Search Documents

By B. Grinbaum

The solvent extraction of Cu from acidic leach solutions is carried out using oxime extractants. The mechanism can be described as liquid ion exchange, where a labile H+ in the oxime replaces Cu++ ion from the pregnant leach solution. The process is reversible and, at high acidity, the copper is stripped back to the aqueous phase. As the extraction proceeds, the acidity of the aqueous phase increases and the equilibrium may shift against the extraction reaction. This phenomenon may become significant in leach solutions with high copper concentration, where large amounts of acid are transferred from the solvent into the aqueous phase. An efficient way to increase the recovery of copper consists of splitting the extraction into two circuits, and either neutralizing with lime or extracting the excess acid of the intermediate raffinate. In the second case, the acid can extracted using a solvent, which can be stripped with a base, e.g., NaOH or ammonia. A third option is direct neutralization with soluble basic salt, e.g., Na2CO3, within a single extraction battery. The choice of the preferred process depends on the specific process demands and on the relative availability and price of the raw materials and by-products price.

Jan 1, 2007

By J. H. Baek, D. W. Lee, B. K. Kim

Nanostructured Cu-Al203 composite powders were synthesized by thermochemical process for an electrode application. The synthesis procedures are 1) preparation of precursor powder by spray drying of solution made from copper and aluminum nitrates, 2) heat treatments to evaporate volatile components in the precursor powder and synthesis of nanostructured CuO+Al2O3, and 3) CuO reduction by hydrogen into Cu. The suggested procedures stimulated the formation of the gamma-Al2O3. The mean particle size of the final composite powders was 20nm, and the electrical conductivity and hardness in the hot-extruded bulk were competitive with Cu/Al2O3 composite by the conventional internal oxidation process.

Jan 1, 2004

By A. Cadieux, J. -B. Pineault, C. Allaire

The temperature measurement of the molten metal in the aluminum transformation process is of prime importance. This is particularly the case for aluminum treatment furnaces, such as holding and melting furnaces. Such reverberatory type of furnaces involve a thermal gradient across the metal line which limits the life of conventional thermocouple protective ceramic shields, due to the action of locally induced thermal stresses. This paper presents a novel thermocouple assembly using a composite refractory protective shield allowing long term resistance to such above conditions. Example of results obtained from various tests in aluminum holding furnaces are presented. The results confirm the superiority of the novel thermocouple assembly, as compared to conventional thermocouple units.

Jan 1, 2004

By Y. Turen, Y. Karakas, E. Candan, C. Sahinturk

In this study, wettability between sprayable tundish lining (MgO) and molten steel was investigated by using sessile drop method. Content of glass fiber (SiO2) in the MgO varied between 0 to 8 wt% whereas mean particle sizes of the MgO were 25, 75, 150 and 300µm. Experimental results revealed that contact angle (0) of sessile drop on the MgO was not altered by the addition of glass fiber up to 1 wt.% whereas above 2 wt.% addition decreased the 0 considerably. Contact angle, 0, increased considerably with increasing MgO particle size. SEM analysis showed deposition of glass phase was present at the interface as the finer MgO particles were used.

Jan 1, 2004

By Z. -G. Ren, J. -S. Qian, Y. -G. Yang

The waste slags from chemical and metallurgical plants contain approximately wt 1% water soluble Cr6+. This hexavalent chromium is very harmful to human health, and the treatment of the slags has concerned metallurgists for many years. A sintering method was developed to treat the waste slag. In this process, sinter was made from a mixture of the waste slag containing hexavalent chromium, iron concentrate and coke breezes. During sintering, hexavalent chromium was reduced to trivalent chromium. The latter is known as a non-harmful material and can be used as chromium resource for the production of ferrochromium or chromium-containing cast iron. After sintering the hexavalent chromium in the sinter could be reduced to less than 0.0008%. It was found that the waste slag with fine particles was favourable to the Cr6+ removal. An increase of carbon content in the sintering mixture could increase the rate of Cr6+ removal and the strength of the sinter produced. The rate of Cr6+ removal increased with increasing basicity of the sintering materials with basicity less than B=1.8, above which it decreased with increasing basicity. Blast furnace was found to operate smoothly when using the sinter made from the waste slag containing chromium. However the productivity of sintering machine was slightly low compared to the sintering operation using ordinary raw materials.

Jan 1, 2004

By Richard Dawson

Increasing global demand for coking coal has initiated several new coal mine developments in northeast BC. These developments are able to take advantage of the currently under utilized infrastructure that was put in place during the 1970?s and 1980?s for the Quintette and Bullmoose coal mines; which includes the Town of Tumbler Ridge, a 1,000km rail line to the coal terminal at Prince Rupert and a road system providing highway access to the town site. Coal within the two foothills regions of BC (north-east and south-east) is mined by open pit truck/shovel methods. Optimized mine plans require a thorough understanding of Rocky Mountain structural geology, attention for access in steep terrain, and a related understanding of the geotechnical conditions that control the stability of pit slopes and waste dumps. Thus there is a requirement to properly integrate mine planning with geotechnical engineering considerations. Many of the technical issues are well understood from experience during the past 30 years of Western Canadian coal mining. The challenge is to ensure that the mine plans are able to take full advantage of these lessons learned. The paper will focus on mine planning and geotechnical design issues to do with high angle-of-repose waste dumps and steeply bedded footwall slopes to illustrate the advantage of properly recognizing the important stability control issues during the early stages of engineering evaluations. Case histories from the existing and planned coal mining operations will be presented.

May 1, 2006

By M. Özer, F. Boylu, G. Önal

In this study, the fine coal waste subjected to the experiments is taken from the waste stockpile of Soma Coal Plant. The possibilities of its evaluation and the production of clean coal were investigated. For this purpose, Reichert Coal Spiral and Shaking Table are used. The minus 1 mm coal waste includes 60.43% ash and 50% minus 38 micron material by weight. The microscopic observations of the screen fractions were shown that the clay minerals are in fine sizes and the coarser size fractions contain silica and carbonate minerals as ash forming materials. The tests were conducted after desliming. The commercial grade clean coal product containing 29-35% ash with a calorific value of 3800-4200 kcal/kg (15.91-17.58 MJ/kg) was obtained by gravity methods.

Jan 1, 2004

By K. Shitogiden, Y. Samada, T. Miki

Steelmaking slag contains nutrition such as Si, P and Fe for acceleration of phytoplankton growth. Phytoplankton can fixate carbon dioxide more than any other species on earth. Hence, suppression of CO2 can be achieved by applying the potential of steelmaking slag as the nutrition for their propagation. When it is considered to supply nutrition from steelmaking slag to seawater, we must avoid dissolution of hazardous elements or change of pH of seawater by steelmaking slag addition into seawater. The protection against dissolution of fluorine into artificial seawater has been studied based on dissolution behavior of steelmaking slag and synthesized substances into artificial seawater in the present work. The dissolution mechanism of fluorine from steelmaking slag and buffering action of pH change are discussed by using stability diagram in seawater.

Jan 1, 2004

By S. Kamado

Development of new SF6 alternative cover gas with low global warming potential is strongly desired for melting and casting of magnesium alloys. We have tried to apply several kinds of HFC and HFE gases with low potential from 30 to 950 as protection gases to AZ91D alloy melt in the temperature range of 650 to 800°C. As a result, protective film consisted of MgF2 and MgO is formed on the melt surface and ignition-proof effect is sufficiently obtained at all the temperature ranges even when flow rates of mixed gases containing CO2 as a carrier gas are almost the same as those using SF6 gas. Reduction of global warming potential exceeds 98% at 650°C and 89% at 800°C in comparison with a mixed gas of CO2 and SF6.

Jan 1, 2006

By N. Verbaan, Ph. Henry, S. Lamotte

Hydrometal(lurgy) provides an adequate technology to reintroduce otherwise lost metal units into the industrial cycle, thereby saving resources and energy, while keeping the environment cleaner. Three case studies at an integrated hydrometallurgical recycling facility (Hydrométal) in Belgium are discussed. (1) Non-ferrous leach residues are treated by a leach-SX process to recover their minor metals (Ge) contents. The remaining acid waste solution is used by the fertilizer industry nearby. (2) Residual low quality acid and caustic are used in the processing of zinc industry cements to produce copper, nickel, cobalt and zinc concentrates by several consecutive selective leach - precipitation processes. (3) Copper anode slimes are treated and their precious metal contents are recovered. Depending on the composition of the slimes, separate or combined concentrates of copper, bismuth, tellurium/selenium and silver/precious metals can be produced.

Jan 1, 2004

By Raj Thamburaj, Li. Ping, Prakash C. Patnaik

"An effective prognosis system for aircraft engines may involve the application of a wide range of technologies and methodologies, which may include: - On-line, real-time and in-situ non-destructive inspection/detection/sensoring - Aircraft/engine instrumentation - Airborne data recording system - Advanced signal filtration - Data compression technologies - On-line engine health monitoring technologies - On-line engine component life usage monitoring technologies - Mission severity analysis algorithm based on life prediction and damage tolerance analysis models - Life assessment methodologies - Optimized repair/overhaul/maintenance planning - Optimization of mission assignment and homogeneous life usage - Web-enabled information delivery and sharing system - Decision making logistics This paper will demonstrate some efforts that Orenda has accomplished over the last decade in collaboration with the Institute for Aerospace Research of National Research Council Canada and the Department of National Defense. The presentation will focus on the following projects:"

Jan 1, 2004

By T. H. Etsell, P. C. Holloway

The fly ash produced by oil sands operations in northern Alberta represents a large, high-grade, potential resource for vanadium production in Canada. After extensive batch testing at the University of Alberta, a conceptual process flowsheet for the recovery of vanadium from oil sands fly ash has been developed. The various unit operations for this process, including decarbonization, roasting, leaching, desilication, precipitation, salt recovery and byproduct recovery, are described. Processes for the recovery of molybdenum and ammonium chloride from waste streams from this process, are proposed, as are potential uses for the ash residue; these byproducts represent significant potential sources of secondary revenue while reducing the environmental impact from the process. A preliminary economic analysis for vanadium recovery from oil sands fly ash using this process is also included and several major economic factors influencing its commercialization are discussed.

Jan 1, 2004

By Sergio Bustos

A significant expansion project is under way at KATCO?s Torkuduk In Situ Leaching (ISL) operation to increase uranium production up to about 4000 tU/year. Higher flows and lower uranium concentration are expected in the rich solutions coming from the well fields. Therefore, extra adsorption and elution columns and modified operating conditions are required to deal with the increased demand for uranium transfer from the ISL solutions to the eluate solution, which goes to the uranium precipitation section. Resin adsorption and elution performance have been interpreted and projected by using Mac Cabe-Thiele equilibrium diagrams. The resin load, the adsorption mass transfer coefficient, the adsorption zone height and the eluate concentration have been estimated for the expected changing operating conditions associated to the future mine plan. This information has allowed to improve the present operation results and to define the main process design criteria for the expansion project.

Aug 1, 2010

By Y. Vermeulen, J. Simoes, P. Guillo, A. Di Donate

New design techniques have been developed to optimize continuous casting (CC) refractory components. The overall objective is to increase CC productivity as well as steel quality by using optimized refractory from tundish-to-mold. These techniques allow the prediction of steel and refractory chemical interactions and, thus, steel chemistry evolution as well as build up and corrosion occurrence. Specific fluido-dynamic models (CFD) have also been developed to better take into account the physical parameters at the steel/refractory interface and to optimize steel flow control. The CFD model can be coupled with refractory chemical interactions to simulate steel chemical evolution. These two different approaches result in shape and material modifications. They are completed by dedicated thermal stress analysis in order to improve thermal shock resistance. The mechanical FEA evaluations take into account specific mechanical behavior of refractory components as well as high temperature evolution of their properties.

Jan 1, 2004

By Xiao Huang, Jean-Francois Thibault, Ali Merati, Prakash C. Patnaik

Single-crystal nickel-based superalloys are the current state-of-the-art technology for the manufacture of turbine blades. This technological improvement of the turbine blade has brought a considerable increase in its cost. Repair and overhaul of service stressed single crystal turbine components is an economic necessity for life cycle cost reduction of engines since the cost associated with replacement is significantly higher than its counterpart polycrystalline component. This paper will first review the recently reported research in developing repair technologies used for DS and SX components. These techniques repair the crack or defect while at the same time ensuring that the mechanical properties do not deteriorate and, more importantly, that the single-crystal microstructure is not jeopardized. It will then be followed by a brief overview of the research conducted and initiated by the authors with regards to the repair of single crystal alloys.

Jan 1, 2004

By R. A. Mantz, V. N. Balbyshev, A. N. Khramov, N. N. Voevodin

Corrosion protection properties of the hybrid organo-silicate coatings on aluminum substrate can be significantly improved by means of encapsulation of organic corrosion inhibitors within the coating material. In order to achieve sustained release of corrosion inhibitor and long-term corrosion protection, a secondary chemical equilibrium of either ion-exchange interaction with the coating matrix or cyclodextrin-assisted molecular encapsulation of the inhibitor has been employed. Several organic corrosion inhibitors, such as mercaptobenzothiazole, mercaptobenzimidazole, mercaptobenzimi¬dazolesulfonate, and thiosalicylic acid have been examined by a group of electrochemical methods including potentiodynamic scan, electrochemical impedance spectroscopy, and scanning vibrating electrode technique. It has been found that the formulations that contain ß-cyclodextrin demonstrate superior corrosion protection capabilities as the complexation equilibrium results in a continuing delivery of inhibitor to corrosion sites. The approach is considered a promising way for active corrosion protection of high-strength aluminum alloys when integrity of barrier coating is compromised.

Jan 1, 2004

By D. D. Rodier

The mining and metals indusrty's approach to Sustainable Development has dramatically evolved in response to growing concerns for the future ability of the industry to continue as a vital contributor to the sustainability of society. This paper will review recent trends,including the overriding global issues impacting the sustainability of society and what the Global responses to these issues have been. This will be followed by the response of the mining and metals industry to better contribute to sustainable development, starting with the landmark independent study the MMSD Study and the creation of a global policy voice for the industry, the Intrenational Council for Mining and Metals (ICMM). The tenants of the ICMM's Sustainability Framework guide this organization's work with the overall themes of performance improvement, leadership and leverage through partnerships. The paper will then conclude with a brief description of an example of what, an individual company, a service provider to the industry, is doing to assist in the industry's efforts.

Jan 1, 2007

By J. Beddoes

The various microstructural factors that influence the creep resistance of y-titanium aluminides are presented and discussed. Titanium aluminides have potential for a variety of intermediate temperature applications in both gas turbine and reciprocating engines. While it is well established that the 'fully lamellar' titanium aluminide microstructure offers superior creep properties, the particular influence of lamellar morphology, third phase precipitation, and grain boundary structure in controlling both the primary and tertiary creep behaviour is presented. The results are primarily based on tensile creep experiments undertaken using several titanium aluminide intermetallic compositions processed via powder metallurgical techniques, investment casting and Bridgman directional solidification. The results indicate that lamellar structure and precipitate formation have a major impact on primary creep, while microstructural degradation through both lamellar and precipitate coarsening influence on the onset of tertiary creep leading to fracture. The results are used to design a creep resistant microstructure produced by directional solidification and the effectiveness of this designed microstructure is demonstrated through 10,000 hour creep tests.

Jan 1, 2004

By T. Nagasaka, T. Miki

Suppression of CO2 and waste such as slags discharged from iron- and steelmaking processes are some of the typical major issues for the protection of global environment and sustainable growth of steelmaking industry. Utilization of active phytoplankton growth will be one of the best options to stabilize and suppress carbon dioxide at high-efficiency. Inorganic minerals such as C, 0, N, Si, P and Fe are necessary for phytoplankton multiplication. It is crucial for supply of nutrition into seawater effectively for phytoplankton multiplication to understand the dissolution behavior of some elements from steelmaking slags into seawater. The morphology of the precipitated phases in steelmaking slags during cooling period was investigated in the present work. The dissolution behavior of some elements from steelmaking slags into artificial seawater has also been studied. The effect of nutrient dissolved into seawater on phytoplankton multiplication, some examples of marine structure made from steelmaking slag, and estimation of CO2 fixation amount by marine phytoplankton are also discussed.

Jan 1, 2004

By N. Ntakaburimvo, C. Allaire

This paper presents an innovative experimental set-up which simulates refractory degradation by separate and simultaneous action of abrasion, erosion and partially or totally immersion corrosion whether dynamic or static. It also presents abrasion testing results obtained from five commercial aluminosilicate refractories used in aluminium melting and holding furnaces. Abrasion wear was quantified by measuring the weight loss and the depth of wear, as well as by determining materials properties degradation, such as the residual rupture force and the residual modulus of rupture. Results were correlated to as- fired materials properties, such as rupture force, flexural strength, elastic modulus, toughness, and apparent porosity; in order to establish which property could be used for refractory abrasion wear prediction. They were also related to the critical length of pre-existing defects and to those generated by the abrasion process. Positive correlation was established between abrasion resistance and mechanical properties, particularly for refractory castables. For similar mechanical strength, the castables tested offered less abrasion resistance than the brick sample.

Jan 1, 2004