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By R. P. Tavares, M. Isac, R. I. L. Guthrie

"The configuration of the metal delivery system used in twin-roll casting can play a significant role in determining both internal and surface quality of the strips produced by this process.In the present work, a mathematical model for coupled turbulent fluid flow, heat transfer and solidification was developed and used in the study of metal delivery systems for twin-roll casting of low-carbon steels. This study was applied to a pilot twin-roll caster being investigated in Canada, with a roll radius of 0.3 m, producing strips of thicknesses from 4 to 7 mm, at roll speeds ranging between 4 and 12 m/min. Various configurations of metal delivery systems were simulated and their effects on the advance of the interdendritic solidification front and levels of turbulence and temperature within the caster investigated. According to the predictions of the model, an extended nozzle with inlet flow towards the surface of the rolls seems to be the best alternative for feeding liquid steel into twin-roll casters.A full scale water model of a pilot twin-roll caster was also built and used to qualitatively validate the predictions of the mathematical model.Various techniques for fluid flowvisualization were applied. In general, the predictions of the mathematical model were in reasonable agreement with the experiments with the water model."

Jan 1, 1999

By Jun Lu, Min Chen, Wei-jian Su, Jian-zhong Luo, Yu-tao Lei

"In the case of treating phosphatizing wastewater containing zinc, zinc had an impact on the solution chemistry, especially on pH. Fe2(SO4)3 and CaCl2 were used as precipitators to remove phosphate from zincic phosphatizing wastewater and the optimum pH was investigated. Zinc ion had a significant effect on the optimum pH. The optimum pH ranges were 12.10(inlet concentration of 15.67mg/L, outlet concentration of 9.53mg/L), 3.04-5.50(inlet concentration of 11.97mg/L, outlet concentration of 0.44-0.26mg/L), and more than 10.72(inlet concentration of 12.24mg/L, outlet concentration of less than 0.47mg/L) under the conditions without precipitator, with Fe2(SO4)3 and with CaCl2 respectively.Introduction Phosphate coating is commonly used for protective coating of machine elements. Including oil removal by caustic washing, rust removal by acid washing, phosphatization and inactivation, the phosphatization process produces wastewater containing inorganic salt of high concentration, especially the phosphate, beyond the environmental standards and polluting environment seriously. What’s more, the wastewater from zincic phosphatizing technology also contains another pollutant, zinc. At present, Chemical Precipitation (CP) and Biological Nutrient Removal (BNR) are two of most common technologies of phosphate removal. BNR, such as A/O, A2/O and UCT technology, is suited for wastewater containing organ phosphorus of low concentration and CP for wastewater with phosphate of high concentration [1]. Researches on CP treating wastewater containing phosphate of high concentration, mainly focus on adding quantity of precipitators[2-5] and coagulants[2-4] and the choice of technologies[3-9]."

Jan 1, 2008

By Toshiro Kuji, Masakazu Fujita, Tetsuji Saito

"The magnetic properties of the magnetic materials were deeply dependent on the microstructures. In this study, the novel technique to produce the desired microstructures in a controlled manner was proposed. The technique consisted of the production of the amorphous alloys and the control of the crystallization process. The technique was applied to improve the magnetic properties of Nd-Fe-B permanent magnets. The microstructural control of the magnets exhibited the excellently high energy-products of higher than 430 kJm-1. The relationship between the magnetic properties and the microstructures of the Nd-Fe-B permanent magnets was discussed.IntroductionThe intrinsic properties of the materials are basically determined by the properties of the constituent elements or the compounds. However, it is often noticed the difference between the observed properties and the theoretical values expected from the intrinsic properties of the materials. This indicates that the observed properties of the materials are determined not only by the properties of the constituent elements. In other words, the observed properties of the materials are also strongly dependent on the morphology of materials. This means that the microstructural control may creates a great improvement of the properties of materials.In Nd-Fe-B permanent magnets, the superiority arises from the uniaxial intermetallic Nd2Fe14B compound which has a large saturation magnetization and a high anisotropy field [1,2]. The magnetic properties of the Nd-Fe-B permanent magnets are dependent on the microstructure, that is, the size, shape and degree of the crystallographic alignment of the Nd2Fe14B phase. Currently, the Nd-Fe-B permanent magnets have been produced by either sintering or melt-spinning [3,4]. In the sintered magnets, alignment of the Nd2Fe14B phase is achieved by the prior green compaction of the crushed ingot powders in an applied magnetic field [3]. In the melt-spinning approach, alignment of the Nd2Fe14B phase is achieved by hot deformation [5]. Amorphous melt-spun ribbons are comminuted and then are consolidated into bulk form by hot pressing before hot deformation. As-hot-pressed magnets have randomly oriented Nd2Fe1~ grains [6]. Subsequent die upsetting of as-hot-pressed magnets gives rise to the crystallographic alignment of the Nd2Fe14B phase."

Jan 1, 1998

By Arsenio Enriquez, Adrian Deneys

"Rio Tinto through its subsidiary Kennecott Utah Copper Corporation (KUC) and Praxair have implemented the CoJet® gas injection system for copper anode refining. The system provides the capability to melt on average 60 to 70 tons of scrap copper per heat (with acceptable NOx emissions). The system has demonstrated the potential for tuyere-less sulfur and oxygen removal using coherent jet technology.This paper describes the process concept, system development, laboratory testing, implementation, current operation and ongoing developments."

Jan 1, 2009

By Paul E. Queneau

The QS (Queneau-Schuhmann) copper converter is a gently sloped, stepped, horizontal kiln-type tilting reactor in which desired bath oxygen activity, compositional and temperature gradients are created by countercurrent flow of matte and slag phases through a series of controlled bubble plume, mixer-settler configurations. Flow of gas and slag is normally concurrent. Copper sulfide concentrates are top-fed, employing oxygen flash burners. Oxygen and oxygen-carbonaceous fuel mixtures are bottom-blown into the smelting bath through judiciously located, independently regulated submerged injectors. Composition and mass flow rates of injector inputs are controlled to produce bubble plumes of desired character, without jetting through and out of the bath. The mixer-settler pattern can be reinforced if desired by employment of suspended shallow baffles. State-of-the-art instrumentation provides timely information required to govern key process variables. The outstanding capabilities of the QS converter for coppermaking have now been indicated by the current success of industrial QSL (Queneau-Schuhmann-Lurgi) leadmaking reactors. Modified converter designs are employed for leadmaking, nickelmaking and steelmaking.

Jan 1, 1993

By K. Yamada, T. Takaoka, A. Ozeki, M. Yamaga, Y. Kawai, S. Nishioka, Y. Kikuchi

"Recently, smelting reduction of chromium ore in BOF has been actively investigated as a key unit process for an innovative future stainless steelmaking. The prominent feature of this new process route is energy and process saving, and production cost saving. The development is already in the midst of application to the commercial production, however there still remain the following key technologies to be established for the full use of the process. One is a speed up of the reduction of chromium ore to match with sequential continuous casting, and the other is efficient combustion of carbonaceous materials in BOF to reduce their consumption, and hence to assure the steel quality. High degree of post combustion technology and new charging technology, i.e., ore-coal-flux-oxygen mixed injection, could be effective for those two subjects. In 2000 or beyond, the new process would have become quite popular owing to the establishment of those key technologies.Introduction Since stainless steel was invented, its production has continued to expand because of its attractive combinations of functions of excellent corrosion resistance, good formability, a pleasing appearance, and a wide range of strength levels. New types of stainless steels as well as new applications are continually being developed.Compared to the production of ordinary steels (1), stainless steel production (2,3) shows steady growth worldwide, while the former production remains on the same level, as Figure 1 shows. It can be estimated that future production would show further growth since materials consumer demands are more fashionable, or more functional, which could be satisfied by stainless steels.Thus market needs would be met, if it could be produced with reasonable production cost. The emergence of an innovative production technology is then potentially requested as VOD and AOD processes have emerged, which has saved substantial production cost. This paper describes a possibility of a future stainless steelmaking process, which uses the in-bath smelting reduction of chromium ore in BOF, and which would save production as well as energy cost."

Jan 1, 1988

By Pinai Mungsantisuk

Keywords: Pd-Ni alloys, Pd-Fe alloys, Pd-Co alloys, Magnetostriction, Magnetic Properties The presence of congruent melting minima, the occurrence of ferromagnetic transition over a large composition range, and FCC type crystal structure make Pd-Ni, Pd-Co, and Pd-Fe based systems attractive candidates in our search for materials with no rare-earths, large low-field magnetostriction, and good mechanical properties. The presence of paramagnetic-ferromagnetic transition over a broad range of composition also provides opportunity for fundamental studies. In this work, we have examined the magnetic and magnetostrictive behavior of Pd-Ni, Pd-Co, and Pd-Fe alloys over the entire composition range. Alloy sample rods were prepared by arc melting and casting. X-ray diffractometer was used to obtain lattice parameter data. Magnetostriction was measured along the rod axis using strain gages. Magnetic properties were measured using a vibrating sample magnetometer.

Jan 1, 2005

By I. S. Blair

The introduction of the 36 MVA smelting furnace at Mufulira, and the experience gained during the first five years of operation have been described previously (6). Based on this experience the furnace was rebuilt in 1977., Details of the modifications made during this rebuild are described. Subsequent to the rebuild, refractory failures, particularly in the electrode ring bricks of the sprung arch roof, continued to cause concern, and repair and improved roof control methods are described. Electrode breakages continued, but developments in casing design and electrode preparation have resulted in significant improvements. Modifications in the electric furnace gas handling system are outlined, together with details of further changes to be implemented in the near future. The systems developed for metallurgical control of the furnace and the thermo-dynamics of the process are discussed. The electric furnace at Mufulira is now operating at above design production levels, and has decisively justified the choice of this technology in situations with inexpensive electric power. The potential for further increases in production capacity from the Mufulira unit, and improvements in design for new units are discussed.

Jan 1, 1983

By A. Mukhopadhyay

Gas stirring, simultaneous arcing, chemical additions are some basic steps in the secondary steel making. From tap to team however, there are enough uncertainties and several in-situ decision making required to match the fmal composition and temperature in the given amount of processing time. Currently available control algorithms rely on overall material and heat balance coupled with a self-learning regression based tuning of model constants. In this paper we demonstrate the capabilities of Computational Fluid Dynamics (CFD) in modeling and analyzing the thermo-chemical aspects of secondary Steelmaking. These models take advantage of scientific and engineering advances in computational tools and provide almost real time speed of analysis. This can be a very effective tool for operator training, process debugging and improvement as well as new innovations. Keywords: Argon purging, Secondary steelmaking, Arcing, Ladle Furnace, Process Control.

Jan 1, 2003

By Toshiyuki Kawai

Copper concentrate smelting directly in P-S converters was started at Onahama Smelter in 1983. Thereafter, the tonnage of concentrate smelted through the P-S converters increased, such that by 2002, it equaled the tonnage smelted through the reverberatory furnaces. In 2003, 56% of the total copper concentrates treated at Onahama Smelter were processed directly through the P-S converters. Technical improvements are reviewed and advantages of direct smelting in P-S converters are reported.

Jan 1, 2005

By A. E. M. Warner

Inco Limited has long and extensive experience in converting nickel-copper primary smelting mattes over a broad range of nickel/copper weight ratios and combined nickel-copper-cobalt contents. At the Copper Cliff Smelter, the composition of the converter product matte has to meet the requirements of the matte separation process; at the Thompson Smelter, converter matte of a different composition is cast into anodes for nickel electrorefining; and in Soroako, Indonesia, a very low copper product matte is granulated for the Japanese market. Recently, Inco has conducted pilot plant testing of three possible nickel-copper matte continuous converting routes, namely flash converting, oxygen top blowing-nitrogen bottom stirring, and tuyere blowing. This test work has generated substantial new information on nickel-copper matte converting chemistry. This overview paper reviews the metallurgy of nickel-copper matte converting, in particular the behaviour of cobalt and the operating conditions required to meet the iron and sulfur specifications of the product matte. The relevant thermodynamic information is used to discuss the industrial data.

Jan 1, 2003

By Neng-Wen Yu, Shau-Jun Zhu, Ji-He Wei

The desulfurization process by powder injection and blowing in the RH refining of molten steel and its mechanism have been considered and analyzed. Based on the two-resistance mass transfer theory and the mass balance of sulfur in the system, a kinetic model for the process has been developed. The related parameters of the model, including the mass transfer coefficients and the effective amount of powder in the molten steel being treated for desulfurization, have been more reasonably determined. Modeling and predictions of the process of injecting and blowing the lime-based powder flux under assumed operating modes with the different initial contents of sulfur and amounts of powder injected and blown in a RH degasser of 300 t capacity have been carried out using the model. The relevant circulation rate of the liquid steel and the powder injection and blowing rate were taken to be 100 t/min and 150 kg/min, respectively. The initial contents of sulfur in the liquid steel to be treated and the amounts of powder injection and blowing were respectively assumed to be 0.007, 0.006, 0.005, 0.004, 0.003, 0.002 mass-% and 10, 8, 6, 5, 4, 3 kg/t-steel. The total treatment time for desulfurization under each mode was set up at 24 min, equivalent to eight circulation cycles of the liquid steel to be treated. The results indicated that the predictions made with this model are in good agreement with some data of the industrial experiments and practice. Injecting and blowing the lime-based powder flux with the composition of 85 mass-% lime (CaO) + 15 mass-% fluorspar (CaF2) of 3-5 kg/t-steel, it is possible to decrease the sulfur content in the molten steel to ultralow level below (5-10)x10·4 mass-% from (60-80)x 10·4 mass-%. The total treatment time needed will appropriately be 12-20 min. Intensifying the powder injection and blowing operation and increasing the circulation rate of the liquid steel may effectively' raise the rate of the process in RH refining. The model may be expected to offer some useful information and a reliable basis for determining the reasonable process parameters and help in optimizing the technology of desulfurization by powder injection and blowing in the RH refining of molten steel.

Jan 1, 2000

By E. V. Verhoej

The proposed EU directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment promotes the substitution of lead in consumer electronics to reduce emissions from lead in the end of life phase. In this paper, the consequences of substituting lead in solders is assessed using the Eco-Indicator-99 method for the examples. The base metal production system is considered as an interconnected network modeled dynamically in Simulink 4 and Matlab 6 (Mathworks Inc 2000), where the recovery and production of metal components of the assessed product partially overlap. This approach requires global modeling of metal production processes and mass balances and resulting allocation choices. It also reveals the susceptibility of LCA scores to different choices in the modeling and data availability and uncertainty. Besides the comparison between lead-free and lead-containing solders, other side effects are revealed. Lead is carrier material for the recycling and production of many co-elements in the interconnected production and recovery system. Substitution may have adverse effects such as temporary shortages of other connected metals that are often not considered in normal LCA assessments, thus leading to erroneous results. The suggested approach provides directions for including these extemal effects and for further assessment of the environmental effects of substituting lead. This paper shows that in order to assess the environmental aspects of metallurgy, dynamic modeling of the total system is required based on the fundamental thermodynamics in each metallurgical reactor, the basis of this dynamic model. With this the true environmental impact of metallurgy can be explained. In the case of lead free solder, it is shown that the mining of substitutes has a very much larger impact.

Jan 1, 2003

By Qiang Zhong, Bin Xu, Qian Li, Yongbin Yang, Tao Jiang

Viscosity of slag determines the production efficiency, energy consumption and distribution of elements between metal and slag, which is very important for pyrometallurgy. Slag of goldantimony ore blast furnace smelting has seldom been studied. In this paper, the viscosities of gold-antimony ore smelting slags of different composition have been studied by the rotating cylinder method. The results showed that, for a slag of 38.95% SiO2, 16.17% CaO, 25.97% FeO, 10.25% Al2O3, 5.17% MgO, the viscosity can be decreased by reducing 3.24%-8.5% SiO2 or increasing 3.31%-9.56% CaO content. Complex SixOy z- from SiO2 acts as the main cause for the high viscosity in a slag of high SiO2. The increasing of CaO causes the decreasing of the amount of SixOy z- and the O2- dissociated from CaO breaks the complex SixOy z-, which can decrease the viscosity. Viscosity of different composition slag in the appropriate range temperature can be calculated from the Arrhenius equation.

Jan 1, 2015

By Andrey V. Tarasov

To carry out a physicochemical substantiation of a transition to ?soft? modes of reduction of calcine obtained by desulfurizing roasting of nickel concentrate produced as a result of copper-nickel converter matte separation in a nickel anode production circuit, an analysis has been conducted of the macrokinetic behavior of actual calcine samples in the presence of gaseous H2-CO mixtures and solid reductant additives. Within a temperature range of 900°C to 1100°C the main regularities typical of the calcine reduction process with individual gases (H2, CO) also take place when using a gaseous mixture. Under the conditions of low-temperature (900°C to 1000°C) nickel oxide reduction with products of fuel oil conversion in the presence of coke, the role of the latter is insignificant from the technological viewpoint. As a result of the present investigations, we have obtained analytical expressions of macrokinetic parameters of the reaction interaction within the [NiO] calcine-H2-CO-C-CO2-H2O-O2-N2 system.

Jan 1, 2005

By Ralph H. Nafziger

The Bureau of Mines, in cooperation with the Idaho National Engineering Laboratory, has electroslag melted a V-5Ti-5Cr alloy using a fused CaF2, flux. The alloy is a candidate for use in future fusion reactors. One objective of this research was to evaluate the feasibility of the electroslag melting process in separating simulated radioactive isotopes from the V alloy to demonstrate recyclability. Small amounts of Ca, Y, and Mn were added as surrogates for radioactive isotopes. Results showed that this vanadium alloy can be electroslag melted satisfactorily. The impurities added intentionally were removed or decreased successfully. Among the major alloying constituents, Cr was retained but there were some Ti losses. The latter may be controlled with process refinements. This research suggests that the electroslag melting process could be a suitable method for recycling V alloys after use in future fusion reactors, or for processing other reactive metal alloys with more immediate applications.

Jan 1, 1996

By S. Yabe

The reinforcement of the annual copper production capacity to 330,000 metric tons has been attained at Saganoseki Smelter & Refinery in 1991, which is one of the largest and most efficient custom smelters in the world. Many operational improvements and technology developments have realized the increase of smelting and refining capacity without adding main facilities to the existing process. The blister copper refining and anode casting process is composed of two 400 tonnes anode furnaces and one double-wheeled casting machine with the capacity of 80 tonnes per hour. The great innovations in this process such as the finding of essential issue on the extending of anode-mould life and the development of a new anode-mould casting machine have raised the operation efficiency by 14% Now, the process is producing 38,500 tonnes per month of best quality anode in well- controlled working condition, and anode productivity per worker increased by 52%. The progress in extending anode-mould life, the mechanism of the new anode-mould casting machine and the increase of efficiency in butane reduction, that were the principal parts of many technological improvements, are described in the present paper, including some operation results.

Jan 1, 1993

By Sergio N. Monteiro

Natural lignocellulosic fibers are successfully replacing synthetic fibers in many engineering applications. In addition to well-known conventional lignocellulosic fibers, others with promising properties are now being considered. The present work investigated the mechanical and structural characteristics of a relatively high strength fiber, curaua (Ananas erectifolius) from the Amazon region of Brazil. The results obtained from tensile tests confirmed the superior strength while scanning electron microscopy (SEM) analysis displayed features that justify the possibility of using the curaua fiber as an effective reinforcement for polymeric composites.

Jan 1, 2006

By Neil E. Ryan

Because of their chemical reactivity and affinity for oxygen, rare-earth elements are difficult to extract, and due to their close chemical similarity, it is an exacting task to separate one from the other. Nevertheless, these same characteristics can be used to benefit other metals by enhancing their resistance to high-temperture oxidation/corrosion and by inhibiting their corrosion in aqueous environments. This paper gives an overview of the use of rare-earths: [a] as alloy additions, [b] in coatings, and [c] when added to hostile environments, to retard rates of high- temperature oxidation and inhibit aqueous corrosion.

Jan 1, 1992

By Rak-Jun Choi

Plasma-induced damage of InGaN/GaN multiple quantum well (MQW) light-emitting diodes (LEDs) has been studied in terms of forward turn-on and reverse breakdown voltages, together with etch rate and surface morphology. The physical degradation of sidewall along with rough surface morphology of n-GaN caused by increased ion scattering induced the deterioration of the forward and reverse voltages. It was found that the turn-on voltage is sensitive to the surface roughness of the etched n-GaN and the breakdown voltage is strongly affected by the sidewall contamination. Annealing under nitrogen after the mesa etching improved the electrical properties of the InGaN/GaN MQW LEOs. Efficient blue light-emitting diodes (LEOs) were fabricated using InGaN/GaN triangular MQWs. The LEOs with triangular QWs showed a lower operation voltage and 2.4 times higher light output power than those with the rectangular MQW LEOs at 20 rnA and 20 "C. The intensity of electroluminescence (EL) at 20 mA was almost independent of ambient temperature in the triangular QW LEO, but decreased substantially in the rectangular one.

Jan 1, 2003