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By Yuri Gelfgat

"This paper presents some results of the investigation of the steady magnetic field influence on hydrodynamics and heat/mass transfer in processes of semiconductor single crystal growth (Si, Ge, InSn). The investigation employed mathematical and physical simulation techniques of relevant processes and full-scale experiments on growth facilities. A number of additional MHD phenomena have been found generated in the melt due to the rearrangement of flow pattern, the formation of specific convective cells, and the origin of MHD boundary and shift layer.IntroductionMagnetohydrodynamic (MHD) means of creating forces by contact-free methods in liquid conducting media have been widely used in the production of volume semiconducting single crystals. The goal of this method is to control convective transfer processes in the melt volume and on the crystallization front [1-3]. This is due to the sufficiently high conductivity of semiconductor melts (s = 104 /106 O1m-1 ) and an obvious relationship between the hydrodynamics in the melt and at interfaces and the conditions of formation of single crystals and their quality [ 1].All types of MHD effects rest upon the generation of volume electromagnetic forces in the melt by various means as well as on the possibility to direct them arbitrary in space and to adjust easily their absolute values. Fig. l presents different means how to implement MHD phenomena during single crystal growth. It should be emphasized that in all the modifications given in Fig. l additional energy introduced into the melt cannot influence directly the crystallization process since it is incomparable to the energy of molecular forces. Both the influence and efficiency of MHD means are determined solely by the change of motion, heat and mass transfer characteristics."

Jan 1, 1998

By Kazuyuki Kakegawa

The sintering characteristics and the change in the compositional distribution in the PbTiO3 PbZrO3-Pb(Mgl/3Nb2/3)O3 system during the sintering process by spark plasma sintering (SPS) method were examined. They were compared with those by a normal sintering method. The densification by the normal sintering was slow even at high temperatures, When SPS method was employed, much lower temperature and shorter period resulted in sintered bodies having almost the theoretical density. As expected in normal sintering, the compositional distribution decreased as the sintered density increased. On the contrary, the change in the compositional distribution by SPS was much smaller than that in the normal sintering. This sintering characteristic of SPS suggested a possibility of fabrication of sintered material having a desired compositional distribution.-

Jan 1, 2003

By Lv Guozhi, Niu Liping, Shi Guanyong, Liu Yan, He Jicheng, Du Yanjun, Dou Zhihe

"We proposed thermit reduction-electroslag remelting method of preparing the large scale CuCr alloy. But there are pores and oxide inclusions in CuCr alloy prepared by thermit reduction process. This paper studied mainly the effects of ratio of reactant and additive on the inclusion type and their occurrences in CuCr alloy. The alloy prepared in different process conditions was characterized via XRD, SEM, OM and TEM and metallographic microscope, in which the existing state and micro-structural defects of inclusions are analyzed. The results show that there are three distinct regions: copper-rich regions, chromium-rich regions and the inclusion regions. Inclusions are mainly in the form of stomata and Alz03 phase, mainly locating in the copper-rich phase and the interface area of chromium-rich phase and the copper-rich phase. Adding Na3AlF6 and heating agent can effectively reduce the inclusion content in the alloy.1 IntroductionIn recent years, with the development ofhigh power vacuum and high-pressure technology ,the CuCr alloy contact material which has many advantages gradually replaced the traditional W-Cu and Cu-Bi series alloy contact material, and become the first choice of material in high-voltage and high-power vacuum switch contacts['-3l. The traditional powder metallurgy method, infiltration method and vacuum arc melting method[4-SJ are using metal Cu powder and Cr powder as raw material by casting molding, and have disadvantages such as high production costs, complicated process, poor product density and low yield, especially in the large size alloy ingots[9-12l. At present, the world regards CuCr alloy new preparation technologies as the first place, and how to achieve a large size the CuCr alloy ingot preparation has become a hot research of CuCr alloy[3l. Zhang Ting-an and Dou Zhihe[l-3l who are supported by national natural science fundation of china successfully successful developed new technologies and core equipment to prepare large-size copper-chromium alloy through aluminum thermal reduction-secondary refining method, and obtained two national invention patents. The method includes two key steps: one is get CuCr alloy consumable ingot by Thermit-SHS with electromagnetic stirring, the other is to refme the CuCr alloy ingot to remove the pores, inclusions and other defects by electroslag remelting technology to get dense and uniform CuCr contact material. The preliminary study results show that means of electromagnetic stirring evidently inhibit effect of alloy ingot macrosegregation during the electromagnetic casting stage, but there are still microstructure defects such as alumina inclusions and pores in the alloy ingots. Therefore, Zhang Ting-an et al refer new ideas of using the electroslag remelting to refine Cu Cr alloy ingots and effectively remove the defects of the ingots such as pores and inclusions [3l _ At present, there is no report of study on the electroslag remelting refining processes of CuCr alloy (the refining slag, remelting current). This article will research mode of occurrence and distribution law of inclusions in the large-size CuCr alloy ingots by Al Thermit-SHS under magnetic field stirring action and provide a theoretical basis for chosing refining slag to remove inclusions by electroslag refining. Meanwhile the article analyses the effect of reduction conditions of Thermit-SHS on the types of inclusions, mode of occurrence and distribution of regular inclusions in alloy ingot, and refer theory for inclusions regulation in the large-size alloy ingots."

Jan 1, 2013

By Tianzu Yang, Weifeng Liu, Shu Bin, Lin Chen, Wanda Bin

"Vanyukov Process has been mainly applied for processing copper and nickel sulfide ore for more than 30 years. Based on the understanding of the Vanyukov Process, researchers from China introduced the technology into the areas of lead, antimony and bismuth extraction by changing the furnace structure and technical flow, which greatly extended the application area and raised the processing efficiency, thus developed the oxygen-rich side-blow bath smelting (OSBS) technology in 2000. This contribution reviews the history of OSBS technology from four respects: the quantity, the furnace structure, the process flow and the application area. Its potential research direction and industrial application are also summarized.IntroductionVanyukov bath smelting furnace and related bath smelting technology were developed by researchers from Soviet Union who devoted comprehensive research on fundamental theory as well as engineering technology [1,5]. Vanyukov process has been applied for large industrial production since the 1970s and it is still one of the major methods in modem pyrometallurgy process. The appearance ofVanyukov double district furnace and joint double furnace in the past ten years, which are applied for copper smelting, is the most valuable advances of the Vanyukov process [7,8,9]. However, the application ofVanyukov process was limited in copper and nickel sulfide ore smelting, and few countries adopted this process except Soviet Union."

Jan 1, 2013

By Leonard Harris, Rosa H. Harris

"It is becoming increasingly obvious to mining and exploration companies, when operating overseas, that their activities should not conflict with the interests of the surrounding communities. The world's largest gold heap leach operation, Minera Yanacocha has installed community assistance programs in Peru concerned with health, education, electrification, agricultural assistance and road improvements. The programs are conducted with joint venture partners consisting of the company, the community people, the contractors and suppliers, government and non government organizations and a ladies association composed of the employees' wives and female staff.IntroductionThe l 990's is the decade highlighted by enormous investments in mineral exploration and mining projects in the developing world. Figure 1 illustrates the distribution of exploration spending by mining companies in 1995."

Jan 1, 1997

By Gabriel Zarate

Mantoverde is a heap leach-SX-EW plant that was commissioned in December 1995 at a production rate of 42,130 tonnes of copper per year and 5.4 million tonnes of ore per year. Copper production was steadily increased reaching a maximum of 62,239 tonnes in 2012 for an ore throughput of 10,5 million tonnes. In order to get these production and throughput rates, a number of changes have been made in the metallurgical parameters of the plant operation since the start up, among them particle size, heap height, acid addition distribution in curing and leaching solution, leach cycles and pad type. Most of the modifications have been implemented after carrying out extensive column test work programs. The modifications implemented and the results obtained, as well as the test work programs carried out, are discussed in this paper.

By James W. Reeves

DuPont was the titanium metal pioneer who put the greatest effort into both R&D and commercial sponge and powder metallurgy production. This was concentrated in the period 1945 through 1963. The commercial results were development of the chloride process for TiCl4 using ilmenite, development and improvement of the Kroll process, development of a modified Hunter process to make titanium powder and commercial development of a direct powder process. The powder metallurgical process failed because of the inability to meet powder chloride specifications. All this work remained a trade secret until published in NMAB -392 by Mahla in 1983. There were other processes explored by DuPont, both improved sponge and powder processes. Much of this work has been continued by others but none, as of yet, resulting in new improved titanium metal capacity.

Jan 1, 2001

By Nagahiro Saito, Takahiro Ishizaki, Mituhito Hirota, Akio Fuwa

"Owing to their extremely high toxicity in the environment, the dioxins have been attracting social, technical and scientific attention in recent years. The authors theoretically had predicted the thermodynamic properties of all the dioxins via quantum chemistry and statistical thermodynamics and elucidated the generation-decomposition behavior of dioxins in the equilibrium calculation· of C-H-0-Cl system. In actual combustion processes, it is said that metallic compounds have much influences on the dioxins behavior. The aim of this study is to reveal the roles of metallic compounds the generation-decomposition behavior of dioxins is revealed from the viewpoints of quantum chemistry. Especially, the catalytic effect of copper has been investigated for the reaction, 2HCl(g)--H2(g}+Cl2(g) and for the etherification reaction from precursors, which is Phenol(g) here, to dioxins. The catalytic role of Cu is shown to have much influence on the generation -decomposition of dioxins.1. IntroductionIt is well known that dioxins are very harmful not only for our health but also for that of our children and grandchildren because they are very stable substance and their reaction rates of decomposition are considerably low. On the other hands, it is not well know how dioxins are generated and decomposed; the generation-decomposition conditions and paths as well as the catalysts to decompose them'1l. The authors believe that the thermodynamic and kinetic study of dioxins is useful to find a solution to these issuers. The authors have been investigating the following problems to reveal the generation-decomposition behavior of dioxins; (a) the prediction of the thermodynamic parameters of dioxins (2), (3), (b) the generation -decomposition behavior of non-chlorinated dioxins by the thermodynamic equilibrium calculations in C-H-O system(4) and (c) the generation-decomposition behavior of dioxins by the thermodynamic equilibrium calculations in C-H-O-CI system(5). Summaries of these thermodynamic researches are as follows.(I) The thermodynamic parameters for dioxins, which had been unknown and/or inaccurate'6 l, could be predicted and are available within the scientific accuracy."

Jan 1, 2000

By Jinxia Nie, Yunnen Chen, Dachao Zhang

"Rare earth resources are strategic and non-renewable resources. But disordered exploitation on rare earth metals leads to resources waste, environmental pollution and ecosystem destroyed. In this paper, soil collected from garden was cultured in thermostated incubator. Adding exogenous rare earth to the soil and the effects of recombination action of rare earth lanthanum, cerium and yttrium on soil enzymatic activities were studied. The results showed that single metal La and Ce can increase urease activity, but Y inhibits its. Coexist La/Y or La/Ce in soil inhibit the urease activity, coexist Y /Ce or coexist three metals promote its. Single metal La, Y and Ce can promote catalase activity, and that of coexist three metals. Pairwise coexist La, Y, Ce in soil inhibit catalase activity. With certain concentration of rare earth recombination action, urease activity in soil has been very significant direct proportion to ionic impulse, but catalase activity been insignificant inverse proportion to its.1. IntroductionThe increase of rare earth element content due to anthropogenic inputs frequently takes place in agro-industrial areas, leading to soil pollution episodes that may cause serious environmental problems because of their potential toxicity to microorganisms, plants, animals and human beings [ 1]. China is abundant in lanthanides resources. Rare earth metals are used in many frontier technologies such as photic devices, magnetic materials, and fine ceramics, and the amount of the rare earth metals used in these industries has been increasing. In addition to their use in industry, rare earth metals are more widely applied to cropland as microelement fertilizers due to their ability to promote growth and productivity of some crops [2]. As a result, more and more rare earth metals are moving into the ecosystems. While a permanent contamination of soils results in populations of micro-organisms with high resistance to rare earth metals, a short-term burden of contaminants at high concentrations could exert inhibitory effects on microbial carbon [3]. They accumulate in soils, bioaccumulate in crops, and enter the food chain, causing a potential problem of rare earth metals environmental pollution in China [4]. This contamination may also severely influence organisms and soil activities [5]."

Jan 1, 2011

By Yuanbo Zhang, Zhixiong You, Guanghui Li, Peidan Wen, Tao Jiang

Sn-bearing iron ore containing small amount of Zn, Pb and As is one of the typical complex polymetallic ores in China. This kind of ore is not extensively utilized due to the complicated relationships between iron and other associated nonferrous metal minerals. Excessive contents of these elements would adversely affect the metallurgical operation as well as the quality of steel products. In this study, reduction behavior of Sn was detailedly investigated using H2 or mixed H2/CO as reductant. The results revealed Sn volatilization was improved in the presence of H2 than individual CO/CO2 atmosphere. Simultaneous volatilization of these elements was realized by roasting under weak H2/CO reducing potential, and metallization reduction was advantageous for further Zn volitilization. A metallic pellet (DRI) with Fe metallization greater than 90%, residual Sn, Zn, Pb and As content of 0.054%, 0.012%, 0.0045% and 0.09% was prepared via a simulated reducing gas of coal gasification.

Jan 1, 2015

By W. G. Davenport

Chapter 11 determined the combinations of industrial oxygen, oil and blast preheat that will steadily produce 65% Cu matte from pure chalcopyrite concentrate. It showed that the . combinations are described by a flat plane. It also showed that the minimum energy requirement for making 65% Cu matte occurs with maximum oxygen enrichment, zero oil and zero blast preheat. This chapter examines the, effect of matte grade on industrial oxygen, oil and preheat requirements.

Jan 1, 2001

By Xin Zhang, Xu Zhang, Hao Bai, Ning Li

Organic Rankine Cycle (ORC) is an effective technology for low-grade waste heat power generation. In this paper, the thermal-dynamic performance of ORC system, in which low-temperature waste heat (from 40-140oC) is used as heat source, was evaluated with software RefProp8.0. The result indicates that in the range of low temperature, the working fluids like R601, R601a, R600a, R141b, R245fa and R245ca have better thermal performance. Furthermore, pilot-scale experiment using R245fa as working fluid was conducted, which validated the operation of the system for low-grade waste heat recovery. Finally, the economic feasibility of ORC has been analyzed for an ORC system using the waste heat from quenching water of blast furnace slag (80oC). According to the analysis, the project is reasonable in economy because the recovery period of investment is less than 4.2 years and environment-friendly since the CO2 emissions can be reduced by almost 43650.68t annually.

Jan 1, 2016

By Kazuhiro Asai

Hitachi Refinery of Nippon Mining & Metals Co., Ltd. installed a reverberatory type recycling fumace in 1978 in order to treat the industrial wastes which contain metal elements such as copper, gold and silver. Pyrite and industrial waste materials such as galvanizing sludge, hydroxide slime and dust are smelted. Sulfidized copper, iron and precious metals are transformed into matte and other metallic elements are oxidized into slag This copper matte is transported to Saganoseki smelter and copper and precious metals in the matte are recovered. Recently it is difficult to obtain pyrite economically because of the decrease of pyrite production. Therefore, a new treating process of the liquid waste has been investigated at Hitachi Refinery. In this process, the sulfide or sulfate from the liquid waste are smelted as a source of sulfur.

Jan 1, 1997

By Lucas Lopes da Costa, Sergio Neves Monteiro, Rômulo Leite Loiola

"Composites with DGEBA/TETA epoxy matrix reinforced with thinner and continuous bamboo fibers stripped from culms were mechanically characterized by tensile tests. Specimens with up to 30% in volume fraction of aligned fibers were tensile ruptured at room temperature. The results showed a steady increase in both the ultimate strength and the elastic modulus of the composites with the amount of incorporated bamboo fibers. The fractographic analysis by scanning electron microscopy showed evidence of moderate adhesion between the bamboo fiber and the epoxy matrix. This fiber/matrix adhesion by interaction mechanism apparently justifies the improved tensile properties of the composites.IntroductionIn recent years polymer composites reinforced with natural fibers, mainly those lignocellulosic obtained from plants, have been subject to extensive research works [1-5]. Environmental, economical, societal and technical advantages of these composites are motivating their substitution for similar polymer composites reinforced with synthetic fibers. In particular, R & D efforts have been conducted aiming to replace glass fibers composites that are comparatively more abrasive to equipments, non-recyclable, more expensive, heavier and toxic [6]. Among the many lignocellulosic fiber composites being investigated, those fabricated with bamboo stripped fibers, i.e., fibers longitudinally cut from the culm, still need information to support possible industrial applications. Several works, however, have been dedicated to bamboo stripped fibers as possible reinforcement of polymer composites [7-17]. These works reported mechanical properties that could markedly vary with the type of polymer matrix, the fiber disposition (if continuous, aligned, short-cut, mat interlayered, etc) and the test condition."

Jan 1, 2011

By Hong Ro Lee, Seang Suk Cho, Byung Sun Chun, Chang Whan Won

"The preparation of Al203-SiC-TiC composite powders was studied by SHS process using silica (source of Si02) powder instead of Si which is expensive. And, aluminum powder was used as reducing agent of silica and charcoal activated was used as carbon source. Effects of the molar ratio in raw material mixtures and compaction pressure and initial temperature of reactant on the products and combustion process were studied. The most important variable affecting the synthesis of Al203-SiC-TiC was the molar ratio of carbon. The combustion reaction generated in powder state without preheating. But the unreactants exist in the product on all molar ratio. When the preheating temperature is over 400 °C, the combustion reaction was able to be generated in pellet state. Without preheating, the combustion reaction was possible by Ti02 addition. The optimum condition in this system was the molar ratio of Si02:Ti02:Al:C=2.5:0.5:4:3.1. INTRODUCTIONCeramics have demonstrated a capability as a cutting tool, especially in competition with WC-Co cermets (ceramic-metal composites) as inserts for metal turning and milling operation. The advantage of ceramics compared with carbides is retention of high hardness, strength, and chemical inertness to temperatures in excess of 1000 ·c . This allows use of the ceramics at much higher machining speeds than can be tolerated by carbides. However, the ceramics have lower toughness than the carbide materials, and have only been used successfully in the limited operations of turning and milling. There are several classes of cutting tools. The addition of TiC or PSZ, or both, and reinforcement with SiC overcame the poor fracture toughness and thermal-shock resistance that limited Al203 use in the past [1]."

Jan 1, 1998

By Xiyun Yang, Hui Xu, Xichang Shi, Xiang Xiao

"Rod-like magnetite particles were prepared by precipitation of iron salts with urea under the induction of magnetic field. Temperature and initial Fe3+/Fe2+ ratio have a significant effect on the composition of the product. Magnetite particles change from spherical into rod shape in the presence of a 0.35 T magnetic field, The addition of a small amount of spherical seeds increases the rod-like magnetite particles yield. The seeds are prepared by aging ferrous and ferric solution with sodium hydroxide as precipitator. The aspect ratio of the rod is controlled by varying the volume ratio of seed to iron salt.IntroductionMagnetite, an important member of magnetic materials, has attracted a lot of attentions for its super magnetic properties. The rod-like magnetite particles have high anisotropy and coercive force as well as super magnetic properties compared to other shapes, and are widely used as high magnetic density media, magnetic devices and microwave materials [1-4]. Recent studies have found that magnetic field can direct magnetite growing along easy magnetization axis to get one-dimension particles [5-6]. Chen et al. [7] synthesized single crystalline nanorod magnetite under magnetic field. Wang et al. [8] discovered that magnetite grew along easy-magnetization directions under 0.35T magnetic field. Vereda et al. [9-1 O] found that magnetic field had a dramatic effect on the morphology, inducing the aggregates to line along one direction to form rodlike particles.At present, most of the synthesis methods reported in the literature result in a low yield of rod particles and the aspect ratio are difficult to control. Recently, we developed a seed-mediated growth approach to making rod-like particles in an aqueous solution. The spherical magnetite generated by oxidation serves as a seed. These seeds are then added to a solution containing iron salt and urea, and provide nucleation sites for magnetite rod growth."

Jan 1, 2011

By Ajay K. Singh

The surface quality demands for galvanized and galvannealed steel sheets by the automotive and appliance industries have been getting increasingly stringent over the past few years. Intensive efforts by Hot-Dip-Galvanizers to meet these demands have resulted in substantial improvement to the hot dip coating process. However, elimination of zinc bath contaminants which directly affect the coated strip surface quality continues to remain a tough challenge. As part of our effort to improve the zinc bath cleanliness, Inland Steel Company has developed a test method to quantitatively measure the contaminants in incoming zinc spelters and establish a specification for incoming zinc quality. The test is currently being used for auditing the incoming zinc quality. The zinc suppliers are also using this test for quality control purposes. The purpose of this paper is to describe the test method and how it has improved the galvanizing operation at Inland.

Jan 1, 1992

By Kenji Sasaki

Tamano Smelter started its operation in January, 1972 adopting FSFE ( Flash Smelting Furnace with Furnace Electrodes ) type smelting furnace at a production capacity of 101,00Ot/y of anode copper and 285,00Ot/y of sulfuric acid. Since then, it had experienced several production expansion program, it had twice as production capacity as start. 196,000t/y of anode copper and 436.000t/y of sulfuric acid. This time, we have completed the plan for increasing production capacity up to 226,000t/y of anode copper and 510,000t/y of sulfuric acid, by the oxygen enriched operation. We carried out several improvements and modifications, changing of cooling system ill FSFE, enlargement of converter and anode furnace, and some progresses in sulfuric acid plant and environmental facilities.

Jan 1, 1993

By Jeffrey W. Braithwaite

The laboratory characterization of the oxidation of chalcopyrite under conditions of deep solution mining is presented in this paper. A salient feature of this system is the pH buffering effect resulting from simultaneous acid producing and acid consuming oxidation reactions. The solution chemistry and related sulfur partitioning of the oxidation reactions are detailed. The contribution of temperature, acid concentration, oxygen pressure, particle size, and solution additions to the kinetics of copper extraction are presented. A mixed kinetic model was used to describe the kinetics of oxidation.

Jan 1, 1976

By Kazuyuki Kakegawa

The sintering characteristics and the change in the compositional distribution in the PbTiO3-PbZrO3-Pb(Mg1/3Nb2/3)O3) system during the sintering process by spark plasma sintering (SPS) method were examined. They were compared with those by a normal sintering method. The densifieation by the normal sintering was slow even at high temperatures. When SPS method was employed, much lower temperature and shorter period resulted in sintered bodies having almost the theoretical density. As expected in normal sintering, the compositional distribution decreased as the sintered density increased. On the contrary, the change in the compositional distribution by SPS was much smaller than that in the normal sintering. This sintering characteristic of SPS suggested a possibility of fabrication of sintered material having a desired compositional distribution.

Jan 1, 2003