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By Cheryl S. Lim

New technologies such as direct reduction and smelting reduction processes are increasingly being used in iron-making and steel-making in addition to conventional blast furnace technology. Critical parameters for control of these processes include the degree of metallization, degree of pre-reduction, and carbon and silica levels. On-line monitoring of these parameters is difficult because measurements often need to be made on hot ores (at or higher than -1000'C) in circumstances where representative sample streams are not readily accessible. A nuclear analyser has been developed which provides continuous, non¬intrusive, real-time measurements of iron, oxygen, carbon and silicon levels in hot ores undergoing reduction. The analyser has been tested in a plant using a direct smelting process on pre-reduced feed to the smelting vessel-, accuracies of 1% relative, 0.5 w'.96 (25% relative) and 1.0 wt.% (9% relative) were obtained for the degree of pre-reduction, carbon and silica respectively. The underlying method, capabilities and potential applications of the analyser will be discussed.

Jan 1, 2001

By Vadim J. Jabotinski

This paper describes several areas of application for electron beam processing of materials. The technology and use of electron beam systems in gas phase synthesis reactions are described. Gas phase reactions may be used to generate ultra- fine metal or ceramic powder that are very pure and crystalline. Among the examples presented are: the generation of nanometer sized metal powders and the gas phase synthesis of silicon carbide for silica and methane. The experimental system is described and future theoretical and experimental objectives are identified.

Jan 1, 1998

By Berger. P.

The accepted definition of the function of an edge protector fails to specify adequately the several tasks which it must perform to be functionally effective: detailed analysis of these tasks leads to the reasoned conclusion that they cannot satisfactorily be fulfilled by the conventional types of "edge-strips". The true cost of edge protector failure is cumulative: renewal costs are dwarfed by the increased operating expenses and production losses which result from but partial or incipient failure of the edge-strip; yet, the several supposedly improved types, for use with starter-blanks, generally were "built down to a price", prolonging the agony, as it were. Clearly, a fresh appraisal of the problem was overdue, and more especially so with the advent of "permanent" cathodes. As a result, new methods of edge .protection have been developed, including the so-called "EDGEWISE" system in which the present author as patentee *) has a vested interest-which he hereby declares. Due mention is made of recent progress in protecting the edges of aluminium "Jumbo" cathodes in zinc electrowinning operations, although the present Paper is more concerned with edge protection of starter-blanks and permanent cathodes in copper ER/EW processes, where most of the "old" problems now may justifiably be claimed to have been overcome, Mention is also made - albeit at this time necessarily only briefly, and confined to edge protection - of "rigidized" metal blanks and permanent cathodes: a most recent development**) which may prove to represent a "breakthrough": time will tell.

Jan 1, 1987

By Kimiaki Utsunomiya, Yasumasa Hattori, Yoshiaki Mori, Toyokazu Okubo

"The effect of various operating conditions on splashing behavior in a Peirce-Smith converter has been investigated with a 1/5.7 scale cold model. Dynamic similarity between the model and a commercial converter was attained by setting the modified Froude number in the model experiments in· the range for normal converter operation. It is known that for a given modified Froude number the dimensionless penetration length of gas into the liquid phase increases as the liquid density decreases. Moreover, penetration· length has a large effect on splashing behavior. Therefore, a heavy liquid, a mixture of water and lead concentrate was used as the liquid phase. It was concluded that the amount of splash dramatically decreases with a reduction in the buoyancy energy per, unit liquid mass and an increase in the horizontal distance between the tuyere tip and the edge of the mouth.IntroductionSubmerged gas injection is widely used in practice in ferrous and nonferrous pyrometallurgical operations to achieve large gas-liquid contact areas and good agitation of liquid for rapid chemical reaction. The common application in ·nonferrous industry is the Peirce-Smith converter with multi-tuyere for copper and nickel matte converting. This process has been used for over 100 years because of its effectiveness in mixing of the molten bath, as well as its merits of the engineering simplicity. However, the mechanisms which · determine the blowing performance is poorly understood, and the design and operating conditions of the Peirce-Smith converter varies widely from plant to plant, such as by diameter, length, mouth angle, tuyere position and level of molten matte. Smelters have continuously made an effort to increase converter productivity, implying maximum tuyere blowing rate. Above a certain critical blowing rate, splash of molten matte from the converter mouth becomes unacceptable because of dangerous ejection and accretion buildup around the converter mouth, which results in interference with effective hood sealing. In fact, a 1993 converter survey[!] reported that splash was a major limiting factor for blowing rate and 54% of responding plants from around the world regard it as a limiting condition[2]. In order to increase tuyere blowing rate a study of the effect of various operating conditions on splashing behavior is expected."

Jan 1, 2000

By G. Upadhya

Considerable success has been achieved recently in modeling microstructural evolution during solidification of castings bthrough the coupling of macroscopic heat transfer with microscopic solidification kinetics models. However, a complete model for simulation of solidification in complex shaped castings involves: (i) the description of fluid flow, during and after mold filling, coupled with (ii) heat transfer to the mold and surroundings by use of a macro model, followed by (iii) a description of subsequent solidification of liquid metal by use of a micro model for solidification of the alloy under consideration. This paper describes the coupling of solidification kinetics model to a 3D, transient, fully coupled fluid flow and heat transfer model. Coupling between the macremicro models is achieved by using the latent heat method. Micro models for the eutectics of gray, white and ductile iron are discussed. This coupled code has been used for predicting the thermal history and microstructural data for shaped castings. Various applications of the model, including prediction of shrinkage defects, grain density contours, and graylwhite transition region in the casting, are presented for a relatively complex casting geometry.

Jan 1, 1992

By P. Myllykoski, J. Nylander

"A commercial program package called Crownoff for the simulation of temper rolling in four high mills has been verified against measured data. The agreement between measured and calculated transversal strain distributions of the strip was found to be good. Effects of the strip crown and work roll bending force on the strain distribution were simulated. The results showed that when a single ground camber of work rolls is used for all strip widths; the strip crown should be parabolic, excluding the edge drop. An increase or decrease of the strip crown by 30 % during a coil can be compensated by a 2 to 5 t change in the work roll bending force. The ability to control the strip crown by work roll bending was insensitive to strip width. IntroductionCold rolled steel strips are usually temper rolled after recrystallization annealing, which follows cold rolling. The purpose of temper rolling is to suppress the yield point, finish the strip surface and correct possible flatness errors. The presence of a yield point might otherwise cause problems during subsequent forming processes. The in homogenous yielding in non-temper rolled steels leads to the formation of Lüders bands in the strip surface.The rolling force is influenced by the rolling speed and changes in frictional conditions in the roll bite. Therefore it is very important to plan carefully the mill settings and control algorithms during rolling. The purpose of mill control algorithms is to ensure constant reduction and the best possible strip flatness during the entire coil.Correctly predicting the rolling force is important for determining the mill presettings. Torque, forward slip and power requirements are not usually critical, if the reductions are small. However, the large elastic deformations occurring in the roll bite make the physical description of the process difficult. Physical rolling models developed for cold rolling contain assumptions that lose their validity as the reductions decrease to the level of one per cent."

Jan 1, 1994

By José D. T. Capocchi

Viscosity of liquid lead, tin, and Pb-Sn alloys has been measured by the rotational viscometer method in the temperature range from 50 K above their respective liquidus temperature to 823 K. The results are accurate to within ±1.0 %. The variation of viscosity with temperature followed the Arrhenius-type equation µ = µo.exp(Q/RT). The composition dependence of the isothermal viscosity and the activation energy for viscous flow have not shown anomalous changes at the eutectic composition of the Pb-Sn system.

Jan 1, 2000

By F. Ajersch, P: Tsantrizos, K: Shanker

"TiN films have been deposited on various substrates by a novel reactive plasma technology. In this process, a nitrogen source (NH3 or N2) and TiCl4 are reacted in the jet of a plasma torch, and are deposited onto a substrate forming TiN films at a high growth rate ( > 2µm/min). It was found that the process parameters strongly affect the microstructure, thickness, density, and growth rate of the TiN films. These parameters include source of nitrogen (NH3 or N2, N/Ti ratio, temperature of substrate, and spray distance. In general, it was found that thick and dense coatings were deposited when the N:Ti ratio was kept low, and the substrate temperature was high. Also, for the series of conditions investigated, NH3 was found to give much better results than N2•. The limitations and advantages of this technique are also discussed in this paper.IntroductionTiN is an extremely hard material and is used in many wear applications, particularly as a protective coating on cutting tools to extend their Iife(1.2). Owing to its excellent chemical stability, TiN is also frequently used as a diffusion barrier in the electronics industry for sub-micron Al/TiN/Si ohmic contact systems (3) or as a coating on high-temperature resistant alloys in gas turbine applications (4), based on its good resistance to oxidation. Other applications include decorative coatings in the jewelry industry, and specialized applications such as solar energy absorbers and transparent heat mirrors(5).TiN films can be deposited/formed using various techniques. The main techniques of deposition are CVD (Chemical Vapour Deposition) and PVD (Physical Vapour Deposition). Each of these techniques can have many variations in equipment characteristics, reactants as well as a range of process parameters (pressure and temperature). In the CVD process, TiN is generally deposited onto a heated substrate where a chemical reaction takes place. The reaction can be one of reduction(6) (e.g.: TiCI4 + 0.5N2 + 2H2 --> TiN + 4HCI), of thermal decomposition(7) (e.g. decomposition of titanium dialkylamide), or of displacement (e.g. TiCI4 + NH3 --> TiN + 3HCI + 0.5CI2)' The displacement and reduction reactions are the most common."

Jan 1, 1994

By A. Treverrow, G. A. Brooks, H. K. Worner

"The work by H.K Worner and co-workers at CRA in the 1960s, and early 1970s, established that molten metals could be refined continuously utilising counter current flow of metal and slag. Womer also demonstrated that counter current refining could produce highly refined metal products. These developments coincided with the advent of high intensity metallurgical reactors in both the ferrous and non-ferrous industries (e.g. BOS, Q-BOP and later Sirosmelt) that utilised high levels of gas injection to produce rapid stirring and very fast reaction. These new generation of high intensity metallurgical reactors allowed high tonnage rates through relatively small volume vessels.Whilst, it is well known that the counter current flow of reacting phases offers the potential of efficient mass transfer and high purity products, the application of counter current reactors to molten metal/slag systems has been criticized on the basis that they suffer from either low intensity or, alternately, from poor refining due to excessive dispersion. These criticisms relate to the balance between intensity and the refining capacity of a reactor. That is, whilst high levels of mixing transversely to the direction of flow promotes high mass transfer, longitudinal mixing (dispersion) is detrimental to refining. Of course, mixing in one direction invariably leads to mixing in other directions, thus creating a playoff between high mass transfer and excessive dispersion.This balance between intensity and refining has been the subject of recent studies overseas, and at"" the University of Wollongong, using cold modelling techniques to evaluate the effect of mixing on dispersion in a counter current refining launder. These studies have shown that for a given geometry and mixing regime, dispersion decreases with increasing flow of liquid phases. This means that whilst high mass transfer cannot be achieved in a refining launder without sacrificing the degree of refinement, there is no impediment to achieving high productivity through such a system, in fact, high through puts may favour good refining. Thus, it may be possible to match a high productivity smelting operation with a equally productive counter current refining stage."

Jan 1, 1996

By A. Mikula, S. Karlhuber

"Unique physical and mechanical properties made the Pb-Sn solders attractive for low temperature joining of electronic parts. But since lead in solder materials has become a great enviromental problem and health concern, lead will be slowly replaced by other materials in soft solders. Some of these materials which are currently under investigation are ternary tin alloys. Many different physical properties like wetting behavior, electrical and thermal conductivity and surface tension are measured on these alloys, but on the thennodynamic properties and the phase diagram of the alloys under discussion there is only little information available. We investigated the (Ag, Au, Cu)-Sn-Zn systems and determined the thermodynamic properties over the whole composition range by emf-measurements. From these measurements we also got some information on the liquidus. In the Sn-rich corner the phase diagrams are still under investigation.IntroductionSoldering is technically defined as the joining of two base materials, mostly metals or metal coated nonmetallic substrates, with a third metal. The melting temperature of the third metal or metal alloy should be well below those of the substrates. Solder alloys can be categorized in soft and hard solders. Soft solder alloys usually contain lead, tin, bismuth, indium or cadmium and hard solders gold, zinc, aluminium or silicon. The difference between soft and hard solders is the melting temperature of the soldering material. This temperature is around 350°C.An interesting brief history of solders is given by Vianco and Frear [1]. They report, that in 4000 B.C. solders were already used in Mesopotamia. From archaeoligical evidence those solders were gold-based hard solders.Tin-lead soft solders and their use are not easily found, because in course of time tin has been reduced to stannic acid, making the identification quite difficult. Well preserved soft solder artifacts were discovered in King Tut's tomb dating from 1350 B.C. In ancient time Pb-Sn solders were used primarily for the manufacture and repair of cooking utensils and metal tools. The Romans used lead-tin solders extensively in the construction of the aqueducts."

Jan 1, 1996

By Erik Olsson, Gunilla Hyllander, Stefan Schuster, Lena Sundqvist Ökvist, Maria Lundgren, Michael Hensmann, Olavi Antila

"Residual materials from the integrated steel plant itself or other sources often contain valuable compounds of e.g. C and Fe. Dust and sludge have to be agglomerated to be able to recycle to the blast furnace (BF) via top-charging. By injection of the materials, preparation methods in terms of e.g. drying and/or screening only, can be used. Alternative carbon materials (ACM) in terms of BF dust and sludge have been successfully injected up to levels of 60 kg/tHM in the LK.AB Experimental Blast Furnace (LKAB EBF®). Efficiency in recovery of valuable compounds as well as the behavior of undesired elements have been evaluated and are discussed.IntroductionTraditionally, recycling of steel in-plant fines is made via the sinter plant and blast furnace route. Steel plants operating with 100% pellet as ferrous burden and have no sinter plant. There are limited areas for land fill and costs are caused for preparation of landfills and deposit fees. Very fine paniculate dusts or sludges cause decreased productivity and increased coke rate in the sinter plant, and therefore other ways for recycling must be considered. Injecting them into the BF could be an economically and technically feasible alternative. Additionally, as the materials contain valuable compounds of e.g. C and Fe."

Jan 1, 2012

By A. Kar

A mathematical model is presented for pure titaqium deposition from titanium tetrabromide on a stainless-steel (SS 304) substrate. Five three-dimensional, transient, and nonlinear partial differential equations are used to account for the diffusion of various species inside the deposition chamber and the thermal decomposition of titanium tetrabromide, titanium dibromide, and titanium monobromide at the surface of the substrate in order to determine the thickness of the titanium film deposited on the substrate. The effects of various process parameters on the deposition and shape of titanium films are examined, and under certain conditions, the deposited titanium films are found to have volcanic profiles.

Jan 1, 1992

By G. S. Rao

Levitated drops of Fe-18%Cr-2%C were reacted with oxygen-argon mixtures to study the reactions that occur in the AOD process, where the gases are injected into the melt and form bubbles. In the laboratory an argon-oxygen pulse, followed by pure argon, was flowed past the levitated drop to simulate the transient conditions in the gas phase as the bubbles rise in the melt. Oxide layers formed on the drops immediately when they came into contact with gas pulses containing 75% or more oxygen. Once the oxygen flow had ceased, the oxides reacted with the carbon in the drops to form CO gas and eventually disappeared. The de-carburization reaction occurred without oxide formation when the gas contained 50% oxygen or less. Melts that were sampled after EAF tapping, ready to be charged into the AOD, showed a higher tendency to oxide formation and consequent carbon boil than pure ternary Fe-18%Cr-2%C alloys made in the laboratory. The actual steel samples contained significant impurities, such as 0.25% Si and 0.56% Mn. A similar effect of oxide-forming impurities had been observed previously with binary Fe-C alloys. Movies were taken of the oxide formation and decomposition, and the results will be presented, along with data on the experimental conditions, including temperature and oxide compositions. The results are important because they give an insight into the reaction mechanisms in the AOD, which must be understood in order to improve and model the process.

Jan 1, 2006

By Richard D. Hangi

Process mineralogy techniques are uniquely applicable to industrial problems related to the extractive metallurgy of nickel, cobalt, and associated metals. Reflected 1ight microscopy, together with selected determinations by scanning electron microscopy-energy dispersive spectrographic analysis and electron probe microanalysis, provides the means to identify the ore minerals cobalt and nickel ores, determine the abundance of each ore mineral, assess the extent of intergrowth between the cobalt and nickel minerals and other ore and gangue minerals in the ores and concentrates, and predict the potential success of cobalt and nickel extraction by grinding, flotation, pyrometallurgical, and hydrometallurgical treatments. In addition, the extent of locking of the cobalt and nickel minerals with each other and with the gangue minerals can be directly observed by reflected light microscopy. Where ores have been treated by hydrometallurgical procedures, reflected light microscopy can serve to determine the causes of excessive leach consumption. Finally, the partitioning of cobalt and nickel between high-temperature synthetic phases produced by pyrometallurgical treatment can be precisely determined by process mineralogy techniques. Case histories from cobalt and nickel deposits illustrate the value of applied mineralogical techniques in the study of cobalt and nickel ores, beneficiation, hydrometallurgial, and pyrometallurgical products.

Jan 1, 1993

By B. C. Jena

Activities of carbon, cobalt and nickel were evaluated in the ternary systems iron-carbon-cobalt and iron-carbon-nickel for the temperature range 1300-1600°C for cobalt and 1300-1700°C for nickel. The carbon activities were determined from the knowledge of activities (1) in the binary system iron-carbon, (2) in the dilute ternary systems and (3) from the knowledge of carbon saturation data. The activities were mathematically expressed with the Taylor series expansion of Wagner's interaction parameter formalism modified to suit concentrated solutions. The cobalt and nickel activities were determined from the knowledge of carbon activities by applying the Gibbs-Schuhmann integration and from cobalt and nickel activities in the binary systems iron-cobalt and iron-nickel. Partial molar enthalpies of mixing were determined based on the temperature behaviour of the activity coefficients.

Jan 1, 1992

By Satu Jyrkönen

A single-particle laminar-flow technique was used to study reactions of sulfidic nickel particles. The studied materials were three natural nickel concentrates and four synthesised nickel mattes. The variables of the experiments were the gas preheating temperature (500 - 1300°C), the composition of the reaction gas (N2 + 0 - 75 vol-% 02) and the ,particle size of the feed. Chemical analysis of the particles was used to determine the oxidation degree of the materials, and optical and scanning electron microscopy were used to detect alteration in their morphology, internal composition and structure. General reactivity of the materials was monitored by the extent of sulfur removal. The reaction mechanism of the studied materials was found to depend primarily on the materials composition as well as oxygen content of the reaction gas.

Jan 1, 1998

By H. Masuda

The lijima Zinc Refinery started operation in 1972, and has today an annual capacity of 200, 000+-Zn. The hematite process was employed for the first time and the ideal of waste-free refinery has been pursued for 30 years. In recent years, however, only half of the hematite produced would be sold to the cement industry and hence a reduction of arsenic level has been necessary in order to sell the entire amount produced, The arsenic cementation process with zinc powder, developed through a long time laboratory research was found among some options as the best for the hematite process. The construction work started in 2000 and the facility was put into operation in 200 I. As a result in the same year all hematite were sold to the cement industry. The outline of this project, present operations and technical issue are reported in this paper.

Jan 1, 2003

By Richard D. Hagni

Process mineralogy has not been given adequate attention in years past, because geologists have not been sufficiently interested in applying mineralogical techniques to industrial processes, and most process engineers are not adequately trained to use them. Although some individuals and institutions have made efforts to improve the situation, it is only in the last few years that the significance of applying the methods of mineralogy to a wide variety of industrial processes has been fully appreciated. Presently, the formation and organization of several groups devoted to applied mineralogy have created a more amenable climate for the development of process mineralogy. As a result, the presentation, discussion, and publication of the results and case histories of process mineralogy have become fairly common. Short courses affording hands-on experience with applied techniques are now available to the many geologists and process engineers engaged in industrial mineralogical processes. The future role of the process mineralogist is viewed as an expanded one, which will increase in value.

Jan 1, 1982

By Li. Jiarong, Zuojian Liang, Qingyan Xu, Baicheng Liu, Shizhong Liu, Hailong Yuan

Single crystal solidification of turbine blades is a key technology for the production of reliable and high efficiency gas turbines. The solidification process of single crystal investment castings causes a number of problems that have to be solved such as the increase of casting defects and complexity of production process. Computer modeling and simulation is helpful to predict the defects and improve the process design. In the paper, a mathematical model for three dimensional simulation of solidification and single crystal growth of investment castings was developed based on CA, mechanism of crystal growth and basic transfer equations such as heat, mass transfer equations. Many factors including constitutional undercooling, curvature undercooling and anisotropy, which had vital influences on microstructure evolution, were considered in the model. Temperature, crystal growth interface and structure defects of investment castings of single crystal superalloy were investigated at withdrawal rates of 4.5mm/min and 7mm/min. Simulated results showed that microstructure evolution and structure defects were predicted reasonably and calculated results were coincident with experimental ones. The study indicated that three dimensional solidification simulation technique is a powerful tool for understanding the fundamental of solidification and the formation of structure defects in single crystal investment castings and finally for optimizing process design.

Jan 1, 2004

By B. C. Blakey

Unlike most hydrometallurgical slurries, those containing significant concentrations of goethite are typically highly viscous and shear-thinning, even at solid volume fractions below 5%. The viscosity may also depend upon time. These characteristics must be taken into consideration in slurry transport and heating. The technical literature is replete with apparent contradictions regarding the viscous behavior of these slurries, which may be due, in part, to variations in viscosity-measuring techniques. We present techniques that yield consistent results suitable for use in process design. A striking degree of time-dependent behavior is demonstrated for a laterite slurry. Reliable methods to design and analyze tubular transport and heating systems for time-independent slurries are summarized. Rules of thumb are then offered to account for the effects of time-dependency.

Jan 1, 2000