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By Hiroyuki. Fukuyama

The pseudo-binary phase diagram of the cuspidine (3CaO2?SiO2?CaF2) - CaF2 system has been studied by electron probe microanalysis (EPMA) and X-ray diffractometry (XRD). To prevent fluorine loss in the form of a HF gas by a reaction of CaF2 with water vapor at elevated temperatures, the equilibrium experiments were conducted with the sample hermetically sealed in a platinum tube. By employing this technique, it was successfully revealed that cuspidine exists as a stable phase and congruently melts at 1684 ± 1 K, and the cuspidine - CaF2 system presents a simple eutectic type of phase diagram, of which eutectic temperature has been estimated to be around 1540 K, corresponding to the composition of 40 mass% 3CaO?2SiO2 - 60 mass% CaF2?

Jan 1, 1999

By W. Y. Kim, K. H. Song, K. Nakata

"The present study was carried out to evaluate the mechanical properties of friction stir welded Inconel 600/SS 400 lap joints. In this process, friction stir welding (FSW) was performed at a tool rotation speed of 200 rpm and welding speed of 100 mm1min, and argon gas was utilized to prevent surface oxidation during the welding. Application of FSW notably decreases the grain size of Inconel 600 alloy from 20 µm in the base material to 8 ~ in the stir zone. However, the grain size of SS 400 in the weld zone was slightly coarsened, when compared to the base material. Also, the hooking in the advancing side and the intermetal1ic compounds (M7C3) in the weld interface between Incone1 600 and SS 400 were well formed. These intermetallic compounds and hooking were effective to increase in mechanical properties such as tensile and peel strengths.IntroductionFriction stir welding (FSW), applicable welding process at solid state, has several advantages in defect suppression such as blow hole, segregation and cracking which mainly occurs in fusion welding [1, 2]. Notable grain refinement in the stir zone due to FSW can expect the outstanding increase in mechanical properties of the welds. In constructing the chemical and power plants, Ni base superal10ys have been used in many parts, moreover, fusion welding as construct method, such as gas tungsten arc welding, electron beam welding and laser welding, has been mainly used [3-5]. However, fusion welding has a limit in an increase in chemical and mechanical properties in the welds. Lately, Ni base superalloys to which FSW applied have been reported with notable enhancement in mechanical properties, which resulted from refined grains in the welds [6-10]. These researches showed the possibility in applying the FSW, directly."

Jan 1, 2012

By O. I. Platonov

The experience that has been gained by MMC ?Norilsk Nickel? at its Trans-Polar Division (PD) operations since 1981 in the field of recovery of elemental sulfur from off-gas generated by the Vanyukov and flash smelting through its reduction by natural gas is briefly outlined in the present paper. The key challenge the operators treating off-gas originated from autogenous smelting are usually faced with is the presence of sulphur trioxide in it. Furthermore, air inflows along the entire gas flue increase oxygen concentration in off-gas, thus leading to over-consumption of the reducer (natural gas). Another issue attached to the methane technology is a low yield of hydrogen sulphide largely preventing efficient downstream Claus conversion of the gas. The new flowsheet for treatment of autogenous smelting off-gases including dry dust-cleaning followed by the gas reduction in homogenous reactor developed by OAO Gipronickel Institute on the basis of industrial-scale production of elemental sulfur in Norilsk is presented.

Jan 1, 2006

By Tang Chaobo

Employing manganese carbonate ore and zinc oxide dust as material, Mn-Zn compound oxide powder for soft magnetic ferrite was prepared by a serial methods, as follows: leaching by using sulfuric acid, removing aluminium and silicon by neutralization and flocculation method, using ammonium bicarbonate to co-precipitating Mn and Zn, calcinations and washing to removing impurity content. The optimal technical condition was obtained by experiments. The difficulty of removing impurity such as Si, Al, Ca, Mg, from leaching solution was solved. The impurity content in the production meets with the preparation standard of high quality soft magnetic ferrite. The compound oxide powder obtained in the experiment was made into lower power loss magnetic ferrite, the quality of magnetic ferrite meet the standard of PC40 which was established by TDK corporation.

Jan 1, 2006

By T. Manlyama

The Tamano Smelter of Hibi Kyodo Smelting CO., Ltd. went into operation in 1972. The Flash Smelting Furnace that was originally adapted was equipped with electrodes that were attached to the settler substitute of the slag cleaning furnace. Later the development of our own original coke combustion technology was promoted and a new Tamano Type Flash Smelting Furnace (T-FSF), without electrodes, was put into operation in 1988, T he technology of coke combustion and combustion the burner have continued to improve. As a result the copper losses in the Wag have been reduced as well as a stable operation has been achieved, Furthermore; this has been accomplished while increasing the concentration feed and the matte grade. The current objective is to continue to strive for high matte grade operation and to raise production efficiency while paying attention to the important subject of copper losses in the slag. In this report, the data related to the copper loss in the slag reduction are presented along with the influence of the thickness, settling time and coke. The recent operation conditions of the T-FSF are also presented.

Jan 1, 2003

By Peter Brown

The present work involves the study of Chemical Vapor Deposition (CVD) of silicon carbide from the methyltrichlorosilane (MTS) - hydrogen system. A computer program, SOLGASMIX has been employed to calculate the equilibrium compositions of the gaseous and condensed phases in the MTS - H2 system. The results indicate the range of parameters such as temperature, pressure and species concentrations, required to deposit the single phase Sic under thermodynamic equilibrium conditions. A mathematical model for describing the transport phenomena and the rate of deposition of Sic onto a thin rod in a vertically-oriented hot-walled CVD reactor has been developed. Exper iments were conducted using the same operating conditions as those used in the model in order to validate the mathematical predictions. The predicted rates of deposition were found to be in good agreement with those obtained experimentally. The model can be used to study the effects of various operating parameters on the rate of Sic deposition on a fiber.

Jan 1, 1992

By Denis Legault, Ghyslain Dube, Ronald Morin, Jacques Bonneau, Daniel Guay, Keith Annett, Raymond Breault

"·The total recycling of all the constituents present in aluminum dross is now an industrial reality for Akan. This is made possible by the combination of two patented processes: the Alcan plasma dross treatment process, operating since 1990 at its Guillaume-Tremblay Works, and the calcium aluminate fabrication process, operating at AlumiCa's new plant in Thetford Mines. The latter process uses the total non-metallic content of the dross, thus rendering possible the complete recycling of aluminum dross.After describing the plasma dross treatment process, this paper will present the calcium aluminate fabrication process and how both processes contribute to close the recycling loop. The characteristics of Nova!™ by-product will also be described, as well as how they contribute to make a calcium aluminate with chemical and physical properties that are highly sought after. This calcium aluminate, produced by AlumiCa, is marketed under the trade name Kwikflux®. AlumiCa's total production is presently sold to a number of steel plants worldwide."

Jan 1, 2000

By T. T. Natarajan, Nagy EI-Kaddah

"Numerical simulation of electromagnetic confinement systems generally requires large CPU time due to the strong coupling between the electromagnetic and the free boundary problems. The present paper examines the accuracy and the computational efficiency of the most common numerical schemes used in modeling such systems. Levitation melting was taken as a test case. In this study, a comparison was made between the finite element and surface integral methods for electromagnetic field calculations. The computational efficiency of Lagrange and the modified Hestenes methods for solving the free boundary problem were investigated. The convergence of the Lagrange method was found to be much faster than the modified Hestenes method. It was also found that finite element method not only gives accurate solutions, but faster convergence to the final equilibrium shape than the surface integral method. The applications and the limitations of these techniques in modeling electromagnetic confinement systems will be discussed.IntroductionIn recent years there has been a growing interest in the use of electromagnetic forces for confinement of molten metals as a means to eliminate molten metal contamination during melting and to improve surface quality of cast products. Continuous casting of metal without contact of a mold is now a reality, and is being commercially applied for casting of aluminum slabs /1/, and copper rods /2/. New applications of electromagnetic confinement in melting and casting include containerless melting (Magnetic Suspension Melting) /3/, edge containment in twin roll casting, and meniscus shape control in continuous casting of steel /4/.Modeling of confinement systems involves the determination of the electromagnetic field and the equilibrium shape. These two problems are strongly coupled due to the dependence of the field on the shape of the melt. While significant advances have been made in computational electromagnetics /5/, the application of developed computational techniques to electromagnetic confinement problems is not a simple task. The principal difficulty in using these methods is that the solution domain is not known a priori. due to coupling between the electromagnetic field and the free boundary problems. These two problems have to be solved simultaneously, leading to an iterative solution procedure. As a result, numerical simulation of electromagnetic confinement systems are computationally intensive with computational time at least an order of magnitude larger than the fixed domain problems."

Jan 1, 1994

By H. K. Lin

Thermodynamics of Cu-C1-H2O system and the kinetics of copper dissolution in cupric chloride solution were studied with emphasis on possible difficulties which may occur during copper electrowinning. E,-pC1 diagram of this system wasestablished. Equilibriumdistributionof various copper chloride complexes of different valent states at the presence of metallic copper was computed through the relations of the simultaneous equilibria. The mechanism-of copper dissolution in the cupric chloride solutions was proposed and the mechanism of copper electroposition was discussed. The researched results were used for guiding the investigation of copper electrowinning from cupric chloride solution.

Jan 1, 1991

By M. Mujahid, A. Maqsood, M. H. Asghar, K Iqbal

"Thin film multilayer anti-reflection coatings (Si02/Si/Si02) having thicknesses 286/571/143nm were deposited by RF magnetron sputtering deposition technique on 0.5mm thick Si(100)-substrates. Post-deposition annealing is also carried out in the temperature range 150-650°C for 4hr at the rate of 10°C /min. Si Optical window was designed at 4.21lm wavelengths and correlated with modeling software. The films are transparent in the 3-51lffi band of the electromagnetic spectrum, firmly adhered to the substrate. The prepared multilayer thin films are characterized optically and structurally using a spectrophotometer, an atomic force microscope, x-ray diffraction and a scanning electron microscope. Optical and structural characterizations show that the %transmittance is between 60% and 75%, no appreciable change in crystal structure and roughness of coatings vary between 9 and 25 nm when annealed in the temperature range of 150-650oC. Local elemental characterization on the surface of the thin film was carried out using energy dispersive spectroscopy. The quantitative result of energy dispersive spectroscopy has also shown that the ratio of Si to 0 on the film is 0.67: 1.IntroductionSi02 thin films have unique properties in the interfaces with Si and most studied materials in the field of microelectronics and optical devices [1]. Multilayer thin films are using nowadays in the design and fabrication of the shrinking systems with a variety of fields such as optoelectronic devices. The physical properties and parameters can be controlled at scales of microns down to nanometers by using RF magnetron sputtering system [2].Silicon and Silicon dioxide are used as coating materials [3]. These thin films are laid on top of each other in SiO2/Si/Si02 order by RF magnetron sputtering on top of a substrate as given in Table 1."

Jan 1, 2012

By Robert B. Haagensen

While light optical microscopy has long been employed by the mineral processing industry, there has been a tendency to shy away from its use for all but the most exacting purposes. Despite the usefulness of micros-copy in solving a wide variety of problems, the response to such work is often less than enthusiastic primarily due to time considerations. Microscopical techniques are therefore often relegated to the "ivory tower" and their direct and practical application to everyday problem solving over-looked. The purpose of this paper is to dispel such attitudes and promote a wider use of light microscopy. Several examples are given which point out the indispensib1e nature of optical microscopy as a rapid means of defining and solving problems in mineral processing. The application of other instrumental techniques to augment the information obtained is also discussed, particularly the value of the combined use of the optical microscope and electron probe micro-analyzer.

Jan 1, 1981

By Orion Ciftja, Arjan Ciftja

"The directional solidification method is routinely used to produce polycrystalline silicon, an important material for the photovoltaic (PV) industry. The form of the solid-liquid interface during solidification has considerable influence on the material quality. The dissolved impurities and the solid inclusions above the solidification front affect the interface and may cause interface breakdown. We investigate the effects of pushing and engulfment of silicon carbide (SiC) particles by the solidification front during directional solidification of silicon. We employ a 12kg directional-crystallization furnace to cast the molten silicon. We use upgraded metallurgical grade silicon with low concentrations of metallic impurities (< 5ppm) and a high content of carbon (700 ppm) present as SiC particles. Samples from the cast polycrystalline silicon ingots are investigated by light microscope. The expected interaction of impurities with the solidification front is investigated theoretically using empirical models. The data obtained from the models are in good agreement with the experimental results.IntroductionDirectional solidification is a well-known method for producing multi-crystalline silicon for the PV industry. In this method a planar front, achieved during solidification, results in a clearly defined interface between the solid and the liquid phase. The solubility of major impurities is higher in the liquid than in the solid phase. Therefore, directional solidification will work as a purification process where the impurities are retained in the liquid phase [1]. Apart from the process of removing the dissolved elements in molten silicon, the directional solidification plays also another role. It will interact with the solid particles that may be present in the melt. When a liquid containing an insoluble particle is solidified, three distinct interaction phenomena are observed: engulfment of particles, continuous pushing, and entrapment [2]. The term “engulfment” is used to describe incorporation of a particle by a planar interface, and the term “entrapment” is used for particle incorporation by a cellular or dendritic interface (see Figure 1) [3]."

Jan 1, 2014

By Kazuya Kitatani, Gen Sasaki, Naoto Ohta, Hideharu Fukunaga, Makoto Yoshida, Jin Pan, Kenya Nagahisa, Toshihiro Ishikawa

"A sintered SiC (Tyranno-SA) fiber-reinforced MAS glass matrix composite was fabricated by using a slurry infiltration method and hot-pressing. The microstructure and mechanical properties were investigated: To prepare the preform, the MAS glass slurry including a dispersing agent was infiltrated into a bundle of the fibers. The preform was then hot-pressed under the conditions of 1473 K, 30 MPa, 3.6 ksec. A unidirectionally-reinforced oxide matrix composite with 50% Vf. of the fiber and a density of 2.84 g/cm3 was obtained. As the mechanical properties at room temperature, the three-point flexural strength- and quasi-static adsorbed energy were 500 MPa arid 6,000 J/m2, respectively. Without graphite or an h-BN pre-coating on the surface of the fiber, pull-out and bridging of the fibers from the matrix was found, and this leads to a high value of the adsorbed energy. By TEM observation, nano-scale crystalline products were found between the fibers and the glass matrix. The push-out test reveals that this layer causes the appropriate debonding of the interface during the fracture process of the composite.Introduction It is known that the CFCCs (continuous-fiber-reinforced ceramic matrix composites) are characterized by their non-linear fracture behavior, which is' hardly found in monolithic ceramic materials. It is inevitable for the CFCCs to exhibit a large fracture toughness so 'that debonding of the fiber/matrix interface; pull-out and bridging of the fibers then' occurs during the fracture process. This series of fracture behavior is known as the so-called ""the mechanism of toughening of the CFCCs"". Thus, different from the MMCs in which strong interfacial bonding is necessary, the interfacial strength of the CFCCs has to be controlled. As techniques for controlling the interfacial strength, it is also known that both a CVD-graphite coating and an h-BN coating are effective to induce the mechanism of toughening[1,2]. In the case, of the Si-C-O or Si-Ti-C-O fibers/glass or crystalline oxide matrix composites, it is reported that the formation of the in-situ graphite layer, which is also effective to increase the fracture toughness of the CFCCs, is often found during the fabrication process such as hot-pressing. The lower the crystallinity of the Si-C-O fibers, the higher is the tendency to form the in-situ graphite layer as found by the chemical reaction between the fibers and the glass matrices[3-12]. On the-other hand crystallized stoichiometric 'SiC fibers are attractive for high temperature service because of the higher phase stability compared to the Si¬C-O or Si-Ti-C-O fibers. However, in the previous, studies, the mechanical properties and the interfacial chemical reaction of the crystallized SiC fibers / glass matrix Composites have still been unknown. In this study, a polycrystalline 'sintered SiC fiber-reinforced MAS glass composite was fabricated. The mechanical properties and microstructure were then investigated. The slurry infiltration technique followed by hot-pressing was used to prepare the composites. The formation of the in-situ graphite layer and the relationship between microstructure and mechanical properties at room temperature were examined by the TEM observation of the fiber/matrix interface."

Jan 1, 2000

By Paykan Safe

Computational Fluid Dynamic (CFD) modeling provides a powerful tool to assist with the design of ventilation and fume control systems in smelters and other high temperature metallurgical facilities. For this paper, this tool has been used to analyze the off-gas flow patterns exiting the mouth of a Peirce-Smith converter into a water-cooled hood and drop out box. The effects of various process and physical plant design parameters on process gas and fume capture and potential build up on the converter hoods was examined, and the optimum design and operating parameters were determined.

Jan 1, 2000

By Julian Szekely

A review is given of the current metals processing operations, where electromagnetic forces play an important part in affecting the performance of the system. These include arc furnaces, plasmas, the Hall Cell, electromagnetic stirring and others. These considerations will be extended to discuss what new frontiers may be breached by the intelligent application of electromagnetic phenomena. The topics discussed will include magnetic flow control, levitation melting and cold crucible melting and refining.

Jan 1, 1988

By Julie M. Melluish

The metallurgical response of the Point Leamington deposit has been studied. Two series of bench tests were conducted and various ore samples and flotation products were examined using image analysis techniques. The majority of sphalerite and chalcopyrite grains in this texturally complex ore were found to be smaller than 10 micrometres. Copper recoveries were low with losses mainly as fine inclusions in pyrite. Sphalerite recoveries were somewhat better due to a generally coarser habit. Gold and silver recoveries were also low and only solid solution silver was identified in the ore. The deposit shows poor economic prospects unless additional tonnage of high grade zinc ore can be delineated.

Jan 1, 1989

By A. De, J. S. Zuback, T. Mukherjee, T. DebRoy

For successful commercial applications of additive manufacturing, metallic parts need to be defect free, structurally sound and reliable. However, additively manufactured metallic parts are susceptible to distortion, lack of fusion defects and compositional changes. Methods to measure susceptibilities of various alloys to these defects are needed but not currently available. Here we show that the necessary theories can be developed based on a well-tested numerical heat transfer and fluid flow model and decades of research in the field of welding. The proposed theories are validated with experimental results reported in the literature.

Jan 1, 2016

By James T. Staley

Quenching and aging are critical processing steps used to produce precipitation hardenable aluminum alloy products. This work describes personal computer programs that employ models to predict certain properties after quenching and aging and graphically display them. One of the programs allows the user to predict the attainable strength and toughness of aluminum alloy products after an arbitrary quench. Another program simulates the changes in strength and electrical conductivity occurring during second-step aging alloy 7050-T7X products as a function of thickness, furnace temperature set point, and furnace characteristics.

Jan 1, 1993

By Don Eby

The application of electric arc furnace smelting of lead, antimony, and tin bearing slag from a reverberatory furnace will be discussed. The selection procedure for the 4.0 MVA electric arc furnace in Indianapolis, Indiana is presented. The design criteria for the transformer, electrodes, refractories and associated equipment is presented. The operation of the furnace including chaJ:9ing, bullion tapping, slag tapping, ventilation, slag composition, metal recoveries, and toxic leach results of thra.1 away slag are discussed. Flow charts and the equipment specifications are given.

Jan 1, 1990

By Laura Garcia H, Juan Carlos Gonzalez Islas, Luis Garcia Lechuga, Pedro Alberto Ramirez Ortega

"Electrochemical studies were performed to silver recovery from industrial wastes (radiographic films) on litanium flat electrode using a filter press-type electrochemical reactor with vertical orientation (known as REOV-01), as counter electrode was used a mesh-type DSA. Voltammetric studies were employed to fmd the current range under which silver reduction occurs. Using chronopotentiometric studies with controlled current, homogeneous deposits were obtained on the surface of the Ti electrode, to a current of -210 mA during 120 minutes to a constant linear flow velocity of 15 Lmin-1 was achieved 97% of silver recovery from industrial wastes. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy studies corroborated the presence of silver on Ti flat electrode. In addition, the silver concentration in the solution after the experiments was 1 ppm below environmental requirements. This indicates the viability of a filter press-type electrochemical reactor with vertical orientation (REOV-01) for silver recovery from radiographic filmsIntroductionIn recent years, the industrial sector has shown an increase in the use of silver due to new applications in different areas. In sectors such as photography, the consumption of silver has declined as a result of the boom in digital photography. However, the use of silver in radiographic applications has not shown greater variation (47.16 Moz), as the image quality is essential for diagnosis in various fields, such as medicine. All the silver used in photographic applications is discarded completely (solid or in effluent). At the present, several countries have been involved in silver recovering from industrial wastes due to the economic value and environmental impact they represent. The main source of silver recovery is the wastes generated by the photographic sector. Various technologies have attempted to recover silver contained in these wastes. However, they have not fully satisfied the requirements of maximum recovery, nor environmental level (less than 5 ppm) of silver in effluents [1,2]."

Jan 1, 2014