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By C. M. F. Vieira

Crushed fired brick waste, known as grog, screened at two different particle size, 840 (20 mesh) and 180 µm (80 mesh), was used in mixtures with clayey body to make typical red ceramics for bricks. The effect of the grog addition up to 20 wt.% on the properties of bricks fired at 700oC was evaluated. The results indicated that both the particle size and the amount of grog addition changed the fired properties of the clayey body. Additions above 5 wt.% of grog, with a coarser particle size, decreased the mechanical strength of both the dry body and the fired ceramic pieces. By contrast, grog with a finer particle size may be used up to 10% wt. without deteriorate the properties and corresponding microstructure of the clayey body.

Jan 1, 2009

By Tiruttani Munikamal, Suresh Sundarraj

"A numerical model of the induction hardening process of steel cranks has been developed and the predicted results of temperature and phase distribution during this solid state phase transformation process are verified with experimental data from the literature. This heat treatment process involves heating the crank to the austenitic temperature range followed by rapid quenching in water to harden the surface of the crank. The model has been developed using ABAQUS, commercial FEA software. The formation of martensite, pearlite, and retained austenite phases are modeled and implemented through a user defined function in ABAQUS. A sensitivity study on the various process parameters affecting the amount of phase distribution has been carried out.IntroductionThe type of surface and sub-surface microstructure as well as the residual stresses that are present in a component after manufacturing, significantly affects it fatigue performance. The wear resistance of the automotive components such as crankshaft, gears, camshaft and bearings depends on the surface hardness. In order to achieve the surface hardness, these steel components are subjected to a type of quench hardening heat treatment process. There are several heat treatment processes available for the industrial application to improve the mechanical properties of the final part. Case hardening using induction heating is one of the widely used industrial techniques for improving the surface microstructure of a steel component. It consists of two stages i.e. induction heating cycle, followed by quenching in a fluid medium (usually water or oil)"

Jan 1, 2012

By M. E. Reed

Clyde Materials Handling (CMH) and WorleyParsons have developed a concept for a flash furnace feed system using the specialist pneumatic conveying equipment expertise of CMH and the flash furnace process experience of WorleyParsons. CMH has developed a proprietary volumetric feeder (called a Rotofeed) which is extremely accurate and overcomes many of the problems inherent with loss-in-weight screw feeders and drag chain conveyors, previously regarded as state-of-the-art. Initial indications are that the Clyde-WorleyParsons Feed System could deliver the following benefits to Flash Furnace operation: ? Accurate pulse-less delivery of feed material to the head of the burner leading to improved combustion performance and process stability; ? Highly accurate split to the individual quadrants of a conventional burner tube, or provision of a smooth hollow curtain to a burner without guide vanes; ? Decreased pressure pulsation in the furnace due to improved combustion control and performance; ? Decreased temperature fluctuations in the furnace due to improved combustion characteristics and hence reductions in refractory thermal stress and wear; Plant measurements have indicated a correlation between the discharge of concentrate from the drag chain conveyor and high speed pressure fluctuations in the flash furnace settler. Pilot scale test have been conducted to illustrate that the system delivers pulse-less feed to the burner with even feed distribution axially.

Jan 1, 2006

By Justin Karl, Ali Gordon, James DeMarco, Yongho Sohn

"Aluminum metal-matrix composites are lightweight materials that have the potential to supplant steel in many applications. The current work helps to identify the parameters that confer maximal strength and ductility. Torsion tests were performed on the as-cast aluminum metal-matrix composite A359-SiCp-30% at a variety of temperatures and twist rates. Dependence of material properties on temperature and strain rate were identified from equivalent stress-strain curves constructed from the reduced data. Examination of the microstructure was performed on the as-cast material and on fracture surfaces. A temperature-and strain rate-dependent constitutive model was applied to simulation of the mechanical response of the torsion specimen. Trends in material properties corroborate and extend trends identified previously under tensile loading with regard to temperature and strain rate dependence. Shear properties of simulated specimens agree with properties obtained through experimentation.IntroductionAluminum metal-matrix composites (A1-MMCs) have become increasingly popu1ar in recent years. While unreinforced aluminum alloys have low densities and high ductilities, they are not suitable for many applications due to their lack of strength and stiffness. To provide added strength and stiffness while maintaining favorable densities, it has become common to reinforce aluminum alloys with silicon carbide in various forms, although usually the inclusions are in the form of whiskers or particles. The result is a composite material with superior specific strength and stiffness. While whisker-reinforced composites are expensive due to the necessity of processing by nonstandard techniques and have low transverse properties when rolled, particle reinforced Al-MMCs have transverse material property values almost as high as the longitudinal properties and are not as expensive to process as whisker-reinforced Al-MMCs [1]."

Jan 1, 2012

By Makiko Takahashi

A tool is being developed to predict and visualize the microstructural evolution of steels during quenching. This tool utilizes experimental data and reference data that are stored in a database to predict the microstructural development. The visualization tool animates qualitative representation of two- dimensional microstructure drawings as well as the quantitative volume fractions of phases present as a function of time. This is achieved by superimposing the Jominy End-Quench test results over the Continuous Cooling Transformation diagram of the alloy. The predicted microstructure is presented through the web browser to maximize the ease of use. In addition, a parallel coordinate system is used to aid in identifying similarities within the data set by presenting the large number of data at a glance. The results for 4140 steel that was quenched in a wide variety of quenchants will be presented to illustrate the prediction and visualization tools. Keywords: Quenching, Microstructure Prediction, Simulation, Data Visualization, Database, Applet, Animation

Jan 1, 2003

By M. Hamamoto, S. Tanaka, K. Noda

"Tamano Smelter or Hibi Kyodo Smelting Co. Ltd. is operating with the Tamano Type Flash Smelting Furnace method which is a flash smelting furnace without slag cleaning furnace but which can discharge a slag equivalent to that from the slag cleaning furnace and with the development or coke combustion technology which is the basis of this world's only one type flash smelting furnace process, the smelter exhibits a low operation cost under high productivity operation. Utilizing this experience and improving it we have developed and put to practice an operation guide system using a general purpose computer in order to further establish s stable operation. In this paper these improvements are described. Background of System DevelopmentWith the recent rapid progress of general purpose computers and improvements in their performance an environment for the use or computer in process simulation at low cost and simple operation has been established. If an accurate operation simulation can be done with the Tamano Type Flash Smelting Furnace the merits would be very great and thus we started development of the system. The official name of this system is Computer guide system for Coke Combustion in the T-FSF and taking the initial letters we call it CCCT. We aim to achieve operation with stable mane grade, temperature and slag loss in the furnace by maintaining the most suitable combustion conditions of concentrate and coke in the flash furnace with the assistance of CCCT to the flash smelting furnace operators.Through several production expansion projects clone in the past by oxygen enrichment the copper concentrate treatment quantity and matte grade have increased step by step as shown in Figure I. Following this increase the difference between the operation calculation results al the initial stage of coke combustion and the actual behavior of furnace (matte grade. temperature in the furnace. etc.) gradually became bigger. Further operation procedures taken by different operators against the same phenomenon were sometimes different depending on each individual, which from time to time caused the operation to become unstable. Prior to the development of the system we checked out thoroughly the weak points of operation calculation procedures which were in practice until that time. The results were analyzed and study was carried out to establish a most suitahle operation calculation procedure and finally we reached this system"

Jan 1, 2000

By Hiroyuki T. Takeshita

Ca-Ni based alloys were investigated on structures, hydrogenation properties and the effect of additive elements on hydrogenation properties. CaNi, samples were decomposed to form a new hydride with a CsCl-type structure on the constituent metal atoms at high temperatures such as 673K in a hydrogen atmosphere. The candidate of the third element which was added to stabilize the original compound was investigated by using the Miedema's semi- empirical model and, as a result, Pd was chosen. The hydrogenation of CaPd was conducted with a Sieverts' type apparatus and the synthesis of Ca-Ni-Pd ternary alloys was performed by high frequency heating.

Jan 1, 2002

By Junmo Ahn

This study investigated leaching kinetics by alternative lixiviants for copper leaching from chalcopyrite (CuFeS2), the most abundant copper resource in the world. As a refractory sulfide mineral, chalcopyrite shows low copper extraction due to passivation on chalcopyrite surface. Also, decrease of copper grade with high portion chalcopyrite requires the alternative leaching procedure to increase copper recovery. Therefore, alternative lixiviants such as sulfurous acid and methanesulfonic acid (MSA) were tested for both concentrate and low grade ore to enhance copper extraction. Also, an oxidant, hydrogen peroxide, was compared to ferric to find out the improvement of leaching kinetic. In concentrate leaching tests, 30 g/L MSA showed the highest copper extraction (47%), compared to other lixiviants at 75 °C. Periodical H2O2 addition enhanced copper extraction, and above 90% of copper extraction was observed within 96 h by periodical addition of 0.6% H2O2 at 75 °C. The activation energy of chalcopyrite leaching by MSA and H2O2 achieved 40 kJ/mol, which is chemical reaction control. The results of low grade ore leaching tests indicates that no significant difference among lixiviants (H2SO4, H2SO3 and MSA) with ferric was observed, all of which achieved around 37% within 24 h at room temperature. However, significant increase of copper extraction (>80%) was observed at both 20 g/L MSA and 10 g/L H2SO4 conditions by the addition of 10% H2O2.

By Run Huang, Xuewei Lv, Lei Lei, Guibao Qiu, Chenguang Bai

"The TiO2-rich slag and pig iron can be produced from ilmenite concentrate by the electric furnace process. In this study, ilmenite concentrate was reduced in a vertical furnace equipped with a weighting data acquisition system. The effects of reducing agent (carbon) amount on the iron reduction were studied. The phase transformation, morphology and chemical compositions of reduced samples were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), respectively. It was found that the reductive degree of ilmenite concentrate increased with the increase of reducing time. The phases of reduced samples were mostly iron, rutile, Ti3O5 and Fe2TiO5. The mass loss percentage increased with increasing the carbon amount from 8% to 12%. When the carbon amount exceeded 12%, the mass loss percentage decreased with the increasing of carbon amount.IntroductionIlmenite and rutile are the main raw materials for producing titania pigment and titanium metal. With the development of the titanium industry, huge amounts of titanium resources are needed. As sources of high-grade titania mineral decrease worldwide, more attention should be paid to the processes involving low grade mineral such as ilmenite ore. In ilmenite, MgO and CaO are the gangue parts. Therefore, the ilmenite refining becomes more and more popular. In the previous studies, the methods of ilmenite refining are electric furnace smelting, direct acid leaching, selective chlorination and thermal reduction [1]. Electric furnace smelting method is widely used in the titanium industry, however, which consumes a great deal of energies and has a high CO2 emission. Its essence is to remove iron oxides and obtain a high titania slag. So the thermal reduction of ilmenite concentrate is an important step in titanium industry, which can decrease carbon reagent consumption and save energy.Over the past several decades, many studies have been carried out on the mechanism and kinetics of the reduction of different ilmenite ores, which are as follows: The carbothermal reduction of Panzhihua ilmenite initiated at about 860 oC. In the temperatures ranging from 900 oC to 1400 oC, the reaction rate was changed like a shape of “M”. That was to say that the reaction rate increased with the growth of temperature at first, then decreased, afterward increased again and at last the reaction was arrested [2]. The Mohammad A.R group [3, 4] showed that the carbothermal reduction of primary ilmenite concentrate was faster in hydrogen and initiated at a lower reduced temperature than in argon and helium. The reduction in argon and helium had about the same rate and extent. Titanium oxycarbide started at 1000°C in hydrogen. The conversion of primary ilmenite concentrate to metallic iron and titanium oxycarbide at 1200 °C was completed in 300 minutes. Monoxide as the reductant to reduce ilmenite had been studied intensively by a few research groups [5, 6]. The rate and the degree of reduction depended on the formation of a metallic shell of iron which inhibited the transfer of CO to the reaction zones; titanium had a strong effect on the mechanism and rate of reduction of iron oxides. Wang and Yuan [7] studied the reductive kinetics of the reaction between a natural ilmenite and carbon. At temperature below 1100°C, chemical reaction was the rate controlling step, at 1100 to 1250°C mixed controlling was rate controlling step, above 1250°C diffusion through the product layer controlled the reaction. Zhang [8] investigated the reduction of natural, sintered and preoxidized ilmenite concentrates in hydrogen methane mixtures. Preoxidation and sintering of ilmenite concentrates changed their phase composition and caused a sharp decrease in specific surface area of raw materials and an increase in carburization temperature. Sintering also increased the metallization temperature of iron."

Jan 1, 2011

By Isabella Lancellotti, Fabrizio Passarini, Luisa Barbieri, Fernanda Andreola, Ivano Vassura, Luciano Morselli

"The techniques able to incorporate wastes by means of a heat treatment present the advantage to fix the residue with chemical bonds. Among these techniques there are vitrification and sintering which are characterised by different operating temperatures in the range of 950-1500°C and the involved raw materials develop silicatic crystalline phases and glassy matrices capable to immobilize heavy metal contents in the waste matrix. In this work incinerator bottom ash, polishing and glazing ceramic sludges have undergone to thermal treatments in order to valorise the waste as secondary raw material for the obtainment of re-products. The chemical efficiency of the process adopted has been evaluated by comparing the results of release tests applied to the as-received wastes and to the thermally treated materials in order to verify the effectiveness of the different matrices to fix the waste components.IntroductionVitrification is one of the most promising technological options for the treatment of some kinds of waste. The high temperature involved in the process (1200-1500°C) leads to the complete destruction of organic pollutants, such as dioxins, and glassy network formed can incorporate heavy metals. Some vitrification processes naturally occur: glasses produced by volcanic eruptions, such as obsidians (Na2O-K2O-Al2O3-SiO2) and basaltic (CaO-MgO-Al2O3-SiO2) rocks, are basically inert materials even when they contain toxic elements, because these are embedded in an extremely stable glassy matrix. The disadvantage of vitrification is that it is an energy-intensive process involving relatively high costs, therefore its use is better justified if a high-quality product with optimised properties can be fabricated. The most effective way to improve the properties of the vitrified material is the transformation into glass ceramic. This is a fine-grained polycrystalline material (typically from 50% to 98% of the volume may be crystalline) formed when a glass of suitable composition is heat treated and hence undergone to controlled crystallisation (phenomenon named devitrification). The three key variables in the design of a glass-ceramic are: glass composition which controls glass viscosity related to the effectiveness of nucleation and rapidity of crystallisation; glass-ceramic phase assemblage (that is, the types of crystals and the proportion of crystals to glass) which is responsible for many of the physical and chemical properties; nature of the crystalline microstructure (crystal size and morphology and the textural relationship among the crystals and glass) which is the key to many mechanical and optical properties. In particular, a partly crystalline material can be obtained by powder sintering."

Jan 1, 2008

By José Brant, Douglas Torres, Rogério Navarro, Rodrigo Souza, Eduardo Brocchi

The steelmaking process requires the input of ferro-alloys to implement the adjustment of some elements composition in the final product. In the particular case of stainless steel production, the high carbon FeCr alloy stands out as one important precursor. However in the production of this material a certain quantity of fine powder with remarkable chromium and carbon content is also generated, which, in turn, could be processed through alkaline roasting in order to selectively recovery this element in a subsequent aqueous route. In the present work, this process is investigated, using excess of NaOH as oxidizing agent, and H2O2 for precipitating chromium as Cr(OH)3, which is next calcinated to Cr2O3. According to the results, the global achieved recovery has shown to be around 98%, suggesting that the proposed route can be seen as a potential process for chromium oxide production from the mentioned fine powder.

Jan 1, 2015

By Minting Li, Hailong Yang, ChangWei, Cunxiong Li, Gang Fan, Xingbin Li, ZhiganDeng

The filtration problems on acid leaching sludge of high silicon zinc ore have been paid extensive attention in zinc hydrometallurgy. It was found that soluble silica can be effectively converted into silica precipitate with good settling, filtration and washing properties, and the filtration rate can be in excess of 800 L/m2 · h under certain leaching conditions. According to investigating on the filtration rate, viscosity and concentration of silica of leaching sludge or liquor, the filtering temperature can tremendously improve the filtration property of pulp. At the same time, the experimental data indicated that the viscosity of leaching liquor was the key factor influencing filtration property of leaching sludge.

Jan 1, 2016

By Jiang Feng, Zhang Libo, Peng Jinhui, Guo Zhanyong, Ju Shaohua, Lei Ting

The clean utilization of the residue containing chloride, CuCl residue, produced from zinc hydrometallurgy is very important for the recycle of valuable metals. And drying is the main process in recycling. In this study, response surface methodology was used to optimize operating conditions of the drying of CuCl residue in a convection oven and desirability function used as the methodology for the optimization. Optimization factors were air temperature (80–100°C), material thickness (10–25mm) and process time (80–120min) while investigated responses was final moisture content. The optimum conditions were found to be the temperature of 95.48°C with the material thickness of 13.47mm for the process time of 89.48 min. Under optimum conditions, the predicted moisture content of CuCl residue was 4.11% while the experimental date was 4.13%. The experimental value after process optimization was found to agree satisfactory with the predicted value. After drying, XRD was used to analyze the main phases of CuCl residue. The CuCl residue is made up of CuCl,Cu2O, ZnS and other compounds.

Jan 1, 2015

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 Daniel Kittelty

A fully instrumented laboratory electrowinning cell has been used to produce nickel cathodes from synthetic solutions containing various impurities in order to evaluate the effects of both metallic ions and organic reagents (from prior solvent extraction and other processes) on the quality of the electrodeposited nickel. The conditions used were typical of those employed in industrial electrowinning operations. The impurities were found to alter the crystal size and shape, induce the development of hydrogen pits on the deposit surface, incorporate as metal hydroxide crystals in the deposit, and alter the internal stress and current efficiency. These effects have been interpreted in terms of previously established relationships between the solution composition and the physical properties of the cathodes. The incorporation of the common metal impurity ions into the deposit have been interpreted in terms of a mass transport controlled reduction or precipitation reactions. In particular, a low concentration of aluminium ions resulted in an initial highly deleterious effect, which was replaced by a positive influence at higher concentrations. A model which involves the buffering effect of the aluminium on the pH at the cathode surface has been proposed.

Jan 1, 2003

By Robert Corson

Zinc has a large solubility in Fe and a completely filled ?d? shell. With the discovery of dramatic increase of the magnetostriction in Fe by Ga addition, an examination of element Zinc that is adjacent to Ga in the periodic table is of significant interest. In this work, the effect of binary alloying of Zn with Fe on the magnetic and magnetostrictive properties is examined. The FeZn alloys were processed using powder metallurgy and vapor phase synthesis, and Zn contents were varied from 5% to 30%. An examination of the influence of different processing parameters and the Zn content on the resulting alloy properties is presented. The alloys were characterized using X-ray diffraction and SEM. Magnetostriction measurements were carried out at different pre-stress levels. Magnetic properties were measured using a vibrating sample magnetometer.

Jan 1, 2006

By Fernando Guevara

Many smelting and slag-cleaning furnaces operate with cooling systems designed to freeze a slag layer over the refractory to protect it. The fluid flow and heat transfer conditions associated with the freeze layer and mushy zones are poorly understood. These phenomena were simulated with a small-scale room temperature, 2-dimensional model, using an aqueous solution of calcium chloride to simulate the slag. Reasonable similarity with conditions encountered with copper and nickel smelting systems was achieved (Pr 50 and Ra 108, in the laminar-turbulent transition). Measurements of the freeze layer development and velocities were made with the Particle Image Velocimetry (PIV) technique. Direct Numerical Simulations (DNS) were also made of the unsteady fluid flow and heat transfer problem. It was found that the solidification process is well described using an improved model for high molecular viscosity in the mushy zone. Solid front growth, isothermal profiles, velocity profiles and heat transfer through the walls showed good agreement between the PIV and DNS results. Experimental and numerical velocity profiles close to the freeze layer show a parabolic behaviour in the vertical velocity profile which is completely different from the calculation of heat transfer using a sharp interface model. The reason for this is attributed to the effects of the mushy zone with a high viscosity and high shear stresses acting on that area.

Jan 1, 2006

By Run-sheng xu, Hai-yang WANG, Di ZHAO, Teng-fei SONG, Jian-Liang Zhang

This paper was mainly focused on the different semi-cokes and charcoal which could be new fuels for blast furnace injection. Through the comparative study with bituminous coal and anthracite coal, the properties of semi-cokes and charcoal were presented in this research. 10 indexes of different fuels were obtained by different standard experiment, including proximate analysis, ultimate analysis, igniting point, explosivity, transportation characteristic, ash properties, grindability, calorific value, combustibility and reactivity with CO2. According to the data analysis, it provided a theoretical basis for rational utilization of various blast furnace fuels, and helped to broaden the scope of the blast furnace injection fuels. This research could contribute to energy conservation, emissions reduction, and sustainable development of iron and steel enterprises.

Jan 1, 2015

By André L. B. Bittencourt

The copper content in the waste slag represents the greatest loss in the process of Caraíba Metais' Smelter. By identifying the variables responsible for copper stabilization in the slag, a minimization on these losses is expected, producing a granulated waste slag with a copper content lower than 0.7%. Statistics resourses such as control charts, Pareto's diagram and correlations curves were applied for the data obtained in the first semester of 1992. The magnetite and the calcium oxide contents in the slag of the Flash Smelter Furnace were most prominent variables. Some operational changes introduced during and after this investigation have shown good results.

Jan 1, 1994

By Bob Hannah, Peter C. Hayes

The changes that are happening in the world of metallurgy, and with it university education, are generational and require generational responses. Some of the key issues facing metallurgical education and ongoing professional training are explored. What will be required of metallurgical engineering professionals in the coming decades? What knowledge and skills will be needed? How to provide the educational and learning pathways, and how to attract smart young people into this profession? These are issues more readily addressed by tertiary institutions in conjunction with industry; perhaps the greater challenges lie in building and maintaining competencies post-graduation. There is a need to establish and maintain a system that supports graduates and enables them to develop further into competent expert engineers able to successfully address complex engineering challenges.

Jan 1, 2014