Search Documents

By J. Suarez

The innovation initiatives for world-class mines today and in the future focus on automation and robotics in equipment and machinery. These innovations have benefited from the development of advanced tools in global positioning, the Internet, the capabilities of data storage, transmission and handling, and intelligent systems. Forward-thinking companies have been investing in automated trains and trucks, selfdrilling rigs, intelligent flotation systems, etc. Considering that the emphasis has been mostly laid on improving the performance and reliability of the equipment and machinery, it is not surprising that the visibility was geared toward mechanical, electrical, process, and metallurgical engineering. One of the critical disciplines, mining engineering, has had less shine from the spotlight of automation and robotics. Mining engineering is concerned with the design, the operation, the management, and the reclamation of mines and mining facilities. In essence, it does benefit from the advantages of automation and robotics in equipment and machinery. However, being ?left out? in the innovation process may impede the core capabilities of this engineering discipline, which would create a two-tier knowledge and technology system in mines. For example, shovels in an open pit may be equipped with technology that can send real-time data of actual payload, number of buckets, mechanical status, etc. But, are mining engineers aware of the possibility to incorporate the data into their planning tools in order to have updated forecasts and accurate information? And if they are, are they equipped with the tools to reap the rewards of those technologies? And if so, is the personnel trained to use the tools efficiently? This paper is a contribution to the discussion on the technological advances in mining engineering. For the authors, the roadmap to the future requires a smart integration of technological advances in hardware and software so that mining engineers are not only aware of the possibilities, but also trained and capable of using the available tools. Essentially, this paper believes that automation and robotics in equipment alone will be undervalued and underutilized if the owners and drivers of the mining systems (i.e. the mining engineers) do not possess the tools and training to integrate the technological advances into the functions of mining engineering. The intent of the paper is to analyze the available technologies for the core mining engineering functions of design, planning, scheduling and optimization. The analysis will lead to discussions and suggested solutions on integrative technology solutions that would create optimum value for the mining processes and equipment technologies.

Aug 1, 2013

By C. H. B. Leitch, T. N. MacAuley, R. L. Linnen, A. E. Williams-Jones

"The Trout Lake stockwork molybdenum deposit is temporally and spatially related to the emplacement of a late Cretaceous granodiorite-tonalite stock in southeastern British Columbia and contains an estimated 49 million tonnes grading O.I9% MoS2- No metal zonation patterns are apparent, with the exception of peripheral tungsten skarn, and exploration was guided largely by geological interpretation. It is typical of the granodiorite, or fluorine-poor type of molybdenum deposit. Molybdenite is contained within a quartz-feldspar vein stockwork and coeval dissemination in igneous (and less commonly metasedimentary) hosts. In general, molybdenite is strongly associated with alkali feldspars, but in detail it is intimately associated with incipient muscovite replacement of albite and K-feldspar; veins that lack feldspars are also typically barren of molybdenite. These textures suggest that fe/dspathic alteration (and precipitation in veins) was an important precursor to mineralization, and the occurrence of similar textures elsewhere (e.g. Henderson) suggest that early feldspathic alteration is important to the genesis of molybdenum deposits in general. Molybdenite deposition at Trout Lake was preceded by contact metamorphism, skarn and potassic alteration, and was overprinted by muscovite-ankerite (phyllic) alteration. Only moderate temperature changes are recorded by the metamorphic and alteration mineral assemblages (350°C to 450°C}; however, with time, fluids became increasingly more acidic and enriched in C02- In light of the intimate molybdenitemuscovite intergrowths, the decrease of pH probably exerted a major control on mineralization.IntroductionGranite-hosted molybdenum deposits can be classified in terms of the composition of the related intrusion, e.g., the granodiorite and granite types of Mutschler et a!. (1981), or the calc-alkaline, alkali-calcic, and alkalic types of Westra and Keith (1981). They have also been classified on the basis of their fluorine contents (Theodore and Menzie, 1984) with the fluorine-rich and -poor varieties roughly corresponding to granite- and granodiorite-type deposits, respectively. For economic reasons, most exploration and research has concentrated on the high-grade/large tonnage granite-type of deposit, exemplified by Climax. F1uorine-poor, granodiorite-type deposits are, however, the most common type in Canada and have been mined in the past (e.g., Endako). In this paper, the authors summarize the research that has been carried out on the fluorinepoor Trout Lake deposit (Boyle and Leitch, 1983; Linnen, 1985; Linnen and Williams-Jones, 1987; 1990) and use what has been learned to develop guidelines for the future exploration of fluorinepoor, granodiorite-type molybdenum deposits."

Jan 1, 1995

"The Cordillera contains numerous porphyry deposits and prospects, many containing economic quantities of copper, molybdenum, gold and tungsten. Over the lost twenty years, different phases of exploration have been driven by individual commodity prices and new discoveries. Exploration methods have remained largely unchanged since the 1960s and 1970s with the range of techniques chosen for each situation depending on the stage of the program, the type of porphyry target and the local environment. Improvements or changes to techniques have resulted from awareness of specific features in new deposits or regional problems. During the last ten years much of the emphasis has been on the re-evaluation of known porphyry deposits with more exploration in areas previously recognized as prospective. Re-evaluation of known deposits has resulted in increased reserves, often with improved gold grade, and the discovery of new zones. Several new deposits have been discovered including gold-only deposits of probable porphyry affinity.Research related to porphyry deposits has followed trends in exploration and has been directed toward the type of deposits that have been of current interest. In addition to research on specific deposits and areas, general research related to porphyry deposits has addressed three broad themes. The first theme involves the role of tectonic processes and the nature of source regions. Although different in detail, recent tectonic models suggest that a tectonic change or hiatus may be important for the generation of metal-rich magmas from various source regions and subsequent fractionation that permits volatile saturation. The second theme is based on magmatic processes, particularly the generation of a volatile phase enriched in metals. This research supports the general orthomagmatic model for porphyry deposits and has helped to define the influence of specific variables in the generation of different types of porphyry deposits. Finally, research on alteration and mineralization has provided evidence for different types of fluids and fluid processes involved in the formation of porphyry deposits. These data also support the orthomagmatic model but indicate additional complexity in magmatic-hydrothermal systems including the role of external fluids. Although important advances have been made, research has had a limited impact on exploration.Exploration and research on deposits that occur in the peripheral and upper parts of porphyry systems have been important over the last ten years. Although considerable advances have been made, the relationship of different styles of peripheral mineralization to magmatic processes in the core of the system remains ambiguous. An improved understanding of the processes that generate zoning, peripheral mineralization, and the surrounding alteration envelopes would be beneficial to exploration."

Jan 1, 1995

By A. Saigal

A finite element analysis based investigation using DEFORM software was undertaken to model the extrusion of 15% alumina and 15% silicon carbide reinforced aluminum metal matrix composites. The study dealt with predicting the extrusion load as a function of ram displacement and initial billet temperature. The finite element simulation was also used to determine the maximum extrusion load, temperature distribution, maximum temperature, strain rate, velocity and stress distributions in the billet during the hot extrusion process. The constitutive equation used was of the type: Z = E exp(Q RT) = A{sinh(ao-)}" where Z is the Zener-Hollman parameter (temperature compensated strain rate), s is the strain rate, Q is the activation energy, R is the gas constant, T is the absolute temperature, a is the flow stress and A, a and n are constants. Based on the work of Davies et al and McQueen and Konopleva, the values of Q (KJ/mol), a (MPa-1), n and A for aluminum 6061 composites reinforced with 15% alumina and 15% silicon carbide used are 181, 0.024, 4.15 and 1.33x10'2 and 233, 0.052, 2.60 and 1.26xl0'4, respectively. Even though the individual parameters are quite different, it was found that the predicted maximum extrusion load, temperature distribution, maximum temperature, strain rate, velocity and stress distributions are quite similar and differ by no more than 1-2 percent between the two composites indicating that the deformation behavior is primarily controlled by the matrix material and is not a function of the type of reinforcing ceramic particulates.

Jan 1, 2004

By A. Ignatow

"A review is made of some of the principal factors and conditions that are, and will be, important to the over-all market climate for asbestos fibre and for the future of Canada's asbestos industry: - health hazard associated with asbestos exposure;- uncertain international regulatory environment for continued asbestos use;- adverse public reaction to asbestos;- product liability/litigation costs (U.S.A. primarily);- promotion of substitution by governments and asbestos user industries; and- minimal product and market development efforts by asbestos producing and consuming industries.In addition, Canadian producers, who export some 95 per cent of their production, face additional constraints:- dramatically reduced integration with asbestos-consuming industries;- 60 per cent of exports to most rapidly declining markets (U.S.A., Europe);- increased competition from offshore producers favourably located to growth markets in developing countries;- increasing production costs;- a strong dollar;- disadvantageous freight rates; and- loss of price leadership and price erosion.Future market trends, as well as prospects for Canada's asbestos industry, will be projected in this paper.Economic FactorsTable 1 presents asbestos fibre production in all countries for the period 1980-82. In certain instances, e.g. U.S.S.R. and China, these are capacity estimates as production statistics are not officially published. The U.S.S.R, by far, is the world's largest producer accounting for some 50 per cent of world production, though most production is consumed internally or by COMECON countries. It is estimated that some 700 plants produce asbestos-containing products within the U.S.S.R.Canada accounts for some 25 per cent of world production though it ranks first in world trade. Other important producers are South Africa Zimbabwe, Brazil and Italy. Since 1979, Canada's asbestos mining industry has experienced a dramatic drop in production and exports of asbestos fibre, as demonstrated in Table 2."

Jan 1, 1985

By R. G. Hamm

A brief outline covering the shovels and draglines in use in the open-pit mines of Western Canada, including British Columbia, Alberta and the Yukon, is given, followed by the procedure for the selection of the correct wire rope for each application. Such fa ctors as wire rope constructions, lay directions and types of cores are mentioned. Once the correct wire rope has been selected, there are variousfactors that can affect the service fife ofthe rope and the reduction ofdown-time during rope change-overs. Factors such as hairpin winding, types of Becket loops, and shovel drum and bail adaptors are described.

Jan 1, 1979

By M. B. Dusseault, A. Pirayehgar

"There is concern that hydraulic fracturing (HF) near an existing critically stressed fault could trigger slip and generate a seismic event of significance. To this end, a mathematical discontinuum model representing a naturally fractured rock (NFR) mass containing a fault is created, and fault slip response to fluid injection is studied. UDECTM is used as a Discrete Element Method (DEM) approach to define the seismic moment, and also to assess the influence of injection and slip on further shear slip propagation. In most of the simulations, slip and dilation take place along a number of oriented fracture surfaces, so it is reasonable to assume that in a real case, microseimic emissions would accompany each slip “event”. The moment magnitude scale (Mw) is used to measure the size of the microseismic event in terms of the energy released. Seismic moment is a measure of the total energy (work) released during a seismic event and is used to measure its size. From another aspect, the injection energy is calculated as the total energy required for achieving the hydraulic fracturing; this is viewed as energy to open fractures against the ambient stress field and much of it is potential stored energy that can be released and create discontinuities (work of fracture), deformations (W=F·d), heat and radiated seismic energy. A small amount of the total released energy is transformed to radiated seismic energy and another small amount results in tensile fractures. Fracture energy is used to calculate the work required to create fracture surfaces. Comparing the energy release by fracturing or seismic events indicates their contribution to the total amount of released energy or total work. The amount of energy associated with the stick-slip event is small compared with the overall work done to generate the distortions (i.e. increases in aperture by forcing them open) in the rock mass, and much of the energy in slip is lost as heat from the plastic deformation, rather than as radiated seismic energy.Microseismic monitoring shows the spatial distribution and magnitude of seismicity associated with slip of bedding planes and natural and incipient fractures. Work calculations have been undertaken to look at the various sources of energy storage (elastic strain energy) or dissipation (slip), and likely the energy losses from viscous dissipation could be addressed as well, helping to clarify HF processes in NFRs."

Jan 1, 2015

The uphole bench extraction strategy at EKJV Management Pty Ltd?s Raleigh Mine, requires simultaneous horizontal and vertical exposure of paste filled stopes. In order to prevent excessive ore dilution, the paste fill must be of sufficient strength to prevent failure during exposure. A numerical modelling methodology has been developed to accurately simulate the initial stress distribution within paste filled stopes, together with the strain-softening loading response of paste fill material. Due to the narrow orebody width and high deformation behaviour of the host rock mass, high closure strains are likely to cause a stiff, brittle fill material to undergo crushing failure upon exposure. The stability of paste fill exposures at the Raleigh Mine was determined by conducting a series of three-dimensional numerical models that incorporate the extraction, filling and exposure sequence of paste filled stopes. Stability charts for 2.5 m and 3.5 m wide simultaneous horizontal and vertical exposures have been derived based upon the numerical modelling results. Implementation of the stability charts has proved successful in limiting the amount of ore dilution from paste fill and provides a basis to optimize paste fill cementation and stability throughout the life of the mine.

May 1, 2007

By B. J. Cunliffe

"Filter cloth in the mining industry is an ambiguous title asthis suggests filter cloth use from underground ventilation to the refining processes. The time allowed for this paper would be better served in con-centrating on vacuum filters common to all mine mills and to offer some simple guide lines to the mill metallurgists in the choice of filter cloth for this type of filter.The requirement of the filter cloth is to separate solids from liquids under a vacuum head by forming a permeable layer of solids or cake, through which liquids can flow until the panel or disc sector leave the slurry tank and to continue to pass residual moisture from the cake formed during the cake drying cycle, and to discharge the cake on air-blow so that the cycle can be repeated.Whilst the mill metallurgist should not be expected to under¬stand all aspects of filter cloth manufacturer, it is however, advantageous for him to understand a little of the textile language associated with filter cloth for his own protection against ""trial-and-error"" methods, which are both time consuming and costly.If improvements are to be made over existing filter cloth in use an examination of the limiting factors of the cloth used should be made and the major causes for removal determined, e.g. cloth blinding, high moisture in cake, poor cake discharge on air blow, mechanical damage to cloth.As each of the limiting factors mentioned has a bearing on the choice of fibre used, the yarn type and weave of a suitable cloth, an under-standing of these points will assist the mill metallurgist in avoiding repetitive trials offering little degree of success."

Jan 1, 1971

By Michel Aubertin

Mining activities can produce large volumes of waste rock, which are typically deposited in piles on the soil surface, above the water table. Such piles can cover areas of several tens of hectares and can reach over a hundred meters in height. For hard rock mines, the waste rock grain size can vary from silty particles to metre-scale blocks. The internal structure of a pile constructed on a relatively flat surface typically includes two main zones. The first zone corresponds to the heart of the pile, and is formed by several sub-horizontal stratifications (with dense and loose layers) due to the heavy mine equipment traffic which induces local compaction and degradation of the waste rock. The second zone corresponds to regions where waste rocks are deposited by push-dumping or end-dumping close to the external flank of the pile, inducing grain size segregation along the slope. Depending on the deposition sequence, grain size distribution and bench height, a gradation may then be observed, with coarser particles (with cobbles and blocks) near the base and finer particles near the crest, together with inclined stratifications due to the advance of the deposition face. These internal features affect the distribution and flow of water (and air) in the pile. To assess the internal distribution of material properties within the pile, a combination of several tools is usually required which can provide information on the hydrogeological and geochemical characteristics of the waste rock. In this regard, geophysical tools are very interesting because they can lead to a threedimensional mapping of property variations. The information gathered from a combination of appropriately selected techniques can be used to construct numerical models to further study unsaturated water flow and reactive transport. Such simulations help better understand the pile response in its actual and future states, which in turn provides input to adjust the deposition sequence, to plan for closure, and to select an in situ groundwater monitoring strategy. The presentation will give an overview of techniques that have been developed to characterise material properties in the laboratory and in the field, and to obtain a general picture of a pile?s internal structure. Additional results on unsaturated reactive transport modelling will also be shown to illustrate how the internal pile structure may influence its hydro-geochemical and environmental response.

Nov 1, 2008

By Dani J. Alldrick, Alastair J. Sinclair, Colin I. Godwin

"The Stewart mining camp has a long history of precious and base metal mining. The camp is abundantly mineralized, with more than 200 widespread, varied, vein prospects, deposits and orebodies. These show wide variations in the mineralogy of ore, gangue and alteration assemblages, and wide variations in textures and structural settings. This report establishes the timing of the different metallogenic epochs and suggests a specific exploration application for systematic leadisotope analyses.Galena lead isotope ratios from a range of mineral occurrences indicate that all these varied deposits formed during two main mineralizing events. Lead isotope data from the Stewart mining camp do not provide absolute ages for the formation of mineral deposits, but the relative distributions of data are consistent with dates determined in other studies. One ore-forming episode occurred in the Early Jurassic and the other in the Middle Eocene. Both metallogenic epochs were brief, regional-scale phenomena. Some deposits from the younger mineralizing episode were emplacedadjacent to or superimposed on the older deposits.Field and laboratory studies show that the two metallogenic epochs are characterized by different base and precious metal suites: Early Jurassic gold-silver-zinc-lead-copper; and Middle Eocene silver-lead-zinc. Therefore, showings of different ages have different base and precious metal potentials and deserve different exploration emphasis. Lead isotope studies provide a reliable, cost-effective method for evaluating the age and commodity potential of small or recently discovered mineral showings and for setting exploration priorities on properties with several varied mineral occurrences. The determination of the age and metal potential of a prospect at an early stage of exploration may govern the urgency, intensity or even the necessity for further exploration work."

Jan 1, 1993

By F. Sheykh-Jaberi, S. L. Cockcroft, A. B. Phillion

A coupled fluid/structure model has been developed to simulate semi-solid deformation in an industrial aluminum casting alloy, A356. Although this alloy has a significant eutectic fraction, nearly 50%, it still shows susceptibility to hot tearing. The model geometry consists of solid grains, created from a Voronoi tessellation of the domain, surrounded by liquid. The simulation is performed using the commercial codes, Abaqus Standard and Abaqus CFD. The solid model calculates the velocity, stresses and distortions in response to an applied uniaxial strain, and transmits them to the fluid-flow model, which computes the velocity and pressure fields in the liquid. It was shown that grain size and configuration, fraction solid and fluid properties all affect the semi-solid deformation behaviour.

Jan 1, 2014

By Claude Hubert, Alex C. Brown, Pascal Marquis, D. M. Rigg

"Numerous studies of the Bousquet mining district, Abitibi, Quebec, mainly following the successive discoveries of new gold deposits over the past two decades, have led to a broad range of genetic hypotheses for their gold deposition. A compilation of petrographic, structural, and geochemical data indicates that the gold deposits are composed chiefly of pyritic schists derived from felsic and mafic volcanic and volcaniclastic protoliths, and of auriferous massive pyrite hosted by pyritic schists of felsic affinity. The deposits are typically located within zones of local pyrite enrichment and advanced-argillic alteration which are in turn enclosed within much larger zones of disseminated pyrite included in regional-scale, commonly anastomosing, zones of sericitic alteration.Overprinting relationships between three sets of folds and foliations indicate that the host-rocks of the gold deposits have retained the imprint of three successive generations of ductile deformation resulting from regional dynamothermal metamorphism. Sericitic and advanced-argillic alteration, together with massive sulphide deposition, are interpreted to have taken place prior to the onset of the ductile deformation, based on observations 1) of altered fragments of wallrocks which are enclosed within massive sulphide bodies and were thus preserved through regional metamorphism, 2) of the syntectonic deformed pyrite, and3) of the syn-tectonic porphyroblasts of andalusite, garnet and plagioclase. The orebodies are oblate to prolate, and the pyrite-gold mineralization is typically vein-type, distributed in foliation-oblique and foliation-parallel veins. The gold-bearing structures postdate all foliations, and are associated with retrograde alteration assemblages that are pseudomorphic after pea~-metamorphic porphyroblasts in host-rocks, and with cataclasticfabrics that overprint syn-metamorphic pressure-solution features and annealing fabrics in pyrite.Retrograde gold-bearing assemblages indicate a chemical disequilibrium between the ore-forming fluids and their host rocks. This disequilibrium rules out the possibility that gold was remobilized from its own host, and suggests, instead, that the ore-forming fluids and their metal contents had an allochtonous source. Stable and radiogenic isotope analyses indicate that the fluids had a metamorphic origin, and that the associated alteration took place after the culmination of the Kenoran orogeny."

Jan 1, 1990

By O. A. Ojo, D. L. Chen, N. Zhou, J. Q. Zhang, A. K. Khan

Dual phase (DP) steels are designed to consist of hard martensite dispersed in a relatively soft ferrite matrix, which offers a favorable combination of high strength with good deformability. Fiber laser welding (FLW) is becoming increasingly important for joining advanced materials due to its flexibility and deep penetration. In this study, the microstructure of a dual phase steel, DP980, welded by FLW technique was carefully analysed. Gleeble thermo-mechanical simulation coupled with analytical transmission electron microscopy (TEM) revealed that the FLW process produced significant microstructural changes in a narrow heat affected zone (HAZ) and fusion zone (FZ), which can result in dramatic changes in mechanical properties. This is reflected in the micro-hardness profile obtained across the welded material. The salient phase transitions induced by the FLW, including the formation of new martensite grains in the upper-critical HAZ and FZ, are discussed.

Jan 1, 2014

By K. A. Clark

A meeting between representatives of the Scientific and Industrial Research Council of Alberta and the Deputy Minister of Mines for Canada was held at Edmonton in May, 1929, for the purpose of formulating a co-operative plan for carrying forward studies in aid of the development of commercial methods for utilizing the bituminous sands of Alberta. It was agreed that to the Alberta Research Council should be allocated the general problem of investigation of the processes for the separating of bitumen from the sands, including studies of methods of emulsifying, dehydrating and otherwise preparing separated bitumen for industrial applications. It was further agreed that during the present year the work of the Alberta Research Council should be to continue its laboratory investigations of points of design of its separation plant; to further perfect its separation procedure; to recondition its existing separation plant at Dunvegan Yards, Edmonton, in the light of laboratory studies and to operate it for the purpose of demonstrating its efficiency; to carry on tests in emulsifying and dehydrating or otherwise preparing separated bitumen for industrial application; and on the basis of the experience gained in the operation of the preliminary plant at Dunvegan Yards to prepare and design and, as far as possible, to proceed with the erection of, a semi-commercial separation plant at a site to be chosen, probably at the bituminous sand deposits near McMurray, Alberta. This paper presents, in the main, a progress report of the carrying out of this programme.

Jan 1, 1929

By Keith Spence

"The notion of ""value"" has always been a subjective and contentious issue. Indeed, Value is in the eye of the beholder. There are varied methods and practices for valuing property, as there are industries in which they are applied. For example, there are ""replacement value"", ""insurance value, ""salvage value"", ""appraised value"", ""book value"" and ""fair market value"", to name a few, although in the mining industry, valuations usually refer to fair market value.In the Canadian mining industry, at present, there are no comprehensive regulations or guidelines that specify which approaches or methods are appropriate for use in the valuation of mineral projects. In January 1999, The Mining Standards Task Force of the Toronto Stock Exchange and the Ontario Securities Commission recommended that the Canadian Institute of Mining, Metallurgy and Petroleum establish a committee to review and advise on approaches and methodologies for the valuation of mineral properties. Among the approaches to be considered, are included the following: the Discounted Cash Flow Approach, the Cost Approach, the Option Pricing Approach and Market Comparables Approach. In addition, methodologies differ depending on whether the project is at the exploration stage or the producing stage.The CIMVal committee expects that its final report will form the basis for a standard Canadian Code for the valuation of mineral properties."

Jan 1, 2003

By Jo Render

Expectations of your management approach ??Life of mine applicability ??Tailor scale of activity to scale of project ??Assess impacts, risks, and opportunities ??Use global good practice, backed up by rigorous analysis ??Support with trained monitoring and evaluation team ??Information infrastructure to allow ongoing trend analysis and tracking of progress ??Public reporting using standardized indicators Yes, we are talking about a ?management system?

May 1, 2011

By Harold L. Gibson, David H. Watkinson

"Volcanogenic massive sulphide deposits of the Noranda Camp cur throughout the Noranda Shield Volcano but are concentrated and along the margins of the Noranda Cauldron. The deposits are realized along synvolcanic faults that also accommodated subsince and controlled the location of eruptive centres. Deposits within e 3 000 m thick Mine Sequence formed during a period of active volcanism and subsidence coinciding with the onset of two cauldron subsidence cycles. The Noranda Cauldron was a restricted site of 10malously high heat flow and structural permeability that favoured e development of a high-temperature hydrothermal system. Metals may have been derived from leaching of aquifer rocks by convecting a water or directly from a shallow underlying magma chamber, now presented by the Plavrian Pluton, that was at its highest position !thin the crust during cauldron subsidence. The deposits formed rough a combination of sulphide precipitation from exhaled fluid td replacement at and below the seafloor in a manner analogous to ose on the modern seafloor.RESUMESi les dépôts de sulfures massifs volcano gènes du camp minier de ~uyn-Noranda sont présents dans les différentes parties du volcanluclier de Noranda, ils se trouvent concentres toutefois, en plus ·and nombre, sur le pourtour de la caldeira (cauldron) de Noranda. ~s dépôts sont localises le long des failles synvolcaniques qui ont cilite la subsidence et contrôle la position des centres d’éruption.~dépôts situes dans la séquence des mines (3 000 m d’épaisseur) sont formes durant un épisode d' activité volcanique et de subsiden qui coïncide avec l' amorce de deux cycles d' affaissement de la rldera (cauldron) de Noranda. Celle-ci Jut le site exclusif d’unflux : chaleur anormalement élevé et d’une perméabilité d’origine cucturale qui ont favorise le développement d’un système hydrothermal a haute température. Les métaux proviennent soit directement d’une chambre magmatique situee afaible profondeur, so it d’un lessivage des roches de l’aquifère par l’eau de mer circulant par convection. Cette chambre magmatique, représentée maintenant par le pluton de Flavrian, se trouvait à son niveau le plus élevé dans la croute au moment de l’affaissement de la caldeira (cauldron). Les dépôts se sont constitués par un mecanisme combinant remplacement et précipitation de sulfures à partir des fluides exhalatifs, au niveau ou au-dessous du plancher océanique, de la même manière que se forment de nos jours, les dépôts de sulfures massifs au fond des océans."

Jan 1, 1990

By A. R. Hekmat

Hypereutectic Al-Si alloys are used in applications that require high resistance to wear and corrosion, hardness and low coefficient of thermal expansion, To maximize the properties of these alloys, semi-solid processing can be utilized to modify the solidification structure of the primary silicon crystals as well as to reduce microsegregation and porosity, The transformation and spheroidization of primary Si crystals by shearing in the semi-solid state are not fully understood as they precipitate in the presence of other alloy phases, The objective of the present work is the determination the rheological characteristics of A390 (Al-17%Si-4,5%Cu-0.5%Mg) alloy using a Couette type (Haake RV12) viscometer and examining the microstructural evolution during continuous cooling and isothermal shear rate experiments, The effect of shear rate, solid fraction (temperature) and morphological evolution of the silicon crystals are investigated.

Jan 1, 2005

By N. Torres, G. Melcher

"An alternative to building new copper smelters, because of either stringent environmental regulations or in order to expand current plant capacity, could be achieved through the retrofitting of old reverberatory furnaces by making use of tonnage oxygen. The CONTOP® technology offers unique advantages over other techniques for this purpose, especially regarding substantial reduction in bath, capital and operating costs. This is possible to achieve since the reverb throughput could be largely increased with no major structural modifications to the furnace.The following options are offered to the smelter operators: dirty concentrates can be treated in an adjacent Contop system, or the cyclones can be mounted on the reverb roof for either dual operation or full Contop operation. ln the tatter case the furnace will be used as a settling chamber and f or slag c1eaning by top blowing with reducing gases.By incorporating Contop technology, the furnace throughput can be increased, higher malle grade, fixation of sulphur from furnace off-gas and substantial savings in energy consumption are possible to attain.IntroductionCopper smelting has been revolutionized during the last quarter century to such an extent that the standard type of plants consisting o f roasters and reverb furnaces seem a thing of the past, or almost. Though the building of new, more energy efficient smelters is a very likely opportunity for a grassroots plant, it would be hardly justifiable to replace an old existing plant unless there are heavy environmental or economic constraints(1,2,3)."

Jan 1, 1984