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By Jie Li, Liangxing Jiang, Yexiang Liu, Junfeng Gui, Bo Hong, Xiaocong Zhong, Yanqing Lai, Xiaoying Yu

"Pb-based alloys with Pr and Ag were prepared in vacuum electromagnetic induction furnace. The tensile strength, corrosion rate and anodic potential in sulfate solution were measured, and the experimental data were analyzed according to the metallographic phases of alloys, the micromorphology and composition of their oxide films. The results show that, with the addition of Pr, the ultimate tensile strength and corrosion rate of pure lead were increased, and the anodic potential decreased. The extra addition of Ag can improve the properties of alloy further. Comparing with Pb-Ag0.8 alloy which is widely used in zinc electrowinning industry, the ultimate tensile strength of Pb-Ag0.6-Pr2.0 alloy was increased by 31.75%, the anodic potential under 50mA/cm2 was decreased by 30m V.IntroductionIn zinc electrowinning industry, the Pb-Ag (0.5-1.0 wt.%, 0.8wt.% normally) anode is widely used as an insoluble anode['l. It can meet the basic requirements, but still has several problems such as high oxygen evolution over-potential (about 860mV), unsatisfactory corrosion resistance, lead contamination of the cathode product and high consumption of Ag etc.In order to reduce the energy consumption, enhance the corrosion resistance, improve the product quality and reduce the consumption of Ag (or even dispense with it), much research has been done, mainly focusing on Pb-based alloy anodes and Ti-based coated anodes. Detailed investigations have already been carried out on binary alloys (Pb-Ca and Pb-Co), ternary alloys (Pb-Ag-Ca, Pb-Ag-Ti, Pb-Ag-Sn, Pb-Sr-Sn, and Pb-Ca-Sn) and quaternary alloys (Pb-Ca-Sr-Ag, Pb-Ca-Ce-Ag, and Pb-Ag-Sn-Co)[Z-4l, Although these anodes can effectively reduce the consumption of Ag, only the Pb-Co and Pb-Ag-Sn-Co anodes perform well with regard to reducing the anodic potential. However, their complicated manufacturing conditions restrict further commercial use.Besides its application in nonferrous metal electro-winning industry, Pb-based alloy is also used as grid alloy for lead-acid battery, serving as active materials supporter and current collector. In order to enhance the corrosion resistance and deep-cycling performance, reduce the impedance of the corrosion film, the addition of appropriate rare earth elements into anodic grid alloys has become a research focus. Studies proved that RE can enhance the mechanical strength of grids, inhibit the formation of anodic Pb(II) film on the surface of grids and then reduce the impedance of the film[ 10-12l."

Jan 1, 2013

By Gaifeng Xue, Lei Zhang, Xia Liu, Lina Wang, Pu Liu, Benquan Fu

"Experiments were conducted to investigate the behavior of the integrated process with a three-dimensional electrode reactor combined with Fenton process for coking wastewater treatment. Effects of initial pH value, reaction time, H20 2 dosage, Fe2+ dosage on Total organic carbon (f OC) removal rate were investigated. The kinetics of degradation of TOC from coking wastewater by three-dimensional fluid bed electrode reactor combined with Fenton process was also studied. Experimental results shows that three-dimensional fluid bed electrode reactor combined with Fenton process had better synergic effect, average 17.4% TOC removal rate was improved within an hour. It was found that TOC degradation in coking wastewater followed a pseudo-first-order reaction kinetic model. The optimum degradation efficiencies of TOC were up to 60% as pH3.4, 3.5 mM ofFe2+ andl.2-1.8ml/L H20 2 in 90min reaction period. Furthermore, the integrated process showed a rapid reaction performance at a low temperature within a short reaction time and remained high efficiencies for TOC removal. Overall, the integrated process was proved feasible for coking wastewater treatment in practical applications.IntroductionCoking wastewater is generated from coal coking, coal gas purification, and by-product recovery processes of coking, which is composed of phenolic compounds, heterocyclic compounds, polycyclic aromatic hydrocarbons, ammonia, cyanide, polycyclic nitrogen-containing aromatics, acyclic compounds, etc. Most of these constituents are refractory, poor biodegradability, toxic and carcinogenic['-31. Currently, coking wastewater is usually treated by different forms of A/O biological nitrogen removal process as the primary treatment process, but the aforementioned processes are not efficient enough to meet the requirements from the National Discharge Standard in China (GB13456-1992). According to the continuous requirement on improving environmental protection for coking industry (revised 2008), increasing wastewater utilization ratio and reducing discharge of effluent in the coke industry has to be implemented for cleaner production and sustainable development. Therefore, advanced technologies need to be developed to treat coking wastewater and reutilize the product as industrial cooling water, which would be one of the best choices to achieve zero discharge of wastewater and reduce water consumption per ton of steel [4-51 . In this study, three-dimensional fluidized bed electrode reactor combined with Fenton process was adopted to advanced treatment of coking wastewater, and the effects of operating conditions, including H2O 2 dosage, Fe2+ dosage, initial pH, and reaction time on TOC removal rate, were investigated. Meantime, study of kinetics of reaction was estimated."

Jan 1, 2013

By Tracey Brommer, Britt Elin Gihleengen, Elsa Olivetti, Randolph Kirchain

"Increased demand resulting from the economic and environmental advantages of recycling secondary materials has constrained secondary material supply. As a result of constrained supply, the conventional strategy to maximize recycled content in an individual aluminum alloy must be expanded to maximizing total recycled content in a given production period. This work compares the performance over a two week period of an actual remelter for two strategies; a sequential charge-by-charge optimization framework and an integrated approach that explicitly incorporates the production schedule. Optimizing across the entire two week production is found to increase recycled content and minimize primary and alloying material additions. It is expected that as the scrap material market continues to be constrained by high demand, longer term batch planning strategies that can optimize material allocation will deliver improved performance.IntroductionIntensifying economic and environmental pressure to incorporate secondary aluminum into products is pushing remelters to explore additional strategies and tools to increase recycled content. Aluminum remelters are exploring alternative sources of secondary materials because of constrained secondary material supply and relatively high primary and secondary material cost [1]. Computational models, such as blending models are a tool that could help industrial remelters mitigate supply and cost challenges and thereby increase recycled content. In particular, computational tools can help manage the incorporation of new raw materials of variable quality. Blending models find many industrial applications and have been explored for over sixty years originating with the classic nut-mix problem dating back to 1950’s [2]. Blending models optimize the raw material input to make a desired product subject to a series of constraints such as product specifications and material availability. Deterministic and linear blending model formulations are presently implemented in some industrial aluminum remelters [3]. The primary reluctance of aluminum remelters against computational model implementation is the incapability of their blending models to reflect the intricacy of industrial remelting conditions [4]. For example, to reduce calculation time, industrial aluminum blending models usually optimize a batch plan for a single alloy and are not formulated to optimize several products simultaneously. Since such a model does not include knowledge of subsequent charges in the optimized batch plan, the resulting batch plans tend to deplete the “cleanest” secondary materials leaving the more uncertain and compositionally challenging materials for later charges. As a result, a remelter may override the calculated batch plan or leave certain scrap materials out of the material input to conserve these materials for alternative products scheduled for later production. This work explores an alternative aluminum charge planning tool that can optimize across an extended production schedule and compares it to a heuristic sequential optimization strategy reflecting an industrial remelter."

Jan 1, 2012

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 Chu Bo-Yi

"This paper contains a comparison of creep-feed and shallow-cut grinding on ceramics with both neat oil and water-based grinding fluids. When a water-based grinding fluid was used in creep-feed grinding on ceramics the vertical forces and specific energies increased markedly fast with result that the wheel surface was damaged seriously. Creep-feed grinding on ceramics with neat oil not only produced much lower grinding forces and specific energies but also resulted in the wheel remaining in good condition and minimizing damage to the ground surface. This finding may lead to a deeper understanding of the behaviors of grinding fluids in grinding processes both on ceramics and metal as well.1. IntroductionAs advanced ceramics are obtaining more and more applications in the technical area, some machining processes are needed after the sintering to reach the accuracy and finish required by components. Because of higher hardness and brittle behaviors of modem ceramic many researches have been done in order to improve grinding efficiency and surface quality.In the grinding metals the concept of creep-feed grinding has been developed in industry as a real alternative to the normal method of shallow-cut grinding. In addition to the general economic advantages, dimensional accuracy and surface integrity are invariable improved using the creep-feed grinding technique.In grinding ceramics former studies have done many works on both creep-feed and shallow-cut grinding on ceramics with water-based grinding fluids since the water-based were thought to be better coolants than neat oil in most tests of grinding metals[l]. It was suggested that the specific grinding energies of ceramics are markedly higher in creep-feed grinding. The grinding force increases vary rapidly with time in the creep-feed case. In other words, so-called speed stroke grinding with high workpiece speed is considered more suitable for improving the grinding efficiency [2][3]."

Jan 1, 1998

By Kerri-Ann Hue, Kerry Hasapidis, Ken Babcock, Patrick O'Hagan

"Metallic nanoparticles exhibit properties that are significantly different from individual atoms or bulk materials. Their applications are diverse and have varying uses in areas such as cancer treatment, biochemical sensors, nanoelectronics, and drug delivery. For each application extensive characterization must be performed in order to probe the unique properties of these nanoparticles. In this study, ultra-high resolution mass sensors consisting of MEMs-fabricated, suspended microchannel resonators (SMRs) were used to determine the size and concentration of metallic nanoparticles. With femtogram (10- 15 g) mass resolution, ultra-high resolution mass sensors can weigh individual particles suspended in fluid, and so measure their mass, density, and size. Particle size analysis with these sensors provides excellent accuracy and resolution compared to mature technologies such as light scattering. This technique also provides quantitative information via the ability count particles.IntroductionThe unique electronic, chemical, and optical properties associated with nanoparticles vary with their size, shape, and composition[ 1-4]. These properties are attributed to increased surface area and nanosized mean free path of electrons to the particle surface. Nanoparticle colloidal solutions have been prepared and are commercially available. In recent years, noble metals such as gold, copper, and silver have been extensively researched[5-7]. In order to tailor the optical, electronic, and electrical properties of nanoparticles, size and shape must be controlled. For many applications a monodisperse colloidal solution is ideal. Methods of size characterization include Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS), and Electrophoretic Mobility Measurements to name a few[6, 8]. Although TEM can provide shape and size distributions, sample preparation requires that samples be dried on a metal grid and cannot be analyzed in solution. DLS uses curve fitting algorithms that while useful for determining mean particle diameters are not ideal for polydisperse colloidal solutions. New technologies are therefore needed to accurately determine the particle size distributions of metallic nanoparticles."

Jan 1, 2011

By Daniel Chen, Jewel Andrew Gomes, Venkata Palla, Sadia Afrin Jame, David Cocke, Paul Bemazzani

"Textile industries use various kinds of chemicals including dyestuffs and pigments during dyeing and finishing processes. The effluent from these processes includes suspended particles, strong color, high pH and high chemical oxygen demand (COD) that are extremely toxic and make environmental hazard. Although physical, chemical, photochemical, and biological methods are available for treating such wastewater, the electrochemical technique, electrocoagulation (EC), has emerged as an efficient, simple, and cost-effective technology in the last few decades. In this study we present the applicability of EC technique for removing dye, such as direct red dye using iron electrodes, and the optimized conditions such as dye concentration, current density and pH. The degradation of dye molecules was investigated using UV-visible spectroscopy. The EC-floe was also characterized using SEM/EDS, XRD and FTIR.IntroductionWastewaters generated by textile industries contain large amounts of toxic aromatic compounds, especially azo dyes. Azo dyes and their degradation products, such as aromatic amines, are highly carcinogenic. These effluents are also responsible for causing high levels of color. The colored wastewater released into the environment is also a source for disruption of aquatic life and aesthetic pollution as well [1].In most textile industries, dyeing and finishing are the two important processes which are generally applied. These two common processes generate significant amount of wastewater, which may contain, suspended particles, high pH, strong color and high chemical oxygen demand (COD) concentration [2]. Low pH and high temperature are other polluting factors from the waste water. Textile industries make use of about 10,000 dyes and pigments [3]. Disposal of these colored wastewaters poses a major problem for the industries as well as a threat to the environment. In textile industries, because of the low efficiency (60-90%) of dye fixing on textile fibers, substantial amounts of unfixed dyes are released in waste waters. The conventional method for treatment of textile wastewater was a combination of biological, physical and chemical methods [2]."

Jan 1, 2011

By S. S. Ryu, J. C. Kim, H. Lee, Y. D. Kim, I. H. Moon

"Recently, W-Cu alloy becomes one of the very important candidate materials for heat sink and packaging in the field of microelectronics due to its good thermal properties. The metal injection molding of W-Cu powder can satisfy the requirement for mass production of complex shaped parts in microelectronic devices. In the present study, the application of MIM process to the nanostructured W-Cu powder prepared by mechanical alloying was investigated. The multi-component binder system of 45PW+ l 5BW+ 30PE+ I OSA was proven to be suitable one for the MIM of the W-Cu composite powders by adopting the debinding cycles of multi-stage in N2 and H2 atmospheres. Other process conditions for the MIM of the nanostructured W-Cu composite powder were also studied. The MIM debinding part of W-30wt.%Cu was sintered to the relative density of more than 96% by sintering at 1200 °C for !hour in H2 atmosphere. Such an improvement of sinterability was attributed to the intrinsic homogenous and fine mixing state of W-Cu phases in nanostructured W-Cu composite powders, and also partly to the effect of the activated sintering by the presence of impurity introduced during the extensive milling.IntroductionW-Cu alloys have been widely used for heavy duty electrical contacts and arcing resistance electrode(1-2). Recently there has been a growing interest in this W-Cu alloy because of its superior thermal managing properties and its high micro wave absorption capacity(3). Such W-Cu alloy parts are conventionally fabricated either by the Cu infiltration sintering technique or by hot pressing of W-Cu powder mixtures. However, these conventional PM techniques are hardly applicable for mass production of small size parts with a complicated shape such as the parts required for microelectronic devices. The metal injection molding(MIM) technique is potentially applicable for the mass production of small and complicatedly shaped parts compared with other PIM forming techniques."

Jan 1, 1998

By John P. Hager

One possible approach for the recovery of mercury from acid plant blow-down sludge in smelters is the use of a vacuum retort reactor for the vaporization of the mercury with subsequent collection of metallic mercury in an attached condenser. An experimental study was undertaken to investigate the vaporization of mercury when present as a compound in the Hg-S-O and Hg-Se systems. A transpiration reactor was modified to operate under reduced pressure and with a continuous flow of inert sweep gas. A water-cooled cold finger was inserted into the exit end of the reactor to provide for the rapid quenching of the exit gases and the collection of the mercury. Rates of vaporization were measured at several temperatures for each compound and were generally found to be constant at a given temperature and reactor pressure. The results were used to determine the minimum operating temperature for 100% vaporization of the compound in 60 minutes. For Hg2SO4, HgSO4, and HgSO/2HgO the required temperatures. for a reactor pressure of 50 Torr. were determined to be 634°, 622°. and 603°C. respectively. For HgO, HgSe, and HgS the required temperatures were 557°. 451°. And 382°C. respectively. For HgS the rate of vaporization was also measured at a reactor pressure of 1 00 Torr. The rate of vaporization was found to be slower resulting in an increased vaporization temperature of 423°C. It was also determined that the mercury vapor present in the exit gas stream can back-react with the other gas species to a significant extent and can result in very little condensed metallic mercury. For the vaporization of both HgS and HgSe. the mercury vapor was found to have back-reacted to the extent that virtually none of the vaporized mercury was collected in metallic form. For the vaporization of Hg2S04? HgS04, and HgSO4*2HgO the amount of metallic mercury recovered varied from approximately 50% for HgS04*2HgO to approximately 10% for Hg2S04 and HgS04. Only for HgO was the recovered mercury in primarily elemental form. The application of the results to the operation of a vacuum retort and condenser system is discussed.

Jan 1, 2001

By S. Mattlgod

Self-assembled monolayers on mesoporous supports (SAMMS) have been developed for the removal of heavy metals and some transition metals. The thiol functional groups were assembled on the internal and external surfaces of mesoporous silica with a uniform pore size of about 55 A. The mesoporous supports provide high surface area (>900 m2/g) needed for high metal loading in chemical separation. Self-assembled monolayers of organic molecules bond to the ceramic substrate with prescribed densities, and with terminal functional groups for excellent molecular selectivity. The unique characteristics include: (1) High metal absorption capacity, up to 3.2 mmol/g of SAMMS. (2) Fast Hg-binding kinetics (reducing mercury concentration from 0.5 ppm to 0.5 ppb in less than 5 minutes). (3) High selectivity in the presence of a range of cations, anions, and organic species. (4) Applicability in both aqueous and non-aqueous solvents. (5) Flexibility in surface chemistry. The materials can be designed to adsorb heavy metals, transitional metals, and radionuclides. (6) Chemical stability, and potential for regeneration or waste storage. This paper discusses the results on mercury adsorption.

Jan 1, 1999

By Kee Jeung Lee

In this study the characteristic factors and formation mechanisms for the hydrothermal preparation of a -quartz crystal powders were investigated to find the optimum synthetic conditions. The degree of Q -quartz crystal face development depended on the relative growth rate of a particular form that varies considerably with the degree of supersaturation, the reaction temperature, the concentration of mineralizers, and the presence of seed crystals in the feedstock. Alkali hydroxides and alkali halides were found to be effective in the reactions as mineralizers, which added in order to increase the solubility of the feedstock. The fine Q -quartz crystal powders were obtained in the temperature range of 250-450% and pressure range of 100-300atm. As the concentration of mineralizers increased, the particle size of crystalline powders became smaller at lower reaction temperatures. The fractional size distribution of synthetic crystal powders was depended on the hydrothermal conditions. As the reaction time and the amount of seed crystals increased, the width of particle size distribution became narrower. The weight mean particle size was in the range of 1 to 10m. The characterization of the products were carried out using XRD. SEM. PSA, FT-IR, Raman spectrometer.

Jan 1, 1997

By E. Allaine

Carbochlorination kinetics of pure MoO3, Nb2O5, Ta2O5 and V2O5, by Cl2+CO+N2 gas mixtures was investigated between 380 and 1000 °C. Standard free energy of carhochlorination reactions and phase stability diagrams of these refractory metal compounds were calculated. The influence of total gas flow rate, temperature, reactants partial pressures on the reactivity of these oxides were investigated. The apparent activation energies were found to be about 83, 75, 110 and 100 kJ/mole below 650°C for MoO3, Nb2O5, Ta2O5 and V2O5, respectively. Above this temperature, the Arrhenius plots exhibit a rate anomaly attributed to thermal decomposition of COCl2 and/or structural changes of these refractory metal oxides. The apparent reaction order of carbochlorination of these oxides with respect to Cl2+CO was determined. For these refractory metal oxides, the reaction rate was maximum for a Cl2/CO ratio of about 1 in the chlorinating gas mixture. Results of carbochlorination of these oxides are compared and discussed.

Jan 1, 1995

By C. García

Several modifications to Zaldivar's original design have been made in order to reach the design cathode production. This paper describes the modifications to the crushing, leaching, solvent extraction and electrowinning operations, which in turn have increased the production by 14.8% over the design capacity in 1999. The principal modifications were to (1) incorporate a dry pre- screening plant between the secondary and tertiary crushers to increase the percentage of fines to the piles, (2) increase the retention time of the solutions inside of the piles, and (3) increase the efficiency of the tertiary crushers to reduce the particle size of the product material. The leaching ratio was increased from 2.8 to 5.6 m3/ton. The temperature of the pregnant leach solution (PLS) was increased, the amount of acid used was reduced, and a strain of native bacteria was adapted in highly contaminated solutions. The copper concentration in the PLS was increased by more than 50% and was stabilized at this level by commissioning a process of two-stage leaching. The current density in the tankhouse was increased from an average of 2 16 to 3 17 A/m

Jan 1, 1999

By Hidekazu Nakagawa

We investigated the anodic dissolution behavior of titanium in TMHA-Tf2N molten salt, which has a wide electrochemical window of about 5 V, in order to develop an electrodeposition method for titanium. By etching a titanium electrode in HF?HNO3?H3PO4 solution, the titanium electrode became electrochemically active, and a redox reaction was observed at around -0.15 V vs. I-/I3- in (TMHA-Tf2N)?HTf2N solution. We identified the redox reaction consists of the reduction of the proton and the oxidation of hydrogen. The diffusion coefficient of the proton in TMHA-Tf2N was calculated to be 6.9 10-8 cm2 s-1 at 50 °C from the cathodic peak current in the cyclic voltammogram. Anodic decomposition of the molten salt was not observed up to 6.0 V vs. I-/I3- on titanium electrode, while it was observed at around 2.0 V vs. I-/I3- on platinum and glassy carbon electrodes. Cathodic decomposition of the molten salt was observed at around -3.0 V on the titanium electrode, as well as on the platinum and glassy carbon electrode.

Jan 1, 2006

By K. Koike, N. Masuko, Y. Takasaki

At the Zinc & Lead'95 symposium, one of the authors presented several modifications of Pb-Ag-Ca alloy anodes for the zinc electrowinning process, and also, the behavior of some organic additives in the electrolyte. In this study, the mechanical properties of the electrode materials composed by Pb-0.5 wt% Ag-(0~0.8) wt% Ca were studied by the tensile and Vickers hardness methods. Furthermore, experimental research on the influence of rolling and annealing treatments on the electrolytic behavior and mechanical properties of these alloys was carried out. The tensile strengths of the annealed Pb-0.5 wt% Ag-(0.1-0.8) wt% Ca alloys were the same or higher than those of the as-cast Pb-0.9 wt% Ag alloy. The anode potential using the as-cast Pb-0.5 wt% Ag-0.6 wt% Ca alloy decreased compared to the as-cast Pb-0.9 wt% Ag alloy. Moreover, the annealed Pb-0.5 wt% Ag - 0.6 wt% Ca anode after rolling showed a lower anode potential than the as-cast Pb-0.5 wt% Ag - 0.6 wt% Ca anode.

Jan 1, 2000

By J. Antonio Barrera-Godinez, S. E. James, J. Sun

The solvent extraction separation of iron from a zinc sulfate medium using DEHPA was investigated. After loading, the ferric ions were reduced in the organic phase using metallic zinc. The ferrous ions produced could be easily stripped into a sulfate solution with pH values in the range of 1.4 to 2.0. The small, laboratory scale pilot system used in this study allowed for continuous cycling of the organic and strip aqueous solutions. It was possible to establish and evaluate a series of steady state conditions under selected operating paiameters. The effects of processing parameters such as solution chemistry, flow rates, zinc metal loading and pH on iron recovery and efficiency were also evaluated. Under proper conditions, it was possible to remove about 5 g/L iron from the organic phase in one stage and to produce a concentrated iron sulfate strip solution containing ferrous ion concentrations in the range of 90 to 130 g/L. Preliminary feasibility tests were also made on electrowinning metallic iron from the strip solutions and crystallizing ferrous sulfate as a means of making a marketable iron product.

Jan 1, 2000

By Admire Chaendera

A gas jet was blown through submerged nozzles to stir the bath in the presence and absence of slag. Mixing and mass transfer rates were then studied. Water and kerosene (10% by volume) were used to simulate the metal and slag phases respectively in the cold model. The mixing time (Tmix), defined at 99.66% bath homogeneity level, increased with bath height and decreased with an increase in the gas injection rate. Its value in the model vessel was related to gas flow rate (Q), bath weight (W), and bath height (H) by, Tmix = 4.39Q-0.73W0.24H1.12. Inclusion of the slag phase increased Tmix by about 16% and the mass transfer parameter, [(Reloc,r)0.25(Ret)0.32], values by about 32%. Mass transfer rates were higher near the bath surface and in the gas-liquid plume region. They increased with gas flow rate but decreased with an increase in bath height. The relationship, K Q0.08, showing derived mass transfer coefficient (K) dependence on the gas injection rate (Q) was established. The proportionality constant in the equation varied with gas flow rate and sample location.

Jan 1, 2006

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 2:1. The samples having the density more than 99% of the theoretieal 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 casting 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 Toshiaki Nakai, Kunihiko Takeda, Kimio Imaizumi, Hiroaki Shirasaka

"The new type of nano-porous silica particle was considered to be constructed by the spinodal decomposition-type process which was found to have narrower pores than those of conventional porous silica prepared from boron silicate or ""Shirasu"" balloon. Nano-porous silica particles were fabricated by the calcination of silica gel mixed with well-dispersed complex salts composed of phosphorous and molybdenum compounds. Both silica and inorganic salts were not perfectly dissolved in the suspension solution. After removing of the water, the silica-inorganic salts complex was volatized and successively calcinated at a temperature ranging from 650 °C to 800 °C. Then, the inorganic salts were removed by dissolving in hot water. Other inorganic salts such as potassium halides were also found to be effective as a pore-size controller.IntroductionControl of structure has an important role in the field of industry as well as in the separation and purification technology for metals and organic syntheses. Many studies on the control of material structures have been reported regarding porous materials with pores ranging from nanometer to micrometer scale. 1 ) One example is zeolite as a naturally yielded porous inorganic material. Various types of synthetic zeolites have been studied as ""molecular sieve"" materials with ordinary pore-size of less than one nanometer. In 1992, crystalline meso-porous material with a large surface area named MCM-41 was synthesized through the use of template synthesis. 2) In direct relation to our study, amorphous borate glass having 4 to 100 nm of fine pores known as Corning glass 3l or SiO2-Al2OrB2O 3-CaO porous glass having large pore dispersity ranging from 4 to 10,000 nm have been reported. 4 ) S) 6 ) Some examples of several reported studies are as follows: phase-separated porous glass consisting of B2OrAl2O3-ZrO2-RO-R2O complex oxide 7 ) glass with finer pore induced from hydrolysis of silane alkoxide, porous material attained by condensation polymerization through the use of sol-gel process 8), alumina meso-porous material 9 ) 10), silica-zirconia material 11), carbon porous material 12), etc.."

Jan 1, 2000

By Klaus-Markus Peters, Robert M. Cravens, James G. Hemrick

"Degradation of refractories in molten aluminum applications leads to energy inefficiencies, both in terms of increased energy consumption during use as well as due to frequent and premature production shutdowns. Therefore, the ability to enhance and extend the performance of refractory systems will improve the energy efficiency through out the service life. TCON_ ceramic composite materials are being produced via a collaboration between Fireline TCON, Inc. and Rex Materials Group. These materials were found to be extremely resistant to erosion and corrosion by molten aluminum alloys during an evaluation funded by the U.S. Department of Energy and it was concluded that they positively impact the performance of refractory systems. These findings were subsequently verified by field tests. Data will be presented on how TCON shapes are used to significantly improve the thermal management of molten aluminum contact applications and extend the performance of such refractory systems.IntroductionThe production of molten aluminum creates aggressive environments for processing equipment, thereby requiring refractory materials to contain the aluminum during melting, transfer, treatment, and casting operations. Degradation of these refractories not only causes issues with reduced product quality and production yields, but also increases heat losses as the insulative properties of the refractories are compromised. Furthermore, in addition to disrupting production output, refractory failures lead to further impacts upon energy efficiency as large amounts of energy are lost during the cooling and subsequent reheating of the equipment as the refractory linings are repaired or replaced.The need for improved refractory materials is recognized throughout the industry. A joint U.S. Department of Energy and industrial workshop held in 2000 on applications for advanced ceramics in aluminum production [1] noted that refractory materials used in melt processing equipment have many limitations. The workshop report noted that these issues may be addressed by using advanced ceramics, but new materials must be cost effective when compared to current refractory materials. Also, in 2005 the Canadian aluminum industry produced a technology roadmap [2] having the goal of identifying and bridging gaps between current technological resources in the industry and future requirements. One of the areas identified as being crucial to the future of the industry was the need for improved molten aluminum-resistant materials."

Jan 1, 2009