Search Documents

By T. Haubold, K. Ortner, T. Jung, D. Roth-Fagaraseanu, C. Mattern

Application of integrally bladed disks (blisks) is of increasing interest in compressors of aero engines. Blisks are preferred due to their potential for size and weight reduction, for increased performance and for reduced manufacturing costs compared to conventionally bladed disks. Erosion of the blisk aerofoils in service reduces engine performance, and can result in short shop visit cycles. This significantly increases the life cycle cost of these components, particular when considering that eroded aerofoils can't be exchanged easily for blisks during refurbishment. Shop visit cycle times can be extended and maintenance costs can be reduced through the application of an effective protective coating. The ongoing development of an erosion resistant coating and deposition process suitable for coating complex blisk geometries is described here. The coating is a multilayered W /TiB2 system exhibiting superior erosion resistance compared to known single- and other multilayer concepts. A modified sputter process is used to enable coating even of blisk geometries with shadowed surface to competitive recurring cost.

Jan 1, 2006

By V. Estrada, G. Aguilera

"Since the most of mineral processing are wet, and for more specific applications where it is necessary to increase the purity through leaching and / or concentration, the proper dispersion is the first, and perhaps more crucial stage in the whole chain of processing. This specific process is based on the formation of a dispersion or suspension of mineral, trying to make the mixture as homogeneous as possible, and with specific rheological conditions. Sometimes it is not enough agitation to make it happen, so that chemical additives are used as an aid. However, the addition of chemicals strongly alters the viscosity and other rheological properties of the suspension factor to consider for subsequent steps to ore beneficiation. In other hand, in a process where no chemicals used often employ large quantities of water to achieve dispersion. But if an efficient chemical agent, which optimizes said dispersion through a specific physicochemical effect on the particle surface is used, also it can generate rheological advantages, besides achieving rational use of water and increase the recoveries of the product main about also optimal costs. The aim of this work is to find the optimal rheological conditions for a dispersion of kaolin as study case, looking for stability, best disaggregation, viscosity and pseudoplasticity.To find the optimal additive, the evaluation parameters were: 1) Best degree of dispersion of the suspensions according to the analysis of the flow curve; 2) Best level of disaggregation of particle chemical analysis delaminated by Particle Size Distribution; and 3) Best thixotropic rheological parameters and pseudoplasticity. Finally the optimum additive as one that meets the best combination of parameters is proposed.INTRODUCTIONKaolin is a clay material formed by altering of feldspar composed mainly for kaolinite. Depending on the application, the kaolin as raw material must be refined and processed because the ores of clays contain usually a lot of impurities derived of its sedimentary source, such as feldspar, mica and quartz (Torres, et. al., 2011). According to the experience on the plant floor and the publication of several scientific papers, it is known that the dispersion is a crucial stage in mineral processing (Greene, Duke, & Hunter, 1965) (Raghavan, et. al., 2004), not only because of the disaggregation of particles, besides because of the humectation of them. Is clear that disaggregation of particles give to the suspensions rheological stability, and the humectation improves the effect of further processes like grinding or chemical treatment. The dispersion process involves making a suspension of the mineral with a solvent which is usually water, to obtain a homogeneous dispersion, with the aid of energy of stirring. Sometimes is not enough the agitation (even with high energy) for this to occur, so is necessary the use of dispersing substances which introduce ions and molecules as modifiers of chemical potential, forcing the molecules of the material to disperse. Sometimes their use even could affect the pH of the suspension in a non-desirable condition. (Flores, 2013)."

Jan 1, 2016

By Fidelis T. Suorineni

The conditions for rockburst occurrence are traditionally identified as: high stress, high extraction ratio, strong brittle rocks, folding, faulting, and unfavourable excavation geometry. Based on a critical review of case histories, this paper identifies oblique loading of orebodies by the major far field principal stress as a cause of rockbursts. Orebodies subjected to this loading condition are termed orebodies in shear. Orebodies in shear are subjected to compressive and shear loads. The case histories presented unambiguously show that the magnitudes of the far field principal stress alone, and a knowledge of the conventional rockburst causing factors are not sufficient for mine planning and design. The orientation of the major far field principal stress, or for that matter the driving stress relative to the orebody axis, should be recognised as one of the causes of rockbursts. It is suggested that since stress orientation is an important factor, and orientations from stress measurements are so variable, orientations from stress measurement data be complemented with underground observations from borehole and excavation breakouts to determine the actual in situ stress orientation, whenever possible. Also stress modelling for the design of critical elements (pillars) should include a sensitivity analysis on the relative critical field stress direction. The paper emphasises that special attention should be paid to or

Jun 1, 2012

By T. Plikas, T. Porretta, M. Al-Dojayli, B. Pretorius, J. Woloshyn, H. Ghorbani

"Water-cooled ducts represent an integral part of high temperature off-gas systems in metallurgical processes. Typically, off-gas enters these ducts at significantly elevated temperatures; therefore, water cooling may be required to maintain the duct skin temperature within allowable design limits. These off-gases are typically of high mineral content that could lead to dust buildup, and there is a possibility of slag buildup / molten metal splashing. Therefore, dust cleaning provisions may be necessary in order to remove or minimize accretion on the duct wall, which could otherwise impact the water cooling and the system process efficiency. These ducts may have complex geometry and experience a wide range of loading, including gravity loads, water and gas pressures, cyclic thermal loading and dynamic impact forces. Consequently, the thermo-mechanical assessment of such water-cooled ducts is critical and requires consideration phenomena such as high temperature gradients, potential nucleate boiling, thermal ratcheting and fatigue failures. Such assessment is not comprehensively covered by design-by-rule design codes and guidelines due to its complexity. This paper presents a successful implementation example of design-by-analysis methodology to improve the design and extend the life of a water-cooled furnace transition duct using Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA).INTRODUCTION Water-cooling represents an important part of high temperature off-gas systems in metallurgical processes. Typical temperatures of the off-gas in the furnace uptake are in excess of 1400°C, and thus there is a need to maintain the water-cooled duct and jacket skin temperatures within their material allowable design limits. Water-cooled channels have been used effectively in arc furnace roof design (Sosonkin et al., 1972; Smolyarenko and Khainson, 1988) and other furnaces as well as in furnace fuming jackets (Scholey et al., 1994). The design of these systems was based on one-dimensional analysis to ensure sufficient cooling is available under extreme furnace conditions (Smolyarenko and Khainson, 1988; Scholey et al., 1994). With advancement in furnace and fuming system designs, water-cooled duct designs have become more complicated in geometry. Numerical techniques, such as three-dimensional fluid flow and heat transfer modeling, are therefore needed to more accurately calculate water velocity, temperature and convective heat transfer coefficients in the water-cooled channels (Haywood et al., 2002; Henning et al., 2010). This is of particular importance around geometric corners where stagnant water flow may lead to local nucleate boiling at the critical heat flux, causing hot spots (Bergman et al., 2011). High wall skin temperatures increase the risk of failures due to thermal stresses as well as increasing corrosion rates (Gelfi et al., 2012), leading to costly equipment downtime and potential safety risks."

Jan 1, 2017

By R. M. Berry

A brief outline of refining methods used to (1) upgrade yellowcake to nuclear purity and (2) convert the uranium to the chemical and physical forms required by the fuel fabricators is presented. The uranium hexafluoride (UF6) production facility now under construction at Eldorado, Port Hope, is discussed. Technological improvements in uranium refining are considered.

Jan 1, 1969

By G. W. H. Norman

INTEREST in the mineral possibilities (gold, copper) of northern Quebec, north of the Quebec-Cochrane branch of the Canadian National railway, has centred for many years in the Chibougamau district (see Figure 1). Since 1934, however, promising gold discoveries in the Rose Lake-Florence River section, 115 miles southwest of Chibougamau lake, have widened the interest, and prospectors have examined other parts of the country between Chibougamau lake and Bell river and the surrounding districts. The object of this paper is to !resent an outline of the geology, and to describe the mineral deposits, o part of this region, or, more specifically, of the part embraced by the Opawica-Chibougamau and Waswanipi map-areas(l), which include the districts about Chibougamau lake and Rose lake-Florence river, where mineral deposits are now in course of development either by surface or underground work. Early discoveries, developments, and explorations in the Chibougamau district are well summarized in the report of the Chibougamau Commission, published in 1911(2). The Commission discredited previous optimistic accounts of mineral discoveries in the area, made initially in 1903, but at the same time they expressed the opinion that, from a geological standpoint, the district promised a reward to diligent and intelligent prospecting. Their general conclusion-that prospecting in the area was not then (1911) commercially advisable in view of its inaccessibility and other handicaps shifted interest from the district until, some years later, valuable discoveries were made in the Rouyn area, and aircraft widened the field of successful exploration. During the past ten years or so, considerable energy has been spent in promoting the development of the district. The net result has been the discovery of a number of prospects, the majority of which have been explored only by trenching and, in most cases, diamond drilling.

Jan 1, 1936

By Christopher Boys

"Abstract -Many water inflows in Saskatchewan potash mines are linked to salt anomalies. Potash ore and three anomalies in the PCS Cory potash mine in the Patience Lake Member of the Prairie Evaporite Formation were studied to understand the processes involved in their formation. Another goal was to find geological indicators of the proximity of anomalies. A geological model that relates the potash to the salt anomalies has been developed.Up to five post-burial facies may be recognized . These range from carbonate-mud collapse breccias to bedded sylvinite, and probably result from post-burial leaching. ln this model, the same fluids that caused widespread recrystallization and possibly enrichment of the potash salts, started by dis­ solving huge cavities in the evaporites . The effects of the leaching were highly variable, indicated by selectively preserved delicate laminae and chevron textures, to deformed and totally dissolved salt beds . ln at least two major events, Late Devonian and Cretaceous, collapse structures may have acted as conduits for overlying formation waters to cause pervasive leaching and recrystallization of the Prairie Evaporite Formation .Geological indicators of the proximity of an anomaly may include: a change in Insoluble seam color from greenish-gray to mottled brown and greenish-gray, unusual local increases in ore grade, large patches (e.g., >200 cm2) of sylvite-poor potash crosscutting units near the top of the ore zone, and drops in topography >10 m of the marker seams. Anhydrite was more common in an anomaly than in ore. The local abundance of anhydrite in ore may indicate the proximity of some salt anomalies.Once an anomaly has been encountered, indicators of a major collapse feature may include: stretched clay seams, folded beds, small collapse features (1 m to 20 m), numerous washouts, or split clay seams with injected salt. Any number, or none, of these indicators may be found close to a major collapse feature."

Jan 1, 1993

By A. F. Gregory

"AbstractA resumé of aerial radiation survey studies performed by and for Eldorado Mining and Refining, Limited, since 1943 is presented. Flight tests were initiated in 1947 and were followed .by intensified use and study of Geiger counters and other radiation detectors. Development of an aerial scintillation counter began in 1948, but •a sensitive large crystal unit was not available for exploration purposes until 1950. Modifications of this unit have been used in all subsequent surveys.For the Eldorado detector, several limiting conditions were established for successful radioactivity detection, the most important being that natural vein exposures can only be assuredly detected .at distances less than 150 feet. Sedimentary and pegmatitic radioactive occurrences can be detected at much greater distances. A helicopter investigation technique appears to •have •a useful prospecting potential.IntroductionAerial radiation surveys were first proposed in the early 1940's. However, it was not until 1949 that airborne detectors were extensively used in the search for radioactive minerals. Eldorado has flown about 50,000 miles of exploration flights, exclusive of tests, using a variety of •detectors and aircraft. Considerable data have •been gathered for .the evaluation of the several techniques employed. Much of the early work was performed with the co-operation of the National Research Council of Canada ( 1). More recent work was done in conjunction with the Commercial Products Division of Atomic Energy of Canada, Limited. The Development Department of this latter corporation designed and built the scintillation counter used in recent Eldorado surveys."

Jan 1, 1955

By M. Epiney, A. Ghahreman, R. Kim1and

"In the presence of sulfidic refractory ores, increasing the dissolved oxygen (DO) concentration can positively affect the gold leaching rate. To identify the role of DO in gold cyanidation, electrochemical behavior was studied in the presence of 3 different ores. Sample 1 was a low sulfide pyrite ore, contained 5.14% pyrite, 0.19% galena and 3.09% S. Sample 2 was a pyriticore as well, contained more sulfide as 8.35% S, and 12.4% of pyrite. Sample 3 was a tailing of silicate gold ore, still containing75 g/tAu, 0.13% Pb and 0.18% S. Gold cyanidation kinetics were studied by cyclic voltammetry (CV) and chronoamperometry tests. With sample 1, the gold oxidation peak current density from CV curve was increased to 1.38mA/cm2under oxygen injection, while it was only 0.66 mA/cm2with air injection. From chronoamperometry test, the reaction rate was also faster under oxygen injection. Sample 2 showed similar behavior with sample 1, but the gold oxidation peaks higher than sample 1, i.e. 1.75 and 2.27 mA/cm2, under air and oxygen injection, respectively. However, it seemed that the gold oxidation was impeded by sulfide ions for a longer period. In the presence of sample 3, the gold oxidation peak was the highest among three ores –2.75mA/cm2under oxygen injection, because of its lowest sulfide content. However, from chronoamperometry test, it was also shown that the gold oxidation was impeded because of a significant amount of Pb in the ore sample.INTRODUCTIONIt is well known that gold is leached under oxidative condition (Marsden &House, 2006). Through the most representative and oldest gold leaching technique, cyanidation, more than 90% of gold can be selectively leached from an ore. According to Elsner’s equation, gold is leached in cyanide solution by forming cyanide complex [Au (CN)2–], and oxygen is consumed as an oxidant(Eq. 1)."

Jan 1, 2017

By N. K. Jaber

The "Pidgeon Process" for the extraction of magnesium from dolomite ore utilizing ferrosilicon as the reducing agent has been studied extensively by active metallurgists such Mr L,M, Pidgeon the father of this process, Most of the work sited so far has focused on heating the (FeSi/MgO,CaO) briquette mix under vacuum in stainless steel retorts by external fuel hydrocarbon heating, In this work Electrical Induction Heating was employed as the heating method whereby the briquette mix was placed in a steel crucible around which an Induction Heating copper coil was wound and placed inside in a stainless steel vacuum tank, It was observed that by virtue of the fast Induction Heating method utilized in the silicothermic extraction process higher reduction temperatures were reached in shorter periods of time due to fast heat transport into the ore charge mix, This facilitated shorter metal reduction times as compared to the conventional fuel heating methods.

Jan 1, 2006

By G. E. Veins

This paper summarizes an investigation in which beneficiated ilmenite ore was smelted in a continuous, three-phase, 250 kv.a., open-top electric furnace. Minus %. inch ore was smelted, using the standard method. Fine ore, in the order of minus 14 mesh, was smelted in the briquetted form by the open bath method, and in the unagglomerated form by the cold dry-top method. The latter was shown to be superior. The data obtained .are discussed at some length. During the investigation, slag aver-aging 82.5 per cent Ti02 was produced over a period of 87 hours, the maximum being 85 per cent. Such slag should .be particularly attractive for the production of titanium tetrachloride, from which titaniurn metal is produced. The advantages of using paper-mill bark for producing a furnace charge of low bulk density, as required in cold dry-top smelting, were emphasized.

Jan 1, 1957

By N. Erarslan, M. Ghamgosar

The size of rock fragments depends on the nature of the loading applied the strength of the minerals and the texture of the rock. Research in the literature demonstrates that there is a distinct difference in the rock fracturing process for static and cyclic loading. The tensile strength of brittle rocks is also one of the most significant parameters influencing the rock fracturing process and the propagation of micro-fractures on the crushing, blasting and cutting of rock. The Brazilian indirect tensile test, one of the methods approved by the International Society for Rock Mechanics (ISRM), has been used to determine rock fracture behaviour under different cyclic loading modes. In this study, the dimensions of Brisbane Tuff specimens have been selected according to the method outlined by the ISRM. The main aim of this study is to evaluate the effect of cyclic loading amplitude and frequency on the Fracture Process Zone (FPZ) at the micro-, meso- and macro-scales. The post-failure behaviour of the Brisbane Tuff specimens was obtained under cyclic loading with frequencies varied from 1 to 10 Hz. The amplitude was varied from 10% of Ultimate Tensile Strength (UTS) up to 80% UTS. Laboratory investigations of rock fragment size revealed that different loading frequencies and amplitudes produce different FPZ dimensions. Multivariate Analysis of Variance (MANOVA) results demonstrated that the FPZ dimension is relatively sensitive to the frequency change. Fragment size analysis showed that the FPZ is a consequence of the initiation, propagation and coalescence of micro-fractures and depends on the nature of the loading. Laboratory evidence showed that the FPZ dimension, for the cyclic tests performed on Brisbane tuff, is ranged from 0.07 to 20 mm. The achievement of this study highlights a key finding in the understanding of fracture patterns and propagation models in the FPZ under cyclic loading, which is the dominate mechanical action in the oscillator disc cutter (ODC).

Jan 1, 2015

By K. Iturralde

The article discusses the possibility of automation in refurbishment processes of social dwelling built from 1950 to 1970. These massively produced buildings were mostly designed prior to the law enforcement regarding thermal insulation or accessibility. Nowadays, many of these buildings are being retrofitted. The article focuses on the works in the external envelope. The task of renewing the whole social building stock is big and it requires a systematic process that facilitates a rapid upgrading, without neglecting the specific situation of each case. How could an automatic refurbishment process of these buildings be defined? The process should start with the data collection of the building and the creation of a 3D model using software such as BIM. The project, drafted in 3D, should facilitate the manufacture of building elements by robotics. In turn, it should be noted that during the assembly at the site, the pieces must be fixed quickly and efficiently. Is it possible to implement an automated process for the refurbishment of apartments built in the second half of the twentieth century? To approach the answer, a virtual refurbishment project is performed. The article focuses on the rehabilitation of the building envelope. Furthermore, it gives special attention to the double skin facade. It is well known that a second skin in this type of building can be an element that integrates several functions. Finally, needless to say that refurbishment of residential buildings is a need in our society. By extending its life cycle, robotic refurbishment provides more favorable socioeconomic and environmental capabilities than the sole construction of new buildings.

Aug 1, 2013

By M. R. P. Snow

"This paper outlines geotechnical conditions that commonly exist in underground, hardrock mines and the challenges posed for ground-support steel, specifically rockbolts, used in these environments. A model is proposed whereby the in-situ stress and rock-mass classifications (based on Bieniawski’s rock mass rating) form the basis of determining the desired steel properties of the rockbolts used. Based on the ASTM F432 bolting specification, recommended minimum steel properties are defined for three ranges of in-situ stress levels, each with their own six ranges of RMR values. Heat treatment for the steel can be specified once these minimum steel properties are known.RÉSUMÉ Le présent article décrit les conditions géotechniques qui existent fréquemment dans les mines souterraines de roches dures et les défis que cela pose pour le soutien de terrain en acier, plus spécifiquement les boulons d’ancrage utilisés dans ces environnements. Un modèle est proposé dans lequel les contraintes in situ et les classifications de la masse rocheuse (selon la classification de la masse rocheuse de Bieniawski) servent de base pour la détermination des propriétés désirées pour l’acier des boulons d’ancrage utilisés. En se basant sur les spécifications de boulonnage de l’ASTM F432, les propriétés minimales recommandées pour l’acier sont définies pour trois plages de niveaux de contraintes in situ, chacune avec sa propre plage de six valeurs de classification de la masse rocheuse (RMR). Un traitement thermique pour l’acier peut être spécifié une fois que ces propriétés minimales pour l’acier sont connues."

Jan 1, 2016

By G H. Reavely, The University of Western Ontario Department of Geology

The lower Middle Devonian Sylvania Sandstone occurs in the sub-surface in the western part of Mal-den township, Essex county, Ontario. The formation is composed of well rounded, frosted quartz grains with a silica content varying from 42 to 93 per cent and the grains are cemented by carbonate, constituting up to 57 per cent of the rock. This sand-stone is not a homogeneous bed but is divided by strata rich in carbon-ate cement. The thickness of the Sylvania in Malden township varies up to a known maximum thickness of 88 feet. The lower contact with the chert-bearing Bois Blanc formation is sharp but the upper contact with the Amherstburg formation (Detroit River group) exists as a transition by a gradual downward increase in quartz grains. The Sylvania would seem to outcrop in the lake bottom near the mouth of the Detroit River dipping to the north along a broad anticline the axis of which follows the Detroit River. Just south of Amherstburg, a local east-west trending

Jan 1, 1961

By E. J. Wasp, T. L. Thompson, T. C. Aude

The paper will deal with some of the more important technical aspects of slurry pipelines as they apply to the mineral field. In addition, the use of these technical concepts in arriving at realistic economic figures will be discussed.

Jan 1, 1970

By L. A. Homeniuk, R. Bonnar

"The Athabasca Basin has been the scene of an intense exploration effort since the late 1960s, resulting in the establishment of this area as one of the major uranium districts in the world.The A thabasca Group is of Helikian age and unconformably overlies metamorphic rocks of Aphebian and Archean age. Most of the known uranium deposits have a close spatial relationship with the unconformity, graphitic meta-sediments, major northeast-trending structures and the basin edge. It should be noted that, in regard to the latter, some of the Cluff Lake deposits are exceptions.The pre-Helikian rocks underlying the Athabasca Group have been divided into six Iithostructural domains. The known uranium deposits are concentrated in the Wollaston and Mudjatik domains in the southeastern portion of the basin.The orebodies typically have a narrow high-grade portion below the unconformity and a broader, lower-grade disseminated zone in the overlying sandstone. Over-all grades average over 1% U3O8 and our estimate of known reserves totals more than 400 million pounds of contained U3O8. Some of the deposits have high concentrations of other metals, including nickel, arsenic, cobalt and gold. Ubiquitous chlorite and clay alteration is characteristic of the orebodies.Other Proterozoic basins in Canada of similar ages and having analogous geological settings to the Athabasca have received far less attention. Although little of the known uranium mineralization in these basins is related to the Helikian unconformity, there may be an exploration potential for deposits similar to those of the Athabasca basin.IntroductionThe Athabasca sedimentary basin is located within the Churchill Structural Province of the Canadian Shield in Northern Saskatchewan. The basin is elliptically shaped and is approximately 800,000 square kilometres in area.The objective of this paper is to summarize the various elements in the genesis of the unconformity-type uranium deposits of the Athabasca Basin and to evaluate the comparative potential of other Proterozoic basins to host similar unconformity-type deposits."

Jan 1, 1982

By G. Gu, B. Fang, R. W. Revie, M. Elboujdaini

Electrochemical behavior of an X-80 pipeline steel, including frequency-sweep electrochemical-impedance spectroscopy (EIS), time-sweep EIS at a constant frequency and open-circuit potential (OCP) monitor, was investigated using four-point bending specimens subjected to a stress-corrosion cracking (SCC) test in a near-neutral pH environment. The capacitive loop became smaller with test duration, revealing an increase in the corrosion rate. The resistance obtained in the constant-frequency EIS test showed two regions, of which the region with a remarkable decrease in resistance transformed into a region of slow decrease, whereas the capacitance increased with test time indicating that iron dissolution was fast at first, and then a corrosion product or film formed and covered the surface, leading to the pitting formation.

Jan 1, 2005

By V. Prasad, A. Afacan, K. Popli, S. Dubljevic

Froth flotation is one of the most common and widely used separation processes in the mineral processing industry; however, its complexity means that complete understanding of the process has not yet been achieved. A dynamic fundamental model is needed to enhance the understanding of the process and to improve process control. It is challenging to capture all the phenomena involved; hence, we propose a multiscale modeling approach with a framework ranging from macroscopic (equipment scale) to microscopic (attachment, detachment) models along with distribution models for ore particle sizes. Real-time froth properties are obtained using a vision-based sensing system. These measurements can be used for developing a soft sensor for grade using statistical methods such as PCR (principal component regression) and PLS (partial least squares) regression. The fundamental model is updated in real-time using extended Kalman filtering. Attachment dynamics are studied for different particle size distributions. The modeling and soft sensing is tested on batch flotation cell for the pure mineral galena with different particle size distributions using Xanthate and MIBC as collector and frother, respectively. The model, online measurements and soft sensor are useful in developing monitoring methods for froth flotation.

Jan 1, 2015

By D. Y. Kim

This paper shows an approach that a gondola-typed robot recognizes walls on building facades. It is applicable for autonomous or teleoperated building façade painting robots. The robot may react based on the wall classification data. This approach is based on 2D LRF(two-dimensional Laser Range Finder). The robot acquires relative distances to walls, and a Kalman filter decides correspondence of walls. An ARS(Attribute Reference System) sensor helps convert LRF coordinate to global coordinate. The experimental results demonstrate the conversion of LRF data.

Aug 1, 2013