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By Milton Manrique

The thermal decomposition of zircon concentrates in a non-transferred arc thermal plasma flow reactor was investigated. The plasma torch was operated using argon-helium and argon-nitrogen mixtures as plasma gases. The effect of power, feed rate and zircon particle size was studied. Products were characterized by XRD, SEM, TEM and chemical analytical techniques. The average size of the product was in the submicron range. Free energy minimization plots were used to predict the behavior of the system under different operating conditions. A kinetic model to describe the different stages of the thermal decomposition process is proposed. The results of this investigation showed a significant segregation process where the zirconia-rich product is collected in the reactor while the silica-rich product is collected in the filter. TEM analysis indicated that silica vapor is condensed on the surface of the zirconia particles.

Jan 1, 1996

By K. Osseo-Asare

Third phase formation, the separation of a solvent extraction organic phase into two liquids, is generally attributed to the limited solubility of the extracted complexes in the hydrocarbon diluents. Much of the research on third phase fomiation, therefore, emphasizes experiments designed to establish the stoichiometry of the species responsible for the limited solubility. This work offers a different approach, based on the recognition that the solvent extraction third phase, in fact, corresponds to the middle phase in a microemulsion fluid system. Using the tri-n-butylphosphate (TBP)-diluent-water-electrolyte system as a model system, current concepts of microemulsion phase behavior are utilized to develop a general framework for interpreting and predicting the patterns of phase behavior in solvent extraction systems.

Jan 1, 1999

By Hong Yong Sohn, Miguel Olivas-Martinez

"Different approaches are used for calculating the ‘energy requirement’ of a process. The determination of energy requirement becomes confusing for a process in which a fuel is also a reactant. The key issue is which heat of chemical reaction should be included in the ‘energy requirement’ value. We will use the example of ironmaking processes to illustrate the problem. The different approaches essentially boil down to the question: does one include the combustion heat of the reductant used in the reduction reaction or just the heat of the reduction reaction? Depending on the viewpoint, either approach can be accepted; it is a matter of convention. There is a need, however, to select a standard approach because the absolute value of ‘energy requirement’ of a process depends on the choice. The energy requirement of a novel flash ironmaking process will be compared with that of an average blast furnace operation.IntroductionDifferent approaches are used for performing energy balance calculations and perhaps more significantly in presenting the ‘energy requirement’ of a process. The question becomes more involved for a process in which one or more reactants are also used to generate the process heat by combustion. Often the key issue is which heat of chemical reaction to include in presenting the ‘energy requirement’ of the process.It is worthwhile to note at the outset that the difference in energy requirements between different processes for converting similar raw materials to the same desired product is largely unaffected by the choice of chemical reactions to be included. However, the absolute value presented as the ‘energy requirement’ of a process can be different by a large amount depending on the approach. We use the example of ironmaking processes to illustrate the problem. In these processes, as currently practiced or under development, carbon and/or hydrocarbons (including hydrogen) are used as the fuel as well as the reactant for reducing the iron oxide mineral.The different approaches in this case essentially boil down to the following question: does one include the combustion heat of the reductant used in the reduction reaction or treat the reductant portion as just a reactant? Depending on the viewpoint, either approach can be considered acceptable. It is a matter of convention. There is a need, however, to select a standard approach because the absolute value of ‘energy requirement’ of an ironmaking process (e.g., the currently dominant blast furnace process) depends on such a choice. It is particularly important to clearly state the specific approach used when the energy requirement of ironmaking is compared with those of other industrial processes such as petrochemicals production."

Jan 1, 2014

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 Daguang Lu

The section of sintering and BF (blast furnace) is very important in iron-making process. In practice, the scheduling is so extensive that three faults unfavorable to continuous product will be easier to happen. This paper introduces the integration Petri Net and GA (genetic algorithm) as suitable tools for simulation and optimization of scheduling to section of sintering- BF under a certain hot iron or-der. The situation of the iron plant Chongqing Iron and Steel Company is researched in approach above mentioned. By analysis, the conclusion is drawn that scheduling with optimized values can maintain continuity of key operations , can satisfy order of hot iron in maximal degree and can keep the best stability of key storages.

Jan 1, 2009

By P. D. Lee

The effect of strontium on porosity formation in aluminum-silicon alloys is not well understood and there is no consensus upon the cause of the effects observed. This paper describes a series of experiments where the effect of adding strontium on pore formation was observed directly with combination of a traditional temperature gradient stage and real time micro-focus radiography. These in situ observations provide a new insight into the effect of strontium on the nucleation and growth kinetics of porosity. The addition of strontium was found to have a minor effect on the growth of the pores in the mushy zone. However, strontium appeared to alter the nucleation and stability of hydrogen bubbles within the melt. The interaction of strontium with titanium-boride grain refiners produced an even stronger change in the nucleation and stability of the bubbles formed.

Jan 1, 2002

By N. J. Themelis

In the last two decades, the Outokumpu flash smelting process has become the dominant new technology for copper smelting and has? also been applied to the smelting of other metal sulfides. The application of oxygen enrichment and improvements in concentrate burner and furnace design have resulted in ever increasing smelting rates per unit volume of the reaction shaft. This paper examines the. rate phenomena taking place in the reaction shaft of the Outokumpu furnace and compares information obtained from a mathematical model of heat and mass transfer rates to results obtained in pi1ot tests conducted at Pori, Finland, and to actual performance of a number of flash smelters around the world. 2?

Jan 1, 1985

By S. Seetharaman

The present paper presents. the concept of micro-models and illustrates the application of the same in the simulations metallurgical processes. Development of micromodels requires access to accurate thermodynamic, thermophysicaland kinetic information for the relevant systems with suitable models to extrapolate the data as functions of temperature and composition. Experimental measurements and modelling of the thermodynamic properties, sulphide capacities and viscosities of oxide melts carried out in the department are presented. The incorporation of these models in process models, with special reference to ladle refining of steel is illustrated. Typical example of micro-modelling of solid-gas reactions is also presented.

Jan 1, 1999

By D. M. Hausen

It has been demonstrated that microscopic techniques can be applied in a practical manner to the study of spodumene liberation in the processing of pegmatitic ores at the Kings Mountain spodumene plant, Kings Mountain, North Carolina. Spodumene and associated non-opaque gangue minerals are identified and quantified by microscopic point-counting of polished thin sections of heads, concentrates, middlings and tails fractions. Specially prepared polished thin sections? provide uniform thickness of particles for measurement of diagnostic optical properties and the alternate use of incident and transmitted light in distinguishing the various gangue and ore minerals. Spodumene is commonly associated and interlocked with quartz, albite, microcline and muscovite. Concentrate grade depends on the degree of spodumene liberation, which in turn depends on the crystal size and textural association of interlocked minerals. The liberation of spodumene can be measured as a function of screen size by means of microscopic point-count data. Microscopic data also provide useful metallurgical information about the nature of diluent minerals in spodumene concentrates, and the form of lithia losses in the tails. Lithium assays correlate closely with microscopic spodumene analyses in various flotation products from Foote Mineral's Kings Mountain plant, and confirm the applicability of quantitative optical microscopy to the study of liberation and recovery of spodumene from pegmatitic ores. A better understanding of recovery-grade relationships was developed as a result of quantitative microscopy studies.

Jan 1, 1981

By Giuseppe Bonifazi

Minerographic and petrochemical research was carried out on crude ore samples from the complex polymetallic Zn-Cu-Pb sulfide ores of , Sotiel in Huelva province west of Seville, Spain. A computerized image analysis system was used to define the structural and textural characteristics of the ore to obtain information on the degree of liberation of the different minerals (i.e. pyrite, sphalerite, galena, chalcopyrite). Techniques of digital multispectral image processing of reflected light microscopy images were used. Particular structures were identified by means of mineral associations and numerically quantified to obtain useful information for designing beneficiation processes.

Jan 1, 1991

By A. E. M. Warner

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

Jan 1, 2003

By Yi Tan, Kazuki Morita, Yaqiong Li

Molten Si-Al alloy, with the addition of Sn, was used for metallurgical grade Si purification by a low-temperature solidification method, with the aim of improving the recovery rate of Si. In this ternary melt, bulk Si was grown with a planar front by a directional solidification process under a well-controlled thermal gradient and growth rate conditions, thereby reducing the contamination of solvent metals. Effects of cooling rate, amount of Sn addition, and temperature gradient on the quality of bulk Si were determined. The criterion for constitutional supercooling for single-phase growth from multicomponent melts was employed to evaluate the growth process.

Jan 1, 2015

By Isrun Bohlinger

Resources recovery of brasses for semifinished products often results in the formation of hard spots impairing the quality of following abrasive and/or surface finishing processes. A short survey is given on the recycling processes, followed by the actual knowlegde of genesis, composition, and possibilities of avoidance of hard spots. Informations on genesis and composition of hard spots are completed by data from recent experiments.

Jan 1, 1998

By Milton Blander

A review of concepts and theories for predicting thermodynamic solution properties of multi- component high temperature liquid solutions is reviewed. During the last 50 years the ability to predict :such properties for molten salts, silicates and metals based on the generally known properties of the lower order (often binary) systems has been developed and shown to provide predictions which are quite useful in science and technology. There are many gaps in our understanding of these high temperature solutions, especially for metals, and considerably more work is needed.

Jan 1, 1996

By H. Shang

The materials science and metallurgical engineering communities have expended enonnous resources in developing high fidelity process models. Exploiting these Models for Predictive Optimization (MPO) and Control (MPC) is a new frontier in Materials Process Engineering that will lead to exceptional process perfonnance. This paper will begin with a short survey of the development of high quality process models available in the literature and a discussion of how these could be used to improve process operation. A summary of the current "state-of-the-art" in process automation technologies and the traditional framework in which these technologies are deployed will be presented. An illustration of the use of MPO in process design and operations will be presented for the continuous casting of steel. In addition, a simple run-out table simulation will be used to demonstrate the power of the MPC technique.

Jan 1, 2003

By A. Mezei

Samples of cobalt and bismuth concentrates produced from the NICO deposit in Northwest Territories were subjected to a comprehensive metallurgical testwork consisting of: pressure oxidation, ferric chloride leach and carbon in leach, to recover the cobalt, bismuth and gold, respectively. A specific testwork program was designed to allow for the optimization of process parameters under multiple restrictive criteria. The overall objective was to establish leaching sequences that could produce acceptable recoveries while generating environmentally disposable residues as well as solutions suitable for further processing. The recoveries for the leaching stage, under the optimum conditions, were 97% for cobalt and 95% for gold, in the case of the cobalt concentrate. The bismuth concentrate produced recoveries of 99% for bismuth, 99% for cobalt and 97% for gold, respectively

Jan 1, 1999

Carbon injection into metallurgical slag is important in electric arc furnace (EAF) steelmaking for foamy slag practices and in nonferrous slag cleaning operations. The current publication presents kinetic data for coal injection into EAF slag to understand the interaction between injected carbon and metallurgical slag. Coal particles were injected into EAF slag and the kinetics were followed by gas and slag analysis. The results were analyzed, in terms of fundamental rate equations for each possible reaction step, as a function of temperature and slag composition.

Jan 1, 2003

By Harvey Alter

National attention in, recycling focuses on municipal solid waste (MSW), even though only about 50'million tons or so of MSW can be recycled, including grass, leaves and other yard wastes. The scope and value of the recycling of industrial "wastes" is much greater. It is possible to account for some 240 million tons of material recycled at the industrial scale annually, which is likely a conservative estimate. Some of this recycling reduces what would otherwise be hazardous waste to 'comrnodities and non-hazardous residue. Global trade in recycled commodities is outlined, as well as the-effect of the Basel Convention on the Trans boundary Movement of Hazardous Wastes A recent Decision under the Convention can, diminish the trade; deny developing countries needed secondary raw materials, and put world markets in chaos. Current U.S. government policies and activities toward ratification of the Convention, and possible new regulation of industrial recycling activities, will be discussed. There are federal proposals that would regulate industrial recycling differently for on-site and off-site facilities and judge legitimate or "sham" recycling according to the concentration of so-called "toxics along for the ride."

Jan 1, 1995

By Sven Eck, Andreas Ludwig, Menghuai Wu

"Phase separation is a frequently occurring phenomenon during solidification accompanied by melt convection, sedimentation or, in the case of two unmixable liquids, a Marangoni driven motion. In order to describe these phase separation phenomena a two-phase volume-averaging model was employed for globular equiaxed solidification of binary alloys and decomposition and solidification of hypermonotectic alloys. The model considers nucleation and growth of equiaxed grains or second phase droplets, motion and sedimentation of grains or droplets, feeding flow and solute transport by diffusion and convection. It allows the prediction of macro segregations and the distributions of grain size or droplet size. Evaluations were made by comparing the numerical predictions with experimental results. For example it is shown that the numerically predicted grain size distribution in a plate casting (Al-4wt%Cu) agrees reasonably well with the experimental analyses.IntroductionModeling of metallurgical processes is a rapidly expanding field and the research activities in the last decades cover a wide range of areas including melt pre-treatment, solidification and subsequent manufacturing routes. Among those activities solidification stands in the central position, because the primary structure of the materials, and even many defects such as porosity, (macro or micro) segregation and inclusions form during solidification. Those primarily formed structures or defects once existing are difficult to be removed or modified by the subsequent material processing.Solidification is a multi-disciplinary field involving thermodynamics, fluid dynamics and solid mechanics, heat and mass transfer, and other disciplinesr1 -31• One of the most challenging problems in solidification modeling is the complex interactions between physical phenomena occurring on different length scales ranging from atomic rearrangement over single crystal-melt interactions to heat extraction, momentum and species transport at the system level. Modeling an industry process on atomic scale is umealistic, even on grain scale (e.g. phase field method) it would need another 40 years to be able to model the exact grain morphology in a casting space envelope of 10x10x10 cm3 [ 4]. Therefore, the realistic models for industry process are based on the solution of the macro transport equations (mass, momentum, enthalpy and species) on system scale. The microscopic phenomena such as thermodynamics, nucleation law, crystal growth kinetics and interactions at the liquid-solid interface are considered with simplified models, which are coupled with the macroscopic transport equations."

Jan 1, 2004

By I. Gaballah

The kinetics of oxychlorination of pure CI-2O3 with C12+02 gas mixtures is studied by ThermoGravimetric Analysis (TGA) in non and isothermal conditions up to 1000 °C. The reaction of Cr2O3 with C12+O2 chlorination gas mixtures starts at about 550 °C and the reaction product is CrO2Cl2. The oxychlorination rate of Cr2O3 is almost proportional to the chlorine partial pressure and to the fourth root of the oxygen partial pressure in the chlorinating gas mixtures. At 800 °C, the maximum chlorination rate is obtained using a gas mixture having a C12/O2 ratio equal to 4. The apparent activation energy of the oxychlorination reaction of Cr2O3 is 87 and 46 kJ/mol at temperatures lower and higher than 650 °C, respectively. By varying the chlorine and the oxygen partial pressures of the oxychlorinating gas mixtures at temperatures higher than 550 °C, it is possible to extract selectively the chromium chlorinated compounds from the chromium bearing materials. a. Laboratoire Environnemem et Minéralurgie, BP 40, 54501 Vandceuvre, France, b. École Nationale Supérieure de Géologie, Rue du Doyen Marcel Rouhault, 54501 Vandoeuvre Cedex, France, c. Centre National de la Recherche Scientifique, 3 rue Michel - Ange, 75794 Paris Cedex, France, d. Insritut National Polytechnigne do Lorraine, Rue de la Font de Haye. 54501 Vandceuvre Cedex, France.

Jan 1, 1997