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By M. I. Zinigrad

A model of an ideal associated solution is presented. This model takes into account the existence of complexes of various compositions, sizes and geometries and allows calculating thermodynamic properties and phase diagrams of binary alloys. The model has been used formerly to calculate thermodynamic parameters and the position of the liquidus line for binary eutectic systems and also those having a stable compound in the solid phase. In all the cases the model parameters were not adjusted rather estimated from melting temperatures of the components. The recent studies dealt with the influence of arbitrary-stoichiometry associates on the equilibrium thermodynamic properties of liquid alloys. The application of the model to eutectic systems and systems having an unlimited solubility in solid and liquid states close to liquidus has been considered. It was shown that if the difference in melting temperatures of the components was small, different types of fusibility diagrams were possible: eutectic diagrams, cigar-shaped diagrams or diagrams with upper or lower azeotropic points. Peritectic transformations could take place when the difference in melting temperatures of the components was large. The present work is devoted to calculation of phase diagrams and thermodynamic properties of binary systems on the basis of chrome.

Jan 1, 2006

The reported values of the standard reduction potentials of the Au(NH3)2+/Au(0) and Au(S2O3)23-/Au(0) couples are reviewed to emphasise the experimental difficulties associated with the measurement of reliable values for these quantities. The standard reduction potential for Ag(I)/Ag(0) in ammonia and thiosulphate solutions measured at ionic strength 0.1 and 25oCis used to predict the following relevant stability constants () for gold complexes based on the linear free energy correlations: Au(NH3)2+2 = 1013, Au(S2O3)23-2 = 1024 and Au(NH3)43+4 = 1033. The equilibrium constant ( 10-11) for the reaction Au(S2O3)23- + 2NH3 = Au(NH3)2+ + 2S2O32- based on these stability constants is in reasonable agreement with the measured value (10-9) based on potentiometric and spectroscopic data when excess ammonia was added to a solution of Na3Au(S2O3)2. This also indicates that the stability constant of Au(NH3)2+ is 9 to11 orders of magnitude less than that of Au(S2O3)23-. Relevant species distribution and Eh-pH diagrams based on the revised data are presented.

Jan 1, 2003

By A. G. Guézennec

Electric Arc Furnace (EAF) steelmaking co-produces amounts of dust (15 to 25 kg per ton of steel), which require to be collected and stored in specific landfills. The collection, handling, and possible beneficiation of EAF dust depend on its composition and morphology. We first studied theoretically the chemical evolution of dust particles along the fume extraction system, from the furnace down to the filters, using thermodynamic calculations of the Fe-Zn-O system. We show how it would be possible to favor zincite formation in dust and therefore increase further zinc recovery. Then, we developed a new morphological model, based on population balances, for predicting the granulometric evolution of dust particles as a result of agglomeration and sintering in the fume extraction ducts. The contribution of the various mechanisms (Brownian, turbulent, and sedimentary agglomeration; thermophoretic deposition; coalescence and sintering) is assessed. The influence of the exhausting conditions on dust granulometry is detailed. For the extraction system studied, intense agglomeration of the sub-micronic particles and complete coalescence take place inside the furnace; micronic particles then undergo little evolution from the elbow to the water-jacket, whereas big agglomerates are formed downstream. These results are in good agreement with dust particle observations.

Jan 1, 2006

By Damien Wagner

To reduce the emission of greenhouse gases by the steel industry, particularly for ironmaking, the production of DRI (Direct Reduced Iron) using hydrogen as the reducing gas instead of carbon monoxide is being considered. In this context, the reduction of pure hematite by hydrogen was studied at the laboratory scale, varying the experimental conditions and observing the rate and the course of the reaction. All the reduction experiments were performed in a thermobalance and supplementary characterization methods were used like scanning and transmission electron microscopy, X-ray diffraction, and Mössbauer spectrometry. The influence of rising temperature in the range 550-900°C is to accelerate the reaction; no slowing down was observed, contrary to some literature conclusions. A series of experiments consisted in interrupting the runs before complete conversion, thus enabling the characterization of partially reduced samples. Interpretation confirms the occurrence of three successive and rather separate reduction steps, through magnetite and wustite to iron, and illustrates a clear structural evolution of the samples. Finally, the influence of the sample type was revealed comparing a regular powder, a nanopowder and a sintered sample. The regular powder proved to be the most reactive despite its larger grain size, due to a more porous final structure.

Jan 1, 2006

By Mark Kruzynski, Srinivas Garimella, James T. Wiswall

"A flue gas recirculation (FGR) system for a combustion fired aluminum melting furnace is experimentally investigated. The FGR system flows combustion air in a turbulent jet within the flue gas stream, and the turbulent jet flow is collected in a tube at a distance from the jet exit. Entrainment of the flue gases as well as heat transfer between the flue gases and the jet occurs over the length of the exposed jet. Heat transfer between the flue gases and the jet, and the amount of flue gas entrained into the jet (derived from temperature, flow rate and oxygen fraction measurements) were measured as a function of nozzle exit velocity and the distance between the nozzle exit and collection tube. In addition to flue gas entrainment, a fuel savings of up to 7%, due to heat transfer over the length of the jet, was projected from the measurements obtained.IntroductionFlue gas recirculation can be applied to aluminum melting furnaces to control combustion temperature. When coupled with a device to improve furnace efficiency by recovering heat from the furnace exhaust, flue gas recirculation provides a control technique that is integral to achieving the goals of reducing fuel consumption, increasing product yield, increasing the longevity of infrastructure, and reducing pollutant emissions. In particular, combustion temperature control can help reduce reactivity of the products of combustion with the molten metal surface and furnace refractory materials. Combustion temperature control can also help improve the life of heat exchangers used to recover energy lost to the environment in the flue gases, and reduce NOx formation in the combustion process. Flue gas recirculation can also dilute oxygen used in oxy-fuel combustion to reduce reactivity.Flue gas recirculation has been used since the 1970s to control flame temperatures in the automotive industry [1-3] and has successfully reduced NOx emissions. Many different flue gas recirculation approaches for high temperature melting such as melting aluminum and glass have been patented since the 1980s [4-12]. There has also been academic interest to determine the fundamental performance characteristics of flue gas recirculation in high temperature furnaces and in combustion [13-15]."

Jan 1, 2014

By R. M. Moon

Neutron scattering has played a crucial role in advancing our understanding of rare-earth materials. It has provided a detailed description of the rich array of exotic magnetic structures; it has confirmed the accuracy of theoretical wave functions for the 4f electrons; and it has provided fundamental data on the collective magnetic excitations in these materials. The fundamental property of the neutron which has been exploited in this work is the magnetic interaction which exists between the magnetic moment of the neutron and atomic magnetic moments on individual rare-earth atoms. This interaction produces scattering of neutrons in a manner closely analogous to the scattering of X rays by atomic charge distributions. In a material exhibiting long-range magnetic order, Bragg diffraction peaks will appear at scattering angles determined by the periodicity of the magnetic structure. The Bragg intensities are determined by the magnitude and relative directions of the atomic moments. The rare-earth metals and alloys are characterized by sinusoidal modulation of magnetic moment components which can be combined in various ways to produce a variety of magnetic structures. The periodicity of these modulations is frequently not related simply to the underlying periodicity of the chemical structure. The major features of these structures are explained by the combined, and sometimes competing, exchange and crystal-field interactions. At a more fundamental level, neutron diffraction also gives information on the spatial distribution of a magnetic moment in a rare-earth atom. This moment comes from the 4f electron shell, and accurate measurements of the neutron scattering amplitudes have been used to check the accuracy of atomic wave function calculations for the 4f electrons. It was found that relativistic Dirac-Fock calculations are in excellent agreement with the experimental results. Collective excitations of ordered magnetic systems are described in terms of spin waves, which are sinusoidal modulations in space and time of the direction of the ordered moments. Inelastic neutron scattering is used to measure the energy and wave length of these collective excitations. Analysis of these data gives direct information on the interatomic interactions responsible for the magnetib properties of these materials.

Jan 1, 1992

By Shuo Wang, Yu Wang, Bing Xie, Rui Tang, Hong-Yi Li, Kun Wen

"During present converter vanadium extraction process, phosphorus could not be removed from hot metal due to absence of CaO in slag though it is an efficient way for vanadium extraction. In order to improve the phosphorus remove and produce CaO-containing vanadium slag, which could be directly used in subsequent roasting process, during the converter vanadium extraction process, lime dissolution in FeOx-Si02-V203-Ti02 slag was investigated by using a rotating cylinder technique and the slag-lime interface was characterized by SEM/EDS. Results showed that changes in the slag chemistry and phase compositions during the lime dissolution process were similar to that in CaO-Si02-FeOx based slag during the BOF process. The V and Ti in the slag were expected to diffuse into the lattice of2CaO·Si02 solid solution, which formed a rather thinner layer in thickness at the slag-lime interface than that in BOF process, leading to improvement of lime dissolution in the slag.IntroductionVanadium is important material that widely applied in industries. The traditional technique to extract vanadium was to leach vanadium after sodium salt roasting. However, the sodium salt roasting process has several problems including lower yielding rate[!] and environmental pollution[2]. Therefore, the more environment-friendly technique of calcium roasting[3-4] was proposed. In order to increase roasting efficiency of vanadium slag, it is essential to study the dissolution/reaction mechanism between lime and vanadium slag. Many investigations about the dissolution reaction of lime in molten slag have been carried out from the standpoints of rapid slagging to De-Pin steelmaking process[5-6]. However, their studies were focused on BOF slag and the reaction mechanism between solid lime and slag containing vanadium has not been reported yet. In present work, the dissolution process was studied with rotating cylinder technique and the reaction interfaces were observed and analyzed by SEM/EDS to elucidate the dissolution mechanism of lime in vanadium slag. This work was supported by National Natural Science Foundation of China No. 51090382."

Jan 1, 2013

By Mingming Zhang

"Three samples received from the EAF shop have been characterized by chemical, X-ray diffraction (XRD), optical microscopy (OM) and scanning electron microscopy (SEM) methods. The objective of this characterization work is to investigate the occurrence of nickel, copper, zinc, sulfur and phosphorus in these samples and identity their origin and associations with iron minerals in the concentrate samples that are from mines.The samples were identified as Mineral, Pellet, and HRD. The latter is the DR! product. All three samples were received as fine powders. The results indicate that, in the mineral sample, magnetite is the major iron oxide mineral with hematite as a second phase based on the OM and XRD studies. Pyrite [FeS2], chalcopyrite [CuFeS2] and bravoite [(Fe,Ni)S2] are major sulfide minerals. Trace amounts of apatite [Ca5(P04)3(F,Cl,OH)], wardite [Na4CaA112(P04)8(OH)8 6H20], giniite [Fe5(P04)4(OH)3 2H20] and vivianite [Fe3(p04)2 8H20] were identified by SEM and XRD. Microscopic studies also indicated that most of the sulfide grains in the mineral sample are present either as liberated fine particles (about 10 microns) or as inclusions within the magnetite and hematite grains. XRD studies revealed magnetite as the major mineral with subordinate amounts of hematite and pyrite confirming the microscopic findings. Copper, nickel, and zinc are mainly present as chalcopyrite, bravoite, and franklinite [(Zn,Mn,Fe)(Fe,Mn)204] in trace amount in the mineral samples, respectively. Impurities carry over to the Pellet and HRD samples.Chemical analyses of the three iron-bearing samples indicate that sulfur and phosphorus in the Pellet sample exceeded the specification. Since liberated pyrite and chalcopyrite particles were observed both in mineral and pellet samples, magnetic and flotation processing routes for this ore should be effective for sulfide removal but at the cost of iron losses. The high phosphorus content of all three samples indicates that there are phosphates which are difficult to remove by the current concentrating process (magnetic separation and flotation)"

Jan 1, 2012

By Jean Igor Margem, Lucas Barbosa de Souza Martins, Frederico Muylaert Margem, Noan Tonini SImonassi, Sérgio Neves Monteiro, Rômulo Leite Loiola

"Fibers of giant bamboo (Dendrocalmus Giganteus) are amongst the strongest lignocellulosic fibers. Although studies have been already performed, limited information exists on the mechanical properties of polymeric composites reinforced with continuous and aligned giant bamboo fibers. This work evaluates the tensile strength of this type of composite. Standard tensile specimens were fabricated with up to 30% of fibers aligned along the specimen's length. The fibers were press molded with a commercial epoxy resin mixed with a hardener and cured for 24 hours at room temperature. The specimens were tested in an Instron machine and the fracture surface analyzed by scanning electron microscopy. The tensile strength increased significantly with the amount of giant bamboo fiber reinforcing the composite. This performance can be associated with the difficult of rupture imposed by the fibers as well as with the type of cracks resulting from the bamboo fiber/epoxy matrix interaction, which prevents rupture to occur.IntroductionDue to growing concern about the ambient impacts from industrial activities, our society is ever more using environmentally friendly materials. In this regard, cellulose-based natural fibers, known as lignocellulosic fibers, become a promising solution. Nowadays, they are being considered as a substitute for synthetic fibers, such as glass fiber, used by the industry on a large scale [1-5]. The application of these natural fibers is also motivated by many advantages like good toughness and less wear of equipment used in the processing of composites. In addition, such composites are environmentally friendly because they are renewable, biodegradable and neutral with respect to C02 emissions, the main responsible for global warming and climate changes. [3,5,6].Lignocellulosic fibers also have some disadvantages in relation to synthetic fibers such as the difficulty of coupling with polymer matrices, due to the hydrophilic character of fiber and the hydrophobic nature of the matrix, as well as dimensional heterogeneity [ 4,5]. This last one is characteristic of the nature of this material and constitutes an obstacle to the use of these fibers in certain projects, especially those that aim high performance. The above mentioned disadvantages are worrisome reasons for the occurrence of reduction in the strengthening capacity, as indicated by the rule of mixtures for composites [7]."

Jan 1, 2013

By Viktor Mukhin

"Among the methods proposed for spent activated carbon regeneration, the most acceptable is, thermal reactivation, because in this case the existing equipment for manufacture of activated carbon can be adapted for this purpose.In order to conduct the process of thermal re-activation of spent activated carbon directly at gold mills, a fullscale drum-type furnace with external electric heating has been developed, i.e. EPV-300 model with a throughput rate of 50 to 120 kg/hour. Its use ensures restoration of the adsorption properties of carbon up to the level of fresh activated carbon with an insignificant (by 0.7%) decrease in strength and with a high (95% to 97%) yield of reactivated carbon.During the recent years, activated powder carbon has been extensively used in flotation processes for treating polymetallic ores at ore treating plants to improve recoveries of main metals (copper, lead, nickel, etc.).Especially large volumes of activated powder carbon are used at the Talnakh concentrator of the Norilsk Mining and Metallurgical Complex in Russia for absorption of residual flotation reagents from recycled water in order to ensure efficient selective separation of minerals with similar physical and chemical properties.IntroductionSorption technology based on active carbons use starts being applied in such an important in the widest sense of the word strategical branch of economics as non-ferrous metallurgy. Thus since the middle ninetieth Russian gold extraction industry began to apply widely the processes of sorption from pulps and solutions by means of high-resistant granulated active carbons. That provided the start of gold ore minefield exploration, increasing of gold extraction from the ore and reducing its loss with the ""tails"" of process. At present more than 40% of Russian gold is extracted with the help of sorption technologies [1].Another field of active carbons application in non-ferrous metallurgy is the processes of non-ferrous ores floatation at ore-mining and processing enterprise. For that purpose powdered (less than l00µm) active carbons are used for providing the effective selection of minerals with similar physicochemical properties. This method not only increases the metal extraction level but provides deeper division of them."

Jan 1, 2008

By Petr Sulovsky, Pavel Leber, Jaroslava Ledererova, Miroslav Svoboda

"The properties of raw materials used for the production of building materials play an essential role in their choice. Industrial waste materials can in some cases improve the performance of new building materials, when compared with classical raw materials. The addition of waste can however negatively impact some of the building material´s characteristics, influencing its stability, service time, durability, and can introduce undesirable variation of certain characteristics over time. It is necessary that each secondary raw material intended for such use be thoroughly investigated in terms of its chemical, physical, and mechanical properties, with special attention paid to the risk components and risk parameters. It is necessary to make many- sided technological tests in relation to the required characteristics of the resulting materials for each chosen application. Moreover, the limit values for the critical (risk) parameters, which the given secondary raw material must satisfy to be used in a specific technology, need to be defined. Introduction The risk components in the industrial waste materials to be used in the production of building materials fall into two groups: - components that pose a risk of development (instant or delayed) of a process deleterious to the utility properties and durability of the resulting materials. Such processes include volume change (expansion as well as shrinkage), alkali-silica reaction, delayed ettringite formation, thaumassite attack, aggressive carbonation, etc. - elements or components that can, if released from the waste-containing building material, pollute the environment. They involve the so called potentially hazardous elements as well as compounds like fenols, PCB, PAHs etc. From the viewpoint of the presence of both groups of risk components, the wastes can be classified as: • environmentally inert waste materials. They are produced in the largest volumes and do not pose a threat to human health. Their physical and/or chemical characteristics fail to satisfy all requirements for utilization in ordinary production. The aim of technology design is to work them into the building products with suitable utility properties. • easier workable waste materials containing toxic components are produced in large volumes. In spite of the content of toxic components, their physical and chemical properties make them suitable for ordinary production, provided that the harmful substances are immobilized by the chosen technology."

Jan 1, 2008

By Alberto Oalvez, Lucya Yunus, Pengfii Tan

"Laboratory flotation tests of slow cooled converter slag have showed that 92.5% copper recovery at the copper cut-off grade of 24 - 25 % can be achieved by using a 50:50 ratio of DSP330 and SIBX (sodium isobutyl xanthate) at the natural pH of 7 and with a grinding time of 18.5 minutes. 70ìéç is the P80 achieved at this grinding time. MIBC is the frother and the solid content of the flotation feed was 46%. In the plant trials, two types of collectors at two different feed particle sizes for both the normal and slow cooled slag were operated. The particle size was controlled by the feed rate. The P80 of 75 ìçé at a feed rate between 32 - 36 t/h were tested. The plant trials have demonstrated that the copper recovery in the milling and flotation process of the slow cooled slags was improved by 3%. IntroductionIt is proposed to float the slow cooled converter slag, in the auxiliary circuit of the copper concentrator at Mount Isa, by using the processing conditions identified from several laboratory flotation tests. Among these laboratory tests, one produced a copper recovery of 4 % higher than those achieved from a normal cooled slag with the same slag feed grade and the same copper content (24 - 26 %) in the concentrate. These test conditions were selected for further studies.Laboratory Test Work and Plant TrialsThere has been a lot of work conducted under laboratory and plant conditions [1]. However, the achieved results did not justify their total implementation in the Mount Isa Copper Concentrator. Initially, the lab trials were carried out with slag cooled 100% in air; then it was changed to combined cooling for 12 h with air and 2.5 days with water sprays. The reason for this change was the shortage of space when the slag was cooled 100% in air, as it takes several days to achieve safe temperatures for its removal. The San Manuel Copper Smelter has reported that their slag was left for air cooling in pits for 8 h and then was followed by water cooling for 2-3 days [2]"

Jan 1, 2012

By E. Salinas-Rodriguez, J. Hernández-Ávila, E. O. Ávila-Dávila, A. Romero-Serrano, M. Perez-Labra, G. Juárez-López

"Single phase rubidium jarosite was synthesized by precipitation from aqueous solution. X-ray diffraction and SEM-EDS analyses showed that the synthetic rubidium jarosite formed in subspherical particles with an average particle size of about 35 µm. The chemical analysis showed an approximate composition of Rbo9432Fe3(SO4)2 1245(OH)6. The decomposition behaviour of the jarosite in terms of solution pH was thermodynamically modeled using FACTSage by constructing the potential-pH diagram at 298.15 K. The E-pH diagram showed that the decomposition of jarosite leads to goethite (FeOOH) together with Rb+ and SO42- ions. The experimental decomposition of the Rb-jarosite was carried out in alkaline solutions with five different Ca(OH)2 concentrations. The decomposition process showed an ""induction period"" followed y a progressive conversion period where the Rb+ and SO42- ions formed in the aqueous solution. In contrast, calcium was incorporated in the solid residue and iron was transformed into amorphous ferrihydrite. The kinetic analysis showed that this process can be represented by the unreacted-core chemically controlled model. The reaction order with respect to Ca(OH)2 is 0.4342 and the calculated activation energy is 98.70 kJ mol-1. IntroductionJarosite type compounds are hydrous sulfate minerals containing alkalis and ferric ions, MFe3(SO4)2(OH)6, where M can be H3O+· Na+, K+, Rb+, Ag+, NH4 +, Tl+, ½ Pb2+ or ½ Hg2+. Jarosite-type compounds were formed by the natural ""in situ"" oxidation of pyritic ores leading to the replacement of the original iron sulfides and iron oxides (Dutrizac and Kaiman) [1]. The great interest in jarosites is due to its ability to eliminate or diminish the iron concentration of the acid leach solutions produced in the hydrometallurgical zinc process, with relatively low losses of divalent metals such as Zn2+, Cd2+, Cu2+ or Co . However, the losses of the metal values demand a careful study of the conditions under which the jarosite compounds are formed together with their chemical properties."

Jan 1, 2012

The Port Kembla Copper (PKC) copper smelting facilities were commissioned during 2000. Numerous difficulties were encountered during the commissioning such as multiple reactor tuyere line failures, absorbing acid tower refractory collapse, and Noranda Reactor and Mitsubishi Converter process control problems. These problems are described along with the actions taken to overcome them. Process development is described particularly for the Mitsubishi Converter and Acid Plant.

Jan 1, 2002

By Kurt Westerlund

The design of the economically most profitable and technically most feasible smelter process gas handling .and treatment as an integrated part of the total metallurgical process is discussed and exemplified, with alternative flow sheets including material and energy balances, investment and operating costs. Retrofitting and de-bottlenecking of existing gas handling lines will be described and exemplified. Methods of increasing total gas handling line availability will be described.

Jan 1, 1992

By Martin J. Hansel, Jan Bäckström

Starting from historic perspectives on converting at the Rönnskär Smelter, the continuous developments of refractory practice is described. In the development the joint efforts of operators and suppliers of refractory have lead to significant achievements. This paper comprises the development of the converting process and the refractory lining as well as future prospects regarding operation and refractory lining design, especially in the face of equipment and raw material availability. 81

Jan 1, 2009

By Kurt Westerlund

The design of the economically most profitable and technically most feasible smelter process gas handing and treatment as an integrated part of the total metallurgical process is discussed and exemplified, with alternative flow sheets including material and energy balances, investment and operating costs. Retrofitting and de-bottlenecking of existing gas handling lines wil1 be described and exemplified. Methods of increasing total gas handling line availability will be described.

Jan 1, 1992

By H. Kohno

The Onahama No.3 tankhouse started commercial operation in early 1973, with the capacity of 8,500 metric tons per month. When the No.3 tankhouse was constructed, the starter sheet stripping section was rebuilt at the No.2 tankhouse and electrolyte purification section was expanded. The previous AIME paper in 1976 described the design principles of the No.3 tankhouse and its layout, This paper describes the starter sheet stripping machine in the No.2 tankhouse and the electrodes handling system in the No.3 tankhouse and all these equipments were developed for the operation of the No.3 tankhouse. A Hazelette continuous casting machine was also introduced in order to cast thin anodes with accurate shape. Owing to the adoption of thin anodes, gold, silver and copper inventory is reduced by 40%. Jumbo tanks and newly developed mechanical equipments were adopted and no work on cells during pulling up operation was achieved. Using thin anodes with accurate shape, inspection work was completely abolished while maintaining high current efficiency and high cathode quality. Labor cost was reduced by 70% and only six operaters can produce? 8,500 metric tons of cathodes per month. The same new electrolysis process is appreciated and has been used as a newly built independent tankhouse by Kidd Creek Mines Ltd., in Canada in 1981 with excellent results

Jan 1, 1987

By Jitka Jandová

A laboratory process based on simple and environmental friendly operation, aimed at recycling of spent Li/MnO2 batteries, is described in this study. This process involves roasting Li/MnO2 batteries in a vacuum furnace at 650°C, followed by selective leaching Li2CO3 from calcined electrode material in distilled water at ambient temperature and controlled crystallization of pure Li2CO3.

Jan 1, 2006

By Lifeng Zhang

The transport of fluid, heat and particles (bubbles and solid inclusions) in flowing molten steel is investigated in steel refining ladles, the continuous casting tundish, continuous casting mold and strand, and steel ingot casting processes. Inclusion removal from the molten steel by flow transport and bubble flotation, and inclusion growth by collision and diffusion are discussed. Removal of impurity elements such as [C] and [O] during steel refining are reported.

Jan 1, 2006