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By Chu Yong Cheng

The solvent extraction (SX) processes of the three pressure acid leach (PAL) nickel plants in Western Australia have been reviewed. The use of intermediate precipitation, solids/liquid separation and re-leach in the three W A nickel plants make these processes complicated and costly in capital and ?operation. The research work carried out by the SX group at the AJ Parker Cooperative Research Centre for Hydrometallurgy I CSIRO Minerals has led to the development of direct solvent extraction (DSX) processes to recover and purify nickel and cobalt from leach solutions. The simplicity of the process flowsheets and the expected savings in capital and operating costs are the major advantages of the new DSX processes over the reviewed processes. By using a new synergistic organic system in semi-continuous tests with a pilot plant leach solution (after iron precipitation) from BHP-BiIliton Stainless Steel Materials, the metal values (Ni and Co) together with zinc and copper were separated from the major impurities (Mn, Mg and Ca, together with Cl) in the first SX circuit. The co-extracted manganese, magnesium and' calcium were easily scrubbed out. After stripping, the metal values (Ni and Co) together with zinc and copper were concentrated, resulting in a much smaller second SX circuit and equipment in the down stream processes. The extraction and stripping kinetics of the metals with the new synergistic organic solution were very fast. The extraction and stripping almost reached steady state within 0.5 minutes. Semi-continuous test work with a synthetic leach solution, a cobalt pilot plant leach solution from Peko Rehabilitation Project Pty Ltd and a synthetic solution to simulate a concentrated laterite leach solution from BHP-Billiton Stainless Steel Materials showed that manganese, calcium, copper and zinc can be effectively and efficiently separated from nickel, cobalt and magnesium by extraction, scrubbing and stripping. This led to the development of another DSX process using D2EHPA to recover nickel and cobalt from leach solutions.

Jan 1, 2003

By J. B. Vander Sande, I. G. Solórzano, B. S. You, P. M. Jardim, W. W. Park

"Alloys with six different compositions in the system Mg-Ca-Zn were produced by melt spinning. The aging behavior of alloys was investigated by measuring the changes in microhardness after isochronal aging and the microstructure was analyzed by means of transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDS), scanning transmission electron microscopy (STEM) and scanning electron microscopy (SEM). All six compositions in the as-solidified condition show a difference in microstructure between the wheel contact side (zone A) and the free surface side (zone B) as a result of the differences in the solidification rate across the ribbons. One of the alloys (Mg-l.5wt%Ca-6wt%Zn) was chosen to be more deeply investigated in this work as it exhibited grain boundary films and an age hardening behavior was produced in that alloy.IntroductionMagnesium is the lightest of all the commonly used metals, and very attractive for applications in transportation. It also has a number of other desirable features, including good ductility, better damping characteristics than aluminum, and excellent castability. However, there are some negative features, such as high reactivity in the molten state, inferior fatigue and creep resistance as compared to aluminum, poor corrosion resistance and high production cost.In recent years there has been a significant increase in magnesium use as a structural material. These structural applications include aerospace, automotive and nuclear industries as well as appliances and sporting goods (1 ). According to reports on Mg-Zn alloys, the addition of Zn (2) in magnesium increased strength. Also, since the maximum solubility of Zn in magnesium is 6.2wt%, a considerable amount of Zn can be retained in solid solution in magnesium alloys by rapid solidification. In addition, Ca is known (3) to be one of the most potent alloying elements for refining the microstructure and precipitates in magnesium alloys, and also to improve mechanical strength and corrosion resistance."

Jan 1, 2000

By Cindy L. Williams

"The Blue Star subdistrict in the Carlin Trend, Nevada, includes multiple mines with 33.9 t Au in reserve and past production totaling 89 .1 t Au. The deposits are characterized by zoned alteration mineralogy and gold grades. From orebody centers outward the zones include: 1) a silicified core with erratic gold grade; 2) adjacent mill-grade (> 1.37 Au git) intense quartz-sericite-pyrite alteration; 3) enveloping leach-grade (0.21 Au g/t to 1.37 Au git) weaker sericite-kaolinite-quartzpyrite alteration; 4) surrounding decarbonatized and intensely argillized waste and leach grade ore; 5) pervasively decarbonatized waste rock; and 6) peripheral waste with weak decarbonatization and local propylitic alteration. Zoned alteration extends as much as 1500 m beyond orebodies.Understanding Blue Star subdistrict zoned alteration assemblages and gold grades has increased geologists' ability to provide practical and economically significant information to geotechnical engineers, mine planners and drill and blast personnel. Alteration influences geotechnical pitslope design because each assemblage has distinct rock strength. Geotechnical engineers use three-dimensional models of incompetent alteration types as a foundation for pit-slope design. In the drill and blast cycle, hard and soft alteration types require modified practices (powder column, blast hole spacing, delay design etc.) for optimum blast energy distribution. Further, geotechnically instable alteration types require careful blast procedures to prevent backbreak whic~ damages ultimate walls. In addition to mine planning and mining applications, zoned alteration assemblages extending beyond orebodies provide a useful exploration guide. Metallurgical character also varies with alteration type. Intensely quartz-sericite-pyrite altered or silicified ore has relatively high partical-size dependency and poor leach recoveries. Moderately sericite-kaolinite-quartz-pyrite altered rock, in contrast, shows little size dependency and good leach recoveries.The author sincerely thanks L. Schutz, P. Williams, C. Clode, W. Trudell, P. Herrera, M.DKunkel, M. Goings and numerous other Newmont geologists, metallurgist, engineers and support staff who made this paper possible."

Jan 1, 1997

By Felipe P. D. Lopes, Jr. dos Santos, Sergio N. Monteiro, Frederico M. Margem

"Natural fibers are gaining attention as a class of low cost, biodegradable and renewable materials that also exhibit some interesting properties for specific applications. In particular, the incorporation of some natural fibers in polymeric matrix composites is nowadays providing opportunity of manufacturing a variety of industrial items, for instance automobile interior components. Among these fibers, ramie (Boehmeria nivea) is one of the least investigated and only recently was studied as polymeric composite reinforcement. Therefore, the objective of this work was to evaluate the possibility of ramie waste reinforced polyester composites to replace conventional building materials, such as plywood, plastic boards and gypsum panels in terms of a cost-benefit analysis.IntroductionThere is a growing concern over the environmental questions that are presently affecting our society in a global sale such as climate changes and generalized pollution. Among the solutions for these questions, the replacement of energy intensive materials, especially those long term degradable such as the synthetic fibers, is already being considered [1]. As a consequence, the past decades have witnessed an increase in research devoted to new biodegradable materials obtained from natural resources mainly the biomass. Important examples are the renewable natural fibers as well as composites incorporated with them [2,3]. In addition to their friendly status with respect to the environment, well know natural fibers like jute, sisal, wood, coir, hemp and flax are relatively low cost and recyclable. In recent works [4,5], the use of these cultivated and abundant lignocellulosic fibers was investigated as the reinforcement phase in polymeric composites.Other less know lignocellulosic fibers have also been recently investigated [6,7]. These are fibers that likewise show a potential of incorporation into the polymeric matrix of composite materials. Most of these less know fibers are typical of tropical regions and, in principle, their application in industrialized composites would represent job opportunities for developing countries in Africa, South Asia and Latin America."

Jan 1, 2008

By Ludy C. Motta, Denise C. O. Nascimento, Sergio N. Monteiro

"Natural cellulose-based fibers are nowadays of growing interest for modern industrial composites. Relatively unknown fibers like piassava, curaua and gourde have shown promising behavior as reinforcement of polymeric composites. However, the hydrophilic characteristics of the natural fibers impair its adhesion to the normally hydrophobic polymeric matrix. Surface treatments can, in principle, improve this adhesion and the fiber/matrix interfacial strength. In this paper, the effect of alkali treatment of the surface of piassava (Atallea funifera) waste fibers was investigated in terms of the change in strength of epoxy composites reinforced with these waste fibers.IntroductionThe consequences of global warming and the increase in the price of petroleum are motivating the use of natural materials as substitute for energy intensive synthetic materials [1]. In particular, natural fibers obtained both, from cultivated plants such as jute, sisal, hemp and flax as well as from industrial waste such as sugar come bagasse and coir, are being considered to replace synthetic glass fibers [2,3]. These natural fibers, also known as lignocellulosic fibers, present the comparative advantages of being renewable, recyclable and biodegradable. Moreover, lignocellulosic fibers require less amount of processing energy and are neutral with respect to CO2 emission, which causes the atmospheric greenhouse effect responsible for the global warming [4]. Low cost is another important economical advantage of the natural fibers over the synthetic ones and the application of lignocellulosic is also associated with a lower wear of processing equipment and better finishing of molded components [5]. Moreover, for some fibers, properties such as the mechanical strength and impact resistance can be superiors to the corresponding properties of synthetic glass fiber [6]. The characteristics and properties of several lignocellulosic fibers are, nowadays being extensively discussed in the literature. It is beyond the scope of this work to comment on the hundreds of papers dealing with this subject. However, there are still less known fibers with great potential as engineering material that deserves investigation."

Jan 1, 2008

By Wander. L. Vasconcelos, Virgínia. S. T. Ciminelli, Angela. M. F. Guimarães

"The present work was aimed at synthesizing nanostructured hybrid materials derived from the functionalization of smectite clays with ligands containing thiol (-SH) groups for application in cadmium adsorption processes. An in nature Brazilian bentonite was investigated. The modification route was based on the grafting reaction between hydroxyl groups present on clay surface and the hydrolyzable alkoxy group of the (3-mercaptopropyl)trimethoxysilane in dry toluene under reflux. The present work showed that the proposed modification route was effective for the grafting of the thiol groups in the clay structure. The thiol-functionalized bentonite samples showed average binding capacities 160% higher with respect to Cd2+ to those obtained with the ungrafted material. These results support a mechanism of adsorption involving primarily ion complexation by the thiol groups (specific) instead of cation exchange (unspecific). The proposed modification processes are suggested for the preparation of novel adsorbent materials with controlled selectivity and specificity and therefore with good potential for separation and pre-concentration purposes.IntroductionMany efforts have recently been devoted to the design and preparation of inorganic-organic nanomaterials because of their potential application in novel functional materials. The intercalation of organic species within the spaces between interlayers of inorganic layered crystals provides nanostructures consisting of alternating layers of inorganic and organic compound. The intercalation reactions occur by insertion of mobile guest species (neutral, molecules, or ions) into the accessible crystallographic-defined vacant sites located between the layers (interlayer spacing) of the layered host structure [1}.Silane coupling agents, used widely for the modification of silica surfaces, have also been employed more recently for modification of layered silicates [2,3,4,5]. Modification with organosilane involves grafting reactions by establishing covalent bonds between the reactive groups of the layer, normally hydroxyl groups, and silane molecules. These reactions can be restricted to the external surface (the basal spacing remains unchanged) or to the interlayer surface, in which case an interlayer expansion occurs. The resulting material can be defined as a hybrid material or, more specifically, functionalized inorganic layered material [1]."

Jan 1, 2008

By Michal Rzyman, Nakamura Takashi, Shibata Etsuro, Grabda Mariusz, Oleszek-Kudlak Sylwia

"Thermodynamic considerations indicate that heavy metal oxides should easily react with HBr, the main gaseous product from the thermal decomposition of tetrabromobisphenol A (TBBPA), forming low boiling point metallic bromides suitable for volatile separation. Mechanisms and kinetics of the bromination reactions must be well recognized prior to developing of a new treatment for the simultaneous recycling of plastic waste containing brominated flame retardants (BFRs) and metal oxides (printed circuit boards, automotive shredder residue, plating sludge, metallurgical dusts). In this work, a differential scanning calorimeter and laboratory-scale furnace were used to investigate the possibility and conditions of the bromination of ZnO by product of thermal decomposition of TBBPA. The formed solid, condensed and gaseous products were analyzed by X-ray diffraction analysis, electron probe microanalysis, inductively coupled plasma analysis, ion chromatography and gas chromatography coupled with mass spectrometry. Introduction Tetrabromobisphenol A (TBBPA) is the largest volume brominated flame retardant (BFR) in production today and is used in more than 70% of the world’s electronic and electric (E&E) appliances [1]. The growth in the production of E&E products and the fact they become obsolete so quickly cause significant problems in the safe disposal and recycling of the electrical and electric waste (E-waste) and other BFR-containing waste [2]. Among various treatment processes, thermal methods are most useful since they allow the recycling and recovery of both the organic and inorganic fractions of the waste. However, incineration of the BFR-containing wastes results in the emission of hazardous organobromine compounds, while the main portion of bromine released from decomposed BFRs is present in flue gas as hydrogen bromide (HBr) [3]. HBr, which is known to damage incineration systems, seems to be a very effective bromination agent for many metallic oxides present in waste. The concept of this study is to take advantage this of its property."

Jan 1, 2008

By Tetsuya Uda, Sakae Shirayama

"With the aim of producing nickel (Ni) metal directly from acidic aqueous solution containing cobalt (Co) and other impurities, selective reduction of Ni was examined. As a preliminary experiment, sodium hypophosphite monohydrate (NaH2PO2·H2O) was selected as a reductant, and reacted with aqueous solution containing 0.1 mol L-1 nickel sulfate (NiSO4·6H2O) and 0 ~ 0.05 mol L-1 cobalt sulfate (CoSO4·7H2O) for 3 hours at 90 °C. As a result, it was revealed that Ni was selectively reduced and separated from Co in the acidic region (pH= 4.8). In this study, differences of reduction behavior between Ni and Co were investigated, and the feasibility of Ni I Co separation by the selective reduction of Ni was discussed.IntroductionEfficient Ni condensation and separation from Co are essential in nickel hydrometallurgical processes. Currently, the hydrometallurgical production of Ni from oxide ore is mainly carried out by acid leaching at elevated temperature, followed by the removal of impurities using neutralization, and condensation of Ni and Co into intermediate products such as hydroxides and sulfides. Then, the intermediate product is dissolved in acid aqueous solutions, and Ni I Co separation is conducted by solvent extraction. Finally, Ni and Co are recovered by electro-winning. This complicated process consumes large amounts of alkali, hydrogen sulfide (H2S), and organic solution in a multiple-staged process'. To reduce the consumption of these chemicals, it is important to recover Ni more efficiently from acidic aqueous solution containing impurities."

Jan 1, 2014

By Jian Pan, Zhen He, Deqing Zhu, Shouyan Yue

"The differences of raw material characteristic among six kind of iron concentrates and the influences on ballability were studied from the aspect of the size distribution, specific surface area and particles morphology. The results show that the specific surface area of iron concentrates has crucial influence on ballability, and the effective method of improving ballability for weak ballability iron concentrate has been found. It is of important guidance for Chinese steel mills to import and use iron concentrate from the whole world.IntroductionChina's steel industry has developed rapidly in recent years, crude steel production in 2011 is an unprecedented 683 million tons, which is almost half of the world crude steel production, and it is equivalent to the total sum production of the nations which rank at 2,3,4,5 and 6 in the world [1]. In order to match the development of steel industry, the blast furnaces are becoming larger and more modernization, therefore charging burden of higher quality is requested, and the reasonable blast furnace burden structure is more and more important, at the same time, for iron ore powder sintering process's continuous improvement and development, another method providing ""concentrate"" for blast fumace-pelletizing is also taken seriously. The grate-kiln method of pelletizing has achieved great development for its unique advantage, and in just a few years, there are over 60 rotary kiln production lines have built or being built in China, the sum of pellets has reached to more than 140 million [2, 3]. The rapidly growth of pelletizing yield demands diverse source of pellet, which include not only domestic magnetite concentrate, but also imported hematite which is high in iron and low in silicon. Usually the ratio of imported hematite concentrate increased gradually. The imported hematite concentrate has high grade and fine particle size (the content of -0.074 mm mostly higher than 90%), but the ballability of part of the concentrates is poor."

Jan 1, 2013

By Guodong Lai, Shixing Wang, Lijuan Chu, Jinhui Peng, Zebiao Zhang

"The beneficiation of poor manganese ores containing phosphate gangue is very difficult by conventional processes, because of the similarities in the physico-chemical properties of the constituent minerals. The shaking table gravity concentration process and concentrated strong acid selective intensified leaching process were used for dephosphorisation of Yunnan manganese ore. The leaching process was effective. The effects of intensified leaching time, solid-liquid ratio and particle size were investigated. The relevant leaching factors were optimized as -0.125+0.088 mm particle size with 68% nitric acid for 24 h when using a solid-liquid ratio of 1:1 at room temperature and atmospheric pressure. Under these conditions, the P/Mn ratio was reduced from 0.0107 to 0.0056, and the grade of manganese was increased from 12.32% to 42.76%. The dissolution of manganese during leaching was negligible.IntroductionManganese and its compounds are widely used in the iron and steel industry as deoxidation and desulfurization agents and as alloying additives [1-2]. Because of the increase in demand, low grade refractory manganese ores are becoming a new source. Many Chinese manganese ores are high in phosphorus, which cannot be used directly for metallurgical purposes. This occurs because phosphorus enters into the metal phase during smelting and its presence sharply deteriorates the mechanical properties of the metal [3-4].Kanungo and Sant [3] investigated the dephosphorization of phosphorus-rich manganese ores by selective leaching with dilute hydrochloric acid. They observed that leaching with dilute hydrochloric acid (0.1-0.6M) could reduce the phosphorus contents to the specified limit of 0.12%. Ye [5] investigated dephosphorization of high-phosphorus manganese ore of the Huayuan type. Using high intensity magnetic separation, roasting and leaching with acid for dephosphorization, as used in the industry, a 40.15% manganese concentrate with a P/Mn ratio of 0.0037 was obtained. Yimin [6] investigated magnetic separation followed by inverse flotation of high-phosphorus manganese ore, and found that the P/Mn ratio could be reduced from 0.046 to 0.002."

Jan 1, 2012

By Kunio Nakahara, Kashiwagim Junichi, Takao Hayashi

"There are many problems for electronic devices and parts which were caused electrostatic damage by static electricity. It is necessary for prevention of electrostatic charge to decrease surface resistivity of material using electroconductive coating. Mitsui Mining & Smelting Co., Ltd. developed metal oxide type electroconductive pigment PASSTRAN (trade mark) Type-IV which is barium sulfate coated with SnOz(Sb) thin electroconductive layer. This paper shows about pigment characteristics and film condition of antistatic transparency paint which contained PASS TRAN.L.IntroductionRecently rapid development of electronics technology diffused electronic devices and products to Office, Factory, Laboratory and our life. But the other side, there are many problems for electronics parts which were caused electrostatic damage under static electricity. Demand of antistatic materials were become lager by this situation.There is close relationship between surface resistivity of material and static electricity. If the surface resistivity of object is enough low (under 109 Q /Sq), static electricity is dissipated quickly. So it is necessary for prevention of electrostatic charge to decrease surface resistivity of material using electroconductive coating.1) There are many type of electroconductive materials, for example, carbon black, metal powder, electroconductive polymer and so on. Especially, carbon black is used for general purpose by reason of its low cost, but it has big problem of black color. It can not get any color without black, and it caused contamination of carbon.In recent years, metal oxide electroconductive pigment (ECP) was developed and used for special purpose which demands transparent coating or easy dispersion to make ECP paint or endurance under hard environment and so on. Mitsui Mining & Smelting Co., Ltd. developed electroconductive pigment PASSTRAN Type-IV which is BaS04 coated with electro-conductive Tin oxide layer."

Jan 1, 1998

By Zhong Juya, Wang Yong, Guo Xueyi, Song Yu, Tian qinghua

"In this work, the flow of zinc in China, 2004, was traced within the STAF model, and the situation of production, consumption and recycling of zinc resources in China were introduced. The SFA is performed on zinc flows during its one year life cycle in detail. The result reveals that China produces and utilizes a large amount of zinc, while the efficiency of renewable zinc resources is still relatively lower. As one of the biggest producer and consumer of zinc in the world, China is facing a severe depletion of zinc resources. How to increase the resource efficiency is a significant issue for zinc industry of China. Based on the result, several advices were proposed in the paper, aiming to contribute important reference information for the industrial metabolism and resource management and recycling of zinc industry in China. IntroductionZinc is one of the important metals in national economic development in China; it has good conductivity and corrosion resistance, with high scalability when heated to 100 ~105_. Zinc is mainly used for galvanized zinc industry, as the coating of steel and various parts, and it has also been applied to the manufacture of brass, bronze and corrosion-resistant alloys, which are widely used in machinery manufacturing, printing, national defense and so on. In addition, zinc compounds are utilized in various fields, for example, ZnO is used for infiltration wood, paper, rubber, paints, etc.; ZnSO4 for leather, ceramics, textiles, medicine, etc.; ZnCl2 for infiltration wood; ZnS2O4 and Zn (HSO2 • CH2O) 2 for the paper and textile bleaching, etc. [1]. The extensive use and consumption of zinc in industrial production and social life promot the rapid development of zinc industry, which made zinc the third largest non-ferrous metals in the world."

Jan 1, 2008

By Orion Ciftja, Arjan Ciftja

"The directional solidification method is routinely used to produce polycrystalline silicon, an important material for the photovoltaic (PV) industry. The form of the solid-liquid interface during solidification has considerable influence on the material quality. The dissolved impurities and the solid inclusions above the solidification front affect the interface and may cause interface breakdown. We investigate the effects of pushing and engulfment of silicon carbide (SiC) particles by the solidification front during directional solidification of silicon. We employ a 12kg directional-crystallization furnace to cast the molten silicon. We use upgraded metallurgical grade silicon with low concentrations of metallic impurities (< 5ppm) and a high content of carbon (700 ppm) present as SiC particles. Samples from the cast polycrystalline silicon ingots are investigated by light microscope. The expected interaction of impurities with the solidification front is investigated theoretically using empirical models. The data obtained from the models are in good agreement with the experimental results.IntroductionDirectional solidification is a well-known method for producing multi-crystalline silicon for the PV industry. In this method a planar front, achieved during solidification, results in a clearly defined interface between the solid and the liquid phase. The solubility of major impurities is higher in the liquid than in the solid phase. Therefore, directional solidification will work as a purification process where the impurities are retained in the liquid phase [1]. Apart from the process of removing the dissolved elements in molten silicon, the directional solidification plays also another role. It will interact with the solid particles that may be present in the melt. When a liquid containing an insoluble particle is solidified, three distinct interaction phenomena are observed: engulfment of particles, continuous pushing, and entrapment [2]. The term “engulfment” is used to describe incorporation of a particle by a planar interface, and the term “entrapment” is used for particle incorporation by a cellular or dendritic interface (see Figure 1) [3]."

Jan 1, 2014

By Yan Fu, Chuanlin Fan, Xiujing Zhai, Yongfeng Chang, Binchuan Li

"The mechanism of the selective chlorination of nickel and cobalt in reduced limonitic laterite was investigated. Reduced ores were obtained from the reduction roasting of a limonitic nickel laterite. The thermal decomposition of related chlorides and the selective chlorination of the reduced ore were carefully studied using Differential Thermal analysis - Thermogravimetry (DTA-TG), X-Ray Diffraction and chemical leaching methods. In the temperature range of 300 - 500 °C, aluminum chloride hexahydrate was chosen as chloride agent. During the selective chlorination, reduced ore was partly chlorinated by hydrogen chloride generated from the thermal decomposition of chloride agent. Then the oxydrolysis of ferrous chloride re-generated hydrogen chloride was used to further the chlorination. Finally, iron was mostly rejected as hematite, while nickel and cobalt were selectively chlorinated. More than 91 %Ni , 90%Co and about 4%Fe in the chlorinated ore was extracted using a water leaching method.IntroductionLimonitic nickel laterite is an important nickel reserve, which is rich in iron in the form of goethite and has low contents of magnesium, aluminum, silicon, and other elements. Goethite is the main nickel-bearing mineral in the laterite [1]. Nickel is generally present in goethite in three modes: (a) associated with amorphous or poorly crystalline goethite, (b) weakly adsorbed to the crystalline goethite surface, and ( c) as lattice substituents [2]. In addition, cobalt in limonite was found to be associated with a manganese phase rich also in nickel [3]. These results indicate that the extractions of nickel and cobalt are highly dependent upon the degree of the decomposition of the nickel, cobalt-bearing minerals.For the selective extraction of nickel and cobalt from limonitic laterite, the ore is usually processed by hydrometallurgical methods, including high pressure acid leaching (HPAL) [4] or reductive roasting - ammonia leaching (Caron process). However, there are still some disadvantages in these processes, such as the expense of autoclaves and scaling problems in HP AL [ 4, 5], and relatively low overall metal recovery, large energy and reagent requirements for the Caron process."

Jan 1, 2011

By T. T. Chen

Secondary copper anodes are generally rich in Sn, Pb, Ni and Sb, but are notably deficient in Se, Te and Ag. In the secondary copper anodes, most of the Ni, virtually all of the Ag, slightly more than one-fifth of the Pb, about one-third of the As and Sb, and approximately one-tenth of the Sn are in solid solution in the copper. The remaining impurity contents occur as 1-5 µm grain-boundary inclusions in the anodes, and these are mainly Cu2O, SnO2, Cu-Pb-As-Sb-Bi oxide, Pb-Sb oxide, Sn-Ni-Zn oxide, Cu-Sn-Ni oxide, Cu-Sb-Ni oxide (Kupferglimmer) and trace Cu2(Se,Te). Barium sulphate, which originates from the mold wash used in casting, is also present in the anodes. During electrorefining, the BaSO4, SnO2, Pb-Sb oxide, Sn-Ni-Zn oxide, Cu-Sn-Ni oxide and Cu- Sb-Ni oxide inclusions are liberated and accumulate in the slimes layer. Solid solution Ni dissolves and the Ni accumulates in the electrolyte. Solid solution Sn and Pb dissolve, but partly reprecipitate as Sn arsenate and PbSO4, respectively. Solid solution Ag dissolves but rapidly reacts to form Ag2(Se,Te), Ag powder, Ag-bearing Cu2O, (Cu,Ag)SO4 or a complex oxidate phase. Partial dissolution of the Cu-Pb-As-Sb-Bi oxide particles takes place; the Pb component is converted to PbSO4, whereas Cu, As, Sb and Bi dissolve. The reacted particles retain the morphology of the original Cu-Pb-As- Sb-Bi oxide phase. Some of the solubilized As, Sb and Bi remains in solution, but much reprecipitates as SbAsO4, As-Sb-Bi oxide, and as a poorly defined oxidate phase which consists mostly of Cu-Ag-Pb arsenate-sulphate. The high Sn contents of secondary copper anodes do not seem to affect the behaviour of the anodes during electrorefining.

Jan 1, 1999

By Takamasa Ishigaki, Gervais Soucy, Mohamed Rahmane

"The induction plasma jets employed for the in-flight nitridation of molybdenum disilicide (MoSi2) powders were investigated in terms of their flow characteristics. The present study shows the effect of the operating parameters of the plasma torch, as used for this process, on the plasma jet properties. The enthalpy probe techniques, along with mass spectrometry, were employed for the measurement of the jet temperature, velocity and concentration fields. The measured values were compared to the results of a numerical simulation performed on the plasma flowing inside the torch-reactor system. The process operating conditions studied were the plasma plate power, chamber pressure and sheath gas composition. The optimal conditions for effecting the nitridation process using thermal plasma are obtained at moderate plasma plate power, at around atmospheric pressure and by using a mixture of argon and nitrogen as the plasma torch sheath gas.IntroductionMolybdenum disilicide (MoSi2) based composites are considered to be one of the most promising candidates for high temperature structural material applications [!], especially because of their high melting points, good oxidation resistance and relatively low cost. However, the wide application of these composite materials is still limited by some factors such as their brittleness at room temperature and lower strength at high temperature (> 1500 K). To overcome such limitations, a number of researchers [2-4] have earlier studied various kinds of reinforcements for MoSi2, e.g. oxides, silicides and nitrides. More recently, Fan and coworkers [5-9] have demonstrated the possibility of in-flight nitridation and carburization of MoSi2, using a thermal plasma process. This work has confirmed the plasma synthesis route as one of the most promising methods for creating an in-situ second phase structure. Properties of the plasma flow, such as its temperature, flow velocity and composition, are of crucial importance for the nitridation of MoSi2 powders during their flight in the plasma. Therefore, the optimization of such a process involving plasma· generated reactive species necessitates a thorough understanding of the plasma flow characteristics."

Jan 1, 2000

By Caisa Samuelsson, Sina Mostaghel, Theo Lehner

"Rönnskär smelter of Boliden Mineral AB, Sweden, is well known for recycling of base and precious metals. Slag from the electrical furnace is processed at the fuming plant to produce zinc clinker. The granulated slag is a by-product used as e.g. construction material. In this paper, influences of Al2O3 on mineralogy of the slag, which can affect its chemical and physical properties, are investigated. Different mixtures of Al2O3/fumed slag were prepared. Re-melting was carried out in a Thermo-Gravimetry (TG) furnace with an inert atmosphere. Scanning electron microscopy (SEM) and X-ray diffractometer (XRD) were then applied for the analyses. Investigations depict that addition of alumina to slag, results in an increase in the number of spinels and a transformation from iron rich to aluminum rich spinels. Anorthite (CaAl2Si2O8) will also be formed.IntroductionRönnskär smelter of Boliden Mineral AB is located in north of Sweden; the main products of this smelter are: Copper, Zinc clinker, Lead, Gold, and Silver, while sulphuric acid, liquid sulphuric dioxide, and Iron sand are some of the by-products. Reducing the energy consumption and decreasing the usage of finite natural resources are becoming more and more important for the Rönnskär smelter; this result in use of different recycling and scrap materials. Metal residues, from brass foundries, steel mills, and electronic scrap are recycled at Rönnskär smelter [1]. Most of the electronic scraps contain mixtures of various metals together with plastics and ceramics, which can affect the composition and properties of the slag considerably [2]. At the same time, treatment of slag and controlling its composition and properties are of much interest for Base Metals producers from different aspects. Composition of slag influences the physical properties such as: 1) Liquidus temperature [3-4] 2) Viscosity, which controls separation of valuable metals, especially copper by gravity separation [2] and also heat and mass transfer [5] 3) Electrical conductivity [6]."

Jan 1, 2008

By Fatbardha Osmani, Skender Osmani

"A system analysis of the resource and environment management (water, energy etc) starts from its definition. Unfortunately, there is not a unique semantics of the mentioned concept. On these circumstances, in this paper the following issues are presented: 1.A short view on the existing concepts of management. 2.A new definition on the concept of management. It is considered as a complex and rational activity on human and natural resources ,environment etc, which starts from a analysis of infrastructure ,technology , etc, mission , alternatives , project etc. and ends to an optimal output. Basing on this definition, the management has two principal components: strategy and policy. The strategy is referred as a blue print program (the same definition as in Game Theory), which contains all the contingency alternatives. , while the policy is referred as a strategy applied into practice. The strategy is the first , while the policy is the second one. The best alternative of a policy is the project, Each strategy has one and only one project. The mentioned definition erases the differences between concept of policy and politics. Each strategy has its alternatives ,the next has its sub strategy and so on, i.e. whatever are going to be the strategy, there are a hierarchy composed by sub strategies up to the simplest strategies applied by a single individual (human beings or robots). The strategy objectives are necessary and sufficient conditions for its realization i.e . the strategy is an optimal activity, in which all resources are integrated and processed . Several strategies could be joined into one( for example the surface water strategies of the Balkan countries) . In this view, the strategy could be globalized into optimal way basing on different criteria’s as social, economic, environmental, their risks and effectiveness etc. etc An example from the water management illustrates the mentioned concepts."

Jan 1, 2008

By S. K. Varma, Miriam Regalado, Daniel Salas, Erica Corral, Erika Esquivel

"Age hardenable 2014 aluminum alloys and composites containing 0.10 and 0.15 volume fractions of alumina particles (VFAP) have been solutionized at 540 and 550°C for up to 20 hours. The solutionized samples, heat treated for 5 and 20 hours, have been subjected to room temperature rolling until cracking develops. The work hardening curves have been compared to determine the effect of solutionizing time on the rolling characteristics from both hardness and the microstructural evolution points of view. Solutionizing at two different temperatures results in differences in the extent to which the composites can be rolled until fracture. The microstructural characterization by TEM has been performed to understand the room temperature rolling behavior.IntroductionThe effect of solutionizing on the age hardening response of 6061 and 2014 aluminum alloys and composites reinforced with 0.10, 0.15 and 0.20 volume fractions of alumina particles (VFAP) have been reported in the literature [1-4]. A comparison of the monolith and composites indicates that particles promote the aging process through differences in the microstructures in solutionized condition. The first effect of solutionizing is to produce a grain growth process which follows a grain growth law (square of grain diameter as a function of solutionizing time). It appears that it is possible for vacancies to be emitted during grain growth period as they try to minimize the total grain boundary surface area by increasing their diameter. This may be common to both the monolith and the composites. However, the second effect must be exclusively considered for the composites. The particles generate dislocations during the solutionizing process due to the differences in the values of the coefficient of thermal expansion (CTE) between the particles and aluminum base metal. It has been determined [1] that the dislocation density increases with increase in solutionizing time in the composites of 6061 aluminum alloys reinforced with 0.10, 0.15 and 0.20 VFAP. The improved bonding between particles and matrix can give rise to additional generation of dislocations due to curvature effects [1] with the result that the dislocation density continues to increase with increase in solutionizing time even after the CTE effect is considered to have been stabilized."

Jan 1, 1998

By B. G. Thomas

"Mathematical process models can be applied in several different ways to serve industry by inducing beneficial changes to process operation. This paper attempts to summarize the different uses, types, and attributes of these models, and to offer some ideas to consider when developing, using, and reporting on them. Process models range from empirical to mechanistic in nature and vary in complexity from simple analytical solutions to coupled, 3-D transient numerical simulations. They are classified here according to the way in which they are implemented in practice, viz. fully-online models, semi-online models, off-line models, and literature models. The purpose of the model should dictate how choices are made during its development. Ways to validate and compare the model with experiments are suggested. Examples are taken in the context of the author's experience in modeling the continuous casting of steel.IntroductionThe objective of this paper is to provide a partial introduction for this symposium by discussing some basic aspects of the application of mathematical process models in industry. Essentially, the aim is to explore how process models are used to benefit industry, and to offer some general comments and suggestions, based on the experience of the author, on how models can best meet this goal.This work is concerned with process models, which consist of systems of mathematical equations and constants that are solved on a computer to make quantitative predictions about some aspect(s) of the process. The specific variables required as input data and generated as output data are important features of the model. The equations often derive from a numerical solution to one or more differential equations and their boundary conditions. The model also includes the constants, which represent material properties, empirical relationships, and other knowledge about the process, and usually require considerable effort to obtain. Thus, general purpose commercial software packages, (ie. finite-element or finite-difference based codes), are not models in this context. They are useful tools, however, serving as frameworks for the development of process models."

Jan 1, 1994