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By Joner Oliveira Alves

The aim of this work was to study the use of steelmaking slag as raw material to the production of rock wool and glass wool. Firstly, the chemical composition of the slag was analyzed. These results were used to infer the amount of additives to assemble the charge for the experiments. A laboratory-scale electric furnace was used to melt the mixtures used as charge. The melt material were turned into a water filled recipient, this process was performed in order to impose a fast freezing that is a characteristic of mineral wool production. Finally, with the rest of the melt material it was performed the Herty Viscosity Test. Samples of the produced material were characterized by different analyses. The results found in this research may lead to a technological innovation, because they indicate that the use of steelmaking slag to produce rock wool and glass wool is possible.

Jan 1, 2009

By Ragnhild Aune

In fire refining of copper, the affinities of various impurity elements on dissolved oxygen is of great significance. Further, in the design of oxygen probes in liquid copper, the influence of solute interactions on the activity of oxygen need to be considered in order to evaluate the oxygen concentration in molten copper. The present paper presents a series of measurements of the activities of oxygen in liquid Cu-M-o alloys (where M stands for Mn, Zn, As, Se or Te) carried out by the present group employing the solid electrolyte galvanic cell technique. Extreme care was taken to control the oxygen potentials in the inert gas atmosphere, and to keep the oxygen levels very low in the molten metal. The oxygen content was determined by analysis of the samples taken out from the melt. The results obtained showed that Mn has a strong negative influence on the activity coefficient of oxygen in liquid copper. A similar, but less prominent effect was observed in the case of Zn. Arsenic had no influence on the activity of oxygen in Cu (liq.). Se and Te had slight negative effect on oxygen activities in copper at XO > 10-5, while at lower oxygen levels the interaction coefficients were found to be positive. The results obtained were compared with empirical models for the calculation of interaction coefficients available in literature.

Jan 1, 2003

By S. P. Song

A computational methodology based on the coupled finite element and boundary methods is developed to predict the free surface shapes of electrically conducting liquids supported by the electromagnetic field. The work is an extension of our previous FEIBE model for induction calculations. The free surface algorithm is developed using the Weighted Residual Method, the very same used for nonlinear finite element formulation. This allows the treatment of field computation and free surface prediction in the same manner, thus making easier the formulation of the magnetically-supported free surface problems. Like other nonlinear algorithms, the boundary/finite element free surface scheme is also iterative owing to the fact that free surface shapes are unknown a priori. But the numerical scheme is robust and efficient and is capable of handling rather complex free surface deformations. Computational algorithms will be given and are tested by comparing with other solutions whenever available. Computed results of magnetically-supported free surface shapes are presented for magnetic levitation under microgravity and floating zone refining processes under normal gravity.

Jan 1, 1996

By Michael Zinigrad

The quality of metallic materials depends on their composition and structure and these are determined by various physico-chemical and technological factors. To effectively prepare materials with required composition, structure and properties it is necessary to carry out a research in two parallel directions: Comprehensive analysis of thermodynamics, kinetics and mechanisms of the processes taking place at the solid-liquid-gaseous phase interface during welding processes and development of mathematical models of the specific welding technologies. We have developed unique method of mathematical modeling of phase interaction at high temperatures. This method allows us to build models taking into account the thermodynamic characteristics of the processes, the influence of the initial composition and temperature on the equilibrium state of the reactions, the kinetics of heterogeneous processes, the influence of the temperature, composition, hydrodynamic and thermal factors on the velocity of the chemical and diffusion processes. The model can be implemented in the optimization of various technological processes in welding, surfacing, casting as well as in manufacturing of steels and non-ferrous alloys, materials refining, alloying with special additives, removing of non-metallic inclusions.

Jan 1, 2003

By Michael Zinigrad

The quality of metallic materials depends on their composition and structure and these are determined by various physico-chemical and technological factors. To effectively prepare materials with required composition, structure and properties it is necessary to carry out a research in two parallel directions: Comprehensive analysis of thennodynamics, kineties and mechanisms of the processes taking place at the solid-liquid-gaseous phase interface during welding processes and development of mathematical models of the specific welding technologies. We have developed unique method of mathematical modeling of phase interaction at high temperatures. This method allows us to build models taking into account the thennodynamic characteristics of the processes, the influence of the initial composition and temperature on the equilibrium state of the reactions, the kinetics of heterogeneous processes, the influence of the temperature, composition, hydrodynamic and thennal factors on the velocity of the chemical and diffusion processes. The model can be implemented in the optimization of various technological processes in welding, surfacing, casting as well as in manufacturing of steels and non-ferrous alloys, materials refining, alloying with special additives, removing of non-metallic inclusions.

Jan 1, 2003

By Mehdi Asgharifar, Rouzbeh Sarrafi, Radovan Kovacevic

"The surface treatment of aluminum alloys using atmospheric-pressure of low intensity DC plasma arc discharge is investigated in terms of surface properties. With respect to the conventional surface treatment processes for aluminum alloys mostly based on chemical etching or sand blasting, this process is very environmentally friendly and cost-effective. The effect of two processing parameters, the current and the plasma torch scanning speed, on the surface morphology is studied by using a scanning electron microscope. The effects of cathode spots within the tested range of process parameters are determined, and the limiting factors of the process (such as surface cracking) are discussed. The topographical studies of the treated surfaces have suggested potential enhancement of surface properties for different applications, such as preparing surface for painting and adhesive bonding.IntroductionIn the last decade the aluminum alloys are finding broad applications in automotive industry. In order to successfully execute the joining process of aluminum alloys such as arc welding, laser welding, and adhesive bonding, there is a need to remove oxides for welding and texture the surface for bonding along the join line. A number of surface treatment techniques such as chemical etching, sand blasting, and plasma treatment have been used by industry. It is shown [1] that plasma surface treatment is characterized as environmentally friendly, lower cost, and easier to control process. Bogaerts et al. [1] mention that when an adequately high potential difference is applied between cathode and anode, electrons are accelerated toward anode by an electric field coming in collision with gas atoms. The gas breaks down into positive ions and electrons, giving rise to gas discharge. The DC electrical discharges used in industrial plasma sources can be related to their location on the voltage-current curve as shown in Figure 1.It is generally believed that dark discharges other than coronas, and arc or torch plasmas are not very good candidates for surface treatment because oflow or high power density and active species flux. However, the glow discharge plasma is used for plasma surface treatment applications because of its proper power density and active-species flux [2]. Our objective is to investigate the feasibility of using low intensity DC plasma arc discharge as a surface treatment method without damaging the cathodic non-thermionic workpiece."

Jan 1, 2011

By A. J. Rigby

Current practices employing porous plugs to inject nitrogen into molten copper during primary smelting are described. Nitrogen stirring increases heat transfer to the bath, eliminates temperature stratifications, and improves efficiency during the steps of desulfurization and deoxidation. The opportunity to use porous plugs as the means to introduce reducing gases to deoxidize copper is also discussed. Previously reported laboratory results using porous plugs, which point to very high utilization efficiencies of hydrogen when used as the reducing gas, are again reviewed. Advances in the design of the porous plug, and the introduction of a system enabling external replacement of plugs is also discussed.

Jan 1, 1999

By Peter J. Koros

The current wave of interest in this topic is the result of increased use of titaniferous ores or ilmenite in blast furnace burdens for the purpose of repairing hearth damage. The titanium compounds that promote deposition of ?patching? materials in blast furnaces are the cause of downstream problems in the steelmaking shops. Steelmakers historically have objected to significant amounts of titanium in hot metal (>0.10 % Ti) for several reasons: 1) accretions caused by the TiC.TiN needles that float out of the iron as it cools in transit and in transfers make the accompanying slag sticky and crusty, causing problems in desulfurization and increasing time and Fe yield loss at the subsequent raking, 2) defensive measures have been taken in treatment, such as use of argon for carrier gas, but without technical rationale for this approach, 3) difficulty in removal of the ladle slag by the raker, with subsequent sulfur addition to the vessel charge, and 4) transfer into the BOF and/or formation of a very corrosive TiO2 containing acid slag during the early part of the BOF blow which, in addition to causing lining damage, results in loss of sulfur removal capability by the vessel slag. Based on a conceptual analysis of the metal-slag-atmosphere interactions during transfer ladle desulfurization treatment, a mechanism is postulated for the apparent effectiveness of the use of argon in reducing the deleterious effect of titanium and an alternate technique, possibly more effective, is proposed. As probably the use of argon causes increased exposure to atmospheric oxidation of the titanium carbonitrides contained in the ladle slag, the same benefit can be obtained by use of either oxygen or an air blast to oxidize the noxious reaction compounds. Validity of the concept has been demonstrated in a pilot plant setting. These issues, and related effects on testing the hot metal, are examined in detail with reference to the literature and plant and laboratory experience.

Jan 1, 2006

By Varadarajan Seshadri

Geometallurgical characterization of iron ore which is a raw material for Iron making as in the case of charcoal blast furnaces operating in Brazil or for production of agglomerates such as iron ore sinter which serves as burden material for blast furnces of high productivity or pellets extensively used in the direct reduction processes all over the world in the iron and steel industry. Selection of proper raw material after due characterization should lead to an improvement of the productivity of the respective processes The usual classification of quality of iron ore is uniquely based on chemical analysis, granulometric and physical parameters. However not much emphasis has been given to the structural characteristics which also are important in the processes. Different typological categories of Brazilian iron ores have been used in the characterization . For instance, several kinds of hematite crystals like specularite, martite and microgranular hematite, etc with variable crystal sizes are found in the different ore types. They are also composed of different of fabrics and types of accessorial mineralogical constituents and have different porosities, pore diameters, etc which influence the cold and the hot agglomeration stages of the ore fines, and also chracteristics such as reducibility, decrepitation etc, important for assessment of quality of iron ores. . The first step for attaining a good characterization of ores is to know in detail about the structure of the deposit, shape of the body, types of iron ores and their distribution. This requires a geological-structural study and the mapping of the bodies using mineralogical criteria for typological classification of ores. followed by structural characterization of materials in stages of mining, comminution, screening and concentration processes. In this contribution a geometallurgical approach for quality control of Brazilian iron ores for sintering and pelletizing processes is highligted.

Jan 1, 2006

By Fang Wu

The paper designs an extraction flow for the total recovery of nickel and cobalt and removing magnesium simultaneously from the cadthodic materials of the spent hydrogen-nickel and cadmium-nickel batteries. The separation of Co, Ni and Mg though P507 extraction .The extraction equilibrium pH is 4.5~5.0, ßNi/Co is 140~180, and ß Ni/Mg is 20~25; nickel and magnesium are scrubbed in two steps, in which the equilibrium pH of nickel and magnesium scrubbing is controlled at 5.0±0.1 and 4.4±0.1 respectively. The stepwise scrubbing technique is adopted to remove 94.5% of magnesium and to recover 99.45% of nickel and 95.35% of cobalt. During the integrated extraction and precipitation process the total recovery fraction of nickel and cobalt are 99.99% and 99.95%, and the recovery fraction of magnesium is 94.02%.The recovered NiSO4 and CoSO4 solution are enriched and crystallized.

Jan 1, 2009

By H. Kaffash

Ferromanganese is a ferroalloy with high manganese content which finds many uses for example as deoxidizer in steelmaking industry. However, there is very little data on the dissolution rate of carbonaceous materials in Mn containing metals. In this paper, the kinetic analysis of carburization reactions is investigated for Mn–Fe alloys. Dissolution rate of graphite in pure iron and four different alloys with 10 wt%, 40 wt%, 60 wt% and 85 wt% manganese at 1823 K was studied. Results showed that the dissolution rate of carbon from graphite increased with increasing time for all alloys. The dissolution rate constant increased with the increasing manganese content from 6.5 × 10−3 cm/s for 0%Mn to 23.6 × 10−3 cm/s for 85%Mn.

By Tracie Zoeller, G. Paul Neitzel, Jr. Sanders

"As-cast aluminum alloy microstructures are highly segregated. Coring occurs when solute is rejected during solidification resulting in a non-uniform solute distribution across the dendrite arms. Furthermore, coarse constituent phases are formed in the interdendritic channels as a result of coring. These constituents are either soluble or insoluble and can form from the major solute elements, or the impurity elements iron and silicon. The dissolution of these constituents, or precipitates, is an important consideration in determining the microstructural evolution of an alloy. The properties of an alloy are significantly affected by the morphology of the precipitates. Precipitates can be either beneficial or detrimental to the properties of the alloy. Regardless of the nature of the precipitates present, it is useful to understand the dissolution process. A diffusion-limited dissolution model for planar precipitates is presented and compared to an analytical solution and to models in the literature. Experimental data for the dissolution of AhCu precipitates in a dilute alloy are compared to the proposed model, and found to have good agreement.IntroductionDuring the processing of precipitation hardening alloys, beginning with the solidification step and ending with the final solution heat treatment step, there are a variety of particles that form. Some of these particles must be dissolved and solute redistributed and re-precipitated in a more homogeneous distribution than as it first appears in the as-cast microstructure. The particles can be classified by size as microstructure develops during processing. Coarse particles that form during solidification can either be soluble, partially soluble or insoluble. These particles can be the result of coring of the major solute elements as well as the limited solubility of elements such as iron and silicon. Iron and silicon can combine with the major solute elements such as copper in 2xxx alloys forming coarse phases often referred to as constituents. Figure l(a) shows the as cast microstructure with the constituent phases, Al2Cu and the insoluble phases containing Al-Fe-Mn-Cu-Si [7]. During preheating the soluble phases such as AhCu that were formed by eutectic decomposition must be taken back into solution, whereas the insoluble phases remain essentially unchanged by most thermal operations. Figure l(b) and (c) show some of these constituents after subsequent preheating steps. In Figure l(b), AhCu platelets are shown and in Figure l(c) the remnants of the AhCu phase are noticeable, along with Mn-bearing dispersoid phases. Reduction in the volume fraction and size of these phases improves the ductility and fracture toughness as well as reducing the inhomogeneities that occur during coring. Also adjacent to the dendrite arm boundaries are smaller AhCu phases that precipitate by a solid-state transformation on cooling to room temperature."

Jan 1, 2004

By Toshiyuki Hashida, Victor M. Lopez-Hirata

"Small-punch tests and determination of fracture toughness JIC were conducted at 4 and 77 K on new cryogenic JN1, JJ1 and JK2 austenitic stainless steels, after isothermal aging. Equivalent fracture strain ?qf determined by measuring the reduction of thickness in the small-punch test specimen. A linear dependence of JIC on ?qf was found in these new materials. Regression analysis of experimental data produced the following linear relation JIC = 1304.1 ?qf + 8.09 [kJm-2]. An analysis of present work relation was pursued on the basis of material properties and evaluation method of he. Results showed that the slope value has a strong dependence on material yield strength and JIC evaluation method. This linear relation is useful for the evaluation of fracture toughness JIC, measuring the equivalent fracture strain ?qf by means of small-punch test. Thus it can be useful for assessing the degradation of fracture toughness in small areas such as, the heat-affected zone in welded components.IntroductionCryogenic structural materials for superconducting magnets of fusion nuclear reactor are required to possess a good combination of strength and toughness. The mechanical properties are required beyond the capability of conventional austenitic stainless steels [1]. New cryogenic JN1, JJ1 and JK2 austenitic stainless steels were developed by the Japan Atomic Energy Research Institute (JAERI) [1]. The structure of superconducting magnets is constructed by welding of 200 = thick plates of these steels, which are solution treated at high temperatures and then water-quenched to avoid intergranular precipitation. However, the welding process involves heating and cooling [2], which cause microstructural changes in both base metal and weld. In this heterogeneous microstructure, it is important to estimate the fracture toughness of these materials at cryogenic temperatures. Therefore, it is necessary to evaluate the effect of aging process on the fracture toughness behavior of these new steels. To determine the cryogenic fracture toughness, the elastic-plastic JIC value has been co=only used [2]; however, the specimen size is much larger than heat-affected zones in welded components. Small-punch (SP) testing method, employing miniature specimens, has permitted to evaluate the fracture toughness behavior at different temperatures in different nuclear reactor materials [3,4]. Mao et al. [5,6] and Misawa et al. [7] found a linear relation between JIC value and equivalent fracture strain ?qf, determined by SP method in non-ferrous alloys and ferritic steels at room temperature and austenitic stainless steels at 4 and 77 K, respectively. So that, this kind of correlation would be very useful to assess the fracture toughness JICe values by means of SP test in small zones of welded components."

Jan 1, 2012

By J. H. Puffer

The copper mineralization of the Mesozoic Passaic Formation of New Jersey is typical of copper deposits in eastern North American Mesozoic sediments. Most such deposits are located at the base of the first of several basalt flows that are interbedded with continental, red-bed sediments. The copper mineralization is similar in most respects to that of the Keweenawan Basalts of the Lake Superior area. The first basaltic flow units of the eastern North American Mesozoic basins, and the Keweenawan Basalts, are continental quartz tholeiites of similar chemical composition and copper contents. The copper minerals and associated zeolite facies metamorphic mineral assemblages of these two rock units are also approximately the same. Stoiber and Davidson (1959) suggested that Keweenawan copper was mobilized and concentrated during metamorphism. The evidence pertaining to the Mesozoic copper deposits of New Jersey is consistent with such an interpretation and also with DeVore's (1955) suggestion that ore fluids commonly arise as a result of the mobility of metals under metamorphic conditions. There is additional evidence that final metamorphic concentration of Mesozoic copper was preceded by an initial stage of hydrothermal precipitation related to fluids emitted by basaltic magma.

Jan 1, 1987

By G. Granata

In this work, we studied the recovery of copper from AMD by cementation with iron powder. To control the size of copper particles within the nanoscale range, we tested the use of the anionic surfactant sodium dodecyl sulfate (SDS). We tested three concentration levels (0.2, 0.4 and 0.6 M) and temperatures (25, 50 and 75 °C). The activation energy of cementation was also assessed by fitting the experimental data with the Arrhenius equation. Under all investigated conditions, the cementation reaction was found to be a diffusion-controlled process. Without surfactant, the activation energy was 19.9 kJ/mol. In the presence of SDS the activation energy increased up to about 35 kJ/mol. With or without SDS, the particle size of the copper product was strongly affected by the cementation temperature. Without SDS, the cemented product aggregated into micro-sized clusters of about 15 μm at 25 °C, 2–3 μm at 50 °C and 1 μm at 75 °C. The addition of SDS resulted in a dramatic decrease of copper particle size up down to the nanoscale range. Under the best operating conditions, the particle size of copper was <100 nm.

By Chonghe Li, Xionggang Lu, Wei Xiao, Xingli Zou, Weizhong Ding

The reduction degree and rate of the initial ilmenite concentrate and pre-oxidation samples by hydrogen were investigated by using thermogravimetric analysis system. H2-TPR was used to detected reduction properties of the pre-oxidation products which were oxidized at different temperatures. The phase transformations and micromorphology changes during pre-oxidation and hydrogen reduction were identified by XRD and SEM. The FeTiO3 was decomposed into TiO2 and Fe2O3 at the temperature below 900 oC. With the temperature rising, Fe2TiO5 was the only stable phase in high temperatures. The reduction of pre-oxidation ilmenite concentrate was faster than the natural sample, which was attributed to the micropores generated on the surface of ilmenite concentrate during oxidation. The main phases of the reduction product were metallic iron, ferrous pseuodbrookite.

Jan 1, 2014

By Ji-He Wei

Keywords: stainless steel, AOD refining, side and top combined blowing, mixing characteristics, water modeling The fluid mixing characteristics in the bath during the side and top combined blowing AOD (argon-oxygen decarburization) refining process of stainless steel have preliminarily been investigated on a water model unit of a 120 t AOD converter. The geometric similarity ratio between the model and its prototype (including the side tuyeres and the top lances) was 1:4. On the basis of the theoretical calculations for the parameters of the gas streams in the side tuyeres and the top lances, the gas blowing rates used for the model have more reasonably been determined. The influence of the tuyere number and position arrangement, and the gas flow rates for side and top blowing on the characteristics has been examined. The results demonstrated that the liquid in the bath underwent vigorous circulatory motion during gas blowing, without obvious dead zone in the bath, resulting in a well mixing effectiveness. The gas flow rate of the main tuyere had a governing role on the characteristics, a suitable increase in the gas flow rate of the subtuyere could improve mixing efficiency, and the gas jet from top lance could make the mixing time prolong. Corresponding to the oxygen top blowing rate specified by the technology, a roughly equivalent and good mixing effectiveness could be reached by using six side tuyeres with an angle of 27 degrees between each tuyere, and five side tuyeres with an angular separation of 22.5 or 27 degrees between each tuyere. The relationships of the mixing time with the gas blowing rates of main-tuyeres and sub-tuyeres and top lance, the angle between each tuyere, and the tuyere number have been obtained.

Jan 1, 2005

By Jean-Christophe Gebelin, Mark Jolly, Samantha Jones

"The de-waxing process in investment casting is truly a black art which is carried out in a black hole - the autoclave. The process involves exposing wax, coated by a porous ceramic shell, to steam at a pressure of 10 bar and a temperature of about 180°C. The processes which then occur are truly multi-media and multi-physics. Steam condenses in the porous ceramic, wax melts and flows, the shells expand and sometimes crack. Why the shells crack is one of the most difficult questions asked in the industry.Modelling and validating the de-waxing process is not simple. The IRC at the University of Birmingham is attempting to model this process using Physica+ a code developed in the UK. This paper will present the latest results in this attempt to model one of the casting industries most intractable problems.IntroductionThe de-waxing process using an autoclave involves the following physical phenomena:· Flow of the steam in the autoclave;· Heat transfer from the steam to the wax, possibly through the shell;· Melting and flow of the wax.At the same time, other phenomena may occur, such as the flow of the steam through the shell, the condensation of the steam on the shell surface and on the wax pattern surface, the flow of wax the through the shell, etc ...This shows how complex the de-waxing process is from a physical point of view. The main defect that appears during this process is the cracking of the shell. Previous modelling work carried out by Snow [1] has shown that it is possible to predict the stress in the shell, making numerous assumptions. In this paper, the modelling to predict the state of stress in the shell that is currently in development at the University of Birmingham is presented together with the presentation ofthe physical phenomena to model and the assumptions used. The parameters that are needed in such models will also be discussed, and some experimental work undertaken at the moment presented."

Jan 1, 2001

By C. Beckennann, C. Y. Wang

"Computer simulations of structural and compositional development in equiaxed dendritic alloy solidification are performed using a recently developed multi phase model. The model not only accounts for the transport phenomena occurring on the macroscopic (system) scale, but includes also the grain nucleation and growth mechanisms taking place at various microscopic length scales. In this paper, a numerical technique consisting of a fully implicit control-volume based finite difference method and a multiple time step scheme is developed for accurate and efficient simulations of both micro- and macro-phenomena. Sample numerical results are presented to reveal the effects of liquid now and crystal sedimentation on segregation and the final grain size distribution. In particular, the importance of the interplay between the dendrite microstructure and multiphase now patterns is shown.IntroductionIn recent years, modeling of equiaxed dendritic solidification without convection has experienced considerable progress (1,2]. Nucleation and growth kinetic laws have been coupled with transient heat conduction calculations to determine the solidification microstructure. However, modeling of equiaxed dendritic solidification with melt convection and solid movement has not been attempted so far, largely because of the complications associated with the transport of free equiaxed crystals in the melt. The gravity-induced transport of free crystals is fundamental to the development and extent of the equiaxed zone and also greatly affects the columnar to equiaxed transition. Another possible effect of crystal sedimentation or floatation is to cause severe macrosegregation as well as structural inhomogeneities. The only study available in the literature that accounts for both liquid convection and solid transport is by Ni and Beckermann (3], but deals with globulitic structures (as opposed to dendritic)"

Jan 1, 1994

By Zuhair A. Munir

"The use of self-propagating combustion reactions to synthesize metallic, ceramic, and composite materials is described. The limitation of this process because of the porous nature of its products is discussed. The formation of dense bodies through the simultaneous application of pressure is shown for a metal-matrix composite. The effect of an external electric field on the synthesis of ceramic and composites is described. The nature of the effect of the field on the mechanism of synthesis is analyzed theoretically and experimentally. The use of the self-propagating combustion to synthesize intermetallic thin films is presented for the Ni-Al and Ti-Al cases. The formation of functionally gradient materials (FGM) by centrifugally-assisted self-propagating high-temperature synthesis is described.IntroductionThe use of self-propagating combustion reactions for the synthesis of a large number of simple and complex materials has been described in numerous publications. These have been amply discussed in several review articles [1-4]. The many benefits of this method of materials synthesis are commonly examined in light of its most significant limitation: the porous nature of its products. The porosity in the products of self-propagating high-temperature synthesis (SHS) is an intrinsic characteristic of the process and its elimination has been the focus of numerous attempts. Various experimental methods have been used to accomplish this goal."

Jan 1, 1994