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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 Hani Henein

"Heat transfer between droplets/particles and a gas phase plays an important role in the transport of numerous materials processing operations. These include rapid solidification operations such as gas atomization and spray forming, as well as chemical systems such flash furnaces. Chemical reaction rates and solidification are dependent on the rate of gas-particle or gasdroplet heat transport. Using a heat transport model validated using single fluid atomization of molten droplets; the effect of process variables on heat losses from droplets was examined. In this work, the effect of type of gas, droplet size, gas temperature, gas-droplet relative velocity on the heat transport from AA606 l droplets was examined. The most critical of these process variables to heat transfer is identified and will be presented.IntroductionIn materials processing, droplets are often encountered and used in processing a wide range of liquids and slurries. The small size of the droplet enables high reaction rates or high solidification rates in many systems. In order to capitalize on these high rates of transport processes, sprays are· also developed to maximize throughput. The design of these sprays, however, does not account for the transport steps and rate limiting mechanisms at the droplet surface. Rather, spray design focuses on maximizing the break-up of a stream or slurry into small size droplets or controlling the spread of the spray. Spray systems in industrial use typically generate droplets of wide size distribution leading to a wide range of reaction times for each of the droplets. Often the generation of a spray involves a number of coupled phenomena such as stream break-up, droplet-gas transport, droplet size distribution and spray geometry. Using gas generated sprays, it is not possible to identify how individual process variables contribute and control each of these coupled phenomena. While many mathematical models have been developed of sprays and they attempt to simulate coupled droplet transport, they do not provide insight into the contributions of different mechanisms in heat transfer. This is primarily because the basic fundamental heat transport between droplet and gas cannot be isolated from other gas spray phenomena experimentally such as two-way thermal coupling [l]. Thus, experimental validation of heart transfer of large and complex industrial spray models is not carried out. Hence, the validity of spray models remains in question and the approach required to optimize spray processes cannot be clearly identified"

Jan 1, 2004

By Hidekazu Nakagawa

We investigated the anodic dissolution behavior of titanium in TMHA-Tf2N molten salt, which has a wide electrochemical window of about 5 V, in order to develop an electrodeposition method for titanium. By etching a titanium electrode in HF?HNO3?H3PO4 solution, the titanium electrode became electrochemically active, and a redox reaction was observed at around -0.15 V vs. I-/I3- in (TMHA-Tf2N)?HTf2N solution. We identified the redox reaction consists of the reduction of the proton and the oxidation of hydrogen. The diffusion coefficient of the proton in TMHA-Tf2N was calculated to be 6.9 10-8 cm2 s-1 at 50 °C from the cathodic peak current in the cyclic voltammogram. Anodic decomposition of the molten salt was not observed up to 6.0 V vs. I-/I3- on titanium electrode, while it was observed at around 2.0 V vs. I-/I3- on platinum and glassy carbon electrodes. Cathodic decomposition of the molten salt was observed at around -3.0 V on the titanium electrode, as well as on the platinum and glassy carbon electrode.

Jan 1, 2006

By M. Misra

The finely dispersed kerogen particulates present in the dilute suspension can be coagulated with the aid of a hydrophobic organism, Mycobacterium Dhlei. The initial coagulation and aggregation are strongly dependent on pH and organism concentration, the isoelectric points of oil shale kerogen and Mycobacterium phlei are at pH 3 and 1.8 respectively. As a result the aggregation is rapid around pH 3. Preliminary results show that it is quite possible to use microorganisms for enhanced dewatering of kerogen concentrate produced by froth. flotation.

Jan 1, 1991

By Huanyu Zhang, Zhancheng Guo, Liqiang Fan, Huiqing Tang

"In this study, a simple process has been developed for zinc oxide recovery from RHF (rotary hearth furnace) secondary dust. The results have shown that a high dissolution efficiency of soluble zinc was achieved with water leach at ambient temperature with a liquid/solid ratio of 10/1 in 30min while 20% of the dust was left as solid residue. The rate of dissolution increased slowly after the dissolution efficiency reached 90%. The leaching process was found to be controlled by external diffusion. After separation, zinc was precipitated in leached liquor by introducing a precipitation agent of potassium hydroxide. The resulting solid was purified and dried at 393K. Zinc powder in the form of ZnO with purity of 98.5 mass% was obtained with an average size of 12.4µm.IntroductionThe RHF (rotary hearth furnace) direct reduction process is widely used in many iron and steel enterprises to deal with various metallurgical dusts [l]. The basic principle of this process is that first various metallurgical dusts (BF dust, EAF dust and so on) are pelletized with a coal reductant, and they are then subjected to a fast reduction using RHF after being dried. Highly metallic pellets are produced and at the same time, nonferrous elements such as Zn, Pb, K and Na are evaporated into the RHF flu gas as secondary dust. Zinc is listed by the Enviromnental Protection Agency as one of the 129 priority pollutants. Therefore, recovering zinc from the industrial wastes is important in terms of enviromnental protection [2-3]. On the other hand, nowadays China is in shortage of zinc resource and the annual output from metal recycle only accounts for some 13% of the total zinc resource. There are many ways proposed to recover zinc from various wastes [ 4-7]. The aim of this paper is to recover zinc oxide from RHF secondary dust by a method with water leach followed by caustic precipitation. This work investigated the influence of the leaching temperature and leaching liquid/solid ratio on the zinc recovery efficiency. The process consisted of three stages: (1) leaching with water; (2) liquor/residue separation; and (3) zinc precipitation in caustic milieu."

Jan 1, 2014

By Truan-Sheng Lui, Li-Hui Chen, Hao-Wen Hsueh, Fei-Yi Hung

"Since Ag wires have similar hardness and bonding properties to Au wires, they can be applied in some pads. In the present study, the annealing effect (at 225°C~275°C for 30min) on the tensile mechanical properties of silver wires with f=23µm was investigated. In addition, the micro-structural characteristics and the mechanical properties before and after an electric flame-off (EFO) process were also studied. Experimental results indicate that with annealing temperatures of more than 250°C, the silver wires possessed a fully annealed structure, the tensile strength and the hardness decreased, and the elongation was raised significantly. Under the thermal effect of EFO, the necks of the Ag balls underwent recrystallization and grain growth was induced, and the annealed Ag wires had a shorter zone of HAZ (220µm). The bonding strength and the neck-strength of the Ag wires were more than 7gf and possessed excellent bonding properties.IntroductionThermosonic ball bonding is one of the preferred processes for electronic packaging to connect a semiconductor chip and a lead frame by a thin metal wire. At present, gold wire and copper wire are the preferred interconnect materials to bond with the aluminum metallized wafer pads [1, 2]. Since gold is expensive and the reliability of copper is poorer [3], the study of silver wire has attracted a lot of attention already. In addition, the inherent properties of high ductility and low hardness of silver as well as its workability effectiveness compared to gold, have made it a preferred alternative .[4, 5]"

Jan 1, 2012

By Selvin Yesilay, Munevver Caki, Canbora Bayraktar, Bekir Karasu, Rahmi Imrak

"In this study, the utilization capability of the solid wastes taken from a commercial roof tile and brick factory in Eskisehir of Turkiye has been investigated in the production of stoneware bodies which can be formed by slip casting. At the first stage, X-ray fluorescent (XRF) and X-ray difractometer (XRD) analyses of the wastes were performed. Depending upon the results, a body recipe with an optimum casting concentration was adjusted. The bodies obtained from prepared slips were fired at 1160 oC as glazed and unglazed forms. Then, they were undergone certain tests in order to determine their firing shrinkage values, water absorption levels and optical parameters. To establish what kind of phase formations occurred after firing as a result of waste incorporations into bodies XRD analysis was conducted. Additionally, effects of such a compositional modification on the microstructure of the bodies were examined by a scanning electron microscope (SEM). Consequently, it was concluded that fired roof tile and brick wastes could be evaluated in both glazed and unglazed stoneware bodies. Introduction Stoneware is the general name applied to many wares fired between 1150 and 1300 °C. It has a different and denser structure than those of ceramics produced at lower temperatures. Fired stoneware possesses a lower water absorption value. When matured at a high temperature, it gives a possibility for the use of feldspar as a main ingredient [1-2]. Colors of stoneware can be brown, red, white and most of the times beige. Firing usually takes place in oxidation atmosphere but also reduction can be rarely used. This naturally has an effect on the body colors [3]. Earth, which contains clay minerals, becomes plastic mud when mixed with water, has a capability to be easily shaped and can be hardened without cracking if fired at 900-1000 °C, is referred as one of the brick and tile raw materials [4]. Natural and aesthetic appearances of buildings obtained with brick and tile products, which make them preferable especially for construction sector, are of importance. Because clays being main raw material of that type of productions generally do not exist as pure materials in nature, their usability depends on their mineralogy and impurities they contain [5]."

Jan 1, 2008

By G. J. Shiflet

This paper will review work done in our laboratory on the formation, thermodynamics and crystallization of aluminum based metallic glass with the addition of rare earth elements. The results demonstrate that the metallic glasses are truly amorphous and not microcrystalline and that they are unusual in their formation because the alloys contain 90 at. % aluminum and there is no deep eutectic present in the phase diagram. Tensile strengths that exceed 900 MPa are obtained for several of the compositions and exceed 1000 MPa after partial crystallization.

Jan 1, 1992

By Du Sichen

The present paper presents the modeling of gas-solid reactions in the case of the decomposition of CaCO3, describing the reaction kinetics on the basis of heat-transfer concepts which could be compared with thermogravimetric results. In the case of solid-solid reactions, the present paper describes the model developed for describing solid-solid reactions from dynamic X-ray diffraction technique, developed by the present team. The model has been successful in explaining the formation of spinel from MgO and Al2O3.

Jan 1, 2006

By Hongmin Zhu, Qiuyu Wang, Shuqiang Jiao, Guojing Hu

"The equilibrium between titanium ions and metal titanium was investigated in fluoride-chloride molten salt. The electrochemical properties of titanium ions in fluoride-chloride were studied on a molybdenum electrode by cyclic voltammetry (CV) and square wave voltammetry (SWV). The equilibrium constant of the equilibrium between titanium ions and metal Ti was calculated in KCI-NaCl- 2.5wt %K2 Tif 6 at the temperature of 1073K.IntroductionTitanium, the ninth most abundant element in the earth's crust, is endowed with high strength, low density, excellent flexibility, strong spring back characteristics, high-temperature performance, corrosion resistance and biocompatibility. These characteristics make titanium eminently suitable to be used in aerospace, marine industries, and harsh chemical environments. Although it has many excellent properties, the application of titanium in industry was limited by its high-cost. Therefore, many methods have been investigated for producing high-purity titanium at low cost. Electrolysis, involving the extraction and preparation of pure metal from ore using an electrolytic process, is considered a promising method for titanium metallurgy. Many studies have focused on the electrochemical behaviour and electrodeposition of titanium in molten chloride, fluoride, and chloride-fluoride electrolytes (1-IOJ. The electroreduction mechanism of Ti3+ ions in molten alkali chlorides has previously been studied by several workers. Two reduction steps, Ti3+ -Ti2+ -Ti, have been observed in various molten alkali chlorides [IJ. One reduction step, Ti3+ -Ti, has been observed in alkali fluoride molten salts l21. The behaviour of Ti4+ in fluoride or chloride-fluoride molten salts has also been investigated in the literature; it was proposed that the reduction of Ti4+ ions in the molten salts proceeded in a two step process: Ti4+-Ti3+-Ti l3l or a three step process: Ti4+ -Ti3+ -Ti2+-Ti ri. 4l Indeed, the stability of the titanium oxidation states depends on the bath composition l5l. The valence state was Ti2+ in alkali chloride melts, which was a lower oxidation state and correspondingly, in alkali fluoride melts, the higher oxidation states ofTi4+ and Til+ were more stable.The aim of the present work is to explore the effect of F/Cl atomic ratio on the equilibrium between titanium ions and metal titanium in fluoride-chloride at the temperature of 1073K. The electrochemical properties of titanium ions in fluoride-chloride were studied on a molybdenum electrode by cyclic voltammetry (CV) and square wave voltammetry (SWV). The solubility product of the equilibrium between titanium ions and metal Ti was calculated."

Jan 1, 2012

By Susumu Okabe

The Mitsubishi Continuous Copper Smelting/Converting Process employs an electric furnace for settling the slag/matte mixture formed in the smelting furnace. In order to improve the separation of slag and matte and to minimize power consumption, the design and the operating conditions of the electric furnace should be optimized. As the first step, numerical heat and fluid flow analysis of the melts was carried out based on the distribution of current density and Joule?'s heat obtained by the electric field calculation. For these calculations, 3-D body fitted coordinate system and a finite volume method were applied. Using the developed numerical model, the flow pattern analysis by pulse input of a tracer element was simulated. It was found that a strong thermal convection of the molten slag exists around the electrodes due to the concentrated Joule's heat generation in a small area just under the electrodes, and this strongly affects the flow pattern in the furnace. The calculation results were compared with the data obtained from 'a plant test.

Jan 1, 1998

By Ian Masters, Saul B. Davies, David T. Gethin

The purpose of this model is to simulate and analyze the energy flows within a rotary aluminum recycling furnace, using the global properties of its main components, the gas, metal and refractory walls. The model will simulate a series of operations such as loading, heating and stirring which will constitute the processing of a batch. Each main component of the furnace is treated as a one-dimensional heat transfer medium, the thickness and area of each medium being calculated from the actual geometry of the furnace. The physical properties are taken as the weighted average of those for the various layers forming the medium. Incorporated into the model are elements describing the radiative exchange within the furnace, melting of the charge, and forced convection in the melt due to the rotation of the furnace. This approach has produced a model with a reasonable computing time that can be used to run a whole series of simulations for the prediction and comparison of the furnace performance under different operating conditions.

Jan 1, 2000

By L. B. Tsymbulov

At present data on thermodynamic properties of metallic melts, containing copper and ?iron family? metals, is rather limited. Determination of the activity of metallic melts components under high temperature by experimental methods requires high level of labour inputs. With this it is not always possible to obtain the results with high level of accuracy. Due to that in a number of cases it is more appropriate to apply different methods of analysis, with the help of which there can be calculated thermodynamic properties of ternary and even more complicated systems, prominent thermodynamic properties of binary systems being used as a basis for these calculations. This work presents the results of calculations of different components activity and activity ratio in such ternary system melts as Ni-Cu-Fe, Ni-Cu-Co, Fe-Cu-Co and Fe-Co-Ni. Good compliance of calculations results with those obtained in the course of reliable experimental investigations fulfilment is demonstrated. There are presented the results of activity and activity ration analysis for some compositions of Cu-Ni-Co-Fe system.

Jan 1, 2006

By S. F. Cheng

Among the many extraordinary features of the rare earths are their magnetic and magnetoelastic properties. The rare earths, e.g. Tb, Dy, Nd, Sm, are known worldwide for their large magnetocrystalline anisotropy and magnetization, which has led to the importance of magnetic rare earths as vital ingredients of modem permanent magnets. In this paper, we focus on the strain dependence of these giant effects which gives rise to huge magnetostrictions, magnetomechanical couplings, and ?E effects. Magnetostrictions greater than 10-3 have been measured at temperatures as high as 500 K. At low temperatures magnetostrictions reaches -1%. ?E effects - 10. No other solid state material has matched these values. A proper balance of magnetic anisotropy and magnetostriction, plus a proper choice of crystal axes lead to alloys which can switch large quantities of energy between the internal (magnetic) and external (mechanical) states with the application of small triggering magnetic fields. In addition to the traditional use of these materials in transduction, they are particularly valuable for smart systems where reliability and robustness are needed such as active structure stiffening and active vibration control.

Jan 1, 1997

By Robert W. Hyers

Electromagnetic levitation has proven important in a wide range of experiments, all affected by fluid flow. For some experiments such as viscosity measurements, only whether the flow is laminar or turbulent must be established. For other experiments, however, quantitative assessments of velocity, shear stress, or shear strain rate are required. In most cases it is difficult or impossible to measure the internal flow in levitated droplets directly. The samples are usually small, opaque, reactive, high-temperature, metastable, or all of these. Furthermore, recirculating flow limits the utility of tracking surface particles, since they collect in stagnation points ratherthan following the flow. Most research groups have chosen mathematical modeling to assess the internal flow in levitated droplets. A variety of analytical and numerical methods have been applied, including both laminar flow and various turbulence models. A number of these models are reviewed and their impact on different containerless experiments is assessed. Much of the research reviewed here was performed by alumni of Professor Julian Szekely, and by others using similar methods.

Jan 1, 2006

By Kongfang Feng, Fei Ruan, Zhiyu Liu, Jieyu Zhang, Xin Hong, Shaobo Zheng, Jixu Wang, Jinyin Xie

"Mixing phenomena in smelting reduction furnaces with asymmetric side blowing were studied in this paper. Mixing phenomena in a smelting reduction furnace was represented as the mixing time by electrical conductivity measurements. Experiments were performed in a water model under various operating conditions to determine the effects of horizontal angle, radial angle, inserting depth, flow rate of the upper and the lower side nozzle, the included angle between the upper side nozzle, and the lower side nozzle on mixing phenomena in smelting reduction furnace. Comparing mixing time and mixing phenomena, the optimal conditions were obtained for an asymmetric side blowing process.IntroductionIn recent years, many countries have put forward development strategies for saving resources and environment-friendly, the development of various industries had to face its influence for resources and the environment .As we all know, the steel industry is a pillar industry of the global economy, in which ironmaking is an important part of it. In the modern ironmaking process, the blast furnace is regarded as the most important equipment and tool. But with the increasing scarcity of metallurgical coke resources and considering the environmental impact of such processes, metallurgists proposed the concept of smelting reduction. Smelting reduction processes to produce hot metal from iron ore and coal were being developed as a possible alternative to the traditional blast furnace. At present, a number of smelting reduction processes had been developed all over the world, they were mainly included COREX, HISMELT, FINEX, DIOS, etc."

Jan 1, 2012

By Jing Zhang, Chenguang Bai, Fusheng Pan

"The microstructure and hot deformation behaviour of an Er-modified Mg-Zn-Ai alloy were evaluated. The results showed that the addition of rare-earth Er changed the morphology of the quasi-continuous grain boundary networked eutectic compound to globular particles. Moreover, a self-strengthening effect was identified for the alloy, which determined its deformation behavior. After hot extrusion, the yield strength and elongation to failure of the Mg-Zn-AI-Re alloy at 200°C were increased by 105% and 120%, respectively, due to an emerged dynamic precipitation strengthening mechanism.IntroductionMagnesium alloys are attracting increasing attention for applications in automobile, electronic devices and hand tools for weight reduction and higher fuel efficiency, because of their lightweight and a high specific strength. However, application of Mg is still very limited. The largest applications are still those non load-bearing castings used at room temperature, such as box case, housing, and covering. One of the main reasons is the inadequate absolute strength both at room temperature and elevated temperatures (> 100°C) of the commercially used AZ, AM series alloys, due to the incoherent interface between the secondary phase y-Mg17AI12 and Mg matrix, as well as the low thermal-stability of the y phase [1]. Besides, the heat-resistant magnesium alloys which contain rare earth (Re) as the main alloying element are very expensive. The other reason is their poor deformability. The key solution is therefore to develop low-cost heat -resistant wrought alloys."

Jan 1, 2012

By V. Kamavaram

Ionic liquids are novel salts used as potential non-aqueous electrolytes for aluminum electrolysis at low temperatures. In the current research di-alkylimidazolium chloride ionic liquids such as 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) and 1-hexyl-3-methylimidazolium chloride ([HMIM]Cl) were investigated for aluminum electrolysis. Melt formed by mixing ionic liquid with AlCl3 is termed as chloroaluminate and is composed of several polymeric chloroaluminate anions. Ionic liquids are studied as electrolytes for aluminum electrowinning and electrorefining of aluminum based materials (A356, A360, & Al-MMC) at low temperatures. Mechanism of aluminum electrodeposition in these chloroaluminate ionic liquid electrolytes was investigated using electroanalytical techniques such as cyclic-voltammetry and chronoamperometry. Aluminum electrodeposition on pure copper substrate in AlCl3-[BMIM]Cl (1.5:1.0) electrolyte at 30°C melts was found to be quasi-reversible process with a charge transfer coefficient ( of 0.40. Chronoamperograms obtained at different voltages in the range (-0.1 to -1.0 V) revealed that the initial stages of aluminum deposition in AlCl3-[BMIM]Cl melts was instantaneous nucleation followed by diffusion controlled growth of three-dimensional aluminum nuclei. The diffusion coefficient of electroactive species Al2Cl7¯ in AlCl3-[BMIM]Cl melts was found to be 6.5×10-7 cm2 s-1 from Cottrell?s equation and 3.9×10-7 cm2 s-1 from the dimensionless current-time transients.

Jan 1, 2006

By Laurentiu Nastac

"Two advanced control solidification technologies were studied in this article to improve the quality of the cast ingots as well as to control the solidification structure evolution during the plasma arc melting (PAM) processing of Ti-6-4 ingots: (i) electromagnetic stirring (EMS), and (ii) ultrasonic treatment (UST). The developed EMS modeling approach is based on the numerical solution of Maxwell's equations, fluid flow, and heat transfer equations, and mesoscopic modeling of the grain structure. The UST analysis tool is capable to model acoustic streaming and cavitation. It is used in this work to study ingot solidification under the presence of ultrasound. Predictions of the macrostructure, GET formation and primary dendrite arm spacing for PAM Ti-6-4 ingots processed with and without EMS or UST were discussed.1. IntroductionTitanium (Ti) alloys are melted, refined and cast into ingots through plasma arc cold hearth melting (PAM), electron beam cold hearth melting (EBM) and vacuum arc remelting (VAR) for jet engine applications. Process modeling has become a viable tool to optimize the PAM, EBM, and VAR processes. A comprehensive modeling approach to simulate ingot solidification phenomena in primary melting and secondary remelting processes of Ti alloys would include models for macroscopic mass transfer, heat transfer, fluid flow, acoustic, electromagnetic and species transport. The approach should also include microscopic models to predict the evolution of grain structure in solidifying ingots in conjunction with electromagnetic stirring (EMS) and ultrasonic stirring (UST)."

Jan 1, 2012

By Pertti Pekkala

Outokumpu has 25 years of experience in the SX area. The development of the solvent extraction plants responds to an ever increasing demand for lower operational costs wd for adaptability to process disturbances with minimized risks. In this paper the features of the VSF ("Vertical Smooth Flow") SX technology are described, such as the separated pumping and mixing, the homogenous gentle mixing, the droplet coalescence and the ultra pure settling. A major advantage of the mixing technology is the high stage efficiency of above 99 per cent. The connection between this and some features of the settler front section is clarified. The present design of VSF plants is based on experience of existing operations at, for example, Zaldivar, Radomiro, Morenci, Kokkola and Harjavalta. These production plants cover a unit capacity range of 60 to 3,600 m3/h expressed as a total flow. It is evident that there are no restrictive factors to increase the total flow up to 5,000-6,000 m3/h by introducing the VSF technology. The copper SX technology has a long history reflecting many individual features of the separate copper SX plants. Still it is necessary to verify all actual running parameters by pilot tests taking into account impurities, chemicals used etc. The design of SX plants is not only about the delivery of equipment but also a process concept, and it is best tailor-made and adapted to specific local requirements.

Jan 1, 1999