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By W. D. Judge, Z. W. Xiao, G. J. Kipouros

Rare earths have taken a prominent position in the Hi-Tech field after the discovery of the NdFeB permanent magnets. Their use in the magnets sparked miniaturization of the communication devices such as computers and mobile phones and are being considered in many more applications. Potential applications of rare earth elements in energy conversion technologies including wind turbines, photovoltaics, and other renewable energy systems are reviewed, along with sustainability considerations and production processes.

Mar 1, 2017

By A. Alvarez

In this work, mesophilic and thermophilic cultures have been used in the presence of silver as a catalyst. Chalcopyrite and byproducts of bioleaching were characterized in order to: a) obtain information about the kinetics control of the process, and b) explain the different behaviour observed during the mineral attack. With thermophilic microorganisms (68°C and Norris medium as nutrient) the reaction stopped at approximately 65% copper extraction, with and without Ag ion addition as a catalyst. The remaining chalcopyrite appears surrounded by hydronium jarosite (with ammonium ion in substitution in the "alkaline site"), goethite and elemental sulphur. With mesophilic cultures (35°C and 9K medium as nutrient) the reaction stopped at approximately 25% copper extraction (without Ag) and approximately. 85% extraction (with Ag). In both cases, the remaining chalcopyrite was surrounded by agglomerates of ammonium jarosite (with hydronium ion substitution in the "alkaline site") and some iron oxides and/or hydroxides.

Jan 1, 1999

By Nozomu Hasegawa

The phase diagrams and microstructures of the slags in the Mitsubishi Continuous Copper Smelting and Converting Process were studied for the prevention of the magnetite troubles such as accretion build-up on furnace hearths and launders, blockages at the melt outlet, slag viscosity increases and so on. According to the results of those studies, the silica and lime contents in the silicate slag at the smelting furnace, and the lime content in the lime-ferrite slag at the converting furnace were changed, resulting in lower and more consistent copper levels in the discard slag, with much less need for operators to clean melt outlets and launders. However, these changes may decrease the desirable amount of accretion-coating inside the furnaces and thereby reduce furnace campaign lives. Therefore, a method of estimating the magnetite level in the melts was developed, and slag compositions and temperatures have been controlled within the appropriate ranges to prolong furnace lives and also prevent magnetite troubles.

Jan 1, 2003

By M. Okido, H. Yamamoto, T. Sakamoto, R. Ichino, K. Kuroda

"Hydrogen absorption alloy films have been produced by molten salt electrolysis. Lanthanum-Nickel alloy film can be formed on a nickel substrate in KCl-NaCl-LaCb molten salts by electrolysis diffusion process. LaNi5 alloy was formed by mutual diffusion between La ·and Ni after La deposition on Ni substrate. Though several kinds of La-Ni compound existed in deposits, the alloy compounds on Ni substrate changed by electrolysis condition. According to the open-circuit potential measurement in molten salts after La electrodeposition, the formed compounds had a relation to the potential. In the case of the substrate electroplated a cobalt thin film on nickel, LaNi4_5Co0.5 was formed by the electrolysis in the molten salts with lanthanum ions. This ternary alloy film showed better hydrogen absorption behavior in cyclic charge/discharge test in alkaline solution.IntroductionHydrogen storage alloys have attracted attention as the active materials for batteries with the charge/discharge property at ambient temperature. The alloy of nickel and misch metal, mainly consisting of La and Ce, has been commercially 'used as a metal hydride with rechargeable property. In recent years, researches have been developed many kind of new alloys with better hydrogen absorption properties. The hydrogen absorbing alloy ingots are commonly produced by melting method of both metals in furnace, otherwise, prepared by mechanical grinding and metallurgical sintering technique with metal powders. The film is also made by vapor-phase techniques such as sputtering method, ion plating method, etc. ·We have proposed a new method to produce hydrogen absorbing alloy films by molten salts electrolysis technique [1-3]. The hydrogen absorbing film, LaNi5, Mg2Ni and CaNi5, were obtained in this process through controlling the electrolytic condition. The active metals, La, Mg and Ca, are electrodeposited on Ni substrate, diffuse into the substrate and form various kinds of intermetallic compounds. This technique provides a direct process using metal chlorides as resources to produce functional films without using active metals such as La, Ca and Mg."

Jan 1, 2000

By Jian Yang

The mechanism of resulfurization in the desulfurization process with magnesium vapor produced in situ by aluminothermic reduction of magnesium oxide was clarified in the present work. The influences of various operating parameters on the resulfurization were studied and the methods that could prevent resulfurization were proposed. There are two kinds of mechanisms of resulfurization in the desulfurization process with magnesium. One is decomposition of the desulfurization product of MgS under the inert atmosphere. The other is oxidation of MgS under the oxidative atmosphere. Under the present experimental conditions, lowering operating temperature and oxygen partial pressure in the atmosphere could effectively prevent the resulfurization. Adding CaO onto the melt surface was an effective method for preventing the resulfurization due to transformation of the desulfurization product of MgS into the more stable compound of CaS. Since addition of the activated charcoal powders greatly decreased the transfer rate of oxygen in the atmosphere to the melt surface, it also reduced the resulfurization remarkably.

Jan 1, 2006

By R. Lanza, M. Hytros, N. Saka, I. Jureidini, J. H. Chun, D. Kim

"A novel method for delineating the solidification front in metal casting has been developed using the attenuation phenomenon of electromagnetic radiation (y-rays or x-rays) and computed tomography (CT). The densities of the liquid and solid phases that exist during metal casting may differ anywhere from 4 to 12 % depending on the metal. As in the medical imaging field, CT provides an excellent means of mapping this density variation in a solidifying casting into two-or three-dimensional images.In an effort to develop an industrial-scale sensor, laboratory-scale experiments have been conducted using a cobalt-60 (Co60) radioisotope and a sodium-iodide (Nal) scintillation detector. The CT image reconstruction was performed on a crucible containing pure tin in a two-phase state. Although the spatial resolution and data acquisition speed were not optimum, the CT images clearly differentiate the liquid and solid phases of the tin in the crucible. To maximize resolution and minimize data acquisition time, a linear accelerator (linac)-based CT sensor is being developed and tested for application in the continuous casting of steel and aluminum alloys.IntroductionIn all casting processes, the quality of a finished product and its production rate depend upon the shape and movement of the solidification front. From a quality perspective, it is well documented that solidification kinetics (heat and mass transfer, fluid flow, microstructure evolution) greatly influence the final properties of castings [l,2,3]. Product shortcomings, such as surface defects, cracks, macro-and microsegregation, and inclusions are directly controlled by the solidification process. By understanding the role the solidification front plays in the casting process, product quality may be dramatically increased through the reduction of defects."

Jan 1, 1997

By Yuanyuan Wang, Yuhao Ding, Hao Bai, Kang Zhou, Guangwei Du

"In this paper, the list analysis of GHG emissions of aluminum industry was conducted based on the data from typical electrolytic aluminum plants of a China’s northwest province. The results show that under the conditions of average anode effect coefficient as 0.16 times/(cell• day) and anode duration as 5 minutes per day, equivalent emissions of CO2 reached 1.23 ton per ton of aluminum, in which PFC emissions accounted for about 71%. Compared with foreign advanced level, which is 0.87 ton per ton of aluminum under the conditions of average anode effect coefficient as 0.01 times/(cell•day) and anode duration as 0.46 minutes per day, there is much room for China’s aluminum industry to reduce GHG emissions. Since anode effect plays an important role on PFCs generation in electrolytic aluminum process, how to control anode effect strictly becomes the key factor for remarkable reduction of GHG emissions in China’s aluminum industry.IntroductionTechnology of aluminum electrolysis is a mature and efficient process of aluminum production. Due to the huge demand on aluminum worldwide, so resource consumption, energy consumption and pollutant emissions in the process of aluminum production are still large. The global output of aluminum reached 45193 kt in 2012. A large amount of CO2 and PFCs are produced in the process of aluminum production, and the greenhouse effect and environmental pollution caused by emissions of them is a concern. PFCs belong to a powerful greenhouse gas, thus emission reduction of PFCs is very important for aluminum electrolysis industry. At present, China's aluminum production accounts for about 33% of the world's aluminum production, and controlling PFCs emission has become the key point of pollution control of aluminum electrolysis industry in China [1].Taking the case of a typical electrolytic aluminum plant of a China’s northwest province, this paper studies the list analysis of GHG emissions of aluminum industry in China. GHG emissions of a China’s northwest province were calculated through investigating existing situation of aluminum electrolysis industry in the province, knowing capacity, output, main production technology and equipment level of aluminum electrolysis industry, and using the calculation framework and methods of GHG emissions of aluminum electrolysis industry, which were put forward by the intergovernmental panel on climate change (IPCC), the international aluminum association and other organizations at home and abroad. The list analysis of GHG emissions of aluminum electrolysis industry will offer useful information in promoting emission reduction of GHG in aluminum electrolysis industry, improve the efficiency of energy utilization."

Jan 1, 2014

By Gabriel Riveros, Ariel Balocchi, Andrzej Warczok, Daniel Smith

Blister copper from converting of copper matte is processed by fire refining prior to electrorefining. The fire refining consists of two steps: copper oxidation with impurities slagging and copper reduction. The classical batch process is carried out in vascular or reverberatory furnaces called anode furnaces. A new process for continuous copper fire refining has been proposed. The copper flows through two reactors in cascade, where is oxidized and reduced. The flow of a liquid copper through a ceramic packed bed increases the surface area and the rate of oxidation as well as the rate of reduction in the packed bed of charcoal. Mathematical modelling allowed for the design of a laboratory scale demonstration installation and industrial-pilot installation in Hernan Videla Lira Smelter (Paipote). The results have demonstrated the process feasibility and flexibility in operation.

Jan 1, 2009

By Elizabeth M. Ho

Oxidants are added in uranium leaching in acid media to convert iron(II) in solution to iron(III). Iron(III) has an important role in the leaching of uranium by acting as an electron transfer agent for the oxidation of uranium(IV) to uranium(VI). The oxidation of iron(II) to iron(III) in sulfate solutions using sulfur dioxide/oxygen (SO2/O2) was carried out under typical uranium leaching conditions (pH 1-2, 20-50°C) to confirm literature trends and this work was then extended to the use of SO2/O2 in the leaching of uranium ore. The oxidation rate was found to be dependent on the initial SO2/O2 volumetric ratio and the oxygen mass transfer rate, but was independent of the initial iron(III) concentration above about 200 ppm at pH 2. The presence of 55 ppm organic extractant (Alamine 336) decreased the reaction rate. The oxygen mass transfer coefficient (kLa) for the mixing tank system was measured and was found to decrease with increasing solids density in a 1 g L-1 MgSO4.7H2O solution.

Jan 1, 2003

By D. N. Wilson

The potential risks of working with lead have been recognised for centuries, but it is only with the development of sensitive measuring techniques in relatively recent years that it has been possible to establish effective approaches for the monitoring and control of lead exposure. This paper examines the principal control measures employed today - lead in air and lead in blood - and reviews the evolution of numerical standards, with particular reference to the latest understanding of health effects. In addition to lead, a large number of other metals are commonly encountered when producing lead and zinc - both primary and secondary - and the health effects of many of these are discussed. Modern hygiene practices and technologies, which have proved successful in reducing worker exposures, are reviewed. The paper concludes with a look at how exposure standards are likely to change in the near to medium future

Jan 1, 2000

By Xie Zhang, Jiang Diao, Xiaojun Li, Bing Xie

"Vanadium is widely utilized as an important element to improve the quality of alloyed steels in iron and steel industry. Moreover, the crystallization process of V-containing spinels plays a significant role due to the aim of achieving a fairly larger size of spinel crystals in vanadium extraction. Thus, a comprehensive exploration and discussion on the competitive precipitation and growth of vanadium, chromium and titanium spinel crystals in vanadium slag during a cooling process were carried out in the present study on the basis of a crystallization kinetic model. To be more specific, the abilities of forming crystal, precipitation order and suitable temperature range for crystallization of the three kinds of spinels were discussed with both theoretical and experimental methods.IntroductionVanadium is an important element which is used almost exclusively in ferrous and non-ferrous alloys due to its excellent physical properties such as high tensile strength, hardness, and fatigue resistance [1]. Various kinds of processes of vanadium extraction from V-containing hot metal are available at present. However, only four processes which are the Highveld process (South Africa), the Pan-steel process (China), the NTMK duplex process (Russia) and the New Zealand steel process (New Zealand) take the dominant positions [2, 3]. Although the type of reactor and the initial vanadium content in hot metal are different in these techniques, they share the same principle that vanadium is oxidized by oxygen into vanadium slag."

Jan 1, 2012

By David C. Lynch

The molecular form of trace elements in matte has been shown to depend on the chemical potential of sulfur and the propensity of the trace element to form a sulfide. Of the four trace elements (As, Sb, Bi and Pb) arsenic and lead behave nearly as opposites, with lead readily forming a sulfide while arsenic forms complexes with free copper and ion in the matte. Antimony and bismuth both display the dissolution characteristics as As and Pb, suggesting that these elements dissolve in matte in multiple forms of significant concentration. While in the present investigation the dissolution characteristics of all four trace elements are examined, the primary focus is on the multiple dissolution behavior of Sb and Bi.

Jan 1, 1995

By Toshiyuki Kawai

Copper concentrate smelting directly in P-S converters was started at Onahama Smelter in 1983. Thereafter, the tonnage of concentrate smelted through the P-S converters increased, such that by 2002, it equaled the tonnage smelted through the reverberatory furnaces. In 2003, 56% of the total copper concentrates treated at Onahama Smelter were processed directly through the P-S converters. Technical improvements are reviewed and advantages of direct smelting in P-S converters are reported.

Jan 1, 2005

By Jian Li, Pei Liu

In recent years FIB has become a powerful instrument to perform ion beam sectioning and site-specific TEM specimen preparation. However, there are still gaps in understanding FIB-induced artifacts. Gallium ion beam damage and specimen heating during FIB milling can produce unwanted artifacts during FIB work.Calculations ofmaximumspecimentemperature increaseshavemostlybeen based on the assumption that ion beam implantation into substrate of infinite size. This deviates from finite specimen volume in FIB TEM specimen preparation that impedes specimen heat dissipation. In this paper, the authors will demonstrate a few commonly observed FIB artifacts, and discuss the concerns of specimen temperature rise during FIB milling process.

Mar 1, 2017

By Wenya Du, Qingbo Yu, Peng Li, Qin Qin

"A new heat recovery system is proposed. This system uses the endothermic heat of gasification reaction instead of sensible heat to recover the energy of molten blast furnace slag. The gasification technological parameter in molten blast furnace was calculated and the exergy of the system was analyzed. The gasification reactions were studied kinetically by the isothermal thermogravimetry using STA409PC thermal analyzer. The results showed that, according to different gasification agent, this system can produce syngas with different C-H ratio. The exergy efficiency of this system is high and its internal exergy loss rate is about 11%. This method can bring huge economic and environmental benefits which are important to the survival and sustainable development of iron-steel enterprises. The molten BF slag acts as not only thermal media but also good catalyst. The kinetic parameters on gasification reaction with different types of coal used differ from each other.IntroductionEnergy consumption in the iron-making process is about 50%~60% of the total energy input. The blast furnace is very important in the iron & steel process. So energy conservation and emission reduction about blast furnace is very important. In recent years, in order to recovery energy, many new technologies such as TRT (Top gas pressure Recovery Turbine) and CCPP (Combined Cycle Power Plant) were used in iron-making. But the energy of molten blast furnace (BF) slag has only been used limitedly so far.Molten BF (Blast Furnace) slag is the byproduct of iron-making at the high temperatures range from 1723 to 1923K, and has a large amount of sensible heat remaining. The yield of molten BF slag is about 300 kg per ton of pig iron. In conventional processes, molten BF slag is quenched rapidly using a large amount of water to produce a glassy-granulated slag. The quenching slag must be dried before it can be used in cement manufacture. During the process, a large amount of water was consumed and the energy of molten slag can not be recovered. At the same time, it causes environmental pollution problems. So the critical problems of the process are not only energy recovery of molten slag and reducing emission of H2S and SO2, but also guaranteeing the subsequent use value of slag. For this propose, many new technologies were investigated to recover the thermal energy of molten slag. The promising methods are dry granulation [1-4] and reforming of methane [5-9]. The method, utilization of reaction heat instead of latent heat and sensible heat, is quite attractive from viewpoints of energy storage without heat loss, and makes a connection to other industry. But both of them are in laboratory. In this paper, coal gasification in molten BF slag was used to recover the energy of molten BF slag. The gasification technological parameter in molten BF was calculated and the exergy of the system was analyzed. The gasification reactions were studied kinetically by the isothermal thermogravimetry using STA409PC thermal analyzer."

Jan 1, 2011

By P. T. Velu

Light weight aluminum alloys are the major construction materials for a number of structures in automobile and aerospace industries. Higher cost of production is the key impediment which restricts the usage of these alloys. A new electrochemical process route for the low cost production of aluminum alloys is being investigated, in which alloying elements are obtained from the dissolved compound. In the present investigation, solubility of lithium compound has been determined by measuring the EMF, when it is dissolved in the electrolyte. The solubility of Li2CO3 increased with temperature from 2.95 wt pct at 1063 K to 7.57 wt pct at 1093 K. Activities of the compound in the electrolyte were deduced using Temkin's ideal solution approach.

Jan 1, 1995

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

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

Jan 1, 2000

By M. Cowling, S. Kumarl, A. W. Piper, R. A. Forsdick, C. Bailei, M. Patell

"The lead-refining process takes place in hemispherical vessels called kettles. In these kettles, lead-bullion is mixed at a certain temperature to remove impurities from the melt. This paper presents steps in a novel method for calculating vortex shape and flow field in the refining kettle using Computational Fluid Dynamics (CFD). First of all a two-dimensional axisymmetric model is used to calculate the vortex shape at the liquid-air interface. Here action of impellers and baffles are accounted for by adding source and sink terms to the appropriate momentum equations. The model includes Yolume of Fluid (YOF) method to predict the shape of interface deformation, i.e. vortex. This strategy reduces the computationally intensive three-dimensional transient simulations to a more efficient two-dimensional model. The calculated vortex shape is then used to regenerate a full three-dimensional grid. This grid is used to carry out steady-state simulation using the standard multiple-reference-frame method of impeller-fluid-baffle interaction within the commercial code Fluent. Simulation results for both stages of the development are compared with experimental data.IntroductionOne of the most important steps in Lead Refining process is impeller stirred mixing of Lead Bullion in hemispherical vessels. During this process, the melt is treated with one or more reagents in order to remove impurity elements such as copper, antimony, silver and bismuth. These impurities react selectively with the reagents and float to the melt surface in the form of a powdery layer, which is then skimmed for further processing. Figure-! shows (a) the lead refining kettle and (b) the schematic representation of involved flow pattern. Stirring of the lead bath using specific impeller designs, which creates a central vortex, provides a mechanism for draw-down and dispersion of the buoyant reactants. Clearly, effective control of the impeller generated vortex and flow pattern is crucial to achieving efficient operating conditions."

Jan 1, 2001

By Henry Hu, Alfred Yu

"A numerical model has been developed to simulate heat and mass transfer phenomena occurring during a novel magnesium reduction process-the vertical retort technology. The model was based on the control - volume finite difference approach. Simulations were run to determine the effect of various processing parameters on magnesium reduction cycle time. The model predicted temperature distributions, heating curves, recovery ratio of magnesium, and total process times. The predictions were used to optimize the magnesium reduction process including dimensions of the retort, geometries of the reactant compounds, and productivities. The results indicate that the implementation of the optimized processing parameters significantly decreases the reduction time, and consequently increases the production rate as well as lowers the energy consumption.IntroductionMagnesium consumption has been growing considerably in the past decade [1]. Of the total magnesium production, 30% is produced by the thermal reduction (Pidgeon) process, and it is anticipated to be still the main technology for producing magnesium in future [2]. One of the advantages of the Pidgeon process is that it is capable of producing high purity magnesium demanded by both the automotive and aerospace industries. However, the inefficiency of heat and mass transfer taking place in the horizontal Pidgeon reduction process results in low productivity, high energy consumption, labor-intensive operation, large floor space and high capital investment. This limits the production scale of a horizontal Pidgeon reduction process [3].Vertical reduction processTo overcome the shortcomings of the horizontal magnesium reduction process, a novel vertical magnesium reduction process [3] for large-scale production has been developed, in which heat and mass transfer in the retort is enhanced. The new process shortens reduction time, reduces energy consumption and increases productivity. The vertical reduction system is comprised of a vertically-placed retort, a heating furnace and a vacuum system. A section of the vertical retort is illustrated in Figure 1. Since the retort is set vertically, instead of horizontally, the entire procedure of loading the reactants material in the new process is different from the one for the horizontal reduction process."

Jan 1, 2001

By Yue Yu, Hangyu Zhu, Jianli Li, Di Wang

Thestainlesssteelslagastheby-productofsteel-makingplantscontains 2–10 wt% Cr O , and the potential elution of hexavalent chromium impedes the 2 3 utilization as a secondary resource. The reduction of chromium oxide in steel- making slag containing Cr O by FeSi at 1550 °C was investigated in the labora- 2 3 tory. The experiments were performed in a carbon-tube furnace, and the samples collected during tests were analyzed using X Ray Fluorescence (XRF) and Scanning Electron Microscope (SEM) equipped Energy Dispersive Spectroscopy (EDS). The results show that the FeSi addition could efficiently enhance the reductionandrecoveryofchromium.WhentheamountofFeSirangedfrom2upto 9 wt%,therecoveryincreasedfrom65.60%to84.19%.Theoccurrenceofresidual chromium was metal particles, which dispersedly distributed in silicate phases owing to the size limitation. The sufficient FeSi could easily reduce chromium oxidesintometal,butthecriticalfactorofchromiumrecoveryistheprecipitationof suspending metal particles from the molten slag. Thus, some measures should be proposed in order to make sure that the suspending particles are adequate to aggregate into bigger ones. (cid:1) (cid:1) (cid:1) (cid:1)

Mar 1, 2018