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By Y. H. Liu

Several foaming aluminum samples of different density were prepared in a semi-industrial scale experimental system. Their properties such as the energy absorption characteristics, mechanical properties, heat conductivity and acoustical properties were measured. The results showed that the foaming aluminum with a density of 0.5 to 0.6 g/cm3 has the best energy absorption and this makes it suitable as the ensuring bar of the automobiles and also as a cushion material for the engine. The foaming aluminum with a density of 0.25 to 0.4 g/cm3 has the best acoustical properties and heat conductivity resistance, which is suitable for the door filling material, the ceiling and the partition of the car engine.

Jan 1, 2003

By Anna Franzkowiak, Dean Gregurek, Alfred Spanring, Angelika Ressler

In order to determine the most suitable refractory products and improve the lining lifetime for the diverse furnaces used in the nonferrous metal industry, corrosion tests are performed at RHI’s Technology Center. The practical facilities include the cup test, induction furnace, rotary kiln, and drip slag test described in this paper, which enable a comprehensive understanding of the chemo-thermal brick wear on a pilot scale. The corrosion trials are performed with actual slags generated during operations at a customer’s plant. To determine the highest influencing wear parameter, every single test is combined with a detailed mineralogical investigation and thermochemical calculations performed using FactSage. Based on the results, tailored refractory solutions for the nonferrous metal industry can be provided in combination with trials conducted at the customer’s site.

Jan 1, 2014

By Nourreddine Menad

Plastic materials have been associated with electric and electronic applications since the early days of the electrical industry. Plastics can amount to 30 percents of the scrap mass. Generally, they are treated with flame retardants such as halogenated ones and they can result in different toxic chemical compounds. These plastics can be used as combustibles in the recovery of copper and precious metals. However, during their combustion, halogenated flame retardants can produce dibenzo-p-dioxins and dibenzo-furans. The estimated thermodynamic data of several organic compounds resulting from combustion of electric and electronic scrap, have been used in conjunction with the program HSC to calculate the conditions for dioxin and furan formation. The results show that the formation of the dioxins is dependent on the quantities of carbon, hydrogen, chlorine and oxygen reacting in a given system, as well as on parameters such as temperature and pressure.

Jan 1, 1998

By I. Gaballah

Spent hydrorefining catalysts may contain 4 to 6 % of COO and/or NiO, 8 to 16 % of Moo3 and up to 10 % V205 generally supported by alumina. Raw samples are roasted in order to eliminate carbon, sulfur and hydrocarbons contained in the spent catalysts. The roasting optimum temperature and time are 500 "C and 7 hours. Selective chlorination of roasted samples with Cl2 + air, Cl2 + N2 and Cl2 + CO is investigated in order to recover the valuable metals. Depending on the chlorination it is possible to recover more than 80 % of the Ni and Co about 95 % of the Mo and up to 80 % of vanadium compounds. Cobalt and nickel chlorides are obtained by leaching the chlorination residues' by acidified water. Molybdenum and vanadium chlorides and/or oxychlorides are obtained by selective condensation from the vapor phase. The chlorination of the catalyst support, Al2O3, can be limited to less than about 5 %. Besides the reaction temperature and time, the oxygen partial pressure of the chlorinating gas mixture appears to be the key factor for the reactions' selectivity.

Jan 1, 1993

By James J. Komadina, Robert R. Beebe

"Heap leaching of gold ores has enjoyed wide acceptance in the arid and semi-arid regions of the western U.S., Australia and South America. There are areas, however, where cold weather or excessive precipitation can limit the usefulness of heap leaching. Even in Nevada difficulties can be encountered which call for special operating procedures.The paper discusses the general climatological limitations and some of the techniques used to extend heap leaching into colder conditions. A case history of the Cripple Creek and Victor Gold Mining Company operation in Colorado examines 'valley-fill"" technology as an ideal cold-climate solution, where topographical conditions permit.AcknowledgementsThe authors gratefully acknowledge the management of Independence Mining Company for their permission to present this paper. The contributions of Golder Associates; Pikes Peak Mining Company Environmental Affairs Department staff, and the Colorado Department of Mines and Geology were all invaluable in successfully concluding this project.BackgroundWhen heap leaching of oxidized gold ores was introduced in the rnid-1970s it was aimed at large tonnages of low-grade material which could not, in general, be developed via conventional milling. Normally, the reasons for this were economic rather than technical: capital and operating costs for milling were simply too high. At first, grade was almost the only criterion, but deposits too small to justify milling were also potential targets for heap leaching.Renewed interest in gold was centered in the western United States and Australia, where exploration for milling-grade deposits had never really died. When heap leaching came along, it was in these areas that the first developments took place. Coincidentally, these same areas were favorable for heap leaching: climates were temperate for most of the year and competing land uses were limited. Even so, in the western United States in particular, winter temperatures were low enough to complicate operations. Precipitation was less a problem, although heavy snowfalls could periodically interfere as well."

Jan 1, 1997

By Sarel Johannes Francois Gates, Ida Kero, Yan Ma, Gabriella Tranell

During the tapping and casting of manganese ferroalloys, fumes are generated and released to the working environment. The fumes are mostly composed of metallic oxides generated due to reaction between high temperature molten metal and ambient oxygen in the air. From an environment perspective, it is important to limit these emissions. However, to do so, it is important to understand fuming mechanisms and kinetics as well as fume compositions, i.e. element behavior during the oxidation process of liquid manganese ferroalloys. Silicomanganese alloys are composed of aminimum of 65 wt% Mn and 17 wt% Si, 2 wt% C as well as minor and trace elements. These elements include Fe, Mg, Al and other elements originating from ores and reductants. Trace elements behavior in fume from liquid silicomanganese generated under an impinging air jet in the temperature range of 1450–1700 °C has been investigated in this work. The thermodynamic and kinetic conditions governing the generation mechanisms are discussed.

Mar 1, 2017

By Anil Saigal, Jr. Fuller, Said Jahanmir

"All-ceramic crowns, including glass-infiltrated spinel composites, are coming into widespread use because of their superior aesthetics and chemical inertness. This study investigates the residual stresses that are developed in these composites as a result of cool down from the glass-infiltration temperature to room temperature due to slight mismatch in the coefficients of thermal expansion and its effect on the mechanical behavior of these composites. Two-dimensional finite element simulations were performed using an object oriented finite element program OOF. The OOF program is a combination of two programs. The first program, PPM200F, is designed to read an image file such as a micrograph. The individual pixels that constitute the micrograph may be collected into groups and their material properties assigned. PPM200F is then used to create the finite element model/mesh that OOF then reads. The average residual stresses are found to be tensile in the spinel matrix and compressive in the infiltrated-glass. There is large variation in residual stresses and strains from location to location with presence of locations at which the glass is under tensile stress. The crack initiation and initial propagation in glass-spinel composites is at the glass-spinel interface in both the glass and the spinel. The presence of residual stresses can lead to lower crack initiation stresses and degrade the mechanical properties of the composites.IntroductionGlass-infiltrated spinel ceramics are in clinical use as core materials in all-ceramic crowns and as inlays and onlays (1-3). Advantages of ceramic composites include near net-shape forming with high strength in the infiltrated state. Besides, spinel is quite translucent and may potentially be used without a veneer. However, these ceramic composites are subject to damage accumulation from repeat oral contact loading and often fail after a few years of use (4). This paper examines the residual stresses that are developed in these composites, after cooldown from the glass infiltration temperature to room temperature, due to the slight mismatch in the coefficients of the thermal expansion of the two phases."

Jan 1, 2001

By Stavros A. Argyropoulos, Michael Trovant, Norman J. Goudie

"Two studies were carried out to estimate the thermal resistance of various interfaces using experimental and computational techniques. Three types of interfaces were examined. The first study investigated metal-mold interfaces, and the second study focused on metal-metal and metal-oxide interfaces.For the metal-mold interface, the air gap size was measured and subsequently correlated with the interface thermal resistance. The procedural details are outlined for the development of a correlation which predicts thermal resistance as a function of air gap size.Investigation of the metal-metal and metal-oxide interfaces employed data from a series of experiments as input into a model, which solved the inverse heat conduction problem in terms of a resistance estimate. These experiments, involved dipping a cold cylindrical metal into a liquid metal or liquid oxide, respectively. Under these conditions, a shell freezes around the cylindrical addition and a thermal resistance develops during the time period which shell exists . The Heat Transfer Coefficient (HTC) at the addition shell interface differs significantly among the various types of metals and oxides used. In the case of an oxide shell, the (HTC) is about an order of magnitude lower than the (HTC) of the metal shell.INTRODUCTIONIn many metals processing operations there is a need to estimate the thermal resistance at metal-metal, metal-oxide, metal-mold interfaces. This need was further intensified with the recent proliferation of mathematical models, which predict various transport phenomena events. There are many factors which can influence the magnitude of the interfacial thermal resistance. Some of the factors, among others, are as follows: contact temperature, metal thermal conductivity, apparent contact pressure, surface roughness, interstitial gas conductivity, and interstitial gas pressure.In this paper, two studies are reported on the estimation of thermal resistance. The first involves, the development of heat transfer coefficient-air gap relationships at the metal-mold interfaces. The second includes, estimations of thermal resistance at the addition-shell interface. The former case is encountered in the metals solidification and the latter during the melting and/or dissolution of additions to liquid metals or slags."

Jan 1, 1999

By A. S. Block-Bolten

Two innovations in nickel-arsenic separation have been studied on a laboratory scale. The first requires only a nitric acid atmospheric leach without preliminary roasting and leads to favorable final conditions for precipitation of arsenic as highly stable FeAsO4, The second is an NaOH-H2O2 pressure leach which is an alternative to the known NaOH-O2 pressure leach. Either method offers the possibility of rapid and efficient separation of nickel from arsenic and is applicable, for example to the high grade niccolite deposits in the Great Slave Lake area of northern Canada.

Jan 1, 1982

By Kenneth L. Driggs

The 1988 shift in primary smelting facilities from low grade matte (35%) reverberatory furnaces to high grade matte (63%) flash smelting heavily impacted a very stable and successful converter operation. Low matte grade converter campaigns averaged 36,000 short tons of copper and revert production/consumption was in balance. The conversion to high matte grades necessitated oxygen enrichment of converter blast and revisions in operating practices. After two years of operational development, campaign life has risen to over 40,000 short tons and revert production/consumption is again in balance.

Jan 1, 1991

By D. R. Kreuzer

The sulfide smelting industry is striving for up-scaling their operations by increasing the throughput and efficiencies of the furnaces. The physical phenomena related to refractory materials prevailing in smelters and furnaces are highly complex. The refractory materials are exposed to fairly high temperatures, thermo-mechanical stresses, penetration of pores, erosion and chemical corrosion. The application of numerical simulation tools is needed for the refractory engineering task to consider those phenomena and to evaluate the impact of operational regimes on the refractory design and finally on the integrity of the furnaces. The work discusses case studies of simulations addressing problems and questions related to the refractory design process. Practical simulation approaches which employ simplified models are introduced as the engineering process demands results in a reasonable time.

By Ben Q. Li

An efficient numerical algorithm for solving steady state heat transfer and solidification problems is described. The algorithm is of boundary integral type and is based on the formulation of the field variables along the boundary of the domain of interest. Compared with the familiar domain-based methods, such as the finite element and finite difference (or finite volume) methods, this boundary-based method has an advantage of solving fewer unknowns and hence has a potential for reducing computational time significantly. Another and yet more important advantage of the present algorithm is that it is a stable scheme and is not prone to numerical oscillations resulting from convective effects, as often encountered in the domain-based methods. Therefore, no numerical or artificial diffusion (such as streamline upwinding) is necessary. Numerical examples are presented that are drawn from processing systems for producing aluminum-based materials.

Jan 1, 1994

By Sylwia Zymankowska-Kumon, Rafal Danko, Józef Danko, Mariusz Holtzer

"Burning of ceramic materials is carried out at temperatures 900+ 1300°C, in dependence of the required functional properties. The Faculty of Foundry Engineering together with the Faculty of Material Engineering and Ceramics developed the technology of production of burned ceramic materials with using spent moulding and core sands. The mentioned above waste materials of the foundry industry fulfilled -in plastic masses intended for obtaining ceramic materials -the role of the addition weakening clay raw materials. The laboratory investigations were fully verified by the results of industrial tests. It should be pointed out that none negative effects were observed at the stage of mixing raw materials and preparation of plastic masses. The measurements of exhaust gases emissions performed during burning the products containing spent moulding sands as well as during the normal production did not exhibit any significant differences, which could have indicated the harmful impact on the natural environment.IntroductionSands are used by the foundry industry to make metal casting molds and are a mixture of silica sand, bentonite clay and carbonaceous additives or resins. During the casting process, the molten metal cause thermal decomposition of carbonaceous additives or resins, which results in the formation of potentially hazardous organics, that are emitted to the atmosphere and condense in the molding sand. Each year the U.S. foundry industry landfills about 10 million tones of sand because it is no longer suitable to make metal casting molds. A large high-silica sand content in spent foundry sands (SFSs) generates rational premises for their reuse in other than foundry practice fields. Efforts to divert the SFSs from landfills and encourage their beneficial use in manufactured soils, geotechnical applications, the construction industry (road construction, highway construction), the building materials industry (cement, bricks, limestone manufacture), in the filling of mining cavities or in landfill construction (roads on landfills, permanent covers) are make [1-7]."

Jan 1, 2013

By Wade L. Karlsen

"Revision surgery to replace joints in the human body requires materials that are strong, long-lasting, and biocompatible. Metallic implants made of cobalt-chromium-molybdenum alloys are already popular because of their proven corrosion and wear resistance properties, but there is an on-going effort to economically improve their performance. Alloying with inert nitrogen can enhance the mechanical properties of the alloy, enhance its corrosion resistance, and elevate the temperature at which the metallic implants can be thermally treated, without increasing the threat to the human body. The current work has produced a high-nitrogen Co-Cr-Mo alloy through HIP consolidation of metal powders that have undergone nitriding in a mechanically fluidized bed. The already fine microstructure of the powders combined with the increased nitrogen content resulted in significant property gains in the consolidated materials.IntroductionMetallic implants made of cobalt-chromium-molybdenum alloys are already popular because of their proven corrosion and wear resistance properties, but there is an ongoing effort to improve their performance. Research on a Stellite 21 cobalt-chromiummolybdenum alloy has shown that nitrogen alloying can be desirable from several standpoints [l]. Firstly, it has indicated that nitrogen can enhance the mechanical properties of the alloy, which could allow more demanding implant designs. The same work also demonstrated that nitrogen can elevate the temperature at which the metallic implants can be thermally treated, which is desirable in situations in which surface textures are to be sintered to the implant to enhance its fixation properties. Finally, that research work discovered that, not only does nitrogen not harm the corrosion resistance of the cobalt-chromium-molybdenum alloys, but it may in fact enhance it. Combining this with the fact that small amounts of nitrogen are not considered a threat to the human body, makes nitrogen alloying an attractive alternative for enhancing the properties of Co-Cr-Mo."

Jan 1, 2000

By Steven R. Izatt

IBC Advanced Technologies, Inc. (IBC) has developed a mercury selective product, which can be used by sulfuric acid producers as either a polisher, or as the primary technology for mercury removal from sulfuric acid. The Molecular Recognition Technology (MRT) separations material selectively binds Hg2+, and to a lesser extent Hg+, out of concentrated sulfuric acid. Mercury output levels of less than 0.1 ppm can be attained by the MRT system. Pilot plant tests have been successfully conducted at base metal smelting operations. A large-scale commercial plant is due for commissioning in 2003. Results from these projects will be discussed.

Jan 1, 2003

By R. Singh, C. Gong, J. Chaudhry

"Metalorganic chemical vapor deposition (MOCVD) is an ideal technique for the deposition of conducting and non-conducting oxide based thin film materials. In this paper we have presented a study of photo assisted MOCVD for the low temperature deposition of a number of oxide based advanced materials. We have used incoherent light sources as the source of optical and thermal energy in our MOCVD system. The vacuum ultraviolet (VUV) and ultraviolet (UV) photons can enhance the surface reaction of the absorbed molecules through the perturbation of the electronic state of binding between the absorbed molecules and the solid surface. Unlike plasma process, no surface damage is expected and high quality materials have been deposited. At a given substrate temperature, the performance of deposited film depends on the lamp configuration.INTRODUCTIONMetalorganic chemical vapor deposition (MOCVD) has become the standard manufacturing technique for the deposition of large area thin films of compound semiconductors. l.(.w-cost, high crystalline quality, atomically clean and sharp interfaces, atomic layer epitaxy, high throughput rates and potential for direct writing are some attractive features of MOCVD. Due to a number of potential advantages mentioned above, MOCVD is considered as an ideal technique for the deposition of various electronic and optical materials for a wide variety of applications. Rapid isothermal processing based on incoherent radiation as the source of optical and thermal energy is emerging as the key low thermal budget (integral of processing time and temperature) processing technique for the fabrication of current and next generation of microelectronic and optoelectronic devices and circuits [1]. In this paper we have demonstrated that the design of the lamp assembly plays an important role in determining the properties of the materials deposited by RIP assisted MOCVD. We have studied the growth rates, structural properties and electrical properties of Y2O3/Si structure. At a given substrate temperature, best results are obtained for the lamp assembly that provides maximum number of VUV and UV photons."

Jan 1, 1994

By Rejane Tubino Geyer

The volume of electric arc furnace (EAF) plus oxygen (BOF) slag produced yearly in the world is about 84 million ton. Because of this, the study of recycling processes as a way to solve the storage problem of these slags rise in importance. There are, however, some inconvenients on using this byproduct: lime, which takes part of the process of steel production, remains as a non-reactive raw product in the slag. Since lime reacts in presence of humidity, forming expansive compounds, slag use is strongly limited. There are some utilizations for the electric arc furnace and oxygen slag in the Civil Construction Industry, mainly as base, subbase and asphalt covering in highways. However, independently of the type of recycling, a period of "cure" of about six months is necessary. Because of this slow cure process this byproduct may turn non-competitive in some regions if compared, for example, with the natural aggregate. The objective of this work is to present the flowsheet of the slags production as a residue both at the electric and oxygen steel plants and, through a bibliographic review, to analize the possibilities and limiting factors for the use of steelmaking slags in the Civil Construction Industry.

Jan 1, 1996

By Thomas Niehoff

Many industrial processes require energy. Energy is required for melting or heating purposes. The heat can be generated by electrical heating or combustion/oxidation of hydrocarbons. Oxygen supports the combustion process. Oxygen is naturally contained in air with about 21 vol.-percent. The use of technical oxygen will allow an increase to the natural oxygen concentration of combustion air. Altering the combustion process by increasing the oxygen content has various effects. These effects are described and analyzed with regard to heat transfer, emissions and energy consumption. Industrial processes requiring oxyfuel are described and discussed regarding energy aspects.

Jan 1, 2008

By Dong Joon Min, Joo Hyun Park, Mi Sun Choi, Jae Hong Shin

Sublimation of ZrCl4 is important for the production of nuclear grade metallic Zr in Kroll’s process. The sublimation kinetics of ZrCl4 was investigated by TGA under both isothermal and non-isothermal conditions. The sublimation rate of ZrCl4 increased with increasing temperature under isothermal conditions. ZrCl4 sublimation was confirmed to be a zero-order process under isothermal conditions, whereas it was first-order kinetics under non-isothermal conditions. The activation energy of ZrCl4 sublimation under isothermal conditions was 21.7 kJ/mol. The activation energy for non-isothermal sublimation was 101.4 kJ/mol and 108.1 kJ/mol with the Kissinger method and Flynn- Wall-Ozawa method, respectively. These non-isothermal activation energies were very close to the heat of sublimation (103.3 kJ/mol). Sublimation occurs by two elementary steps: surface reaction and desorption. Therefore, the overall activation energy of ZrCl4 sublimation is 104.8(±3.4) kJ/mol. The activation energy of the surface reaction and desorption steps are proposed to be 83.1 kJ/mol and 21.7 kJ/mol, respectively.

Jan 1, 2014

By James R. Craig

The General Image Processing System (GIPSY) is being employed for the quantitative textural analysis of complex sulfide ores from the Southern and Central Appalachians and for the determination of liberation characteristics of the mineral constituents during grinding. Optical images from a microscope-mounted TV camera or from 35mm film are converted into digital images which are subsequently analyzed by GIPSY, a transportable image processing software package. Properties measured by GIPSY include spatial distribution of mineral constituents, grain sizes, grain shapes, grain orientation and mineral co-occurrences.

Jan 1, 1982