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By Hiroshi Ono

"By newly developed ICP method, trace amounts of As(III), As(V) .,Sb(III) and Sb(V) were precisely determined within accuracy of sub ng/ml. As(III) and Sb(III) were separated from As(V) and Sb(V) by extracting into ·xylene as diethyldithiocarbamate complexes using diethylammonium diethyldithiocarbamate (DDDC), and then back-extracted into nitric acid for a quantitative determiruition by ICP-AES equipped with hydridegeneration system The recoveries of As(III) and Sb(III) were satisfactory throughout the extraction with 0.04mol/l DDDC in xylene from lmol/l hydrochloric acid solution and the back-extraction with 7 mol/l nitric acid. As(V) and Sb(V) were reduced to As(III) and Sb(III) by ascorbic acid and potassium iodide, and their quantities were determined as mentioned above. The detection limits were found to be 0.58ng/ml for As(III), 0.63ng/ml for Sb(III) using 50ml of a sample. The proposed method was applied to analysis of the real sample.Introduction In drain, arsenic(AS) concentration is prescribed below 0.lmg/l, so As must be removed. As is existed at .the form of As(III) or As(V) in solution. For t1Jeir difference of chemic;µ property, it is not easy to remove As in solution. So it is an urgent necessity to develop for determining concentration of As(III) and As(V). Antimony( Sb) has resemblance .chemical property to As. So Sb was experimented the same as As.The separation and determination of As(III) and As(V) have been carried out using several methods, such as ICP after copreclpitating separation, HPLC, direct hydride generation atomic absorption. However these methods have some problems. One of main problems is that HPLC and direct hydride generation atomic absorption methods are influenced by coexisting elements."

Jan 1, 2000

By A. Mikula, S. Karlhuber

"Unique physical and mechanical properties made the Pb-Sn solders attractive for low temperature joining of electronic parts. But since lead in solder materials has become a great enviromental problem and health concern, lead will be slowly replaced by other materials in soft solders. Some of these materials which are currently under investigation are ternary tin alloys. Many different physical properties like wetting behavior, electrical and thermal conductivity and surface tension are measured on these alloys, but on the thennodynamic properties and the phase diagram of the alloys under discussion there is only little information available. We investigated the (Ag, Au, Cu)-Sn-Zn systems and determined the thermodynamic properties over the whole composition range by emf-measurements. From these measurements we also got some information on the liquidus. In the Sn-rich corner the phase diagrams are still under investigation.IntroductionSoldering is technically defined as the joining of two base materials, mostly metals or metal coated nonmetallic substrates, with a third metal. The melting temperature of the third metal or metal alloy should be well below those of the substrates. Solder alloys can be categorized in soft and hard solders. Soft solder alloys usually contain lead, tin, bismuth, indium or cadmium and hard solders gold, zinc, aluminium or silicon. The difference between soft and hard solders is the melting temperature of the soldering material. This temperature is around 350°C.An interesting brief history of solders is given by Vianco and Frear [1]. They report, that in 4000 B.C. solders were already used in Mesopotamia. From archaeoligical evidence those solders were gold-based hard solders.Tin-lead soft solders and their use are not easily found, because in course of time tin has been reduced to stannic acid, making the identification quite difficult. Well preserved soft solder artifacts were discovered in King Tut's tomb dating from 1350 B.C. In ancient time Pb-Sn solders were used primarily for the manufacture and repair of cooking utensils and metal tools. The Romans used lead-tin solders extensively in the construction of the aqueducts."

Jan 1, 1996

By Xin Wang, Hongmin Zhu, Shuqiang Jiao

"The behavior of electrochemically depositing silicon in a molten high-melting-point fluoride electrolyte was studied at 1300 °C. The cathodic product was characterized by XRD, SEM and EDS. Though the analysis of structure and composition of deposition, it could certify that silicon deposited on the Mo rod and alloyed with molybdenum. A series of tests had been performed on the cathodic behavior of Si4+ ions in BaF 2-CaF 2-Na2S iF 6 molten salt. The influence of electrochemical parameters on the cathodic deposition of silicon was also investigated. The electrochemical behavior of Si4+ ions in applied fluoride melts was observed to proceed according to one-step reaction.IntroductionGreenhouse warming has been a serious global issue. lt is increasingly urgent for clean and renewable energy. Effective utilization of clean and inexhaustible solar energy has become very important. Solar cell (especially poly-Si solar cell) production has significantly increased this decade, as there is a growing demand for clean energy. Since the early 1980s, the annual growth of the photovoltaic (PY) solar cell industry is more than 30%. More than 90% of the annual solar cell production is based on crystalline silicon wafers. This rapid growth leads to a shortage of silicon of the adequate quality and price for the continued growth of this industry [I , 2J. The most conunonly used technology to produce silicon is the so-called Siemens process. This technology, involves the forming of gaseous Si compounds such as trichlorosilane (SiHCli) or silane (SiH4) with subsequent thermal decomposition of these back to Si. This technology is associated with transformations from solid to gas, and then back to solid phase, which lead to high irreversible thermodynamic losses and subsequent high energy consumption, the energy cost being around 200kWh/kg Si [3l_ The purity of the material from this process is very high (9 to 11 N). In general, what is needed for solar cell purposes are reported to require 4 to 6 N quality. To promote continued growth of the silicon-based PY industry, there is need for a low-energy silicon production process which can produce large amounts of silicon with an acceptable quality and a lower price particularly."

Jan 1, 2012

By Carlos A. Nogueira

Spent Ni-Cd batteries contain in the electrode materials heavy metals like Ni, Cd and Co, which must be recycled due to environmental problems. Pyrometallurgy is normally used for recycling these end-of-life products, but alternative processes by hydrometallurgy, integrating also physical operations, can be used. Hydrometallurgy seems to be useful, because metals can be efficiently recuperated in chemical forms with commercial value. The economical viability of this recycling process can be improved increasing the treatment capacity, through the application to different types of residues with similar characteristics like Ni-MH and domestic batteries, or other residues containing Ni/Co, like sludges, dusts or spent catalysts. Spent Ni-Cd batteries were first physically processed using shredding and wet sieving operations. Best results were achieved using an output of 6 mm in the shredder and 1.4-2 mm in the physical separation by wet sieving, resulting a fine fraction containing 70% of the initial electrode material and only 6% of the initial scrap. The acid leaching of the obtained material in the previous operation was studied, being the parameters like: temperature, H2SO4 concentration and the liquid/solid ratio (L/S) optimized. The values attributed to the factors which concerned the best results obtained on the leaching process were mainly influenced by Ni recovery. In opposition, Co and Cd were easily leached in a wide range of conditions. To attain an overall recovery, with minimum costs, of the three metals, the values of T~100ºC, [H2SO4]=2.3-2.7 M and L/S=8-10 L/kg were considered the most appropriate.

Jan 1, 2006

By Entov Vladimir M., Gilmer R. Burgos, Andreas N. Alexandrou

"Processing of metal alloys in their mushy state represents a new trend in metal processing. As part of this process, known also as thixocasting, a specially prepared slurry at a temperature in the mushy region is injected into a die. Parts produced using this technology offer better mechanical properties than those produced by casting, and comparable to those of forged alloys.In thixocasting, semisolid slurries are highly concentrated suspensions of rounded rosette-like crystals in eutectic liquid. The mechanical behavior of the slurry is determined by the structure and properties of the skeleton formed by the alpha phase particles. The skeleton structure is almost never at equilibrium, and its evolution is, governed by a number of kinetic phenomena of different c11'aracteristic time-scales. Therefore, the skeleton structure depends on the mechanical and thermal history of the material. As a result of these kinetic processes, the rheological properties of the material, such as effective viscosity and yield stress, decrease with structure breakdown, and increase with its development. In the present investigation, the behavior of semisolid slurries during processing is modeled using the conservation equations, and a Herschel-Bulkley fluid model. The rheological parameters are assumed to be functions of the solid volume fraction, and of a structural parameter that changes with processing history. The evolution of the structural parameter is described by a first order kinetic differential equation that relates the rate of build-up and break-down of the solid"

Jan 1, 2000

By Yong-ming Chen, Chao-bo Tang, Yun Li, Long-gang Ye, Sheng-hai Yang, Hao-tian Xue

In order to achieve high recovery of Cu and Co during cobalt-bearing copper sulphide ore smelting process, reducing agent (coke) and sulphidizing agent (pyrite) were added into molten smelter slag for reducing-sulphidizing smelting to product Cu-Co matte. Effects of reductive atmosphere, pyrite dosage, smelting temperature and smelting duration on Cu, Co, Fe distribution behaviours were investigated. The results show that the distributions of Cu and Co are mainly enriched in Cu-Co matte, and the distribution ratio, LCu and LCo, improve with increasing of coke amount or pyrite addition, whereas above 6 wt.% coke or 20 wt.% pyrite, Cu and Co tend to transfer from matte to cleaned slag. A properly high temperature(1300) and smelting duration(3h) are beneficial to the enhancement of the distribution ratio of valuable metals, and under the given set of conditions, LCu > LCo generally. However, an undesired high Fe contents in matte limit further increase of LCu and LCo.

Jan 1, 2015

By Wei-ling Wang, Ryosuke O. Suzuki, Xiang-ning Meng, Miao-yong Zhu

"A finite-element thermal-stress model of continuous casting mold is conducted to predict deformation of copper plates and its change with different cooling structure. The results show that deformation behavior of copper plates is mainly governed by cooling structure and thermal- mechanical conditions, deformation amount is related to structure geometry, and a small deformation mutation occurs in cooper-nickel boundary due to different properties. The maximum deformation of hot surface centricities of wide face locate at 100 mm below meniscus and that of narrow face locate at meniscus and terminal of water slots and significant curvature fluctuations on both sides of copper-nickel boundary. The maximum deformation of centricities is increased up to 0.05 mm with thickness increment 5 mm of copper plates, and maximum deformations are only depressed 0.01 mm and 0.02 mm with increments of 1 mm nickel layer thickness and 2 mm water slot depth respectively.IntroductionIn conventional continuous casting of steel, a large amount of sensible and latent heat of molten steel dissipate in primary cooling zone and make continuous casting mold under enormous heating load giving rise to thermal stress, deformation, high-temperature fatigue and creep not only depress mold life-span, but reduce casting stability [1] Many studies focused more on heat transfer, solidification and shrinkage of solidifying shell to provide inverse proposals for optimizing cooling system and even designing new taper of mold [2,3], but it is generally useless to those of having been manufactured or being put into production. Therefore, mold-related forward problems show necessity to be discussed deeply, and stress and deformation distributions based on special thermal conditions in mold should be analyzed in order to explore suitable cooling structure of mold directly. Samarasekera et al. [4] examined heat flow and distortion of two-dimensional longitudinal sections and investigated effect of cooling water velocity, copper plates thickness and carbon content on formation of rhomboidity and longitudinal comer cracks. O'Connor et al. [5] developed a three-dimensional mathematical model to compute thermo-mechanical state in thin-slab mold and calculated temperature and deformation of mold wall to assess roles of various process parameters on impacting mold life. Thomas et al. [6] predicted temperature, distortion and residual stress in mold and indicated increased distortion requires increased remachining, which reduces mold life and increased residual stress increases the probability of a catastrophic crack failure. Park et al. [7l determined heat-flux profiles in funnel-shaped and parallel thin-slab molds based on an inverse heat conduction model and thermocouple temperature measured in-plant and put them into three- dimensional finite-element thermal-stress model to predict temperature, distortion and residual stress of mold wall. Korie et al. [SJ focused on prediction of temperature, distortion and residual stress in mold and in particular to clarify that mold life is significantly affected by temperature and its rigidity, but little effect by mechanical including clamping force, bolt prestress, friction and ferrostatic pressure. Meng et al. [9l predicted temperature and thermal stress in a slab mold and analyzed effect by cooling system geometry and casting speed quantitatively. In present study, a three-dimensional finite-element thermo-mechanical model with type-switched element is transformed from previous heat-transfer finite-element model [9l, and mold deformation is simulated in order to shed light on thermo-mechanical behavior with special thermal conditions and different mold geometry at high casting speed."

Jan 1, 2013

By Wang Dawan

During the process of arsenic bearing gold concentration biooxidation, the content of chloride ion in water is a very important factor to the activity of bacteria and the oxidation of sulfide minerals. In this paper, the influence of underground mine water with different chloride ion content to the biooxidation of arsenic bearing gold concentration and the limit of chloride ion content to bacteria were summarized. These results indicated if the content of chloride ion was less than 1.2g/L, the bacteria?s ability to oxidize sulfide minerals was little affected, and if the content of chloride ion were increased to 2g/L or more, the activity of bacteria was seriously restrained, and if the content of chloride ion were increased to 4g/L, the activity of bacteria was absolutely restrained. So, as the content of chloride ion in water was cumulated to 2g/L or more in biooxidation plant, the water must be refreshed to maintain normal production.

Jan 1, 2008

By Liping Li

A comprehensive three-dimensional two-phase mathematical model was developed to represent a channel type reactor with intense bottom gas agitation. Tracer dispersion and particle tracing methods were used to conduct the analysis based on the solution of the Navier-Stokes equations. Different operational parameters, such is gas volume flow rate. bubbler separation aspect ratios and liquid Input flow rates, were investigated for the purpose of reactor optimization. The numerical calculations were compared with experimental results obtained at the University of Missouri and a good general agreement was observed. Relatively low longitudinal mixing was observed characterizing the system as a "plug-flow" type reactor, in contrast to the intense vertical mixing, under the conditions investigated. Some general mixing characteristics are also discussed In connection to the behavior of other metallurgical reactors.

Jan 1, 1996

By T. Manlyama

The Tamano Smelter of Hibi Kyodo Smelting CO., Ltd. went into operation in 1972. The Flash Smelting Furnace that was originally adapted was equipped with electrodes that were attached to the settler substitute of the slag cleaning furnace. Later the development of our own original coke combustion technology was promoted and a new Tamano Type Flash Smelting Furnace (T-FSF), without electrodes, was put into operation in 1988, T he technology of coke combustion and combustion the burner have continued to improve. As a result the copper losses in the Wag have been reduced as well as a stable operation has been achieved, Furthermore; this has been accomplished while increasing the concentration feed and the matte grade. The current objective is to continue to strive for high matte grade operation and to raise production efficiency while paying attention to the important subject of copper losses in the slag. In this report, the data related to the copper loss in the slag reduction are presented along with the influence of the thickness, settling time and coke. The recent operation conditions of the T-FSF are also presented.

Jan 1, 2003

By Waraporn Piyawit

Grinding sludge from the sintered neodymium-iron-boron (NdFeB) magnets production process was enriched with critical rare earth elements (neodymium, dysprosium and praseodymium), which can be up to 30% in the magnets. The demand of NdFeB magnets are simultaneously growing. Therefore, rare earths recovered from waste residue would reduce the demand of rare earth elements from primary sources. In this study, the feasibility of recycling rare earths through a hydrometallurgical process was investigated. The selective leaching of Nd from grinding sludge can successfully raise the rare earths concentration to 70%. The necessity of an oxidation pretreatment to improve the selectivity between Nd and Fe will be described.

By Zhiqiang Han, Anil K. Sachdev, Baicheng Liu, Guomin Han, Alan A. Luo

The growth of precipitate phase ,B-Mg11Al12 in Mg-Al alloy is closely related to interface anisotropy and elastic interaction. The aim of this work is to investigate the effects of the interface anisotropy and elastic interaction on the morphology evolution and growth kinetics of the precipitate. In the work, the precipitation of ,B was studied using phase field modeling. In the model, the chemical free energy of the precipitate and the matrix were obtained via thermodynamic calculation. It is demonstrated that the interface anisotropy results in lath-shaped precipitate and the elastic interaction affects the shape of the end of the precipitate. The interface anisotropy causes uneven growth in different directions and the elastic interaction influences its preferential growth orientation. By combining the interface anisotropy and elastic interaction in the phase field modeling, the results showed that the precipitate phase has a lath-shape with lozenge ends, which is in agreement with experimental observations.

Jan 1, 2013

By Yuanbo Zhang, Xiaoming Mao, Zhixiong You, Zhenyu Fan, Tao Jiang

"It is generally known that the formation of calcium ferrite is favorable during the iron ore sintering, which dominatingly contributes to the improvement of strength and reducibility of the finished sinters. In this study, effects of roasting temperature and 02 content of inlet gas on the sintering mineralization properties of typical iron ores, including hematite, limonite, specularite and magnetite, were investigated. The results showed the amount of calcium ferrite initially increased then decreased with the increase of the roasting temperature. The temperature of maximum calcium ferrite generation amount for different iron ores was determined as follows: hematite and limonite was 1275 °C, whereas specularite and magnetite was 1250 °C. Increasing 02 content of inlet gas was advantageous to the generation of calcium ferrite during the sintering. The sequence of 02 content affecting the mineralization properties of different iron ores was determined as follows: magnetite > hematite > specularite > limonite.IntroductionThe mineralization property of iron ore plays a significant role in the mineral composition and microstructure of finished sinters, which determine the quality and output of the sinters [1-2]. The mineralization process of sinters is composed of solid-phase reaction, formation of liquid-phase and crystallization. The formation and crystallization of liquid-phase is the foundation to the mineralization as the quality of the sinter is poor when concreted by solid-phase consolidation [3-4]. With respect to the iron ore sintering, liquid-phase regarded as bonding phase is generated between the iron ores and fluxes at high temperature [5]. Calcium ferrite is the most favorable liquid-phase among the bonding phases which dominatingly contributes to the improvement of strength and reducibility of the finished sinters [6-8]. Especially for high iron-low silicon sintering and high basicity sintering, making sure sufficient calcium ferrite quantity and reasonable distribution is crucial to the sinters [9-10]. Therefore, carrying out the researches on the high temperature reaction properties of iron ores is of great significance [11]."

Jan 1, 2013

By David E. Hardt

"One of the critical variables to be controlled during arc welding is the size or geometry of the weld pool. The measurement of pool geometry has become an increasingly important problem with the advance of welding automation and control, and this paper addresses that problem. The basic concept of pool size estimation via measurement of pool dynamics is presented. The theory underlying this concept is discussed and is followed by a review of the current work in this area. It is concluded that pool dynamics can be characterized by natural frequencies of oscillation, for stationary welds, and that these can be measured by appropriate signal processing performed on the arc voltage. However, it appears that only full penetration welds show a strong correlation between weld size and natural frequency. Also, the extension of these results to the realistic case of moving welds has yet to be considered in detail. Nonetheless, this method of in-process measurement for real-time weld process control is still quite attractive where applicable since it can be accomplished simply by modifying the arc current schedule and by signal processing of the arc voltage.INTRODUCTUIONThe study of welding process control has been dominated by research into methods of in processing sensing of the weld pool geometry. While it has been shown feasible to measure the topside pool geometry using video methods [1,2], the penetration or backside bead width have remained elusive quantities. This is particularly true if a topside sensor location is required.The concept of using weld pool motion as a pool geometry sensing method was proposed by Hardt et al. [3] and later demonstrated by Hardt and Zacksenhouse [5] and Richardson and Renwick [6]. The concept is based on the fluid dynamics of a pool constrained by a solid container and by significant surface tension forces (i.e. a small shallow pool, not a ""pond"" or ""lake""). Such a pool, if subjected to external forces, will exhibit a surface motion is a function of that force, the properties of the fluid, the surface tension, and the shape of the container. Thus, if this motion can be excited and measured, and the relationship to the pool geometry determined, a means of sensing pool shape will exist."

Jan 1, 1986

By Romeo U. Pagador

After privatization in 1999, PASAR Corporation initiated a plant modernization program to optimize the performance of the smelter by increasing plant availability. This initiative required operational adjustments to the converting and anode furnace procedures, to support the higher throughput in the flash furnace, while continuing to meet government environmental regulations. The major shift in production direction was to eliminate the 30-35 day maintenance shutdown every two years, and replace it with a 15-day shutdown. This paper discusses the changes implemented in the converter and anode operation that have resulted in an increase of 10% in flash furnace throughput, an 18% increase in blister output, to 170 tonnes per cycle, and a converter campaign tonnage increase of 10%. Since privatization, PASAR has instituted a series of ?management of change? programs that have facilitated an industrial cultural change needed to achieve the company?s vision, mission and strategic goals.

Jan 1, 2005

By Y. Ide, K. Kishitake

It is expected that an Al-Cr-N composite nitride film may have a higher resistance to oxidation at elevated temperatures than the well-known Ti-Al-N films. The formation conditions of Al-Cr-N films by a de reactive sputtering method and their properties were studied in this study. The films characterized with respect to their high temperature properties such as chemical composition, crystal structure, microhardness, wear and· friction. The crystal structure of the Al-Cr-N films changed from hexagonal phase to cubic phase with an increase in Cr content in the films. The resistivity to thermal oxidation of the Al-Cr-N films is superior to that of usual TI-Al-N films. A half of the friction coefficient in the Al-Cr-N film was obtained comparing with that in the ordinary TI-Al-N film at room temperature and the wear rate of Al-Cr-N film was 2 order smaller than that of TI-Al-N film. The Al-Cr-N films show a small friction coefficient at 500°C and then they are recognized to have good tribological characteristics.

Jan 1, 2000

By Kazuhiro Asai

Hitachi Refinery of Nippon Mining & Metals Co., Ltd. installed a reverberatory type recycling fumace in 1978 in order to treat the industrial wastes which contain metal elements such as copper, gold and silver. Pyrite and industrial waste materials such as galvanizing sludge, hydroxide slime and dust are smelted. Sulfidized copper, iron and precious metals are transformed into matte and other metallic elements are oxidized into slag This copper matte is transported to Saganoseki smelter and copper and precious metals in the matte are recovered. Recently it is difficult to obtain pyrite economically because of the decrease of pyrite production. Therefore, a new treating process of the liquid waste has been investigated at Hitachi Refinery. In this process, the sulfide or sulfate from the liquid waste are smelted as a source of sulfur.

Jan 1, 1997

By Varadarajan Seshadri

The performance of mould fluxes in satisfying its quality requirements can have a significant effect on the efficiency of the continuous casting process and on the surface quality of the products. This performance is affected by various parameters including the characteristics of the mould fluxes, the quality of the steel being cast and the operational conditions of the caster. The extremely complex relationships involving the parameters mentioned above make it very difficult to have simple criteria for selecting mould fluxes for casting a certain grade of steel in a continuous casting machine. These difficulties led steelmakers and mould flux suppliers to select mould fluxes based mainly on plant trials. In the present work, a software to help in the analysis and development of mould fluxes for continuous casting was developed. This software includes several models for prediction of mould flux viscosity and consumption. A mathematical model was also used to predict the heat flux through the mould flux. The proposed methodology was applied to continuous casting of crack sensitive steels. Some of the results given by this software are presented, discussed and compared to plant data.

Jan 1, 2003

By Carl A. Kuehn

At Carlin, Nevada, non-indigenous hydrocarbons were introduced as a bitumen phase which was mobilized due to burial under the Roberts Mountains allochthon. similarly, some indigenous organic matter was locally mobilized. Fluid inclusion and paragenetic data of veinlets formed during this hydrocarbon stage, combined with quantitative modelling or organic maturation, indicate that host rocks had evolved past dry gas conditions of around 1550 and l.l+0.2 Kb in the presence of CH4-saturated, highly saline brine by no later than early to middle Cretaceous time. All hydrocarbons present would have been rendered immobile under these catagenic conditions. Crosscutting relationships at several scales suggest that hydrocarbon mobility may have ceased prior to the intrusion of a series of dikes in the mine which have subsequently been altered and mineralized. Apart from subsequent oxidation, the current distribution and high maturity of carbon-rich zones were established prior to gold introduction. No Evidence has been found supporting proposed hydrocarbon "remobilization" during or after gold mineralization and alteration. The high density of the CH4-bearing fluid requires formation at high pressures (near 1 Kb) and precludes their formation as a result of the "cracking-off" of CH4 from organic matter during a thermal event associated with a shallow hydrothermal system. The density and composition of the fluid inclusions restricted to the early hydrocarbon-stages of the Carlin paragenesis are not unique to the sediment-hosted gold deposit environment of north-central Nevada. Similar inclusions are found in authigenic quartz crystals from Paleozoic carbonaceous shales in central Pennsylvania which have experienced normal metagenesis of indigenous organic matter due to deep burial.

Jan 1, 1987

By Courtney Young, Jerome Downey

"The various technologies developed for treating spent potlining (SPL) from primary aluminum smelters have been reviewed on several occasions. The technologies generally involve physical, chemical, and thermal processes, either individually or in combination, with the primary objective of total recycle, waste minimization, or complete disposal. In general, those technologies geared for recycling involve separations and are therefore subject to recovery inefficiencies that are attributed to several factors. However, the inefficiencies could be reduced or possibly eliminated if the pots were designed for recyclability. This concept is applied to SPLASH, a recently developed SPL management technology.IntroductionAluminum is produced by molten salt electrolysis via the Hall-Héroult process. The process is conducted in an electrolytic “pot,” which is comprised of a steel frame first lined with insulating refractory brick, and then conductive graphite blocks, which serves as the carbon cathode [1, 2]. These materials are collectively referred to as “potlining.” Anodes comprised of petroleum coke/pitch are suspended above the pot and extend down into the molten cryolite (Na3AlF6) electrolyte. The electrolyte temperature is maintained at approximately 980 °C by resistance heating as low voltage (4-5 volts) and high current (50,000-300,000 amps) are applied across the two electrodes.High purity alumina is added to the cryolite bath, where it dissolves and becomes amenable to aluminum reduction at the cathode:"

Jan 1, 2008