Microwave Processing of Minerals
Supervisor: Kristian Waters
Plasma Source Design and Instrumentation
Supervisor: Sylvain Coulombe
Parallel Implementation of Crystal Dynamics for GPU Computing
Supervisor: Kirk Bevan
Surface Functionalization of Scaffolds for Bone Regeneration
Supervisor: Marta Cerruti
Gravity Concentration of Talc
Supervisor: Kristian Waters
Microwave Processing of Minerals
Supervisor: Kristian Waters
Thermodynamic Modeling of Oxide Systems for Pyrometallurgical Applications Supervisor: In-Ho Jung
Magnesium Alloy Solid State Processing
Supervisor: Stephen Yue
kirk.bevan [at] mcgill.ca (KIRK BEVAN)
Parallel Implementation of Crystal Dynamics For GPU Compting (Nanotechnology & Advanced Materials) - The S.U.R.E student will implement/extend the development of a computing code for the acceleration of nanomaterials growth/dynamics on a massively parallel graphics processing unit (GPU) computing platform.
mathieu.brochu [at] mcgill.ca (MATHIEU BROCHU)
Strain-induced Spark Plasma Consolidation of advanced powders (Bulk Nanomaterials) - Many structural metals are processed by powder metallurgy methods because of the fine microstructural control and excellent properties attainable; however, typical sintering processes at high temperatures for long times encourage grain growth. This is especially pronounced in materials with nanometric grain size, so novel alternatives to conventional sintering are being explored. In metals that undergo allotropic phase transformations, densification can be enhanced by cycling the sintering temperature around the transformation temperature. This project aims to increase the current understanding of the mechanisms of this process, and to apply the concept to the processing of fully dense, nanograined metallic materials (particularly iron and titanium). In addition to conventional powder metallurgy methods, spark-plasma sintering will be used as a tool to further prevent grain growth, making very high strength products possible.
Amorphous Alloys Formation From Recycled Aluminum (Nanotechnology & Advanced Materials) - Production of amorphous aluminum alloys is currently one of the cutting-edge research topics in materials engineering. The ever-growing interest for these alloys finds its origin in their exceptional properties and their broad range of applications (golf club, high-reliability electronics,…). Since amorphous alloys contains a wide variety of alloying elements to disrupt the crystalline structure, the utilization of a mixtures of low-grade Al will be investigated as a potential method to use this low-value material towards a high-end application. Particularly, in order to increase the downstream profitability through recycling materials from industry, aerospace components coming from airplanes graveyards will be used as base material to produce these high-added value alloys.
marta.cerruti [at] mcgill.ca ( MARTA CERRUTI )
Surface Functionalization of Scaffolds for Bone Regeneration (Biomaterials) - Biodegradable scaffolds are porous polymeric materials that can be used to promote the healing of fractured or diseased tissues. The surface of the scaffold is the first region that cells get in contact with after surgical implantation, and determines the success or failure of the implant. A successful scaffold must have a surface that favors cell adhesion, spreading and proliferation, thus actively promoting the process of tissue reconstruction. For orthopedic applications, surface modification can help the formation of hydroxyapatite, the mineral component of bones. Coating the scaffolds with a layer of this mineral helps the formation of bone around the scaffolds. In this project, we will develop different surface modification techniques that will allow scaffolds to mineralize more effectively once immersed in simulated body fluids. Scaffolds are produced with a simple technique that leads to porous materials in a few days. The surface modification involves the formation of stable chemical bonds between the scaffold and molecules possessing groups that favor the deposition of hydroxyapatite. Mineralization tests will be conducted in acellular solutions at first, and preliminary tests involving cells may be performed too.
jim.finch [at] mcgill.ca (JIM FINCH)
The Effect of Solids Particles on Bubble Coalescence (Mineral Processing) - Frothers and certain inorganic salts have been shown to inhibit bubble coalescence (Lessard and Zieminski, 1971; Grau and Laskowski, 2006). Kracht and Finch (2009) presented ‘coalescence plots’ which indicate a transition in bubble regimes: from single bubble production to bubble coalescence for bubbles produced at a 200 µm capillary. The technique employed high speed photography and acoustic emission monitoring to identify the air flow rate at which the transition occurred. The presence of flotation frothers (MIBC, DF-250, F-150) and a series or n-alcohols inhibited coalescence with increasing surfactant concentration (i.e., the transition moved to higher air flow rates). The aim of the current project is to study the effect of hydrophobic (talc) and hydrophilic (silica) solid particles on bubble coalescence at a capillary in water at increasing solids concentrations in various frother and inorganic salt solutions. Setup: Bubbles will be produced at a 200 µm capillary in an acrylic tank. Air will be supplied via a compressed air bottle with regulator connected to a 0-100 sccm mass flow meter. The transition between the single bubble regime and coalescence regime will be determined using high speed photography and acoustic emission monitoring.
Using XPS to Analyze Oxidation Products (Mineral Processing) - One of our ongoing projects in the Department of Mining and Material Engineering has been the study of self-heating sulphides. Our primary objectives are to better understand the chemistry of these reactions and to find mitigation methods that can reduce and / or prevent self-heating from creating hazardous environments. We know that some sulphides are prone to self-heating and that the degree of self-heating of these sulphides is influenced by their exposure to specific atmospheric conditions. We also know that for these materials oxidize to form elemental sulfur and other (yet to be determined) oxidation products. The SURE 2012 project would be to use XPS and possibly other analytical methods (Micro Probe etc.) to identify some of the other oxidation products formed during controlled weathering conditions. This work will familiarize the students with the various techniques of weathering the samples and testing them for self-heating. The students will also be trained in the use of the various analytical methodologies.
Effect of Soda Ash on Pentlandite/Serpentine Aggregation (Mineral Processing) - Aggregation is usually counterproductive to physical separation processes unless selective aggregation can be achieved. A common form of aggregation is slime coating. Presence of serpentine minerals hinders pentlandite flotation by slime coating in processing ultramafic Ni-ores. By experience it has been found that soda ash gives the best flotation recovery and grade for ultramafic ores. Soda ash is a pH modifier and considered to be a dispersant at the same time.
Dispersants are reagents used to promote and keep particles dispersed. Soda ash is a widely used pH modifier in Ni-ore flotation. Surface charge measurements at pH 10 (using soda ash as pH modifier) show that both pentlandite and serpentine have negative charge which means an electrostatic repulsion is expected between them. Electrostatic repulsion should promote dispersion. However, dispersion studies did not confirm that; soda ash did not significantly improve dispersion. Mixed mineral zeta potential studies will be performed to determine the effect of soda ash on surface charge of pentlandite and serpentine when they are in contact. The state of dispersion will be visualized using scanning electron microscope (SEM).
jean-luc.meunier [at] mcgill.ca (RAYNALD GAUVIN & JEAN LUC MEUNIER)
Studies on Aluminum – Carbon Nanotubes Composites Formation (Advanced Materials & Polymers) - Important efforts are made worldwide (particularly in Korea for the car industry) to generate aluminum – carbon nanotube (Al-CNT) composites for enhanced structural and transport properties. Our teams in Chemical and Materials Eng. have worked on trying to generate such composite structures. Results indicate a strong difficulty for a proper mixing of the two phases, the CNT agglomeration being a consistent bottleneck in the process. Techniques have however been developed at McGill to grow CNT directly as a nano-scale forest on stainless-steel (SS) particles; this technique was in fact expanded in a fluidized bed chemical vapor deposition (CVD) system. Other preliminary results showed this growth technique could be transferred to aluminum metal, and to aluminum samples having a specific anodized aluminum oxide (AAO) surface. The result on Al metal needs to be confirmed and studied using our conventional CVD furnaces and various Al-based alloys. If CNT growth on Al metal proves to be comparable to the SS system, the fluidized bed technique could be applied to generate a large amount of precursor for Al-CNT composite consolidation. Another avenue we currently use is a plasma-based surface functionalization of the CNTs to make them hydrophilic. This is typically made with polar groups for water dispersion and would not really be applicable to aluminum. However, we also decorate the tubes with well dispersed nanoparticles on the entire CNT forest; Al nanoparticles being possible candidates. Such dispersion of nanoparticles having a strong bonding interaction with the CNTs should allow improved wetting properties of these nanostructures in the liquid metal. If the decorated CNTs are maintained on the metallic substrate (typically SS), the good heat transfer phenomena should maintain the integrity of the Al nanoparticles during liquid-Al impregnation. Tests along this idea of creating first an Al-CNT composite layer on a substrate will be made during the summer project. Such testing involves growing the CNT layer on SS, decorating the CNT with Al nanoparticles using laser ablation, and then impregnation.
in-ho.jung [at] mcgill.ca ( IN-HO JUNG)
Thermodynamic Modeling of Oxide Systems for Pyrometallurgical Applications (Hydrometallurgy Pyrometallurgy) - This project requires the deep understanding of metallurgical thermodynamics. All experimental data related to phase diagram and thermodynamic properties in literature will be collected and critically evaluated. Then, based on the thermodynamic model for each phase, the experimental data will be converted into Gibbs energy functions. The Gibbs energy functions can be used for the FactSage software to draw the phase diagram and calculate multicomponent thermodynamic equilibria
Experimental Phase Diagram Study for Metallic and Oxide Systems (Hydrometallurgy - Pyrometallurgy) - This project requires the understanding the phase diagram and metallographic technique. The binary or ternary phase diagram of metallic or oxide system will be investigated. The materials of given composition will be equlibrated at high temperature furnace. After quenching the samples, the phases in the sample will be identified by SEM,XRD and EPMA techniques. Experimental results will be compared with previous experimental data and the thermodynamic predictions from FactSage.
frank.mucciardi [at] mcgill.ca (MUCCIARDI & HASSANI )
Conversion of Waste Heat to Electricity with a Heat Pipe Engine ( Energy) - Many industrial processes consume energy. In most cases however, only a fraction of this energy is used by the process. The rest of the energy is typically released to the environment in a variety of ways - one of these being the venting of hot exhaust up a stack. To date, little has been done to recover some of this energy besides the obvious of heating up work spaces and/or providing hot water requirements. One idea that is gaining acceptance is to use some of the waste heat to produce electricity. There are several processes for doing this. The most common is referred to as the Organic Rankine Cycle (ORC). It is modeled after the classic Rankine cycle which produces electricity by having steam drive a turbine. During the last few years, we have been working at McGill to develop an alternative process for the capture, concentration and conversion of low grade waste heat to electricity, i.e. the 3 C's. The process we have put together uses heat pipes to capture and concentrate the waste heat. The conversion of the concentrated heat to electricity is carried out by a ‘heat pipe engine’ that we are developing at McGill. The engine is based on a piston-cylinder arrangement (as opposed to a turbine) to create mechanical work which is converted to electricity. This method of producing electricity is a novel combination that is not found in the literature. To date, we have shown that heat pipe technology can capture and concentrate waste heat. We now need to show that the heat pipe engine can convert some of this waste heat to electricity. We are currently building a small scale prototype of the engine. What will be done during the summer will be to run extensive tests with the engine and to gather operating data. In addition, the student will work with a graduate student to develop a mathematical model that describes the heat pipe engine.
nate.quitoriano [at] mcgill.ca (NATE QUITORIANO)
Dye Sensitized Solar Cells (Nanotechnology & Advanced Materials) - Dye sensitized solar cells (DSSCs) is a promising technology to convert solar (light) energy into electric energy. DSSCs typically use TiO2 particles and ruthenium-based dyes to convert the light into electricity. Currently these solar cells are produced by spreading TiO2 particles over glass using a screen printing technique. This project will seek to understand if a new technique can be used to deposit the TiO2 particles, cold spray, a process where particles of materials are propelled up to 3600 km/hr onto a substrate. Cold-spray-deposited TiO2 for DSSCs would enable fast assembly-line-like fabrication of DSSCs. During this project, the student will fabricate DSSCs from samples which have TiO2 layers that have been sprayed onto the surface. The student will add the dye and construct and characterize these cells using a solar simulator and electrical probes. If the student is successful in fabricating DSSCs using cold-spray-deposited TiO2, a paper describing their results may be published describing their findings
jun.song2 [at] mcgill.ca (JUN SONG)
Atomistic Design of Mg Alloys Containing Rare Earth Elements (Nanotechnology & Advanced Materials) - In this proposed project we plan to study the role of various rare earth elements (e.g., Nd, Y, Ce) on the deformation mechanisms of Mg alloys. In particular, we will utilize atomistic simulations to examine the energetics and segregation of these rare earth elements at different dislocation core structures. The subsequent deformation behaviours of those dislocation core structures under shear stresses, with and without the rare earth alloying elements will be investigated in details, so as to assess the effects of rare earth elements on competition among slip systems (e.g., basal, prism, pyramidal and mixed modes) within hexagonal close-packed (HCP) Mg. Besides simulations, micromechanics modeling will also be performed to help connect the identified atomic-level details with macroscopic plasticity. These combined results are expected to provide some mechanistic insights towards the optimal design of Mg alloys containing rare earth elements.
kristian.waters [at] mcgill.ca ( KRISTIAN WATERS )
Applying Surface Energy to Flotation (Mineral Processing) - Froth flotation is the most commonly utilized method of separating valuable minerals from the associated gangue (waste) minerals found in an ore. In flotation, air is passed through an agitated mineral suspension, and hydrophobic particles attach to the bubbles, rise to the surface, and form a mineralized froth. This froth is recovered, and is the concentrate. However, the fundamentals behind the separation are still relatively poorly understood, with some hydrophilic gangue particles being recovered, and a proportion of the hydrophobic ones remaining in the suspension, to be disposed of as a tailings fraction. This project looks at the fundamentals of the surface chemistry of the mineral particles, and relates these characteristics to the flotation response of the minerals.
One of the most common methods of determining the wettability of a surface is to use contact angle measurements. However, the widely used method of determining the contact angle requires a perfectly flat surface with a droplet of liquid placed on the surface. The three phase angle that is formed is the contact angle. Limitations of this technique include the fact that in mineral processing, particles are separated, which do not have flat surfaces that can be measured in this way. To circumvent this, capillary rise methods have been utilized, relying on a liquid rising through a packed column of particles. This liquid rise is due to the Laplace pressure, and is related to the wetting characteristics of the liquid on the particle surface. The main difficulty is ensuring that the packing is consistent throughout all measurements made, which leads to differences due to different operators. Therefore, if another accurate method of determining the surface energy can be correlated to flotation, this will be of immense benefit.
The method of determining the surface energy in this project is inverse gas chromatography (iGC). Using iGC analysis, it is possible to probe the mineral particle surface directly, using molecular probes such as the alkanes. This analysis will give the components of the surface energy, the acid and base values of the surface, and from this a prediction of the flotation response can be made.
Gravity Concentration of Talc (Mineral Processing) - Gravity concentration is utilized to separate minerals of different density. It is widely used in gold processing, where the specific gravity of gold is significantly greater than that of the gangue minerals. Talc is one of the world’s most important industrial minerals. It is used in a wide range of areas, from fillers in plastics, to food. The value of the talc concentrate is related not only to the purity of the talc, but also in part to the colour – the whiter the product, the more valuable the product. Impurities that are found in talc deposits can be magnesite, or iron-bearing minerals such as hematite.
This project is aimed at removing iron impurities from a talc ore using gravity separation systems, such as Knelson concentrators and spiral concentrators. The talc sample will be from various points in the processing stream of an operating talc mine.
Microwave Processing of Minerals (Mineral Processing) - Recent estimates believe that crushing rocks (the comminution process) in the mining and mineral processing industries accounts for up to 6 % of the world's energy consumption. THis process is, unfortunately, as low as 3 % efficient. Microwave radiation has been touted as a method to reduce the energy requirements in the comminution process. This is due to the dielectric heating characteristics inducing fractures along grain boundaries.
It is also important to understand the effect of microwave radiation on the separation efficiency post exposure. Therefore, this project is two-fold: Determine the effect of microwave radiation on the comminution of a mineral ore; the effect of microwave radiation on the separation of the different minerals in the ore.
steve.yue [at] mcgill.ca (STEPHEN YUE)
Magnesium Alloy Solid State Processing - Magnesium, the lightest industrially significant metal, is being developed for automotive applications. Currently, there are very few applications for Mg sheet, primarily because of plasticity issues. These may be overcome by controlling the microstructure during hot working, which is the conventional means to produce Mg sheet from cast ingot. this work is to characterize the hot deformation behaviour of candidate Mg alloys.