Search Documents

By Kimio Itagaki

Thermodynamics and rate process fundamentals are two of the important principles involved in nonferrous production processes. The process configuration establishes whether thermodynamics or rate process behavior is most relevant in a particular application. In this paper, thermodynamic theory and rate process fundamentals are used to analyze the main characteristics of smelting and converting processes. The effect of increased oxygen potential .is examined with emphasis in view of the increased use of highly oxygen-enriched gas in modem smelting processes. Phase equilibrium and the distribution of minor elements between copper or nickel matte and FeOx-SO2- or FeOx-CaO-based slag are reviewed. The use of oxygen-rich gas has no serious effects on 'the recovery of valuable copper and silver in the matte phase, while the recovery of nickel and cobalt is adversely affected. The oxygen content in the gas also strongly affects the distribution behavior of arsenic, antimony and bismuth. Analysis of the rate processes occurring in the shaft of flash smelting, and converting furnaces by a 3-D computational fluid-dynamics model is also discussed. After being validated with experimental data collected in a large laboratory furnace, the computer model has been used to simulate the main features of an industrial flash converting operation. The results present quantitative features of the improved mixing of the particle-gas suspension and increased oxygen efficiency obtained with a distributor-cone burner compared with those with a single axial entry burner. The role of basic principles in the engineering analysis of high-intensity matte smelting processes is also discussed.

Jan 1, 2002

By Peng Peng, Ouo Cheng, Guodong Lai, Lijuan Chu, Zebiao Zhang

"The pressure acid leaching residue of zinc concentrate contains a large quantity of sulfur. The present study attempts to leach sulfur using a mixture of ammonium sulfide and water solution at 25°C. Effects of three leaching variables: ammonium sulfide concentration, leaching time, liquid/solid ratio on the sulfur leaching rate were investigated. The process conditions were optimized using response surface methodology based on the central composite design. From the analysis of variance (ANOVA), the significant factors on response were identified. The optimum conditions for leaching elemental sulfur from pressure acid leaching residue of zinc concentrate were obtained using an ammonium sulfide concentration of 2.5 mol/L, leaching liquid-solid ratio of 6.5:1 and leaching time of 7 min. Under the optimum experimental conditions, a maximum of 98.50% of total sulfur was extracted. The experimental results obtained agreed satisfactorily with the model predictions, with a correlation coefficient (R2) of 0.99.IntroductionSulfur is widely used in agriculture, medicine, rubber, building materials, gunpowder, wine and sugar, and other fields [1]. Currently the world sulfur production is 40Mt, out of which more than 90% is recovered from industrial processes, and 10% is natural [2], This highlights the importance of sulfur recovery. As the pressure leaching technologies [3] continue to mature and are increasingly applied to refining, a large quantity of high-sulfur residue is produced [4-5]. It is desirable to recover sulfur from this residue, so that it is economically advantageous, and reduces environmental pollution [6]."

Jan 1, 2012

By V. Bojarevics, K. Pericleous

"A number of different methods have been developed for noncontact electromagnetic treatment of liquid metal and to investigate the melting/solidification processes. Applying AC magnetic field in terrestrial conditions, along with the buoyancy and thermo-capillary forces, results in turbulent flow. The use of a homogenous DC magnetic field allows damping both of the turbulence and the large scale flow at different rates leading to surprising results at some stages. The dynamic interaction of the turbulent flow with the oscillating interface needs to be accounted if it is required to levitate liquid metal of up to few kilograms without the contact to container walls. At the high values of magnetic field some oscillation modes are damped quickly, while others are modified with a considerable shift of the oscillating droplet frequencies and the damping constants from the non-magnetic case. Numerical models are used to investigate behavior of liquid metal suspended in high DC magnetic fields providing microgravity-like conditions with laminar viscosity and heat transfer to the surroundings.IntroductionSince the early Electro Magnetic (EM) levitation experiments [1] in AC magnetic field it became apparent that the levitated liquid metal is prone to oscillation and instability. The EM and electrostatic levitation experiments with liquid metal droplets show difficulties related to confinement stability and a need for complex correction functions to establish a correlation between the measurements and the droplet material properties [2,3]. Intense internal fluid flow is visually observed, apparently being in the turbulent regime for earthbound conditions."

Jan 1, 2012

By Raj Mutharasan

The phenomena of gas-molten metal reactions for the production of metal matrix composites consist typically of a combination of one or more gas transport steps and a liquid gas reaction step. Reaction products include such strength enhancers, grain refiners, or high thermal conductivity phases as TiC, AIN, SIC, Si3N4, TiN in aluminum alloys. Nitrides, carbides and oxides can be produced at various volume fractions and in fairly fine sizes (500 am to 5 um) in laboratory melts by Reactive Gas Injection method (RGI). Gas injection methodology to produce the reinforcements is attractive because it can potentially be scaled to production scales in excess of 10,000 kg/h. For continuous production, the reactant molten metal can be continuously fed into the .crucible where the reactive gas is injected. The molten metal phase reactant may also be involved in a controlling transport step, depending on its concentration and viscosity. It is well known that the reaction product reinforcement size and shape of these phases have significant impact on the physical, mechanical and thermal properties. The current state of knowledge is unable to predict the kinetics and growth of solid reaction products obtained. The primary goal is to develop a fundamental framework for the understanding and prediction of the particle size in such reaction systems. In addition, the role of gas transport, liquid hydrodynamics and decomposition are important issues. A reaction-transport model is being developed using a reaction, transport, and thermodynamic framework, both at macro and at atomistic level to assess gas - liquid interactions.

Jan 1, 1996

By Shichao Zhao, Ke Xie, Qijie Zhai, Wenbin Xia, Yuanyi Guo, Changjiang Song

"This paper investigated the structure evolution and phase formation ofFe-(11,13,15wt.%)Mn alloy under near-rapid solidification conditions. It is found that the area ratio of equiaxed zone in the Fe-13Mn alloy is the largest. And the primary dendrite arm spacing of Fe-(11,13,15wt.%)Mn alloy increased clearly with increasing distance from the surface. The volume percentage of HCP phase increased with increasing manganese content in the range from 11 pct to 15pct.IntroductionThe developing trend of automobile is the energy conservation, enviromnent protection, light weight, and high security. So the material would be required to the higher strength, higher plasticity and more likely to processing of automotive steel. Fe-Mn based alloys is considered as a potential material to the third generation automobile steel for its high damping performance [1], good mechanical properties [2-3], and high young's modulus [4]. And it is important that metastable HCP phases of Fe-Mn based alloys, which attracts technological interest for theoretical and experimental research [5-6].Metastable materials have been extensively used in the area of iron steels. Among various fabrication methods for high performance materials, rapid solidification is one of most popular ways to produce advanced materials by obtaining metastable phases. The solidification of metals in metastable phases provides access to an extended range of materials properties with novel properties [7]. Thus, in this work, Fe-Mn alloy metastable materials prepared by near rapid solidification is studied."

Jan 1, 2013

By Yue Gong, ChuanJie Cai, Jing Chen, Shaobo Zheng, Huigai Li

"MnS-AlN duplex precipitates were successfully extracted from electrical steel slabs by means of non-aqueous solution electrolysis. The three-dimensional duplex morphology became visible using emission scanning electron microscope (SEM) JSM-6700F and energy dispersive spectroscopy (EDS). The precipitation sequence of MnS and AlN in the hot process can be predicted via the three-dimensional duplex morphology. Thermodynamic calculations were carried out on account of the chemical compositions of the steel studied in this paper. The results verified that AlN nucleated on MnS, which precipitated earlier during cooling process of electrical steel. Based on the results, the material compositions and rolling temperature can be adjusted to modify their precipitation timing and morphology. This is conducive to the growth of MnS-AlN duplex precipitates and reducing the obstacles to grain growth. Finally the magnetic property of electrical steel would be improved.IntroductionElectrical steel is a kind of ferrosilicon soft magnetic alloys with extremely low carbon content. It is mainly used in the manufacture of motors, generators, transformers and varieties of teleco=unications equipment. Non-oriented electrical steel requires isotropic high magnetic induction and low iron loss [l, 2]. Precipitates in steel have a great influence on its performance [3]. On the one hand, the indirect effect of precipitates on magnetic properties is to restrict grain growth in high temperature annealing process. On the other hand, the direct effect is pinning of domain wall motion, which leads to increased hysteresis loss."

Jan 1, 2013

By Boris Arlyuk

The system of short term forecast of metal prices at LME is based on correlation between prices within the quarter forward and at the first place by economic parameters at the West, determining the consumption of metals. Such economic parameters are presented by data of indexes of Western World industrial production (WW IP), official data of IP and Dow Jones indexes at USA. For price forecast within the quarter forward (one day ahead, 3 day -65 days MA forward prices) are significant the changes of actual prices (official and close) at the past and the parameters of daily trade at LME at the past (futures turnover, open interest, LME stocks). It is developed subsystem of price forecast within the quarter forward based on analytical approach determining the relations between the participants of the market. It gives the opportunity to reduce the number of empirical coefficients at the model and receive good accuracy of forecast the MA prices and its direction at the future. Very important part of short term forecast is subsystem determining analytically the probability that the price forecasted for the next trading day will be the maximum or minimum daily price within the quarter forward. The thresholds probabilities are defined by identification the model at the past by maximal commercial efficiency. Such system was tested at the past at period since 2000 till 2005 and gives very high commercial results at operations on 1M forwards and hedging the sales of nonferrous metals traded at LME (primary aluminium, light alloys, nickel, copper, zinc, lead and tin).

Jan 1, 2006

By Thomas K. Chow

For the well-being of all living creatures and in response to green-environment policy from governments around the global, it is essential to reduce SO2 emissions from mining / smelters as well as other industrial facilities around the globe. However, often times, these SO2 containing flue gases and smelter flash gases also include oxygen and SO3, which complicate the SO2 removal process and technology. There are many novel technologies recently developed for removing SO2 from such gases. Most of these, however, have not yet commercially demonstrated that they are technically viable and economically feasible. Many of these novel processes also generate undesired byproducts, which themselves then need to be disposed of in a safe and cost effective manner. Fluor has developed the Fluor SOx Cleanup Process with a wide variety of process configurations to customize removal of the undesired flue gas constituents in a cost-effective manner. The process removes practically all SO2 in the form of salable elemental sulfur and also reduces CO emissions. Successful operation of major components of the Fluor SOx removal technologies has been demonstrated in many commercially operating units. Besides their technical viability and economic feasibility, Fluor SOx removal technologies do not generate any undesired byproducts or encounter SO2 associated corrosion issues. Moreover, these technologies produce high-purity, saleable elemental sulfur. This paper discusses the merits of the Fluor SOx removal technologies, their technical and cost advantages, their simplicity in design and operation, and their readiness for implementation.

Jan 1, 2006

By C. Zografidis, K. Karalis, E. Devlin, S. Tabouris

"The main parameters affecting energy and electrode consumption in smelting reduction of Greek nickeliferous laterites in submerged arc electric furnaces (E/F) were investigated. Within this framework, the operational data of E/Fs, such as energy consumption indicators, electrode consumption indicators and chemical characteristics of Fe-Ni and slag, were correlated with the physicochemical characteristics of the calcine, produced by roasting reduction of laterite in rotary kilns (R/Ks), such as reduction degree, temperature, chemical composition and granulometry. The results obtained provide a significant input for further research on the modelling of the roasting reduction – smelting reduction process, which is a critical tool for energy optimization.IntroductionThe two main steps of pyrometallurgical treatment of greek nickeliferous laterites for ferronickel production include: i) drying, pre-heating and controlled pre–reduction of laterite ores with solid fuel reducing agents and fuel oil in rotary kilns (R/Ks) for the production of a calcine, and ii) smelting reduction of the calcine in open-bath submerged-arc electric furnaces (E/Fs) for the production of Fe-Ni alloy with 12-16% Ni [1].The energy absorbed from the endothermic reductive reactions of iron, nickel and cobalt oxides (Fe2O3, FeO, NiO and CoO) of the calcine with the remaining carbon in the E/Fs, corresponds to about 16% of the total energy output in the smelting reduction step [1]. This is indicative of the significance of the calcine’s reduction degree for the electric energy requirements in the E/Fs. Moreover, the chemical characteristics and the granulometry of the calcine constitute critical parameters for the energy requirements as well as the smooth operation of the E/Fs."

Jan 1, 2012

By Dai Xi

In the present work, the viscosities of molten FenO-MgO-Si02 and FenO-MgO-CaO-Si02 semi-synthetic slags for nickel flash smelting were measured in the temperature range from 1473 to 1723K by a rotational viscometer. The ratio of Fe to Si02 was fixed at 1.2, calcium and magnesium oxide contents varied in the range from 2 to 8 mass% and 9 to 12 mass%, respectively. The results showed that silicate anions became smaller by increasing CaO content, which results in a decrease of the viscosity of the slag. In the case of MgO addition the viscosity behavior was complicated. At MgO content below 11 mass%, the viscosity increased with the increase of MgO at all temperatures tested. However, when the MgO content was above II mass%, the viscosity decreased slightly for FenO-MgO-CaO-Si02 system. At higher MgO contents, low-viscosity slags can be obtained by adding CaO. At a given composition, the viscosity decreased with increasing temperature. The higher the temperature, the more MgO can be added before saturation. The effect of Fe304 on the viscosity was quite significant. The viscosity of slag increased by 300mPa's at l573K when Fe304 content varied from 3 to 9 mass%. The viscosity values are presented as the functions of temperature and composition. A comparison between FenO-MgO-Si02 and FenO-MgO-CaO-Si02 systems is given in this study.

Jan 1, 2003

By Binxu Zeng, Mark Jolly, Xiaojun Dai

"The traditional investment casting foundries use batch melting and chunky running systems to produce casting components. This method leaves the energy saving issue as subsidiary one. In our research project, one of the partners, the AEROMET international PLC provides the thin wall aluminium component ""filter housing"" for test. The AERO MET uses traditional casting route to produce the filter housing, which only gives 5% --10% yield. In this paper, numerical simulation method is used to analyse filling and solidification of the casting running system. The CRIMSON running system of the filter housing is designed by using casting simulation software, MAGMAS and Flow3D. By working with AEROMET, various configurations of the casting running systems were tested and analysed. Using them ultiple life cycle approach, the energy content of new process is compared with traditional one. It indicates that the CRIMSON process only uses 36% of energy consumed by the traditional route.IntroductionThe investrnent casting is a metal for ming process using expendable patterns, which is a standard casting technique and is widely used to produce quality parts. Its accuracy, versatility and integrity tie itself to important and precious engineering components in Aerospace industry. However, traditional investrnent casting process usually uses chunky runner system and gravity filling method. It not only reduces the casting yield of the product but also causes the pouring defect during the casting. As author's previous research showed that gravity filling method pouring basin and down sprue are two main resources of entraimnent defects generation. No matter how good the running system is, entraimnent defects such as double oxide films (DOF) and bubbles will I get into the casting to cause problem."

Jan 1, 2013

By Masahiro Sasaki, Wu Kepeng, Chang-Yong. Kang, Kohji Okada, Naohiro Igata, Kazuya Miyahara

"The damping capacity of the Fe-12 mass % Cr-6 to 30 mass % Mn alloys has been investigated. Particularly the effects of microstrucutre composed of the phases of a , a ' , y , and e on the damping capacity have been clarified. Various fraction of these phases were formed depending on the Mn content and cold work degree. The combination of 22 mass % Mn and 50% cold rolling formed the largest volume fraction of e martensite and showed the highest damping capacity. The other phases of a, a' and y had very small effect on the increasing of damping capacity.IntroductionFe-Mn alloys are known to be one of the high damping capacity materials [l-3]. In the present research, the damping capacity of the Fe-12 mass % Cr-6 to 30 mass % Mn alloys, in which 12% Cr is added for the improvement of corrosion resistance of the Fe-Mn alloys, has been investigated. Particularly the effects of microstrucutre composed of various phases of a (bee), a ' (bet martensite), y (fee), and e (hcp martensite) on the damping capacity have been clarified. The results of preliminary research on Fe-Cr-Mn alloys are reported by Igata et al. [4] Various volume fraction of these phases were formed depending on the Mn content and cold work degree. The combination of 22 % Mn and 50% cold rolling formed the largest fraction of e martensite and the measurement indicated clearly that e martensite had the largest effect on the damping capacity. The other phases of a ' y and a I had very small effect on the increasing of damping capacity."

Jan 1, 2000

By Ulrich E. Klotz, Gemot Pottlacher, Shahid Mehmood

"Platinum alloys are frequently used in technical applications and in jewellery. Their thermophysical properties such as density, heat capacity, thermal conductivity and surface tension play an important role in casting processes and are required as input data for casting simulation. Scope of this work was to investigate these properties by different methods. Platinum and four alloys namely, Pt96Cu4, Pt68Cu32, Pt50Cu50 and Pt25Cu75 were investigated. Melting range and thermal expansion was measured at fem by DSC and dilatometry, respectively.At TU Graz wire shaped samples were investigated by an ohmic pulse heating technique. This technique allows the calculation of specific heat capacity and the temperature dependencies of electrical resistivity, enthalpy, and density of these alloys in the solid and liquid phase. Experimental results were compared with available literature and data from thermodynamic calculation using the SNOBl database and ThermoCalc.IntroductionPlatinum is a precious element and its alloys are commonly used in jewellery. But Platinum is much more difficult to cast then other jewellery elements like silver or gold, because of its high melting temperature, large shrinkage during freezing, low thermal conductivity, high surface tension, and high viscosity. As a result there arise problems during casting. Hence to resolve these difficulties a detailed study of thermophysical properties of solid and liquid platinum and its alloys is necessary for simulation and casting. The Platinum alloy samples were prepared by vacuum induction melting and casting into copper molds. Rods of 3 mm in diameter and a length of 80 mm were prepared and drawn to wires of 0.5 mm in diameter."

Jan 1, 2011

By Kazuyuki Kakegawa

"Sintered body of lead zirconate titanate (PZT) was prepared through the spark plasma sintering (SPS) technique. When the mixture of raw materials was calcined at 800°C and sintered at 900°C for 10 min. with SPS technique, the sintered body had almost theoretical density but was a mixture of lead titanate (PT) and PZT. When a calcining temperature of 1100°C was employed, sintered body had a single PZT phase but a lower density. High dielectric constant was obtained for a sample calcined at 800°C, sintered with SPS tecbriique and fired again in the air at 1100°C.IntroductionSpark plasma sintering (SPS) is a recently developed technique for sintering metals and ceramics1. The scheme of SPS is shown in Fig. 1. Sample is put in a graphite die in a vacuum chamber. It is pressed and pulse voltage is applied. The electric current heats the die. It is said that the pulse causes a spark-plasma between particles in the sample. Because of the spark- plasma, sample can be sintered at temperatures lower than that in the ordinary sintering by several hundred degrees of Celsius. The sintering period is also very short2Low sintering temperature and short sintering period in SPS technique cause low reaction rate. It is both disadvantage and advantage. In some cases, the reaction cannot be completed under the SPS conditions. If a mixture of several compositions having different properties can be sintered without a compositional change by the diffusion during the sintering, combination of properties, and therefore a design of property will be possible3. The low reaction rate of SPS may enable such combination."

Jan 1, 2000

By Z. Zak Fang, P. Fan, S. Middlemas

"Titanium dioxide (T1O2) has been widely used as pigment in paints, paper and cosmetic products, as well as high-tech applications such as PV Cells, semiconductors, biomedical devices and air purification. T1O2 pigment is primarily produced by the high temperature chloride process, resulting in considerable CO2 emissions. A novel hydrometallurgical process for making T1O2 pigment without direct CO2 emission is investigated. The new method promises to eliminate direct CO2 emissions, consume significantly less energy, and produce minimal environmental waste. The novel process involves molten salt roasting of titania slag, with subsequent washing, leaching, solution purification, hydrolysis, calcination and post-treatment stages, resulting in high-purity anatase or rutile pigments while realizing significantly reduced environmental impacts. Pigment whiteness is critically sensitive to trace amounts of discoloring impurities such as iron and chromium. Several methods for reducing the levels of these impurities are investigated. Energy consumption and emission models are also developed.IntroductionTitanium dioxide (T1O2) is one of the most commonly used minerals in the chemical manufacturing industry. It has been commercially processed since the early 1900's, and has a wide variety of applications. Pigment is used in paints [1], plastics and paper [2], sunscreen [3], cosmetics and even as a food additive [4]. T1O2 has also been used in photovoltaic cells [5], biomedical devices [6], and in air purification [7]. T1O2 pigment has a refractive index of 2.7, which imparts a high level of opacity (and hence whiteness) to whatever material it is added [8]."

Jan 1, 2012

By J. H. Huang

In this investigation, the selective precipitation of cobalt and molybdenum from Co-Mo aqueous solutions was studied in order to recover efficiently valuable elements from industrial effluents generated from a novel electrodeposition of nanocrystalline Co-based alloys process and reduce the effluent impact on environment. It was found that the behavior of cobalt in aqueous solutions was substantially affected by the presence of molybdenum. When adding 11.6 to 46.6g/L molybdenum to a 50g/L cobalt solution, the co-precipitation of molybdenum and cobalt started to occur at pH value of 3-4. However, without the presence of molybdenum, cobalt could only be precipitated out of the solution at about pH 6. Most of the molybdenum was found in the solid phase when the solution pH reached 5. After further increasing pH to greater than 7, the molybdenum dissolved back into the solution. Cobalt kept precipitating as the pH increased. When the pH was greater than 7, most of the cobalt was present in the solid phase. The chemical and physical characteristics of the precipitated materials were investigated by SEM, XRD, AAS and EDX. It was revealed that the precipitate was initially present as cobalt molybdate oxide hydrate and subsequently transformed as sodium cobalt molybdenum oxide. With further increasing the solution pH, the precipitate was transformed into cobalt hydroxide. Further investigation implied that most of molybdenum was chemically tied to the precipitate produced at the low pH, yet at the same time, physically entrapped at the high pH. The paper also presents the influence of reaction temperature and time on the precipitation process and kinetics.

Jan 1, 2003

By Guojun Ma

The entrainment of charge materials, evaporation or volatilization of elements and ejection of slag and metal by spitting or the bursting of gas bubbles are mechanisms whereby stainless steel plant dust are generated from the electric arc furnace and refining converter. TCLP and ASTM D 3987-85 tests on dust that was collected from the baghouse filter system of a South African Stainless Steel plant showed that this dust can be considered hazardous according to South African legislation, due to the high degree of Cr (VI) leachability (~13mg/l for TCLP and ~8mg/l for ASTM vs. regulation threshold of 0.05mg/l in drinking water). The dust is therefore considered to be harmful to both the environment and human health, due to its high solubility in water and carcinogenic properties. It should therefore be treated before being stockpiled or land filled. This paper consequently describes an investigation into the formation of Cr(VI)-containing stainless steel plant dust and the stabilisation thereof in a sintering process, whereby the dust was mixed with a silica-rich clay. It is postulated that Cr(VI) form when the (Mg,Fe,Mn,Cr)3O4spinel phase, CaO, Ca(OH)2 and CaF2 (all of which are present in the dust) react. This reaction was found to take place both at ambient and at high temperatures (1100°C). Stabilization of Cr(VI) in the dust could be achieved at an optimum sintering temperature of 1100°C for a 50mass% dust : 50mass% clay mixture. Chromium emission during the sintering process was found to be low, and within environmental limits.

Jan 1, 2006

By Roger W. Lee

The commissioning of the prototype Imperial Smelting Furnace (ISF) in 1950 was a technological breakthrough in the pyrometallurgical smelting of zinc and provided significant advantages over the existing retort processes. However, for most zinc concentrates the electrolytic zinc process continued to be more economic. Therefore, the Imperial Smelting Process (ISP) specialised in smelting zinc and lead concentrates that were less amenable for treatment by either the electrolytic zinc process or the lead blast furnace. Subsequently, improved mineral processing techniques led to a decrease in the availability of these concentrates so the treatment of secondary materials in the ISP assumed greater importance. This was facilitated by the development of techniques such as hot briquetting and tuyere injection. In 2002 over 1 million tonnes of zinc and 400,000 tonnes of lead were produced by the ISP. However, in the 2002-3 the economics of the Process became extremely difficult because of low metal prices and increased operating costs. This resulted in the closure of four ISP smelters in 2003 and two in 2005. Nevertheless, two new ISP smelters are scheduled for commissioning in China in 2006 where local economic conditions continue to favour the process. The economics of the process are examined particularly in respect of smelter margin and operating costs. The need to increase the smelter margin means that the future of the process will be closely linked to its ability to consume secondary materials and an examination will be made of its potential for conversion to 100% secondary operation. Apart from a reduction in raw materials costs, a substantial reduction in operating costs would ensue from not operating sinter and sulphuric acid plants.

Jan 1, 2006

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 Ken-ichi Miyazawa

A Center of Excellence (COE) titled the Creation of Nature-Guided Materials Processing, called Nature COE, has been established at Nagoya University. In the Nature COE, a new field of material research is being developed through learning the laws of nature, namely, methods of attaining ?appearance of the maximum function under the minimum substance and energy consumption?, which the nature and living organisms have acquired through their evolution in long period. As one of the specific features, an ?Open Cluster Program? was originated for promoting the researches conducted by young researchers and Ph.D. students with those in and out of the university and also for fostering them, together with such educational programs for Ph.D. students as the research incentive, the oversea training and the international lodging seminar programs. The Open Cluster Program has been found to be effective for fostering of young researchers and students, for promoting their researches, for gathering researchers and knowledge from the world and for propagating the research fruits. Through conducting these programs, world-highest intelligent fruits and a gathering of young minds to lead the new field are expected. In this COE, the researches are conducted on (1) materials used for living bodies, (2) mimicking structures which nature or living bodies are forming and (3) materials processing by mimicking processes to form the structures observed in the nature or the living bodies. These researches are conducted by four groups to extend the processes observed in the natural world to a new type of processing that is thoroughly rationalized by plunging a scalpel of engineering, and to establish a new academic field of materials science and engineering.

Jan 1, 2006