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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 Y. Maeda

Non-ferrous smelting furnaces generally install a gas cooling system for treatment of waste gas containing SO2,. From the point of view of corrosion resistance and recovery of waste heat, the high pressure boiler system is the best way to cool gas, however this system requires high initial investment and relatively higher operating costs. Because the feasibility of this boiler system greatly depends on the smelting process and scale, other lower temperature systems, e.g. water-cooled jacket system, are more suitable if the smelting process does not produce enough steam nor generate enough electricity to compensate operating cost. In additton, the water-cooled jacket system is simple in structure and easy to operate. For those reasons, it is applied widely. A new smelting furnace was planned in our factory and it was necessary to install waste gas cooling equipment. In our case, a water-cooled jacket system was more feasible because of the low gas volume and high dust content. It was also expected to operate without maintenance for ten years. On the other hand, some leakage problems with the water-cooled jacket had been experienced in the past. That is because SO2 In the waste gas changed into sulfuric acid which corroded the jacket material. As the first step, several data from actual' usage were reviewed to throw light on the corrosion process, and an appropriate procedure to determine the operating temperature of cooling water was obtained. For the basis of this study, a water-cooled jacket system was newly designed and tested for three months in a pilot plant. After this system's performance was confirmed, it was installed in a new furnace as a commercial plant. After one year of operation, the initial thickness of carbon steel jacket remains almost the same.

Jan 1, 1992

By T. R. A. Davey

It is often important in the study of a process to determine whether the limitations are governed by equilibrium or kinetic considerations. Sometimes it is possible to devise a design of the process or the equipment so that the apparent. limitations set by equilibrium considerations are overcome. In this paper, detailed consideration is given to the lead refining processes of sulfiir-decoppering and of vacuum dezincing to illustrate this, and possible implications for other refining processes are indicated.

Jan 1, 2000

By Theo Lehner

Nasty, according to the Collins Dictionary, comprises the adjectives: bad, critical, dangerous, dirty, odious, serious, severe, sickening, unpleasant etc. From this we may at first conclude that each individual smelter relying on its own specific business surrounding would have a special definition of its nasties. But common product standards and common metallurgy makes us experience common nasties. To get an idea of possible problem elements we start with the demands on the products: [ ]

Jan 1, 1994

By Aichun Zhao, Rui Wang, Yihong Li, Yanping Bao, Yafeng Ji, Jiansheng Liu, Xiao Hu, Qingxue Huang

The slag entrapment under different conditions of 80t blowing argon ladle furnace was investigated by physical simulation. The water was used to simulate liquid steel and liquid paraffin was for slag. The processing of slag entrapment under different blowing structures was analyzed and the critical velocity and critical droplets diameter of describing it was obtained. Based on the experiments, the relationship between the interface flow velocity and the critical blowing rate CBR was deduced. In the real process, it is suggested that the bottom blowing rate is from 40 L/min to 180L/min when the interface tension is 0.12~1.2 N/m during the soft argon blowing.

Jan 1, 2016

By Z. S. Wronski

In rapidly solidified Fe-Nd-B permanent magnet alloys, the content and distribution of Nd-rich intermetallic and Fe-phases determine coercivity Hc and remanence Br. Consequently, microstructure plays a crucial role in deter- mining the (BH) max-product of permanent magnets fabricated from these alloys. A study has been initiated to investigate changes in microstructure and the effects on magnetic properties as the material is processed from arc-melted ingot to melt-spun flakes and finally to a product consolidated by hot-forming. Anisotropic magnetization behaviour has been observed in rapidly solidified flakes after low-temperature annealing.

Jan 1, 1989

By H. Aminian

Copper electrowinning (EW) is an important process in connection with the solvent extraction to produce pure and marketable copper cathodes. A phenomenological model was developed to simulate the copper electrowinning process. The simulator is used to predict the operation of the Mines Gaspe pilot plant electrowinning cells put in operation in 1996. Results confirm the potential of the simulator that would subsequently be used for student training, process optimization and assessing the performances of control strategies.

Jan 1, 1999

By R. M. Donovan

This paper documents the efforts to improve quality and production at the Amarillo Copper Refinery. It summarizes the change in attitudes, work procedures, equipment maintenance, instrumentation, and the ever changing market. The Amarillo Copper Refinery is dedicated to the ASARCO Management System, ISO-9002 and continuous improvement.

Jan 1, 1999

By L. N. Ertzeva

The process for thermal treatment of current pyrrhotite concentrate in reducing environment with the use of disperse metal iron as an iron-bearing additive (optimal volume 20-30%), with downstream magnetic separation of the calcine, has been studied. The reduction process has been performed in conditions emulating those of both tube and fluidize-bed furnaces.

Jan 1, 2006

The Port Kembla Copper (PKC) copper smelting facilities were commissioned during 2000. Numerous difficulties were encountered during the commissioning such as multiple reactor tuyere line failures, absorbing acid tower refractory collapse, and Noranda Reactor and Mitsubishi Converter process control problems. These problems are described along with the actions taken to overcome them. Process development is described particularly for the Mitsubishi Converter and Acid Plant.

Jan 1, 2002

By David J. Roha

"The harsh environment of the Carbothermic Aluminum process makes necessary numerical modeling as a means of process visualization and understanding. A brief survey of the various numerical models, with emphasis on CFD, applied in the development of the process is presented.IntroductionThe environment of the Alcoa Carbothermic reactor is necessarily a harsh one, with temperatures approaching 2100 °C and plenty of reactive dust and vapors. As such, it is difficult to directly observe what is actually taking place. Thermocouples can last for a few minutes but are eventually destroyed. The openings to optical pyrometers become occluded with dust and condensation. Graphite sheathing embrittles, reacts away or becomes clogged with condensate. Dip-samples on steel rods are routinely taken, but their interpretation is often unclear.Those measurements that can be reliably taken are invaluable, but often do not provide a complete picture. Therefore from the very inception of the project both physical and computer based models have played an important role. Modeling provides an intuitive understanding of the processes that might be taking place and in very many cases approach quantitative prediction. I will briefly touch upon computer-based modeling performed at Alcoa over 12 years of the Carbothermic project, with special emphasis on CFD. The explanation of physical models is perhaps best left for those with the greatest familiarity with them"

Jan 1, 2012

By Guray Kaya

Boron minerals are widely employed in various fields such as ceramic, glass, cement, metallurgy, etc. Although boron deposits of the world are limited, the production level of boron-based products is continuously increased. Turkiye possesses approximately 73 % of total world boron resources. Etibor Kirka Borax Company of Turkiye produces tincal concentrates and borax pentahydrates. During such productions considerable amounts of concentration and derivation wastes appear. Having considered the increased rate of production it is quite obvious that the level of relevant wastes will also be raised. With this study it was aimed to utilize these wastes in roof tile and brick bodies and to convert them into a form environmentally and human friendly. Newly produced products were undergone to several standard tests for the determination of their shrinkage, water absorption, strength values and coloring parameters. Additionally, micro structural studies were conducted.

Jan 1, 2006

By Sheng-hai Yang

The electrochemical synthesis was conducted in anhydrous ethanol solvent mixed with conductive reagent when tantalum plate was used as anode and stainless steel plate as cathode. The effects of different conductive reagents (such as NH4Br, (CH3)4NCl, (C4H9)4NCl), conductive reagent concentration and the space on the cell voltage and the current density were investigated. The current efficiency of electrosynthesis was more than 95%. The electrolyte, a mixed solution was then undergone air distillation and vacuum distillation to get the final product which was characterized by Fourier Transform Infrared(FTIR) spectroscopy, Raman spectra, 1H-Neclear Magnetic Resonance(1H-NMR) spectroscopy. Carbon and hydrogen contents in the product were determined by elemental analysis instrument. Results consistently show that the product was tantalum penta-ethoxide.

Jan 1, 2006

By Guo Jun

In this study, BaTiO3 ultrafine particles surface-modified with stearic acid were synthesized by the hydrothermal method in a system of BaCl2-TiCl4-NaOH. The effects of NaOH/TiCl4 molar ratio, Ba/Ti ratio and time on structure and morphology of BaTiO3 ultrafine particles were investigated experimentally. The formation mechanism of different crystalline BaTiO3 particles was discussed, and it is considered that in a hydrothermal system, the main factors determining BaTiO3 crystalline are H+ replacement of Ba2+ causing H+ deficiency and anatase growth units involving in crystal growth, which clogs the axial channel for Ba2+ transference. By means of increasing the alkalinity of system and barium content, H+ deficiency and involvement of anatase growth units in crystal growth could be effectively controlled. The results show that when molar ratio of NaOH to TiCl4 is 9 and ratio of Ba to Ti 1.5, and time 8 hours, high purity tetragonal BaTiO3 ultrafine particles with a narrow grain-size distribution and nonpolar surface are obtained at 240oC. The particles have excellent flowability, which is ascribed that the surface polarity of barium titanium powder modified with stearic acid is changed and the interaction between the particles is weakened.

Jan 1, 2006

By L. -C. Lai

A series of LaNi5-based alloys, with partial substitution of Ni by Al, Co, or V, were prepared The gas-phase hydrogen absorption kinetics and pressure-composition-temperature curves were measured The activation became easier and the plateau pressure was reduced as Ni was partially substituted by Al Substitution with Co reduced the hysteresis as well as the hydrogenation capacity, but enhanced the absorption kinetics Vanadium is often considered as a hydride former, but when it was added to LaNi5, it was found that V occupied the B site. A small amount of substitution of Ni with V led to a higher hydrogenation capacity and faster activation rate Based on these properties, an alloys LaNia 25CO0.5V0.1Al0. 15 was fabricated as an electrode. Compared with LaNi4.85Al0.15, it was found to exhibit faster activation, higher discharge capacity, and longer cycle life. The variation of the hydrogenation characteristics is discussed based on the physical and chemical properties of the alloying elements.

Jan 1, 1997

By Lin Yang, Yuanbo Zhang, Zhuoxuan Li, Guanghui Li, Jinghua Zeng, Tao Jiang

A technique has been proposed for recovering iron from hematite-rich diasporic-type bauxite ore in this study. Direct reduction roasting followed by low intensity wet magnetic separation process was carried out. The parameters including reduction temperature and time, sodium salts, grinding conditions and magnetic field intensity for separation of iron were determined. The optimum process parameters as follows: roasting temperature of 1050 oC, time of 60 min, sodium salts involving sodium sulfate, borax, sodium carbonate with dosages of 10 wt%, 2 wt%, 35 wt% respectively, and magnetic field intensity of 1000 Gs with fineness of pulp reached 92.75% passing -0.074mm. Under the optimal conditions, an iron concentrate containing 88.17% total iron grade and iron recovery of 92.51% was obtained, 4.55% total iron grade in tailings. This novel technique provide a potential route for utilizing hematiterich diasporic bauxite ore, recovering iron resource firstly, and extracting alumina from magnetic separation tailings further.

Jan 1, 2015

By V. Jiricny

The novel spouted-bed electrode (SBE) is a cathode system where copper is deposited at a high current density in a moving bed of copper particles. Preliminary results on the deposition of copper from acidic sulfate electrolytes using this novel cathode system were described during Copper '95 conference. Despite a high current density, the electrical energy consumption was equal to or lower than that in the conventional electrowinning. The present paper describes more investigations on SBE. The SBE consists of copper particles with approximately 1 mm diameter onto which copper is deposited from acidic sulfate electrolyte whose composition is similar to conventional electrowinning. Three types of anodes were used in conjunction with the spouted-bed cathode, namely, DSA anode for oxygen evolution, and two novel anodes. One anode is less expensive than DSA; however it showed much promise in energy consumption. At a superficial current density of 2200 A/m2, the energy consumption was around 1.0 kWh/kg copper. The research activities described in this paper were supported by BHP Copper.

Jan 1, 1999

By P. K. Narasimhargahavan

This paper discusses briefly the major reasons associated with the growth and its impact on the energy requirement and Environmental imbalance. A projection based on the present global Alumina and Al requirement indicate a substantial further growth of at least 30% over the next 10 years. It is indicated that the main factors which are likely to influence investments are the environmental factors such as the Climate Change and global response to the growing energy prices and sustainable development. Each of the developed / developing nations must find response to the GHG emissions which will encourage the Al Industry to make an effective contribution to global warming while preserving the international competitiveness of the industry - a challenging task. The efforts shall concentrate on improving energy efficiency in the industry possibly of the order of 25% over the next 10 to 20 years. The developments in this line are discussed.

Jan 1, 2010

By J. M. D. Wilson

An analytical program using a combination of SEM-based image analysis techniques is developed for automated modal analysis of ores containing silicate and other gangue minerals. Previous knowledge, gathered by means of either optical microscopy, X-ray diffraction, SEM, or electron microprobe analysis is used to establish discrimination criteria in the image analysis program. The program initially discriminates minerals on the basis of their relative grey values in a backscattered electron image. For those minerals which have overlapping grey levels the minerals are identified by the program using energy dispersive X-ray spectrometry with X-ray counting for twelve or more elements. This technique is useful to quantify ores in which the gangue minerals are numerous. Two cases of application are presented.

Jan 1, 1999

By Z. Zhang, Cuihuan Huang, Zongshu Zou, Nan Wang, Xueqian Xin

"Vitrification is considered as an attractive procedure for municipal solid waste incineration ash, which can realize the volume reduction and innocent treatment of incineration ash, as well as reuse of bottom ash. The main oxide components of molten ash slag are CaO, Al2O3, SiO2, Fe2O3, MgO, and Na2O, accounting for more than 90% of the total mass. The phase relations and thermodynamic properties of the CaO-Al2O3-SiO2-FeOx-MgO-Na2O oxide system is highly required, and is of great scientific significance for optimization of vitrification processing and sustainable resource utilization of melting slag. A study on the equilibria phase relations of CaO-SiO2-MgO-FeOx system was done by using CALPHAD method based on FactSage in this paper. The modeling parameters for the thermodynamic properties of liquid phase in CaO-SiO2-MgO-FeOx system were established and the equilibrium phase relations of MgO-SiO2-FeOx and CaO-SiO2-FeOx-MgO systems were calculated for different temperatures and oxygen partial pressures.IntroductionThe main oxide components of vitrified bottom ash slag are CaO, Al2O3, SiO2, Fe2O3, MgO, and Na2O, accounting for more than 90% of the bottom ash by weight [1]. During slag processing and modification, the knowledge of thermodynamic properties and liquidus temperature in the related slag system is highly required [2-5], which is not yet available. Through literature survey [6-9], it is clear that the systematic information on the concerned complex slag system is scarce. Most binary subsystems except FeOx-Na2O have been investigated well. Among ternary subsystems, few phase relations of the Na2O-MgO-SiO2 ternary system are available. For the phase relations of the system Na2O-MgO-Al2O3, all the studies are focused on the Al2O3-rich region. Investigation on the CaO-Al2O3-FeOx system is limited to Fe2O3-containing system with relatively higher oxygen potential. Most quaternary systems are not studied well except the CaO-MgO-Al2O3-SiO2 system, mainly due to their metallurgical importance. Figure 1 demonstrates the research status of the vitrified bottom ash slag with almost zero effort [10]. The effort here is defined based on the published literature by considering the number of publications, the investigated composition ranges, and the research details. So far the engineers in the field have to make assumptions of the thermodynamic properties of the simplified oxide system, without taking into consideration the interactions of the different oxide components, which hinders the development of the slag valorization and utilization. In order to provide thermodynamic properties for the application of the vitrified bottom ash, the six-component oxide system (CaO-MgO-Al2O3-SiO2-FeOx-Na2O) will be investigated through both experimental approach and computer modeling."

Jan 1, 2011