of the method and the system are major qualities to be looked for. This paper is aimed to present how this method was developed, how the system was implemented and how it was finally used.

Jan 1, 2001

By José Calderón

Frente a la ausencia del Estado en el distrito de Pataz (La Libertad, Perú) —donde Poderosa tiene sus operaciones— existe una presión por parte de la población hacia la empresa para cubrir el déficit de agua de consumo humano. Por ello, se implementó un proyecto, con los anexos de Pueblo Nuevo, Zarumilla y Chuquitambo como ámbito de acción, cuyo objetivo principal era la formalización de la gestión de agua de consumo poblacional, de tal manera que la población disponga de agua de calidad, a la vez que se prevenga y reduzca la conflictividad socioambiental. En el presente documento se exponen las principales actividades realizadas como parte del proyecto, así como los resultados obtenidos.

Sep 20, 2019

By Pedro Hugo Tumialán de la Cruz

La distribución espacial de los minerales como efecto a ciertas condiciones físicas y geológicas del terreno se conoce como zoneamiento. El conocimiento de este proceso permitirá la planificación de un programa de exploración para una futura explotación. En este sentido, el presente texto señala las formas geométricas de zonamiento encontradas en los yacimientos hidrotermales del Perú a través del empleo de diversos métodos geológicos como el método de distribución minerológica, isovalores de leyes, cocientes métalicos, así como el método de trazas en casos especiales.

Nov 20, 1978

By Carl Swartz

METALLURGISTS differ considerably in their opinions regarding the effect, if any, of small amounts of iron pyrites, or other iron compounds on zinc sulfide ores during the roasting operation. As a result, the literature on this subject expresses many conflicting ideas. The ore, previously crushed to pass through a one-millimeter screen, dries in the roasting kiln, losing water up to 200° to 300° C. At 150° C. iron pyrites begin to lose sulfur. As the temperature increases, while the ore is passing to the hotter part of the furnace, the sulfur burns to sulfur dioxide, leaving the metals as zinc oxide and ferric oxide. These two substances then interact to form zinc ferrite, a compound, yellow brown in, color, having the general characteristics of a spinet Like magnetite, another spinel, zinc ferrite is insoluble in alkalis and dilute acids. As a result, when leached with 10 per cent. sulfuric acid solution zinc values tied up in this compound remain behind. HISTORY In the electrolytic recovery of zinc from its ores, the roasted ores are usually leached with a 10 per cent. sulfuric acid solution. When the zinc ore contains iron pyrites as an impurity in an appreciable amount, the actual yield of metallic zinc is much lower than a theoretical calculation would indicate. Further, losses of zinc are, in a rough way, directly proportional to the amount of iron pyrites or other iron compounds present. When the iron is present in the ore in an isomorphous relation to the zinc, as in the case of a marmatite, a greater amount of zinc remains insoluble than when present as a true pyrite or marcasite. Work on the insoluble residues obtained from leaching of the calcines shows that the zinc lost is intimately tied up in this residue. Some investigators have suggested a definite compound, such as zinc ferrite, others merely a mixture of zinc and iron compounds.

Jan 1, 1927

By R. K. Clifford

The formation of elemental sulfur on the surface of sphalerite in aqueous systems was investigated. Hallimond tube flotation tests showed that unoxidized sphalerite did not float well without a collector. Flotation recoveries of greater than 95 percent were obtained without the use of a collector or frother after the sphalerite had been reacted with oxygen under pressure and water at pH 2.8 at room temperature. High flotation recoveries also resulted when sphalerite was reacted in acidic solutions in the presence of platinum sponge, titanium sponge, 316 stainless steel, copper turnings, or [10-5M++]. Conditions which produced high flotation recoveries of sphalerite yielded contact angles of 37° to 40° and also produced elemental sulfur. The increase in elemental sulfur on the surface of sphalerite was detected by elemental sulfur extraction with petroleum ether, electron spectroscopy for chemical analysis (ESCA), and the electron beam microprobe. The quantity of elemental sulfur formed was insufficient to be detected by infrared or Raman spectroscopy, or by the optical microscope or by the scanning electron microscope. An electrochemical type reaction for the production of elemental sulfur in acidic solutions was proposed. The cathodic reduction of oxygen was the slow step which needed to be catalyzed. A chemical type reaction which produced H2S rather than elemental sulfur was evident in non-oxidizing conditions.

Jan 1, 1974

By A. Jowett

An attempt is made to explain differences in the size-by-size response to flotation of some sulphide minerals. Physical factors involved in particle-bubble collision and adhesion, and also in possible subsequent disruption of aggregates, are considered especially in relation to flotation of the coarser sizes. Emphasis is on practical observations and their significance, with an essentially qualitative theoretical treatment designed to form hypotheses for further experiments. In particular, the theoretical effects of contact angle and induction time are examined. An argument is developed which suggests a rapid increase in induction time as particle size increases, except for particles small enough to be moving under laminar flow conditions. This can adequately explain poor recoveries of coarse particles in flotation without a need to assume disruption of particle-bubble aggregates in turbulent zones in a flotation cell. Flotation recovery is shown to be very sensitive to small changes in induction time. Consideration of the physics of disruption of particle-bubble aggregates leads to the conclusion that this mechanism does not adequately explain differences in flotation recovery of coarser sizes of some sulphide minerals. For example, to explain differences in recovery of coarse galena and chalcopyrite by this mechanism would necessitate accepting that conditioning with ethyl xanthate which would promote a 60º contact angle at a galena surface would promote only an 11º angle at a chalcopyrite surface. Small differences in induction time arising from differences in surface chemical characteristics of the various minerals offer a more satisfactory explanation of differences in recovery of coarser sizes.

Jan 1, 1980

By G. C. Yao

Iron and silicon impurities can form needle and branch shape intermetallie compounds in molten aluminum when there is no manganese. It is difficult to separate them from molten aluminum by electromagnetic separation. The Fe-Si-AI and Fe-Al intermetallic compounds were transformed into Mn-Fe-Si-Al and Mn-Fe-Al compounds by the addition of manganese into molten aluminum. In molten aluminum the morphology of these intermetallic compound particles is lumpish and spherical. Migration resistance of these impurity particles is small, which is beneficial to separation. FeSiMnA4 and FeMnAI6 are paramagnetic. These impurity particles can be moved by magnetic force and can be separated from the molten aluminum.

Jan 1, 2003

By G. C. Yao

Iron and silicon impurities can form needle and branch shape intermetallie compounds in molten aluminum when there is no manganese. It is difficult to separate them from molten aluminum by electromagnetic separation. The Fe-Si-AI and Fe-AI intcrmetallic compounds were transformed into Mn-Fe-Si-AI and Mn-Fe-AI compounds by the addition of manganesc into molten aluminum, In molten aluminum the morphology of these intermetallic compound particles is lumpish and spherical. Migration resistance of these impurity particles is small, which is beneficial to separation. FeSiMnAl4 and FeMnAl6 arc paramagnetic. These impurity particles can be moved by magnetic force and can be separated from the molten aluminum.

Jan 1, 2003

By Charles H. Moore

In the study of the properties of rutile pigments it became apparent several years ago that certain physical and optical properties could not be determined on particles of pigmentary size. Since reflected light is the dominant type which reaches the eye from small particles, the true color of pure rutile was not known. Most rutile pigments are acicular in habit, elongated parallel to the "c" axis. It was considered important to know the nature and tone of light transmitted, for example, by a basal plate. Further, as shown by spectrophotometric curves, there is a very strong absorption of light of 4000 k as measured on particles with random orientation. It would be interesting to see whether this absorption position varied with predetermined and selected orientations. Also, since the behavior of titanium pigments in a vehicle is important, a knowledge of the surface wettability of single crystals by various media should prove very fruitful. Finally, the optical properties of rutile are such that it should show, in a single pure crystal, greater fire and brilliance than the diamond. Mineralogists had long speculated that this would be the case and curiosity was strong to produce a single crystal large enough to cut.

Jan 1, 1949

By Gerhard Bayer

X-ray and thermoanalytical studies were carried out on the formation and stability of Ca-, Mg-and Mn-tungstate, and of the corresponding minerals scheelite and wolframite. The tungstates were synthesized by different methods: precipitation from solution, solid state reactions, displacement reactions with solutions and in the solid state. The reactivity of natural scheelite and wolframite with different salt solutions and in mixtures with other minerals was investigated.

Jan 1, 1989

By Hye-Sung Kim, Dong-Wha Kum, Gyeungho Kim

"Mechanical alloying is an effective way to finely distribute inert dispersoids in AI-TM (TM is a transition metal element) systems. It is considered that high melting point aluminides are formed by precipitation from the supersaturated aluminum matrix. The analysis is based on the fact that much higher content of TM than the solubility limit can be dissolved in alpha aluminum during the high energy ball milling. Nonetheless, the role of undissolved TM particles affecting the formation of aluminides is not suitably considered. In this paper, authors present experimental observation on the formation of Ab3Ti particles from mechanically alloyed AI-Ti alloys in the hyper-peritectic region. This study showed that, in the mechanically alloyed AI-20wt%Ti specimen, intermediate phase of cubic Ab3Ti and tetragonal AIz4Tis formed at 300 - 400°C and 400 - 500°C, respectively, before the MA-state reaches to the global equilibrium at higher temperatures. The formation behavior of Lh- Ab3Ti is interpreted by interdiffusion of Al and Ti in solid state based on the fact that large amount of nano-sized Ti particles exist in the milled powder. Present analysis indicated undissolved Ti particles of nanosize should have played an important role initiating the formation of Ab3Ti phase during annealing.IntroductionInterest in the hyper-peritectic AI-Ti alloys is based on industrial demand for high-modulus and high-temperature aluminum alloys. Earlier works on hyper-peritectic AI-Ti alloys with 4 to 12wt%Ti show that these alloys are strong at ambient temperature and maintain high strength above 300°C when titanium-trialuminide (e.g., Ab3Ti) is finely distributed in the aluminum matrix [1,2]. High melting point and high stiffness with low density of AbTi make the AI-Ti alloys strong with greater thermal stability while keeping weight savings as much as possible. Titanium in aluminum shares other merits of transition metal additions because Ti solubility in Al is low (i.e., 1.l5wt%Ti at 665°C and virtually zero below 400°C), and fine dispersion of Ab3Ti particles is readily accomplished and resists grain coarsening effectively."

Jan 1, 1996

By M. Lu, E. Broch

Abstract: The formation and mechanism of rock cavern roof arches are studied and effects of rockbolts reinforcement are evaluated. It is concluded that a self-supported roof arch may be formed by the excavation. To stabilize such a roof arch, fully grouted rockbolts are effective. Tensioned cable anchors may have a negative influence on the arch stability. Zusammenfassung: Die Formation und der Mechanismus von Deckenbögen in Bergkavernen wird studiert und der Effekt von Verstärkung mit Bergbolzen wird bewertet. Es wird festgestellt, dass die Exkavation einen selbst-stützenden / freitragenden Deckenbogen formen kann. Eingegossene Bergbolzen sind effektiv um einen solchen Deckenbogen zu stabilisieren. Spannkabel können unter Umständen eine negative Einwirkung auf die Stabilität des Bogens haben. Résumé: Le mécanisme et la formation de voûtes dans les cavernes rocheures sont étudiés et l'effet du renforcement par boulonnage est évalué. Nous arrivons à la conclusion qu'une voûte autosupportêe peut être formée par excavation. Des boulons entièrement scellés par coulis de bêton s'avèrent efficaces pour stabiliser de telles voûtes. Les tirants d'ancrage peuvent quant à eux nuire à la stabilité de la voûte.

Jan 1, 2003

By Seong-Jong Kim

The formation behavior and corrosion characteristics of anodic oxide films on pure Mg and Mg-AI alloys were investigated focusing on the effects of anodizing potential, Al content, temperature and NaOH concentration. Pure Mg and Mg-AI alloys were anodized for 10 min at 3, 10, 40, and 80 V in NaOH solutions. Mg(OH)2 was generated by an active dissolution reaction at the surface of the specimen and the product was affected by temperature while MgO generation increased with NaOH concentration. Moreover, the current density after anodizing for 10 min at a constant potential decreased with increasing AI content in Mg-AI alloys,

Jan 1, 2003

By Chen Shuwen, Yao Zhihua

In the process of thickening dewatering_the motion state of two- phase flow in a thickener has a very great influence on thickening efficiency. The investigation was made using copper mill tailings. In this investigation the authors explored the formation conditions and motion range of density current in the thickening process by model experiments, and analyzed the influence of density current on thickening efficiency. The results have shown that the formation of density current has relations with the structure parameters of a thickener and thickening process. The density current and its forming location affect thickener’s working efficiency. The author measured the motion state of two- phase flow in a 53-m dial. thickener for copper mill tailings under its operation conditions and analyzed the density distribution and motion state of two-phase flow in the thickener. The results obtained by the industry tests have shown that the motion state of two- phase flow in the thickener can be greatly improved by modification of its structure, achieving a great improvement in its thickening efficiency. It is concluded that, a thickener’s working efficiency depends on the formation and motion range of density current in it, which is of great importance to designing and establishment of thickener’s working parameters.

Jan 1, 2003