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By Eiichi Kuzuno, Atsushi Shibayama, Toyohisa Fujita, Kazuo Koike, Toshio Miyazaki, Hitoshi Masuda

"A solid sulfur is more useful to recover and store than a sulfuric acid as a by-product in the zinc hydrometallurgy. In this experiment a zin concentrate (sphalerite) was leached with ferric sulfate at about 373 K for 3 to 6 hours. Zinc was leached more than 95%. After a solid-liquid separation, the leached residue contained solid sulfur was obtained. The particles in the residue were dispersed by lignin and the solid sulfur of approximately 85% was recovered as float product by a flotation with frother in the pH 4. The dried float product was heated at 413K for 2 hours. The pure solid sulfur was recovered. On the other hand in the leached liquid a zinc oxide was ·added and ferrous .iron was oxidized to ferric iron by blowing oxygen. This ferric iron was returned to the zinc leached process after solid-liquid separation.IntroductionZinc concentrate is usually roasted as pretreatment in zinc hydrometallurgy and the produced S02 is changed to sulfuric acid. However, recently in Japan the utilization of sulfuric acid has been limited and it is more costly to store. Instead of producing sulfutic acid the solid sulfur recovery has been examined by direct leaching of zinc_ concentrate in this experiment.In the direct leaching, several kinds of effects have been studied for leaching of sphalerite in ferric sulfate solution. The addition of lignine siilfonate1 • 2) and fine· grinding3) increases the · speed arid leaching fraction of sphalerite. The leaching ratio depends on impurities in sphalerite ores4 • 5). Here, the zinc concentrate is leached ferric sulfate solution under atmospheric pressure at 373K. The solid sulfur in leached residue is separated as float products from other solids by sink-float separation and flotation. The sulfur in float products is purified by evaporation at 413K and recovered."

Jan 1, 2000

By Jian Wang, Hongyang Cao, Binxiu Wu, Junhong Li, Jimin Wang

"The enrichment and separation of scattered metal indium component in the pressure leaching solution with sulfuric acid from vacuum furnace germanium slag were studied by iron substitute and P204 extraction, which is supplied by shaoguan smelter. The experimental results show that the extracting power of P204 for indium from pressure leach solution is powerful. The optimal technological condition were the ratio of P204 and sulphonating serosene 3:7, phase ratio 1:3, solution pH 1.2, and extracting 5 minute. The enrichment indium solution of 21.7 g/L In at 95.2% recovery ratio was obtained by three-stage counter flow extraction and four- stage counter flow stripping.IntroductionScattered metals, such as Indium and germanium, were inriched as intermediate product or by-product during the metallurgy process of other non-ferrous metals, such as lead, zinc, copper and tin. For example, the indium and germanium were inriched in vacuum furnace germanium slag, which is the by-product of zinc vacuum distillation operation from hard zinc. It is difficult to recovery the indium from the vacuum furnace germanium slag, because the indium content is low, and the chemical composition and phase compositon were complex.Recovery indium from bearing indium zinc slag was researched extensively, such as pressure acid leaching, high temperature evaporation, solvent extraction method[l-7], acid leaching method has the advantages of high leaching rate, which can be separated hydrochloric acid, sulfuric acid and silicon fluoride acid systems. Solvent extraction method has the advantages of low production cost, fast reaction speed, high enrichment ratio, and simple operation."

Jan 1, 2013

By Yong .. Jun Wu

Laminated ceramics have received widely scientific and commercial attention because their properties, such as mechanical properties and electrical properties, can be tailored by adjusting the structure, thickness and composition of the different layers. For example, ferroelectric Bi4Ti3O12 (BIT) which has a positive temperature coefficient of dielectric constant (,E) can be used to modify the negative tE of typical microwave dielectric ceramic BaNd2Ti4O12(BNT), However, BaNd2Ti4O12/Bi4TiO12/Bi4Ti3O12/BaNd2Ti4O12 (BNT/BIT/BNT) laminated ceramics could not be prepared by the general method because the optimal sintering temperature of BaNd2Ti4O12 ceramic (around 1350°C) was much higher than that of Bi4Ti3O12 ceramic (around 1100°C). In this research, a new method of spark plasma sintering (SPS) combined with post-sintering was successfully proposed to prepare BNT/BIT/BNT laminated ceramics. It was divided into three steps. In first step, the BaNd2Ti4O12 ceramics were prepared by conventional sintering method. In second step, the calcined and pre-pressed Bi4Ti3O12 powders were sandwiched between BaNd2Ti4O12 ceramic pellets and spark plasma sintered at 900°C for 10min to synthesize BNT/BIT/BNT composite ceramics. In the last step, a post-sintering was employed to reoxidize the partially reduced BNT/BIT/BNT composite ceramics. The results of scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) showed that BNT layer and BIT layer were well bonded and no significant interfacial infiltration between them was observed. The sandwiched BNT/BIT/BNT ceramic with 10.7% BIT in volume has a dielectric constant of 92.85, a low dielectric loss of 01068 and a small temperature coefficient of dielectric constant of 35 ppm/°C at MHz.

Jan 1, 2003

By Tomoji Kawai

"The Pulsed Laser Deposition method using multi-targets is extremely useful for the creation of functional multi-layers and variety of artificial lattices. The topic of the present talk is on the creation of ''Function hannonized artificial lattices by laser ablation"" made of the combined magnetic, ferroelectiric and superconducting layers. The outline of talk is,1. Features of Pulsed Laser Deposition method (Laser Molecular RHEED and S1M/AFM.2. Creation of magnetic, dielectric and superconducting artificial lattices by Pulsed Laser Deposition.3. Novel properties of function harmonized artificial lattices: especially on the magnetic and magnetoresistive artificial The outline of talk is, lattices made of3d transition metal oxides."

Jan 1, 2000

By Chen L. Lin

Scientific visualization is an ideal methodology for investigating complex phenomena that are characterized by large amounts of data. Furthermore, it is invaluable in the study of processes that evolve in time. Scientific visualization relies heavily on computer graphics, image processing and video technologies. Specific applications of scientific visualization in the minerals and materials processing fields that are considered in this paper include: 1) applied CT technology for multiphase materials and minerals, 2) time averaged density profla in air- sparged hydrocyclone (ASH) flotation and 3) dynamic motion analysis of ball mill grinding.

Jan 1, 1993

By Michael P. Meisel

Solinox is a physical scrubbing process capable of removing a number of noxious materials from off-gasses, especially SO2, hydrocarbons, halo¬gens, heavy metals such as dust, etc. As these materials are dissolved physically, (not chemically bound), the solvent is absolutely stable and no by-products are formed in the scrubbing cycle. The process has been installed in three plants up to now, treating from approximately 30 MMSCFD to approximately 100 MMSCFD. These installations are in a non ferrous metal smelting operation, in a cellulose factory, and in a roasting process.

Jan 1, 1992

By Michael P. Heisel

Solinox is a physical scrubbing process capable of removing a number of noxious materials from off-gasses, especially SO2, hydrocarbons, halogens, heavy metals such as dust, etc. As these materials are dissolved physically, (not chemically bound), the solvent is absolutely stable and no by-products are formed in the scrubbing cycle. The process has? been installed in three plants up to now, treating from approximately 30 MMSCFD to approximately 100 MMSCFD. These installations are in a non ferrous metal smelting operation, in a cellulose factory, and in a roasting process.

Jan 1, 1992

By A. V. Tarasov

In the course of research aimed at improving the performance of the Vanyukov smelting process (VP) for treating sulfur raw materials in a pilot-scale furnace it has been found that an increase in the calcium oxide content up to 12% to 14% in case of smelting to produce high-grade matte results in a decrease in the copper content of slag by 0.05% to 0.3%. The residual copper content of slag can be computed by a formula taking into account an increase in the calcium oxide content of the feed material and that in the slag. In the course of research for improving the performance of the zinc-containing slag fuming process with blowing of the slag bath with combustion products of natural gas it has been found that the silica and calcium oxide contents have an effect on the degree of zinc sublimation. In case of slag containing 24.4% SiO₂ and 6.95% CaO by weight (SiO₂:CaO = 3.51), the residual zinc content of slag was 3.25%. The minimum residual zinc content of 1.95% was obtained in case of slag containing 22.5% SiO₂ and 14.5% CaO by weight (SiO₂:CaO = 1.55). An increase in the CaO content of slag up to 16% by weight with a ratio of SiO₂:CaO = 1.25 to 1.35 permits minimization of zinc losses in slag by achieving a residual zinc content of final slag in the order of 1%.

Jan 1, 2006

By M. Urda-Kiel

Stainless steel is increasingly used as a cathode starting sheet. It was shown earlier that even when depositing copper on copper, a substrate-influenced zone appears in the deposit structure, followed by a transition zone and finally by the electrolysis-influenced structure. On copper, the substrate-influenced zone has a thickness of twenty micrometers and on titanium, eventually more than fifty micrometers. Initial nucleation and growth have a considerable influence. In this paper, copper was deposited in a channel cell on four different 304 stainless steel substrates: mechanically polished and anodized, respectively, at 0, +400 and +800 mV/SHE in 1M H2SO4 at 20°C. Copper was deposited under electrowinning conditions after solvent extraction (SX) (40 g/l Cu++, 180 gh/l, H2SO4, 20 or 60°C). The results showed that, although Auger surface analyses of the substrates were only slightly different one from another including the oxide thickness, nucleation and initial stages of growth were very sensitive to the surface treatment of the substrate. Potential step and current step methods gave similar results : progressive nucleation followed by 3D diffusion controlled growth. The highest nucleation frequency was observed on stainless steel anodized at 0 mV/SHE, under various electrolysis conditions. The potential influence of these findings on industrial practice is discussed.

Jan 1, 1999

By Terry C. Cheng

The Akita Hematite Process is currently the only hydrometallurgical iron removal process producing saleable iron by-products in the zinc industry. In this study, McGill University and Akita Zinc Co. have worked together into elucidating the basic precipitation chemistry of the process from the standpoints of hematite product quality and prevailing precipitation kinetics. This work determined that hematite is produced under the applied conditions (T = 195?200oC,PO2 = 103?414 kPa) directly without prior formation of basic ferric sulphate and transformation of the latter to hematite as thought originally. The rate-limiting step responsible for the long retention time (~180 min) was found to be either the re-dissolution of ferrous sulphate according to the batch reactor studies, or the slow hydrolysis of the remaining ferric sulphate according to the continuous reactor studies. Another interesting contrast between the batch and continuous reactor data was the degree of sulphur contamination (1.5 vs. 3.8%, respectively) and the specific surface area of the product (10 vs. 30 m2/g, respectively). These differences in addition to the co-precipitation of SO4-containing phases such as jarosites, alunite, and anhydrite were attributed to the significantly higher supersaturation level prevailing in the industrial continuous autoclaves that yields highly aggregated sub-micron hematite crystallites contaminated with chemisorbed sulphate ions.

Jan 1, 2003

By J. P. Ibáñez

The uptake of copper from extremely dilute aqueous solutions by alginate in the form of protonated dry alginate beads was investigated. Barium was used to cross link the alginate forming the beads. The effect of various experimental parameters such as pH and metal ions concentration on the uptake of copper were studied. The uptake was strongly dependent on the Cu-bearing solution pH up to a value of 4.5. A removal of 100% o was achieved when the initial concentration of copper was as low as 8.0 mg/L. The maximum uptake, i, e., the loading capacity, was found to be 167 mg of copper per g of beads. The mechanism governing the removal of copper was found to be ion exchange between protons of the alginate beads and cupric ions of the solution. For this ion exchange process a molar ratio, d[H+]/d[Cu2+], of 2.0 was determined. EPMA-EDX analysis of the Cu-loaded beads showed a uniform distribution of the ions throughout the structure of the alginate, regardless the solution pH. This may suggest that this sorbent material is a porous ion exchanger having high permeability and capacity. The uptake of copper and of the heavy metals cadmium and zinc by this sorbent is compared.

Jan 1, 1999

By Johannes Boonstra

High rate bacterial catalyzed processes can serve to improve hydrometallurgical operations. These solutions are not only economical but also environmental sustainable. With references around the globe, the value of this new approach is recognized by industry worldwide. For instance, metals can safely and economically be separated from process and waste streams using biotechnologically produced sulfide, recovering a valuable metal sulfide product instead of a waste gypsum stream for disposal. Both the natural biological sulfur and nitrogen cycles offer bioconversions that are applied on industrial scale. The shared advantage of these processes is that waste compounds are converted in either a reusable raw material or in a harmless product. This way, natural product cycles can be closed. Applications based upon bioconversions are for example: Sulfur based: Bioleaching, reduction of oxidized sulfur compounds to elemental sulfur, metal recovery with biogenic produced H2S, SO2removal from gas streams, etc. Nitrogen based: Ammonia removal using the anammox-process, biological removal of NOxfrom gas streams, nitrate removal from water streams, etc. Metals: Bacterial processes for the reduction of metals such as uranium, selenium and manganese have proven to offer great potential for clean-up of groundwater streams. This paper contains a description of the above applications. Further, a short introduction on engineered high rate bioreactor systems and a description of industrial biotechnological applications will be provided.

Jan 1, 2003

By Ch. -A. Gandin, M. Rappaz

"The grain selection mechanism which occurs during the growth of columnar dendritic structures is routinely used in the investment casting industry to produce directionally solidified (DS) and single crystal turbine blades. However, the evolution of the grain density with increasing distance from the chill has rarely been correlated with the evolution of the grain texture. This contribution presents a three-dimensional (3-D) stochastic modeling approach which permits the computation of grain maps, pole figures and grain density evolutions in DS superalloys. These predictions are compared with measurements resulting from an automatic indexing technique of Electron Back-Scattered diffraction Patterns. This 3-D stochastic model, which applies to uniform temperature situations, has to be extended to the dendritic growth in a thermal gradient. As a preliminary step, a 2-D Cellular Automaton (CA) has been coupled recently to Finite Element (FE) heat flow computations in order to predict the grain structures in complex shape investment cast part. The application of this CAFE model to the investment casting of a turbine blade is presented. Considering these results, the extension of the CAFE algorithm to three dimensions is discussed.INTRODUCTIONThe selection of columnar grains during the directional solidification of alloys plays a key role during the investment casting of directionally solidified (DS) and single crystal (SC) components for aerospace applications [I]. This selection mechanism, leading to a competition of the dendritic network propagation at grain boundaries, has been the subject of many investigations. In particular, the study of Walton and Chalmers [2] is remarkable since it provides a link between the evolutions of the density and of the texture of columnar grains with increasing distance from the mold wall. Since this original work of Walton and Chalmers, two new tools have become available, which enable one to revisit the problem of grain selection in much greater depth. The first one is a fully automatic indexing technique of Electron Back-Scattered diffraction Patterns (EBSPs) [3-6] which directly gives the crystallographic orientation of the solid at any location of the specimen. Pole figures, orientation distributions, misorientations between grains can be visualized very easily with this technique. This information can be directly compared with the results of a second tool: a three-dimensional (3-D) stochastic model (SM) describing the nucleation and growth of grains in a uniform temperature field [6-9]. In order to extend this model to non-uniform temperature situations, a preliminary 2-D model has been developed [10]. It is based on a Cellular Automaton (CA) algorithm coupled with Finite Element (FE) heat flow computations. Since the details of both the automatic indexing technique of EBSPs and the simulation tools have already been published [3-10], only a brief summary is given here."

Jan 1, 1994

By Anatoly Sudnev, Vladimir Skorohodov, Igor Kudryavtsev, Boris Radionov, Dmitriy Panov

"In cobalt production technology at a stage of solutions purification manganous cake (slime) basically containing hydroxides of the specified metals is formed. The possibility of full cobalt recycling in the basic technology of metal production at slime processing with generation of pure manganous compounds is shown. After slime dissolution in sulfuric acid in the presence of reducers the solutions containing cobalt, manganese, nickel and other nonferrous metals are formed. Optimum conditions of selective precipitation major part of cobalt by sodium hydroxide from the obtained solution are defined, thus more than 95% of manganese are remained in the solution. The cobalt precipitate is directed to the basic technology and the solution is purified by sorption. The most effective sorbents are chosen, optimum modes of its use are found. Examples of manganese recovery from the purified solutions as MnO2, MnCO3, Mn(OH)2 with a ratio manganese : impurities more than 3000 are presented.In the processes of hard alloys manufacture and processing of cobalt-bearing primary raw materials various cobalt-manganous slimes are formed. After leaching by solutions of mineral acids the problem of cobalt and manganese separation becomes an actual. The common way of metals separation in a solution is the Shreyber’ alkaline method allowing rather selectively to precipitate of cobalt hydroxide by sodium hydroxide. However this way does not allow separating completely target metals because of transfer of some manganese in the hydrated precipitate, even at its rather low content.In the given work the results of researches to improvement of a traditional way by inclusion to hydrometallurgical technology of operation of sorption separation of the specified metals are presented. The main goal is definition of conditions to achievement of the complete removing cobalt at hydrolysis with the minimum sedimentation of manganese and the subsequent additional recovery of cobalt by ionites from the obtained solutions."

Jan 1, 2008

By Xuyang Liu, Xuewei Lv, Chenguang Bai, Meilong Hu

"The electro-deoxidation process for ilmenite concentrate in molten salt was studied by cyclic voltammetry and AC impedance spectroscopy. The results from cyclic voltammetry are consistent with those of AC impedance spectroscopy. The results showed that the electro-deoxidation process for ilmenite concentrate consists of two steps. In the first step, Fe is reduced from the ilmenite concentrate. The second reaction is the decomposition of TiCh. CaTiCh is an intermediate product. At low voltage, the electrochemical reaction is the main step. With the increasing potential, the diffusion of ion is the main rate controlling step for the electro-deoxidation of FeTiO3.IntroductionTitania and titanium-rich products are mainly prepared from ilmenite concentrates (FeTi03), which contain about 40%-60% T1O2 after ore dressing and other physical or chemical processes [1]. At present, the main methods to prepare titania are the sulfuric acid process and the chloride process, but the sulfuric acid process consumes a large amount of sulfuric acid and the materials requirements for the chloride process are strict [2], Since the Electro-Deoxidization in Molten Salt (FFC) method was put forward in 2000, many researchers have successfully extracted the metal and alloys by this method, such as Ti, Cr, Tb, Si, Al-Si, TiV, FeTi, etc. [3-7], FeTi alloy is a typical hydrogen storage material, and because of its favorable properties, the preparation of FeTi alloy has become a hot research topic [7-9]. However, the mechanism of electro-deoxidization has not been studied thoroughly [10-11]. Therefore, in this study, the electro-deoxidation process for titanium concentrate was investigated by electrochemical methods, and the study makes a contribution to improving the current efficiency of the electrolysis."

Jan 1, 2012

By Md Sazzadur Rahman

Electrochemical Impedance Spectroscopy studies were conducted on two organic thermal energy storage materials; Neopentylglycol (NPG) and 2-Amino-2-Methyl-1,3-Propanediol (AMPL). The ionic conductivities and dielectric relaxation times in the low temperature ordered a-phase (monoclinic for both NPG and AMPL) as well as high temperature orientationally disordered cubic y-phase are reported.

Jan 1, 2006

By Michael L. Sorokin

The metallic nickel production by converting of nickel matte is analysed from the thermodynamic point of view using earlier developed thermodynamic models for sulphide, metal and slag phase. Three-suffix Margules equations are used to calculate thermodynamic properties of melts. Potential diagrams of Ni-FeS-OSiO2 system are calculated for various temperatures and Fe to Ni ratios. The diagrams used for consideration about possibilities of the direct one-stage metallic nickel production.

Jan 1, 1995

By Fashina Olugbenga Emmanuel, Ghazali Akeem, Adegbola Adekunle Amos, Omotoyinbo Joseph Ajibade, Olaniran Oladayo

"Modern engineering materials are required to be light weight and corrosion resistant, coupled with high strength and hardness. In this work, Al formed the parent metal and alloyed with 2.03% of Copper by sand casting process. The cast product 2024 was warm worked at various temperatures ranging from 300 to 5600c at 5%, 10%, 15% and 20% deformation respectively and aged accordingly. The results showed that the mechanical properties vis-à-vis hardness, tensile improved with increasing % deformation at a higher temperature. This was due to the progressive close-up of the voids emanated from casting by increasing deformation which is evident from the micrographs. MATLAB was also adopted to generate a model capable of determining the trend of flow of stress at operating temperatures. This was of immense value due to an increasing impact at higher percentage deformation with temperatures. Hence, Al -alloys will find applications in land vehicles, ships, trains, and aircraft, at elevated temperature.INTRODUCTIONThe problem of safe vehicle design with maximum impact energy absorption is a significant subject in structural crash worthiness design [1]. All engineering designs are expected to ensure the safety of users' life. This informed several studies meant to probe the causes of component failures in equipment, vehicles, and aerospace design and decide on appropriate solutions through materials selection techniques. A common example is in the design of crankcases and heads, piston, and cylinder blocks. As with engine blocks, cylinder heads can be made of Cast Iron or Aluminium Alloy. A head made of Aluminium alloy is lighter in weight than if it were made of Cast iron [2]."

Jan 1, 2013

By Hideyuki Takahashi, Taro Aichi, Kazuyuki Tohji, Makoto Muramatsu, Rie Sato

"There are several ways to condition lead-based alloy anodes for zinc electrowinning: electrochemical treatment, chemical treatment and physical treatment. Two advantages of physical treatments are their productivity and variety. In this report, physical treatments, including blasting with silica, alumina, steel grit and cut zinc wire, were tested. The laboratory tests confirmed there were differences in the formation of anode scales during electrowinning and in the suppression of lead dissolution from the anodes. With an increase in the surface roughness, the misfit between the PbC""2 and the MnC>2 was mitigated and the anchor effect was promoted; these effects resulted in dense Mn oxide scales on the anode.IntroductionZinc is widely used for hot-dip zinc plating and for die casting alloys. As a supplier of materials, we have endeavored to produce zinc that is economical and contains as little impurity as possible. As a result of our efforts, a technology for consistently providing special high-grade (SHG) zinc has been established. However, as seen in the issuance of the Restriction of Hazardous Substances (RoHS) Directive, public awareness of the industrial impact of heavy metals on the environment has been heightened. Increasing efforts to control environmentally sensitive substances will be necessary for our production processes.Electrolytic SHG zinc is produced by electrodeposition in an acidic solution with a Pb-Ag or Pb-Ag-Ca alloy for the anode and an Al alloy for the cathode. Pb alloy anodes are widely used because of their excellent durability; however, they are a source of Pb, which is the main impurity of the product."

Jan 1, 2012

By Lijuan Li, Xin Xia, Junjun Huang, Qijie Zhai, Xiang Jiang

"Some experiments with different temperatures (1173, 1223, and l273K) and different annealing times (3, 4, 5, 6min) were carried out on cold-rolled plate of Fe-36Ni invar alloy. The microstructure and the mechanical properties were observed and tested respectively, and the fracture morphology was observed by SEM. The results show that with increasing of the temperature and the annealing time, the austenite grains gradually grow up accompanied by a small amount of annealing twin crystals, meanwhile, its plasticity and toughness are improved, and it is typical ductile fracture under the condition of tensile failure. After annealed at l223K, the invar alloy has better comprehensive properties than that at the other annealing temperatures, and the grains size is more uniform. Furthermore, when the annealing time is 4min, the invar alloy has the best comprehensive properties.IntroductionAs we known, most metals and alloys expand with increasing temperature. More than one hundred years ago (in 1897), Guillaume observed that Fe-Ni alloy with face-centered cubic (fcc) crystal structure, consisting of36%Ni, showing a very small thermal expansion coefficient below the ferro-to-paramagnetic transition, the thermal expansion coefficient around room temperature( <2 X 1O-6K-1 compared to most metallic materials which have a thermal expansion coefficient of 10-20 X 1O-6K-1) [1,2]. Since then, the subject has attracted many researchers, and various alloys with low thermal expansion coefficients have been developed. These alloys, generally known as ""invar alloys"", are in demand where dimensional changes due to variation in temperature must be minimized and where high stability is required [3, 4]."

Jan 1, 2012