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By Nils Eivind Kamfjord, Mari K. Næss, Halvard Tveit, Edin H. Myrhaug

"As a part of the FUME research programme being done by the Norwegian Ferroalloy Research Association (FFF), the SINTEF Group and NTNU, several measurements towards quantifying the gaseous and solid emissions from the draining of the silicon furnaces for metal have been carried out.Based on the measured size distribution of the formed fume particles and known particle growth theory, an estimate of the growth time for the given particles has been calculated. The formation time for the measured NO amount has also been calculated based on the fume measurements and a thermodynamic model of the furnace gases combusting with air. The two “formation” times are in the same order of magnitude and they are therefore used as parameters in a CFD model, modelling that the formed fume particles are heating up the surrounding air and thereby forming NO according to the Zeldovich mechanism. The measurements show an approximately equal constant NO formation per fume particle. The CFD model shows results in the same order of magnitude, supporting that the particle growth and NO formation happen under near stoichiometric conditions and are controlled by the formation of SiO2 fume.IntroductionNOx is the common notion for the two gases nitric oxide (NO) and nitrogen dioxide (NO2) formed during combustion of fuels. The main sources for human made NOx emissions is on-/offshore transportation industry, power generations based on fossil fuels, agriculture and other industries [1]."

Jan 1, 2012

By Anil Saigal, Jr. Fuller, Said Jahanmir

"All-ceramic crowns, including glass-infiltrated spinel composites, are coming into widespread use because of their superior aesthetics and chemical inertness. This study investigates the residual stresses that are developed in these composites as a result of cool down from the glass-infiltration temperature to room temperature due to slight mismatch in the coefficients of thermal expansion and its effect on the mechanical behavior of these composites. Two-dimensional finite element simulations were performed using an object oriented finite element program OOF. The OOF program is a combination of two programs. The first program, PPM200F, is designed to read an image file such as a micrograph. The individual pixels that constitute the micrograph may be collected into groups and their material properties assigned. PPM200F is then used to create the finite element model/mesh that OOF then reads. The average residual stresses are found to be tensile in the spinel matrix and compressive in the infiltrated-glass. There is large variation in residual stresses and strains from location to location with presence of locations at which the glass is under tensile stress. The crack initiation and initial propagation in glass-spinel composites is at the glass-spinel interface in both the glass and the spinel. The presence of residual stresses can lead to lower crack initiation stresses and degrade the mechanical properties of the composites.IntroductionGlass-infiltrated spinel ceramics are in clinical use as core materials in all-ceramic crowns and as inlays and onlays (1-3). Advantages of ceramic composites include near net-shape forming with high strength in the infiltrated state. Besides, spinel is quite translucent and may potentially be used without a veneer. However, these ceramic composites are subject to damage accumulation from repeat oral contact loading and often fail after a few years of use (4). This paper examines the residual stresses that are developed in these composites, after cooldown from the glass infiltration temperature to room temperature, due to the slight mismatch in the coefficients of the thermal expansion of the two phases."

Jan 1, 2001

By Maria G. Alves, Alexandre M. Stumbo, Francisca M. A. Pinheiro, Jonas Alexandre, Sergio N. Monteiro, Valdo da S. Marques, Paulo R. N. da Silva

"Brazil is among the few countries with potential for developing all sources of renewable forms of energy. In particular, the country is leading the world efforts of substituting petroleum based fuels for biofuels, such as ethanol and biodiesel. Most of the Brazilian petroleum, which has now achieved self sufficiency, is extracted from offshore wells located at the north region of the state of Rio de Janeiro. In view of the future depletion of petroleum, the State University of the Northern Rio de Janeiro (UENF) has created a Center for Alternative Energies (NEAL) to carry out R&D programs on renewable forms of energy. Today, the main project of the NEAL/UENF is a model park for generation of renewable forms of energy. The objective of this work is to present the structural concept of the park and discuss its contribution in terms of scientific, technological, economical and environmental benefitsIntroductionEnergy is presently a key issue in the world agenda for sustained development and environmental protection. It is of common agreement that the existing status of increasing use of fossil fuels, mainly petroleum, natural gas and coal will not only cause depletion of these resources with a consequent elevation in price but also climate changes, especially global warming. In fact, the humankind may be already facing an irreversible situation of climate alterations as well as reduction of conventional sources of energy. The worse predictions foreseen by specialists, still for this coming century, are dramatic disasters due to catastrophic weather in association with a profound energetic crisis. This scenario may, however, be avoided by actions that could effectively tackle the core of the problem. These actions have been suggested and discussed by scientists and leading authorities, especially in international symposia [1-3]. In particular, the Kyoto Protocol proposed goals for reduction of greenhouse gas emissions as well as a mechanism of carbon credits to allow for decreasing CO2 content in the atmosphere without affecting industrial production [3]."

Jan 1, 2008

By M. Wu, A. Kharicha, J. Bohacek, A. Ludwig

"During the horizontal spin casting of rolls, vibrations and mould deformations seems to have a significant effect on the final quality of the product. Sources for vibrations can be found in the poor roundness and a static imbalance of the chill itself. The bending of the mould axis is also considered. Both, vibrations and axis bending, are used as an input for CFD simulations of the flow dynamics of the liquid metal inside the rotating cylinder. The aim is to study the feedback of the free surface behavior in terms of wave propagation and various wave shapes. Introduction The horizontal spin casting process (HSC) is a casting process that has several advantages over the traditional gravity casting processes. Centrifugally cast products have a high degree of metallurgical purity and homogeneous microstructure. A significant gain is observed for the rupture strength, the rupture strain, and the Young modulus. These properties naturally depend on the centrifugal force and thus, the best mechanical properties can be found at the largest distance from axis of rotation. However proper selection of the angular frequency has to be done in order to prevent the so-called ""metal rain"" i.e. metal droplets can fall down from the upper part of the cylinder due to a too weak centrifugal acceleration. In the same time excessive speeds can lead to the appearance of longitudinal cracks caused by the hoop stress in the initially solidified layer. From empirical knowledge other parameters have important influence on the casting products, it includes the pouring temperature, the pouring rate, the mould coating etc. Recently the presence of natural or forced vibrations have been identified as possible additional factors to be taken into account [1-2]."

Jan 1, 2012

By Wayne Bell, Shivanand A. Borkar, Anish Upadhyaya, Matthew D. Andriese, Jiann-Yang Hwang, Zhiwei Peng

"A refractory ore body located in Michigan’s Upper Peninsula contains high concentrations of nickel and copper chiefly occurring in the minerals pyrrhotite, chalcopyrite, and pentlandite. Refractory ore bodies are difficult to treat by conventional mineral processing methods so microwave pre-treatment of the ore is employed to increase metallic-particle/host rock liberation by making use the differential thermal expansion properties of the mineral phases that absorb microwave energy. The Curie temperature measurement of metallic-bearing particles is in agreement with the known value for pyrrhotite occurring at 325°C. A nickel-rich iron sulfide mineral is found to be in occurrence and also appears to be magnetic under BSE imaging. It is shown the ore particles heat rapidly when exposed to microwave radiation for short durations of time mainly due to the high concentration of ferromagnetic mineral phases. Rapid heating causes thermal expansion of constituent mineral phases that produce cracks within ore particles. SEM imaging shows fracture occurring along grain boundaries and throughout host rock matrix. Ball milling experiments show an increased grindability of the ore resulting in a decrease in work index values.IntroductionCrushing and grinding operations consume 50-70% amount of energy used in mineral processing operations [1]. All these processes involve high energy impact of surfaces to develop compressive stresses that produce cracks to initiate breakage of particles. Microwave pre-treatment of certain types of ore might provide an energy savings to these type grinding processes by taking advantage of the tensional forces produced by selectively heating microwave absorbing type mineral phases. The heating of ore particles produces cracking by thermal expansion of the constituent mineral phases. Conventional heating has been investigated and shown to positively aid in grinding processes but determined energy inefficient to be used commercially."

Jan 1, 2011

By Shenghui Guo, Dongbo Li, Lijun Liu, Chengdong He, Jinhui Peng, Libo Zhang

In present study, partially stabilized zirconia (PSZ) was prepared by CaO doped fused zirconia heated by microwave furnace at the temperature of 1450 oC and holding time of 120 min. The XRD results showed that untreated fused zirconia mainly consists of crystalline compounds of cubic ZrO2 phase; while the roasted one mainly is composed of crystalline compounds of cubic ZrO2 phase and monoclinic ZrO2 phase. It is shown through the optimization of structures of two phases that structure of cubic ZrO2 and monoclinic ZrO2 reject each other, revealing its difficulty in forming coinciding interface and linkage of two phases being of Ca atom. Introduction Due to advantages of zirconia, such as high melting point, chemistry inertia, low heat transmission and so on. Zirconia is always taken as megathermal refractory material[1]. However, in the heating and cooling processes of pure zirconium oxide, martensitic transformation will take place associated with greater shear force and volume change, which severely limits the industrial application of pure zirconia in some areas. Such as: Refractory materials, grinding materials and high temperature insulation materials[2]. Through adding a certain amount of MgO, CaO, or Y2O3 stabilizer, etc.[3,4], the zirconia can change into fully stabilized zirconia, which exists in cubic phase. But this high purity fully stabilized zirconia cracks easily because of thermal stress. Therefore, the thermal shock resistance variation is one of the most important quality indicators of zirconia-based materials. According to the heat treatment, the fully stabilized zirconia can be changed into the partially stabilized zirconia (PSZ)[5], which exists in cubic phase and monoclinic phase and has superior mechanical properties, such as anti-heat, low thermal conductivity, large coefficient of thermal expansion and stability, as well as good wear resistance[6].

Jan 1, 2011

By Geir Wedde, Anders Sorhuus

"Vast quantities of energy are released as heat to the environment from industrial operations. Many countries target waste heat recovery to mitigate CO2 emission. Exhaust gases from industries such as primary aluminium smelting, carry a substantial portion of the waste heat generated. For a cost efficient capture of more valuable heat (higher exergy), heat exchangers should operate on the exhaust gases upstream of the gas treatment plants. Heat exchange surface would be exposed to dust laden gases with risk of fouling. Heat exchangers of innovated design and operation have overcome the potential of excessive fouling rates. Heat exchangers of the ""shell and tube"" design have been demonstrated for exhaust gases from ferroalloy as well as primary aluminium smelters. In addition to the heat recovery, gas cooling results in smaller gas treatment plants with lower costs and reduced emission. The aluminium experience is exampled in the paper.IntroductionIndustrial usage of energy continues to grow as a result of increasing volumes of production, a trend that is likely to continue in the coming decades as living standards keep rising globally. World energy consumption (Figure la) is to grow 49 % by 2035 (ref. 2010) as reported by EIA [1]. The industrial sector consumes somewhat more than 50% of the total world energy consumption predominantly the energy increased demand comes from non-OECD countries in Asia. The industrial consumption by production of metals iron and steel accounts for 14 % and for non-ferrous metals 3 % mostly for aluminium production (Figure lb). Aluminium production will be discussed in this paper as an example of an industry with large quantities of waste heat to recover"

Jan 1, 2012

By V. A. Luganov

During the treatment of raw materials containing arsenic and antimony, problems in the distribution of these elements in the process products occur. In a number of cases in processing of copper-bearing materials, it is possible (or necessary) to obtain speiss. The purpose of the present research is to study the theoretical aspects and analyze the technological possibilities of producing copper-bearing speiss and the subsequent electrometallurgical processing with copper extraction as well as arsenic and antimony utilization. Copper arsenide (Cu3As) and copper antimonide (Cu3Sb) are the main components of the speiss. A thermodynamic analysis of the electrochemical oxidation of Cu3As and Cu3Sb, carried out using Pourbaix diagrams, showed that in a pH range from 0 to 2, oxidation potential 0.45-0.55V, ions of copper and arsenic and antimony trioxide are in the equilibrium. The kinetic study has shown, that with an increase in the polarization potential, the dissolution process changes from chemical to diffbsion control. An increase in temperature stabilizes the electrolysis process due to dissolution of arsenic trioxide forming on the anode. Electrolysis of speiss using a cathode diaphragm with the solution pH = 1-2, current density 150-200 A/m2 and temperature 60-70°C makes it possible to obtain cathode copper with a current efficiency of 95-96% and to remove the arsenic from the process during the electrolyte cleaning process. The arsenic content in the cathode copper did not surpass 0.002%. As the result of the research, a technological flowsheet for copper-lead speiss processing was developed. At the present time this technology is undergoing pilot testing.

Jan 1, 1999

By S. G. Kumar, R. G. Reddy

"Niobium aluminides offer the advantage of higher high temperature capability compared to other intermetallic aluminides due to the refractory nature of niobium. However, the reaction sequence in Nb-Al system is sluggish and currently there is a great interest in the processing aspects of these materials. In the present study, a systematic investigation was undertaken to compare the effect of different powder metallurgy processing routes on the phase relations and microstructure of 66Nb-22AH2Ti (in atom percent) alloy. The three different process routes adopted were: (i) cold pressing followed by reaction sintering; (ii) cold pressing and hot pressing followed by sintering; and (iii) arc melting, hydride-dehydride process to make the alloy powder followed by cold pressing and then sintering. The samples are analyzed by XRD, Optical Microscopy, SEM-EDS and EPMA. The analysis showed that alloy pellets made from pre-alloyed powders i.e., arc melting followed by hydride-dehydride process, gave good densification and more Nb3Al formation.1. IntroductionTo improve the performance standards of turbine engines, materials scientists are challenged to develop materials that have· high thrust-to-weight ratio with high specific strength, high specific modulus and good environmental properties at elevated temperatures. The conventional high temperature materials like nickel based superalloys are high in density and hence many of the high temperature materials scientists have focussed their attention on intermetallic aluminides like Fe-AI, Nb-AI, Ni-AI and Ti-AI in recent years. The phase relations and properties of alloys based on Fe-AI, Ni-AI and Ti-AI are fairly well known whereas little is known about the alloys based on niobium aluminides."

Jan 1, 1996

By Susan A. Fredholm, Randolph E. Kirchain, Elsa A. Olivetti, Jeremy R. Gregory, Jeffrey B. Dahmus

"A general model for evaluating the economic and environmental performance of electronics recycling systems is developed. This model comprehends the three main functions in a recycling system – collection, processing, and system management – and aims to enable quantification of the impact of context and system architecture on the economic and environmental performance of electronics recycling systems. Such a model can be used both to evaluate and improve existing electronics recycling systems, as well as to design and implement new systems. A case study, based loosely on Maine, is presented to show the utility of such a model.IntroductionAs recycling systems for complex durable goods (CDGs), and in particular for waste electronics, become more widespread, understanding the economic and environmental performance of such systems becomes critical, both to enable improvement of existing systems and to inform the design of new systems. However, with the range of possible system architectures and the important role of locational characteristics (context), understanding the determinants of system performance is challenging [1]. To address this issue, a modeling framework to project the economic and environmental performance of CDG recycling systems, based on contextual and architectural characteristics, has been developed.The modeling framework presented here comprehends the three main functions – collection, processing, and system management – which are common to most recycling systems. These three functions are modeled using a variety of modeling techniques and serve as a bridge between inputs related to system context and system architecture, and outputs related to economic and environmental performance. The models developed here are intentionally meant to be both broad, in order to address entire recycling systems, and general, such that many different systems, both real and hypothetical, can be analyzed."

Jan 1, 2008

By Chang Wei, Zhigan Deng, Jiqiang Liao, Minting Li, Hongsheng Xu, Yan Song, Cunxiong Li, Xingbin Li

"Abstract: Direct ?otation of oxidized zinc-lead ore is characterized by recovery of zinc and lead only around 55% and 50%, respectively. Mineralogical analysis shows that the sample used in the present study is a carbonate hosted zinc-lead ore, with a zinc and lead carbonate content that accounts for 80.14% and 75.63% of the total minerals, respectively. The carbonate hosted zinc-lead ore was hydrothermally sulfidized with elemental sufur and the experimental data indicated that under the conditions employed up to 75% zinc and 82% lead sulfidation extent were achieved. As a result of pre-sulfidation followed by flotation, the recoveries of zinc and lead into flotation concentrate were over 90%. A flotation concentrate was obtained with 52% Zn and 37% Pb from the materials which was treated by sulfidation.IntroductionSulfide ores are the primary source of zinc and lead, and they are becoming depleted; thus, metallurgical investigators are interested in using abundant oxidized zinc-lead ore reserves. The high-grade zinc-lead oxidized ore, which normally has a zinc content higher than 15%, can be disposed of by acid leaching and electrolysis. However, the low-grade ore, which has a zinc content lower than 10%, is difficult to smelt with pyrometallurgy and hydrometallurgy, and the processes are very complicated and expensive in terms of production flow and energy consumption. Therefore, making the low-grade oxidized zinc-lead ore more beneficial has become more important in recent years. Flotation is the most common process, and the primary method of recovering zinc and lead from sulfide or oxide minerals. It is well known that there is a difference between sulfurized and oxidized minerals regarding their separation by flotation. Flotation of zinc and lead oxidized minerals is extremely complex because of the similarities in the physicochemical and surface chemistry of the constituent minerals. There are no known direct-acting collectors capable of producing single metal concentrates [1-3]."

Jan 1, 2012

By Jianhui Wu, Jing Zhan, Chuanfu Zhang, Zhijian Wang, Chu-ping Xia

"A novel technology about interactive roast of complex bismuth sulfide ore with low grade and Pyrolusite was put forward using the low-grade bismuth sulfide ore and pyrolusite as raw materials. The predominance diagram of Bi-Mn-S-O system was drawn by thermodynamic calculations. Stable coexistence area ofBizO3 and MnSO4 and its control condition was obtained. The interactive roast conditions including roasting temperature, roasting time, the ratio of n(MnO2)/n(S), ventilation rate and so on are investigated systematically. The results show that the sulfur-retained ratio reaches about 98%, in which formation rate of MnSO4 was 94.04%, most of the residual sulfur in the ore exist in the form of BhsO32(SO4)10 in the roasting products The optimum roasting conditions were as follows: roasting temperature of 650°C, roasting time of2h, 1.4 for n(MnO2)/n(S) and 140L/h for ventilation rate.IntroductionBismuth is a ""green"" rare metal with the characteristics of safe, nontoxic and low melting point[l].The use of bismuth and its oxides is extending from traditional fields such as pigment, fusible alloy, bismuth class of drugs and metallurgical additives to the high-tech fields such as semiconductor, high-temperature superconducting materials and nuclear power and so on. Bismuth is one of the precious advantageous resources in China which owns the most abundant bismuth resources in the world. Bismuth metallurgical process is divided into the pyrometallurgy and hydrometallurgy [2-4]. Hydrometallurgy for bismuth is mainly used for the processing oflow-grade complex bismuth ore, whose key steps are oxidative leaching process of the bismuth sulfide ore by strong oxidants(FeCb, Clz, HNO2 etc) in hydrochloric acid system. Therefore, the corrosion of strong oxidants, high demand for equipments and poor operating environment are its inherent disadvantages. Pyrometallurgy for bismuth is mainly used for the processing of high-grade bismuth raw materials or concentrate, which is the main method for bismuth metallurgy at present."

Jan 1, 2013

By Thomas Gliick, Jianming Lu, David Dreisinger

"The Boleo project of Baja Mining (Vancouver) will process a mixed oxide-sulfide ore using an acid oxidation and reduction process in seawater to extract copper, zinc, cobalt and manganese. Copper will be extracted via SX-EW as copper cathode, zinc will be recovered as a zinc sulphate monohydrate crystal and cobalt will be produced as a cobalt cathode product after phosphinic acid extraction. Manganese may be recovered from the final solvent extraction raffinate by precipitation as manganese carbonate.The development of the cobalt recovery process (solvent extraction and electrowinning) will be discussed. The pilot plant solvent extraction circuit and subsequent bench and small pilot testing of cobalt electrowinning will be discussed. The Boleo project will produce approximately 1708 tonnes per armum of cobalt metal when fully commissioned.INTRODUCTIONThe Boleo property is held by the Mexican company, Minera y Metalllrgica del Boleo S.A. de C.V. (MMB). MMB is owned 70% by Baja Mining Corp. and 30% by a consortium of Korean companies consisting of KORES - Korea Resources Corporation, LS Nikko Copper, Hyundai Hysco, SK Networks and Iljin Copper. The project is fully financed and is now under construction with an expected startup in early 2013 .Average annual production, for the first six years for each of the metals is forecast as: 56,697 tonnes of copper cathode, 1,708 tonnes of cobalt cathode and 25,364 tonnes of zinc sulphate monohydrate. The project has an average life-of-mine cash cost (based on the three year trailing average metal prices, as of December 31, 2009, in accordance with SEC guidelines) of -$0.29/lb Cu, net of by-product credits for cobalt and zinc and with no credit for manganese production. There is the potential to produce up to 220,000 tonnes per armum of manganese carbonate (- 100,000 tpa contained Mn) via the relatively simple addition of a small number of unit operations to the proposed plant. The recovery of manganese metals from the manganese carbonate intermediate material is discussed in a separate paper in this proceeding."

Jan 1, 2012

By Fan Xiao-Hui, Jiang Li-Juan, Chen Xu-Ling

"In order to solve air leakage of sintering testing cumbersome, inaccurate results, and other issues, the sinter machine air leakage characteristics were studied, and combining the mathematical modeling and the field detection. The temperature before air leakage was calculated by mathematical model, energy balance equation was established according to sintering process, using Adams prediction correction method which has stronge stability and high precision, to solve hyperbolic partial differential equation with astringency problem. The temperature after air leakage is detected by instruments, according to energy conservation calculation the sintering air leakage rate. According to the sintering continuity and periodicity, sintering air leakage location diagnosis expert system was established to judge specific air leakage locations.IntroductionStrengthening of modern blast furnace production depends on the quality of the raw material preparation to a large extent [1]. Technical and economic index of modern blast furnace production is advanced; the most important reason is the use of concentrated feed. Sintering plant is the ""kitchen"" of blast furnace’s concentrate. As we all know, sintering plant is major energy consumption of steel plant, in sinter process energy consumption, the solid fuel consumption of total energy consumption is 75%~80%, power is 13%~20%, ignition and combustion is 5%~10%. To reduce the air leakage of sintering plant is an effective measurement to save energy consumption. At present, our air leakage of sintering compared to the other developed countries is still a long way to go. Japan’s air leakage rate is about 30%, and 35%~60% air leakage of sintering machine at home, a big gap exists between the plants. At present the determination of air leakage is all for manual operation, long measuring period, considerable manpower and resources, and the results are significantly affected by operation. For air leakage of sintering control lag issues, research and development of diagnosis expert system for on-line monitoring model for air leakage and, through this research can reduce the use of detection equipment, detect sintering air leakage, improve the yield and quality of sintering production, reduce energy consumption, and extend equipment life span."

Jan 1, 2012

By Alexander V. Derevyanko, Victor P. Popov, Alexander I. Raitchenko

"If an electric current flows along some electroconductive suspension in columnar form the solid particles are 'experienced thermal, mechanical, and electromagnetic influences.The objects were suspension Sn (liquid) - Ni-Cr-Mo-W alloy (solid particles). This is refractory alloy on the Ni base. The direct constant current (with density -106 A/m2 ) flowed through the named suspension during 180+300 sec. At the beginning of experiments samples were ones containing particles suspended uniformly in volume. Although density of solid particles was ~9x103 kg/m3 , i. e. higher than density of liquid Sn (-6.8x103 kg/m3 ), after end of this processing, the non-uniform distribution of particles in volume of samples was observed: concentration of Ni-alloy particles in lower part was smaller than their concentration in upper part of samples, and simultaneously their concentration is increased near outer surface. There was probably the natural convection of Benard-Rayleigh type which had carried, so lid particles upwards, and, in same time, there was the action of spatial Lorentz-forces directed to center forcing the radial movement.The knowledge of named phenomena can be useful for elaboration of technology of gradient dispersed materials and development of some materials science fields.IntroductionThe liquid metal with the electric current or under the alternating magnetic field is experienced compression. This action causes the pressure within metal and the change of the surface of the metal column (see, for example, [1-4]). One of results of such an electromagnetic compression is extraction of the foreign solid particles from a cylindrical liquid sample to surface in the radial directions. However, more complicated paths of the inclusions are observed under some conditions of electric treatment."

Jan 1, 1999

By Zhang Jianliang, Zuo Haibin, Gao Bing, Wang Zhe

"As a result of the shortage of coking coal and the quality decrease of coke, it is important to know how to make better use of highly reactive cokes. The co-gasification behavior of highly and lowly reactive coke for blast furnace is investigated. The results show that: In the middle stage of reaction, the weight loss ratio of highly reactive coke reacted together with lowly reactive coke is higher than that of it reacted individually. However, the weight loss ratio of lowly reactive coke is lower. The weight loss ratio of highly and lowly reactive coke is almost the same as that of the weighted average. The scanning electron microscope analysis indicated that the reaction degree of surface and interior of lowly reactive coke is relatively uniform with the reaction time increased. And the reaction degree of surface of highly reactive coke is obviously higher than that of interior.IntroductionIn blast furnace iron making process, coke functions as heat supplier, reducing agent, carburizer and skeleton. With development of blast furnace iron making technology, the skeleton function of coke is becoming more and more important in requirements of large scale furnace and high pulverized coal injection. High reactivity coke is usually produced by cheap coal with bad quality, and is not good for blast furnace process. The reactivity of coke is mainly determined by the coals used, and the resource of good quality coking coal is limited and is non-renewable. In order to fulfill the need of blast furnace, a lot of research have been done to improve coal matching using new kinds of coal to enlarge resource, in which coking coal and fat coal are reduced, whereas low price coal with bad caking property are used to lower the cost, and this would inevitably increase the reactivity of coke [1-4] Blast furnace iron making would still be the main stream for a predicted future, and high reactivity coke would correspondingly be used more and more, so it has great importance to study how to use high reactivity coke in blast furnace."

Jan 1, 2013

By Kinya Atsumi, Kanjana Khunathai, Hisaya Kato, Hidetka Kawakita, Keisuke Ohto, Katsutoshi Inoue

"Crosslinked microalgae were prepared from the residue generated in the production of biofuel, by crosslinking-condensation in concentrated sulfuric acid. These microalgae were tested for adsorption of various metal ions in hydrochloric acid medium. The crosslinked microalgae exhibited high selectivity for Au(III) over other precious and base metal ions. From an isotherm experiment, the maximum adsorption capacity was evaluated to be 3.25 mol/kg of dry gel for Au(III) which was many times higher than that of the original microalgae residue. SEM and X-ray diffraction confirmed the formation of metallic gold particles, suggesting the occurrence of a redox reaction between surface functional groups on the gel surface and trivalent gold ion.IntroductionSubstantial quantities of precious metals are being used by the electronic industry because of their excellent electrical conductivity and resistance to corrosion. In recent years, recovery of precious metals from secondary sources such as electronic scrap [1,2 ], and leach liquors is being favored because of environmental concerns. Of course, recovery is only practical, if its cost is lower than the value of the metals (gold, platinum and palladium) recovered.Traditional methods of separation and refining do not fulfill this requirement. In order to overcome this problem, attempts have been made in recent years to develop new processes including total leaching in hydrochloric acid containing chlorine gas or hypochlorite, followed by solvent extraction and ion exchange [3]. In the new processes, new solvent extraction reagents or ion exchange resins with high selectivity and high loading capacity are used to simplify the process and to reduce the operating costs."

Jan 1, 2011

By Xi-Shan Li, Qian Li, Yong-bin Yang, Li-na Cui, Tao Jiang, Jie Ge

"With regard to control environment pollution in the roasting pretreatment of sulfur & arsenic-bearing gold concentrate, roasting of double-layered pellet was proposed. In the paper, the characteristics of double-layered pellet roasting were studied. Removal and solidification rates of sulfur and arsenic were investigated as primary factors. The result indicated that the removal and solidification rates of arsenic reached up to 95.91 % and 98.95% while the sulfur was 97.19% and 97.90% respectively on the premise of adopting slaked lime as solidified agent at temperature of 6000, the package proportion of 2.14 and roasting time of 3h. However, pyrite and arsenopyrite were transformed to hematite and magnetite and product of solidification mainly consisted of calcium sulfate, calcium arsenate and calcium sulfite within optimum roasting parameters.IntroductionUtilization of refractory gold resources has been gradually concentrated on with the depletion of the gold resources which are easy to deal with in the world [1]. Sulfur and arsenic-bearing gold ore is a typical refractory gold one, in which ultrafme gold is encapsulated in the structure of metal sulfide minerals [2,3], so it gives poor recovery through direct cyanide leaching. These refractory ores need pretreatment before the process of cyanide leaching to undermine lattice structure of pyrite and arsenopyrite containing gold [4] so that the gold could touch with cyanide solution [5]. Among various methods of pretreatment, conventional roasting method is most effective, but this process generates gases such as S02 and As203 harmful to environment. Therefore solidification roasting was proposed to solve this problem occurring in the conventional roasting at the end of last century."

Jan 1, 2013

By Ray Y. Lin, Sunil G. Warrier

"Low cost processing of metal matrix composites is an essential requirement for this class of materials to be acceptable in commercial application. In an effort to reduce the cost of processing of metal matrix composites, an infrared pressureless liquid infiltration technique has been developed. The salient features of infrared infiltration are that it is rapid, simple and a low cost process. The rapid processing capability causes very little oxide formation on the alloy resulting in both improved wetting and flow characteristics and reduced oxygen contamination in the composite. Thus, vacuum is normally not required. Using infrared inflltration, aluminum and titanium matrix composites have been prepared under an ambient argon atmosphere. Reinforcements in these composites include carbon fibers, silicon carbide Nicalon fibers and Textron's SCS fibers. Microstructural and mechanical test results indicate that completely consolidated composites with good fiber distribution, limited interfacial reaction and high mechanical properties can be manufactured by this process. IntroductionAluminum and titanium matrix composites reinforced with ceramic reinforcements are strong candidates for numerous applications in the aerospace and automotive industries. Aluminum matrix composites are commonly fabricated by either solid state vacuum hot pressing, liquid state pressure infiltration or squeeze casting [1]. Although liquid state pressure infiltration and squeeze casting has significant advantages over solid state processes, the requirement for pressure makes these composites uneconomical for large scale industrial application. Titanium matrix composites are primarily fabricated by solid state diffusion bonding [2]. Pressureless liquid infiltration can significantly reduce the cost of fabrication in both the composite systems. However, during pressureless infiltration processes, several complications concerning the wetting characteristics and chemical compatibility arise."

Jan 1, 1994

By Jianxun Song, Hongmin Zhu, Qiuyu Wang, Jungang Hou, Shuqiang Jiao, Xiaobo Zhu

This work presents the results of a study on the Ti3+/Ti2+ couple redox potentials vs. Cl–/Cl2 at the temperature range (673 to 1073 K) in fused LiCl-KCl eutectic by direct potentiometric method. Initial concentrations of TiClx in solvents did not exceed 5.0 mol%. Basic thermodynamic properties of the reactions TiCl2+1/2Cl2(g)=TiCl3 were calculated using the temperature dependencies of apparent standard potentials of the couples E* Ti3+ /Ti2+.

Jan 1, 2014