The reinforcement of an Al casting with ferrous inserts (hybrid systems) through a joining technique to utilize both Al alloys (lightness) and Fe-based alloys (stiffness) is of interest, especially in the transportation sector. This work focuses on different technological aspects of cast joining of cast iron to an Al alloy using an intermediate material (or coating). The experimental set up consisted of preparing the insert surface followed by coating the insert, and then, immersing it into an Al melt, and allowing the system to cool down to room temperature. The effects of flux treatment, decarburization, and the coating application, as well as the immersion time in the Al melt on the Al-Fe joint quality were investigated. The microstructure evolution of the reaction layer forming at the insert-coating interface was determined as a function of the coating time and the coating composition, and their effects on the joint properties were evaluated. The relationship between the microstructure and microhardness of the joint zone was established. Decarburization, flux treatment, suitable coating, and optimizing the process parameters improved the joint properties. Combination of "McGill 2" coating alloy and 1 min immersion time (in the Al melt) resulted in the formation of an Al-Fe joint with optimized characteristics. The results showed that the cast joining could be used to strengthen the Al castings and improve their performance. / Le renfort des pièces coulées en aluminium par l'assemblage d'insertions ferreuses (systèmes hybrides) permet de combiner la légèreté de l'aluminium avec la rigidité des alliages à base de fer. Cette technique présente donc un grand intérêt pour plusieurs applications, spécialement dans le secteur des transports. Ce projet porte sur les différents aspects technologiques de la coulée de pièces avec joint aluminium-fonte auquel est ajouté une couche intermédiaire (ou revêtement). La procédure expérimentale a consisté à préparer la surface des insertions, à appliquer le revêtement, puis immerger la pièce dans un bain d'aluminium liquide, pour finalement refroidir le système jusqu'à la température de la pièce. Les effets du traitement par flux, de la décarburisation, et des paramètres de revêtement ainsi que la durée d'immersion dans l'aluminium liquide sur la qualité du joint aluminium-fonte ont été étudiés. L'évolution de la microstructure par la formation d'une zone de réaction à l'interface de l'insertion de réaction et zone du revêtement a été déterminée en fonction de la composition du revêtement er du temps d'immersion dans le revêtement liquide, et leurs effets sur les propriétés du joint été évalués. La corrélation entre la microstructure et la microdureté du joint ont a été établie. La décarburisation, le traitement par flux, l'utilisation d'un revêtement approprié et l'optimisation des paramètres du procédé améliorent significativement les propriétés du joint. L'utilisation du revêtement "McGill 2" avec un temps d'immersion dans le bain d'aluminium d'une minute permet la formation d'un joint Al-Fe avec des caractéristiques morphologiques, d'épaisseur, de microdureté et de composition optimisées. Les résultats montrent que l'insertion de pièces formant un joint peut être utilisée pour renforcer les pièces d'aluminium et

A Falcon model B6 was tested on a massive gold-copper sulphide ore (AgnicoEagleLaRonde Division, AELR), to assess its ability to produce a smeltable concentrate(200000 to 300000 g/t); a fine gold-pyrite-silica flotation tail (Meston Resources, MR)to assess the Falcon's ability to recover gold from a low density and very fine material;and a synthetic magnetite-silica ore to obtain more fundamental information on its modeof operation.For 20 kg of AELR's flotation concentrate fed at 20 to 30% solids at 20-30 l/min,the Falcon recovered 22 ± 3% of the gold at a grade of 900 g/t. It overloaded whenmore than 20 kg of material was processed and recovery dropped sharply.Samples of MR's flotation tails were processed with the Falcon. Three differentbowls (8, 10, 14 degree) were tested at two flowrates (10,20 L/min), and three densities(10,20,30 %w/w). None of theparameters were found significant for pyrite, but bowlangle and flowrate were found to be significant for gold. On average, the Falconrecovered 50% of the gold and 20% of the pyrite at a concentrate grade of 4.0 g/t goldin a weight yield of 10%.Three 3-level nested factorial experiments were performed with an artificial feedconsisting of silica and magnetite to study the effect of gangue particle size, bowl type,% solids, and flowrate. A typical loading cycle includes (i) the initial unselectivecreation of a first concentrate bed; (ii) more selective recovery as bed growth stops and(iii) saturation of the bed surface leading to a zero incremental recovery .A sythetic feed (5% magnetite, p5% silica) was used to characterize the Falcon'sloading cycle, its overload, and the effect of operating variables. Overload with thesynthetic feed was virtually complete upon feeding 30 kg, either at 20 or 30 L/min.Three 3-level nested factorial experiments showed that for a constant mass of thesynthetic feed, magnetite recovery increased with decreasing particle size and bowl angle.These effects masked the impact of feed flowrat / Le separateur Falcon est un nouvel appareil centrifuge qui a ere concu pourrecuperer de l'or fin « 53ILm). Cette etude visait a mieux comprendre sonfonctionnement.Un concentre de flottation de la mine Agnico-Eagle, Division LaRonde (75%de pyrite, 200 g/t d'or) a ere traite avec un separateur Falcon afin de produire unconcentre fusionable (200000 a 300000 g/t). Pour une masse traitee de 20 kg, lemeilleur rendement (recuperation d'or: 22 ± 3%; teneur du concentre: 900 g/t) a eteatteint aune densite de 20 a30 l/min, et un debit de 20 a 30 l/min al'alimentation.On a note qu'en augmentant la masse de 20 a80 kilogrammes, la recuperation d'ora diminue de facon tres marquee.On a effectue une deuxieme serie d'essais avec un rejet de flottation tres finde la mine Meston (60% de silice, 1% de pyrite, 1 g/t d'or) afin de reduire les pertesd'or du circuit de flottation. En moyenne, le Falcon a pu recuperer 50% de l'or desrejets, dans un concentre de 4 g/t qui pourrait etre cyanure.Une derniere serie d'essai a ete completee avec une alimentation synthetique(95% de silice et 5% de magnetite) afin de preciser le fonctionnement du Falcon etd'identifier le lien entre la recuperation et les conditions d'operation. Le bol a l'anglele plus aigu, 8°, en presence de la gangue fine, -75 ILm, a permis de maximiser larecuperation de magnetite. Plus precisement, la recuperation de magnetite etait pluselevee pour les tailles granulometrique tres fines « 50 ILm), moyenne pour les taillesgrossieres (+ 200 JLm), et faible pour le reste.On a identifie 3 etapes qui caracterisent le cycle de fonctionnement duseparateur: i) au debut du cyle, l'accumulation de solides contre la paroi du bol, etla formation d'une couche de concentre; ii) une phase de recuperation selective a lasurface de la premiere couche du concentre; iii) et la saturation ala surface vers lafin du cycle. fr

The subject of this work is nickel extraction from dilute, acidic sulphate solutions through the use of organophosphorous acid reagents. The focus is primarily on OPAP, a mixed extractant consisting of mono- and di-octyl phenyl phosphoric acids, as well as on di-(2-ethyl hexyl) phosphoric acid (D2EHPA). The effects of certain parameters on the extraction of nickel, both quantitative and qualitative, have been studied. The parameters include: modifier presence, concentration and type; OPAP concentration; phase ratio; aqueous environment; age of organic solution; and mono-/di-OPAP ratio. The ability to strip nickel from the organic solution as well as selectivity and kinetic tests were carried out. / The use of 10% isodecanol as a modifier was found to be essential for the purpose of OPAP solubility in kerosene and phase separation. Furthermore, the cation exchange reaction proceeds very quickly, attaining equilibrium within 10 minutes. Unlike other phosphoric acid reagents, OPAP is able to extract significant amounts of nickel in the acidic pH range of 1 to 2. As well, nickel is easily stripped using a 1.0 M sulphuric acid solution.

A method of inclusion measurement in molten metals, known as the Liquid Metal Cleanness Analysis or LiMCA, currently in use for aluminum, has been developed for high temperature and reactive industrial metals. / LiMCA probe consists of an electrically insulating sampling tube with two electrodes, in- and outside the tube. The sampling tube also incorporates a small orifice through which molten metal is aspirated. As suspended inclusions pass through the orifice, and in the presence of an electric current, voltage pulses are generated. By measuring and counting such pulses electronically, the size distribution of inclusions can be obtained. The orifice, therefore, serves as an Electric Sensing Zone (ESZ) for the probe. / This work presents an analysis of LiMCA's electric circuitry, and the design and operation of LiMCA probes in steels, copper and magnesium alloys.

Yield stresses and r-values were measured as a function of inclination with respect to the rolling direction on thirty-one steels selected from high strength low alloy (HSLA), Al-killed (AKDQ), interstitial free (IF1 and IF2) and rimmed (RIM) types. Modul-r and electromagnetic acoustic (EMAT) techniques were employed to determine the elastic anisotropy in terms of the angular variation of Young's modulus and the ultrasonic velocities, respectively. Orientation distribution functions (ODF's) were also measured for these steels in their as-received states and after deformation in tension and in drawing. The various initial textures and their evolutions along the latter strain path are analyzed in terms of the 4- and 6-ear behaviours commonly observed during the forming of cylindrical cups. / The series expansion method was employed for predicting the elastic and plastic anisotropies from the initial texture data. Comparison with the experimental measurements of Young's modulus indicates that the so-called elastic energy method can accurately reproduce the elastic anisotropy if the single crystal elastic constants are appropriately chosen within their ranges of uncertainty. The systematic evaluation of various grain interaction models for predicting the polycrystal plastic anisotropy reveals that the "pancake" relaxed constraint model is a more accurate predictor of the behaviour than the Taylor, Sachs-Kochendorfer, or other relaxed constraint models. The best quantitative agreement is obtained when the critical resolved shear stress (CRSS) ratio for glide on the $ {112 } langle 111 rangle$ and $ {110 } langle 111 rangle$ systems is 0.95 (except for the AKDQ and IF2 grades, for which values of 0.90 and 1.0, respectively, are preferred). / The ODF coefficients of order greater than 4 were evaluated and calculated non-destructively from the anisotropy of the ultrasonic velocities of the lowest order symmetrical Lamb (S$ sb{ rm o}$) and shear horizontal (SH$ sb{ rm o}$) waves propagating in the rolling plane. The elastic energy method was employed, together with a decomposition of the texture into the principal preferred orientations. The calculated pole figures based on the ODF coefficients obtained in this way are similar to those derived from complete X-ray data. It is shown that the plastic properties of commercial deep drawing steels are predicted more accurately when the 4th and 6th order ODF coefficients are employed than when only the 4th order ones are used.

Softening represents one of the stages in the pyrometallurgical refining of lead, in which oxygen is top-blown into a bath of impure bullion through a group of lances in order to preferentially oxidize arsenic, antimony and tin dissolved in the melt. The oxides of these species float to the melt surface, where they are removed as dross. / It has been observed at Teck Cominco Lead Operations in Trail, BC that there is an "ignition temperature" in the range of 600°C, below which the softening reactions are reported to occur very slowly, if at all. Currently, disproportionately large efforts are made to initiate and sustain the softening process. This research was motivated by Teck Cominco's wish to have a clearer understanding of the ignition temperature phenomena, and a more robust and reliable process control. / Experimental trials were performed using a homemade thermogravimetric analyzer with a data acquisition system. The unit was constructed in such a way as to allow for simultaneous video recording of the sample surface, for future examination and reference.

An experimental study of minor element elimination from copper smelter dust by vacuum calcination was carried out. The rationale for the study was to test the feasibility of vacuum calcination as a treatment to separate minor elements from copper smelter dusts and to recover the copper values in the dust. / The physical, chemical and mineralogical nature of copper smelter dust as received was characterized using ICP, AA, XRD, EDS etc. The prevailing mineralogical components of the dust were copper sulfate, lead sulfate and magnetite. It was observed that the dust particles consisted of spherical and irregular shaped agglomerated solid droplets. / Experiments were performed to measure the extent of removal of bismuth, arsenic, lead and zinc from copper smelter dust exposed to a vacuum in the range from 50 to 110 Pascal in the temperature range from 600 °C to 950 °C and for a time in the range from 30 minutes to 90 minutes. Fifty gram samples of smelter dust were used in each test. It was found that up to 97 % Bi, 99 % As and 99 % Pb eliminations from the dust were achieved in experiments, performed at 900 °C, in the pressure of 50~110 Pa and for a period of 60 minutes with the addition of copper concentrate in different ratios. (Abstract shortened by UMI.)

The high strength of TRIP (TRansformation Induced Plasticity) steel enables high fuel efficiency by reducing the weight of a car without any loss of safety. In addition, the good formability shown by TRIP steel extends the application of this type of steel to complicated component shapes. TRIP steels can be used in the cold rolled and 'TRIP annealed' condition. After cold rolling, TRIP steels are subjected to a complicated anneal/heat-treatment encompassing intercritical annealing followed by bainitic transformation. Because the 'TRIP annealing' is designed to produce the complex microstructures, comprised of ferrite, bainite, retained austenite, which achieve the best combination of strength and formability; the processing of these steels requires careful selection and delicate control of temperatures and holding times. In this context, this research work has been carried out to design an alternative process for TRIP steel, using a relatively simple subcritical heat-treating process. Basically, the concept is to cold roll the TRIP steel to produce strain induced martensite, as well as work hardened ferrite and bainite, and then to 'conventionally' anneal the steel to produce tempered martensite and bainite, as well as recrystallized ferrite. For this purpose, 'subcritical heat treatment' of multiphase cold rolled TRIP steel at 200, 300, 400, 500, 550, 600, 650ºC for a hour were done then the microstructure, mechanical properties were investigated with x-ray diffraction, OM and SEM, tensile testing and hardness measuring. The mechanical properties after the subcritical heat treatment at 600ºC and over are approaching those of traditional TRIP processed steel hence this process can be a promising alternative and worth further study.

Strips of magnesium (A-Z91 and AM50) and aluminum (AA6111) alloys were cast on a moving mold system devised for simulating single belt casting operations. Different type of substrates were used for the moving mold; copper, low carbon steel, alumina coated steel, nickel coated steel, and zirconia coated steel. Interfacial heat fluxes between the solidifying strip and the moving mold substrate were calculated by the IHCP (Inverse Heat Conduction Problem) technique. The temperature history of the solidifying strip was calculated using the Enthalpy FVM (Finite Volume Method) associated with Scheil's model of solidification. The influence of thermophysical and morphological properties of mold substrates, wetting environment, casting speed, melt superheat, and grain refiner, on strip microstructures and their cooling rates, were thoroughly investigated. / Maximum heat fluxes appeared about 0.1~0.2 seconds after the moment of thermal contact. For a copper substrate, these reached up to 7 MW/m 2, whereas those for a steel substrate were ~3 MW/m2. The rate of heat transfer to coated substrates was significantly delayed and reduced because of the low thermal conductivity of coating layers. Maximum cooling rates of aluminum and magnesium strips reached about 200°C/s on copper and about 150°C/s on steel. / It was found that the major thermal resistance resided in an interfacial layer separating the strip from the substrate. This interfacial layer presumably corresponded to the shrinkage of solidified skin or the entrainment of a thin air film resulting in numerous air pockets at the bottom surface of strips. Oil spraying onto the mold surface changed the interfacial wettability and dramatically improved the cast surface of the strips. The good quality of strip samples obtained suggests the high potential for the direct casting of these alloys on single belt casters.

There currently exists no available model for predicting the Sauter mean bubble diameter, D32, from the key process variables for mechanical flotation machines. This is seen as a significant shortcoming since flotation is a surface area (of bubbles) dependent process, the key metric being the bubble surface area flux, Sb, defined as 6 Jg/ D32, where Jg is the superficial gas velocity. Knowledge of how key variables affect the bubble size distribution (BSD), and hence Sb, is seen as an essential component of process understanding and optimization. The objective of this work was to develop a mathematical expression for D32 based on the key process variables of frother type and concentration, superficial gas velocity, power intensity (impeller tip speed), liquid viscosity, and altitude (elevation above sea level). In order to effectively measure the BSD that links to the Sb leaving the pulp phase, a relatively large 700 liter cell, a Metso RCS™ 0.8 m3 pilot unit, was selected. This unit, having an internal shelf baffle, produced separation of turbulent (near impeller) and quiescent (near froth) regions, ensuring that the measured BSD was truly reflective of the surface area flux leaving the pulp zone. Failure to adequately address this has been a shortcoming of work by others. The Metso unit was powered by a variable speed drive that permitted an 8-fold increase in power intensity covering the full range of industrial impeller tip speed (4.6 to 9.2 m/s). Five frothers were tested, covering a broad range in types including alcohols and polyglycols, Viscosity was modeled by varying water temperature between 4 and 40 oC. Altitude was modeled by varying gas density, an air-helium mixture fed to a smaller 5.5 liter laboratory Denver cell. The McGill gas dispersion sensors; bubble viewer and Jg probe, were used for measurement. The work showed that the effect on D32 for all frothers can be normalized to the same set of curves when dividing concentration by a frother's CCC95 value. The notion of CCC95 is introduced and is equivalent to Laskowski's CCC (critical coalescence concentration) but more suitable for mathematical analysis and model development. It represents the frother concentration (ppm) for which 95% reduction in D32 has been achieved. Frother concentration was found to be the variable with the largest impact on D32 and is modeled with an exponential decay function that reaches a limiting bubble size at frother concentration exceeding the CCC95 value. Higher CCC95 results in a lower limiting bubble size. It appears that the CCC95 value for a frother may be predicted from its' basic molecular structure using the Hydrophile-Lipophile Balance/Mol. Wt. parameter. It was also found that the CCC95 value for a frother increases with increasing Jg. D32 was found to depend on Jg0.5 with a notional "bubble creation size" at Jg = 0 cm/s. The dependence on viscosity relative to that at 20 oC was a power relationship having an exponent of 0.776, while similarly, that for simulated altitude (gas density relative to air density at sea level)) showed less dependency with an exponent of -0.132. Surprisingly, impeller speed was found not to have any significant effect on D32 across the range representing an 8-fold increase in power intensity and a doubling of impeller tip speed.The overall D32 model, developed in a 2-phase air-water system, shows very good agreement with measured plant data from 5 operating sites worldwide, representing 3-phase (air-water-solids) flotation systems. The Sb- Jg curves produced by the model can be used as a "road-map" to benchmark plant operation as illustrated by a case study from the Lac des Iles palladium mine in Ontario. This approach is seen as a significant development for process understanding and optimization. / Présentement aucun modèle ne permet de prédire le diamètre moyen de Sauter d'une bulle, D32, dans une cellule mécanique de flottation à partir des variables clés de ce même procédé. Cette lacune est significative puisque la flottation est un procédé dépendant de l'aire surfacique (des bulles), le paramètre clé étant le flux d'aire surfacique de bulles, Sb, défini comme étant 6 Jg/D32 où Jg est la vélocité superficielle du gaz. La façon dont les variables clés influencent la distribution des tailles de bulles (DTB) et par conséquent Sb est une confirmation essentielle pour comprendre et optimiser le procédé.L'objectif de travaux de recherche de cette thèse est de développer une expression mathématique pour la détermination du D32 basée sur des variables clés : type et concentration du moussant, vélocité superficielle du gaz, puissance d'agitation, viscosité du liquide et l'altitude (élévation au-dessus du niveau de la mer).Afin de mesurer efficacement la DTB en lien avec le Sb des bulles quittant la phase de pulpe, une cellule relativement grande (700 litres) soit une unité pilote Metso RCSTM de 0,8 m3, a été choisie. Cette unité, qui a un plateau déflecteur interne, produit une séparation des zones de turbulence (près de l'agitateur) et de quiescence (près de l'écume) assurant ainsi que la DTB mesurée est le reflet exact de flux surfacique de bulles quittant la pulpe. Cette démarche constitue en soit une contribution importante car elle rectifie une mauvaise interprétation souvent retrouvée dans les travaux d'autres chercheurs.Les travaux entrepris ont aussi permis de découvrir que le D32 est fonction du Jg 0,5 avec une notion de « création de la taille de bulle » à Jg = 0 cm/s. Le D32 est également fonction de la viscosité à 20 ºC par une relation de puissance avec un exposant de 0,776, alors quelle a moins de dépendance à (densité de gaz) avec un exposant de -0,132.De façon surprenante, il a été découvert que la vitesse de l'agitateur n'avait pas un effet significatif sur le D32 dans la plage testée, soit une augmentation de l'intensité de puissance de l'ordre de 8 fois et le doublement de la vitesse en bout de l'agitateur. Il est postulé que les conditions hydrodynamiques à l'intérieur de la zone agitateur/stator sont celles où le niveau élevé de turbulence à écoulement libre et la fraction de vide élevée (taux de rétention de gaz) résultent en un coefficient de traînée non constant plus bas pour les bulles individuelles, signifiant une force (perturbatrice) de traînée moins dépendante de la vélocité relative des fluides mais avec plus d'effet de viscosité.Finalement, le modèle D32 développé pour un système biphasé (air-eau) montre une bonne concordance avec les données mesurées en usine dans 5 sites industriels, représentant des systèmes de flottation à 3 phases (air-eau-solides). Les courbes Sb-Jg produites par le modèle peuvent être utilisées comme un abaque pour étalonner les opérations en usine tel qu'illustré par l'étude de cas de la mine de palladium du Lac des Îles en Ontario confirmant ainsi l'utilité du modèle, une avancé en soit pour la compréhension et l'optimisation du procédé de flottation.