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By W. Dresler

Design details of a 100 kVA DC electric-arc reduction furnace are described. The furnace is equipped with a 610 mm (24 inch) diameter graphite crucible hearth. A 76 mm (3 inch) diameter top graphite electrode is used as a cathode. The current passes through the bottom of the crucible and is carried to a bottom plate (the anode) by conductive magnesia carbon bricks. The furnace can be operated up to a maximum of 120 V, 1800 A, and presently 100 kW. The start-up operating experiences and metallurgical results of one reduction test with a Montana chromite containing 38% Cr2O3 are discussed.

Jan 1, 1994

By Yuanbo Zhang, Huanpeng Mi, Guanghui Li, Binjun Liang, Zhiwei Peng, Tao Jiang

Ludwigite ore has not yet been utilized on an industrial scale due to its complex mineralogy and fine mineral dissemination. In this study, sodium salts were employed to enhance the separation of iron and boron by reductive roasting-magnetic separation. It was found that the separation of iron and boron as well as the iron grade and recovery were significantly improved b y the addition of Na2SO4 or Na2CO3. Under the reduction temperature of 1050 °C, reduction time of 60 min and magnetic intensity of 0.1T. Compared with the inexistence of sodium salts, the iron grade and recovery of the magnetic concentrate increased from 83.3% and 88.6% to 93.2% and 95.1%, respectively, by adding 6% Na2CO3. The XRD and microstructure analyses indicated that the iron oxides were transformed into metallic iron and the average metallic iron grains were grown to over 40μm which was beneficial for separation of metallic iron from gangue.

Jan 1, 2016

By Hiroshi Tabuchi, Akihiko Takahashi

"High strength aluminum matrix composites were prepared and studied using as reinforcement newly developed nearly mono-dispersed a-alumina single crystal particles each of which has a regular polyhedral shape. The composites were formed by centrifugal casting using aluminum casting alloys (Al-Si and Al-Cu-Mg) as the matrices, followed by heat treatment. The volume fraction of the alumina particles was as high as 60%. The same matrix composites reinforced by conventional crushed fused alumina particles were similarly prepared as the reference. The bending strength and tensile strength of the Al-Cu-Mg matrix composites reinforced by the novel alumina particles of 10 µm in average diameter are as high as 1020 MPa and 560 MPa, respectively, which are higher than those of the conventional alumina composites. Furthermore, the bending strength of the novel alumina composites degraded less than that of the conventional alumina composites after thermal fatigue tests. The number of cracks in the matrix seemed to influence the thermal fatigue property because many cracks were observed in the conventional alumina composites, whereas only a few cracks were observed in the novel alumina composites. This was confirmed by SEM observation of the sample composites before and after the thermal fatigue tests.IntroductionAluminum matrix composites strengthened by dispersed reinforcements are of interest for various applications due to their improved properties, such as high specific strength and stiffness, wear resistance, etc .. A large number of investigations have been made concerning fabrication processes and properties of these composites. With regard to the fabrication processes, powder metallurgy has been well-known as a solid phase process, and recently many liquid phase processes such as a compocasting, a squeeze casting, the Lanxide process, and the Osprey process have been studied and developed.(1)"

Jan 1, 1998

A strategy is presented for a relatively. "low-tech" means for decontamination of streams . containing .low concentrations of toxic metals. Metal ion solutions were . circulate through fluidized beds of activated carbon which support bio-films ?of bacteria .that naturally excrete exopolysaccharides. The attached 'biomass is shown to significantly enhance nickel, cadmium and silver extraction from dilute solutions (5- l00mg/l). By heat treating (at 300º C) the metal/biomass/carbon particles, bio-sorbed silver was subsequently fixed to the carbon surface. This approach to metal decontamination may therefore also provide a route for dispersing and fixing catalytic metal particles over an activated carbon surface.

Jan 1, 1991

By K. R. Robilliard

Ausmelt Technology has been developed to process copper concentrates containing significant levels of lead, arsenic and antimony. A process was developed aimed at smelting these concentrate materials to remove the contaminants to fume and produce a clean copper product. The production of clean copper and the potential economic benefits of this process step over the sale of impure concentrates is discussed.

Jan 1, 1995

By Y. Fukunaka, M. Niinae, E. Kusaka, T. Kuzuya, R. Ishii

"Samarium oxalattr particles was precipitated in oxalic acid aqueous solution from samarium-loaded D2EHPA solution emulsified with a conventional impeller. The calculated fractional precipitation of samarium oxalate was reasonably compared with the value determined by chemical analysis. Morphological variation of oxalate precipitate particles was then examined with H2C2O4 concentration in aqueous solution, Sm(III) and D2EHPA concentrations in organic phase. The needle-like precipitate was identified as Sm2(C2O4)3 10H2O by XRD. Precipitates obtained at higher H2C2O4· or Sm(III) concentration greatly decreased the length of major axis of precipitate, while those at higher D2EHPA concentration increased it. The oxalate was further precipitated under ultrasonic irradiation. However, the morphological variation caused by theses processing variables was not so evident under ultrasonic irradiation as in an impeller or shaking mixer.IntroductionThe materials processing of the rare earth elements must be reviewed from the scope of industrial ecology, since they have the potential applications of magnetic materials as well as secondary battery in developing programs of the electric vehicle. The technological trend to develop the electric vehicle may greatly influence the concept of materials processing, since the global· environmental problem must accommodate with the sustainable development for mankind. The recycle design must be a key issue in the materials science and engineering.Solvent extraction provides a unique separation technology -in this sense. Doyle (1)(2) reported the integrating solvent extraction with processing of advanced ceramic materials, whose chemical composition and microstructure must be precisely controlled. In her paper, the higher productivity inherent to the present process superior to hydrolyzing metal alkoxides was emphasized. Oxalic acid has been used as precipitant for rare earth purification process, since rare earth oxalate has a very small solubility in water and can be easily decomposed to oxide. It is thus suitable for precipitation stripping agent in cationic exchange type extracting system (i.e. D2EHPA, VA-10, PC-88A and so on)."

Jan 1, 2000

By Katsuya Kase, Kaname Takeya, Keaji Ohmori, Yoshiyuki Asakawa

"The reduction-diffusion process (the R-D process) using Ca as a reducing agent has been practiced in industry in the production of the SmCos type, the Nd-Fe-B type and the 1b-Fe-Co type magnetic materials. The advantages of the R-D process are the generally high yield of rare earth metals and the single-stage conversion of a mixture of oxides and metal powders into a product of rare earth alloy powders. On the other hand, one of its disadvantages is the slightly high contents of oxygen and calcium. This disadvantage is remarkable in the Nd-Fe-B type. Singe-phase Nd2Fe14B alloy powders with low content of 0 and Ca, is obtained by choosing appropriate raw materials and performing the R-D process in a controlled way. These alloy powders are very suitable for the production of Nd-Fe-B sintered magnets and expected higher magnetic properties by adopting advanced magnet production method.IntroductionThe hard magnetic rare earth transition metal intermetallics, especially, have attained considerable technical importance. Examples are the alloys based on the intermetallics SmCo5[1], SmC017[2], NchFet4B[3], or the recently developed alloy SnuFe11Nx[4]. The reduction-diffusion process using Ca as a reducing agent has been well known as an economical method of producing rare earth based magnet materials[5]. The reduction-diffusion process has been practiced in industry in the production of the SmCos type, the Nd-Fe-B type and the 1b-Fe-Co type magnetic materials. The advantages of the reduction-diffusion process are the generally high yield of rare earth metals, the single-stage conversion of a mixture of oxides and metal powders into a product of rare earth alloy powders, the elimination of the crushing process of the alloy ingot, the inessentiality to special equipment, etc. On the other hand, one of its disadvantages is the slightly high content of oxygen and calcium. This disadvantage is remarkable in the Nd-Fe-B type. An outline of basic studies of the reduction-diffusion process was reviewed from the particular viewpoint of the production of magnet materials by Ogawa [6]."

Jan 1, 1998

By Dhanesh Chandra

In this symposium, research in the area of energy conversion is presented. This symposium has special significance, as we honor three prominent scientists from hydrogen storage research and development field. In this symposium, the majority of papers presented by international scientists and engineers are in the area of hydrogen storage. Other energy conversion papers include magnetic materials, superconductors, and thermal energy storage materials. Recent developments in light-weight high gravimetric hydrogen density hydrides have led to potential use of hydrides for onboard automobile and other applications. This, of course, is significant from environmental concerns of CO2 and other emissions from the current use of carbon based fuels in automobiles. Thus, it is becoming increasingly important to switch to cleaner alternative fuels such as hydrogen [1]. The Challenge of Vehicular Hydrogen Storage as potential hydrogen energy carriers for vehicular applications, with a driving range of approximately 300 miles, require ~5-13 kg of hydrogen stored on-board. In the United States, Centers of Excellence have been established in metal hydrides, chemical hydrides, and carbon-based materials, and abundant scientific and industrial research is being carried on metal hydrides; only some of the current research from the Centers will be reported here. The European commission, Japan Institutions, and others also have numerous hydrogen storage programs in progress. Several international collaborations have also begun between IEA and IPHE scientists to accelerate the progress of development of practical hydrides. A summary of the abstracts is included in this overview.

Jan 1, 2006

By J. R. Rendón

Cylinders of commercial aluminium alloy 6063 were homogenized under different conditions. The experimental results indicated that the general mechanical behaviour as related to curves of 0.2% yield strength, ultimate tensile strength and Brunnell hardness versus homogeneizing process is the same in both cases. The mechanical properties as compared to those required by plant specifications, tend to be better with increasing values of % Mg2Si in the alloy, as expected. The electron microscopy investigations revealed that in both homogeneizing processes the resulting microstructure consist of significant spheroidizing of the alpha phase (AlFeSi) and fine-needle type structure of beta phase. The alpha phase was also present in a Chinese type scripture. Furthermore, the slow cooling within the furnace resulted in the nucleation and growth of Mg2Si precipitates generally along the grain boundaries.

Jan 1, 1997

By Tobias Dubberstein, Hans-Peter Heller

The viscosity of Fe-Cr-Mn-Ni TRIP/TWIP (Transformation Induced Plasticity, Twinning Induced Plasticity) steel with varied nickel content is investigated using a vibrating finger viscometer. The viscosity of the melt is calculated from the change in power input in the field coil by an immersed finger into the liquid steel to maintain a constant peak-to-peak amplitude of the sine wave of oscillator compared to the idle state. Nickel content in steel is varied from 3 wt% to 9 wt%. The dynamic viscosity (η) at 1600 °C for 3 wt% Ni is 3.73±0.14 mPas, for 6 wt% Ni 3.50±0.03 mPas, and for 9 wt% Ni 3.93±0.09 mPas. There is a kink from low to high nickel content in viscosity values of Fe-Cr-Mn-Ni alloys. This phenomenon can be explained by a change in coordination number in the melt, as reported for Fe-Ni binary system in literature. The availability of viscosity data delivers relevant input to model free fall atomization processes of FeCrMnNi alloys.

Jan 1, 2015

By Tadashi Aiura, Yasuhiro Miura

"A small amount(0.2mass%) of Scandium(Sc) was added to the 7.NOl and 5083 Al alloys as a refiner and stabilizer of microstructure, and the resulting microstructures were discussed in comparison with the effects of the conventional additives. The followings are summarized: 1) in the as-solidified structure, a ·decreased tendency of constitutional supercooling and increased solubility of Mg were recognized for the Sc-added 5083 alloy. Sc is a -better microstructure refiner for the 7N01 alloy than Zr, in a sense that it does not suppress the favorable effect of· coexisting Ti. 2) Sc effectively suppresses recrystallization both in the 5083 and 7N01 alloys. 3) The rod like primary Al3Sc crystals formed during solidification, as well as the fine dispersion of Al3Sc precipitates formed by subsequent heat treatment, can act as a strong recrystallization suppresser. IntroductionThe 7N01 and 5083 alloys are the most popular industrial Al alloys and they are widely' used for various structures because of their superior properties. Fine macro and micro structures of the materials are required for obtaining acceptable sec resistance,consistent appearance of anodized surface and good weldability, as well as good mechanical properties. In order to produce fine grain structures, transition metals, such as Cr, Zr, and Mn, have been conventionally added.It has been reported that Sc is an efficient refiner [l, 2] and can be an alternative for the conventional and also suppresses recrystallization in Al alloys [3,4]. Scandium is the lightest transition element and forms an equilibrium intermetallic phase. The equilibrium phase, Ll2-Al3Sc, is coherent with the matrix, and of _spherical shape. A fine dispersion of the spherical precipitates is obtained by quenching and aging after solutionizing annealing. The authors have already reported a part of the experimental results on the effect of Sc on the as homogenized microstructure of the 5083 alloy [5]. In the present study, the effects of Sc on the macro and micro structures of the industrial high strength Al alloys(7N01 and 5083) for extrusion are investigated, and the superior role of Sc as a grain refiner is shown"

Jan 1, 2000

By Jiann-Yang Hwang

The economic growth in new developing countries such as China and India has stimulated strong demands in basic materials such as steel. World steel production has exceeded the milestone of a billion tons a year recently. However, the blast furnace technology, which was invented in 1340 A.D., is still the fundamental route for today?s steel production. It is important to develop a new generation of steelmaking technology that can meet the society?s needs from the energy, environmental and economic standpoints in the 21st century. The new microwave and electric arc heating technology discussed in this paper provides a totally different mass and heat transfer mechanism from the conventional blast furnace technology and offers a great potential to meet our society?s needs.

Jan 1, 2006

By Tiejun Chun, Jian Pan, Deqing Zhu, Zhiyong Ruan

"In this paper, the desulfuration of pyrite cinder pellets was carried out. Phase analysis shows that most sulfur of pyrite cinder exists in the form of elementary sulfur. Most sulfur was removed in preheating stage. 81.25% sulfur was removed and the average SO2 concentration of exhaust gas was 1365ppm when the pellets were preheated at 950oC for 9 min. The final product, assaying 62.42wt%Fe and 0.02wt%S content at 96.88% desulfuration was achieved under the conditions of preheating at 950? for 9 min and roasting at 1200? for 15 min, which can be used as the burden for blast furnace.IntroductionPyrite cinder, as a subsidiary product of sulfuric acid production by roasting of pyrite ores, was solid waste in sulfuric acid enterprises. According to the statistics, the annual production of pyrite cinder is about 15 million tons in China. Besides, there is lots of pyrite cinder deposited for many years [1-3]. The pyrite cinder consumed in the cement and other industries as auxiliary additives only accounts for less 30% of its total discharge and the left is stored in waste pond, occupying much land and polluting environment in China [4-5]. Moreover, pyrite cinder contains iron between 30-63% which can be utilized as a cheap raw material for ironmaking by sintering or pelletizing processes, which can not only prevent pollution but also provide cheap raw materials for ironmaking [6-7]. However, compared to traditional iron ore concentrate, pyrite cinder possesses higher sulfur content."

Jan 1, 2012

By M. Tangstad, H. Mølnäs, J. D. Steenkamp

"Temperature affects several aspects of pyrometallurgical systems, including thermodynamics and reaction kinetics. Reliability of temperature measurements in laboratory and plant applications is thus important from process, safety and financial perspectives. This case study briefly introduces different techniques utilized for temperature validation, and demonstrates temperature validation on laboratory scale utilizing the wire-bridge method. Pt/Ptl3Rh thermocouple hot junctions were constructed by mechanically connecting thermocouple wires through a pure metal bridge consisting of copper, gold, nickel or palladium wire. When heating the wire-bridge thermocouple alongside a regular Pt/Ptl3Rh thermocouple, temperature offsets were quantified as the wirebridge thermocouple short-circuited at the melting points of the pure metals. At the melting points of gold (1064°C) and palladium (1555°C), average measured temperature offsets were -2.1°C ± 2.3°C and 0.2°C ± 0.4°C, respectively. Results from the copper and nickel wire-bridges were inconclusive. The paper concludes with a discussion on the potential industrial applications of the technique.IntroductionThermocouples are probably the simplest of all temperature sensors, but are widely utilized due to simplicity, versatility and ability to handle a variety of experimental conditions and industrial applications. Additionally, thermocouples are often the only option in research laboratories requiring high temperature measurements, and a high level of reliability is usually required from thermodynamic, kinetic as well as safety points of view.The study presented here originated from a test program where the compatibility between different types of carbon-based refractory materials and industrial slag produced in silicomanganese furnaces were investigated on a laboratory scale utilizing the static crucible test[l]. Due to the nature of the silicomanganese production process, the compatibility tests were to be conducted at 1600CC[2]. Details of the experimental set-up utilized for the compatibility tests are discussed in the Experimental Set-up and Method Statement section later in this paper."

Jan 1, 2012

By Shunhong Huang

Thirty-five soils were sampled from three sites at different distances from chromium slag heap of a Iron-alloy factory, namely, nine from site A located under the chromium slag and eighteen from Site B in the vicinity of the factory and eight from site C far from the factory. The contents of total Cr in these soils from site A, B and C were 1666.0±1310.9 mg? kg - 1,1136.2±1844.6 mg? kg - 1 ,300.4 ±165.1 mg? kg ? 1, respectively. The contents of water soluble Cr were 59.3±77.57 mg? kg ? 1,0.6 ±0.3 mg? kg - 1 ,0.5±0.3 mg? kg - 1 , respectively. In order to evaluate soil health, the activities of four soil enzymes (catalase, polyphenol oxidase, dehydrogenase, alkaline phosphatases) were analyzed. The results have shown that dehydrogenase activity was greatly depressed by conditions in the heavy chromium-contaminated sites. Negative correlation was observed between dehydrogenase activity and the distance from the chromium slag heap, however, the activities of catalase, polyphenol oxidase, alkaline phosphatases in soils from the three sampling sites mentioned above did not differ significantly. The result imply that of dehydrogenase activity could be used as an indicator for the chromium pollution level in the area of Iron-Alloy factory and for the stability level of the soil ecosystem.

Jan 1, 2008

Hazardous waste has often very complicated chemical compositions in a variety of physical forms and is normally processed in rotary kiln incinerators. Due to large variations in waste types and difficulties in feed characterization, the complex transport processes within the incinerator are not well understood, and the incineration process meets challenges in a smooth operation, and expects various uncertainties in the process chemistry and emission control. For better understanding of the incineration process, simulation was carried out by using Computational Fluid-dynamics (CFD) to characterize temperature and species distribution in the incinerator. In order to catch certain aspects of thermal and chemical behavior, a novel approach is proposed to represent approximately the waste streams and the subsequent combustion process. Hazardous waste in various forms from an industrial-rotary-kiln waste incinerator is firstly converted to a hydrocarbon-based virtual fuel mixture with approximately the same HIC molar ratio and calorific value. The simulation of the combustion process of the simplified hazardous waste was proceeded with a combustion model. The distribution of temperature and chemical species especially the remaining CO in the system is preliminarily investigated. Distribution of CO concentration, as a good indicator of emission level for the incineration process, could be used to evaluate the emission control. The predicted temperature distribution has been compared with available measurement data from an operating rotary kiln waste incinerator at A VR-Chieme, in the Netherlands. Reasonable agreement has been reached between the measured and predicted temperature data. [n the next step, measurement of species distribution in the system is planned to further validate the combustion model.

Jan 1, 2003

By H. Fukuyama

The wetting behavior of single crystalline MgO by fayalite-type slag melts has been studied by the sessile drop technique incorporated with high temperature X-ray radiography. The experiments were performed under oxygen partial pressures of 10-6 and 10-4 Pa at 1473 K. Mass ratios of iron to silica, Fe/Si~, in the slag employed were 1.4 and 2.0. To investigate the interfacial reaction, experiments using high density MgO crucibles were also conducted. The reactions at the interfaces were examined by Electron Probe Microanalysis. The contact angles between the slag melts and the MgO substrates were found to be relatively low, ranging from 30 to 10 degrees. The surface tension of the slag was 0.4 N/m for a slag of Fe/Si02 = 2.0. Two phases, magnesiowiistite and olivine, were observed at the interface. Interdiffusivity in magnesiowiistite solid solution was determined as a function of iron oxide content. Phase relations between magnesiowilstite and olivine, and the growth rates of both phases, are also discussed

Jan 1, 1996

By Run-boWang, Fan-yi Meng, Jian-Liang Zhang, ZheWang

To elucidate the influence of high Al2O3 content on sinter softening and melting behavior, heating-up reduction test under load was carried out. In addition, microstructure study of sinter bed structure change at a different temperature was also made and the mechanism that the effect of Al2O3 content on sinter softening and melting property was discovered. SEM results showed that the increase of Al2O3 content favored the formation of Al2O3-rich slag phase, such as the eutectic (2CaO·SiO2-2CaO·Al2O3·SiO2-FeO) and gehlenite (2CaO·Al2O3·SiO2), resulting in the decrease of sinter Ts temperature. Further, high Al2O3 content improved the concentration of metallic iron and lowered the dripping temperature due to the decrease of slag liquidus temperature and viscosity. At a fixed basicity, it was indicated that there was a relationship between Al2O3 content and sinter softening-melting property. Based on the results, counter strategies to cope with the adverse effect of high Al2O3 content on the cohesive zone property were also proposed. It could provide guidance for the blast furnace operation of sinter with high Al2O3 content.

Jan 1, 2015

By XUEWEN WANG, Bowen Li, Mingyu Wang

A novel technology characterized by higher extraction of vanadium and recovery of valuable elements was developed to recover vanadium from stone coal. The brief flow of the novel technology mainly includes low temperature sulphation roasting, water leaching, recovering potassium, aluminum, copper and selenium, solvent extraction enrichment vanadium, precipitation of red vanadium, removal sodium from red vanadium and calcinations. The total recovery of vanadium reached 76.3%, which was higher than the current applied technology. The novel technology was environmentally-friendly and could extract vanadium from the stone coal, in which the content of V2O5 was less than 0.8%.

Jan 1, 2015

By T. Wang, R. G. Reddy

"The corrosion of stainless steel SS316L in a low melting point novel LiNO3-NaNO3-KNO3- NaNO2 eutectic molten salt mixture was investigated at 695K. After long-term isothermal dipping corrosion experiments, the SS316L samples were analyzed using scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS) to determine the topography and corrosion products. Dense and protective lithium iron oxide scale formed on the surface and prevented the SS316L sample from further severe corrosion. Therefore, SS316L is considered to be suitable construction material for solar thermal energy storage materials containers.IntroductionMolten salt mixtures have been considered as potential candidates for thermal energy storage and heat transfer media in solar energy applications. To apply the molten salt in the energy transfer process, the standard pipes made of stainless steel must be utilized to carry the molten salt mixtures in parabolic trough system of solar power production. The pipes encounter continuous flow of hot and cold molten salt every day. Thus corrosion of stainless steel in molten salt mixtures becomes extremely essential for the long-term utilization of the thermal energy storage media. The corrosion of passivity materials inside high temperature molten salt systems have been studied which gives fundamental understanding of basic mechanism about the corrosion process [1-8].The corrosion behavior of Fe-Ni-Cr alloys in an equi-molar LiNO3–NaNO3–KNO3 mixture was studied [9]. According to the XRD analyses, the major phases in the oxide scales were identified as LiFeO2, Fe3O4 and Cr2O3. A HITEC® salt mixture (NaNO3–NaNO2–KNO3) was also tested as a corrosion medium for stainless steel [10] and the corrosion rate was found to be affected by the protective oxide layer. In most cases, the alloys having more than 10wt% chromium show high resistance to corrosion in molten salts."

Jan 1, 2014