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By Thomas J. O'Keefe, Pu Yu, George Houlachi, Xuewen Tang

"Impedance measurements were used to investigate the electrochemical characteristics of acidic zinc sulphate electrolytes containing Sb3+, gelatin and their mixtures. The data were correlated with cyclic voltammetry curves made using synthetic as well as industrial electrolytes. The cyclic voltammetry results were similar to those obtained in previous studies in that antimony caused a depolarizing effect while gelatin gave an increase in the potential for zinc nucleation on an aluminum substrate.The electrochemical impedance spectroscopy (ElS) evaluations were conducted on electrodeposited zinc at three overpotential values. The potentials were chosen to represent various current density regions in the zinc polarization curves. The antimony and gelatin gave characteristic impedance plots which correlated with expected behavior, particularly current efficiency. Both antimony and glue appear to modify the intermediate zinc reaction sequence, but in different ways. The data strongly suggest that film formation and stability are major factors in the zinc ion reduction mechanism.IntroductionThe zinc electrodeposition process is sensitive to the presence of a variety of organic and inorganic chemical species in the electrolyte [I]. Such components can produce either beneficial or harmful effects, depending on their relative concentrations and electrochemical behavior. Extensive investigations have been made to gain a better understanding of the changes occurring during zinc deposition in the presence of such additives. Techniques employed include microscopy, x-ray diffraction, dynamic voitammetry, current imd energy efficiency studies [2-5]. Ultimately, the objectives are to identify the factors which most affect the efficiency of the process and to provide a means to effectively control them.One of the most harmful impurities is antimony, which can be detrimental when present at concentrations as low as 10 to 20 parts per billion. Dramatic changes in zinc polarization behavior, deposition structure and current efficiency have been observed with antimony in the electrolyte. Antimony appears to lower the hydrogen overpotential by hydride formation or a similar catalytic mechanism, which allows an increase in localized corrosion and zinc dissolution [6-8]."

Jan 1, 1997

By Norihisa Iida, Yutaka Koshiba, Tsutoipu Masui

"Mitsubishi Materials has many years of experience in the production of oxygen free copper (OFC) and its alloys with a fully continuous-casting process. Four grades of OFC, commercial, electronic, superconductor, and ASTM class I are available according to user needs such as stabilizer for superconductivity, magnetron, and ultra-vacuum systems. Along with Cu-Ag and CuSn, we offer OFC based copper alloys such ·as Cu-Cr-Zr, Cu-Fe-P, Cu-Ni-Si and others, that are suitable for lead frame and connectors. Within the maximum sizes of 260mm X 1050mm for cakes and 385mm diameter for billets, we are very flexible and can adjust the ingot size to customer’s requirements. Other products that we can supply are semi-finished products such as hot rolled sheet, ·forged blank, extruded rod and finished products like mold for continuous casting of steel, ring mold for non-ferrous casting and backing plate for sputtering target.IntroductionMitsubishi Materials Corporation developed mass produced high quality oxygen free copper and. high copper alloy ingots in the 1960's. We produce 60,000 - 70,000 tons annually giving us 22 - 23% share of the world's market.Our oxygen free copper and. copper alloys are produced with a fully continuous casting process using only high-grade copper cathodes from our Naoshima and Onahama refineries. The raw material is melted and cast in' a carefully controlled atmosphere resulting in a product with low impurities and excellent properties.Using a controlled atmosphere it is possible to produce high quality copper alloys including active elements like chromium (Cr), zirconium (Zr), titanium (Ti), and magnesium (Mg) which are difficult to produce using standard batch casting methods.Using our own cakes and ·billets we produce and supply worldwide wrought materials like molds for ferrous and non-femous casting. These products receive special patented thermo-mechanical· treatments resulting in high strength and excellent conductivity with low cost."

Jan 1, 2000

By Toshiyuki Hiranami, Keizou Uematsu

"AbstractionSpray freeze drying method was proposed to fabricate ·ceramic: powder granules for high performance ceramics. Obtained granules and their green compact were characterized by SEM and immersion liquid technique. Granules have a spherical shape of about l 00 µ m in diameter, ·and no binder segregation was found with the immersion liquid technique. The granule had sufficient strength for usual handling, while the strength was much lower than that of granules prepared by conventional spray-drying. Unlike the conventional green compacts, granule interfaces were not observed in the green body made with the spray-freeze dried granules.IntroductionIt was well kn9wn that spray-dried granules have binder segregation layer on their surfaces. The trace of this segregation layer survives in the later processes i.e. compaction and firing, and behaves as fracture origins in the sintered bodies. The origin of this problem is solvent drying process from slurry droplet surface in spray drying system. As alternative method we propose a freeze drying process for granule preparation, in which solvent is remove by sublimation though the process, binder segregation can be prevent.In this study, we applied spray freeze drying method to fabricate alumina powder granule, and characterized the obtained granules, and their green compacts and sintered bodies.Experimental procedure.Alumina powders and additives aqueous solution were mixed for 24 hours using a ball mill to· prepare the slurry for spray freeze drying. .The solid loading of the slurry was 30vo1%. Deflocculant (PAA-NH4 type) was added 0.5mass%, and the binder (PVA). 1.0, 2.0 or 3.0mass% of alumina. Obtained slurries were sprayed into liquid nitrogen to make frozen granules. The granules were freeze dried.For the characterization of the granules, immersion, liquid technique observation and single granule strength test were carried out. Strength of individual granule wa5 measured using micro compression testing machine (MCTM, SHIMADZU). Granule strength was calculated from following equation."

Jan 1, 2000

By Kikuo Okuyama, I. Wuled Lenggoro, Manabu Shimada

"Aerosol processing of materials such as (i) gas-to-particle conversion process (e.g., Chemical Vapor Deposition (CVD) method) and (ii) liquid (or droplet)-to-particle conversion process (e.g., spray pyrolysis) has become of major interest to produce novel submicron- or nanometer-sized particulate material used in electronic and chemical industries. After reviewing recent theoretical and experimental researches on the evaluation of properties and morphology of fine particles by the CVD and spray pyrolysis methods, the importance of the process engineering approach· for aerosol processing of materials and the use of advanced aerosol measurement technology have been pointed out.IntroductionMaterial synthesis via aerosol processing offers a route to producing nanometer-sized and submicrometer-sized particles of high purity with specifically tailored chemical and physical properties. Especially, single nanometer-sized particles (nanoparticle materials) are considered to play an important role in the synthesis of nanostructured materials as well as in nanotechnology in 21st century due to their quantum effect and so on.However, the transformation of gaseous or liquid precursors to the final functional particulate matters consists of various complex chemical and physical processes. In order to control the size distribution and morphology of produced particles, it is important to analyze and model various phenomena, such as gas-phase or liquid-phase chemical reaction, nucleation, condensation, agglomeration and sintering that occur simultaneously in aerosol material processing. By introducing the Aerosol Science and Materials Science, the authors have been trying to model the changes in particle properties and morphology by gas-to-particle conversion and droplet-to-particle conversion processes. The authors have also been trying to obtain the experimental data on the particles properties as accurate as possible."

Jan 1, 2000

By Norihiko Fukatsu

In order to use effectively the previously reported new sensing system for hydrogen and oxygen potentials in molten copper, the criteria of the potentials for getting sound castings have been determined in the laboratory experiment. The copper melt equilibrated with a given hydrogen and an oxygen potential was rapidly quenched in the crucible. The relations between the holding potentials and the gas porosity in the solidified sample were investigated by measuring the density of the sample and microscopic observations. It was found that the defects of the gas porosity became the maximum at the potentials where the dissolved amount of hydrogen and oxygen was in the mole ratio 2: I. The samples having the density more than 99% of the theoretical value were obtained in the higher oxygen and lower hydrogen potential region or in the lower oxygen and higher hydrogen potential region. The criteria thus determined were examined by comparing with the measured potentials in the practical easting machine. In tough-pitch copper casting, the problem due to gas porosity was found to be serious when the hydrogen potential increased. In the oxygen-free copper casting, the evolution of hydrogen was found not avoided. The gas porosity in the casting, however, was found eliminated when the oxygen potential was kept at a low value.

Jan 1, 2003

By M. Vijayalakshmi, S. Saroja, C. Sudha, T. N. Prasanthi

"Ti-5Ta-2Nb alloy and 304L austenitic stainless steel were joined by explosive cladding process. Investigations on 'as received' explosive clad revealed high hardness very near the interface due to martensitic transformation of 304L steel base plate. To improve ductility, explosive clads were heat treated in the temperature range of 823 to 1073 K for 1 to 20 h. Consequent change in the microstructure and microchemistry of the clad interface was studied. No change in the interface microstructure was observed for heat treatment at 823 K. Increase in temperature lead to the formation of various reaction zones at the interface, their number and width increase with temperature and time of thermal exposure. Growth kinetics of the reaction zones was monitored and activation energy required for formation was calculated. From elemental redistribution profiles, effective inter-diffusivities of alloying elements were calculated as a function of concentration and activation energy required for inter-diffusion was evaluated.IntroductionFor engineering components exposed to highly oxidizing and corrosive environments, a titanium based alloy i.e Ti-5Ta-2Nb (Ti-Ta-Nb) is often chosen as a structural material [1,2]. For economic consideration, vessels and piping exposed to non-oxidizing conditions are fabricated from 304L austenitic stainless steel (304L SS). Hence, dissimilar joint of Ti-5Ta-2Nb alloy and austenitic stainless steel becomes unavoidable. Fusion welding processes are not suitable for joining Ti and Fe based alloys due to the propensity for the formation of intermetallic phases and subsequent reduction in the bond strength [3,4]. Hence, explosive cladding, a solid state welding technique, was used to achieve high integrity, corrosion resistant joints between the two alloys."

Jan 1, 2012

By R. A. Masumura, C. S. Pande, D. Agassi

"Grain size has a different effects on the critical current density (Jc) of high and low transition temperature (Tc) superconductors. In high Tc superconductors, the critical current density Jc across grain boundaries depends sensitively on the misorientation 8. It was pointed out by Pande that this dependence is directly related to dislocation structure of the grain boundaries i.e., it is due to dislocation cores and stresses. These ideas are developed further in this paper leading to a relation between Jc and 8. The analytical result is compared with the experimental results on bicrystals and used to explain the difference in behavior between high and low Tc superconductors.IntroductionThe grain size distribution and its evolution with time and temperature is important in determining the properties of high and low transition temperature (T c) superconductors. The distribution is a convenient function to characterize the processing of a high Tc material during sintering. For example, it is known that the maximum density of ceramic materials is obtained when the grain growth is reduced but grain boundaries are still mobile. For practical superconductors, the processing parameters are selected to achieve optimum properties: highest possible T c and maximum critical current (Jc). In terms of an average grain size, the requirements for optimum T c and Jc are sometime in conflict. In A15 type superconductors and even in NbTi, larger Jc have been measured in smaller rather than larger grain sized material. Conversely, in a high Tc materials like YBa2Cu307, higher Jc have been found in larger grain sized or single crystal specimens.Extended defects such as grain boundaries in low T c superconductors can be effective pinning agents for magnetic flux lines, thereby increasing the transport critical current density of these materials [1]. On the other hand, the transport critical currents in polycrystals of high Tc superconductors such as YBa2Cu307 is found to be relatively small (much smaller than those in single crystals of the same material) [2]. It is now known that grain boundaries in high Tc polycrystals can in many cases form ""weak links"" reducing the critical current density across them. This phenomenon can be studied more precisely by experiments on bicrystals, where there is only one grain boundary. It is found that the critical current density is quite sensitive to the misorientation angle of the bicrystal [3,4]. Although the original experiments were conducted on YBa2Cu307, other Tc superconductors have been shown to give the same result [5]."

Jan 1, 1994

By Viktor Mukhin

"Among the methods proposed for spent activated carbon regeneration, the most acceptable is, thermal reactivation, because in this case the existing equipment for manufacture of activated carbon can be adapted for this purpose.In order to conduct the process of thermal re-activation of spent activated carbon directly at gold mills, a fullscale drum-type furnace with external electric heating has been developed, i.e. EPV-300 model with a throughput rate of 50 to 120 kg/hour. Its use ensures restoration of the adsorption properties of carbon up to the level of fresh activated carbon with an insignificant (by 0.7%) decrease in strength and with a high (95% to 97%) yield of reactivated carbon.During the recent years, activated powder carbon has been extensively used in flotation processes for treating polymetallic ores at ore treating plants to improve recoveries of main metals (copper, lead, nickel, etc.).Especially large volumes of activated powder carbon are used at the Talnakh concentrator of the Norilsk Mining and Metallurgical Complex in Russia for absorption of residual flotation reagents from recycled water in order to ensure efficient selective separation of minerals with similar physical and chemical properties.IntroductionSorption technology based on active carbons use starts being applied in such an important in the widest sense of the word strategical branch of economics as non-ferrous metallurgy. Thus since the middle ninetieth Russian gold extraction industry began to apply widely the processes of sorption from pulps and solutions by means of high-resistant granulated active carbons. That provided the start of gold ore minefield exploration, increasing of gold extraction from the ore and reducing its loss with the ""tails"" of process. At present more than 40% of Russian gold is extracted with the help of sorption technologies [1].Another field of active carbons application in non-ferrous metallurgy is the processes of non-ferrous ores floatation at ore-mining and processing enterprise. For that purpose powdered (less than l00µm) active carbons are used for providing the effective selection of minerals with similar physicochemical properties. This method not only increases the metal extraction level but provides deeper division of them."

Jan 1, 2008

By Andrey Tarasov, Erki Unn, Valery Paretsky

"The stability of the markets of energy resources and labor in countries of the Baltic Sea Region including Estonia is determined to a significant degree by the use of combustible shales as fuel and their distillation resulting in generation of up to 70% of non-recyclable waste. The objective of this business plan is to substantiate the investments for establishment of a new facility in Estonia for waste-less and environmentally safe processing of fossil minerals and man-made products generated in the shale industry, as well as other hazardous wastes. The proposed facility will use a basically new waste processing technology developed in Russia - i.e., processing in sparged molten slag This technology eliminates any release of harmful pollutants to the environment and a facility using this technology does not require, therefore, any sanitary protection zone.IntroductionIn the Baltic region, and first of all in Estonia and some other European territories, there are large natural deposits of combustible shale, which due to the lack of other own resources of energy and hydrocarbons for the chemical industry is burned and distilled with low technical and economic efficiency generating large amounts of toxic and highly toxic wastes and intermediate products. Currently, the penalties for disposal of such wastes have grown to such an extent that shale burning and distillation might become unprofitable. This might result in suspension of the given operations, which in turn will affect in an adverse way the markets of energy resources and labor market in those countries. Furthermore, in addition to the “shale problem”, Estonia, similarly to most member countries of the European Union, faces the challange of environmentally safe processing of highly toxic wastes, such as municipal solid wastes, oilpolluted materials, medical wastes and infected materials, spent rubber tires, etc. These wastes are at present stored or processed with release of a significant quantities of extremely toxic cancerogenic substances (dioxins, furans) or collected and exported for treatment at an extremely high cost and with a loss of valuable components contained in these types of waste and often with return of supper toxic processing products."

Jan 1, 2008

By E. Ilgar

"Deposition studies were conducted in acid copper electrolyte to determine the influence of chloride ions on cathode morphology. A statistically designed screening test was carried out in the absence and presence of 20 ppm CI- using a three factor, two level factorial design, in an electrolyte containing 36 gl'! Cu2+ and 150 gl-! H2S04, The independent variables evaluated were agitation; current density and temperature and their influence on surface roughness was determined. The copper deposited at current densities where activation was the primary control mechanism appeared similar in morphology whether stirring was used or not. The addition of 20 ppm CI- to the electrolyte gave rougher deposits under the same conditions. In the mixed control regions, considerably rougher, dendritic deposits were obtained when CI- was present. Agitation was effective in reducing the copper surface roughness both in the apparent activation and mixed control regions in the presence ofCI-. The results of this study showed that 20 ppm Cl- polarized the copper deposition at low overpotentials but caused depolarization at higher overpotentials.IntroductionChloride ion is inherently present in copper electrolyte, either as an additive or from other sources such as make up water. The behavior of the chloride ion is well documented in electrorefining operations, but its role in copper winning is less obvious. However in both cases there is evidence that cathode growth and solution chemistry are strongly influenced by its presence. The mechanism and electrochemical action of the Cl"" have been shown to be very complex, therefore a better understanding of its influence on electrocrystallization is essential for improved cathode deposit growth control. It was proposed that Cl"" polarizes the copper deposition reaction at low concentrations due to CuCI formation but depolarization occurs at higher concentrations due to the formation of a soluble CuCI2"" complex [1,2]. Franklin [3] reviewed the mechanism of additives in the electrodeposition process and proposed that the Cl"" complexed with copper, adsorbed on the cathode as an induced anion leading to an increase in the reduction rate. At cathodic overpotentials less than 100 mY, lppm NaCl had a polarizing effect, i.e. an increase in impedance of the charge transfer step. At higher Cl"" concentrations up to 100 ppm, depolarization occurred as evidenced by a decrease in impedance, which was attributed to soluble cuprous complexes [4]."

Jan 1, 1997

By N. Mizutani, S. Harada, Z. Asaki, T. Tanabe

"The development of lead-free solders is urgent in view of environmental standpoints. In this -work the wettability of tin-bismuth- silver solders on copper was studied. Three kinds of fluxes were used. The wettability of conventional eutectic tin-lead .solder exhibited an excellent level over the other solders of tin-bismuth systems. Poor wettability of the tin-bismuth solders may be caused by the growth or dendritic copper-tin compounds at copper/solder interface, in contrast to the case of tin-lead'· solder. The wettability was improved by the addition· of silver in the solder. In this tin bismuth- silver system, silver was abnormally concentrated at the copper I solder interface even in the initial stage of contact. The wettability of the solder and the thickness of compound formed on the copper have a good correlation; the solder containing 2% silver exhibited the best wettability and the formation rate of copper-tin· compound on the copper was slowest.IntroductionSocial demand to avoid lead use in the industrial fields has been recently promoted· (1) because of the environmental protection of water resources. Especially the lead-bearing solders have been widely used in electronics and automobile products, and it is urgent to replace them with nontoxic materials (2)-(4). Thus the development of lead-free solders becomes an indispensable subject to the new generations and many works (5)(6) have already been carried out on the research and development of new solders. New lead-free solders are expected to have some requirements, for example, moderate melting temperature, proper strength and integrity, and lower prices, as compared with conventional solders. There have been already several alloy systems developed. Among ·these alloy systems, tin-bismuth binary or tin-bismuth-silver ternary alloys have great advantages such as having a wide range of soldering .temperature by controlling con:ipositions, though they have such disadvantages as ""lift-off"" (7)-(9): It is said, on the other hand, that a frequently overlooked property of solders, or one that is typically ignored by the research scientist as an ""issue"" for the manufacturing or product engineer, is wettability (10), although a ·work on the wettability has recently been published (11). In this Work, therefore, the authors selected Sn-Bi-Ag solders and focused mi the effect of Ag-addition to wettability of the solder."

Jan 1, 2000

By Gordon A. Irons, Diancai Guo

"Uneven movement of scrap during melting in an Electric Arc Furnace causes operation problems: cave-ins interrupt electric power input. The movement also influences the radiation heat loss to water-cooled side panels and roof. An apparatus has been built to simulate the flow of scrap that may be interlocked. It has been observed that flow starts at the point where the suspended length of the pile bottom reaches the average scrap size, and proceeds in the form of cave-ins, but scrap pieces slide with each other as ordinary granules. After a cave-in, the pile angle usually remains much larger than the normally observed angle of repose. The force balance of a partially suspended scrap pile has been analyzed, and the equivalent cohesion due to interlocking estimated. A numerical model has been developed to simulate the scrap flow. Simulated results agree reasonably with observed phenomena.IntroductionWhen one considers the melting of steel scrap in an electric arc furnace (EAF), it is helpful to understand the movement of the material during meltdown. As industrial experience demonstrates, scrap movement greatly affects EAF operation. In a typical operation, scrap is dropped into the furnace from scrap buckets. The roof and electrodes are swung into position, and power is applied to the electrodes situated over the scrap. The electrodes ""bore"" into the scrap by melting into the steel in the immediate vicinity of the electrodes as they are lowered. If solid scrap pieces gradually slide towards the arc area, the electric power supply can be maintained at a high level, with few interruptions or drastic electrode adjustments. This results in a high production rate and low power consumption per tonne of steel produced. On the other hand, if the charge moves down unevenly, i.e. in large surges, usually called cave-ins, the electrodes must be drastically raised, and power supply frequently interrupted. This is also accompanied by a high level of harmonics induced in the power network, deteriorating the quality of electricity supplied to other users.In addition, the movement of scrap in an EAF also influences the furnace heat efficiency, as the scrap pile is much closer to the electric arcs compared to the furnace wall and roof, and absorbs more radiated heat. Early exposure of the wall and roof to the arcs will increase the heat loss due to radiation, and reduce the service life of the furnace."

Jan 1, 2004

By Jorge Alberto Soares Tenório, Denise Crocce Romano Espinosa, Viviane Tavares Moraes

"The development of mobile phone technology has increased the replacement of outdated equipments for more modern models, transforming disposal of such devices into a serious environmental problem. Recycling appears as an attractive alternative to minimize the environmental impact of disposing such large quantities. Recycling can be accomplished by treating the printed circuit boards of used mobile phones by using the same techniques used in ore treatments with hammer mill; magnetic separation, electrostatic separation and grain size range. Before performing the recycling process a PCB characterization was performed to identify the fraction with the higher metals concentration/content. This study demonstrated that the electrostatic separation was not the best metals concentration of PCB aiming the recycling, while the non-magnetic residue had presented a more significant metal concentration. Furthermore, after the magnetic separation was possible to separate the following metals: iron and nickel.IntroductionPortable electronic devices have gained increasing acceptance over the last decades. Mobile phones sales in Brazil, for instance, have reached 104 million in 2007, and 128 million in 2008. It is estimated that, around the world, 100 million mobiles are thrown away every year, either because of loss of functionality or because newer models are launched in the market [1,2, 3]. Printed circuit boards in mobile phones are made of many materials, with approximately 83% in weight being metals and fiber-glass, and the balance being plastics pl. Several metals can be recovered from the electronics waste, such as copper, tin, iron, lead, nickel, titanium, aluminium as well as some precious metals such as gold, silver and palladium [4, 5, 6, 7, 8]. Concurrent with the increasing world demand for copper, there average metal content in ores has been decreasing. Economically interesting copper mines used to have 4% metal content, whereas presently, such content is around 1%, i.e., for every 1 ton of ore extracted, only 10 kg are copper [9, 10]. Approximately 33% of printed circuit boards (PCBs) composition is copper, that is, for every 1 ton of PCBs waste, 330 kg are copper [1]. Research in recycling PCB waste focuses on mechanical, electrometallurgy, pyrometallurgical and hydrometallurgical processes [3, 8]. Collecting and recycling obsoletes electro-electronic equipments is very important these days, in order to, not just preserve the non renewable natural resources but also to keep the environment and the population safe from the pollution caused by the toxic materials and heavy metals present in this kind of waste."

Jan 1, 2011

By Masatsugu Morimitsu, Tian Zhang

"This paper presents a novel anode for oxygen evolution in acidic aqueous solutions to produce non-ferrous metals by electrowinning. The method to prepare the anode was thermal decomposition of a precursor solution, and the obtained anode consisted of Ru02-based oxide catalytic layers formed on a titanium substrate, in which the catalytic layer contains nano-oxide particles as the active component. The oxygen evolution potential was lower than amorphous lr02-Ta20s coated titanium anodes so that the cell voltage of electrowinning was further reduced with the amorphous Ru02-based electrode.IntroductionElectrowinning (EW) is used to produce high purity of non-ferrous metals, and the primary metal production of copper, zinc, nickel, and cobalt by EW consumes huge electric energy worldwide, which tends to increase with increasing demand of such metals. The reduction of electric energy consumption is a significant issue for electrowinning industry, which means that the cell voltage reduction is needed to realize more energy-efficient EW processes. Another issue is also indicated from environmental perspectives; i.e., an improvement in EW plant environment by eliminating hazardous byproducts and wastes. Such byproducts and wastes include lead oxide, manganese oxide, and acid mist.We have been developing the anodes for energy-efficient and environmentally friendly electrowinning processes [ 1-11]. The development has been successfully done with the invention of the smart anode, MSA TM (Morimitsu Smart Anode) [ 1-5], which has low polarization for the main reaction and high polarization for the side reaction, in which the main reaction is oxygen or chlorine evolution, while the side reaction is the anodic deposition of each or both of lead oxide, manganese oxide, and cobalt oxide. The anode consists of a valve metal substrate coated with amorphous or less crystalline oxide catalytic layers. One of the typical examples of such oxides is amorphous lr02-Ta20s, and the substrate is normally titanium plate or mesh. The most important point of the oxide is that the amorphization or less crystallinity induce the increase in the active surface area only to the main reaction, not to the side reaction, thereby the polarization of the main reaction being reduced.In this paper, we present the smart anode consisting of RuO2-based catalyst formed on titanium substrates for oxygen evolution in electrowinning. The preparation, characterization, and polarization behaviors of the anodes are shown, and the cell voltage data for zinc or copper electrowinning using the anodes are also presented."

Jan 1, 2012

"Mineral flotation processes are often characterized by long dead times and slow process dynamics. The process dynamics change due to different ore types, feed grades and circulating loads. These are some of the factors that can make control of flotation processes difficult. Implementation of adaptive control algorithms at Brunswick Mining has made controlling these processes feasible. The role of adaptive controllers in plant optimization and the overall control philosophy is discussed.IntroductionBrunswick Mining is located just outside of Bathurst, New Brunswick, Canada. The concentrator processes approximately 10,250 tonnes per day of ore that assays at approximately 8.9 %Zn, 3.6 %Pb, 0.3 %Cu and 100 gram/tonne of Ag. The four products produced are zinc concentrate assaying 51 %Zn, lead concentrate assaying 36 %Pb, copper concentrate assaying 21 %Cu, and a bulk concentrate assaying 32 %Zn and 18 %Pb.The original flotation process control system, supplied by Outokompu Oy of Finland, was replaced in the summer of 1988 by a Provox system supplied by Fisher Controls Inc. The Provox system consists of two redundant integrated function controllers (IFC's), two operator console stations with two screens each and a Digital Equipment Co. microVax II computer running Fisher's Computer Highway Interface Package (CHIP).In January 1989 a boiler management package, which includes the boiler control hardware and another operator's console, will be added to the Provox system. In late spring of 1989, a Vax 3200 computer running G2 artificial intelligence software from Gensym Corporation will be installed. These devices are all connected using a redundant data highway that runs around the plant.The primary measurement devices in the flotation circuit are two Courier on-stream X-ray analyzers. The Courier systems each have 14 sample cells with two streams multiplexed into each cell. Each pass of the on-stream head takes approximately 6 minutes yielding a nominal sampling interval of 12 minutes. The Courier passes its assays to its respective IFC. The IFC handles the digital and analog I/O, DDC and cascade loop control, some low level calculations and sequencing. The CHIP microVax has 9MB of memory and 220MB of mass storage running under the VMS operating system. The CHIP microVax is a central database for the Provox system. It is used for data trending, metallurgical modelling and balancing, instrumentation database, long term storage, and on-line adaptive assay control."

Jan 1, 1989

By John A. Mavrogenes

The Texaco gasification system developed at the Monte Bello pilot plant efficiently bums petroleum-coke thereby producing syn-gas and electricity. This system produces more electricity than conventional burners, yet the only by-products are pharmaceutical grade sulfur and V -rich slag. Vanadium is known to exist in multiple valence states in compounds which possess a wide range of melting points and physical properties. Consequently, it becomes important to carefully regulate oxygen fugacity throughout the system in order to control vanadium valence state. Vanadium phase equilibria is presently poorly understood, in large part because of the multiple oxidation states of vanadium (-I, 0, +2, +3, +4, and +5) and the difficulty of unequivocally identifying the valence state(s) in many compounds. The operation of these gasifiers at approximately 1400°C is well above the melting point of V20S but considerably below the melting temperature of V02 and V 203. If J02 can be regulated to keep the burner within the V 205 field, slag material would more likely remain molten and more easily flow out of the bottom of the burner. In pure V oxides. the oxidation state is readily determined by microprobe analysis. where V20S (V+5) is 56% V, V02 (V+4) is 61.4% V, and V203 (V+3) is 68% V. However, V valence in multi-element phases (especially phases containing other elements of variable valence) cannot be resolved by microprobe analysis alone. Petroleum-coke gasification slags collected from within the gasifier under different oxidation conditions were studied by electron microprobe analysis (EMPA). X-ray diffraction (XRD). X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Raman spectrometry in conjunction with microprobe analysis was found to resolve the valence of vanadium in the phases of these slags. Raman spectra collected from homogeneous single phase V-oxide standards in vacuum at low temperatures (-150°C) yielded peaks characteristic to each valence state. Gasifier slag samples are, however, much more complicated. Oxidized samples contain: fine grained (Ca. Mg, Fe. V) oxide matrix of variable composition, (Fe. V, Ni) spinel. (Fe, AI, V, Ni, Mg) spinel, V205laths, AI-Si glass blebs and Ni sulfides. Reduced samples contain: crystalline Ca-siIicate matrix, subhedral to euhedral (V, Fe, Mg, AI) spinel, subhedral V02, Fe and Fe-Ni sulfides, Fe-Ni alloys, and complex Ca-oxide matrix. The different spinel assemblages, the characteristic V-oxides and the distinctly different character of the matrices makes the oxidized and reduced slags readily discernible.

Jan 1, 1995

By H. P. Wang, E. M. Perry

"Analytical solutions for investigating the solidification of casting problems with initial superheat and natural boundary conditions have been derived using an integral method. There are two moving interfaces in the solution field, one for the phase change line and the other for the superheat line. Two coupled nonlinear differential equations, representing two moving layers, were calculated by the Runge-Kutta numerical integration scheme. The solutions are in terms of six dimensionless parameters: phase change number, two Biot numbers for interfaces, diffusivity ratio, and dimensionless superheat temperature and time. Parametric studies on these parameters have been conducted to provide generic information about this phase change problem. This analytical information is extremely useful for validating numerical solutions. A simplified I-D finite element model was constructed for the purpose of comparison. The excellent agreement between the analytical and finite element solutions has proven that they are mutually validated.This validated finite element modeling tool was then used for modeling an investment casting process of a super-alloy with a simple geometry: a two-step plate. The nonlinear latent heat release, a common property of alloy materials, was approximated by several piecewise linear segments. The transient temperature response of this 2-D finite element solution, including a metal/mold gap resistance, shows excellent agreement with experimental data.This fundamental work provides a solid basis for further work on the development of a process modeling tool for the complex investment casting process.IntroductionAt present, the investment casting process is used in a variety of industries. In the aircraft engine industry, in particular, investment casting is used to produce parts ranging from turbine blades to engine frames. Because a large single casting can replace many component parts that require machining, fabrication, and assembly, this one-piece casting approach becomes a very cost-effective manufacturing process.The main constraint in using this process for mass production is the long design-to-production lead time. The standard rigging design is still an art, based on the experience of casting experts, rather than on scientific methods. Many trials are often required before making a sound final casting. In order to .reduce the number of expensive casting trials, the development of computer-aided tooling technology is needed.The fundamental physics describing this manufacturing process can be simply described. They reduce to a solid/liquid phase change problem, with two parts - first, the thermal balance of the initial superheat temperature of the molten metal and the preheat temperature of the ceramic shell through heat conduction, and second, the energy release from the mold surface to the ambient by radiation."

Jan 1, 1986

By P. Tapp, T. Evans, N. A. Molloy, J. Lucas

"Consideration of the protoype tuyere geometry for injection of inert gas through the bottom in a basic oxygen steel furnace and a requirement to specify an optimal flow for bottom wear and metal penetration led to experimental investigations[l,2] to apply the results of previous workers to this specific case, Flow velocity profile development within the tuyere was proposed as significant and the experimental scheme was designed to test this. It is proposed that the design criterion for the conditions of optimal flow of the prototype geometry be based on the non-dimensional mass velocity.INTRODUCTIONSharma[3] tested small diameter tuyeres in a laboratory hot model using molten iron to define a flow criterion for prevention of penetration of the bath liquid into the tuyere. Using argon, nitrogen and helium through a range of tuyeres (1 to 3 mm ill ) he proposed the jet Froude number C Fr' ) with the critical value being 2400 - 2500 or higher. Sonic or supersonic velocity was not a sufficient criterion. The tuyere design was a parallel tubular duct of moderate aspect ratio CAR) i.e. the ratio of length to diameter ranging from about 22 to 36 in the experimental furnace.Farmer et al[4] stated their their aim ""to develop a unifying explanation and procedure for the proper design of tuyeres"" but disagreed with Sharma's jet Froude number criterion. Recalculating Sharma's data they proposed instead a fully expanded Mach number of 1.75 with an initial expansion angle of ten degrees as the lower bounds of flow to meet the design requirement. They experimented with tuyeres in a water model using tubular, annular and convergent-divergent nozzles. The aspect ratio of the parallel duct tuyeres was from 533 to 762 using diameters of 1.4, 1.7 and 2.0 mm C the diameters being of tubes to be used full scale). Subsequently these results were applied to a prototype tuyere using a diameter of 1.7 mm with beneficial results in practice. This tuyere had an aspect ratio of 1067."

Jan 1, 1996

By M. Cassir

"The unique properties of molten carbonates offer a large scope of applications in the field of energy. In effect, these molten salts are in the center of chemical and electrochemical reactions involving carbon and carbonaceous species, carbon dioxide and carbon monoxide, significant for energy generation or even for the production of fuels. Moreover, such media have also an oxidative character; they dissolve molecular oxygen and oxygen reduced species, O 2-, O22- and hypothetically o-, which may have an important role in waste treatments, homogeneous catalysis and synthesis of oxides. In this presentation, an overview will be given on the principal physicochemical properties of molten carbonates, before focusing on their main known application, the molten carbonate fuel cell (MCFC). Progress in other new fuel cells applications will also be analyzed, such as direct carbon fuel cell (DCFC), hybrid carbon fuel cell (HDCFC) and composite high-temperature fuel cells combining the features of MCFC and solid oxide fuel cell (SOFC). Afterwards, membranes for the separation and capture of C02 will be reviewed. Finally, other topics, as the oxidative coupling of methane in molten carbonates, will be briefly mentioned.IntroductionIn the thirty past years, the molten carbonate science and advances have been mainly dedicated to the understanding and optimization of the molten carbonate fuel cell (MCFC), which is still a major issue in the heart of a new vision of energy development. More recently, new topics related to other kinds of fuel cells (DCFC, composite SOFC/MCFC systems) and C02 capture have emerged and are concentrating important research and technological efforts. Moreover, new fields of implementation, related to molten carbonates, are also present: geology, glasses, production of nanocarbon particles etc. Considering other areas where this molten phase plays a major role, such as catalysis, waste destruction, surface treatment, it can be confirmed that the field of molten carbonates is very rich and offers many opportunities for fundamental science and competitive applications. Whatever their specific application, molten carbonates activity is associated to more efficient energy systems with low production of C02 and, in a prospective sense, to non-polluting energy using the value of C02. A recent event, the International Workshop on Molten Carbonates & Related Topics, IWMC201 I, held in Paris in 2011 , have put in evidence the importance to improve and exploit this investigation and technological domain."

Jan 1, 2012

By William J. Pardee, Michael A. Shaff

"Deeper materials science knowledge from mathematical models and in situ material property sensors will be exploited in next generation factory process controllers to improve productivity and quality. These intelligent control systems will accelerate productivity growth and materials science application through the ease with which they can be modified to accept new materials knowledge and sensors. Carbonization of resin matrix carbon fiber composites, specifically, is a violent solid state chemical reaction with large stresses due to gas pressure, matrix shrinkage, and differences in thermal expansion. The matrix strength falls sharply, then rises again during the process. At least two competing reaction paths are important; the first cleaves methylene bonds, reduces toughness, density and stiffness; the second reforms those bonds, ultimately resulting in aromatic ring condensation that increases density, strength, and modulus. Since these reactions have different temperature dependencies, one can expect to shift the process towards the second path by changing the heating rate, but that change must be accomplished without producing macroscopic interlaminar crack growth. To accomplish this, we employ gas sensors to infer matrix chemical state and acoustic emission to identify microstructural changes and to recognize brittle fracture. The latter does not prevent delamination, but is important in testing models for the causes of delamination and in improving the processing cycle. This paper describes a control strategy to accelerate the process while still lowering the risk of failure.IntroductionDeeper materials science knowledge from mathematical models and in situ material property sensors will be exploited in next generation factory process controllers to improve productivity and quality. These intelligent control systems will be more easily modified to accept new materials knowledge and sensors, thus accelerating productivity growth. Such a control strategy for carbonization control is described below.Carbon-carbon composites are time consuming and costly to manufacture. Processing methods have been developed empirically and are usually very conservative because the process often fails when any change is made. Apparently minor changes in materials or geometry can produce failures that are difficult to diagnose and correct. We will describe below several essentially unavoidable sources of variability. These are best dealt with by applying materials science to adapt (i.e., closed loop control on materials properties) the process in real time to reduce the effect of unavoidable model idealizations, material variability and environmental noise. The most critical issue in control of the carbonization process control is avoiding catastrophic delamination. The strategy developed below makes use of a priori materials knowledge and real time sensors to accelerate the now very slow process without destroying the material, and without requiring unreasonable resources to determine the statistical properties of the material."

Jan 1, 1988