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By A. Rosenfeld

The feasibility of applying laser induced optical emission spectroscopy to the high speed sorting of mixed alloy aluminum scrap is investigated. The basic spectroscopy for analysing aluminum alloys for the major alloying elements over their full concentration ranges is established. Materials handling issues are also described and the components of an overall sorting system are presented.

Jan 1, 1995

By M. M. Kim

Zn-27% Al was pressure infiltrated into a column of 20 micron diameter abrasive grade SiC particles to give billets with particle loading of 50 voli.une %. Some billets were heated to a temperature where they became semi-solid and diluted with liquid Zn-27% Al alloy to give billets with particle loadings of 12 and 16 volume %. Some of these billets were then extruded into wire with an area reduction of approximately 98%. Tensile properties of the as-cast billets were always inferior to those of the matrix alloys; however, the extruded composite samples showed at 37% improvement in ultimate tensile strength compared to their extruded conventional counterparts. The fracture surfaces of these samples are described.

Jan 1, 1990

By François Tremblay

It is well known that removal of organic material such ,as Jacquer, paint, plastic prior to melting improves aluminum recovery. In addition to being an important economically, decoating of aluminum scrap has a positive impact on the environment, through better control of gaseous emissions. Most of the existing thermal decoaters for aluminum have been designed to operate with scrap containing a level of organic material lower than 10%. The main field of their present application is for recycling of used aluminum can, where levels of organic material are lower than 4%. Alcan has recently developed a new thermal decoating system in order to extend applications of this process to a much wider variety of aluminum scrap. The new decoater efficiently processes aluminum scrap with a level of organic material up to 50%. This new technology features the use of fluidized bed technology to thermally control the process. This innovative feature improves both performance and control over conventional delacquering systems based on hot air convection. This paper describes the basic principles of the technology and the design of the? first industrial unit commissioned by the Alcan Recycling plant in Shelbyville (TN) at the beginning of 1994. Typical applications and operating advantages are discussed.

Jan 1, 1995

By Eleazar Salinas R., Miguel Perez L., J. Cesar Juarez T., Martin Reyes P., Eduardo Cerecedo S., Isauro Rivera L., Francisco Patino C., Juan Hernández A.

"A complete characterization of burrows from Mining district of Pachuca - Real del Monte, in Hidalgo state Mexico, was done. These kind of residues had not been formally characterized, founding an average chemical composition of 70.43 % wt. of Si02, 7.032 % wt. of Ah03, 2.69 % wt. of Fe20 3, 0.70 % wt. of Mn, 3.98 % wt. ofK20, 3.34 % wt. of CaO, 2.50 % wt. ofNa20, 1.01 % wt. of MgO, 0.26 % wt. of Ti02, 0.04 % wt. of Zn, 0.026 % wt. of Pb, 56 g/ton of Ag and 0.6 g/ton of Au; In the same way, the residues present as majority mineralogical phases the following: Quartz, Berlinite, Orthoclase, Feldspar, Anorthoclase and Calcite. By the other hand, joint with the big volume that present these residues and the chemical and mineralogical characteristics, these materials or sub - products can be used for production of ceramics, into mixes forming some materials for architecture (bricks, blocks, and tiles), refractory bricks, in the production of cement and to get some metallic values such as gold and silver involved in these residues.IntroductionActually the mining residues in Hidalgo State, Mexico are the result of more tan 500 years of mining, leading so a great volume of deposits, which we can classify in different types, among the most communes we have: Acid Mining Waters, Waters of solid transport and elements in the form of radicals, deposits of abandoned minerals without processing, and mining wastes of processed minerals known as burrows or dumps, being these the most abundant in the Hidalgo State [1-4].Form the metallurgical point of view, it is known that a characterization study if fundamental to find the viability of reuse of these kind of residues, leading so an additional use and the opportunity of get an alternative use into several industrial processes, due to its contents of oxides of silicon, iron, aluminum, calcium, sodium and potassium, principally, besides of its mineralogy and distribution of chemical elements into its primary and secondary phases [ 1-2, 5- 6]."

Jan 1, 2011

By Bin Du

In recent years, concurrent product design and process is gaining popularity and will become a norm of the industry of the future. Forging has been a critical manufacturing process for production of components with superior tensile strength, toughness and grain flow. This paper describes an expen system which is being developed for forging die design and forging process analysis in concurrent engineering environment. Rules and guidelines pertaining to forgeability are formulated and incorporated into the knowledge-base in building the system. The system is built using an object-oriented paradigm. The object-oriented approach and hierarchical rule structure paradigm are briefly discussed. Finite element analysis packages (ALPID-2D) were incorporated into the program to give the simulation result of the forging process. The system can automatically produce a competent design and recommend a set of processing parameters for a given product. The designer can modify the design according to the result of the simulation.

Jan 1, 1992

By Sylwia Zymankowska-Kumon, Rafal Danko, Mariusz Holtzer, Artur Bobrowski, Michal Kubecki

"Moulding sands with furan resin constitute constantly growing part in technologies of producing castings from iron alloys. Due to the presence of harmful substances in resins such as furfuryl alcohol, phenol and formaldehyde, using those mould sands may be hazardous to the natural environment and workers. The general assessment of harmfulness of sands used for molds and cores encompasses 2 basic points: emission of hazardous substances during processes of preparing sands, pouring mold with liquid metals (high temperatures), cooling and shaking-out; possibility of washing out hazardous substances from used sands to the environment, during storage or economic use outside foundries. We present the results of research on the assessment of harmfulness of mould sands with furan resin in the scope of the above points. The research was conducted according to the original method prepared by the authors, which has been used for years in cooperation with various foundries (Poland, abroad).IntroductionSands are used by the foundry industry to create metalcasting moulds, where the individual sand grains are typically bound using bentonite clay and carbonaceous additives or resins. During the casting process, the moulds can be exposed to temperatures as high as 1500°C depending upon the metal being poured. The molten metal causes thermal decomposition of carbonaceous additives or resins, which results in the formation of potentially hazardous organics that are emitted to the atmosphere and condense in the moulding sand [1]. The moulding sands are reclaimed within the foundry, but part of them are eventually discarded in landfills, because it is not longer suitable to make metalcasting molds [2, 3]."

Jan 1, 2013

By Alberto Oalvez, Lucya Yunus, Pengfii Tan

"Laboratory flotation tests of slow cooled converter slag have showed that 92.5% copper recovery at the copper cut-off grade of 24 - 25 % can be achieved by using a 50:50 ratio of DSP330 and SIBX (sodium isobutyl xanthate) at the natural pH of 7 and with a grinding time of 18.5 minutes. 70ìéç is the P80 achieved at this grinding time. MIBC is the frother and the solid content of the flotation feed was 46%. In the plant trials, two types of collectors at two different feed particle sizes for both the normal and slow cooled slag were operated. The particle size was controlled by the feed rate. The P80 of 75 ìçé at a feed rate between 32 - 36 t/h were tested. The plant trials have demonstrated that the copper recovery in the milling and flotation process of the slow cooled slags was improved by 3%. IntroductionIt is proposed to float the slow cooled converter slag, in the auxiliary circuit of the copper concentrator at Mount Isa, by using the processing conditions identified from several laboratory flotation tests. Among these laboratory tests, one produced a copper recovery of 4 % higher than those achieved from a normal cooled slag with the same slag feed grade and the same copper content (24 - 26 %) in the concentrate. These test conditions were selected for further studies.Laboratory Test Work and Plant TrialsThere has been a lot of work conducted under laboratory and plant conditions [1]. However, the achieved results did not justify their total implementation in the Mount Isa Copper Concentrator. Initially, the lab trials were carried out with slag cooled 100% in air; then it was changed to combined cooling for 12 h with air and 2.5 days with water sprays. The reason for this change was the shortage of space when the slag was cooled 100% in air, as it takes several days to achieve safe temperatures for its removal. The San Manuel Copper Smelter has reported that their slag was left for air cooling in pits for 8 h and then was followed by water cooling for 2-3 days [2]"

Jan 1, 2012

By D. P. Cook, M. I. Bloch, J. A. Dantzig

"In this article, we describe a combined experimental and computational program to study the filling of automotive wheels during low pressure die casting. Experiments are performed by placing thermocouples into the mold walls of a production caster for the Ford F 113 wheel to measure the temperature profiles in the die during processing, and to infer the filling pattern. Computational models are also developed using a 36° section of the wheel pattern, taken directly from CAD data files. We use these models to simulate the filling and heat transfer processes. Comparison between experimental and computational results are presented, demonstrating the viability of this procedure.IntroductionAutomotive companies are using increasing amounts of aluminum in production vehicles: While the main driving force is improved fuel economy through weight reduction, replacing steel wheels by aluminum also offers the potential for improved vehicle performance by reducing unsprung mass. For these reasons, many new vehicles are now supplied with cast aluminum alloy wheels, and the aftermarket for these wheels continues to grow.The most common production process for these wheels is low pressure die casting. The process is subject to numerous defects, including microporosity, cold shuts, cold folds, misruns and inclusions. Scrap rates at the caster of the order of 10% are not uncommon. Many wheels also have large production runs, into the hundreds of thousands of wheels per year. Thus, the cost savings from even small reductions in scrap rate have the potential to be quite significant.Most of the defects are associated with the filling and solidification processes in the mold. The molds are air cooled, and the placement and sizing of cooling passages is currently as much art as science. The ultimate goal of this project is to improve that situation, by implementing simulation procedures that enable engineering design methods to be used in die and process specification."

Jan 1, 2000

By E. Fockedey

he destruction of free cyanide on a Co3O4 doped carbon felt was studied. The experiments were done with an eiectrochemical filter press cell on dilute alkaline solutions containing 250 mg/l NaCN. No chloride ions were added to the solutions. The cobalt oxide protects the felt against corrosion and has a catalytic effect on the degradation of the cyanide. This kind of electrode allows working with current density as high as 1200 Aim without any visible degradation of the felt. The most interesting results were obtained with a current density of 400 Aim' at which the cyanide concentration can be lowered to 5 mg/l with a current efficiency of more than 70 % and a specific energy consumption of about 10 kWh/ kg CN.

Jan 1, 1998

By I. Gaballah

The kinetics of oxychlorination of pure CI-2O3 with C12+02 gas mixtures is studied by ThermoGravimetric Analysis (TGA) in non and isothermal conditions up to 1000 °C. The reaction of Cr2O3 with C12+O2 chlorination gas mixtures starts at about 550 °C and the reaction product is CrO2Cl2. The oxychlorination rate of Cr2O3 is almost proportional to the chlorine partial pressure and to the fourth root of the oxygen partial pressure in the chlorinating gas mixtures. At 800 °C, the maximum chlorination rate is obtained using a gas mixture having a C12/O2 ratio equal to 4. The apparent activation energy of the oxychlorination reaction of Cr2O3 is 87 and 46 kJ/mol at temperatures lower and higher than 650 °C, respectively. By varying the chlorine and the oxygen partial pressures of the oxychlorinating gas mixtures at temperatures higher than 550 °C, it is possible to extract selectively the chromium chlorinated compounds from the chromium bearing materials. a. Laboratoire Environnemem et Minéralurgie, BP 40, 54501 Vandceuvre, France, b. École Nationale Supérieure de Géologie, Rue du Doyen Marcel Rouhault, 54501 Vandoeuvre Cedex, France, c. Centre National de la Recherche Scientifique, 3 rue Michel - Ange, 75794 Paris Cedex, France, d. Insritut National Polytechnigne do Lorraine, Rue de la Font de Haye. 54501 Vandceuvre Cedex, France.

Jan 1, 1997

By Malti Goel

"Ferrous and non-ferrous metals industries are source of both direct and indirect greenhouse gas (GHG) emissions. Metal industry accounted for 29.7% of the total GHG emitted from the Indian industry sector in 2007. Aluminum is second largest contributor after steel. Indian Aluminum industry has been growing and is adopting several effective measures for better efficiencies through process change and waste utilization. Improvement in the energy efficiency can form the basis of monitoring reduction in emissions. Under the National Action Plan on Climate Change 2008, National Mission for Enhanced Energy Efficiency (NMEEE) aims to upscale the efforts to unlock the market for energy efficiency improvement on a public private partnership (PPP) basis. For a transition to low carbon economy industry is undertaking voluntary measures through scientific and technological innovations both in upstream and downstream sectors. In this paper an attempt is made to overview recent developments in Indian Aluminum industry as well as summarize scientific & technological challenges and prospects.IntroductionAluminum plays a vital role in industrial development. It is a substitute for different type of materials ranging from wood to copper and steel. The aluminum industry has high energy consumption and high contribution to greenhouse gases from carbon dioxide and perfluorocarbons (PFCs) emissions. It is estimated that CO2 equivalent burden of aluminum industry is about 1% of total anthropogenic emissions. The anticipated world growth rate is 3.5% for aluminum demand. Through measures to reduce both direct and indirect CO2 emissions, electricity consumption was reduced from 25 kWh / kg of Aluminum in 1998 to 15 kWh / kg of Aluminum produced in 2008. It is targeted to further reduce it to 10.8 kWh. Aluminum industry is also responsible to about 60% of all PFC emissions. The PFC emissions are harmful to environment, accumulate in surrounding vegetation and contaminate. Efforts to reduce PFC emissions from aluminum industry started early and reduced to 0.5-1 kg / tonne in 1990 [1] from 12-15 kg / tonne in 1940. Since 1990s to 2000 it further reduced to 0.2 -0.4 kg / tonne as seen in Fig. 1. The Global Aluminum Sustainable Development Initiative (GADSI), targets perfluorocarbon (PFC) specific emissions reduction of 80% for 2010 relative to 1990."

Jan 1, 2011

By Zbigniew Zurecki

The selection of atmosphere composition is critical for controlling surface quality of reactive aluminum alloys during solution treatments. An improper selection of annealing atmosphere can result in surface blistering in AI-Mg and sub-surface depletion of lithium in AI-U ingots. To determine optimum atmosphere compositions for homogenizing A1-Mg and Al-Li alloys, Ii number of exploratory experiments were carried out in air, nitrogen, and carbon dioxide based atmospheres including reactive impurities or additive such as moisture and sulfur hexafluoride. This paper describes the influence of these atmospheres on high-temperature oxidation and sub-surface defects. The results are discussed in terms of the change in Pilling-Bedworth ratio.

Jan 1, 1996

By Jay S. Gunasekera

Metal parts are traditionally processed by either filly-liquid (e.g., casting) or filly-solid (e.g., forging) state. Semi-solid metal forming incorporates elements of both casting and forging. In 1991, Gunasekera(5) developed a model illustrating the influence of flow stress by the liquid fraction. The result fits Kiuchi's (1979)(7) experimental data quite well. This model assumed the liquid part is surrounded by solid as small pockets inside the material, which is opposite to the real practical situation. Since the melting usually first happens at the grain boundary, it is better to treat the semi-solid material as small metal crystal surrounded by liquid.

Jan 1, 1997

By Naiyi Li, Henry Hu, Alfred Yu

"In the past few years, various squeeze cast aluminum components have been developed and successfully implemented in various vehicles by the automotive industry because of their superior engineering performance. However, fundamental understanding of the formation of air gap during squeeze casting processes is still very limited despite of its significant influence on the extent of heat transfer between the casting and mould. In this paper, a mathematical model has been developed to simulate phenomena of air gap between the casting and mold' during squeeze casting of aluminum alloys. The model considers the effect of process parameters such as applied pressures and mold temperatures on the events of air gap formation. The predication indicates that the occurrence of highly enhanced heat transfer in squeeze casting of aluminum alloys primarily results from the presence of excess applied pressures.IntroductionA number of squeeze cast Al components has been developed and used in mass-produced vehicles in the past few years, such as steering knuckles, Road wheel, Engine Block etc. This is attributed to their superior engineering performance. In squeeze casting, the cooling rate can be increased by applying high pressure during solidification which results in the noted refinement in the micro structure scale leading to better casting properties. However, the excessive pressure increased interfacial heat transfer coefficient is affected during the solidification by air gap formation and die surface condition etc., which is believed to increase thermal resistance at the casting/die interface [l - 4]."

Jan 1, 2004

By Nicholas Zabaras, Deep Samanta

"Solidification of metal aluminum and aluminum alloys is modeled on uneven surfaces characterized by sinusoidal curves. Wavelengths and amplitudes of these sinusoidal surfaces are varied to study their effects on processes like solidification, macro-segregation and inverse segregation. Solidification and macro-segregation are modeled using a slightly modified form of a stabilized finite element method developed recently to model high Rayleigh number solidification and porous media flows. For pure metal solidification, the effect of varying amplitudes and wavelengths is observed in heat transfer, fluid-flow ~nd phase change processes. The relative importance of shrinkage driven flow and solutal convection on the redistribution of solute for an alloy solidifying in a rectangular cavity is compared. The analysis is then extended by modifying one of the surfaces to a sinusoid. In this case the effects of varying amplitudes and wavelengths are studied in heat transfer, fluid flow, phase change, macro-segregation and inverse segregation processes.1 IntroductionTransport phenomenon during solidification of alloys is a major cause ofcasting defects such as segregation, micro-voids, hot tears, porosity, internal and surface cracks. Heat flow across metal and mold surfaces directly affects the phase change process and plays an important role in determining freezing conditions within the metal. In alloys, natural convection and shrinkage play an important role in determining the final solute redistribution, macrosegregation and evolution of solid macromorphology. Surface unevenness plays an important role during the early stages of solidification. It influences the heat transfer rate and fluid flow in the melt, which in turn affect the morphology and shape of the solid-liquid interface. The effect of surface unevenness on solute redistribution is important during solidification of alloys, where solute driven flow in the mushy zone is prominent. Thevik and Mo in [7] and [8] used a one dimensional model for studying surface segregation and macrosegregation in alloys under the influence of exudation and solidification shrinkage. Air-gap formation in their model was expressed through a variable convective heat transfer coefficient at the boundary. Tsai et al. in [3] and [4] have modeled macrosegregation in an aluminum-copper alloy driven by shrinkage and solutal convection. They used a single domain model based on mixture theory and solved the transport equations using finite difference methods. Our aim is to model solidification of aluminum followed by macrosegregation and inverse segregation in aluminum-copper alloys on uneven surfaces by finite element methods. These surfaces are modeled as sinusoids characterized by amplitudes, ?s and wavelengths, As, By varying As and ?s, changes in heat transfer, fluid flow, phase-change and macrosegregation are studied."

Jan 1, 2004

By W. L. Dalmijn

The processing of scrap and scrap cars starts with size reduction by a hammermill, or shredder. After the liberation the magnetic fraction is removed. The remaining non¬magnetic fraction mixed with other materials is screened and each fraction is processed separately. The increased use of plastic has a negative effect on the recovery of metals and waste production. At Huron Valley, Belleville Michigen, USA, the non-ferrous fraction from 5 million obsolete cars per year, containing 200,000 tons of non-ferrous metal, is processed. Aluminium Is recovered with a heavy medium separation process and concentrated with eddy current separators. The remaining heavy non-ferrous fraction is concentrated by a new combination of eddy current separation and image processing. After this separation process the zinc fraction is melted and refined and the copper, brass, stainless steel and other high-quality concentrates are sold to the secondary industries. The recycling of car scrap has become an important source of metals and materials for the secondary. materials processing industry.

Jan 1, 1995

By Pengfu Tan

In order to understand and control the formation of dioxins and furans in iron ore sinter plants and to possibly avoid expensive end-of-pipe removal stages, thermodynamic calculations on the stability of PCDD/Fs have been combined with sinter process modeling by means of kinetic simulations and computational fluid dynamics. Three thermodynamic databases of PCDD/Fs, derived using the Group Additivity approach and two computational molecular modeling methods, MNDO and PM3, respectively, combined with the SGTE database have been used to model the PCDDIF formation and the PCDD/F isomer distributions in iron ore sintering. The results show very similar conditions for the PCDD/F formation using the different databases. Concerning the isomer distributions of toxic PCDD/Fs, the calculated data derived from the MNDO method showed optimum agreement with measured values from industrial furnaces. The thermodynamic calculations also proved that the isomer distributions found in combustion processes are equilibrium values, while the concentration ratio of PCDDs and PCDFs in the wind boxes does not represent an equilibrium state. A CFD model of iron ore sintering was developed including the kinetics of 15 relevant chemical reactions with the aim of describing the temperature fields and the gas flow patterns in the sintering bed. On the basis of these information and experimental observations reported in the literature possible pathways for the PCDD/F formation in sinter plants have been identified: PCDD/Fs are formed in the critical temperature region of 250 to 450°C below the combustion zone, are then carried downwards with the gas and condensed close to the bottom of the sinter bed. Transported to the discharge end with the solid mixture, they are again released into the gas phase when the flame front approaches the bottom. PCDD/Fs are also formed in the last wind boxes when the hot off-gases cool down and reach the critical temperature range. Consequently, methods to reduce the dioxin formation reactions are proposed including inhibitor addition to the sinter feed and off-gas quenching.

Jan 1, 2003

By Yan Yuan

Stable Nitroxyl polymers, such as poly (2,2,6,6-tetramenthyl-1-piperidinyloxy-4-yl methacrylate) (PTMA), are known to be effective as cathode active materials for lithium rechargeable betteries.The nitroxide radicals displayed a reversible and very rapid redox performances.We present a new synthesized method to get PTMA powder, then a doctor-blading method was used to prepare the PTMA composite electrodes, enabling successful production of homogeneous electrodes. It was characterized through FT-IR and SEM methods.The organic radical battery consists of lithium metal anode and PTMA cathode with an active material content of 65wt%.The best performance is achieved with a thin cathode that shows nearly 100% utilization of the active material (111mAh/g) at 0.1C.Through the electrochemical tests, it was found that there was a stable plateau at 3.5V while discharging. Besides, the cycling stability and rate capability were measured in detail. Although they showed a certain quantity of irreversible capacity on the first cycle, the capacity stabilized after the second cycle.

Jan 1, 2009

By Noel A. Warner

Modern steelmaking is based on direct use of oxygen in high intensity batch reactors. A totally new approach is proposed in this paper, based on the view that pursuit of high intensity is unlikely to lead to successful coal-based continuous steelmaking. By substituting carbon dioxide and water vapor as the oxidants rather than using oxygen directly, the intensity is greatly reduced. Accordingly. subsurface formation of carbon monoxide bubbles can be avoided by careful manipulation of the three participating rate processes, gaseous diffusion, interfacial chemical kinetics and liquid phase mass transfer. Steelmaking can then be carried out without explosive ejection of molten droplets and the generation of micro-spray but rather in a controlled and fumeless fashion. The vital component is the introduction of generic melt circulation technology. Three melt circulation loops in series are envisaged. Starting with a composite feed of iron ore fines, pulverized coal and lime flux, a metallized solid raft floating on molten iron is propelled out of the ironmaking loop onto the first of two downstream steelmaking loops. In the first, a liquid slag is formed, primary decarburization is undertaken not with oxygen but rather with CO2 and H2O and the melt is desulfurized. The semi-product stream enters the third melt circulation loop, where open-channel decarburization is effected along with dephosphorization to yield a low carbon steel product. Alternatively, the melt leaves the last loop to irrigate a packed tower countercurrent to argon at around 100 mbar to continuously produce ultra-low carbon (ULC) steel.

Jan 1, 2003

By Huang Kai

Uniform needle-like and spherical nickel oxalate particles were prepared by the chelating precipitation process, which was based on the reaction of oxalate acid and the solution of ammonia nickel chloride. The molar ratio of ammonia to nickel ion in the mixed solution is essential to determine whether the spherical or needle-like particles are formed, which means actually the concentration of ammonia is the key to determine the growth mechanism. When oxalate acid is added in the form of solid, it may act as the nucleation interface for the eariy-precipitated substance and so induce the formation of spherical particles. The PVP agent can improve the dispersing degree of the needle-like particles and higher reacting temperature leads to larger particles. The composition of the needle-like particle consists of ammonium and nickel oxalate instead of the pure nickel oxalate.

Jan 1, 2003