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By Erich Hovestädt, Hans-Jürgen Odenthal, Christian Wuppermann, Herbert Pfeifer, Antje Rückert

"During the argon oxygen decarburization (AOD) process high-chromium steel melts are decarburized by oxygen and inert gas injection through sidewall nozzles and a top-lance. Due to the large amount of the injected processing gas, low frequency oscillations of the vessel can be observed. It is suspected that these oscillations can influence the converter's structure. The exchange of forces between fluid and the surrounding vessel is the focus of this study. An oscillation model was developed and tested, one objective being to limit the computational effort which is necessary for fully coupled and time resolved CFD and FEM simulations. Experimental results obtained from water-model studies as well as from on-sight measurements are available and were used in order to validate the numerical results. The authors' intention is a contribution towards a more in depth understanding of the factors influencing vessel vibration during the AOD process.IntroductionDuring the last four decades the AOD process has been established as a reliable and efficient refining process in stainless steel making. The injection of process gases (O2, N2, Ar) through sidewall nozzles shows advantages in mixing effectiveness compared to other injection geometries e.g. bottom blowing [1]. Stainless steel grades contain usually more than 10% chromium. With decreasing carbon content during the decarburization periods the tendency of chromium oxidation increases according to the varying chemical equilibrium which depends on the partial pressure of carbon-monoxide (CO) in the gas phase. That's why oxygen is gradually replaced by inert gases, usually argon or nitrogen, in order to lower the CO partial pressure and thus to minimize chromium oxidation. Despite the high injection velocity of approximately Ma = 1, the kinetic energy of the gas jets is consumed within a short distance from the nozzle exits due to the large density ratio between gas and melt of approximately 1:8000. With increasing distance to the nozzle exit, the initial horizontal velocity of the gas jet decreases and due to buoyancy force motion of the detached bubbles turns into a vertical direction. Subsequently a gas plume develops with its typical conical shape described by various authors [1-4]. Due to the drag force between gas bubbles and melt also the liquid phase is forced into a vertical motion. Near the free surface and the wall regions the melt flow is deflected in different directions. Subsequently, the typical flow pattern in the AOD vessel arises, as sketched in Figure 1 and described in literature [5-9]."

Jan 1, 2012

By Jie Li, Liangxing Jiang, Yexiang Liu, Junfeng Gui, Bo Hong, Xiaocong Zhong, Yanqing Lai, Xiaoying Yu

"Pb-based alloys with Pr and Ag were prepared in vacuum electromagnetic induction furnace. The tensile strength, corrosion rate and anodic potential in sulfate solution were measured, and the experimental data were analyzed according to the metallographic phases of alloys, the micromorphology and composition of their oxide films. The results show that, with the addition of Pr, the ultimate tensile strength and corrosion rate of pure lead were increased, and the anodic potential decreased. The extra addition of Ag can improve the properties of alloy further. Comparing with Pb-Ag0.8 alloy which is widely used in zinc electrowinning industry, the ultimate tensile strength of Pb-Ag0.6-Pr2.0 alloy was increased by 31.75%, the anodic potential under 50mA/cm2 was decreased by 30m V.IntroductionIn zinc electrowinning industry, the Pb-Ag (0.5-1.0 wt.%, 0.8wt.% normally) anode is widely used as an insoluble anode['l. It can meet the basic requirements, but still has several problems such as high oxygen evolution over-potential (about 860mV), unsatisfactory corrosion resistance, lead contamination of the cathode product and high consumption of Ag etc.In order to reduce the energy consumption, enhance the corrosion resistance, improve the product quality and reduce the consumption of Ag (or even dispense with it), much research has been done, mainly focusing on Pb-based alloy anodes and Ti-based coated anodes. Detailed investigations have already been carried out on binary alloys (Pb-Ca and Pb-Co), ternary alloys (Pb-Ag-Ca, Pb-Ag-Ti, Pb-Ag-Sn, Pb-Sr-Sn, and Pb-Ca-Sn) and quaternary alloys (Pb-Ca-Sr-Ag, Pb-Ca-Ce-Ag, and Pb-Ag-Sn-Co)[Z-4l, Although these anodes can effectively reduce the consumption of Ag, only the Pb-Co and Pb-Ag-Sn-Co anodes perform well with regard to reducing the anodic potential. However, their complicated manufacturing conditions restrict further commercial use.Besides its application in nonferrous metal electro-winning industry, Pb-based alloy is also used as grid alloy for lead-acid battery, serving as active materials supporter and current collector. In order to enhance the corrosion resistance and deep-cycling performance, reduce the impedance of the corrosion film, the addition of appropriate rare earth elements into anodic grid alloys has become a research focus. Studies proved that RE can enhance the mechanical strength of grids, inhibit the formation of anodic Pb(II) film on the surface of grids and then reduce the impedance of the film[ 10-12l."

Jan 1, 2013

By Keith E. Forrester

This paper presents results of laboratory and field optimization of a proprietary processes developed by FESI for the stabilization of heavy metal bearing wastes. The specific waste studies presented within the paper include foundry ash, aluminum sweat furnace ash and a heavy metal contaminated soil. The FESI process chemistry and engineered processes were found to be the most cost efficient demonstrated and available method of stabilizing heavy metals and highly successful in passing regulatory limits.

Jan 1, 1994

By Haldun Kurama, Cenk Karakurt, Ilker Bekir Topçu

"The usage of binders or pozzolanic materials in the production of concrete is not new. However, in recent years, the use of the pozzolanic siliceous material such as natural zeolite and coal combustion ash (CBA) has received re-attention due to the generated considerable interest in the economical use of both naturally occurring raw materials, recycling of the waste material and saved energy. In this study, the potential and utilization opportunities of natural zeolites and bottom ash (BA) in concrete applications were reviewed. Case studies, conducted to determine the possible usage of the natural zeolite and BA in concrete production, i.e. light weight concrete (LWC) were also presented. The physical and mechanical properties of cured concretes were examined to find out the competitive material usage on the final product properties. Autoclaved aerated concrete (AAC) with 1.1 nm tobermorite (5CaO 6SiO2 5H2O) as binder is a lightweight construction material that mainly uses in place of concrete to manufacture various building materials, including blocks, panels, slabs and the like. The material is a mixture of sand, lime, cement, gypsum, water and an expanding agent, which causes the raw material to rise like bread dough, with countless small air pores. AAC can be molded and cut into precisely dimensioned units and cured in an autoclave, which steam cures the concrete under pressure. During this process, the ingredients combine to form the calcium silicate hydrate gels that establish the special properties of the finished product. The process produces a material that is only one-fourth to one-third the weight of a conventional concrete block (bulk density of 400-800 kg /m3) of the same size. Regular AAC offers considerable advantages over other construction materials such as high thermal and sound insulation, excellent fire resistance, high resource and energy efficiency, low environmental impact, and finally outstanding structural performance (especially for earthquake zones) [1]. Its lightweight also makes it easy to use during construction, and its aerated structure gives it better thermal insulation and sound absorption properties than conventional concrete."

Jan 1, 2008

By David G. Dixon, Ahmad Ghahremaninezhad, Edouard Asselin

"In this study pertaining to the electrochemistry of chalcopyrite, the active/passive behavior of a chalcopyrite electrode in 0.5M sulfuric acid solution was investigated. Potentiostatic and potentiodynamic polarization and multi-cyclic voltanunetry were conducted to analyze the electrodissolution parameters of the electrode.The potentiodynamic and potentiostatic polarizations of chalcopyrite revealed the formation of a passive film on the surface of chalcopyrite. From the potentiostatic study in the passive potential region, a decrease in the dissolution current density by increasing the potential was observed. From this, it was concluded that the passive film is an n-type semiconductor and cation interstitial defects or anion vacancies are the charge carriers. From multi-cyclic voltammetry studies, four cathodic peaks at - 0.37, 0.30, -0.10 and-0.20 YsHE were detected on the surface of a passivated chalcopyrite electrode. The cathodic peaks at 0.37 and 0.30 V were connected to ferric to ferrous reduction and copper sulfide formation, respectively. The peaks at -0.10 and - 0.20 were related to chalcopyrite reduction. The products of the chalcopyrite reduction reactions were suggested to be Cu2S, Cu9fesS16 and Cu5feS4 and evolution of hydrogen sulfide gas (H2S).IntroductionChalcopyrite is the most abundant copper bearing mineral in the world and its dissolution behavior represents the most important technological consideration in the hydrometallurgical extraction of copper [I]. Since the current pyrometallurgical methods for copper extraction from chalcopyrite have environmental issues, many studies have considered the leaching and dissolution of CuFeS2 in different aqueous media [2-5]. The main problem associated with leaching processes is the slow dissolution rate of the mineral [6]. During the dissolution process, increasing the potential of the chalcopyrite in the anodic direction will cause the formation of surface layers which hinder the dissolution rate of the mineral [7]. The precise composition of the layers is in dispute. Previous studies have concluded that these layers could be sulfur [8-9], precipitated iron compounds [8], a solid electrolyte interphase (SEI) - which slows the rate of electron transfer- [10], a metal deficient sulfide [ll], or polysulfidic in nature [12-13]. In order to increase the leaching kinetics of chalcopyrite, the characterization of the layers formed during dissolution is essential and electrochemical methods are important to this end. Studies by Biegler [14] show nucleation and growth of a thin two-dimensional sulfide phase on the surface of chalcopyrite during the exposure of a polished sample in HzS04 solution or air. More studies by Biegler and Swift [15] have shown evidence for nucleation and growth of a 3-dimensional phase at low anodic potentials (around 200 mV vs. OCP). The current-time behavior of the dissolution process in this potential area has the characteristics of expansion and overlap of localized dissolution centers."

Jan 1, 2012

By Andre Krzysik

"Fluidized bed technology has been used in the industry for almost 100 years. To fully understand the process hundreds if not thousands of researchers were and are involved in finding the way to predict the behavior of the solids when subjected to the flow of media through them and the conditions of the solids in the fluidized state. The difficulties in predicting the behavior of solids in the fluidized state stem from the complexity and abnormality of the parameters related to the solid particles. Theoretical calculations can in some degree account for some of them. Particle size distribution, their shape, density, moisture content and physical and chemical reaction that may exist in the fluidized bed reactor play an extremely important role and influence the behavior of the fluidized bed. This paper focuses on the practical examples of the fluid bed equipment and the use of different conditions to process various products.IntroductionEach process application has its own unique requirements and the designers of the equipment must take into consideration specific process requirements, specific properties of the material to be processed (both physical and chemical), and physical and chemical reactions/changes that are taking place in the reactor (heat and mass exchange, chemical reactions, isomorphic change etc.). Each individual piece of equipment must also satisfy specific requirements/ preferences of the client that will operate and maintain the equipment. Those often represent greater challenges than the process on its own, and are equally important to the satisfactory operation of the plant. That includes aspects like location of the equipment, environmental effects, and expected life of the equipment, process control, access, maintenance, and many others.Over the period of time a great deal of research, both theoretical and practical have been carried out and the results of that work are available for equipment designers. For the simple applications that information is usually sufficient and the selection of a suitable solution is relatively simple. In many instances, the available information is not sufficient, and often specialized test work needs to be conducted to obtain additional data. In many cases a pilot installation is built in which the required process is tested. Only then the commercial equipment is designed. The following deal with specific installations that were designed to satisfy specific requirements. In some instances, additional problems were discovered during the commissioning of the equipment that required on site modification. The continuous monitoring of the equipment that was supplied to the various clients allowed us to further develop and improve our designs."

Jan 1, 2014

By C. L. Kusik

Environmental issues are having a significant impact on how automobiles are designed and ultimately disposed of at the end of their lives. On one hand, increasing concerns about landfill disposal have resulted in greater attention being focused on recycling materials and components from old junk autos. On the other hand, corporate average fuel economy (CAFE) requirements have led to downsizing, use of coatings, materials substitution and other measures that often make recycling more difficult. Automobile makers have responded to Corporate Average Fuel Economy (CAFE) Standards in a variety of ways such as: Downsizing; Designing of more fuel efficient engines; Reducing aerodynamic drag by sleeker body designs; Redesigning by using thinner gauges of coated steels; and Substituting material such as lightweight plastic or aluminum parts for steel. Other driving forces affecting production techniques, choice of materials and recycling issues include the Clean Air Act and its amendments, RCRA. and other environmental legislation. The variety of materials used in automobiles makes the recycling issue extremely complex. Not only does one have different materials used in different automobiles for making similar parts, but changing designs, evolving environmental issues, landfill closures affecting solid waste disposal, and increasing raw material quality standards have created a complex set of dependencies related to materials use and recycling.

Jan 1, 1994

By Andreas Stieben, Pierre Lutomski, Wolfgang Bleck, Martin Fischer

"For steel investigation and development, exact knowledge about the microstructural state is required. The information gained from 2D images often can't properly reflect the real 3D microstructural properties. In order to gain reliable information for meaningful models, simulations and correlations, it is necessary to accompany standard metallography with 3D information, which, unfortunately, is very difficult to access. This article presents a procedure for serial sectioning in combination with light optical microscopy. Only standard metallographic tools are employed in combination with image manipulation freeware. 3D microstructural data were extracted from three multiphase steel grades and in two cases virtual 3D-models of microstructural phases were generated.Three Dimensions Of MicrostructuresSince the invention of steel, craftsmen, inventers and engineers tried to improve its properties and tailor them to the requirements of new developments. For systematic development and enhancement of steels, the capability to investigate its inner structure is highly important, because it represents the linchpin between material production and properties. By having an in-depth understanding how production conditions form the microstructure and also how the microstructural state determines the material properties, steel design can be drastically improved. With this knowledge, microstructures can be designed to provide target material properties and process conditions can be identified that form these structures. Due to the key role of microstructure, the capability to gain accurate information about it is indispensable. It is the task of metallography to access and extract descriptive quantitative microstructural data like fractions, sizes, shapes and distributions of the different constituents. The most commonly used investigation tool in metallography is the light optical microscope (LOM). Besides this tool, additional high resolution techniques like Scanning Electron Microscopy (SEM) or Transmission Electron Microscopy (TEM) have become increasingly important. With these and other available methods, extensive information on the microstructural state of a material can be gained. Unfortunately, most metallographic methods have a major loss of information systematically built in. Analyses of microstructures are usually performed on surfaces, i.e. on 2D areas that emerge by cutting through the 3D material structure. This means, a complete dimension of information is not taken into account. How serious this reduction of information is and how it can affect interpretation of structures is exemplarily demonstrated in figure 1, which displays the planar structure emerging from a random cut through a simple 3D structure. It is very difficult to deduce or even imagine the original spatial structure from which this projection emerged and it is impossible to reconstruct it with absolute certainty without further information. The image has emerged from a random cut through a 3D structure of stacked cubes that is displayed in figure 2. The area shown in figure I is outlined. Although artificially constructed, this example demonstrates how distorted and misleading the view on structures can become by ignoring a spatial dimension."

Jan 1, 2012

By Guolin Zheng, Tiejun Chun, Jian Pan, Deqing Zhu, Xianlin Zhou, Dong Chen

"The high temperature oxidizing-chloridizing roasting is one of useful methods to separate nonferrous metals from pyrite cinder and metallurgy slag. However, as one kind of main nonferrous metals in pyrite cinder and metallurgy slag, copper’s chlorination behavior is not demonstrated. In the present study, chlorination behaviors of CuO, Cu2O and CuS at the temperature range of 1025-1175 ? in air by simulating the chloridizing roasting process of pyrite cinder and metallurgy slag have been investigated. It is shown that Cu2O and CuS is much easier to remove, CuO is refractory to remove. In addition, the presence of SiO2 and CaO increases the Cu removal rate from CuO while the presence of SiO2, Al2O3, CaO and MgO decreases the Cu removal rate from Cu2O. Fe3O4 influences the Cu removal rate from CuO and Cu2O positively.IntroductionAs two kinds of significant secondary resources, pyrite cinder and metallurgy slag contain not only abundant iron but also considerable copper, lead, zinc etc. Millions of tons of pyrite cinder and metallurgy slag were discharged from nonferrous metal and chemical industries annually [1, 2] in China. The pyrite cinder and metallurgy slag are formed by roasting of minerals at a high temperature, so the properties of them are distinctly different from the natural iron ores, and the iron in them is closely associated with copper, lead, zinc and other nonferrous metals. High-quality pyrite cinder and metallurgy slag containing high iron and low impurities can hardly be obtained, leading to their low utilization degree [3]. Chlorination is characterized by the high reactivity of chloridion, the high volatility and low melting point of metal chlorides, and the big differences in the formation of metal chloride. Therefore, chlorination is widely applied in extraction metallurgy."

Jan 1, 2012

By Lee Fergusson

"The primary features of ViroMine™ Technology are introduced and applications of ViroMine™ Technology to mine site remediation and the treatment of a variety of intractable waste-streams, including a technical discussion of acid neutralizing capacity, metals binding capacity and longterm stability of results. Outcomes from four applications at high-profile international mine sites are presented: 1) the superfund site at the Gilt Edge Mine, South Dakota, USA (four years of data on the treatment of acidity, TDS and metals such as Al, Co, Fe, Mn and Zn); 2) one of Australia’s most polluted sites at King River Delta in Tasmania (treatment of TAA and TPA, and metal and metalloid contaminants such as As, Cr and Hg); 3) The Aljustrel “Aqua Forte” mine site in Portugal (high acidity, metal and metalloid contaminants such as Al, As, Cu and Zn) and 4) the Ulsan Iron Ore Mine at Ulsan, South Korea (treatment of metal and metalloid contaminants such as As, Cd and Ni).IntroductionThe commercialisation of ViroMine™ Technology has resolved some of the most intractable pollution issues associated with historic mining ventures on a global scale and has facilitated the neutralisation of Acid Rock Drainage (ARD), remediation of acidic and metal contaminated impoundments (including tailings dams) and promoted revegetation on tailings deposits and waste rock dumps. ViroMine™ Technology also enables current mining ventures to manage effluent simply and efficiently to meet increasingly stringent environmental standards and is enabling the mining sector to reconceptualise the management of mine spoil. The abilities of ViroMine™ reagents to neutralise the actual and potential acidity of sulphidic mine spoil coupled with the ability to bind metal and metalloid contaminants into non-bio-available forms are the key features delivering environmental and economic benefits to the mining sector and the broader community. Results from four projects utilising ViroMine™ Technology are presented to highlight the suitability of ViroMine™ Technology to treat all forms sulphidic mining wastes. 37"

Jan 1, 2008

By V. B. Telles, D. C. R. Espinosa, J. A. S. Tenório

"The purpose of this work was to study the reutilization of the steelmaking dust, derived from steel production in the electric arc furnace (EAF), in iron ore sintering process aiming zinc elimination. In each sintering process were collected sintered samples, these materials were analyzed by chemical analysis using atomic absorption spectrophotometry in order to determine the zinc content. Samples of not sintered mixtures were also characterized by chemical analysis aiming to determine the initial amounts of zinc, i.e. in order to check the zinc amounts present in the mixture before the sintering process. The comparation among the zinc contents of samples sintered and not sintered allowed to determine the elimination of zinc during the experiments. Results showed that the zinc elimination in the process is proportional to the ratio reducer/waste. The zinc removal was lower when the reducer/waste ratio was decreased.IntroductionThe electric arc furnace dust (EAFD) is a residue generated in the steelmaking process using electric arc furnace. Aproximately 30% of all steel produced (in the year 2009) was obtained through electric arc furance (EAF). In the United States of America the percentage of this process in the total crude steel production was about 62% in 2009, while in 2000 this percentage was only 47% [1].The iron ore sintering is a process that reuses wastes generated in metallurgical industries. However, the materials used must be physical and chemical characteristics compatible with the blast furnaces.The quantity of zinc, cadmium, chrome and other metals present in the EAFD depends on the quality of the scrap used to feed the EAF and the type of steel that it is been made [2,3]. The reuse of EAFD waste is interesting to steelmaking processes because of its iron content. However the presence of zinc inside a blast furnace is undesirable since the zinc oxide can be deposited on the blast furnace walls and in the drivers of gas output, interrupting the flow. Another part of the zinc oxide can form deposits on the refractory lining of the blast furnace [4,5]."

Jan 1, 2012

By Antonio de Ita, Isaias Hilerio, Miguel Barron

"The influence of an unconventional lance with a central nozzle on the multiphase fluid flow in a steelmaking converter is studied in this work by means of computer simulations. The lance has four peripheral supersonic nozzles and a vertical central nozzle. Besides, the oxygen flow in the central nozzle is considered independent from the main oxygen supply. Transient two-dimensional numerical simulations were carried out considering just molten steel and gaseous oxygen as the existing phases. Numerical results show that bath agitation and droplet generation are enhanced as a result of the central nozzle. However, the performance of this lance strongly depends on the distance of the lance tip to the molten steel surface and the velocity of the oxygen jet.IntroductionCurrently, two thirds of the world crude steel is produced through the steelmaking oxygen converter [1]. Given the unquestionable economic importance of this technology, any improvement or optimization proposal is welcome. In the majority of current oxygen converters a top oxygen supersonic jet is blown onto the molten steel through a water-cooled lance to eliminate by oxidation some impurities such as carbon and phosphorus. Conventional lances have inclined peripheral nozzles whose number depends on the converter capacity. During the process, a large amount of gases evolves, forming metal droplets and a metal-slag-gas emulsion [2]. The droplets and the resultant emulsion increase the reaction interfacial area, promoting in this way carbon removal and dephosphorization of the molten steel bath [3]. However, during the blowing stage, the emulsion rises towards the lance and converter mouth and frequently forms layers which accumulate in the lance, reducing the life of the lance tip [4, 5]. It is possible that some freezing of the molten metal occurs due to the low oxygen injection temperature, however there are no reports on this. Besides, frequently undesirable operating phenomena such as spitting and slopping may arise as a result of inappropriate blowing practices or bad lance design. In the oxygen steelmaking industry, novel lances design are needed in order to enhance the decaburization rate and the slag formation and, at the same time, preventing operating practices that decrease productivity and move away the shop from safety standards."

Jan 1, 2012

By Alva L. Kuestermeyer

This paper presents the results of an economic analysis in the production opportunities of various co-product and minor metals in the base metals smelting 'industry. Pro forma cash flow statements were prepared for each co-product and/or minor metal analyzed utilizing US tax laws for items such as depreciation and taxes. The generated cash flows are based on anticipated revenues, estimated capital and operating costs (where applicable), and nominal production data for the respective co-products and minor metals. The economic analysis includes consideration of items such as metal payfors and bonus metals ,payments per current smelting terms. Sensitivity analysis to market prices is also ,addressed.

Jan 1, 1995

By Thomas Niehoff

"Oxyfuel combustion systems are state of the art for many melting operations. Airfuel systems have been stepwise modified to oxygen enrichment, oxygen lancing and oxyfuel. Every change of the melting process will have consequences with regards to emissions and energy usage. The uniqueness of many operations requires unique skills to resolve potential issues. This paper will give some examples of how airfuel systems can successfully be converted to oxyfuel.IntroductionOxyfuel technology – meaning the combustion of fossil fuels such as natural gas, oil or coal with technical oxygen instead of air for industrial melting or heating processes is widely used in many industries these days. Even though oxygen production, storage and handling has been state of the art for decades other opinions exist. Often oxyfuel is regarded with fear and potential hazards like: “Oxygen makes the process too hot.”, “Oxygen will melt away the refractory.”, Liquid oxygen is dangerous.”, “Oxygen will cause explosions.”, ……etc.Typically a more detailed discussion about a specific industrial process and how oxygen can be applied in a safe and economic way the seeming issues go away."

Jan 1, 2010

By Vladimir Kislik

Competitive complexation/solvation theory of solvent extraction constitutes a general framework for interpretation and quantification of ion-molecular interaction data in extraction systems. Depending on extracting metal -- solvent affinity constant and metal concentration ratios, four possible stages of extraction behavior and interacting mechanisms, are considered. Affinity constant ratios are easily acceptable through the independent measurements of three-component systems. Once determined and tabulated, the affinity constant ratio data may be used in any system of interest. Mathematical descriptions of the results are introduced for different interactions. Active solvent (including water) concentrations in the organic phase and temperature are included to the quantitative consideration. The theory allows direct comparison of the complexing/solvating power (competition order) of various extractants, active solvents and diluents. As a result, predictions for the extraction effectiveness and selectivity are possible. Some metal extraction systems are analyzed on the base of the theory. Analysis gives a key for preliminary quantitative prediction of suitable extraction systems.

Jan 1, 2003

By M. -V. Wang

Hydrotreating and hydrorefining (HT and HDS) spent catalysts contain molybdenum, vanadium, nickel or cobalt at concentration levels that can make metals recovery economically viable. Quanzhou Jing-Tai of China has developed, through many years of operating experience in metal recovery from spent catalysts, a simple process for recovery of these metals and the production of environmentally benign residues. The process first subjects the catalysts to a low-temperature calcination step, followed by grinding of the calcine. The ground material is then leached with 10-20% v/v hydrogen peroxide to recover metals such as Mo, V and Ni or Co. This step has a selectivity that is greater than 95% for the metals. The undissovled residue, which contains mainly Ah03 and Si02, can be dewaterd and used in the production of masonry bricks. The pH of the rich liquor is then adjusted to between 0.5 and 2.5 by adding dilute sulfuric acid to co-precipitate Mo and V, with a recovery rate of greater than 99%. The lean liquor contains mostly dissolved Ni or Co, which can be recovered through precipitation at a pH of between 8.5 and 9.5 by caustic additions. The final liquor is then sent to an ion exchange step for final recovery and cleanup of residual metals. The effluent is then discharged after a simple wastewater treatment process, which has been found to meet all environmental requirements. The entire process has been found to be simple, cost-effective with minimal environmental impacts while achieving the goal of complete resource recovery from spent catalysts commercially.

Jan 1, 2000

By Patrick F. Mahoney

Each year in the United States over 10 million tons of metal are discarded with our municipal waste. This, includes, not only ferrous metals, aluminum and copper but gold, silver, platinum and every other precious metal. Resource recovery, as an approach to waste management, is replacing disposal and it presents great opportunities for those in the metal refining and recovery industry. Combustion of waste enriches the metal fraction left in the ash to the point where metals can be efficiently recovered. The recovery and quality of metals can be enhanced by good combustion control. Innovative technology is needed to efficiently tap this generous, and renewable mine.

Jan 1, 1995

By Greg Dowling, Jun Ge, George Shannon, Shufeng Yang, Yongfeng Chen, Lifeng Zhang

"Inclusions in 316L stainless steel ingots poured using two different upgate designs – a traditional upgate and a swirl upgate - were investigated using SEM and ASPEX automated inclusion analysis. The main inclusions were high SiO2 inclusions, MnS inclusions and SiO2-Al2O3-CaO inclusions. More inclusions were detected at the top of the ingot than other places in vertical direction, and more inclusions were at the edge of the ingot than other place in the radial direction. With swirling upgate there were more K- and Na- bearing inclusions than that with the traditional upgate indicating possible more serious flux entrainment with the swirl upgate.IntroductionIngot casting still is very important for production of special steel grades including high carbon chromium bearing steel, thick plate, seamless tube, forgings, bars, and wire rods [1] . During the bottom teeming process, molten steel enters the trumpet and passes through the spider into the runners. Molten steel then enters the ingot mold through an upgate near the end of the runner. In the early stages of filling a mold, a mold flux bag hung in the mold were burnt and the mold flux will cover the top of the rising steel to protect the steel from being reoxidized, acting as well as act as a thermal insulator. So far, some efforts on studying inclusions characteristics in the ingot have been reported. A review paper on the control of inclusions during steel ingot casting was published by Zhang et al. [2] Zhang also studied Inclusions in bottom-teemed ingots of plain carbon steel and found that the >20µm inclusions originated from either the entrainment of mold flux of the reoxidation during teeming process. [3] The results of Nagendra and Du showed that there were more inclusions in the centre part of the ingot [4]. Eriksson et al reported that the composition of inclusions was more complex in the mold samples in comparison to the ladle samples, and more inclusions in the mold were found than in ladle because of the reaction between the mold flux and the molten steel [5]. It was reported that SiO2-CaO-Al2O3 inclusions originating from mold powder with reoxidation product Al2O3 as a part, and there were more inclusions close to the side wall than the center of the ingot in the radial direction. [6]. A more recent investigation showed that four main types of inclusions in runner samples were classified: oxides, sulfides, complex and carbon-nitrides. [7] The flow pattern in the mold during filling has been found to be an important factor regarding inclusions in the ingot. In the early stages offilling a mold, steel enters the mold through the entry nozzle at a high velocity. The effect of the resulting turbulence on the meniscus can lead to the entrainment of mold flux. Efforts have been paid over the years to find methods to reduce the velocity of the molten steel entering the mold, such as using opening angle of the inlet nozzle [8], using swirl blade at the runner [9], using a divergent nozzle combined with a swirling flow generated in the nozzle [10-11]."

Jan 1, 2012

By Beatriz Ribeiro Nogueira, Vijaya Kumar Rangari, Esperidiana A. B. Moura, Anne Chinellat, Arifa Parveen, Angel Visentim Ortiz

"Composite consisting of ethylene vinyl alcohol (EVOH) with short piassava fibers were prepared by extrusion process and their thermal and morphological behavior were investigated. The EVOH reinforced with 5 and 10 % of pi as sa va (Attaleafunifera Mart) fiber particle, based on the percentage weight ratio (wt %), untreated and treated with a commercial silane coupling agent, were prepared and the influence of fiber loading and the effect of chemical treatment on their thermal and morphological behavior were evaluated by SEM, DSC and TG analyses. Melt flow index (MFI) of the composites have been determined to evaluate the effects of fiber reinforcement on dynamic viscoelastic melt of the EVOH. In addition, piassava fibers characterization by SEM, FTIR, and organic and inorganic composition have also been carried out. The SEM results of the composites showed surface micrographs without microvoids and a good distribution, dispersion and compatibility between the fillers and the EVOH matrix. Concerning the piassava fibers characterization, the results showed that piassava has higher lignin content than cellulose and hemicelluloses, and around 0.7 % of ash with 52 % of silica (Si02). This high concentration of silica is consistent with the SEM analysis of the fiber that showed a large amount of ""silica rings"" encrusted on their surface.IntroductionLately, great worldwide interest has arisen in developing new technologies that enable the use of products with less environmental impact. Effort has been put into seeking natural modifier applications, particularly regarding the use of natural fibers. Special attention has been given to the use of natural vegetable fibers, because of the huge variety of species available. Such vegetable fibers are usually referred to as lignocellulosic materials [1]. This work evaluated the effects of piassava (Attalea funifera Mart.) fiber incorporation in an ethylene and vinyl alcohol copolymer (EVOH). The EVOH belongs to a family of copolymers with excellent gas barrier properties and resistance to organic compounds, which allow its application in different segments, from food packaging to gas tanks. However, EVOH is very sensitive to moisture, and in conditions of high humidity its gas barrier properties, thermal and mechanical properties are affected."

Jan 1, 2012

By Björn Hinzel, Joachim Rösler

"The most important characteristic of open-pored metals is porosity, since it enables all of their functional applications as filters or sound absorbers. Due to the notch effect of the pores, mechanical properties of porous metals are better than the ones of comparable structures made of polymers or ceramics. Consequently, only open-pored metals can be used in aircrafts to reduce flow noise or noise resulting from the core engine by acoustic absorption. Absorption properties depend highly on pore size and porosity of the material, which must be characterized as precisely as possible in order to analyze the correlation between morphology and noise reduction performance. Here, a line segmenting method is explained in order to characterize pore size and porosity of absorber materials using image processing based on two dimensional microscopy images, including sample preparation and specification of the set-up. Then, the influence of the pore structure on the measured absorption behavior is discussed. Finally, the correlation of acoustic behavior, pore morphology, and porosity is outlined.IntroductionSignificant noise loads affect everyone causing anxiety, depression, insomnia and other effects which impair health and productivity [1],[2]. Due to the rising number of flights and aircrafts, air traffic noise increases dramatically. To counter this development, various approaches have been developed to reduce the different noise sources resulting from airframe, jet or engine [3],[4],[5],[6]. One approach to reduce this noise is the application of noise reducing liners in the hot gas path [7]. This is especially important, since the engine is becoming the dominant noise source of modern airplanes during take-off [8]. Due to the elevated temperatures and high fatigue loading in this part of the aero-engine, conventional passive absorber materials cannot be used. Polymers would not be able to bear the heat and ceramic fibers would crack under the mechanical loading due to the notch effect. Consequently, this study focuses on metals with open pores, which can resist elevated temperatures and fatigue loading and additionally resemble geometrically conventional passive absorbers. Based on the production processes, e.g. sintering of metal fibers [7], powder processing using a foaming agent [9], coating of polymer foams [10], or using melt infiltration techniques [11], the characteristic dimension of the porosity is usually in the range of 0.01-10mm. In this work, sintered metals and metal sponges are analyzed after the theory of sound absorption is briefly outlined. Then, measurements of the acoustic absorption of metal sponges and sintered metals in an impedance tube are performed. To understand and predict the acoustic properties of metals with open porosity, it is necessary to characterize the materials as precisely as possible. This is explained in detail using a line segmenting technique, followed by a discussion of the connection of pore characteristics and acoustic absorption. Finally, a conclusion is given."

Jan 1, 2012