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By Vinícius Cunha de Souza

Dispositivos atuatores com componentes de ligas de NiTi podem ter seu desempenho modificado quando submetidos a distintas taxas de aquecimento e/ou resfriamento resulte numa transformação de fase. Por outro lado, por norma, as temperaturas de transformação de fase (início, pico e fim) devem ser estabelecidas a partir de taxas fixas de 10ºC/min (tanto no aquecimento como no resfriamento) através da técnica de Calorimetria Diferencial de Varredura (DSC), sem levar em conta a dinâmica do material durante a transformação em aplicações reais. O presente trabalho procura observar a transformação de fase do material avaliando a capacidade de resposta do mesmo, quando submetido a ciclos em um DSC sob diversas taxas de resfriamento e aquecimento, entre 1 e 10ºC/min em uma liga de NiTi rica em Ti, com formação de fase R durante o resfriamento e/ou aquecimento. Os resultados de DSC foram submetidos a um tratamento de dados com o intuito de melhor determinar as temperaturas de transformação de fase associadas as frações transformadas. Pode-se verificar que valores de taxas de resfriamento e de aquecimento superiores a 7°C/min permitem que ocorra uma tendência para um incremento do intervalo entre as temperaturas de início e fim das transformações direta e reversa.

Aug 16, 2017

By A. R. Biggart

Twenty-sixth Sir Julius Wernher memorial lecture, presented at the Tunnelling '94 symposium held in London, 5-7 July 1994. In describing 18 projects with which he has been involved over a period of 36 years, the author aims to illustrate how technological change and an increase in scientific knowledge have influenced tunnelling practice, which he nevertheless maintains does continue to be an art. Tunnels discussed are: the Silver Street, Blackfriars, Whitechapel, St. Paul's and Waterloo Post Office tunnels, 1958-1969; metro tunnels on the Victoria Line, London, 1962-1970; the introduction of tunnel boring machines (TBMs), 1971-1978, in the Empingham reservoir diversion tunnels in Rutland, the bentonite tunnelling machine experiment at New Cross, the Southern tunnel water main section of the London Ring Main and the Warrington sewer in Cheshire; tunnels in rock 1975-1981, for the Lune Wyre and Megget Manor aquaducts, Weymouth sea outfall and Bristol interceptor sewer; Priestley TBM tunnels 1969-1982; the Greater Cairo wastewater project 1983-1987; Anacostia River crossing, Washington DC 1985-1987; the Channel Tunnel 1987-1992; and the Storebaelt eastern tunnel in Denmark, 1992-1994.

Dec 1, 1994

By G. Lyle

Since its inception CEMI (Centre for Excellence in Mining Innovation) has focused on facilitating innovative solutions to the mining industry in six strategic research areas; GeoRisk, ConstructMine, ValueMine, FindMine, SustainMine and MineTech (visit www.miningexcellence.ca for details). This paper focuses on CEMI?s largest project to date, Ventilation on Demand (VOD). Energy consumption in mines can account for upwards of 40% of a mines operating cost, with a significant portion of this been consumed by the ventilation requirements. VOD provides a significant opportunity to reduce overall mine ventilation requirements and subsequently energy costs, while potentially increasing mine productivity. CEMI is currently in year 2 of an assessment of VOD, focusing on the financial, physical and equipment viability of utilizing such systems in both new and existing mines. This two year program, to be completed by March 31, 2011, is designed to systematically assess such a system to determine if and when it could effectively be applied in underground mines. The paper will describe the process by which the project was initiated, the demonstration projects established to capture data, the means to interpret the data and the modelling developed to calibrate and predict ventilation system requirements.

Oct 1, 2010

By Dennis R. Dolinar, John L. Ellenberger, Gabriel S. Esterhuizen, Anthony T. Iannacchione

A survey of pillar conditions was carried out at 21 operating limestone mines that use the room-and-pillar method. The surveyed pillars were all located in rock that was classified as “Good” to “Very Good” using the RMR rock mass classification system. The average pillar width was 14.5m and the width to height ratio varied between 0.53 and 3.52. Pillar conditions were rated using a visual rating system that accounts for the effect of geological structures as well as stress related fracturing. Nine cases of pillar instability were recorded. Pillar instabilities were typically limited to individual pillars or small groups of pillars within an otherwise stable layout. Local geological structures such as inclined discontinuities or weak bedding planes contributed to instability in seven of nine cases that were observed. Elevated pillar stresses contributed to instability in the two remaining cases. All the unstable pillars observed had width-to-height ratios of less than 1.5. It is concluded that pillar instability is most likely to be caused by unfavorable geological structures in pillars with width to height ratios of less than 1.5. Stress related instability such as rib spalling becomes more prevalent when the average pillar stress approaches approximately 20 MPa.

By Jorge Olivari Ortega

El presente texto señala la relación del inca Huayna Cápac con las arenas auríferas de Chuquimayo. Huayna Cápac, hijo de Túpac Inca Yupanqui y Mama Ocllo, fue el décimoprimer inca gobernante del Tahuantinsuyo (¿1493- 1527) que ordenó construir una estatua de oro puro, similar al del cuerpo de su madre ya muerta,en Mullucancha. Asimismo construyó adoratorios para los dioses Inti, Huiracocha e Illapa, a los cuales dotó de tierras, ganado y personal de servicio. Luego se casó con Cusi Rimay y retorna a Quito y Cuzco. Posteriormente muere Cusi Rimay y se casa con Rahua Ocllo, futura madre de Huáscar. Inicia una nueva campaña militar hacia el Collasuyo, llegando a la región de los Charcas, pasa a Chile y regresa a Cusco. De otro lado, en uno de los viajes de reconocimiento a tierras peruanas de Francisco Pizarro, Yupanqui se informa y ordena el traslado de los españoles a Tumibamba. En ese contexto, Diego Palomino, uno de los españoles en llegar, realizó un croquis de la zona yacimientos auríferos de importancia, ubicados en el territorio de los Pucamurus, son los de Tomaque, Aconipa, Picorana, Quipe y Santa Agueda, que no son explotados actualmente por falta de recursos hídricos.

Jul 1, 2016

Ammonium nitrate-fuel oil (ANFO) explosives are unstable in hot, reactive sulphide-rich ground at Mount Isa. Under certain conditions associated with background heat, moisture, and chemical impurities from natural oxidation, ANFO composites in contact with hot ground disproportionate and the ammonium nitrate can undergo rapid exothermic reactions with sulphide.Reactions can occur in confined charges from prolonged contact with reactive sulphides, or by contamination with sulphide in loading. Partial interaction can result in misfires or premature detonation. Spilt, scattered and unpropagated explosive will undergo further reaction in sulphide-rich environments. ANFO-sulphide interaction is invariably exothermic and causes an irreversible chemical transformation of the ore.The heat generated during reaction may be dissipated, heating the environment, or rapidly accumulated to yield hot spots or areas in excess of 400°C. These can result in forced ignition of bulk sulphide and sustained combustion.Thermal analysis was used to define the critical conditions for ANFO-sulphide interaction and sulphide combustion.The occurrence of incandescent ore is attributed to the thermal interaction between exothermic hydrolysis oxidation, ANFO-sulphide, and combustion processes.Chemical agents and control methods have been developed to prevent ANFO-induced oxidation and combustion.

Jan 1, 1968

By C. Hutton

"SynopsisThe last commodities supercycle (2003 to 2011) was characterized by a belief in volume at any cost, where absolute output was deliberately prioritized over productivity considerations. This practice fuelled overoptimistic forecasting and planning, which in turn contributed to the economic crisis that followed. The sudden collapse of commodity prices has resulted in mining companies scrambling to find the right balance between optimizing current operations and preserving sufficient flexibility to grasp future opportunities. The runaway costs of building and operating mines have almost squeezed out profit margins, while lower ore grades are inflating production costs. Mining companies therefore need to look at the business with fresh eyes, and develop strategies to attract equity capital as traditional approaches are simply not working anymore. This is especially so in the context of a dwindling investor base that continues to demand greater returns, despite a significantly lower appetite for risk. This paper revisits the micro-economic concepts and demonstrates how pressure from shareholders to prioritize output contributed to spiralling costs and value destruction. Practical techniques are described to model cost curves to optimize a Mineral Resource endowment and address the need to rightbalance a business and preserve agility.IntroductionHenry Lazenby (2014) for the Mining Weekly writes, ‘Bruised and battered, the global mining industry today is undergoing a sea change. Practices and policies that might have worked wonders in the past are not as relevant today, and new approaches to running profitable mining operations need to be found.’ One significant practice the mining industry had during the last commodities supercycle (2003 to 2011) was chasing volume at any cost; absolute output was deliberately prioritized over productivity considerations (Goldsmith, 2013). Lazenby contends that in the face of falling and volatile commodity prices, many mining majors ‘across all commodity groups are currently grappling with sagging profits and low company valuations. This is often regarded as the result of the were in pursuit of growing their output at all costs in a high commodity price environment.’ Lee Hodgkinson, KPMG’s Canadian mining industry leader and quoted by Lazenby, says that ‘mining companies are now trying to find the right balance between optimizing current operations and preserving their agility to grasp future opportunities. The runaway costs of building and operating mines have almost squeezed out profit margins [whilst] lower grades of ore are inflating production costs. Mining companies need to look at the business with fresh eyes, and develop strategies to attract equity capital as it seems clear that some of the traditional approaches to the mining business are simply not working anymore."

Jan 1, 2015

A compilation of papers presented at The Second WVU Conference on Coal Mine E1ectrotechnology in Morgantown, West Virginia on June 12 -14, 1974. Papers cover areas of electric power, electronic communications, detection and location of trapped miners, and electronic sensors and monitoring systems.

Jan 1, 1974

By S. Lolon

Spontaneous combustion in underground coal mines has become a serious problem particularly in the caved area (gob). Recent statistic has shown that approximately 17% of total 87 underground coal mine fires in the United States are attributed to spontaneous combustion (De Rosa, 2004). Spontaneous combustion results from a self-heating process in exothermic conditions. The accumulated heat, if not removed, is conducive to the rapid increase of temperature and may result in mine fires or explosions. It is well accepted that the interaction between oxygen and coal substances is the main cause for spontaneous combustion, while other factors such as pyrite, moisture, and bacteria play a secondary role to the self-heating of coal. Therefore, only coal oxidation is considered in this study. Coal oxidation occurs as coal comes into contact with air. This process involves complex phenomena in terms of heat transfer, chemical surface absorption, and energy balance related to inherent properties of coal (Wang et al., 2003). For simulation purpose, overall reactions can be simplified as suggested by Mitchell (1990): C + O2 CO2 + heat [65°- 94°C] (1) CO2 + C 2CO + heat [100°- 150°C] (2) Stoichiometric reactions (1) and (2) show that 2.66 grams of oxygen are required to oxidize 1.0 gram of carbon. Once the temperature exceeds 100°C, the reaction has little chance to stop. The crucial step in reducing spontaneous combustion risk is locating the ignition point of spontaneous combustion (hot spot). This information is useful in the effort of developing a preventive method effectively. In this study, this was conducted based on the best gathered information: ventilation surveys conducted in an existing longwall mine located in the western US; the laboratory experiments performed on a physical gob model; and the CFD models to investigate the flow behavior in the gob, the oxidation of coal, and heat transfer phenomena. The hot spot location is determined as a function of oxygen concentration and gob temperature. The critical values are the following: 5% (by volume) for oxygen and 100°C for gob temperature. CHARACTERISTICS OF GOB MATERIAL AND MODELS Permeability Concept Permeability is one of the key parameters in any study dealing with porous medium. This is determined by particle size and the ratio of void volume to the total volume (porosity) of porous medium. This relationship is known as the Carman-Kozeny equation (Scheidegger, 1957) and is given mathematically as [ ] where k* = theoretical specific permeability, m2 dm = the mean particle size, m n = porosity However, permeability tests with various particle sizes were carried out at the University of Utah?s ventilation model (Figure 1) to verify this relationship. These tests indicated a necessity to modify this theoretical relationship. A factor of 0.898 was obtained to make up the different between theoretical permeability and the experimental one. The modified version of (3) is given by: [ ] This equation is used to determine permeability of the simulated mine gob throughout the study. [ ] Mine Gob Material The gob is represented by zones filled with material of given size distribution. For physical measurements and CFD simulations, the material used were crushed rock and coal. Due to compaction, three different characteristics of gob material were used in the model: unconsolidated, semiconsolidated, and consolidated. In the real condition, the largest coal-rock particles are more likely to be located in the area behind the shields. This material is freshly broken and unconsolidated. The size of these broken particles is based on a study carried out by analyzing images taken from the area behind the shields in three coal mines in the United States (Pappas and Mark, 1993). The results have shown that the mean size of materials behind the shields is about 1.22 m. The permeability associated with this size was then obtained from (4) and permeability tests. This was 4.68 x10-7 m2. For semiconsolidated and consolidated zones, due to the lack of experimental data, these were determined through CFD simulations. These simulations were designed by assigning a permeability of 3.15 x 10-8 m2 for consolidated zone and 7.98 x 10-9 m2 to the other zone. The airflow pattern in the gob assigned with given permeabilities was expected to follow the experimental distribution (Brunner, 1985). The mean particle sizes for the semi-consolidated and consolidated zones were 0.02 and 0.006 m, respectively; smaller than those of the unconsolidated zone. Figure 2 shows the 3D view of permeability changes in the gob.

Jan 1, 2009

By D. L. Russel

El hidrociclón tiene una función importante en las operaciones auxiliares del beneficio de minerales, ya que separa los sólidos suspendidos de la pulpa de alimentación en dos fracciones, eliminando las partículas nocivas. Por tal motivo, el objetivo del texto describe ejemplos de ciclones activos en las concentradoras de la mina de Cerro de Pasco, como sus características. Los ciclones desarrollan tres clases de trabajos: la clasificación en circuito cerrado o de molienda, deslamamiento antes de flotar y el espesamiento y deslamamiento al circuito de filtración. El primero ejemplo, se realizó en la concentradora Paragsha con remolienda de cobre, el segundo se relaciona con flotación de pirita y el último, con filtración de cobre y zinc en la concentradora de Huarón. Producto de esta revisión a los ciclones, se encontró que la facilidad y costo de fabricación de aparatos experimentales, flexiblidad en el uso, comodidad de instalación y el poco espacio requerido, condicionan el uso del hidrociclón en varias operaciones de clasificación y espesamiento al tiempo que reemplazarán las clasificadoras clásicas por circuitos de molienda primaria

Jul 20, 1960

By A. H. G. Mitchell

Most, if not all, of the six recognised post-Cretaceous, predominantly andesitic mineralised belts in the region are now thought to be subduction-related magmatic arcs. The Inner Carpathian arc and the Eastern Bosnia or Drina-Rhodope arc host numerous vein and replacement deposits with epithermal features and Zn-Pb+/-Ag as the predominant economic minerals. In contrast, the south Apuseni Mountains have produced over 1 600 t Au from epithermal veins but very little Zn-Pb. Recent age determinations and geophysical data from the Baia Mare district of the Inner Carpathians suggest that mineralisation succeeded volcanism by 1-2 m.y. and accompanied crustal extension and the cooling of a large, mushroom-shaped pluton whose boundaries define the mineral district. In the south Apuseni district, mineralisation can be explained by mixing of meteoric with low-salinity metamorphic water expelled during intrusion of mafic rocks into the middle or lower crust. The more continental or cratonic crust in the Drina-Rhodope and Inner Carpathian arcs precluded the input of low-salinity, Au-bearing metamorphic water; the Zn-Pb deposits formed where convecting meteoric water mixed with saline water, possibly introduced through carbonate rocks in the basement

Aug 1, 1996

By B. P. Watson

The Bushveld platinum group metal deposits are two distinct, shallow-dipping stratiform tabular orebodies and strike for many hundreds of kilometres. Mining is extensive, with depths ranging from close-to-surface to 2 000 m. The mining method is a variation of planar open stoping. Pillars are widely used to support the openstopes. Little work has been done in the past to determine pillar strength and pillars have been designed using experience and formulae developed for other hard-rock mines. This has led to oversize pillars with consequential loss of ore or undersize pillars resulting in potential collapses or pillar bursts. This paper describes a back-analysis of pillar failures at Impala Platinum, just north of Rustenburg, and provides insights into pillar behaviour. Strength formulae are presented for Merensky Reef pillars at Impala. These formulae may be used cautiously on other platinum mines with similar geotechnical and geomechanical conditions.

Jan 1, 2008

By T Grenne, R. B. Larsen

Paper presented at the conference on Economic geology in Europe and beyond II, models for mineral deposits in sedimentary basins, held in Keyworth, UK, 13-14 April 1994. Paper originally entitled: Processes in a newly discovered sulphide-PGE mineralisation in Norway. The Stormyrplutten mineralisation is hosted by a minor tholeiitic metagabbro of low-Ti composition intruded at a high level in the volcanic lithology. It is thought to be the subvolcanic counterpart of submarine basalts generated during an extensional episode of ensimatic arc evolution. The sulphide-PGE mineralisation occurs as stratabound pyrite, pyrrhotite and chalcopyrite disseminations with average grades of 376 ppb Pd, 313 ppb Pt, 40 ppb Au, 0.5% Cu and 0.08% Ni in a deposit 15-25 m thick. Locally the PGE content peaks at 2 ppm over 1 m. Microprobe analysis isolated 14 different platinum-group minerals, dominated by sperrylite, temagamite and borovskite and occurring as 1-20 micron compounds embedded in the main sulphide minerals or along the sulphide/silicate grain boundaries. Mantle-normalised plots reveal strong depletion in Os, Ir and Ru and enrichment in Pt, Pd, Cu and Au. The general decrease in Pd and Pt and increase in S up through the stratigraphy is similar to PGE distribution in the Darwendale subchamber of the Great Dyke in Zimbabwe, and may reflect strong fractionation of Pd and Pt in favour of the first droplets of sulphide melt; two reversals of the trend at the 4 and 12 metre levels represent replenishment with fresh magma and repetition of the cycle. In contrast to the Darwendale system, Cu and Ni also show peak concentrations in the first-formed liquids and Pt appears to have fractionated more strongly into the sulphide melt than Pd

Aug 1, 1995

By E. LaRocque

"Long term contracts requiring delivery of 6,000,000 pounds of U308 per year to its customers have made it necessary for Denison Mines to expand its milling capacity from 7,100 tons per day to 15,000 tons per day.Previous papers (1) and (2) described the old leaching and product recovery practice. The flowsheet briefly includes a crushing and grinding circuit, sulphuric acid leaching in a Pachuca plant, liquid-solid separation with wash thickeners and two-stage drum filtration, concentration and purification by moving bed ion exchange followed by two-stage precipitation to produce an ammonia yellowcake.No. 1 Shaft ore, about 4,000 tons per day, will be processed through the truck dump into the old crushing and grinding plant and through the old leaching plant. Ore from Stanrock (No. 3 shaft) will be hauled by truck and also processed through the truck dump as No. 1 shaft ore. Beginning in 1982, ore production from Stanrock will gradually increase until 1985 when some 3,000 tons per day will be milled from the source.A new 8,000 ton per day circuit was designed and constructed to increase the milling capacity to 15,000 tons per day. The new circuit is separate from the old one except that it coins together for the precipitation and tailings neutralization sections of the plant. The feed to the new plant will be from No. 2 shaft.The flowsheet is much the same as the old plant with the exception of the grinding circuit and the ion exchange plant. A semi-autogenous grinding (SAG) plant, unique in the Elliot Lake area, has been installed rather than the conventional crushing and grinding plant; the ion exchange plant is the stationery bed type.This paper describes the major equipment installed for the expanded grinding and hydrometallurgical plant."

Jan 1, 1982

Ore from the Hill 50 Gold Mine, consists essentially of pyrrhotite, with minor amounts of pyrite, chalcopyrite, galena and gold, replacing "jaspilite." The gold is associated with the sulphides as shotty particles. About 8 per cent. of the particles are less than '0.010'mm.The Hill 50 Gold Mine, at Boogardie in the Murchison goldfield, about 300 miles north-west of Kalgoorlie, was first operated in 1898. From 1898 to 1917 it yielded 20,000 short tons of ore for a recovery of 6,225' fine oz. gold, equivalent to a recovery grade of 6.22 dwt. gold per ton.The present company since the beginning of its operations in September 1936 to June 30, 1954, produced 811,081 short tons of ore for a recovery of 242,554 fine oz. of gold, equivalent to a recovery grade of 5.98 dwt. gold per ton.The grade of ore (recovery grade) has shown a remarkable variation with depth. From the 120 ft. Ievel to the 300 ft. level, it averaged about 7.5 dwt. Au per ton. Below the 300 ft. level it declined, and from 300 ft. to 400 ft. averaged 4.9 dwt. per ton, falling further with increasing depth to about 4.5 dwt. per ton at the '600 ft. level.On the 820 ft. level the grade improved sharply to about 14 dwt: per ton, and this grade has persisted down to and on the 1060 ft. level.The orebody has been described by Finucane (1953) as a series of lenses of finely banded jaspilite conformably enclosed by greenstones. The jaspilite is tightly folded and faulted and intruded by dykes of felspar porpnyry.Mineralization is practically restricted to the jaspilite.

Jan 1, 1955

By Kevin W. Cargill

In September 2004, Hurricanes Frances and Ivan caused the Pigeon River in western North Carolina to flood. This flooding eroded the embankment below Interstate 40 (I-40) and sent one of the eastbound lanes, along with the roadway shoulder, into the river below the embankment. North Carolina Department of Transportation (NCDOT) needed to reopen all the lanes of I-40 as soon as possible and considered this damage to be an emergency situation. NCDOT contracted Schnabel Foundation Company to design and build a repair that would keep this important interstate open and reestablish the eastbound lane. The obstacles included limited work room, the requirement of keeping the remaining lanes of I-40 in service, and producing a final product that would be relatively maintenance free and last at least 100 years. The proposed repair had to consider that the existing interstate was founded on a rock fill that was constructed from rock blasted off the adjacent mountain side. The selected design included two, tied-back micropile walls to address these obstacles and other issues. Each of the walls were constructed of 10.75 inch diameter micropiles and corrosion-protected tieback anchors installed through the existing rock fill into competent bedrock, concrete wales, and a reinforced shotcrete facing. This successful project was completed during the coldest months of the year and within the timeframe established by the State of North Carolina. This paper will discuss the design and construction of the repair and the many challenges that had to be overcome.

Jan 1, 2006

By D. R. Parrish, F. F. Craig

In some respects, forward combustion (alias: fie-flooding, underground combustion, in-situ combustion, dry combustion) is an efficient oil recovery method. For example, its displacement efficiency (as much as 95 percent in reservoirs with high porosity and high oil saturation) is good. In its use of heat, however, forward combustion is grossly inefficient. Most of the heat generated during forward combustion is wasted. About one-fifth of the heat is picked up by the incoming air and re-used (regenerated); the remainder is left behind the combustion zone and ultimately is lost. Compressed air is expensive, and heat generated from compressed air via underground combustion is too valuable to be thrown away. Improvement is needed. Since the early 1950's, improvements in forward combustion by addition of water injection have been discussed, particularly in the patent literature, with increasing frequency.'-'' These concepts are based on the fact that relatively inexpensive water can be used to pick up much of the heat that is ordinarily wasted during forward combustion, and transport it forward to a more useful place, thereby reducing the amount of air required to move a heat front through the reservoir. Several approaches have been proposed. Merriam and Squires1 taught that a combustible (fuel) gas should be injected along with the air and water. This, however, would give at least a tendency toward reverse combustion instead of forward combustion, and would reduce the velocity of the heat bank, defeating the primary purpose of the water injection. Pelzer2 described primarily a batchwise method of forward combustion and water flooding. He advocated burning part way through a reservoir with forward combustion, then switching from air to water injection alone to push the heat toward the producing wells. Though possible, this method has serious disadvantages, the major one being that, by the time water injection is started, much of the heat has been irretrievably lost to the overlying and underlying formations. We have described what is considered a practical Combination Of Forward Combustion And Water-flooding (COFCAW).3,4 Air and water are injected simultaneously (or alternately) after a small heat bank has been formed by forward combustion. Some of the injected fluid fills up the region behind the heat bank; the rest enters the heat bank. Upon encountering heated rock, the water is converted into steam, which then flows ahead of the combustion zone and displaces much of the oil in place. Only enough air is injected to provide heat for vaporization of the water and to compensate for reservoir heat losses. Since the size of the heat bank is minimized, heat losses also are minimized. Because of more efficient oil displacement ahead of the combustion zone, fuel consumption is reduced. Too, unlike a forward combustion zone that cannot move until all fuel at a point has been consumed, COFCAW leaves some

Jan 1, 1970

By Dave J. Porter

Si bien, los proyectos son el camino para que una organización minera cumpla con su estrategia, la gran mayoría de su historial de cumplimientos son un fracaso puesto que el impacto del proyecto no es tan rico en sus etapas y las organizaciones mineras no pueden cumplir con su visión y estrategía. En ese sentido, el presente texto señala la importancia de una adecuada gestión de proyectos para que la organización minera cumpla con su estrategia. Así, la madurez de la gestión de proyectos es un indicador de éxito continuo y requiere de visión, compromiso en las etapas iniciales, ya que sus ganancias son difíciles de cuantificar.

Apr 1, 2012

By Tripathy A. K, Satapathy B. K, Nayak B, Mohanty J. N, Dey D. N

The paper deals with the metallographic tudy of heat treated chromite and chromite-coke composite briquettes. The briquettes, prepared from chromite concentrate of Orissa Mines using molasses-lime, dextrinelime and tamarind seed as binders, were subjected to different temperatures and examined metallographically. The change of phase with temperature was analysed by X-ray diffraction.

Jan 1, 1987

By D. Bitzios, A. Gracia, V. Meggiolaro, J. D. Baker

Synthesis report on a project carried out under the EC-funded BRITE-EURAM programme. A large deposit in Spain and several smaller ones in Greece and Sweden were investigated. Beneficiation testwork, including the development of an innovative wet circuit, was undertaken in Italy. The Spanish Ilustracion deposit lies occurs in thin, white layers throughout a zone 35-40 m thick and 1.5 km long, in laminated calcsilicates. Total resources of more than 100 000 000 t include proven open-pittable reserves of 4 500 000 t averaging 35% wollastonite. The beneficiated product is suitable for various applications, including ceramics. The Swedish and Greek marble-hosted skarn deposits include Albatross, with 2 500 000 t of reserves at 30% wollastonite, and Panorama, with reserves estimated at more than 700 000 t

Jun 21, 1905