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By Rachel De Lucas

In recent years, as the price of oil soars upward, scientists have started to focus on other energy sources, such as hydrogen. As magnesium can be used for hydrogen storage by forming MgH2, industry will see a growing demand for the hydride. In hydrogen storage and release cycles using magnesium, hydrogen is released from magnesium hydride through hydrolysis and magnesium hydroxide is produced. Therefore, recycling magnesium hydroxide back to magnesium becomes important. The solid oxide membrane (SOM) process is an emerging technology for this process. In the SOM process, MgF2-CaF2-MgO flux is contained in a stainless steel crucible, which works as the cathode. An ionic-conducting YSZ membrane, connected to a liquid metal anode, is partially immersed in the flux. During electrolysis, when the voltage between anode and cathode is higher than the dissociation potential of magnesium oxide, magnesium ions move toward the cathode and are reduced into magnesium vapor. The oxygen ions move toward the anode, passing through the YSZ membrane. They are then oxidized, forming pure oxygen, CO/CO2 or steam (by reaction with hydrogen). The magnesium vapor, generated at the cathode, is collected in the condenser as high purity magnesium. SOM experiments have been conducted with different liquid metal anodes and without reductants. The SOM technique is a highly energy efficient process and with by-products being oxygen or steam, it is also an environmentally friendly green process. A 2-D electrostatics mathematical model was developed as an initial step towards optimizing the design for a three-tube scale-up SOM electrolysis cell. Several possible geometries were examined to develop the scale-up model and convergence of the model was achieved.

Jan 1, 2006

By Nozomu Uchida, Uematsu Keizo, Daisuke Shouji

"Grain orientated microstructure was developed for the improvement of ceramic characteristics. Novel polarized light microscopy was developed to examine the grain orientation quantitatively. The degree of grain orientation was estimated from the retardation determined with a Berek compensator. The method was essential to determine a minor grain orientation, which could not be analyzed by means of conventional X-ray measurements. The data were favorably related to ceramics characteristics. The comparis of the ceramics with various degree of orientation was very important to explain the change of ceramic characteristics with processing.IntroductionMicrostructure with grain orientation has a high potential for greatly improving characteristics of ceramic. However, there has been strong restriction on processing and material for developing this structure. It has been crucial to apply forming methods involving high shear such as injection molding1). Grains must have an elongated shape.In recent years, much attention has been paid on the effect of high magnetic field on diamagnetic materials2)3)4), Many ceramic materials are known to be diamagnetic. High magnetic field has a high potential to orient grains. The principal driving force for grain orientation is the magnetic anisotropy of material, which is generated by non-cubic crystal symmetr5). This method of grain orientation is not restricted by grain shape, and can be applied to all materials having non-cubic crystal structure.This study uses alumina as raw materials, and produces alumina ceramics with orientated grain in high magnetic field (10T). Alumina has a magnetic anisotropy due to hexagonal crystal structure. The degree of grain orientation in the green and sintered bodies will be examined and their relevance to magnetic field will be discussed."

Jan 1, 2000

By Jong-Shin Chang

The Onsan smelter has tried to do various activities to decrease operation costs. With several expansion projects, the Onsan smelter has aimed at not only a quantitative growth but also qualitative growth through efforts improving operations equipment and processes. Activities to reduce operation costs have been one of those efforts. In particular, the energy cost of operation has been a main target for reduction. The activities to save energy have been carried out in two ways. One is to recover and utilize waste heat as much as possible and another is to replace existing equipment and processes with more energy-efficient ones. This paper reviews recent improvements and future plans for energy saving activities at the Onsan smelter.

Jan 1, 2006

By Karel Verscheure

Hydrometallurgical zinc leach residue, EAF dust and other Zn-bearing by-products pose potentially serious environmental problems that threaten the sustainability of the operations. A pyrometallurgical process designed for treatment of such residues is the high-temperature submerged plasma Zn-fuming process. The successful operation of this process requires high Zn fuming rates whilst retaining vessel integrity through stable freeze-lining. A Zn-fuming model has been developed and used to systematically investigate a range of operating scenarios and to identify potential fluxing parameters such as CaO/SiO2, Fe/SiO2, MgO/feed-ratios in the input and fluxing additions of dolomite for maximum fuming rates and stable freeze-lining.

Jan 1, 2006

By Suman Das, Justin J. Gambone, Rohan Bansal, Ranadip Acharya

"This paper focuses on modeling of the scanning laser epitaxy (SLE) process that is currently being investigated and developed at the Georgia Institute of Technology. SLE is a laser-based manufacturing process for the creation of equiaxed, directionally solidified and single-crystal deposits of nickel superalloys onto superalloy substrates through melting and resolidifícation of alloy powders using a scanning laser beam. The thermal modeling of the system, done in a commercial CFD software package, simulates a heat source moving over a powder bed and dynamically adjusts the property values for consolidating CMSX-4 nickel superalloy powder. The associated melting and re-solidification process is modeled using an immediate consolidation approach, and the predicted melt depth is compared with the experimental data obtained. For a given position of the beam, geometrical parameters of the melt pool are used to estimate the resulting microstructure. The influence of the processing parameters on the microstructural evolution is also discussed. This work is sponsored by the Office of Naval Research through grants N00173-07-1-G031, N00014-10-1-0526 and N00014-11-1-0670.IntroductionIn order to increase the operating temperature of gas turbine aero engines, investment cast equiaxed turbine airfoils are now often replaced with airfoils that have either directionally solidified columnar or single crystal (SX) microstructure. Wear and damage during operation limits the lifetime of these components and necessitates the replacement of numerous airfoils within the engines. Due to the high cost of producing SX cast turbine blades, the cost of replacing each blade can be several hundred to several thousand dollars. With each engine containing several hundred blades, the cost to replace all blades can reach hundreds of thousands of dollars. Hence, it is of great interest to develop a process that can restore the single crystal microstructure at the locations of material loss and allow for the blades to be repaired and reused rather than be scrapped and replaced."

Jan 1, 2012

By Yasumasa Hattori

Fluid flow in a flash furnace concentrate burner was investigated quantitatively in order to improve burner performance. Computational fluid dynamics was utilized for researching fluid flow in a burner port mathematically then its results were reviewed in the commercial flash furnace burner and its calculation results were found to be in good agreement with the actual measurement results. Based on those results, a mathematical fluid flow model for the Sumitomo flash furnace concentrate burner has been developed so as, to improve premixing and combustion efficiency of concentrate in the reaction shaft.

Jan 1, 2002

By Jeong-Soo, Joon Soo Kim, Rajesh Kumar, Sohn, Jin-Young Lee

"Liquid-liquid extraction (LLE) studies of tetravalent platinum from acidic chloride solutions have been carried out with Alamine 336 as an extractant diluted in kerosene. The title metal shows the inverse behavior at higher acid concentrations. Plot of log D vs. log [Acid], mol.L-1 gave a straight line with a negative slope of 0.8±0.03 indicating the exchange of one mole of hydrogen ions for every mole of platinum(IV) extracted into the organic phase. Extraction of platinum(IV) increases with increase of extractant concentration. The plot of log D vs. log [Extractant], mol.L-1 is linear with slope 1±0.3, indicating the association of one mole of extractant with the extracted metal species. The plot between metal distributions to aqueous to organic phases is 1.3±0.01; it indicates monomeric species was formed in organic phase. Stripping of metal from the loaded organic (LO) with mineral acids such as hydrochloric, sulphuric, nitric acids and bases like ammonia, hydrogen peroxide and sodium hydroxide are studied. The results indicated that hydrochloric acid and sodium hydroxide are the better stripping agents when compared with other acids and bases. Increase of temperature decreases the percentage extraction of metal indicating the process is endothermic. Regeneration and recycling capacity of Alamine 336 and extraction behavior of associated elements such as aluminium(III), magnesium(II), cobalt(II), iron(III) and nickel(II) were studied.IntroductionThe demand for platinum group metals (PGM’s) has risen in the last five years expected to keep in rising. Right now, the demand is already beyond the supply. The primary use of PGM’s today is in the automotive industry. Catalytic converters used in the PGM’s process to reduce greenhouse gases. Because of the current demand to reduce the green house effect the expected need for platinum is here stay. Country’s now advancing in the use of car production also are phasing increasing the needs for this metal. Chemical processing also use it, too. These industries account for more than 50% of all platinum production. Jewelry is other primary use of this precious metal whose value is much greater than gold. Other uses include computer data storage, scientific developments, fuel cell technology and in the glass manufacturing processes."

Jan 1, 2008

By Ludy C. Motta, Denise C. O. Nascimento, Sergio N. Monteiro

"Natural cellulose-based fibers are nowadays of growing interest for modern industrial composites. Relatively unknown fibers like piassava, curaua and gourde have shown promising behavior as reinforcement of polymeric composites. However, the hydrophilic characteristics of the natural fibers impair its adhesion to the normally hydrophobic polymeric matrix. Surface treatments can, in principle, improve this adhesion and the fiber/matrix interfacial strength. In this paper, the effect of alkali treatment of the surface of piassava (Atallea funifera) waste fibers was investigated in terms of the change in strength of epoxy composites reinforced with these waste fibers.IntroductionThe consequences of global warming and the increase in the price of petroleum are motivating the use of natural materials as substitute for energy intensive synthetic materials [1]. In particular, natural fibers obtained both, from cultivated plants such as jute, sisal, hemp and flax as well as from industrial waste such as sugar come bagasse and coir, are being considered to replace synthetic glass fibers [2,3]. These natural fibers, also known as lignocellulosic fibers, present the comparative advantages of being renewable, recyclable and biodegradable. Moreover, lignocellulosic fibers require less amount of processing energy and are neutral with respect to CO2 emission, which causes the atmospheric greenhouse effect responsible for the global warming [4]. Low cost is another important economical advantage of the natural fibers over the synthetic ones and the application of lignocellulosic is also associated with a lower wear of processing equipment and better finishing of molded components [5]. Moreover, for some fibers, properties such as the mechanical strength and impact resistance can be superiors to the corresponding properties of synthetic glass fiber [6]. The characteristics and properties of several lignocellulosic fibers are, nowadays being extensively discussed in the literature. It is beyond the scope of this work to comment on the hundreds of papers dealing with this subject. However, there are still less known fibers with great potential as engineering material that deserves investigation."

Jan 1, 2008

By J. Shibata

The recovery process of valuable metals, such as Ll, Mn, Ni and Cr from a waste lithium battery was developed n this study. Lithium and Mn are selectively leached from the battery by using dilute mineral acid. Main part of the battery comprises stainless steel, and Fe, Ni and Cr are easily leached by the mixture of dilute HCl and HNO3 Lithium and Mn are precipitated as metal carbonates from the? individual leached solution with sodium carbonate solution. The solution containing Fe,Ni and Cr Is treated by solvent extraction to separate NI and Cr from the leached solution. The experiments are carried out for leaching and separation steps. According to the experimental results, the flow. sheet for a recovery process of valuable metals from a waste lithium battery has been established.

Jan 1, 1995

By O. Kitamura, H. Kubota

The Harima Works started its ISP operation in 1966 and been expanding its production capacity from 3,000 tonne Zn/month and 1,500 tonne Pb/month to 7,500 tonne Zn/month and 2,500 tonne Pb/month. It is not only treating zinc, lead and bulk concentrates but also secondary materials like Waelz kiln oxide from the Shisaka Works of Sumitomo Metal Mining, waste treatment sludges, industrial wastes and others. Its final products cover Prime Western Grade (PWG) zinc, Special High Grade (SHG) zinc, continuous galvanizing grade zinc, electrolytic lead, cadmium, indium, thallium and sulfuric acid. This paper briefly describes the smelter's historical and present operations. The key data for the current impurity control management and for the distribution of impurities such as copper, iron and arsenic are presented.

Jan 1, 2000

By A. S. Mustafinova, A. A. Zharmenov

"Production of electrolytic copper is characterized by large volumes of acidic spent solutions the utilization of which requires considerable expenditures of neutralizing agents. At present, an economically substantiated technology does not exist for treatment of sulfuric acid rinse solutions and spent copper electrolyte which will allow for repeated use of the acid and the metal salts. Therefore, for this aim the most advantageous is the use of electromembrane methods. In the paper there is stated the essence of developed technologies which are distinguished by low waste and provide the extraction from the solutions of metallic copper, nickel and sulphuric acid. There are also considered methods of copper electrolyte processing allowing to regulate its composition by that or another component (H2S04, Cu, Ni, As).On the base of the detailed study of the behaviour of various types of ion- exchanger membranes in copper-, nickel-, zinc-, arsenic- bearing sulphate solutions there is realized the selection of the most suitable membranes (MK -401, MA-411, MB-2 and MKL-l/MAL-2).Some variants of electro membrane processing of spent solutions of the hydrometallurgy process have passed productions tests on a number of copper-electrolyte enterprises of the countries of CIS (cooperation of Independent States). These tests showed high efficiency of developed methods."

Jan 1, 1997

The entrainment of copper matte in the slag during the slag skimming stage of a Peirce-Smith converter was studied with a dam break model. Experiments were carried out with a range of fluid pairs where the lighter fluid was allowed to overflow a weir and the amount of entrained heavier fluid measured. The resulting entrainment is measured as the ratio of the heavy to light fluid withdrawn. The fluids include oil-water, water- glycerol and salt solutions-water pairs to cover a wide range of densities and viscosities. It was found that the Richardson number, Ri, correlates the entrainment well. For the case of the liquid-liquid interface initially at the same height as the weir, the entrainment was found to vary with Ri-1/3. The transient flow was simulated with a volume of fluid (VOF) code written in-house and used a stairstep approach to represent flow obstacles. The code was validated against the experimental results with good agreement for the variation of the heights of the two fluid with time. The simulation showed that the prevailing mechanism for entrainment is due to a pressure differential created across the liquid in the converter during pouring resulting in the heavier liquid being rotated upwards and over the weir.

Jan 1, 1999

By Georgina De Micco

The National Commission of Atomic Energy is investigating a suitable physicochemical process for the conditioning of spent nuclear fuel and treatment of the scrap of research reactors of the Al-UxSiy type. A possible way of processing is through dry chlorination of the cladding with the purpose of selective separation of the aluminium from the remaining elements such as Fe, Ni, Zn, Cu, etc. transforming them into volatile chlorides. Some important advantages of this method are the thermal stability of the chlorides that allow the easy separation of the halides by physical methods and the low volume of radioactive waste generated. The interactions in the following systems were studied in the range of temperature between 150º-500°C: Al-Fe, Al-Ni, Al-Cu, Al-Zn, Cu-Zn and the pure metals. We found that the reactivity was different depending on if the elements were alloyed or separated. The separation factors of the systems under study were determined. Nickel is perfectly separated from aluminium for all temperatures, whereas good conditions for copper separation were achieved below 400ºC. In the case of iron, complete isolation was never attained. However, by decreasing temperature to 150ºC it is possible to obtain aluminium chloride with less iron content. The separation of zinc from the product was also difficult. It was detected that zinc chloride volatilization decreases when other chlorides were present, for example cooper chlorides. In the Cu-Zn alloy, zinc chlorides remained in the condensed product due to interactions with copper. The samples were characterized by scanning- electron microscopy (SEM), X ray diffraction (XRD) and atomic absorption.

Jan 1, 2006

By Iris Filzwieser

The secondary copper producer, Montanwerke Brixlegg AG (Austria), produces 73 000 tonnes of cathodic copper per year using ISA tankhouse technology. METTOP GmbH (Austria) evaluated the different anode qualities from the plant with relation to the current efficiency and specific energy consumption. Parameters including the chemical and physical anode quality, current and current density distribution at each cathode, voltage, and distance between each cathode and anode were examined. In addition, the temperature, chemical analysis, and conductivity of the electrolyte was determined for each investigated cell, as well as the anode weight, anode scrap, cathode sheet, and short circuits. Metallographic analysis was also performed on selected dendrites. The investigations resulted in specific improvements in the tankhouse process including the level of anode impurities, and future projects are planned for further tankhouse optimization.

Jan 1, 2006

By Xinli Wang, Matthew Andriese, Jiann-Yang Hwang, Zhiwei Peng, Byoung-Gon Kim

"The microwave dielectric properties of silicon dioxide at frequencies of 915 and 2450 MHz were characterized in the temperature range of 24 to approximately 1000 °C using the cavity perturbation technique. It is shown that the relative dielectric constant of silicon dioxide at both frequencies remains almost unchanged below 500 °C, above which there is a slight increase of 2%. The relative dielectric loss factor of silicon dioxide exhibits a strong temperature dependence above 500 °C and increases by approximately 7 and 5 times at 915 and 2450 MHz, respectively. The substantial increase in the relative dielectric loss factor is mainly attributed to the enhanced dielectric polarization and accelerated electrical transport in silicon dioxide at elevated temperatures.IntroductionSilicon dioxide (Si02) is usually considered a microwave transparent material due to its poor absorption capability at room temperature [1]. This characteristic has led to various applications of silicon dioxide in microwave processing of materials and communication. For instance, Si02 has been used to produce sample holders for microwave heating and substrates for electronic devices [2,3]. These applications generally require the material to withstand high temperatures under microwave irradiation. This indicates that microwave absorption capabilities of silicon dioxide at elevated temperatures are also important for its utilization.The microwave absorption capability of Si02 can be determined based on dielectric characterization (permittivity measurement) of the material at commonly used microwave frequencies, 915 and 2450 MHz, in a broad temperature range. To date, however, no detailed work on the dielectric properties (permittivity) of silicon dioxide at high temperatures has been reported. The present work is aimed to study the dielectric properties of silicon dioxide from room temperature to approximately 1000 °C at 915 and 2450 MHz. The results show that the permittivity of silicon dioxide has a strong temperature dependence above 500 °C, suggesting a substantial increase in its microwave absorption capability."

Jan 1, 2013

By Ian Masters, A. R. Khoei, D. T. Gethin

This paper describes an experimental investigation into the effects of process parameters on product quality during an aluminum recycling process. In order to build a model relating recovery to the process parameter variables and then use the model for prediction, process optimisation, or process control, a historical data analysis is employed by observing patterns in the datalogged information at IMCO Recycling Ltd. In previous work, we emphasised the importance of expressing the results of an experiment quantitatively, by implementation of a Taguchi approach, to facilitate understanding, interpretation and implementation. This research presents the technical tools that are needed to achieve quality improvement in recycling of aluminum. In this study we apply the use of historical data matching through a Taguchi orthogonal analysis, in order to control and improve the quality characteristic. For this purpose, a numerical model is developed to characterise the inputs and outputs of the process. A response surface methodology (RSM) is employed to find a suitable approximation for the true functional relationship between response and the process parameter variables. The method of least squares is used to estimate the approximating polynomials. Subsequently, Taguchi's method is used to determine the relative significance of each of the parameters. Finally, process management software (written in Visual Basic) is described, and its interface with the process modelling and optimisation routines is discussed.

Jan 1, 2000

By A. A. Bustos

Four Air Liquide Shrouded Injectors (ALSI ) were installed and operated for over one year in a Peirce-Smith converter at the Falconbridge nickel smelter in Falconbridge, Ontario, Canada. A shrouded injector consists of an inner pipe and an annulus, through which high oxygen enriched air and nitrogen flow, respectively The nitrogen cools the injector and protects the refractory in the vicinity of the injector tip, allowing for substantial increases in oxygen flow rates to the converting reactions. Several injector designs were tested to study the effect of changes in the cross-sectional area and changes in the entrance geometry of the annulus. An optimum design would minimize the injection pressure required for a given flow rate to achieve choked flow conditions at the tip of the injector. The operation of the ALSI was simple and did not require any special care or maintenance, either between blows or between converter cycles. In particular, the shrouded injectors did not require punching, as is the case with conventional tuyeres. In terms of refractory performance, the ALSI, operating at 30-40 % oxygen enrichment, were superior or equal to the conventional tuyeres, which operated at 21-23% oxygen. The results of the demonstration program led Falconbridge Limited to implement the ALSI technology on a commercial scale The paper presents the demonstration program results in terms of gas flow rates, accretion formation, punchless operation and refractory wear.

Jan 1, 1999

By M. Kawakami

In order to make titanium ingot directly from molten slag, the metal pool was tried to form and used as the cathode. The electro-slag remelting (ESR) unit was used for the purpose. The unit is composed of water-cooled copper mold and the DC power source of 2000 A and 100V. The graphite electrode was used for anode and the base plate was used for cathode. The commercial and re-melted slag of CaO-CaF2 was melted in the mold with the addition of TiO2. The following reactions are expected to occur. Ti4+ + 4e = Ti at cathode 2O2- + 2C = 2CO + 4e at anode During the process, large amount of molten slag splashed out from the mold, showing the CO evolution at anode. The metal deposit was obtained but in the form of block and piled up on the base plate. The metal pool was not obtained perfectly because of shortage of heat supply. The cathodic current efficiency was 60 % at maximum. The metal deposit contained much impurity. In order to reduce the impurity and increase the current efficiency, the effect of electrode distance was examined. The electro-slag re-melting of titanium was tried in order to examine the condition to make metal pool.

Jan 1, 2006

By Robert T. Oxnard

"EXECUTIVE SUMMARYThe history of Refractory Recycling indicates there was little recycling until the 1950s. Energy incentives were the primary reason for the beginnings of a recycling effort by the refractory brick manufacturers. Quality benefits quickly became evident and fewer rejects were the result. Today, economic factors including higher valued raw materials and increased competition are the driving forces of refractory recycling.There are some success stories in refractory recycling but we have a long way to go. Few incentives, quality concerns, relatively cheap energy, comparatively lax government regulations, inexpensive landfills and inexpensive substitutes make recycling a difficult choice for many companies. Marketing advantages such as ISO 14000, eliminating multiple audits and reduced liability exposure can tip the scales toward recycling viability. Increasingly, the ideological philosophy of a company, a desire to minimize environmental impact and develop favorable public and other interested party perceptions can drive recycling and waste minimization efforts.Recycled materials can be more trouble ""up front"" and harder to ""manage"" due to their suspect quality. However, due to their nearly inexhaustible supply and the fact that once developed, they constantly contribute to the bottom line, they are certain to be the materials of the future. Waste refractory materials will likely see the same bright future as the steel scrap yards and slag piles of yesterday. In hindsight, we will realize that now was the perfect time to prepare and plan for the bright future of refractory recycling."

Jan 1, 2000

By Ana Bohé

Nowadays, Gas-solid processes are widely used in the industry. The chloration and carbochlorination of metallic compounds are some of this kind of non catalitic heterogeneous reactions. In particular those related with extractive metallurgy of refractory elements (Zr, Ti, Nb, Ta, RE, etc). The development of materials to be used in reactors at elevated temperatures and with high corrosion performance, enhance the application of this kind of processes. Although they are currently carried out in the production of many comodities, the mechanism of most of them are yet not well understood. The present work is a deep discussion on the most important aspects to take into account for determining the mechanism of gas- solid reaction, and those criteria fulfil in this analysis were applied to chlorination and carbochlorination examples. The microstructural characteristic of solids, the mass and heat transfer phenomenon, the adsorption and desorption of gaseous species on active surface, surface diffusion processes and chemical elementary steps, which are the mainly contributions to the mechanism of these reactions were analysed. Furthermore, the effect of them on the reactivity of solids and the control step of the reactions were determined. The application of catalitic mathematical models to this kind of reaction and the modification for the better interpretation of experimental results is also undertaken. The most appropriate experimental procedures for following these reactions and the microstructural characterization techniques needed to be use in each case, there limits and applicability are also indicated.

Jan 1, 2006