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By Q. Jia, M. Rigaud, F. Ye, X. Zhong

In this work, the rheological behavior of ultra-low cement alumina-based castables with addition of flake graphite and extruded graphite pellets has been investigated. Emphasis has been laid on the influence of the type and amount of carbon additions and the results are compared with corresponding alumina castable samples without any carbon addition. It is found that alumina-based castables with extruded graphite pellets have good rheological behavior and flowability with lower water demand (< 6.3%), and no segregation during the shearing of castable.

Jan 1, 2004

By I. Zhitomirsky, X. Pang

The outstanding thermal and chemical stability, excellent mechanical properties and biocompatibility of zirconia have made this material an important candidate for fabrication of advanced protective coatings on metals, graphite, carbon fibers and biomedical implants. Nanostructured polymer-ceramic composite films containing zirconia were synthesized on metallic substrates by combining cathodic electrosynthesis of inorganic particles with electrophoretic deposition of cationic polyelectrolytes. Thick crack-free oxide and composite coatings were obtained using this newly developed technique. The deposits were studied by thermogravimetric analysis, X-ray diffraction analysis, scanning electron microscopy and atomic force microscopy. The mechanisms of deposition are discussed.

Jan 1, 2004

By Y. Qi

A cell-level nonlinear dynamic model of solid oxide fuel cell (SOFC) based on physical diffusion principles is built in this note. It demonstrates that reactant diffusion processes from gas flow bulks to triple phase boundaries (tpbs) play an important role in the dynamic behaviors of SOFC. The simulation shows that under certain condition, the effect of the double layer capacitance may be neglected. The phenomenon of slow rise of voltage in current interrupt experiment may be explained by the dynamic behaviors of partial pressures in the vicinity immediately above tpbs.

Jan 1, 2005

World copper electrowinning tankhouse plant practices have been surveyed. This survey is a supplement to previous surveys that have been carried out in 1995, 1999, 2001, 2002 and 2003. On a world basis, process technology trends include the further installation of automated electrode handling systems including permanent cathode systems, automated cathode handling machines, fully automatic cranes and polymer concrete cells. Designs also have included larger electrode sizes and higher electrolyte flows and current densities. Overall these trends have further resulted in optimized tank house productivities and improved electrowon cathode purity. Most greenfield copper electrowinning projects are occurring in South America and Central Africa.

Jan 1, 2007

By K. Konigsman

"Representatives of various industries and the Canadian coast Guard formed a Bulk Cargoes Committee three years ago. In 1976 and 1978, I have attended the meeting which take place once per year here in Ottawa as representative of the Canadian Mineral Processors, Dave Hendricks from Granisle accepted the charge in 1977. Our Secretary, Bob Bruce, has suggested repeatedly that I report to the Membership on the deliberations to this group. Twice I found good excuses; this year I did not. I was reluctant to address you since the Committee's deliberation proceeded at a pace which might be identified as Government squared. The Committee advises a Government agency which in turn negotiates with foreign Government agencies.At the outset, I will describe the developments which led to the formation of the Committee and its purpose.The Canadian Mining Industry ships annually millions of tons of products to overseas customers; be it iron ore, coal, fertilizer, or base metal concentrates. Most loadings are in vessels of foreign registry and all will be directly affected by Canadian or International regulations of the transport of such bulk commodities. The major shipping nations are members of an Intergovernmental Maritime Consultative Organization (IMCO). This organization elaborates regulations which govern shipment of all cargo, bulk materials and concentrates included. At IMCO'S deliberations, Canada has one vote, one voice on the Consultative Committee and is represented by our Coast Guard. The Coast Guard has over the years been in contact with industries when discussions concerned shipment of bulk cargoes. In the early sixties, a ""Concentrate Committee"" did exist. It consisted of metallurgists from a number of mining companies and Government representatives. This committee was instrumental in the development of what became known as the ""Concentrate Code"", legislation which has evolved into the Canadian Bulk Cargoes Code as it is known today. The concepts of the flow moisture point and transportable moisture limit originated from its work. Incidentally, both criteria are widely accepted and utilized world-wide. The Concentrate Committee faded away once the Concentrate Code has been adopted."

Jan 1, 1979

By H. P{ops

This paper summarizes important developments that have occurred in the mining and subsequent production of copper into rod and wire from 9000 B.C. until the present time. Principles and practices associated with continuous rod production are discussed from a metallurgical perspective, and include the effects of oxygen content and impurities. A brief historical review is also given of important wire drawing events dating back thousands of years. Finally, predictions concerning the future of the wire and cable industry are presented with particular emphasis upon copper wire, technology in this market, and competitive materials.

Jan 1, 2007

By Juan Pablo Vielma

In this work we study how to incorporate risk control to the generation of ultimate pits when orebodies are modeled through a finite number of conditional simulations. To control risk we consider a chance constraint on the value of the ultimate pit. We incorporate this measure into the generation of ultimate pits by solving a stochastic programming version of the ultimate pit problem. We compare this stochastic programming problem to previous approaches such as generating the ultimate pit for each simulation and the hybrid pit approach introduced by Whittle and Bozorgebrahimi. We also study the effect of using different number of simulations in the generation and evaluation of ultimate pits.

Oct 1, 2009

By M. Rigaud, K. Sankaranarayanane, X. Zhou

The effect of varying fine alumina/ultra-fine alumina ratio on the Bingham to dilatancy transition in alumina based, self-flowing refractory castables has been studied in detail employing rheological tests and particle size distribution measurements. Analysis of flow resistance and torque viscosity values has shown that Bingham to dilatancy transition is strongly influenced by fine alumina/ultra-fine alumina ratio in the castable, as well as by the nature of ultra-fine alumina. The calculated values of rheological constants and the viscosity coefficient were found to increase at higher fine alumina/ultra-fine alumina ratios.

Jan 1, 2004

By G. Ladouceur

"LOCATIONThe mine and mill are located in Lemoine township which is 20 miles directly south-east of the town of Chibougamau Quebec. Personnel live in Chibougamau and commute to the property over 33 miles of paved and gravel roads. Concentrates are trucked 13 miles to a railway siding on the line connecting Chibougamau and Quebec city.HISTORY Several companies explored the property before acquisition by Patino Mines (Quebec) Limited in 1973. Further exploration led to the discovery of a high grade copper-zinc orebody and the property was brought into production by the above company in 1976.ORE The ore contains 85% - 95% sulphides consisting of chalcopyrite, sphalerite, pyrite, pyrrhotite and minor gold and silver. Argenti tetrahedrite, antimonial silver, native bismuth and galena are also pre sent in very minor quantities. Associated gangue minerals are quartz, carbonates and occasionally chlorite."

Jan 1, 1979

By M. J. Hadianfard

The effect of holding at temperature on fatigue life of a 10 vol% particulate SiC reinforced Titanium alloy has been investigated. The influence of holding time at 600°C on fatigue of this material has been studied by using tension-compression tests, scanning electron microscope and image analysis. The specimens were heated to 600°C by using a controlled atmosphere furnace; hold at this temperature for time ranging from 0 to 100 hours, and then fatigue tested at room temperature under controlled constant plastic strain. The number of cycle to failure found to decrease with increasing of the holding time. In addition the fracture mechanism and number of debonded particles has been significantly influenced by holding time at 600°C.

Jan 1, 2004

By E. Paransky, M. Rigaud, G. Paschek, S. Palco

Some of the negative impacts of carbon addition on the strength of castables are yet to be overcome in order to fulfill its potential benefits for oxidation resistance. This paper reports the results of recent studies conducted at CIREP on the effects of different types of carbon additives on the thermo-mechanical properties of magnesia-based castables. Experimental techniques included measurements of the hot modulus of rupture (HMOR), hot modulus of elasticity (HMOE), as well as the wedge-splitting test (WST). The comparison of evolving microstructures was carried out employing scanning electron microscopy with microanalysis attachment (SEM/EDS) and X-ray diffraction (XRD). HMOR values of 12 MPa at 1300°C have been reached in MgO-Si02-C castables containing up to 7% carbon.

Jan 1, 2004

By L. Treadgold

The KOV, Kananga and Tilwezembe copper-cobalt deposits in the Democratic Republic of the Congo have lain dormant for over ten years due to lack of funding by the State-owned mining company, Gecamines. Nikanor Pic through its operating company DCP has secured the mining titles from the DRC government and has commenced redevelopment of these large copper deposits. DCP plans to produce 250,000 tonnes per annum of LME Grade "A" copper cathode and up to 30,000 tonnes per annum of cobalt salts. This paper describes the geology, re-development of the KOV mine and the two smaller mines, Kananga and Tilwezembe, the design of a new copper-cobalt processing facility and the challenges in refurbishing the associated infrastructure.

Jan 1, 2007

By D. Allen

Faced with decreasing ore grades and harder ores, many mines today are forced to become more efficient with their approach to processing. Variability in ore hardness, mineral liberation, reagent consumption, sliming, and leach responses are all a function of the minerals present and their concentration. Modern semi-automated X-ray Diffraction (XRD) analyses using Rietveld refinement techniques, in conjunction with high speed quantitative Near Infrared (NIR) analyses, provide reliable quantitative mineralogical ore profiling. By the implementation of XRD with NIR, mining, milling and leaching operations no longer need to be dependant on visual estimates for GeoMetallurgical Modeling and are provided with a valuable forecasting and production control tool. This paper will illustrate the development, plant implementation and application of XRD and NIR at several copper operations.

Jan 1, 2007

By C. Sorel

The solvent extraction systems devoted to uranium purification from crude ore to spent fuel involve concentrated solutions in which deviation from ideality can not be neglected. The Simple Solution Concept based on the behaviour of isopiestic solutions has been applied to quantify activity coefficients of metals and acids in the aqueous phase in equilibrium with the solvent. This approach has been validated on various solvent extraction systems such as trialkylphosphates, malonamides or acidic extracting agents both on batch experiments and counter-current flowsheets. Moreover, this concept has been successfully used to estimate the aqueous density which is useful to quantify the variation of volume and to assess criticality parameters such as number density of nuclides.

Aug 1, 2010

By R. Ham-Su, J. P. Healey, S. P. Farrell, R. S. Underhill, M. A. Gharghouri, C. V. Hyatt, L. M. Cheng

Magnetic shape memory alloys (MSMA&apos;s) are a class of materials where magnetic energy can be converted into mechanical energy and vice versa. NiMnGa-based MSMA&apos;s have attained magnetic field induced strains up to approximately 10% and have a relatively wide operating temperature range, from well below 0°C to above RT, making them very attractive for a variety of applications. However, these materials also suffer from low toughness. Using these materials in a composite could mitigate this shortcoming, and also overcome limits imposed by inertia and eddy current losses. In this work, we describe the manufacture and characterization of such composites. Composites with 30% by volume MSMA were fabricated under a magnetic field resulting in anisotropic magnetic properties. Damping properties were evaluated by dynamic mechanical analysis.

Jan 1, 2004

By M. Solomon

Abstract -Giant, sediment-hosted lead-zinc deposits in northern Australia formed during development of Mid-Proterozoic extensional basins that overlie Lower Proterozoic basement. The basement in the Mount Isa area, exposed by folding and faulting, contains fractionated, high-heat-producing granites. These granites generate heat at a rate of about 6 ?Wm-3, probably sufficient to form giant lead-zinc deposits either by (a) driving episodic convection of saline basement and basin fluids for periods of 105 to 106 years at temperatures of about 230°C, or (b) heating basin fluids moving under the influence of topographic relief or fault movement. The presence or absence of such granites may form a vital component of the genetic model. Ore-forming fluid flow was probably initiated by continent-scale, extensional basin fracturing.

Jan 1, 1992

By M. S. Moats

As smelter feeds become more complex, the impurities that ultimately report to electrorefineries are changing. Many of these impurities collect in the electrolyte and must be controlled. As commercial copper electrorefineries look to expand their capacities by increasing their operating current density, the interaction between electrolyte composition and anode passivation can cause operational difficulties. To improve the industry&apos;s understanding of the passivation phenomena, the role of electrolyte composition was evaluated using commercial electrorefining anode samples. The electrolyte composition variables examined were copper, acid, nickel, arsenic, chloride, thiourea and glue. Finally, the role of non-commercially utilized additives, such as bromide and polyethylene glycol were studied. From this investigation, electrolyte parameters that inhibit copper dissolution through copper sulfate precipitation, copper oxide stabilization and/or absorbed species lead to accelerated passivation. Species that prevent passivation have the ability to complex cuprous ions. Possible mechanisms for the role of each.

Jan 1, 2007

By Z. Mubarok

An overview of the problems encountered the electrorefining of copper anodes containing high levels of nickel and antimony is presented. Our investigations have been focusing on the passivation behaviour of the anodes with high contents of Ni, Sb, Sn, and Pb, the formations of kupferglimmer and floating slimes. The results of linear voltammetry, chronopotentiometry and electrolysis test revealed a noticeable lower resistance of the anodes to passivation in comparison to those with lower contents of Ni, Sb, Sn, and Pb. Anode containing kupferglimmer exhibited oxygen gas evolution during the passivation state. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) indicated that tin can replace and/or join antimony in the kupferglimmer structure. Under specified experimental conditions, floating slimes precipitations took place with high Ni, Sb, Sn, and Pb anodes prior to the end of one anode period.

Jan 1, 2007

By T. Watanabe, M. Nakagawa, K. Kimapong

Ultrasonic wave was irradiated on metal surface in water to introduce compressive residual stress. The ultrasonic wave that was oscillated with 19.5 kHz ultrasonic transducer and amplified with a step type horn was irradiated. Slight plastic deformation occurred at the surface region of pure metal such as Cu and compressive residual stress was introduced. It seemed that the plastically deformed depth from the metal surface corresponded approximately to the depth of introduced residual stress. The higher compressive residual stress could be introduced into the surface of Cu-Zn brass and SUS304 stainless steel because work-hardening was simultaneously induced to those alloys. Furthermore, since martensitic transformation was induced by the plastic deformation in the case of SUS304, the compressive residual stress could be introduced more deeply into the surface region. The residual stress of SUS304 reached to the maximum value of 574 MPa by irradiating for 5min.

Jan 1, 2004

By G. C. Weatherly, D. S. Wilkinson, A. M. Limarga

In addition to the harsh environment, materials for high-temperature applications are often subjected to a significant mechanical loading. Several researchers have noted that the rate of oxidation can be affected by stress in a range of materials. We have recently studied this effect in y-TiAl, based on the preliminary work of Magnan and Weatherly which showed that nitridation rates on the tensile side of a flexural creep specimen could be 10 times higher than on the compressive side. We have since developed a four-point bending creep setup capable of controlled atmosphere testing. We present quantitative data on the effect of creep on scale growth under a range of atmospheric conditions. Finite element analysis will also be used to show how modest applied stresses can have a large effect on scale growth rates through the generation of large stresses due to the mismatch of creep rate between the metallic substrate and the scale.

Jan 1, 2004