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By Jiangwei Shen, Cong Wang, Haibin Zuo

The research on the formation of Silico-Ferrite of Calcium and Aluminium (SFCA) in the process of cooling and solidification is rarely reported. The crystallization process was observed by using scanning electron microscopy (SEM) and optical microscope in this paper. The effect of different cooling system on the microstructure and phase composition of the sinters was investigated to obtain the appropriate cooling rate to improve the metallurgical properties of sinters. The experimental results show that the crystallization of calcium ferrite is getting better when the cooling rate is decreased from water quenching to cooling in the air. There are a large number of hematite phases with interconnected crystal structure in the sample cooled in the air. In the case of the compressive strength, it was determined by the mineral composition and pore structure, higher SFCA and hematite contents in sinter cooling in the air lead to a higher strength. Glass phase in the water quenching sinter was the major reason for the lowest strength. High porosity contributes to a decrease in compressive strength for the sinter cooling in the furnace. Therefore the air cooling was the appropriate cooling rate to achieve high quality sinter under this experimental condition.

Jan 1, 2016

By Ernt. W. D.

A membrane based mixed extractant process was developed for selective removal of copper from waste acidic cupric chloride etchant solutions found in printed wire board manufacturing. The process uses a mixture of Adogen 381 (tri-isooctylamine), MOC®-45 (ketoxime) and MOC® 55TD (aldoxime) in a kerosene diluent. The mixed extractants recover the copper from a hydrochloric acid medium and transfers it to a sulfuric acid medium. The process also utilizes unique wetted membranes to separate the aqueous and organic phases. The driving force for these membranes is not pressure but the difference in surface tension between the two phases. By using these membranes, complete phase separation results. There is no physical entrainment contamination as found in conventional systems. The only cross contamination is the solubility concentration of one phase in the other. This however is less than 10 mg/l.

Jan 1, 1998

By Matthias Merzkirch, Volker Schulze, Kay Andre Weidenmann

"Unidirectionally reinforced light weight compounds based on light metals such as the aluminium alloy EN A W-6082 are adequate materials for the future use in transportation means like automobiles and airplanes. Due to the occurring cyclic loads knowledge about the crack growth behaviour of such composites is needed. The investigations at a load ratio of R = 0.18 show that the crack growth rate of the aluminium matrix is reduced if reinforced by spring steel wire with a reinforcing ratio of only about 1 Vol.-%. Additionally, the acoustic emission analysis allows detecting crack growth within the matrix material, crack propagation along the interface wire/matrix and crack closure which could also be determined with the help of a self designed capacitive displacement measuring gauge. The damage behaviour could be verified by metallographic and SEM investigations.IntroductionIn the field of lightweight structures for transportation means the need for light, strong and stiff materials, in particular composite materials, is increasing in order to save resources and costs. Lightweight materials such as aluminium and magnesium alloys are highly efficient candidates to be used in the composite extrusion process [1] which allows for a simple production of unidirectionally reinforced profiles with a large diversity of geometries at low costs. Figure 1 depicts the principle of the composite extrusion process; within the first part of the tool the billet material is split into several strands whereas the middle part of the tool allows the supply of the reinforcing elements. The third part of the tool rejoins the matrix material and the reinforcing elements and defines the final shape of the profile."

Jan 1, 2011

By M. Waladan

The top submerged lancing Sirosmelt system has been developed through laborator.y scale testwork and pilot plant trials for recovery of zinc from ISF slag. The effects of the process variables of gas injection rate, method of coal feeding, and temperature on zinc fuming rates were studied in the laboratory. It was found that the rate of zinc elimination was dependent on all of these variabl.es. The rate of zinc removal from slag was independent of zinc content of slag down to approximately 1.5% Zn, below which the rate was proportional to zinc content in slag. Pilot plant trials were carried out to evaluate a proposed process and results followed predictions from the laboratory scale tests. A comparison of the proposed process with conventional slag fuming operations is made and it is shown that the process has a number of advantages which have a significant impact on the economics of zinc slag fuming.

Jan 1, 1990

By J. Pérez

A lead smelter slag with high copper, lead, arsenic and silver contents was treated at laboratory scale for arsenic removal. The slag was first leached at atmospberic pressure with sulfuric acid and oxygen. According to arsenic contents leaching of most of the arsenic was achieved in either one or two stages, producing a lead-silver rich residue and a solution high in copper and arsenic concentrations. Alternative routes were considered to treat the resulting solution. Firstly, solvent extraction of arsenic with a mixture of TBP and 2-etbyl-bexanol was tested and extractions of over 95 percent of arsenic were achieved. Secondly, a copper arsenate precipitation treatment was done to eliminate arsenic and copper from solution.

Jan 1, 1996

By J. A. Bustnes

The present work deals with kinetic studies of the reduction of molybdenum- and tungsten oxides by hydrogen. The experimental method used was therrnogravimetry under isothermal as well as non-isothermal conditions. The non-isothermal kinetics in the case of the reduction of MOO, to Moo2 has been modeled considering surface reaction as rate- controlling. In the case of the reduction of W02 to W a model was developed on the basis of the movement of the reaction front. The activation energies calculated on the basis of the models were in good agreement with those derived from isothermal experiments.

Jan 1, 1994

By Niloy K. Nath

Two layer sintering by charging green sinter mix with normal coke rate in the upper layer and reduced coke rate in the lower layer, can substantially reduce the coke rate and also improve the sinter quality by producing more uniform thermal profile through out the bed height. The two-layer sintering process have been analyzed by numerical simulation of the process by a detailed CFD based model, considering all the important phenomena like gas-solid reaction, melting and solidification, flow through porous bed, heat and mass transfer etc. Optimization techniques like genetic algorithm, differential evolution is then applied to evaluate the optimum coke rate in the two layers of the bed to produce the ideal thermal profile and melting fraction in the sinter bed for optimum sinter quality. Through this optimization method both high quality sinter with minimum return fines can be achieved along with reduced coke rate. Application of a genetic algorithm for this type of process optimization has several advantages over the traditional optimization techniques since it can identify global optimum condition and perform multi-objective optimization much easily for complex industrial process like iron ore sintering. Keywords: Two-layer Sintering, Iron Ore Sinter Quality, Ergun's Equation, Gas-solid reaction, Melting Fraction, Multi Objective Optimization, Pareto Set, Genetic Algorithm

Jan 1, 2003

By Tsutomu Yamamura

The electrolytic reduction mechanism of rare-earth chlorides such as LaCl3, CeCl3, NdCl3, ` SmCl3 and DyCl3 in alkali chloride baths has been investigated in NaCl, KCI and eutectic LiCI- KCI by means of electrochemical transient methods. The thermodynamic behaviors of rare-earth containing species have been discussed in the frame of Electrode potential - P02- diagram. Low current efficiency found in the case of Nd electro-winning has been attributed to the dissolution of Nd into the bath. The analyses of electrochemical measurement required the elucidation of the effects of the factors such as under-potential deposition, metal dissolution, moisture and oxygen partial pressure.

Jan 1, 2003

By Giuseppe Granata

An innovative process using titanium tetrachloride (TiCl4) gas as reactant has shown successfully to obtain titanium through electro-winning of TiCl2 formed in-situ on titanium cathode. The process involves a continuous feed of TiCl4 gas reacting onto a titanium cathode immersed in a molten salt (NaCl-KCl), whereby in-situ formation of titanium dichloride (TiCl2) through a disproportion reaction. Simultaneously, the TiCl2, thus in-situ formed in the molten salt media, has been reacted into chlorine gas and titanium, the latest electrodeposited on the titanium cathode by electrowinning. The reaction kinetic of this innovative process was investigated in terms of TiCl2 in-situ formation rate and galvanostatic electrodeposition rate, where, in particular, the effect of operating variables such as TiCl4 partial pressure and flow rate, as well as temperature and galvanic potential applied was investigated.

Jan 1, 2014

By Andriy Burbelko, Daniel Gurgul, Wojciech Kapturkiewicz, Marcin Gómy

"The mathematical model of the globular eutectic solidification in 2D was designed. The proposed model is based on the Cellular Automaton Finite Differences (CA-FD) calculation method. The model has been used for studies of the primary austenite and of globular eutectic grains growth during the ductile iron solidification in the thin wall casting. The model mentioned above takes into account, among other things, non-uniform temperature distribution in the casting wall cross-section, kinetics of the austenite and graphite grains nucleation, solute diffusion and non-equilibrium nature of the interphase boundary migration.Some aspects of stochastic nature of the solidification processes are taken into account. The results of the CA solidification modeling have been shown, that differences between cooling curves obtained in the same conditions of the casting solidification may be a result of the stochastic nature of the grain nucleation.The results of modeling were compared with the experimental microstructure. The model is well worked for thin walled ductile iron casting, for fast solidification process.IntroductionNodular graphite cast iron, also known as ductile iron (DI), has major applications in critical engineering parts due to its mechanical properties and castability. The mechanical and physical properties of this material depend on the shape and number of the graphite grains andmicrostructure of the metallic matrix.Solidification of DI was a subject of many computer modeling programs described in literature [ 1-5], in which the stationary conditions of carbon diffusion in austenite is pre-assumed. Recently, a tendency for production of thin-walled castings has been observed [ 6-8]. In this technology, the process of the fast solidification may be very far from equilibrium and steadystate conditions [9].The purpose of the present work is a two-dimension model development for simulation of the DI structure formation during the solidification in the condition of non steady-state temperature and diffusion fields in the thin-wall casting.Model of process The CA-FD is one of the known methods of the simulation ofmicrostructure formation during the solidification [ 10, 11]. In the CA microstructure modeling the outer grain shape is the result of the simulation and does not superimposed beforehand. The model development for a onephase microstructure evolution is a subject of the numerous researches [12 -23]. Model of the eutectic solidification of DI in the uniform temperature field and superimposed cooling rate is known [24]."

Jan 1, 2013

By Suzanne Young

The effect of LiF additions on liqt.1id1.:1s temperature and electrical conductivity over a wide range of cryolite bath ratios (1.0 to 1.5 weight ratio) was investigated. Results did not agree with multi-regression equations reported by Dewing and Choudhary over the entire region. New regression equations were developed. Reasons? are given for the differences. The models are used to discuss the economic implications of LiF additions to Hali cell electrolytes.

Jan 1, 1985

By Donna Guillen, Matthew Lehar, Sebastian Freund, Jennifer Jackson, Helge Klockow

"Research and development is currently underway to design an Organic Rankine Cycle (ORC) system with the evaporator placed directly in the hot exhaust stream produced by a gas turbine (GT). ORCs can be used to generate electricity from heat that would otherwise be wasted, thus producing carbon-free energy. In conventional ORC configurations, an intermediate oil loop is used to separate the hot gas from the flammable working fluid. The goal of this research effort is to improve cycle efficiency and cost by eliminating the pumps, heat exchangers and all other added cost and complexity of the additional heat transfer loop by developing an evaporator that resides in the waste heat stream. Direct evaporation – although simpler and less expensive to implement than indirect evaporation of the working fluid – has historically been avoided due to a number of technical challenges imposed by the limitations of the working fluid. The high temperature of the hot exhaust gas may cause decomposition of the organic working fluid and safety is a major concern due to the high flammability of some of these working fluids. The research team has addressed these challenges and developed a new direct evaporator design that can reduce the ORC system cost by up to 15%, enabling the rapid adoption of ORCs for waste heat recovery. The ORC system is intended to integrate with the GT either as a retrofit or to be marketed as a single package, thus maintaining the manufacturer’s warranty.IntroductionWaste heat from turbines and engines used in industrial applications along with waste heat from industrial processes are exceptionally abundant sources of energy. If even a fraction of this waste heat could be economically converted to useful electricity, it would have a tangible and very positive impact on the economic health, energy consumption, and carbon emissions in the U.S. manufacturing sector. Land-based gas turbines are used in a broad range of applications to produce both shaft and electrical power. Most commonly known for generating electricity either as peaking units or as base load units, they are also used to directly drive pumps, compressors or other machinery requiring shaft power. Simple cycle gas turbines have the advantage of a short startup time relative to coal-fired and nuclear units, however, they incur a significant penalty on their efficiency. Large frame gas turbines usually are combined with bottoming steam-based Rankine cycles to increase the overall efficiency of the system and thereby improve their cost performance. Small-frame gas turbines with exhaust temperatures around 500°C could in principle benefit from steam bottoming cycles, but rarely use them in practice because of the high capital cost of the steam system. Particularly for base load small frame gas turbines, akin to those used in pipeline applications, an increase in efficiency is highly desirable."

Jan 1, 2011

By Pinakin C. Chaubal

Today?s steel industry is in a vibrant and resurgent mode. This transformation has been in the making for some time now. Over the last few decades, the industry was steadily transforming itself into becoming a high tech industry. New technology was adopted, efficiencies were enhanced, lean manufacturing concepts were brought in and a strong customer focus was developed. Today?s mills employ sophisticated instrumentation, computerized monitoring, on-line smart systems etc. driving processes that are producing at rates of many tons/minute. All this is not possible without judiciously using the latest available technologies in various fields and developing a more sophisticated work force. Prof. Sohn has been a pioneer in driving the concept of process engineering in process metallurgy. In this paper the focus is on some aspects of process engineering ? primarily process modeling - as applied to iron and steelmaking processes. Examples are shown to demonstrate how problems have been addressed. Some thoughts on future directions are presented.

Jan 1, 2006

By A. D. Neuman, C. C. Davis, M. R. Lopez, A. C. Martinez, T. A. Nothwang, F. G. Hampel, S. L. Voit

"One of the thrust areas for the Global Nuclear Energy Partnership (GNEP) program is the development of actinide bearing fuels for transmutation in a fast reactor. Mixed Oxide (MOX) fuel has an extensive fast reactor irradiation history and thus is being considered for use as a baseline composition from which minor actinides can be incorporated for use as a transmutation fuel. The current study involves characterization of precursor powders and pellets destined for the Advanced Test Reactor in Idaho. These pellets will have three compositions: one standard MOX composition, (U0.80Pu0.20)O1.98, and two compositions of minor actinide mixed oxide (MAMOX) with oxygen to metal ratios (O/M) of (U0.75Pu0.20Am0.03Np0.02)O1.98 and (U0.75Pu0.20Am0.03Np0.02)O1.95. The precursor powders were characterized using a field emission gun scanning electron microscope (FEG-SEM) to determine particle morphology, size, and size distribution. An electron probe microanalyzer (EPMA) was used to characterize element distributions in the pellets.IntroductionThe fundamental purpose of GNEP is to enable a fuel recycling partnership between member nations. The customer nations utilize the fuel for electricity generation provided by and subsequently recycled by the supplier nation. The supplier nation recycles the actinide constituents, mainly uranium and plutonium, in advanced nuclear power reactors, and thus reducing waste volumes [1, 2]. Nuclear materials are strictly controlled through the International Atomic Energy Agency. One of the thrust areas supported by the GNEP program is the development of actinide bearing fuels for transmutation in a fast reactor under the U.S. Advanced Fuel Cycle Initiative (AFCI) in order to transmute long-lived transuranic actinide isotopes into shorter-lived fission products [3].MOX fuel has an extensive fast reactor irradiation history and thus is being considered for use as a baseline composition into which minor actinides can be incorporated for use as a transmutation fuel [4]. Irradiation performance data on oxide fuels with high concentrations of minor actinides is limited, which has prompted this study. This paper discusses the characterization results of precursor powders and pellets prepared for the Advanced Test Reactor in Idaho to determine the effects of including minor actinides in the fuel, and addresses two fuel test matrices proposed by Hilton et al. [3]. The pellets will have three compositions: one standard MOX composition, (U0.80Pu0.20)O1.98, and two compositions of MA-MOX with O/M of (U0.75Pu0.20Am0.03Np0.02)O1.98 and (U0.75Pu0.20Am0.03Np0.02)O1.95. The precursor powders, uranium oxide (depleted, DUO2 and highly enriched, HEUO2), neptunium oxide, NpO2, americium oxide, AmO2, and plutonium oxide, PuO2, were characterized using a FEG-SEM for particle morphology, size, and size distribution. The morphology of the actinide powders was studied in the areas of flowability and porosity in order to predict manufacturability. The MOX pellets were characterized using an EPMA in order to determine impurity levels and locations."

Jan 1, 2008

By M. Vondersaar, B. Bulnes

Quemetco, Inc.,. as a subsidiary of RSR Corporation, operates one of RSR's three secondary lead smelters in the City of Industry, California, next to a residential area within Los Angeles County. The Reverberatory furnace serves as the main reactor for melting lead grid and paste recovered by the battery crushing system. Feed material is introduced via screw conveyor after drying in an upstream rotary kiln. Slag produced by the Reverb flows directly to an electric arc furnace. Products from this one-pass furnace system consist of soft lead bullion from the reverb, hard lead bullion from the arc furnace, and a non-hazardous slag from the arc furnace. Furnace bullion is processed into finished product in a six-kettle refinery. An overview ·of plant operations is presented. Where applicable, references will be made to changes that have taken place during the last decade.

Jan 1, 2000

By J. D. Miller

Air-sparged hydrocyclone (ASH) flotation is a high-capacity flotation technology originally developed in the Department of Metallurgical Engineering at the University of Utah for processing mineral resources. However, the technology has been found to be useful in industrial waste processing, in the recycle of secondary resources, and in remediation of environmental problems. For example, areas in which the ASH technology is expected to have potential application include cleaning of waste coal fines, air stripping to remove volatile organics from drinking and process water, water disinfection by ozone or chlorine sparging, dispersed oil removal from water, and contaminated soil remediation. Recently, the ASH has been studied extensively for deinking flotation in the wastepaper recycling industry and has been shown to have excellent efficiency/capacity. In fact, a 20-million-dollar plant has been in operation since June 1992. The ASH technology can provide a specific capacity hundreds of times more than that which can be achieved with conventional flotation equipment and in certain instances is expected to provide superior separation efficiencies when compared to other technologies. The design and principles of ASH flotation are described. Experimental data for fine coal flotation, volatile organics stripping, and deinking flotation for paper recycle are presented and discussed. Finally, other potential areas of application for environmental technology are considered.

Jan 1, 1993

By J. E. Allen

The trend in refractory technology for the copper and nickel industries has been to higher quality raw materials and improved processing technology. These changes have been dictated by the changes in pyrometallurgical processes in these industries. For example the introduction of flash smelting, reaction type smelting and auxiliary slag cleaning furnaces havedemanded better refractories materials. Extensive field applications and improved laboratory testing procedures have helped make this transition possible. Changes in refractory technology, primarily in basic refractories, are followed from the late fifties to the present and into the future.

Jan 1, 1994

By Yongzhong Xiao, Tiejun Chun, Jian Pan, Deqing Zhu

"An innovative process of reverse floatation-direct reduction-low intensity magnetic separation was developed to effectively beneficiate the superfine run-of-mine (ROM) ore mined from Hunan Province, China. Mineralogy was measured that the ROM ore is of superfine low grade hematite ore type, assaying 27.2wt%Fetotal and with main valuable minerals of hematite occurring at size between 3 to 5µm. The upgrading results show that the final iron concentrate, assaying 88.3wt%Fe total and 94.5% metallization degree was obtained at an overall iron recovery of 69.9% under the following conditions: rough concentration by grinding of ROM up to 88.7% passing 0.074 mm and reverse flotation at pH=9.4, 100 g/t starch and 200 g/t dodecylamine (DDA), and coal reducing the rough concentrate pellets containing 12% calcium containing complex additive at 1200 oC for 120 min, and finally magnetic separation of the reduced pellets by grinding up to 89.2% passing 0.043 mm at 0.08 T field intensity.IntroductionWith the rapid development of iron and steel industry in China, there has been a soaring demand for iron ores in the past decade. The imports of iron ores have increased from 148 million ton in 2003 to 628 million ton in 2009 [1]. Iron making industries increasingly demand for high grade raw materials to improve product quality and reduce operation cost. However, availability of high grade natural ores is limited and enrichment of lower grade ores is necessary to meet the demand. Therefore, large quantities of superfine low grade iron resources are necessary to utilize in China at the moment."

Jan 1, 2011

By H. Itou, J. M. Toguri, T. Takasu

"Marangoni convection has a large effect on materials processing since it remarkably enhances heat and mass transport near a free interface. To have a better understanding of the behavior of Marangoni convection in molten salts, observation and calculation of the thermal convection in a column held between a pair of Pt disks (2mm in diameter) fixed to hot thermocouples, were carried out.Calculated flow patterns and absolute values of fluid velocity agreed well with the observed results. When the temperatures of both disks were set equal and the height of liquid column was 2.4mm, four vortexes were generated on the longitudinal plane with a typical velocity of 15mm/s . From the calculated isothermal lines, the behavior of the enhanced heat transport was obvious; fluid heated at the disks was conveyed to the free surface and the cooled fluid at the surface was conveyed to the inner region. Increase in the height of column and/or increase in the absolute value of applied temperature difference lead to increase in fluid velocity lineally in this calculation range.IntroductionIn the processing of many materials, fluid flow of melts has a large effect on refining capabilities and on the characteristics of the produced material. Marangoni convection is generated when a spatial gradient of interfacial tension exists on the free interface due to differences in temperature and/or concentration. This promotes heat and mass transfer locally near the interface.For example, Marangoni convection which are created following the dissolution of interfacially active materials, increases the local corrosion rate of refractories (1-3). In absorption and discharge of oxygen and/or nitrogen in a molten metal, the effective reaction rate of the gas components through the gas-liquid interface increases (4-7). Also in crystal growth, the distribution of defects and impurities in the crystal is affected and this can alter its quality (8-11 ). The temperature distribution is also affected and can greatly change the productivity. For these reasons, the effectiveness of Marangoni convection in refining should be quantitatively clarified and its control should be better understood."

Jan 1, 1997

By T. -M. Guo, M. J. Braun

"This paper presents an experimental and numerical study of melt flow near the solid-liquid interface and its effect on the interface curvature in a horizontal unidirectional solidification system with succinonitrile. Melt flow is introduced by increasing the ampoule channel thickness. Visualization techniques are employed to observe the flow field and the solid-liquid interface curvature. A numerical model is also developed to simulate the heat transfer, melt flow and phase change in the system. Quantitative information on the flow and temperature fields is generated. A good agreement is achieved between the experimental observations and model predictions. The results could be used for the study of the effect of the melt flow on interface morphology during solidification.IntroductionClassic unidirectional solidification experiments of transparent alloys are conducted with thin film samples sandwiched between two glass slides to investigate the development of interface morphology during solidification [1]. Samples with small channel thickness are usually used to suppress any melt flow due to natural convection and solidification in the channel would then be in the diffusive regime so that the solidification theory can be significantly simplified [2, 3]. Effects of melt flow, in particular due to natural convection, on solidification have also been studied extensively in those systems with large geometrical dimensions [4-6]. These studies indicate a strong effect of the melt flow on interface curvature during solidification [5, 6]. Only limited efforts were made to address the effect of the melt flow on interface morphology in horizontal unidirectional solidification, in particular for the cases when the channel thickness is not thin enough to suppress completely the natural convection [7]."

Jan 1, 2004