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By Akira Nishikawa

During the twentieth century, the copper smelting industry achieved dramatic expansion corresponding to the vast growth of global economy. This was largely due to innovations in pyro-metallurgical processes, such as autogenous smelting and continuous smelting and converting technologies. However, as copper production capacity increased, its impact on the environment also could not be ignored, and thus with increasing global environmental awareness, many smelting operations either had to renew or rebuild their facilities. In addition to these changes, in places like Japan and Europe, with scarce primary resources, the treatment and recovery of metals from a variety of items such as car shredder dust, used electrical appliances and electronic devices, on top of scraps traditionally treated, is having a profound effect on the reduction of waste and the preservation of primary resources. Thus compared to the days when copper smelting focused on the environmental control in order to break with "Smoke Stack Industry", copper smelting today is making an important contribution to the sustainable development of human society.

Jan 1, 2003

By C. Sui

A common objective in many Cu/Zn concentrators is to reduce the loss of Zn to the Cu-concentrate. One suspected source of the problem is accidental activation of sphalerite by heavy metal ions such as lead. One method of quantifying surface metal ion concentration is extraction with ethylene-diamine-tetra-acetate (EDTA). This was used to survey Cu-rougher flotation at three Cu/Zn concentrators: Les Mines Selbaie, Falconbridge's Kidd Creek division, and Hudson Bay Mining and Smelting Although all have less than 0.2% galena in the ore, Pb ions proved an abundant extractable metal. From a laboratory study a model of surface coverage of lead species generated by an ore was combined with an estimate of surface concentration of lead required to activate sphalerite to explore the possibility of accidental activation. Ores with Pb-grade as low as 0.1% can produce sufficient Pb to be a potential problem.

Jan 1, 1999

By Brady Butler

Many high capacity metal hydrides exhibit a high degree of stability in the hydrogenated state. This stability leads to a number of significant design problems with regard to the low temperature kinetics and thermodynamics of dehydrogenation. Nanometric metal hydride materials provide a promising route for increasing the reaction kinetics while altering the thermodynamic stability of the material. The use of nanometric metal hydride materials for hydrogen storage has largely been absent because of the difficulties associated with the synthesis of these materials. In this paper, research results on the synthesis of lithium based metal hydrides by vapor phase reactions are presented. The lithium based compounds that have been made in our lab include nanosized powders of metallic Li, Li₃N, LiNH₂ and LiH. The vapor phase process has also been used to custom engineer Li-based materials with other alloying elements or doping elements. The dependence of the characteristics of these materials on synthesis process parameters is studied. The effects of nanoscaled particle sizes on the kinetics of dehydrogenation and hydrogenation reactions are also explored.

Jan 1, 2006

By Neeraj Saxena, Madhu Huggahalli, Jerry Bednarski, Ken Grieshaber, David Stoffel

"The use of oxy-fuel burners in secondary aluminum melting applications offers several advantages over air-fuel burners including reduced fuel consumption, faster charge to tap times and lower NOx emissions. Their successful, safe and economical use in a furnace depends on several factors and considerations such as burner and flue placement, metal circulation, charge practices and the type of refractory used in the furnace.These factors required in the successful conversion of furnaces from air-fuel to oxy-fuel based burners are discussed in this paper. Critical parameters are identified and examined using computational fluid dynamics (CFD) simulations. Parameters are estimated via laboratory testing and validated through trials performed at commercial installations. Guidelines and a simplified approach to estimate a priori the economic impact of converting from air-fuel to oxy-fuel are presentedThe final products of this research are simplified and validated tools for modeling aluminum furnaces. These include improved heat and energy balance models and parameterized CFD solutions which provide rapid customization to individual furnace configurations. These tools provide field engineers with immediate and accurate predictions of performance, allowing for repeated precise scenario analyses."

Jan 1, 2001

By Yong Hack Lee

Nonferrous smelting processes have been through a rapid transformation since the beginning of 1980. The copper smelting technology has changed from the conventional Blast Furnace process to the Flash Smelting and MIB process. In the field of lead smelting, the technology has changed from the Blast Furnace Smelting to the Direct Smelting such as QSL and KIVCET. In 1992, Onsan Refinery successfully commissioned Direct Smelting QSL technology for lead. The QSL could produce more than 160,000 ton per year of lead bullion from lead concentrate and various residues. Moreover, since the year 2000, the TSL (Top Submerged Lance) Technology utilizing the same Direct Smelting process has been successfully commissioned to treat lead concentrate as well as lead sulfate residue produced from a hydrometallurgical zinc plant. This paper presents and compares the energy flows of lead smelting processes such as a conventional process and the Direct Smelting Processes plotted on the Pb-O-S phase diagram. The oxygen potential diagram suggests how to control the oxygen potential in the furnace. Also, it describes the recent operational experience in the TSL plant of Onsan Refinery with necessary mass balance of key elements.

Jan 1, 2003

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 Y. Moriya, Y. Sadayoshi, Y. Nonogaki, Y. Takeda

"Preparation and growth processes of CaF2 on Si(111) and of . InxGa1-x,As islands on CaF2 by molecular beam epitaxy (MBE) are described. It was found that first of all the Si(111) surface treatment process to obtain the 7x7 reconstructed structure was necessary to ensure the cleanness of the surface and to grow a flat and high quality CaF2 on it. Growth of InxGa11-x,As islands on CaF2 was tried by droplet heteroepitaxy using the same MBE reactor. In,GaxGa1-xAs islands were successfully grown epitaxially, and the size and density of the islands dependent on the In composition were investigated.IntroductionThough semiconductor/semiconductor heterostructures are widely used for many device applications, small band off-sets of the conduction bands and the valence bands restrict the utilization of the intra-subband transitions to far-infrared regions. With InAs as the quantum well and fluorides as the barrier layers, we can design three-electronic-level systems in the infrared region, which is the low loss transmission window of the silica optical fibers. To realize those structures, we have grown InxGa1-xAs islands on CaF2 thin films that were epitaxially formed on Si(111) substrates by molecular beam epitaxy. By the droplet heteroepitaxy that we invented, the InxGa1-xAs islands with height of -10 nm have been obtained successfully. Optimum processing to obtain atomically smooth surfaces of Si and CaF2 and high quality InxGa1-xAs islands is reported.ExperimentsMBEMachineCaF2 was grown on Si(111) and InxGa1-xAs islands were grown on CaF2 successively by MBE. The MBE machine consisted of a growth (or reactor) chamber and a loading chamber. The reactor chamber was equipped with Ga, In, As and Er metal source cells and CaF2 and BaF2 source cells. Cell materials were P-BN for Ga, In and As metals, and were graphite for CaF 2, BaF 2 and Er to avoid reaction with BN cells. The electron gun and screen were attached to the reactor to observe the RHEED pattern during the substrate surface treatment and the growth of CaF2 and InxGa1-xAs islands. The substrate manipulator was designed to heat up the Si substrate up to 1,200°C for the surface cleaning. The QMS was also equipped to analyze the residual gas species in the reactor chamber. The base pressure of the reactor chamber was 2-5x10-11 Torr, being pumped by ion pump and the liquid nitrogen shroud"

Jan 1, 2000

By John Pilling

The concept of microstructure, its evolution through materials processing and its effect on the properties of the material is, perhaps, the foundation upon which the science of materials is built. PHAUST, a computer aided learning program, attempts to provide instruction in establishing the relationships between phase diagrams, thermal processing and microstructure. Using phase diagrams derived from a database or created by the user, the evolution of microstructure during processing is quantified using the lever rule and/or the Scheil equation and tracked through a doubly linked list (a form of binary tree). Microstructures, in the form of full colour cartoons are then drawn using the quantitative and logical information contained within the linked list using bitmapped templates and logigal operators such as NOT. AND, OR and XOR, giving the student a view of the structure as it would be seen under the optical microscope. The software provides complete diagnostics of student answers, locates errors and misconceptions as well as providing tutoring towards the correct solution method and answer.

Jan 1, 1991

By R. R. Beebe

"Laboratory and pilot-scale tests are almost invariably required before metallurgical development can proceed. Difficulties with sampling, as well as with classical chemical and physical scaleups, are normally anticipated and relatively well-understood, but more subjective factors also come into play, including misunderstandings of the operating scheme chosen, wrong ""lessons"" learned from similar operations, failures to handle data appropriately, and even arbitrary intervention by management. The paper examines some of these subjective factors and suggests ways to guard against them. Several anecdotal case studies are used as examples, including when and where to heap leach or to mill specific types of gold ore.When the Romans first exploited the gold-rich gossans at Rio Tinto, they were guided by analyses and tests that delineated the ore deposits, identified the richer portions, and measured the gold recoveries achieved. There is little evidence, however, to suggest that test data were used to develop improved methods of metallurgical extraction. Indeed, it is likely that ores too difficult to treat were simply passed by, at least until improvements in full-scale operations could deal with them. For example, it is not difficult to imagine that an early metallurgist might test a tin ore by placing some in a fire; a smallscale emulation of the method actually used in practice."

Jan 1, 1997

By David C. Lynch

FeCl3 particulate of 10 to 100 um in diameter was reacted with radicals produced in an oxygen plasma at pressures between 1 to 20 Torr. The particulate, in a fluidized bed, was positioned above the plasma to avoid over heating the oxide product which is known to lead to crust and clinker formation[ 1 ]. Reaction between the iron chloride and the gas phase occurred at temperatures between 66 and 226 °C. Oxygen radicals react with the surface material to a depth of approximately 2.5 4m. Surface material, analyzed with a x-ray technique, indicates that the maximum amount of FeCl3 reacted on a weight basis was found to be approximately 67%. More typically, 40 to 50 wt% of the chloride was reacted within 30 minutes to 1 hour.

Jan 1, 1996

By Yasuhiro Konishi, Yoshiyuki Noda

"This paper describes a new processing of rare-earth oxide precursor, in which rare-earth carbonate powders are precipitated directly from emulsions of rare-earth loaded carboxylate solutions, using CO2 gas and water. This synthetic route of rare earth carbonate is a combined process of the stripping and precipitation stages in a conventional solvent extraction. Using this technique, lanthanum carbonate and yttrium carbonate were prepared at temperatures of 10 to 80°C and CO2 pressures of 0.1 to 3.0 MPa for 120 min. The rates of carbonate precipitation in a batch autoclave were sensitive to processing parameters such as CO2 pressure, temperature, and organic-phase composition. The particle size distributions of the carbonate powders were markedly dependent on temperature and C02 pressure.IntroductionSolvent extraction is the most appropriate commercial technology for separation and purification of rare earths. In typical commercial processes, the rare earths are stripped from loaded solvent extractants using aqueous solutions of mineral acid. After adjusting the pH of the aqueous strip solution, the rare earths are precipitated as insoluble powders of oxalates or carbonates, from which oxides can be produced by calcination. Such conventional processing can be simplified when the stripping and precipitation stages are combined by emulsifying rare-earth loaded solvent extractant with aqueous oxalic acid solution. It is likely that the single-stage precipitation stripping results in a marked decline in the consumed amounts of precipitating and neutralizing agents, thereby saving on both running and capital costs.Yoon and Doyle1) first demonstrated that oxalate powders of lanthanum and yttrium are directly precipitated from rare-earth loaded carboxylic acid solvent extractant when contacted with aqueous oxalic acid solution at ambient temperature and atmospheric pressure. Yttrium oxalate pow4ers were also prepared by precipitation stripping of di-(2 ethylhexyl) phosphoric acid. (D2EHPA) extractant using oxalic acid-hydrochloric acid solutions. 2) Moreover, neodymium oxalates were directly precipitated from organic solutions of tertiary aliphatic monocarboxylic acid and 2-ethylhexyl phosphonic acid mono-2- ethylhexyl ester using aqueous oxalic acid solutions, and powder characteristics of the resulting oxalates were compared with those of powders by the conventional solvent extraction routes. 3 • 4) Recently, attention has been directed towards the influence of processing parameters on the particle size distributions of yttrium oxalate precipitates. 5)"

Jan 1, 2000

By Renxing Li, Yongyong Gong, Yufeng Cheng, Zhenxing Yin, Xin Cao, Qijie Zhai

"This paper investigated the refinement effect of pulse magneto-oscillation (PMO) on the solidification structures of medium carbon steel S45C in metal mould. The induction coil was positioned at the middle of ingot. The results showed that solidification structure of the treated ingots was remarkably modified with a transformation from well-developed dendritic structures to small dendritic structures or globular structures compared to the untreated ingot. The area fraction of modified microstructure regions reached more than 80 percent. A further experimental investigation had been done to understand the influence of refinement effect on the solidification structure under different mould size. Theoretical analysis demonstrated that the mechanism for the refinement of solidification structure was that PMO promoted nucleation near the mould walls and changed the interface temperature gradient and concentration gradient in liquid, eventually leading to a transition from the columnar crystals to the equiaxed crystals.IntroductionIn recent two decades, the electromagnetic processing of materials (EPM) has been widely used in many fields such as ironmaking, steelmaking, and solidification processing [1-6], where EPM can control melt flow, modify melt shape, reduce macro-segregation and refine microstructure. Pulse magneto-oscillation [7-9] (PMO), as a novel technique of EPM, has a remarkable effect on grain refinement and high potentiality to be used in industrial production. Compared with ultrasound refinement technique, PMO can be easily employed to metal solidification processing for long time in no contact with hot metal liquid by using a water-cooled coil. Another important advantage is that PMO needs smaller energy compared to pulsed magnetic field which needs a very high current to obtain a strong magnetic field to get a satisfactory effect. These advantages mentioned above are beneficial for industrial application, which make it potential to be widely used in future. Gong et al. [7] have studied the refinement effect of PMO on pure aluminum and find that PMO can significantly modify the solidification structure of pure aluminum. Li et al. [9] have reported the effect of temperature field on solidification structure under the influence of PMO. On the basis of these works, this paper has studied the effect of PMO on solidification process of medium carbon steel S45C in a metal mould, which can also provide some information for industrial application of this new technique."

Jan 1, 2012

By Akira Nishikawa

During the twentieth century the copper smelting industry achieved dramatic expansion corresponding to the vast growth of global economy. This was largely due to innovations in pyro-metallurgical processes, such as autogenous smelting and continuous smelting and converting technologies. However, as copper production capacity increased, its impact on the environment also could not be ignored, and thus with increasing global environmental awareness, many smelting operations either had to renew or rebuild their facilities. In addition to these changes, in places like Japan and Europe, with scarce primary resources, the treatment and recovery of metals from a variety of items such as car shredder dust, used electrical appliances and electronic devices, on top of scraps traditionally treated, is having a profound effect on the reduction of waste and the preservation of primary resources. Thus compared to the days when copper smelting focused on the environmental control in order to break with "Smoke Stack Industry", copper smelting today is making an important contribution to the sustainable development of human society.

Jan 1, 2003

By B. Boryczko, J. Norwisz, Jose Escobedo Bocardo, Z. Kolenda, A. Holda

"Classical thermodynamic analysis of any thermal and chemical process is usually based on the first law of thermodynamics. Such an approach is not sufficient when deeper understanding of the nature of each elementary process is required. The use of the first and second law of thermodynamics together is necessary to solve practical process more effectively. Enthalpy and exergy balances allow to enhance our understanding of thermal processes especially when cumulative consumption of energy and exergy is calculated. To ensure reliability of such an analysis the least squares method for adjustment of mass balances of principal chemical elements has been applied and described in detail. Numerical analysis has been carried out to compare two different processes of copper production – shaft furnace and flash smelting.IntroductionClassical thermodynamic analysis of any technological process is usually based on the First Law of Thermodynamics in the form of energy (enthalpy) balances. Such an approach is useful in engineering practice as it makes analysis easier in the global scale neglecting modeling of the elementary processes, allows calculation of the thermal efficiency and makes possible to control quality of the measurement results. Additionally, graphical presentation of the energy balance is simple in the form of Sankey diagram.In the case of aluminum electrolysis process, design of the new electrolyzer or its modernization is always based on the enthalpy balance.However, deeper thermodynamic analysis leads to the conclusion that such an approach is not sufficient. The First Law of Thermodynamics guarantees the exact equivalence of the various forms of energy (allowing all forms to be measured in the common unit such as joules) but it does not guarantee interconversibility. Thermal energy (heat) is in a peculiar and unique position, for whereas all other forms can be completely converted into thermal energy, the reverse process id impossible, only a portion of the heat can be converted into mechanical energy. Explanation comes from application of exergy balances. As we know exergy expresses the amount of mechanical work necessary to produce a material in its specified state from components common in the natural environment, in a reversible way, heat being exchanged only with environment [1]. Consumption of exergy connected with the fabrication of some considered product appears not only in the plant manufacturing the product, but also in all plants delivering raw materials for the final production process"

Jan 1, 2008

By Bret Boster

Facilities at Amax Gold's Sleeper Mine process some 330 kt of high grade ore and 4100 kt of low grade ore annually to produce 6.8 t of gold and 7.8 t of silver. High grade ore is processed in a conventional milling facility employing gravity concentration, CIC and CIP unit operations for gold and silver recovery. Low grade ore is processed using heap leaching and carbon adsorption methods.. Presented are the evolution and descriptions of the Sleeper processing facilities and discussions of selected' operating results.

Jan 1, 1989

By Todd S. Fayram

The Gordonsville Operation of Pasminco US Inc. along with the Center for Advanced Mineral and Metallurgical Processing (CAMP) at Montana Tech studied, developed and implemented a pilot scale hydrometallurgical facility for the industrial recovery of germanium and gallium. This paper describes the joint testing and engineering program that culminated in this successful process.

Jan 1, 2003

By A. K. Kyllo, G. G. Richards

"The formation and control of accretions is an important aspect of process operation for gas injection. The nature of the accretion formed can have a considerable effect on a process, especially on the life of the lance or the refractories in the tuyere region. There are three basic shapes of accretion formed on tuyeres; pipes, hemispheres and hollow-cored hemispheres. However, there are wide variations within these shapes. Generally, the type of accretion formed will depend on the injector design, certain operating parameters and the physical properties of the bath materials. This paper seeks to collect the results of previous and current physical and mathematical modelling together with data gathered from operating furnaces, to obtain a better understanding of the effects of process design and operating variables on accretion formation.IntroductionAn important consideration in the design of a gas injection process is the possible freezing of the bath either around the tuyere or on the lance. With proper design, freezing may be controlled to provide protection of the lance or refractory, and to avoid blockage. Improper design may lead to tuyere blockage and significant refractory or lance erosion. In view of this, a good understanding of the heat transfer in the injection region is essential.While tuyere blockage has been a persistent problem since the inception of submerged gas injection processes, the problem of accretion formation was not studied in detail until the development of the shrouded tuyere by Savard and Lee. A number of studies relating to accretion formation have been carried out since then, but there is still little information available relating the nature of the accretion formed to the design of the injection system.The build up of materials on lances is a similar problem, and may also be either beneficial or detrimental, depending on circumstances. Unfortunately, there is even less information available regarding build up on lances than there is relating to tuyere accretions. While the form of build up on lances is generally a simple coating of the lance, accretions on tuyeres tend to be more complex. Tuyere accretions tend to occur in one of three basic forms: pipe, hemispherical and hollow-cored hemispherical (Figure 1). However, there appears to be a considerable variation within these forms."

Jan 1, 1996

By Juan B. Cabezas

"The favorable characteristics and workability of plastics as a replacement of wood, lead, stainless steel, asphalt and other materials are described. Various types of plastic have proven to be the most favorable choice for handling a variety of acidic, alkaline and organic solutions, as well as pulps, chemical wastes, slurries or tailings for impoundments. The material origin of various plastics, methods of manufacturing and specifications applied to leaching solutions are discussed, including availability and costs. Examples of select plastics are considered for use as alternatives of other materials under severe environmental requirements.IntroductionHydrometallurgical processes applied to gold recovery, as well as other metals, require the use of strong solutions of alkaline, acidic or organic nature, and may also include a variety of materials with extraneous characteristics and complications for handling in storage.The technology of leaching has been in use for more than 100 years, but the applications of leaching processes in metallurgy have become more commonly used in the last 15 years. Suitable materials for the construction of containers, launders, piping, and various accessories, to be used in the handling of leach solutions or slurries, have become a serious problem. Various metals such as brass, lead, stainless steel, etc., and non metallics including wood, clays, glass, rubber, ooncrete, tars or miscellaneous compounds have been tried in the past with serious limitations in workability and resistance to wear and corrosion. For example, the use of metallic, wooden or glass piping systems would require extraordinary shop maintenance to keep such systems in operation"

Jan 1, 1997

By W. G. Davenport

Chapter 6 examined autotherrnal smelting of pure chalcopyrite concentrate with 50 mass% O2-50 mass% N2 blast. It showed that production of 1500 K products with this blast requires: 181 kg of pure oxygen 337 kg of air per tonne, of concentrate. It also showed that the grade of matte produced with this blast is 58% Cu. This chapter re-examines autotherrnal smelting by asking: (A) WHAT COMPOSITION BLAST (MASS% 02 -MASS% N2), 298 K, WILL AUTOTHERMALL Y PRODUCE 65% Cu MATTE 1500 K FROM PURE CHALCOPYRITE CONCENTRATE? (B) HOW MUCH PURE OXYGEN AND AIR WILL BE NEEDED? These are important questions for flash? smelting because furnace operators usually want to send specific composition matte to converting. This chapter shows how a specified matte can be produced autotherrnally with 298 K oxygen-air blast. Later chapters show how it can be done with hot blast, hydrocarbon combustion, different concentrates etc.

Jan 1, 2001

By T. V. Jayaraman

Fe-Ga alloys, with compositions around 27.5 at % Ga, can be heat treated to obtain ? (ordered bcc), DO19 (ordered hexagonal), and L12 (ordered fcc) ordered structures. Our earlier work using polycrystalline samples had shown that magnetostriction is strongly influenced by ordering in this alloy. Here more detailed study of the correlation between ordering and magnetostriction using single crystals of Fe 27.5 at. % Ga alloys is reported. Single crystals of Fe 27.5 at % Ga were grown using Bridgman single crystal growth technique. X-ray and electron diffraction were used to study the ordering in this alloy. Magnetostriction measurements were carried out at no load conditions. Elastic constants were measured using Resonant Ultrasound Spectroscopy.

Jan 1, 2006