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By G. S. Hanumanth

Sedimentation of particles during the liquid metal processing of particulate metal-matrix composites can affect the homogeneity, and thereby the properties, of the cast product. A novel electrical probe has been developed to measure the in-situ volume fraction of ceramic particles in molten metal baths. Using this probe, sedimentation rates for 90 pm silicon carbide particles dispersed in molten aluminum A356 alloy were measured over a wide range of particle volume fraction, 0.05 to 0.3. The sedimentation rate was found to depend strongly on particle volume fraction; the time to clarify a 0.15 m depth increased from approximately 60 to 500 seconds as the volume fraction increased from 0.05 to 0.3. Measured sedimentation rates agree well with the predictions of a sedimentation model based on one-dimensional, two-phase flow theory in which the inter-phase drag function is derived from the momentum equation, utilizing the Richardson-Zaki Equation for sedimentation in aqueous systems. The implications for solidification are discussed.

Jan 1, 1993

By B. Thompson

"1. AbstractMagnesium alloys have been successfully recycled for decades and have won acceptance for use by die casters and most of the automotive industry. As the supply chain for magnesium and magnesium alloys continues to change, due to the consolidation of producers, it is essential that quality control methods be closely examined with each new supplier added. An examination of the various process steps that are needed to assure quality in the final product will be discussed thus giving a basis for the auditing of new magnesium suppliers.2. IntroductionMagnesium recycling in the past has been somewhat limited due to its use more as an alloying agent for aluminum based alloys and as a desulfurization agent in iron and steel than in more readily recycled structural products. Recycling efforts continue to improve as more production is finding its way into automotive structural components, hand tools, and a variety of computer and cellular telephone applications.With the closure of several large North American primary magnesium production facilities over the past decade we have only recently witnessed a tightness in supply that is driving magnesium prices significantly higher, nearly doubling the price in the last year alone. The rapid escalation in pricing will provide additional economic incentives to fully utilize recycling for the recovery of an even greater percentage of both old and new sources of magnesium scrap. Political pressure continues to intensify towards the secondary recovery of any and all recoverable resources of which magnesium recycling readily applies.Economics will also likely drive the development of new sources of magnesium production, both from primary and secondary production. As new sources of magnesium are offered to the marketplace the potential for product quality issues may increase. When considering any new raw material supplier a decision must be made as to the impact of defective material on the intermediate or finished product. Quality defects in magnesium ingot can result in a variety of appearance, corrosion, and even adverse structural effects in the finished product. The potential severity of the impact of defective raw materials on the finished product will determine and often justify a close look at any new supplier. An on-site audit of a new supplier of a critical raw material is often justified to ensure that an adequate quality assurance system is in place. We will now look at a number of key production points that should be examined during an on-site audit that have can have an impact on the overall quality of the finished product."

Jan 1, 2008

By Yue Tian, Shengqian Wang, Lifeng Zhang

This paper is to discuss the removal of non-metallic inclusions from molten steel using a high frequency magnetic field. In experiments, a certain amount of aluminum was added to the molten steel in a crucible to generate aluminum inclusions. A layer of aluminum clusters were observed close to the wall of the crucible after the electromagnetic (EM) field was imposed. Three dimensional EM field and fluid flow simulation were performed and showed that over 91% inclusions transported to the skin depth (2.31 mm) of the molten steel. The calculation of inclusion removal agreed well with the experimental observation. The separation mechanisms of inclusions from the molten steel by the high frequency EM field were discussed.

Jan 1, 2014

By Mark Khinkis, Huajun Yuan, Mark Zak, Yaroslav Chudnovsky, Aleksandr Kozlov

"An afterburner for green petroleum coke calcination in electrothermal fluidized bed was designed, fabricated, installed, and tested on a pilot fluidized bed calcination furnace. The experimental set-up comprised a combustion chamber, in which fine particles and volatiles of the furnace off-gas were fully combusted, and a cooler equipped to calculate the related heat recovery and losses. Off-gas composition was analyzed to evaluate the combustion process. The energy balance confirmed the potential to recover a large part of the heat value of volatiles and fme particles from the GPC. Potential future applications of the results are discussed.IntroductionGreen petroleum coke (GPC) is an oil refining byproduct that can be used directly as solid fuel or as feedstock for the production of calcined petroleum coke [1-2]. GPC contains a high amount of volatiles and sulfur. With coke calcination, the GPC is heated to remove the volatiles and sulfur in the calciner off-gas to produce purified calcined coke, which is used in the production of graphite, electrodes, metal carburizers, and other carbon products. Currently, more than 80% of calcined coke is produced in rotary kilns or rotary hearth furnaces. These technologies provide partial heat utilization of the calcined coke to increase efficiency of the calcination process, but they also share some operating disadvantages [3]. On the other hand, coke calcination in an electrothermal fluidized bed opens up a number of potential benefits for the production enhancement while reducing the capital and operating costs.The increased usage of heavy crude oil in recent years has resulted higher sulfur content in green coke produced from oil refinery process, which requires a significant increase in the calcinations temperature and residence time [ 4]. The calorific value of the process off-gas is quite substantial and can be effectively utilized for combined heat and power (CHP) production to complement the energy demand. Waste heat recovered from the product cooling could also contribute to the overall economics of the calcination process. Preliminary estimates indicated the decrease in energy consumption by 35-50% as well as a proportional decrease in greenhouse gas emissions. So, efficiency improvement of the coke calcinations systems is attracting close attention of the researchers and engineers throughout the world."

Jan 1, 2014

By Fathi Habashi

"Davy, Faraday, and Bunsen laid the foundation of electrometallurgy which had a· great impact on other areas of metallurgy. Electrometallurgy is presently dominated by the production of aluminum, the electrorefining of copper, and the electrowinning of zinc. It has also been successful in the electrowinning of copper from solutions obtained by leaching-solvent extraction. Electrowinning processes, however, are capital intensive. Improvement of the present technology should be intensely investigated especially when it is expected that such processes will increase greatly as a result of a shift from certain pyrometallurgical processes to pressure hydro metallurgy.INTRODUCTIONPyrometallurgy was used for thousands of years to produce copper and iron from their oxide ores!). Today it is still the only route to produce iron and steel and it is certain that it will remain so for many decades to come because pyrometallurgy is most suitable for the treatment of high grade oxide ores. Even when high grade iron ores are exhausted, it is possible to beneficiate the low-grade ores and produce pellets suitable for reduction in the blast furnace, which is a very efficient reactor, being a heat exchanger as well. Hydrometallurgy on the other hand can be traced to the time of alchemists in the Middle Ages when they were seeking to transmute base metals into gold, and thus were able to prepare many acids and bases which are the essential leaching agents."

Jan 1, 1997

By Frederico Muylaert Margem, Jarbas Bravo Neto, Sergio Neves Monteiro

"The mechanical behavior and the fracture characteristics of composites with DGEBA/TETA epoxy matrix reinforced with up to 40% in volume of continuous and thinner ramie fibers were evaluated by tensile tests. Specimens with selected thin fibers aligned along the tensile axis were room temperature tested to rupture. The fracture surface was analyzed by scanning electron microscopy. The results showed significant increase in both the ultimate tensile strength and the elastic modulus. The fracture analysis indicated the possible mechanism for the fiber/matrix interaction, which could be responsible for the composite performance.IntroductionThe fiber reinforced polymer composite emerged in the middle of last century as a versatile engineering material for applications requiring mechanical resistance in association with lightness. Its most commonly used example is ""fiberglass'', i.e., a thermoset polymer matrix composite reinforced with glass fiber. Indeed, ""fiberglass"" has a specific strength of the order of 500 MPa.cm3/g, which is the double of the strongest steels like the maraging. This motivated, at earlier times, ""fiberglass"" to replace many conventional materials including wood and natural fiber composites. Today, ""fiberglass"" has a wide range of uses from aerospace systems and appliances to sport and leisure components. However, its fabrication as well as those of any synthetic fiber such as carbon and aramid composites, requires a relatively large amount of energy. Presently, a growing concern exists regarding the consequences to the environmental by gases like C02 associated with both the energy consumption and the processing of synthetic fibers and their composites. These gases are well known responsible for global warming [1]."

Jan 1, 2011

By M. A. Barakat

Large amounts of zinc ash and flue dust containing more than 80 % zinc are accumulated during galvanization processes at the surface of molten zinc bath and in the chimney respectively. Pyrometallurgical recovery of zinc from both of the ash and dust samples has been carried out. The ash was sieved with the help of an industrial sieve shaker provided with mesh sieve having a pore size 0.9 mm. The oversize fraction cut (+ 0.9 mm) was melted at 550 °C under ambient conditions. The produced ingot (1) was analyzed whereas the coarse fraction of the produced slag (+ 0.9 mm) was treated as the coarse ash or added to it. The dust was enriched with suitable fluxing salt prior to heat treatment at 600 °C for 1 h. The produced ingot (2) was analyzed whereas the resulting slag was mixed with the fines of the ash and treated by hydrometallurgical processing to prepare valuable salts of zinc. Parameters affecting recovery processes such as time, temperature and flux percentage were studied. Results obtained revealed that the two prepared ingots (1&2) were successfully recovered with recovery efficiency amounts to =85 %. The obtained samples meet the standard specifications with relatively low price. Also in the light of the strict environmental regulations of pollution control, reuse of these wastes materials will help in keeping the environment clean.

Jan 1, 2000

By Fumito Tanaka

The Mitsubishi process is the sole pyrometallurgical process for the continuous production of blister copper from Copper concentrates and has been successfully operated around the world. The development of calcium ferrite slag (CaO-FeOx-Cu10), the so-called "C-slag", has enabled continuous converting from matte to blister copper in the commercial scale operations. Commercial interests in the slag led to many papers over the CaO-FeOx slag. However, Cu2O bearing slag has not been studied well due to experimental difficulties. The authors have quantified the thermodynamic properties of the CaO-FeOX-Cu2O system. The results have been utilized to analyze various issues related to the converting furnace, such as the magnetite precipitation from the slag or from blister copper and to develop better controlling criteria for the continuous converting operation. -

Jan 1, 2003

By W. G. Davenport

This chapter examines three minor influences on flash smelting's industrial oxygen and oil requirements, i.e.: (a) recycle of molten converter slag to the flash furnace (b) gangue oxides and carbonates (e,g, Ah03, CaC03) in the flash furnace feed (c) minor sulfides (e.g. NiS} in the flash furnace feed. It then examines the. sensitivity of our flash furnace calculations to previously ignored aspects of smelting chemistry -Cu, S and Fe304 in slag and 0 in matte.

Jan 1, 2001

By R. Togashi, T. Aichi, T. Yamada

"A new automatic material- handling system for cathode transportation has been developed. The first system went into service in August 1994 and the remains will be operational subsequently.Because of the complex cell-layout and the number of cells in each row, the critical part of this work was achieving a planned cycle time. This cycle time is determined by the power costs.The central monitoring system for machine operation was started in June 1996, using original application software based on MICROSOFT EXCEL ® on WINDOWS 95® .As a result, only one person is now required to operate both a crane and a stripping machine for one row of about 50 cells.INTRODUCTIONMainly due to the strong yen and the relatively low price of metal, the zinc refineries in Japan are being forced to reduce production costs again and again.The trend of lijima's production costs is shown in Figure 1.[1] The ratio of labor costs becomes gradually higher. Therefore it is effective to reduce the labor costs in order to reduce the production costs. In Japan, electricity cost during day time is too high to produce zinc at a reasonable cost, that is why the actual production is far from the capacity of production at a cell house. That means a plant in Japan has the disadvantage of relatively low productivity for cell house operation.Saving labor costsSome automatic cranes have been applied to save labor costs for cell house operation in the world. In consideration of the mentioned low productivity, the installation of an Automatic Cathode Transfer (ACn system for transportation of cathodes was planned without changing the present cell house and stripping machines to lower the investment costs. The ACT system must keep up with the stripping machine which is able to strip deposit zinc from a cathode sheet at the rate of 6 seconds.The fifth ACT system of seven was installed in August 1996 and the last one will be operational subsequently."

Jan 1, 1997

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 Jie E. Zhou, Yu U. Wang

"Development of crystallographic texture in polycrystals during templated grain growth process is studied by phase field modeling and computer simulation. To characterize the grain texture development, X-ray diffraction peak intensities are computed for the evolving grain structures as simulated by the phase field model, based on which Lotgering factor is further calculated as a quantitative measurement of uniaxial texturing. While the phase field modeling allows direct comparison between simulated grain structures and experimental microscopy observations, the computational diffraction allows convenient correlation between computer simulation and experimental X-ray diffraction characterization. The latter feature is especially desirable, since microscopy experiments normally require more efforts than X-ray diffraction, and diffraction is usually the preferred choice for material characterization.IntroductionThe properties of individual grains in polycrystals are generally anisotropic, while untextured polycrystalline materials with random grain orientations exhibit isotropic macroscopic properties that are independent of directions. In order to achieve anisotropic response in polycrystals, crystallographic texturing of grains is required [1]. Texture refers to the collective distribution of grain orientations towards preferred orientation in a polycrystal. To develop texture, special processing routes are needed, such as templated grain growth (TGG) for uniaxial texture [2]. TGG has been shown to provide uniaxial texture in wide variety of materials. For example, [001]-textured ferroelectric polycrystalline ceramics have been fabricated by TGG process, which exhibit enhanced piezoelectric properties [3]. Such highly textured polycrystalline materials offer better cost-performance ratio than single crystals. Thus, texture development in polycrystals is of technological importance for material applications.In this computational work, grain texture development in polycrystals during TGG process is studied. Grain structure evolution is simulated by phase field model, X-ray diffraction peak intensities for the evolving grain structures are computed, and Lotgering factor is calculated to quantitatively measure the development of uniaxial texturing. The phase field modeling allows direct comparison between simulated grain structures and experimental microscopy observations using imaging techniques such as scanning electron microscopy or optical microscopy. The computational diffraction allows convenient correlation between computer simulation and experimental X-ray diffraction characterization. The latter feature is especially desirable, because microscopy experiments normally require more efforts than X-ray diffraction, thus diffraction is usually the preferred choice for material characterization."

Jan 1, 2014

By Fumito Tanaka

The Mitsubishi process is the sole pyrometallurgical process for the continuous production of blister copper from copper concentrates and has been successfully operated around the world. The development of calcium ferrite slag (CaO-FeOx-Cu20), the so-called "C-slag", has enabled continuous converting from matte to blister copper in the commercial scale operations. Commercial interests in the slag led to many papers over the CaO-FeOx slag. However, CU2O- bearing slag has not been studied well due to experimental difficulties. The authors have quantified the thermodynamic properties ofthe CaO-FeOx-Cu2O system. The results have been utilized to analyze various issues related to the converting furnace, such as the magnetite precipitation from the slag or from blister copper and to develop better controlling criteria for the continuous converting operation.

Jan 1, 2003

By Cheng Yan, Yugang Li, Qian Wang, Lizhi Zhang

In continuous casting process, mold powder has lots of metallurgical effects, such as covering the molten steel to prevent liquid steel from oxidation by air, preserving heat for top layer liquid steel, lubricating initial shell and so on. However, mold powder also can deteriorate the quality of final products obviously after the entrapment of mold powder in steel. In the present work, based on the similarity theory the effect of technological parameters on mold powder entrainment was investigated by water model. Experiment was carried out in the water mold using oil and water to simulate slag and steel, respectively. The results showed that increasing casting speed increased the water-oil interfacial fluctuation and entrainment frequency; viscosity of oil also had a great impact on the interface fluctuation and entrainment; water-oil interfacial tension effect the entrainment while not changing the interfacial fluctuation; submergence depth had little impact on entrainment and interfacial fluctuation.

Jan 1, 2015

By A. N. Aposhian

The electronics industry generates tin/lead bearing by-products that can be recycled for their metal value. This paper will cover the processes used to recycle these tin/lead bearing byproducts from the plating, circuit-board fabrication and assembly industries. Though these processes are well known to the companies who do the recycling, few outside the industry including the generators of the by-products, understand the processes or needs of the industry. This paper will give a broad overview of these processes, and describe the services provided by this industry. The paper will also touch upon the future of the recycling industry, including the legislative and environmental push for the elimination of lead from electronics.

Jan 1, 2000

By O. Norman Lotter

There are many scales of innovation in the pursuit of concentrator performance improvement, including paradigm change, inventive change and incremental change. All are important, but the last is low risk, low cost and has a relatively high probability of success, given the right metallurgical skills. Seeking continuous improvement is also essential to ensure that performance does not decline over time due to ore type changes, personnel changes, equipment wear and other factors. When properly implemented, these small gains offer a very high rate of return for the project cost because they are made from marginal, not total, operating costs of the plant. To be effective this approach requires plant trials that use designed structure and appropriate statistics to test the observed differences arising from the old and new process treatments, be they a change in flotation reagent, in grind, pulp density, etc. However the pursuit of small but financially significant performance gains is often regarded as fruitless because of the range of variance in plant data, and the consequent difficulty of ‘proving’ that a benefit has been achieved. Opportunity for improvement is thus sometimes relegated to the realm of the impossible, or at best, treated with skepticism. Operations managers prefer to look for the larger gains, which are easier to demonstrate and prove. Unfortunately, these are seldom to be found; rather, a large gain can be more easily made by executing a series of small recovery improvements that are together equivalent to the ephemeral single large gain. In this paper we advocate a policy of continuing improvement driven by rigorous performance testing protocols and a formal ‘risk analysis’ approach to judging the efficacy of changes implemented in the plant. Following these simple procedures allows rational decisions to be made on the basis of quantifying risk and reward. In particular we consider the choice of hurdle rate for decision-making which best balances risk and reward. It is shown through case studies from actual industrial practice that this approach is practical and delivers significant financial value to the operation.

By Malti Goel

"Ferrous and Non-ferrous industry in India is undergoing a transition to meet the growing demand and a new thrust to Research & Development (R&D) is mounting. On one hand, to meet the target laid by the policy in the Iron and Steel sector of 110 million tones production by 2020; on the other, innovations taking place in light metal production technology; both have necessitated greater attention to development of industrial ecological framework. Industrial ecology provides a number of new challenges as well as opportunities for the industry. The development and growth in a particular industry should have a trend towards reduced energy consumption, reduced resource consumption, thereby reducing the cost of production. Technology management strategies will have a key role in achievement of these targets. The paper describes recent developments in technology management, importance of R&D and case studies on adoption of energy efficient & CO2 reduction technologies in metal industry in India. In the end suggestions for future are made.IntroductionInternational Energy Agency [1] has assessed that nearly one third of the World’s energy consumption and 36% of CO2 emissions are attributed to manufacturing industries. In case of ferrous and non-ferrous metals, the resource equality and product quality finally determine the energy share across the countries. In the overall, Iron & Steel industry accounts for about 19% of total industrial energy used. The saving potential for non-ferrous metals is estimated to be anywhere between 13 to 25 % of the energy consumed depending on the level of resource quality. The projections are that energy consumption worldwide in Industry sector would increase 1.8% per annum up to 2030 on average, and up to 2.5% in developing countries."

Jan 1, 2008

By Moto Goto

Today, Pierce-Smith converters, coupled together with various types of smelting units, are used in most of the world's smelters. However, due to the "batch" processing nature, and problems associated with fugitive emissions during the transfer of melt and blowing stages, this arrangement will unlikely be adopted in future smelters. Modern day alternative processes include the Mitsubishi Process, Outokumpu Flash Smelting and Flash Converting Process, the Noranda Process, and the Ausmelt Process, but only the Mitsubishi Process is a "truly continuous" smelting and converting operation, producing a constant flow of blister without tapping, and is economically proven by long term commercial operations. This paper reviews recent advances in modern continuous converting technologies, with a special section devoted to operation of the "first standalone Mitsubishi C-furnace" coupled together with a Noranda Reactor, at Port Kembla Copper Pty. Ltd. in Australia.

Jan 1, 2003

By Robert Matusewicz

Ausmelt Technology has been applied to the recycling of spent pot liner (SPL) generated from primary alnminum production. The process is centered on the Ausmelt furnace, in which the SPL is converted under high temperature, oxidizing conditions to an HF containing gas stream and inert slag. fluorine is recovered from the SPL as HF gas and is concentrated and used to manufacture AIF) for recycle to the aluminum smelters. Approximately 87% of the fluorine can be recovered and converted to AIF), with the remainder being effectively tied up in the by product slag. Cost projections show that the recycling process will be competitive with other processes for SPL. The production and recycling of AIF) provides available credit that significantly offsets the operating cost of the facility. Ausmelt Technology for recycling of SPL is currently being marketed in North America by Ausmelt Technology Corporation in Denver, Colorado, and in the rest of the world by Ausmelt Limited of Dandenong, Australia.

Jan 1, 1996

By Bin Xu, Qian Li, Yong-bin Yang, Xiao-liang Liu, Tao Jiang, Yan Zhang

Some high sulfur and arsenic-bearing gold concentrate has a gold leaching rate less than 80% by oxidation roasting-pickling-cyanidation process. The characteristics and intensification of gold leaching were studied systemically. By combining chemical composition and phase analysis, the low gold leaching rate was found to lie in the capsulation of gold by iron-containing phases including iron oxides, arsenopyrite and pyrite. 96.66% of gold in the industrial leaching residue was capsulated and 95.88% of the capsulated turned out to be in the iron-containing phases. The results of laboratory pickling-cyanidation experiments on the calcine and industrial leaching residue presented further demonstration for the fact that gold capsulated in the iron-containing phases was hard to be leached. However, the gold cyanide leaching rate of calcine could be raised over 95% by a reduction roasting-pickling pretreatment which played such a significant role in exposing the capsulated gold that gold leaching was intensified remarkably.

Jan 1, 2015