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By Y. Ono

In lightweight metal processing such as aluminum (AI) and magnesium (Mg), metal cleanliness is a crucial process parameter for refining, part manufacturing and recycling in order to obtain high quality parts and products. In this paper, techniques for cleanliness evaluation of molten AI and Mg using ultrasonic probes with clad steel buffer rods having high signal-to-noise ratio (SNR) are presented. Due to the high SNR of the ultrasonic probes used, backscattered ultrasonic signals from inclusions, which may be oxide films and/or particles, in molten Mg and those from silicon carbide particles, having an average size of 50f.Ull, added in molten AI are successfully detected with reflection configurations of pulse-echo and/or pitch-catch modes at an ultrasonic frequency of 10 MHz. In addition, relative cleanliness evaluation of molten Al and Mg is demonstrated. In order to establish the procedure and to investigate the optimum system configurations for cleanliness evaluation of molten metals, particle flow simulation system using water and polyvinyl chloride (PVC) particles has been constructed. Counting the number and measuring the size distribution of the PVC particles, having an average diameter of 128um, suspended in water with the PVC volume concentrations of 5ppm and 10ppm are performed with ultrasonic pitch-catch mode. The counted numbers of particles by the presented method and system have good agreement with the calculated results with a count error of less than 10% or two counts. Based on the results obtained with water simulation experiments, the prototype system for cleanliness evaluation of molten Mg by counting and sizing inclusions has been developed. Keywords: Ultrasound, Clad buffer rod, Molten metal, Aluminum, Magnesium, Inclusion detection, Cleanliness measurement, Counting, Sizing

Jan 1, 2003

By Peter Fischer

A demonstration plant for QSL technology with a continuous through-put of up to 10 t/h concentrate has been in operation at the Berzelius smelter, Duisburg, Germany since early 1981. In the QSL-process, both oxidation and reduction steps are performed in a single horizontal long cylindrical reactor. In the present demo-reacior, 2.5 M diameter by 22 M long, these steps are separated by a low partition wall with an underflow opening, to prevent backmixing of slag. -Tests on a variety of concentrates, including high-lead Missouri-type material and lower grades, have shown recoveries and consumables indicating very attractive economics. Investment cost estimates further enhance the economic attractiveness. Environmental protection afforded by the QSL system is a major advantage. The process has proven its reliability and versatility and is now ready for commercialization. Continued test work, including smelting secondary lead materials, is planned.

Jan 1, 1983

By Miroslav Raudensky, Kallol Bera, Jaroslav Horsky, Jee G. Chang, Ampere A. Tseng

"A combined experimental and finite element approach to study the local heat transfer coefficient is presented in this paper. The heat transfer coefficients at different cooling regimes in a roll are quantified by an inverse heat conduction technique; the heat transfer phenomena involved are then discussed. A discussion of the application of the heat transfer information found in the present study for better design of a roll cooling system is also included. Finally, an identification of areas where further work is needed is presented.IntroductionIn metal rolling processes, the roll is used as a tool to deform the workpiece at very high speeds. As shown in Fig. 1, the heat transfer phenomena involved in the process are complicated by the interaction between the roll and the strip, mainly including 1) the heat transferred from the workpiece to rolls in the contact regions, 2) the heat created in the interface due to the deformation of the workpiece and the friction between the workpiece and roll, and 3) the heat removed by watercooling as well as the ambient air. All of these transport phenomena occur at extremely high pressure, high speed, and high heat flux; these make the control of the roll temperatures an extremely challenging problem.In hot rolling, proper cooling of rolls can lead not only to improve the roll shape quality by controlling the thermal crown of the roll, but also to extend the roll life by minimizing the thermally induced stresses [1,2]. Also, knowledge of roll temperatures can contribute to insights about the roll/workpiece interfacellubricant behavior, and lead to the desired surface condition of the workpiece. Therefore, adequate roll cooling or control of roll temperatures is of critical concern to mill designers and process engineers. In order to have proper operation of the process, a good understanding of the influence of cooling practices on the roll is essential [3]."

Jan 1, 1994

By C. A. Young, J. D. Miller

Adsorption isotherms previously determined by in-situ Fourier transform infrared/internal reflection spectroscopy (FT-IR/IRS) for oleate adsorption at calcite and fluorite surfaces near pH 9 and at various temperatures are compared. Results indicate that, at both mineral surfaces, chemisorption occurs at equilibrium concentrations below approximately l x l0-5 M oleate while calcium dioleate surface precipitation occurs at higher equilibrium oleate concentrations. The extent of chemisorption at the calcite surface is 3 to 5 times less than that at the fluorite surface while the extent of calcium dioleate surface precipitation on calcite is nearly a magnitude larger than that on fluorite. However, for both minerals, surface precipitation decreases with increasing chemisorption. Contact angle measurements and flotation recoveries show the hydrophobicity of fluorite to be greater than that of calcite at each of the temperatures and oleate concentrations studied. Significant differences are noted only in the chemisorption region. Unlike calcite, the hydrophobicity of fluorite was sensitive to the presence of oxygen in the system. Multichannel Laser Raman Spectroscopy (MLRS) showed this behavior was caused by the double-bond reactivity of adjacent chemisorbed oleate molecules and subsequent formation of an epoxide/polyether complex at the fluorite surface. Such a reaction product could not be detected at the calcite surface. These differences in adsorption density, hydrophobicity, and polymerization behavior are discussed in terms of the intrinsic surface properties of the minerals.

Jan 1, 1999

By G. A. Irons, D. Guo, D. Angheiina

To produce low-carbon (<30 ppm) steel in the tank degassing process, a ladle of steel with an oxidizing slag is placed in a vacuum tank equipped with bottom bubbling. The kinetics of this process are slow compared to the more prevalent RH degassing process, providing the impetus for the present work. There are several aspects to this work: water models of the fluid flow in the ladle; simulation of the decarburization (CO evolution) with C02 desorption in water; pilot-plant (60 kg) studies of the decarburization kinetics; mathematical modelling of the fluid flow in the ladle; mathematical models for each of the kinetic sites (plume, top slag and auto-nucleation); and full-scale trials. The results show that during the refining cycle the contribution from each reaction site changes, suggesting avenues for reducing cycling time and final carbon contents.

Jan 1, 2000

By R. Reed von Gal

The majority of zinc strip produced in the world today is cast on the Hazelett twiri-belt continuous casting machine. Ten of these machines are currently operating worldwide, and one machine is under construction for the People&apos;s Republic of China. The caster, which was first patented in 1947, was originally developed for aluminum and copper alloy casting. In the early 1960s, the design was expanded into zinc casting and within ten years the industry had essentially converted from casting and rolling ingots to twin-belt continuous casting with in-line rolling. The casting process employs two parallel, moving. water-cooled belts as the major mold surfaces. Together with two strings of side dam blocks, the design offers a four-sided moving mold which produces a continuous strip or bar. This paper will cover a bit of, the history, as well as the current technology surrounding this high production process for zinc strip production.

Jan 1, 1990

By Autumn Fjeld

The filling and solidification of an industrial scale composite casting has been simulated to investigate the re-melting of the outer shell material during casting. Production of a composite requires a two-step casting process which includes centrifugal casting of a hard outer shell material and subsequent conventional ingot casting of a tough core material into the shell-mold assembly. During casting of the core, a thin layer of the shell material re-melts and mixes with the core material producing a bonding layer of intermediate composition. The present numerical model employs the volume of fluid method and an enthalpy-porosity technique to couple the filling of the core material and re-melting of the shell material. The interface between the two materials is tracked and can be used as a guide to examine the extent of melting and, to some degree, mixing of the two fluids and species diffusion.

Jan 1, 2008

By Elli Miettinen, Markku Lahtinen, Ilkka Kojo

"The recent trends of decreasing energy consumption and environmental emissions and utilization of economies of scale are strong drivers favoring continuous copper converting processes. Flash Converting benefits from low off-gas volumes and low investment and operational costs for off-gas treatment. Separate matte and blister furnaces allow the adaptation to concentrate quality changes and flexibility in layout and maintenance.The stationary blister copper bath in Flash Converting furnace is less aggressive to the furnace linings than agitated processes, resulting in low refractory consumption, long campaign life and high on-line availability.Copper Flash Converting has been successfully applied in Kennecott with a campaign life now exceeding five years. A second FCF was started at Xiangguang Copper in China in 2007. The process itself is proven, as its features are similar to those in FSF, Direct-to-Blister and Direct Outotec Nickel Flash Smelting (DON), with one significant difference: it is the easiest of all to operate.The paper presents differences between continuous Flash Converting and conventional converting based on recent experiences and studies."

Jan 1, 2009

By Ray Y. Lin, Randall A. Blue

"Joining of silicon carbide with infrared using a mixture of Si-30wt.%C as the brazing material has been investigated. Joining was performed at a temperature of 1500 °C in a flowing argon atmosphere for processing times ranging from 5 to 60 seconds. The joining filler materials include thin film silicon obtained by thinning down silicon wafers to about 70 /!m and graphite powder of a 15 /!m average particle size. Joint strengths were determined with a specially designed shear-in-compression jig for testing shear strengths of brittle materials. Cross section examinations of the joined specimens with optical microscopy, scanning electron microscopy and transmission electron microscopy have shown that all joints are essentially void free with excellent wetting between the base SiC and the brazing material. Silicon carbide in the B form has been identified as the reaction product in the joining zone with a transmission electron microscope (TEM) and selected area diffiaction (SAD) analysis. At 1500 °C with a joining time of 60 seconds, the joint has consisted of primarily SiC. With such a high SiC content in the joint, the joint strength is comparable to those by other joining techniques, such as diffusion bonding, as reported in the literature. A kinetic model for the formation of SiC from liquid silicon and carbon is proposed to explain the observed joint microstructural evolution.IntroductionSilicon carbide is of great interest for high temperature structural applications because of its excellent high temperature strength, wear resistance and anticorrosive characteristics [1]. Even though the interest in SiC is high, the use of the material has been limited by the high cost and difficulties involved in forming components of complicated shapes [2]. It is these limitations that necessitate the development of effective joining techniques that are cost effective and able to provide strong joints."

Jan 1, 1996

By J. R. Kiji

The Cerro Matoso S.A. mine and smelter, in the Cordoba lowlands of northwestern Colombia, consist of a dedicated laterite nickel mine, ore blending, drying and an RKEF process to produce high-quality ferronickel. At a project investment of $400M, first production of ferronickel was in September 1982, and in its inaugural year CMSA produced 6,150 tons of contained Ni from a mined ore grade of 3.2% Ni. Initial operational difficulties resulted in a number of furnace run-outs, which impacted ramp up to design ore throughput of 128 dry t/h Since then CMSA has steadily incorporated process improvements and initiatives to take the single line operation to an ore throughput of 175 dry t/h. A second 175 dry t/h line was added in 2001 (investment of US$ 300M) to consolidate CMSA as one of the world&apos;s lowest cost Ni producers with an installed annual production capacity of 50-55,000 tons Ni. The most recent addition is commissioning of Phase I of an ore-upgrading project to counteract the effect of declining ore grades. Keywords: Laterite, ferronickel, pyrometallurgy, smelter.

Jan 1, 2004

By P. Schloth, H. van Swygenhoven, N. Chobaut, J-M. Drezet

"In the current trend toward thicker aluminium plates, a major concern is the stress build-up during quenching which causes distortions during machining. Indeed, cooling rates are not high enough, especially at the core of such thick plates, to prevent any precipitation and quench induced precipitates lower the hardening potential. Multi-scale modelling is required when predicting macro-scale stresses after quenching for thick heat treatable aluminium components. The reason is the instantaneous strong coupling between phase precipitation at the nano-scale and material hardening due to precipitation or softening owing to solute depletion at the microscale. For thick parts, quenching intensities decrease when going from the skin to the core of the component, thus introducing a gradient of nanostructure and consequently a gradient of mechanical properties. In addition, large thermally induced deformations lead to high macroscale residual stresses although part of them is relaxed by plastic deformation. These stresses have been measured in water quenched thick plates of 7040 and 7449 aluminium alloys using neutron diffraction and layer removal techniques and the results when compared with a thermomechanical finite element model of quenching highlight the influence of precipitation.IntroductionIn the processing route of heat-treatable aluminium alloys (AA), a critical step is quenching from the solutionizing temperature. High cooling rates are desired, as they avoid formation of coarse precipitates, which reduce mechanical properties. Fast quenching, however, cannot be achieved in the centre of thick components, where the quenching rate can be more than one order of magnitude lower than at the surface. The existence of a thermal gradient between core and surface leads to a differential thermal deformation which is accommodated by elastic and plastic deformation to comply with the compatibility of deformation. Whenever the material yields, especially at high temperature when the yield strength is low, residual stress remains after quenching due to the irreversibility of plastic deformation. After quenching, the plates are in a state of residual stress that causes unacceptable distortions during machining and may reduce service life drastically. Since stress relaxation is negligible during ageing treatments [1 ], agehardened aluminium parts are usually stress relieved prior to ageing. This is typically achieved by applying plastic deformation: stretching from 1.5 to 3 % in the rolling direction (L) can reduce the internal stresses by a factor of approximately 10 [2, 3]. However, complex geometries or thicker components like thick sheets require other approaches. Reducing the quenching rate by using boiling water for instance leads to lower residual stresses [1, 4]."

Jan 1, 2013

By Pengfu Tan

A thermodynamic model and computer program, CuModel, has been developed to model the distribution behaviors of Cu, Fe, S, O, Ni, Co, Sn, Pb, Zn, As, Sb, Bi, Au and Ag, copper loss in the slag, and heat balance in copper smelting process, matte converting process and copper con-tinuous smelting process. It can be predicted for any set of controllable process parameters such as feed composition, smelting temperature, degree of oxygen enrichment and volume of oxy-gen-enriched air. This model accounts for physical entrainment between matte and slag phases. It can be used in Isasmelt process, copper flash smelting process, Mitsubishi process, P-S con-verting process and Noranda process. The predictions by the present computer model are com-pared with the known commercial data from Guixi Smelter in China, PASAR Corporation in Philippines, Horne Smelter in Canada, MIM Limited in Australia and Naoshima Smelter in Ja-pan. The agreements between the computer predictions and the commercial data are excellent. In this paper, the applications of CuModel in the copper metallurgical industries have been pre-sented. CuModel has been used by Daye Smelter and Guixi Smelter in China, and by PASAR in Philippines as well.

Jan 1, 2004

By R. J. McClincy

The potential techniques for the direct smelting of copper sulfide concentrates to blister copper were evaluated from the standpoint of commercial application. Many existing smelters are adaptable to direct smelting practice but only with improved control of metallurgical performance. Modified and innovative procedures for slag cleaning and metal refining, prerequisites to direct smelting, are presented and discussed. The ability to smelt directly to blister copper using existing equipment and eliminating the need to convert matte offers ,significant advantages to traditional smelting practice from the viewpoint of cost, &apos;S02 control, and process simplicity.

Jan 1, 1983

By Bien Ferrer

In most smelting operations, there is a strong incentive to improve safety, reduce downtime and extend the campaigns of furnaces and related equipment. An asset management strategy that is based on information, rather than simple throughput metrics and intuition, can be developed to improve uptime and unlock value currently unrealized at existing smelters. Advances in digital technology, including data analysis, modelling and monitoring for hot pyro-metallurgical vessels, make it possible to assess the current condition of an asset, as well as to make more informed projections about its future condition, using on-line and historical data. This would allow practices around asset management to be more proactive and less reactive, with the end-result of optimized uptime. ‘Digital Asset Management’ describes a concept in which digital technology is used to support an asset management strategy and accelerate decision-making by providing information on what, why and how an asset should be designed, operated or maintained. With the overall goals of effective resource utilization, optimized operations, capital efficiency and social acceptance, Smelter 4.0 is a program of holistic improvement and is underpinned by the effective use of data to drive decisions. This paper focuses on Asset Reliability, which is one of the improvement pillars of Smelter 4.0, and introduces a methodology that is aimed at closing the gap between recorded data and evidence-based decision-making through Digital Asset Management.

By E. Ozberk

The copper and nickel smelting industries are important contributors to the technical and economic well-being of Canada while some of the smelters are among the largest sources of sulphur dioxide emissions in Canada. A review of the operations in six smelters - Falconbridge Limited, Falconbridge, Ontario; Hudson Bay Mining and Smelting Co. Limited, Flin Flon, Manitoba; Inco Limited, Copper Cliff, Ontario and Thompson, Manitoba; Noranda Mines Limited, Horne Division, Noranda, Quebec and Gaspe Mines Division, Murdochville, Quebec - have shown that about 80% of the total sulphur input to these smelters was emitted to the atmosphere in 1980. A simultaneous review of the existing and emerging technologies which can directly or indirectly reduce the sulphur dioxide emissions indicated that it is possible to reduce the emissions to below 20% of the sulphur input to these smelters. This can be achieved by varying degrees of modifications to the smelting operations and installing sulphur fixation facilities at significant costs which may increase the metal production costs. This would consequently make the competitiveness of the Canadian copper and nickel producers more difficult in the already tough world metals market.

Jan 1, 1983

By A. F. Saavedra, N. E. Richards, C. J. McMinn

"The aluminum industry in general and Reynolds Metals Company in particular have continued to support development work for improvement of the Hall cell design and for alternative processes for the reduction of alumina. The evolution of the Hall cell design will continue into the next century as a result of further development of mathematical models, sophisticated control systems and new materials for cell components. This paper discusses the areas in which the new generation cell advances will differ from the present day design. Additionally, Reynolds Metal s has supported work for the development of a carbo thermic process to reduce alumina. Theoretical work has indicated that this process could possibly have economic advantage over the Hall process. Several complicated furnace configurations have been proposed to provide the conditions for successfully reducing alumina. The results of small pilot scale operation and most promising furnace design are discussed. For comparison, projected capital investment costs and operation costs are discussed. IntroductionThe evolution of the Hall-Heroult process will continue into the next century. This evolution will be influenced by economics, more .restrictive environment and worker protection requirements, and technological development. These factors will also cause changes in the competitive position of alternate processes for aluminum production.Several aluminum producers have made major investments in alternate processes for aluminum production in the past three decades and there is continued support in some companies for improvements in the Hall-Heroult process and for alternate processes. The more visible development work in reduction technology, not aimed at significant process changes, is in the areas of higher amperage cells with bus bar designs to reduce harmful magnetic effects, more advanced and automated feed, voltage and electrolyte composition control, improved energy efficiency and sol id waste disposal . Efforts to bring significant change to the reduction process are being made in development of materials that can function as inert anodes and cathodes. These materials could lead to the development of reduction cells with multiple bipolar electrodes operating on oxide feed and fluoride electrolytes. Development work on new processes was reduced in the last decade by several companies because of economic and technological realities. Reynolds Metals supported work on a carbothermic process to reduce alumina and produce commercial pure aluminum. This work progressed through small pilot plant operation, and resulted in development of furnace designs and operation regimes. This paper reviews how this and other technologies could influence the reduction of alumina beyond the year 2000."

Jan 1, 1988

By B. Garcia-Egocheaga, J. Rutten, N. Goicoechea, U. Meurer, Mager K., W. Saage, Simonettim F.

Because of the increasing use of zinc as an active and passive anticorrosion agent for steel, leading to constantly growing return rates of galvanized steel components, especially through the automotive industry, major Electric Arc Furnace (EAF) flue dust amounts with higher zinc contents will accumulate in future. Landfilling of steel plant flue dusts is no longer allowable for ecological reasons. These dusts are classified as hazardous by law. Waelz technology is safe and reliable. The range .of treatable feed materials has been extended by process modifications and state-of-the-art offgas technology. Waelz oxide, the product, is delivered to metal smelters for zinc production and the byproduct, Waelz slag, can be used in road construction. Despite the fact that Waelz technology is among the best available techniques (BAT), it is continuously being optimized further with respect to energy input, product and offgas quality in order to comply with the ever more stringent environmental regulations. However, if these flue-dusts are treated, the loops between the steel and the zinc industry can be closed by reusing recovered zinc which in tum leads to savings in natural resources and a more reasonable use of landfills.

Jan 1, 2000

By Dale Zacherl, Andreas Buhr, Rainer Kockegey-Lorenz

"The microporous calcium hexaluminate insulating material SLA-92 has been introduced as an alternative to refractory ceramic fiber and other insulating refractory materials. Key properties associated with this product include: high chemical purity, long term high temperature stability up to 1500 °C, low thermal conductivity up to 1500 °C, and high thermal shock resistance. The properties of the new material and various applications in the steel and ceramic industries have been reported in previous papers. The current paper summarizes the industrial application experiences with innovative refractories based on SLA- 92 and discusses potential new applications in various manufacturing as well as energyrelated industries.IntroductionSLA-92 was introduced to the refractories industry in 1998 by van Garsel, et al. [1] as a new insulating raw material for high temperature applications, followed by investigations [2] of long term temperature stability for this new lightweight aggregate up to 1500°C.SLA-92 was developed as an innovative alternative to commonly used refractory ceramic fibers. It has unique properties regarding chemical purity and mineral composition and is a microporous, silica-free calcium hexaluminate (CA6 – mineral name: hibonite)."

Jan 1, 2010

By E. N. Mounsey

Ausmelt Technology was selected by Bindura Nickel Corporation (BNC) as the basis for a new copper circuit to process nickel plant copper leach residue to blister, anode and finally cathode copper and recover PGM values at the Bindura Smelter Refinery (BSR). The process selected, based on Ausmelt Technology to smelt and convert the residue to matte and blister copper and produce a discard slag, is novel incorporating smelting, converting and slag reduction process steps in a single Ausmelt vessel. The process demands a high quality blister copper product with low levels of arsenic and nickel. This paper reviews the project and the initial operational results to the end of 1997 of the Ausmelt Top Submerged Lancing (TSL) smelter and discusses the implications for the wider TSL converter market.

Jan 1, 1998

By Saeid Pournaderi, Ahmet Geveci, Ender Keskinkilic, Yavuz A. Topkaya

There are mainly three commercial nickel laterites in Turkey: Gordes, Caldag and Sivrihisar. The first two appear in Western Anatolia. The third one, Sivrihisar (Yunusemre) laterites have been found in the first decade of the millennium, in the Central Anatolia region of Turkey. Since then, mining facilities have been continued in Yunusemre. Calcination, prereduction and smelting of Sivrihisar laterites have been extensively studied and published. In the current work, some results of the studies related to characterization of Sivrihisar laterites will be presented.

Jan 1, 2016