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By Toshihide Takenaka

The management of radioactivated stainless steel from a terminated nuclear reactor will become an important subject in the near future. The separation of the elements in stainless steel should be effective to reduce the management labor. In this study, the separation of the elements in stainless steel by an electrorefining tcchnique was investigated in an aqueous solution. The electrochemical reactions of the elements in stainless steel werc studied by voltammetry and potentio-static electrolysis was carried out. A stainless steel anode was dissolved electro-chcmically with good anodic current etliciency in a chloride solution. The residue, where Ni was concentrated, was found on the anode after electrolysis. The electrodeposit in a stainless steel cathode consisted mainly of Fe and Cr and the Ni content in it was less than 0.5wt% under suitable condition. It is concluded that an electrorefining technique is effective for the separation of the elements in stainless steel.

Jan 1, 2003

By Luben Xie, Lin Hu, Qiang Wang, Min Gan, Tao Jiang, Wenqi Li, Yi Wang, Xiaohui Fan

"The mineralization behaviors of typical fluxes are studied by investigating the microstructures with optical microscope. The results show that the reactions begin with between iron ore and lime, limestone with small particle to form primary liquid. Then coarse limestone, dolomite and serpentine take part in reaction under the action of primary liquid. Limestone is the easiest to mineralization, next dolomite, and the last is serpentine. The higher basicity and smaller fluxes size favor the mineralization process of dolomite and serpentine.IntroductionThe purposes of adding fluxes into sintering are that:(1) to increase the basicity of sinter, so as to reduce even eliminate addition fluxes into BF(blast furnace) and decrease the coke ratio of BF[1,2]. (2) to decrease the melting point of sintering mixture to ensure sintering can be carried out at a lower temperature and reduce the energy consumption. (3) to improve the qualities of sinter by forming binding phase with iron ore fines [3].Flux is another significant component for sinter besides iron ore, especially for high basicity sinter[4]. The proportion of flux is usually higher than 10% in sinter mixture(excluding return mine).There were many reports about the influence of the flux types on sintering, such as limestone, dolomite, lime and so on[5-7]. It is very important to choose suitable fluxes for iron ore sintering. Although the effect of flux size on sintering also has been researched, the mineralization behaviors of the fluxes in the sintering process has not been illuminated. The paper will study the mineralization behavior of fluxes in sintering."

Jan 1, 2011

By M. Kobashi, T. Choh, N. Kanetake

"A new processing route, which enables the cost-effective and energy- saving fabrication of metal matrix composites, have been proposed. The pressureless infiltration of the reactive powder blend with molten aluminum was investigated in this work. The molten aluminum infiltrated into the [Ti + C] powder blend spontaneously, whereas the spontaneous infiltration into the TIC powder phase did not occur under the same experimental condition. The processing time was shortened and· the processing temperature was .lowered by adding the aluminum powder in the [Ti + C] powder. The differential thermal analysis revealed that the aluminum powder in the powder blend melted at 933K and then ignited the reaction between titanium and ·carbon. However there was an .optimum additional amount of aluminum in the powder blend. The TiC formed in situ had three-dimensionally continuous morphologyIntroductionThe squeeze casting process has been used as one of the processing routes for aluminum matrix composites. [1, 2]. Non-reactive metal-ceramic systems have been, generally, used in this technique in order to prevent the degradation of the ceramic phase. Materials obtained by this process basically consist of a continuous metal matrix and discontinuously dispersed ceramic particles. Reactive systems have begun to be introduced into the infiltration process· recently [3A]. Since the ceramics are synthesized in-situ, this process can provide a continuous ceramic matrix [5]. This is one of the outstanding features of this technique in that a bulk ceramic-can be synthesized at relatively lower temperatures in a short time. Another advantage is that the highly reactive combination of a ceramic with a molten metal is in many cases wettable [6], which enables a spontaneous infiltration."

Jan 1, 2000

By Kang-In Rhee

Nonferrous metal recycling not only provides energy saving and environmental benefits but also is a significant factor in the supply of various types of metals used in our society. Recycling plays an important role in establishing the sustainability of materials. The total amount of recycled nonferrous metals by weight accounts for less than 5% but their value is larger than 50% compared to ferrous metal recycling which consists of about half of the total metal recycling in weight. This paper describes trends and typical achievements in nonferrous metal recycling and overviews the present and future of nonferrous metal recycling technology and business in Korea.

Jan 1, 2006

By Alexander V. Suvorin, Vladyslav M. Sokolov

"The traditional technologies for production of the coprecipitated and deposited catalysts are analyzed from the standpoint of diversion of application of the feedstock and increase of efficiency for its usage. The options for return of the metals of spent catalysts to the catalysts production are described. The novel environmentally friendly and cost efficient approach for reutilization of the spent catalysts is realized in practice. It anticipates application along with spent catalysts of the waste generated in the catalytic productions. Reutilization of the Ni-containing catalysts is referred as an illustration. Introduction The recent development of large catalytic manufacturing for organic and inorganic synthesis, and petroleum refinery as well as for applied environmental catalysis has brought about increase and diversification of catalysts production. The generation of spent catalysts has been increased correspondently. The feedstock for production of catalysts is mostly metals in a form of nitrates, carbonates, hydroxides, hydroxydcarbonates. Sometimes salts of organic acids, of ammoniates, of chlorides and of sulphates occur. All these materials are scarce and expensive. So their repeated use by reutilization of spent catalysts is very actual issue. The traditional recycling the Fe-, Cr-, Ni-, Cu- or Zn-containing spent catalysts are carried out by pyrometallurgical reclamation of pure metals or alloys. They can not be used directly in production of catalysts [1, 2]. The hydrometallurgical approach is used for recycling spent catalysts with PGM, W, Mo, Co, Ni or Cu. It provides production of salts of these metals in a form of sulphates, chlorides, carbonates, hydroxydcarbonates and sometimes nitrates or ammoniates. Only a limited number of these salts can be used directly in production of catalysts. Material losses during catalysts production The basic feedstock for manufacturing coprecipitated and deposited catalysts that may be produced from the spent catalysts is aqueous solutions of metals nitrates. Their production is based on application of nitric acid as a dissolvent. About half of it is lost with the flue gases in a form of nitrates vapor and nitrogen oxides (II, IV). The last compound is generated by reaction:"

Jan 1, 2008

By Cheng Pan, Qiugang Yuan, Xuewei Lv, Mei Liu, Enguang Guo

Land-based nickel resources include nickel sulfide and nickel laterite. With the consumption of high grade nickel sulfide, use of nickel laterite has received more and more attention. The mineralogy and sintering behavior of limonitic nickel laterite with high iron and low nickel and silica was studied to offer technical support for producing ferronickel through sintering–blast furnace route. The mineralogy results showed that the main phases in this kind of nickel laterite are goethite (FeO(OH)), gibbsite (Al(OH)3) and NiFe2O4. The TGA (Thermogravimetric Analysis) and DSC (Differential Scanning Calorimetry) revealed hydroxide minerals in addition to absorbed water. After the sintering experiments the chemical composition, phases present (XRD analysis) and physical properties of the sinter were studied. The content of FeO in the sinter increased with increasing basicity up to 1.3, and then decreased with further increase in basicity. The yield of sinter increased (from 73% to 80%) with increase in the basicity from 1.1 to 1.7, and then the yield decreased with the further increase in basicity. Mg(Ni)(Fe,Al)2O4 is the main phase in the sinter while MgCaSiO4 and Fe2SiO4 is the main binder phase when the basicity is 1.1~1.5, and MgCaSiO4, Fe2SiO4 and SFCA is the main binder phase when the basicity is 1.7~2.1.

Jan 1, 2014

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 Keuncheol Choi, Yonghack Lee

"The new lead smelter based on the QSL technology was started operation from May 1992 at Onsan Refinery of Korea Zinc Co., Ltd. The smelter is designed to treat not only various types of lead concentrate but also secondary materials coming from the zinc plant without special pretreatment.Shortly after the start-up of the operation, it has demonstrated that the smelter have a capability to treat wide range of raw materials. Continuous modifications and improvements of the plant are still under way to increase the feed rate and also the ratio of secondary materials to the feed.In this paper, the operating experience and results of QSL smelter, especially the injection of gases and coal to the melt, will be presented with major operation parameters and data.INTRODUCTIONThe QSL lead smelter based on new injection technology was commissioned at the Korea Zinc's Onsan plant from May of 1992. After starting the operation, the QSL lead smelter faced various kinds of mechanical and metallurgical troubles. However, these were gradually worked out by the continuous improvements and efforts.At present, the QSL lead smelter is operated stably at the total feed rate of 57 tonnes per hour with an increased amount of secondary materials."

Jan 1, 1996

By B. A. Paponetti

The following report discusses the bioleaching of chalcopyrite of italian origin catalyzed by Thiobacillus ferrooxidans. The developments vcr.ius time of the main .biochemical and chemical reactions involved in the production of soiuble and insoluble species were investigated focusing on the times at which they begin and bow long they last. The precipitates were characterized both in quantity and in quality relating the rate of the process to the precipitates fonnatiom. A material. balance has been made to verify the proposed mechanism.

Jan 1, 1991

By James B. Pfeiffer

TETRA Technologies, Inc., has applied its HDSIM metals precipitation system to treat a waste stream containing scrubber blowdown and process water from a smelter operation. The combined stream contained cadmium, lead, selenium, arsenic and zinc, plus some iron and copper. Treatment requirements included meeting stringent mass flow limitations for specific heavy metals. The HDS ? system can reduce the arsenic from 600 ppm to less than one ppm. The process generates a dense sludge that can be reprocessed in a smelter, eliminating the liability associated with landfilling. Flow diagrams and process details are discussed.

Jan 1, 1994

By Oleg B. Girin, Yuliya O. Proshenko

"Several approaches to electrolytic synthesis of new types of composite coatings with improved properties were devised using the authors' findings on development of texture, substructure and structural state in metal electrocrystallization. Addressed are texturally composite coatings having improved resistance to wear and corrosion; substructurally composite coatings having improved hardness and corrosion resistance; phase-change constitutionally composite coatings having improved corrosion resistance, reflectance, hardness and resistance to wear; structure-change constitutionally composite coatings having improved electric and magnetic properties; restricted-substructure composite coatings having improved resistance to abrasive-impact wear; and modified-substructure composite coatings having improved strength and plasticity.IntroductionIn recent years, some trends in the formation behavior of crystal texture, crystal substructure and structural state of electroplates were revealed and effects of texture, substructure and structural type on electroplate properties were discovered (1-3). Our interest was in using these findings and effects to develop some ways of synthesizing new types of composite electrolyte coatings having enhanced properties."

Jan 1, 1998

By G. Cifuentes

The kinetics of the electrolytic oxidation of cyanide to cyanate on PbO2-coated stainless steel anodes have been studied by both experimental and theoretical means. The anodes were based on 316 steel and performed in a satisfactory fashion. The pH of the studied KCN solutions exhibited a constant value about 11. Values for all the kinetic parameters have been determined and a mechanism for the studied reaction is proposed.

Jan 1, 1999

By M. Okido, O. Takai, Z. Zhao, M. Ishikawa, R. Ichino, K. Kuroda

"Electrolytic method was applied to calcium phosphate coating on titanium plates as an excellent technique for high density and intensive contact of coated films on biomaterials. The effect of H2O 2 as oxidation reagent on coating characteristics was examined to obtain biomineral films. Solution was containing 7.0 X 10·3 mol/dm3 ofCaC12 and 3.0 X 10·2 of Ca(H2PO4)z, kept at 55 ""C. All deposits were hydroxyapatite (HAp) in this study, independent of H2O 2 concentration, applied cathodic potential and solution pH. In the case of H2O 2 addition, an increase in cathode current started at the low potential, namely, ca. -0.2 V (vs. SCE). In contrast, the current increased at more than ca. -1.4 V in the solution without H2O 2 addition. H2O 2 appeared to be an effective reagent for increasing nucleation density and improving adhesion of deposits on titanium plates.IntroductionIn recent years, many researches have been undertaken to develop the techniques of calcium phosphate coating on titanium or bioglass for medical implantation. High density and intensive adhesion of coating are necessary for adding bioaffinity to these materials and for inducing bone morphogenesis on them when implanted in human body.1) Electrolytic deposition has been a newly developed method as high-speed deposition process. By this method, the supersaturation of calcium phosphate can be increased just in the vicinity of metal substrates and the heterogeneous nucleation is promoted on them. In this process, H2O is reduced according to eq. (1) on the cathodically polarized electrode"

Jan 1, 2000

By Seung-Chul Lee

Transparent conducting tin(1V) oxide thin films have been studies and developed for the electrode materials of solar cell substrate. Fabrication of tin oxide thin films by sol-gel method is process development of lower cost photovoltaic solar cell system. The research is focused on the establishment of process condition and development of precursor. The precursor solution was made of tin isopropoxide dissolved in isopropyl alcohol. The hydrolysis rate was controlled by addition of triethanolamine. Dip and spin coating technique were applied to coat tin oxide on borosilicate glass. The resistivity of the thin film was lower than 0.18-cm and the transmittance is higher than 90% in a visible range.

Jan 1, 1999

By Yuanyuan Zhang, Patrick J. Masset

"The reduction of FexO in slag is one of the fundamental reactions in iron and steelmaking technology, including the blast furnace process (BF). Experiments on the reduction reaction of iron oxide using CaO-SiO2-Al2O3-FexO-C mixtures were carried out using thermogravimetric analysis (TGA) under reducing conditions at temperatures up to 1100°C. The composition of the primary slag was chosen so that the FexO concentration varied between 0 and 75 wt % and the CaO/SiO2 ratio being kept constant to 0.90. From the TGA curves recorded isothermally at different temperatures the kinetic parameters of the iron oxide reduction were determined.IntroductionIn blast furnace the iron ores and coke are charged in layers from the top. The reduction of iron oxide by coke is one of the fundamental reactions in the blast furnace process. Although a great amount of work has been done on the topic of reduction of composites [1, 2, 3], gasification of carbon [4, 5] and reduction of iron oxides by CO [4, 5, 6], the mechanism of reduction in iron oxide - carbon powder mixtures is not fully understood. Fruehan [1] and Rao [2] studied the reaction rate of the reduction of iron oxide by different types of carbon and concluded that the reaction mechanism is controlled by the oxidation of carbon at temperatures up to 1200°C. Rao [2] studied the reaction of hematite with graphite as carbon source up to 1080°C. An activation energy close to 300 kJ/mol was calculated within the temperature range of 950°C to 1087°C. In his study, Fruehan [1] determined the rate of reduction of Fe2O3 and FeO by coal, coke and coconut charcoal as carbon sources within the 900°C to 1200°C temperature range. He found that the reduction of Fe2O3 by carbon occurs in two stages and that the reduction of Fe2O3 to FeO is faster than that of FeO to Fe. This is due to the fact that the CO2/CO equilibrium ratio is higher, and hence, the rate of oxidation of carbon is faster. Fortini and Fruehan [3] have studied the reduction reaction of wustite by graphite and wood charcoal. They found that the wustite reduction can have a significant effect on the overall rate of reduction in composites at high temperatures or in the presence of a large excess of carbon. The calculated activation energy of the reduction reaction by wood charcoal was close to 368 kJ/mol, while the activation energy of the reduction reaction by graphite was 444 kJ/mol."

Jan 1, 2011

By Takaaki Ishikawa

The distribution equilibria of lead, zinc and copper between CaO-Si02-Ah03 melts and liquid copper were measured at 1623K under a controlled H2-C02 atmosphere. The distribution ratios were plotted against the oxygen partial pressure, and reasonable oxide forms dissolved in the melts were estimated from the slopes of the plots. The activity coefficients of zinc oxide (ZnO), lead oxide (PbO) and cuprous oxide (CuO0.5) increased with increasing slag basicity, defined by XCao/Xsio2 The temperature dependence of the activity coefficients was also measured.

Jan 1, 2003

By Sadi Medina

As it is characteristic from Custom Smelters, ENAMl Las Ventanas Smelter has to deal with different qualities and quantities of mining products from about 70 suppliers, that contain a variety of impurities that would be harmful for copper production. In order to increase the smelting capacity, an oxygen plant has been running since September of 1990. Moreover, to improve the environmental conditions, a new sulphuric acid plant started up to neutralize the metallurgycal off-gases from the Teniente Converter and partially from the Peirce-Smith converters. Based on the on-line operation among the reverberatory furnace and the Teniente Converter using oxygen enriched air to produce high grade matte, most of the volatilizing impurities, mainly arsenic, are collected as discarding compounds in the gas cleaning system of the acid plant. This paper describes the continuous performance of the Teniente Converter with acid plant, the results attained, the operation problems and how they were solved. The impurities distribution achieved in this process is also included.

Jan 1, 1993

By Yasuo Kudo, Wu, Hayato Sato, Hiroshi Nakazawa, Shouming

"In order to recover copper from a waste nickel condenser powder, bioleaching experiments were carried out using Thiobacillus ferrooxidans in a shaking flask. The content of nickel and copper in the waste nickel condenser powder in this study were 8.0% and 3.5%. X ray analysis showed the peak of barium titanate. In the preliminary study using metal nickel and copper powders , the dissolutions of nickel and especially copper were accelerated with the addition of ferric iron in the bioleaching of nickel and copper powders while not in the absence of ferric iron. Ferric iron oxidizes both metals, and Thiobacillusferrooxidans oxidizes ferrous iron resulting from the oxidation of metals, whereby the dissolutions of metals proceeds. The dissolution rates of nickel and copper increased with increase in the concentration of ferric iron in the bioleaching of the waste nickel condenser powder.1. IntroductionNickel condensers rejected from manufacturing plants are crushed and landfilled. Waste nickel condensers contain nickel and copper and could be considered as nickel and copper ores. Since the capacity of landfills is diminishing, it is required to recycle metals of waste nickel condensers in order to reduce the amount of wastes landfilled. Conventionally, metals in the waste were recovered by dry metallurgy after the incineration.Nickel has been refined by solvent extraction - electrowinning method (SX-EW method). Recently the amount of copper refined by SX-EW method has increased (Takahashi, et al. 1994). This method is cleaner and consumes less energy than conventional methods. Nickel dissolved well in acid solutions, but copper is not. If copper is leached efficiently from a waste nickel condenser powder, SX-EW method will be applied to recover copper from them"

Jan 1, 2000

By Raymond M. Coveney

Bedded sulfide ores in Cambrian Chinese black shales typically contains at least 2% Ni, 4.5% Mo, 1% As and 0.2% Se. Thin laminae and replaced on colites from the ore contain intimate mixtures of fine-grained Ni-rich sulfides and jordisite complicating ore treatment. The ores contain abundant jordisite, vaesite, nickelian pyrite, and barite and lesser amounts of sphalerite, gersdorffite, millerite, tennantite, fluorite, chalcopyrite, and HgSe (probably tiemannite). At present only ores that are sufficiently rich (>4.5% Mo) for direct roasting are mined and treated to produce, ammonium molybdate. The ores contain Pt, Pd, and Au in amounts totaling up to -2.5 ppm, but these are not recovered.

Jan 1, 1993

By Dao-Wu Yang, Ju-Lan Zeng, Li-Xian Sun, Yan Yao

"The hydration heat of the pure cement, the fly ash single-dopped cement, as well as the fly ash and fluorgypsum co-dopped cement were investigated by means of micro-calorimety with an eight-channel micro-calorimeter (TAM Air). The results showed that the hydration heat and the hydration rate could be reduced significantly by fly ash and fluorgypsum. However, the reduction was not proportional to the loading of dopant. The exothermic peak of the fly ash and fluorgypsum co-doped cement was appeared earlier than the fly ash single-doped cement. As the temperature decreased, the hydration heat and the hydration rate of the doped cement were reduced, and the exothermic peak appeared later. The effects of fly ash and fluorgypsum on the compressive strength of cement were also investigated. The results revealed that the early compressive strength of concrete made up of the co-doped cement was largely higher than that of the fly ash single-doped cement. Based on the experiment results obtained in this paper, we could conclude that fluorgypsum is a suitable additive for fly ash-doped cement.IntroductionFly ash and fluorgypsum are industrial waste. In 2008, nearly 400 million tons of fly ash has been produced by coal-burning power plants in China. And it is estimated that this number would exceed 500 million at the year of 2015. Besides, every year the fluoride salt factories in China discharge more than 100 million tons of fluorgypsum. Tremendous of fly ash and fluorgypsum occupy considerable land and contaminate air and water sources [1]. As a result, comprehensive utilization of this two industrial waste has draw great attention from all over the world.Cement is the most-used construction material on earth. But the production of cement consumes huge energy and destroys the environment. This problem might can be partly solved by applying fly ash and fluorgypsum as additive for cement [2-4]. During the last decade, some papers that focused on applying fly ash and fluorgypsum as additive for cement have been published [5, 6]. However, to the best of our knowledge, none of these papers investigated the hydration heat of the fly ash and fluorgypsum co-doped cement.The hydration of cement is an exothermic reaction, which can result in serious problem for mass concrete: The interior of the concrete could reach very high temperature as the hydration proceeded [7-9]. As a result, the great temperature difference between the interior and the outer of the concrete would exist and cause serious thermal stresses. Thus, the concrete would be destroyed by the cracks which in tum are resulted from the thermal stresses [10, 11]. The heat released by the cement hydration and the hydration rate is commonly regulated by adding mixed materials or transferring additive such as fly ash and fluorgypsum [12-14]."

Jan 1, 2011