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By C. Burton Clark

The important role of the petrographic microscope in the petrology of refractories is discussed, based on 45 years of industrial experience by the author. Highlights of his career are used to illustrate improvements in equipment and techniques during the period. Two specific investigations are described which emphasize the interrelated use of the petrographic microscope with other instruments such as the x-ray diffractometer and scanning electron microscope. Emphasis is placed on the use of phase equilibrium diagrams for guidance in predicting and interpreting reactions that occur under non-equilibrium conditions in the manufacture and use of refractories.

Jan 1, 1982

By Lifeng Zhang

The transport of fluid, heat and particles (bubbles and solid inclusions) in flowing molten steel is investigated in steel refining ladles, the continuous casting tundish, continuous casting mold and strand, and steel ingot casting processes. Inclusion removal from the molten steel by flow transport and bubble flotation, and inclusion growth by collision and diffusion are discussed. Removal of impurity elements such as [C] and [O] during steel refining are reported.

Jan 1, 2006

By R. E. Sundell, S. M. Correa

"A mathematical model is developed for the fluid flow in tungsten-inert gas weld pools. The fluid is taken to be incompressible, viscous, electrically conducting, and confined within a pool of specified shape. The flow is driven by surface-tension gradient (thermocapillary), electromagnetic, and buoyancy forces generally in this order of importance. Analysis indicates that the electromagnetic field may be calculated a priori and so decoupled from the nonlinear fluid mechanics and heat-transfer problem. The resulting set of equations is solved numerically by a line relaxation process. Computational errors caused by truncation in finite-difference schemes and by inadequate grid distributions are considered. The model is used to study several cases of differing heat and current input to the pool with and without surfactant-induced thermocapillary forces. The principal conclusions are that the thermocapillary flow, when present, is dominant with surface velocities on the order of 1 m/s. The heat transfer, as deduced from isotherms within the pool, is crucially dependent on the flow. Also, flow velocities and weld-pool surface temperatures were measuredand agree well with the model.2. IntroductionThe requirements of improved control and of automation in the TIG (tungsten-inert gas) welding process have led to the development of mathematical models for the heat transfer to the workpiece. It is now widely recognized that the fluid flow in weld pools sufficiently distorts the conduction heat transfer pattern to warrant inclusion in a process model. The experiments of Woods and Milner (1), among others, demonstrated that TIG weld pools could be driven by the electromagnetic J x B body forces present, J being the current distribution and B the induced magnetic field. Atthey (2) calculated that in typical pools the buoyancy force was about an order of magnitude less important - despite the large temperature gradients present - and neglected it in a computational study of the magnetohydrodynamic (MHD) flow. This work also reviewed many earlier studies of MHD flow caused by a source of current at a fluid surface, including analytical studies by Shercliffe (3), Sozou (4), and Sozou and Pickering (5), and a numerical study by Andrews and Craine (6). These works establish the importance of the electromagnetic force in the weld-pool flow."

Jan 1, 1986

By Broggi Andrea

Condensates produced by SiO(g) and CO(g) have a crucial importance in silicon production. Condensation will follow the reactions 3 SiOðgÞ+COðgÞ→ 2 SiO2 + SiC and 2 SiO ðgÞ→Si+SiO2. Solid compounds generated during silicon production contain Si, SiO2 and SiC in different microstructures and amounts. In industrial systems, condensates limit the SiO(g) escape to the off-gas system. On the other hand, they can block the gas flowing from the high temperature zone, hence the necessity of studying an optimized condensation process. This review discusses SiO(g) condensation and its interaction with CO(g). The report gives an overview of the condensates found both at laboratory and at industrial scale. The two main compounds are the Si–SiO2 and the SiOx–SiC mixtures. The hypothesis on the mechanism of formation of SiC–SiOx condensates is presented through a wide selection of performed works. The advantages and disadvantages of the former experimental procedures are discussed.

By Do-Hyeong Kim, Jong-Jin Pak, Jung-Mock Jang, Min-Kyu Paek

"Thermodynamic relations among Mn, Al and N in liquid iron were studied by measuring the effect of Mn on the solubility product of AlN in liquid Fe-Mn-Al-N alloys in the temperature range from 1773 to 1873 K. The critical Al and N contents for AlN formation were determined by the metal-nitride-gas equilibration technique over wide ranges of melt composition and temperature. The effects of Mn on N solubility in Fe-Mn and Fe-Mn-Al melts containing Mn up to 26 mass% were separately determined in the same temperature range. The experimental results were thermodynamically analyzed using the Wagner's formalism to estimate the critical Al and N contents for the onset of A1N formation. The validity was checked by the observation of inclusion evolution in Fe-20%Mn-1.5%Al-0.6%C-0.3%Si-0.012%N melt during cooling and solidification.IntroductionRecently, high manganese steels such as Twinning Induced Plasticity (TWIP) steels have been developed as next generation steels because of their high formability as well as excellent strength and ductility.[1•2l In these steel grades, a large amount of Mn (15-20 mass%) and Al (1-2 mass%) are added to liquid steels, and such high Mn and Al concentration bring the great challenges to the steelmaking and casting processes. Mn significantly increases the N solubility in liquid iron and the AlN inclusions can be easily formed at such high Al concentrations due to high affinity of Al and Mn with N in liquid steels. Although the AlN inclusion is known to be a dominating and considered as a detrimental phase for the hot ductility of steels,l3l thermodynamics of AlN formation in high Mn-Al alloyed liquid steels was not well known.Moreover, the melting point of these steels decreases down to near 1623 K as increasing Mn content up to 20 mass%. However, most of thermodynamic data has been measured at the steelmaking temperature around 1873 K. Even at steelmaking temperature, there are huge scatters in thermodynamic interactions of Mn and Al on N in liquid iron. The nitrogen solubility in Fe-Mn alloy melts has been measured using the Sieverts' method[4l and the samplinij method[5-7J in the temperature range of 1813 to 1973 K. In the authors' recent study,[8•9 the N solubility in Fe-Al alloy melts was measured using the sampling method in the temperature range of 1823 to 1973 K. However, the simultaneous effect of Mn and Al at high concentrations on Nin liquid Fe-Mn-Al-N alloys is still not known. Also, there remains uncertainty about the temperature dependence of the interaction parameter of Mn on N in liquid Fe-Mn alloys. Therefore, it is worthwhile to check the temperature dependence of this parameter at a low temperature near the melting point of Fe-Mn alloys. There have been few studies on the characterization of non-metallic"

Jan 1, 2014

By Francis Vanbellen

Umicore Precious Metals Refining operates an integrated precious metals smelting and refining plant in Hoboken, Belgium. Once a smelter and refiner of complex concentrates, the plant today?s feed consists exclusively of industrial and consumer recycled products, making it the world?s largest recycling facility for precious metals. Unlike the fairy tale of the Frog Prince, it took much more than a princess? kiss to successfully realize this makeover. A completely renewed plant has been built over the past decade.

Jan 1, 2006

By W. R. Opie

Fundamentals of blast furnace smelting of low grade copper and precious metal scrap and residues are reviewed with emphasis on emission control, by-products produced, slag cleaning for high recovery of metal values and the evolution of an off-gas system to eliminate hydrocarbons that result from decomposition of plastics in the blast furnace- charge. Problems with tin, antimony and nickel in the smelter-refining cycle are discussed.

Jan 1, 1985

By Xuerong Wen

The oxidation behavior of TiAl3 intermetallics was investigated as a hnction of time at 1273K in pure dry oxygen. The oxidation experiments were carried out using TGA method. The oxidation scales were analyzed using SEM, EDS and X-ray diffraction methods. The structures of oxides formed at the different oxidation times were analyzed. The mechanism of oxidation of TiAl3 intermetallics was discussed.

Jan 1, 1998

By Jorge Alberto Soares Tenório, Romano Espinosa, Felipe Fardin Grillo, José Roberto de Oliveira, Denise Crocce

"The aim of this work was evaluation of the recovery of Zn and Fe of the EAFD added to the hot metal in the form of briquette at temperature of 1500°C. The EAFD was agglomerated by cold briquetting and introduced in the hot metal. This study utilized a bench-scale equipment to melt, during this process to kept a flow rate of inert gas above the bath. Were collected periodically metal samples and the samples were analyzed for determination of the content of total silicon and carbon by chemical analysis. Zinc oxide, zinc ferrite and other oxides were reduced and were volatized and collected by a cleaning system of dust (baghouse) located on top of the oven. More than 98% of iron were recovered from EAFD during the test. It was possible to produce a dust containing about 68% zinc by means of adding of EAFD.IntroductionIn the first semester of 2010, steel production was about 706 million tons, 27.9 % more than in the first half of 2009. Not a significantly increase if 2010 data is compared with the first semester of 2007 (only 7.2 % higher), before the world’s economic crises. Steel production is divided into two main routes. The first one, and most used, is the Basic Oxygen Furnace Process (BOF process), which in 2008 accounted for approximately 67.1 % of steel production. The second route is carried out in the Electric Arc Furnace (EAF) that in 2008 represented 30.6 % [1 ].Electric arc furnace dust (EAFD) is a solid waste generated during the steel making process. It is classi?ed according to NBR 10004 as dangerous solid waste-class I, because the elements Pb e Cd leach in water exceeding the maximum limits permitted by the NBR 10004 [2 ]."

Jan 1, 2012

By Patricio Ruz, Gabriel Riveros, Carolina Ramirez, Andrzej Warczok, Rober Treimer

"Continuous converting of copper matte produces slag with high cuprous oxide content. The corrosion of chrome-magnesite refractories with slag of high cuprous oxide content is a major problem. Properties of olivine type of slag make the slag very attractive for matte smelting and converting.Analysis of phenomena determining the slag infiltration into the porosity of a refractory and dissolution of refractory components in the slag allowed for better understanding of the mechanisms of refractory destruction.The results of laboratory scale tests of the olivine slag infiltration into open porosity and corrosion showed dominating effects of slag temperature and cuprous oxide content. The optical and X-ray examination of slag samples permitted the definition of the mechanism of formation of new phases and refractory deterioration. 71"

Jan 1, 2009

By Larry G. Twidwell, Jannette L. Chorney, Bryce D. Ruffier, Katelyn M. Lyons, Daniel W. Gaede, Ryan J. Foy, Jerome P. Downey

The Army Research Laboratory (ARL) has an interest in the recovery and processing of rare earth elements. At Montana Tech, elevated temperature chlorination of rare earth oxides is presently being investigated as a potential methods leading to the selective separation and recovery of rare earth elements from mineral ores and concentrates. After preliminary evaluation, ytterbium oxide was selected as a representative surrogate material for more extensive chlorination studies. Methods used to determine the conversion and recovery include X-ray diffraction (XRD) and inductively coupled plasma (ICP) analysis. These data have been used to establish and confirm process conditions that consistently yield high conversion efficiencies. Based on the promising results, further experimentation is underway to ascertain the metallurgical response of other rare earth oxides and carbonates to the roasting process. The end goal is to create a robust process for industrial application that has greater efficiency and reduced costs as compared to current practice.

Jan 1, 2015

By Tobias Dubberstein, Hans-Peter Heller

The viscosity of Fe-Cr-Mn-Ni TRIP/TWIP (Transformation Induced Plasticity, Twinning Induced Plasticity) steel with varied nickel content is investigated using a vibrating finger viscometer. The viscosity of the melt is calculated from the change in power input in the field coil by an immersed finger into the liquid steel to maintain a constant peak-to-peak amplitude of the sine wave of oscillator compared to the idle state. Nickel content in steel is varied from 3 wt% to 9 wt%. The dynamic viscosity (η) at 1600 °C for 3 wt% Ni is 3.73±0.14 mPas, for 6 wt% Ni 3.50±0.03 mPas, and for 9 wt% Ni 3.93±0.09 mPas. There is a kink from low to high nickel content in viscosity values of Fe-Cr-Mn-Ni alloys. This phenomenon can be explained by a change in coordination number in the melt, as reported for Fe-Ni binary system in literature. The availability of viscosity data delivers relevant input to model free fall atomization processes of FeCrMnNi alloys.

Jan 1, 2015

By Ryosuke O. Suzuki

A new cell concept for calciothermic reduction is proposed in which the titanium dioxide instead of TiCl4 is used as the raw material for reduction, Metallic calcium is needed as the reductant of a thermochemicaily stable oxide, such as TiO2. CaCl2, is selected as the solvent of Ca and simultaneously as the solvent of CaO. The reduction system consists of a single cell where both the reduction reaction and the electrolytic reaction for recovery of reducing agent coexist in the same molten CaCl2 bath. A few mol%Ca dissolves in the melt and gives the media a strong reducing power. Sufficiently deoxidized metallic titanium deposits and forms a slightly sintered granular sponge. Both mechanisms of the halide flux deoxidation and the electrochemical deoxidation work efficiently for these fine precipitates, The reducing agent is in situ recovered by electrolysis of CaO because the molten CaCl2 he a relatively large solubility for CaO Some cell designs and modifications are proposed for industrial applications.

Jan 1, 2003

By Shengli Wu, Mingyin Kou, Laixin Wang, Zhe Wang, Xinliang Liu

The sticking behavior of iron ores in the shaft furnace is one of the most important problems in the COREX melting progress, which directly influence the smooth operation and productivity of shaft furnace. Therefore, it is of great importance to study the sticking behavior of pellets in COREX shaft furnace. The results showed that porous metallic iron produced at the interface of pellets samples was the main reason for the sticking of pellets in the COREX shaft furnace. The SI (sticking index) and metallization rate increased with the reduction temperature and gas flow, and decreased with melting rate. However, the SI of pellets in the COREX shaft furnace could be decreased by the proper match of melting rate and reduction temperature, reduction temperature and gas flow, while the metallization rate of pellets were kept at a certain level. Furthermore, the matching of melting rate and reduction temperature was more effective than the matching of reduction temperature and gas flow.

Jan 1, 2016

The present work is mainly focused on developing intermetallic inert anodes for aluminum electrolysis. The anode alloy based on Al-Ti-Cu system was prepared by casting, followed by the application of a protective coating. Behaviour of corrosion and the passivation under anodic condition was characterized using the electrochemical and microscopic techniques. The results obtained clearly demonstrate that the oxide coating can provide good corrosion resistance via surface passivation of alloy anodes, rendering them inert in cryolite melt.

Jan 1, 2006

By Thomas P. Battle

Ilmenite (iron titanate) is the source of over 90% of all the titanium produced in the world today. At some point during production of titanium dioxide or titanium metal the iron impurity must be removed. Too often it becomes a waste instead of a product. DuPont and MINPRO have developed a solid-state process which separates the iron and titanium components of ilmenite into different high-purity powders, which can be separated using conventional mineral processing techniques. The main reactor in this process is a unique high-temperature ball mill, where the iron segregates from the ilmenite lattice with the assistance of catalytic quantities of He\. The results of lab, pilot plant, theoretical, and scale-up studies are presented and discussed.

Jan 1, 1996

By Xun An

Slag from an electric slag cleaning furnace was injected with methane and air mixtures to facilitate the recovery of copper and cobalt. The effects of methane-to-air ratio, gas flow rate and temperature on the reduction and metal separation were investigated. The results showed that over 90 percent copper and up to 60 percent cobalt could be recovered from the slag with a gas utilisation of around 70 percent, as calculated by thermodynamic simulation. Methane-to- air ratio was a major factor affecting the rate of reduction under the present experimental conditions. Further, injection of gaseous reductants greatly enhanced the coalescence and settling of entrained metal droplets. A reduction mechanism is proposed and the factors influencing the coalescence of copper droplets are discussed.

Jan 1, 1998

By James C. Barker

Recent investigations of a 55-km long trend of intrusive complexes on southern Prince of Wales Island have identified significant resources of Nb, Y, REE. U, Zr, and a host of potential by-product metals. The northwesterly trend comprises multi-phased sodic alkaline and peralkaline diorite, monzonite, syenite, and riebeckite granite. There are at least three significant deposit types recognized, two of which, 1) pegmatite dikes/vein-dikes that zone laterally from the intrusions and 2) concentrically zoned pegmatites, contain most of the lithophile metals. A third, epigenetic replacement-type mineralization, contains much of the U resource. Other deposit types with minor or unknown resource potential include diatremes, carbonatite, and placers. This report summarizes the deposit evaluations, characterizes the mineralization, and estimates the resources. To date a total of 40.7 million tons of mineralized material is estimated as indicated or inferred. Most of the Y203 plus REO is at a grade exceeding 0.5% and half of the Nb20S exceeds 0.125%. Tonnage estimates would likely be substantially lncreased with additional exploration. Mineralogy is generally fine-grained and complex, and consists of more than a dozen principal REE-Y-Nb-U-Th-Zr phases, the sum of which may compose up to half of the rock. Approximately half of the REE-Y content comprises the heavy yttrium subgroup which is uncommon compared to deposits elsewhere. Although the Alaskan deposits are likely subeconomic at today's metal prices and consumption levels. recent technological advances suggest future demand may increase.

Jan 1, 1988

By K. M. Parida

The kinetics of dissolution of manganese dioxide in dilute sulphuric acid solution have been investigated using iron pyrites as a reductant. The dissolution rate of manganese is independent of the speed stirring but depends upon temperature, particle size, specific surface area of manganese ore, acid concentration, Fe(II) concentration and amount of pyrite. The activation energy is 43.6 KJ/mol and the linear relationship between the rate of dissolution and lido indicates that the reaction is chemically-controlled. The redox reactions of MnO2 with iron pyrites and Fe(II) are the rate-controlling reactions.

Jan 1, 1990

By Robert E. Moore

Synthetic spinel is proving to be a highly effective refractory for specific applications, but its cost limits applications. Formation of spinel from a raw material such as diaspore or bauxite could provide a suitable and less costly starting material. In the study reported here, finely ground (-325 mesh) diaspore from Missouri and bauxite from Guyana and China are combined with hardburned MgO (-325 mesh) in appropriate proportions to yield spinel and spinel with secondary phases. A classical sintering and creep study was completed, accompanied by a microstructure study to determine completeness of the reactions and morphologies of the reaction products.

Jan 1, 1991