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By B. J. Beaudry

The preparation of alloys containing one to two percent of the volatile lanthanide metals Sm, Eu, Tm and Yb in the high melting point (HMP) rare earth metals Sc, Y and Lu was accomplished by a vapor deposition, diffusion method without crucible contamination. The method avoids the melting of the HMP metals which would introduce impurities from the crucible, generally Ta or W. Plates of the HMP metals were hung from the lid in the upper part of the Ta crucible. The volatile metals were placed on the bottom and the lid welded in place under an atmosphere of helium. By proper selection of thee alloying temperature, the effusion of the metal vapors, through the helium atmosphere was slow enough to permit diffusion to occur and prevent refluxing of the newly formed alloy. Very volatile metals such as Mg required a Knudsen cell with a suitably sized hole to prevent too rapid transfer of the low melting metal. Electron microprobe analysis of a cross-section of the HMP metals showed a homogeneous distribution of the volatile metals. The time and temperature required to obtain a homogeneous rare earth alloy without contamination are given. The use of a Knudsen cell to form magnesium-rare earth alloys is reviewed.

Jan 1, 1992

By Susumu Nagae, Hajime Ikeda

Recently, a number of mine development projects have been setback by social, economic and, environmental circumstances that had not been seen before. Many of these problems do not always originate from direct mine pollution. Typical examples of these are· conflicts between the exploration company and the local residents, sudden objections just before the development is to begin, and unexpected tightening of environmental regulations. The common background to these problems is expanding global environmental awareness. This includes complex factors ·such as the expansion of exploration to remote regions, the brisk activities of environmental NGOs, the increase of international environmental laws and, governmental policy changes. Today, the range of issues concerning mine development is widening significantly. The participation of local residents arid NGOs in the development planning, together with the company and government, has become essential for smoothly carrying out mine projects and making them more beneficial for stakeholders. Introduction The common image of the environmental problem with respect to mining is direct mine pollution, such as the collapse of tailings dams, pollution from refineries, and acid mine drainage. All over the world, the mining industry has made large investments in capital and technology to solve and prevent mine pollution, and these efforts have been making steady achievements. However in recent years, new cypes of environmental problems which are not originating directly from mine pollution are emerging frequently. Most of the problems are concentrated at the exploration stage to early stage of development, which have less impact on the environment. In the worst case, mining project may be forced to cancel and could cause serious damage to the industry because they could not collect their investment. I would like to take a general view of the examples of new types of trouble, their characters, background, and strategies against these problems.

Jan 1, 2000

By Lei Wang, Xiancong Zhao, Hongxu Li, Lifeng Zhang

Recovery of Fe from red mud has been studied using statistically designed experiments. The effects of three factors, namely: reduction temperature, reduction time and proportion of additive on recovery of Fe have been investigated. Experiments have been carried out using orthogonal central composite design and factorial design methods. A model has been obtained through variance analysis at 92.5% confidence level.

Jan 1, 2015

By Zhong g. Shui-ping

A new type Pb-Ag (0.8wt%)-Bi (0~5.0wt %) alloy used as anode in electrowinning of zinc from sulphuric acid electrolytes was prepared. The electrochemical properties of this ternary lead alloys have been tested and compared with those of Pb-Ag (0.8wt %) anodes used in industry. Results show the anodic overpotential decreases with the increasing of Bi content in the alloys. When the content of Bi was 1.0 wt% and 5.0 wt%, the anodic overpotential is about 40?50 mV and 60?80 mV lower than that of Pb-Ag (0.8wt %) alloy, respectively. The formation of oxide layers on the surface of these alloys was traced by LSV methods and the composition of the anodic oxide layers was characterized by XRD and SEM analysis. The surface layer on the two type anodes examined is mainly composed of a?PbO2 and ß?PbO2. But different structure of the surface layer was observed, Pb-Ag (0.8wt%)-Bi (1.0wt %) has a more fine-grained structure as compared to Pb-Ag (0.8wt %). But the film on Pb-Ag (0.8wt%)-Bi (3.0wt %) alloy is rather friable, cracked and not tightly attached to the anode.

Jan 1, 2008

By S. Raghavan

The thermodynamic activities of MgO in the solid solutions that can exist in the system NiO-Mg0-Zn0 are determined by measuring the EMF of the cell: O2 (g), Pt / MgO, MgF2 // MgF2 // x MgO + yNiO + (1-x-y)ZnO / Pt, O2 (g) / MgF2 in the temperature range 1190-1237 K. Equilibrium phases were prepared along the quasi- binary lines MgO/NiO = 0.1765,0.3333, 1.0,3.0 and 5.667 with the ZnO contents being 0.1, 0.2, 0.25, 0.35, 0.5, 0.75 and 0.9. The crystal structures of the phases were identified by X-ray diffraction. Results obtained so far show that a single phase MgO-rich cubic solid solution exists upto 0.2 ZnO content and for compositions above 0.25 ZnO, a second ZnO rich wurtzite phase forms in addition. Activity measurements show that for low MgO and ZnO contents, the MgO activities exhibit ideal to slight positive deviation from ideality and at higher MgO contents, a negative deviation is shown. Further studies are in progress.

Jan 1, 1993

By H. Y. Cheng

A pulse column solvent extraction system was evaluated as an alternative to mixer-settlers for the separation and purification of rare earths. The column tested had an inside diameter of 44.5 mm and had 36 sieve plates with a free area of 25%. Pulsing was provided pneumatically using a solenoid valve controlled by a timer so that both pulse amplitude and frequency could be varied. Feed to the column was a mixed rare earth chloride solution containing 10 g RE L-1. The extractant was 5% Ionquest® 801 in Shellsol 2037 diluent. Hydraulic performance of the pulse column was excellent with no propensity towards stable emulsions or crud formation under normal operating conditions. The column was operated in organic-continuous mode with flow rates chosen so that yttrium and the heavy rare earths were extracted with high efficiency while the light rare earths were rejected. Yttrium extraction varied from 83 to 99.2%. Concentration profiles were measured in both the aqueous and organic phases, and, from this data, the height of a transfer unit (HTU), the mass transfer coefficient (Kxa) and the continuous-phase axial dispersion coefficient (Ey) were computed. The HTU ranged from 17-92 an which is within the range of values reported for other (non rare earth) pulse column systems.

Jan 1, 1992

By R. Upadhyaya

Aluminium alloy matrix cast composites have been synthesised by incorporating fine graphite powders (0.5 - 20 µm size) and chopped carbon fibres (6.5 pm P). 3-6 mm length) by liquid metallurgy technique. Incorporation of these second phase materials exceeding 6-8 wt% invariably resulted in agglomeration of the dispersoids and sometimes leading to even total rejection. It was found that small additions of mischmetal (1-3 wt%) during dispersion resulted in better incorporation without much agglomeration of the dispersoid as evident from the macro and micro structures of the composites. Further, the additions of mischmetal increased the volume of the effective incorporation of the dispersoid even to the extent 50- 60%. The mischmetal addition results in a significant increase in the power factor of the stirrer motor indicating an apparent increase in the viscosity of the system. The higher viscosity of the melt increase the shear transmission conditions within the melt during stirring thereby breaking the agglomerates of the dispersoids. The increased viscosity of the melt seems to be due to the formation rare earth - aluminium inter metallics precipitation, as observed in the metallographic studies, thereby making the process a "pseudorheocasting? technique. A provisional patent has been filed based on this work.

Jan 1, 1989

By J. A. Innes

"""The oxygen, next uniting with the carbon, sent up an ever-increasing stream of sparks and a voluminous white flame. Then followed a succession of mild explosions, throwing molten slags and splashes of metal high up into the air, the apparatus becoming a veritable volcano in a state of active eruption.""IntroductionHenry Bessemer F.R.S(An autobiography, 1905)Thank you Mr Chairman for the opportunity to speak: at this, the opening session of your International Symposium on the subject of ""Injection in Pyrometallurgy"". Judging from the list of papers to be presented over the next three days, the Symposium promises to provide a most valuable addition to our existing knowledge base in what is now an extremely active area of R&D investigations. Whilst we have obviously come a long way since Sir Henry Bessemer's pioneering experiments of the mid-19th century, there is still much for us to learn.Most importantly, the Symposium offers a further opportunity to acknowledge the many significant technical contributions made in this field by the Organising Committee's special guest, Professor Howard Worner - one of this country's most respected research leaders.When first approached to give this talk I had two areas of concern. Firstly, I was not entirely clear just what injection metallurgy was meant to cover. How should the overall scope of this particular subject be defined?My second concern related to Howard Worner himself - a man for whom I have the highest personal regard and who, in fact, played a most influential role in respect of shaping my own career. Having already spoken about Howard's achievements on earlier occasions, I wondered what I could sensibly add.Notwithstanding these personal reservations, I am delighted to be here with you this morning. If my thoughts on the meaning and scope of injection metallurgy appear to be slightly off-course, and if Howard should perhaps recognise some repetition in my remarks, then I hope I can be forgiven."

Jan 1, 1996

By B. M. Fisher

A process for making electrolytic copper of high quality from copper flotation concentrates is described. The concentrates are first slurried and then subjected to a high-temperature, high-pressure, oxidation-leaching operation under controlled conditions. The resulting slurry from the oxidation-leaching operation is cooled or flashed to atmospheric pressure and then subjected to a solids-liquid separation. The separated liquor, containing the recovered copper values, is cooled and then fed to an electrolytic deposition operation where metallic copper cathodes of high purity are produced. The spent electrolyte is then subjected to a sulfide treatment to precipitate the residual amounts of copper not deposited in the electrolytic cells. The precipitated copper sulfide is recovered and recycled in the form of a slurry to the initial stages of the process.

Jan 1, 1976

By Gökhan Demirci, Ishak Karakaya

"Energy consumption in electrolytic magnesium cells is well above the theoretical values. However, the mechanism of the back reaction, the main cause of the current losses, has not been fully understood yet. Magnesium dissolution into the melt is generally regarded as the limiting step for the back reaction. Accordingly, present cell designs are made with priority given to fast magnesium removal from the cell. However, experimental data and modeling results in this study indicate that the limiting step for the back reaction between magnesium and chlorine is the chlorine dissolution into the electrolyte when physical contact between electrolysis products was eliminated. Effects of chlorine bubbles on the current efficiency and the cell potential were investigated. Results show that the extent of back reaction is proportional to the chlorine surface area in contact with the electrolyte per unit time, and the cell potential increases with the amount of chlorine bubbles inside the electrolyte.1. IntroductionMagnesium is less dense than the electrolyte in electrolytic magnesium production. Therefore, both electrode products, magnesium and the chlorine gas, move upwards inside the molten salt electrolyte during electrolysis. The upward motion of electrode products promotes the most important current loss mechanism, the ""back reaction"". Separation of the highly reactive species; liquid magnesium and the chlorine gas in the cell, to prevent their recombination is one of the main concerns in cell designs. The employment of large inter-electrode distance or a separation wall in early cell designs; decreased the extent of recombination, but increased the cell voltage and energy consumption. Recent cell designs, on the other hand, make use of lifting action of chlorine gas [1,2] by utilizing smaller inter electrode distances to separate the magnesium and chlorine gas faster. Although energy consumption was reduced, but more physical interactions between electrode products make electrolytic magnesium cells still highly inefficient when energy consumptions are compared with the theoretical values. Today, the most efficient industrial cells utilizing high purity feed operate at 10.5-11.5 kWh kg-1 Mg [3-5] and it is considerably higher than the theoretically attainable value of about 6.0 kWh kg-1 [6]. This large gap demonstrates the necessity of more research on physics and chemistry of magnesium cell electrolysis."

Jan 1, 2011

By Afrodite Ntziouni, Vassilia Kasselouri – Rigopoulou, Athanasia Kyritsi, Konstantinos N. Pistiolas, Stamatia Gavela, Konstantinos Kordatos, Lazaros Iliadis

"The present study deals with the production and characterization of rice husk ash (RHA) and its use in the synthesis of zeolite of type ZSM-5. Rice husk was combusted in various temperatures with aim to find the suitable conditions for the production of amorphous silica. The resulted amorphous silica ash was then utilized as a starting material for the synthesis of ZSM-5 zeolite using the low temperature and atmospheric pressure process. The method led successfully to the synthesis of highly siliceous zeolite of type ZSM-5. The produced material was characterized using x-ray diffraction (XRD) and scanning electron microscopy (SEM).IntroductionRice husk is a major by-product of the rice-milling industries and it is usually used as a fuel for steam generation due to its high calorific power. During its combustion, rice husk ash (RHA) is produced. Knowing that the annual rice world production is over 615 million tons (2005), thus resulting in a potential production of more than 22 million tons of RHA [1], it can be understood that the RHA disposal is a crucial issue towards the environmental protection. However, due to the high silica content, RHA can be used as an alternative cheap source of silica for many uses, including as filler in polymers [2], concrete [3] and synthesis of zeolites [4-7].The burning of rice husk in air results in the formation of RHA with content in SiO2 that varies from 87 to 97% depending on the burning conditions, the rice variety, the climate and the geographic area [8]. Some small amounts of inorganic impurities are always present in the ash along with unburned carbon. The unburned carbon can be removed from the ash by further heating treatments in high temperatures, but this usually leads to the crystallization of the amorphous silica to cristobalite and/or tridymite [9]. The crystallization of the contained silica of the ash is also occurred when the burning conditions of husk are uncontrolled [10]. This crystallization is a disadvantage towards the preparation of silicon based materials, because the silica ash is rendered inactive in its crystalline form [11]."

Jan 1, 2008

By Vladimir Lobanov, Pritchinm Alexander, Nikifor Ageev

"Sulfuric anhydride is one of the most voluminous technological emissions. The possibility of high-temperature SO2 oxidations without catalyst in presence of calcium-bearing filling materials (CaO, Ca(OH)2 and CaCO3) with obtaining of binding material on the basis of waterless calcium sulfate is studied. Due to application package HSC-4 the thermodynamic analysis of the specified interactions is made and following conclusions are drawn: 1) Reactions are feasible in the all range of investigated temperatures (400 – 1000 °?); 2) The best results should be expected at use of ???; 3) The heat of reaction does possible autogenous behavior of process. The researches have shown: 1) Practical possibility of the process; 2) SO2 oxidation without the catalyst is feasible in presence of ???, Ca(OH)2 and CaCO3; 3) The optimum temperature range is 600-800 °?; 4) The content of waterless calcium sulfate in a product reaches 48% that makes it possible to use as the binding material; 5) At excess of ??? the degree of SO2 collection is nearer to 100%. Introduction At processing of sulfide raw materials in metallurgical furnaces the significant amount of sulfur, mainly in the form of sulfuric anhydride is escaped. Rich gases (SO2>3 %) are used for the sulfuric acid or element sulfur production. Chemism of sulfuric acid manufacturing is based on catalytic high-temperature oxidation of anhydride. Poor gases of metal works (SO2 =2,5 %) and power combustion units (SO2 =0,5 %) after clearing discharge into the atmosphere. Commonly, to recovery of weak sulfuric anhydride the chemical and physicochemical methods are applied. A few chemical ways of recycling sulfur dioxide are applied practically. In a number of methods for SO2 recovery a pulp of metals oxides (magnesium, zinc, etc.) with formation of sulfites is used. In other case sulfuric anhydride is catch by weak sulfuric acid in the presence of an oxidizer (pyrolusite ore). Methods of absorption SO2 by solid sorbents, (carbon fibers, silica gels, zeolites) are known and put into practice. Regeneration of the saturated sorbents is realized by thermal decomposition or extraction. Obtained as a result high-concentrated solutions are a commercial product."

Jan 1, 2008

By Jean Igor Margem, Lucas Barbosa de Souza Martins, Frederico Muylaert Margem, Noan Tonini SImonassi, Sérgio Neves Monteiro, Rômulo Leite Loiola

"Fibers of giant bamboo (Dendrocalmus Giganteus) are amongst the strongest lignocellulosic fibers. Although studies have been already performed, limited information exists on the mechanical properties of polymeric composites reinforced with continuous and aligned giant bamboo fibers. This work evaluates the tensile strength of this type of composite. Standard tensile specimens were fabricated with up to 30% of fibers aligned along the specimen's length. The fibers were press molded with a commercial epoxy resin mixed with a hardener and cured for 24 hours at room temperature. The specimens were tested in an Instron machine and the fracture surface analyzed by scanning electron microscopy. The tensile strength increased significantly with the amount of giant bamboo fiber reinforcing the composite. This performance can be associated with the difficult of rupture imposed by the fibers as well as with the type of cracks resulting from the bamboo fiber/epoxy matrix interaction, which prevents rupture to occur.IntroductionDue to growing concern about the ambient impacts from industrial activities, our society is ever more using environmentally friendly materials. In this regard, cellulose-based natural fibers, known as lignocellulosic fibers, become a promising solution. Nowadays, they are being considered as a substitute for synthetic fibers, such as glass fiber, used by the industry on a large scale [1-5]. The application of these natural fibers is also motivated by many advantages like good toughness and less wear of equipment used in the processing of composites. In addition, such composites are environmentally friendly because they are renewable, biodegradable and neutral with respect to C02 emissions, the main responsible for global warming and climate changes. [3,5,6].Lignocellulosic fibers also have some disadvantages in relation to synthetic fibers such as the difficulty of coupling with polymer matrices, due to the hydrophilic character of fiber and the hydrophobic nature of the matrix, as well as dimensional heterogeneity [ 4,5]. This last one is characteristic of the nature of this material and constitutes an obstacle to the use of these fibers in certain projects, especially those that aim high performance. The above mentioned disadvantages are worrisome reasons for the occurrence of reduction in the strengthening capacity, as indicated by the rule of mixtures for composites [7]."

Jan 1, 2013

By Liang Yu, Yuhua Li, Yuanchi Dong

"High alumina slag, with alumina normally more than 15 pct, is encountered with blast furnaces in China because of high alumina/silica ratio in iron ore as well as sinter and high ash content in coke for cost reason. High alumina slag with high viscosity and high liquidus temperature would lead to higher slag volume and thereby, furnace productivity. In the present work, liquidus temperature of high alumina slag, based on Meishan factory, Baosteel China, were investigated. A liquidus temperature model was introduced in the present work based on basic physical chemistry theory and focused on the chemical composition area used in Meishan factory(pct): Al2O3 from 14 to 17.5 and MgO from 8 to 12, so that the blast furnace slag could be designed for optimum blast furnace performance.IntroductionBlast furnace slag composition[1] has very important bearing on its physicochemical characteristics which affects smoothness of operation, slag handling, coke consumption, the degree of desulphurization, hot metal productivity and its quality etc. The slag properties which affect most are liquidus temperature, viscosity, sulphide capacity and alkali capacity. Variation of these slag characteristics with composition and temperature has been a field of active researches as these its great influence on the blast furnace operation. In the early years, most of these studies were carried out over low alumina blast furnace slags with alumina normally less than 15 pct. High alumina slag was first introduced in India because of its high alumina/silica ratio iron ore as well as sinter and high ash content in coke[2]. And then this problem becomes common as higher alumina/silica ratio iron ore imported and used [2-5]. The most important problem caused by high alumina content is liquidus temperature and then viscosity of the slag.Generally speaking those reported works [2-5] investigated a pretty wide range of chemical compositions and then obtained complex model, respectively. In fact, every factory has its own interest because of different resources. For example, the Al2O3 content from 20% to 30% pct was studied in Tata Steel India [2], but it is too high for Baosteel Meishan. A very lower percentage of alumina content, 14-18 % pct, was mainly used."

Jan 1, 2008

By J. -C. Tedenac, C. Colinet, X. Tao, P. Jund, R. Viennois

"We report an ab-initio study of the stability and electronic properties of transition metal silicides in order to study their potential for high temperature thermoelectric applications. We focus on the family M5Si3 (M = Ta, W) which is stable up to about 2000 °C. We first investigate the structural stability of the two compounds and then determine the thermopower of the equilibrium structure using the electronic density of states and Mott’s law. We find that W5Si3 has a relatively large thermopower but probably not sufficient enough for thermoelectric applications.IntroductionIn the search of new sustainable energies, thermogeneration of electricity is one of the promising ways, notably because it is able to produce electricity from different kinds of heat wastes and to its portability. However, despite recent progress in the field, the state-of-the art materials have specificities making their mass-production difficult or even impossible: toxicity (thallium, chalcogen or/and pnictogen based alloys), weak abundance (tellurium based alloys) or cost (germanium or rare-earth based alloys). For all these reasons, finding thermoelectric materials without these drawbacks is vital if we wish to use high temperature thermoelectricity for generating electricity in the near future. Due to their abundance, low cost and low toxicity, transition metal silicides are candidate materials of primary interest and the slightest advance in this field would immediately find an application for the thermogeneration of electricity."

Jan 1, 2011

By Jin-yan TIE, Ke-xin JIAO, Qian Li, Hai-bin ZUO, Jian-Liang Zhang, Meng SHEN

This paper designs three factors such as temperature, pH, conductivity and three levels of orthogonal test. Temperature is a significant factor. However PH and conductivity are not significant through poor analysis. Further research is conducted on the temperature. Temperature stability is 50 . Suitable water velocity is 2.3m/s, which is calculated based on the largest part of the heat flux intensity and the corresponding water temperature should be controlled with 1.5. Meanwhile, water velocity increased has little effect on the heat transfer capabilities.

Jan 1, 2015

By Kenji Morinaga, Hiromichi Takebe

"Ge-S binary glasses in the range 57 to 90 at %S at 0.5 to 3 at %S intervals were prepared by a conventional melting technique using fused quartz ampoules as melting containers. Impurities contaminated during preparation process are evaluated by IR spectroscopy. The causes of impurity contaminations are discussed. Density data in a systematic series of Ge-S glasses is demonstrated. IntroductionSulfide glasses are of particular interest for new laser and nonlinear optical materials in the near-infrared and infrared regions [1]. Sulfide glasses have the features of low-phonon-energy and high refractive index with moderate rare-earth ion solubility. The low-phonon-energy is favorable for the reduction of nonradiative rate for the emission of rare-earth ions. The high refractive index results in a high radiative-rate and in a high third-order nonlinearity. However, impurities may degrade the superior optical properties of sulfide glasses.In this work Ge-S glasses were prepared by a conventional melting technique. Impurities contaminated during the preparation process are evaluated and their causes are discussed for future improvements. The measured densities of Ge-S glass samples were compared with the results of previous studies [2], [3]. Ge-S glasses have some favorable properties for practical .applications including non-toxicity, good thermal and chemical stabilities."

Jan 1, 2000

By Peter Olubambi, Babatunde Obadele, Oluwagbenga Johnson

"The microstructure and corrosion behaviour of titanium carbide (TiC) reinforced duplex stainless steel matrix surface composites synthesized by laser melt injection technique was investigated. The surface melting operation was conducted using a 4.4 kW CW Nd:YAG laser with laser power of 1.5 kW, scanning speed of 0.4 to 1.0 m/min, beam size of 3 mm and argon shield gas flow rate of 4 L/min. The morphologies and microstructures of the coatings examined using field emission gun scanning electron microscope (FEGSEM) revealed homogeneous distribution of fine precipitates of TiC in the matrix, while X-ray diffraction (XRD) analysis confirm no phase change. TiC addition to the steels significantly increased hardness value to about 547 Hv0.1 but slightly decreased the corrosion resistance of the steels in 3.5% NaCl possibly due to the intergranular carbide coating that prevented chromium from forming continuous passive oxide layers.IntroductionComposite materials evolve from the idea of combining two basically dissimilar materials with different physical and mechanical properties to arrive at a product whose final properties are superior to those of the individual components [1]. Metal matrix composites (MMCs) are receiving much attention and are the focus of intense research and development worldwide for aerospace, automotive and other applications because of their excellent combination of ductility and toughness of the metallic matrix with high hardness and strength of carbides reinforced in the matrix [2]. Surface modification techniques such as laser, thermal spray, plasma spray, chemical vapour deposition have been use to fabricate MMCs. Laser melt injection (LMI) is a surface modification technique known since the 1980s [3] has been used to improve surface properties of metallic alloys such as aluminium, titanium and steels [4-6]. It involves the lateral injection of carbides, ceramics and cermets blown by a gas stream into a liquid metallic pool, created by laser irradiation of the top surface of the base material."

Jan 1, 2012

By Chikabumi Yamauchi, Masami Tashiro, Toshiharu Fujisawa, Hiroyuki Snano

"Rare earth metals usually contain large amount of oxygen because of their reactiveness, and therefore oxygen removal is one of the major problems on the purification of rare earth metals. In the present research work, halide flux treatment at high temperature under inert gas atmosphere was applied to the oxygen removal from neodymium. NdF3 was used as a halide flux. Deoxidation reaction and its mechanism were discussed based on the experimental results. Halide flux treatment is very effective for oxygen removal from rare earth metals.IntroductionSolid Sate Electrotransport (SSE) process has been successfully applied for the elimination of interstitial gaseous impurities from chemically active metals[l]-[5]. However, to achieve a higher effectiveness of the SSE process, it is required a very low initial impurity content in the metal. In case of rare earth metals, it is known that they usually contain large amount of oxygen that should be lowered as much as possible before applying the SSE process. In addition, if effective oxygen removal is achieved by simple process, it is significant also from the industrial viewpoint. In the present work, the application of a halide flux treatment is investigated to remove oxygen from neodymium by using NdF3 as a flux. At first, deoxidation reaction and its mechanism were discussed based on the phase diagram of the Nd-NdF3-Ndp3 quasi-ternary system. Based on the results, oxygen content in deoxidized neodymium was calculated theoretically and it was verified by deoxidation experiments."

Jan 1, 1998

By Tuneo Funahashi

Sumitomo Shisaka Works has been treating EAF(Electric Arc Furnace) dust to recover zinc and lead in the Waelz Kiln process. Since its commencement of operation in 1977, many technical improvements have been successfully made to increase the production capacity and the zinc recovery rate. The EAF dust charge to the Waelz Kiln was increased from 35,000tly to 120,00OtIy, and the production of zinc oxide now amounts to 40,000tly. The zinc content in the clinker was decreased from 5% to less than I%, by the optimization of the kiln heat pattern with no accretion trouble. And the clinker has become more a valuable raw material for steel making. This paper describes the above progress ofthe SMM Waelz Kiln process operation at the Shisaka Works.

Jan 1, 1998