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By Hélio Wiebeck, Fabio J. Esper, Wildor T. Hennies, Guillermo R. Martín-Cortés, Francisco R. Valenzuela-Díaz

"Natural rubber reinforced commonly with carbon black to produce vulcanized material, turns into a new environmentally friendly nanocomposite when carbon black is replaced by organically modified clays of Brazil. Carbon black is substance derived from the oil refining process with consequent pollution to the environment. Its substitution in this industrial process must contribute to diminish the oil derived products dependence. As the added clays are only a third in weight of the traditionally carbon black added, then, to obtain the same final volume it is necessary to add low cost neutral filler that does not damage the technological characteristics of the final material. This paper presents results using as neutral filler of this type rice husk ashes from industrial wastes. Experiences realized with this nanocomposite material show results of quality and technological characteristics similar or superior to those of the rubber made with carbon black.IntroductionTraditionally rubbers are black or a very dark color. But they can have different appearance when filler of distinct composition of the carbon black is used. The carbon black is substance derived from the oil gotten during the final phases of the mineral fuel treatment with consequent pollution of the environment. Carbon black show nanometric grain sized distribution and a depth black color, because these properties it is also used for computer printers inks production. The substitution of this substance, traditionally used as a reinforced load in the rubber production, will have to contribute in such a way to diminish the dependence of these products as to diminish the pollution of the environment. The present work shows the results of the use of another kind of mineral nanoparticulate material substituting carbon black in the production of some rubber products. This nanoparticulate material is the organic modification of smectite clay treated with some types of ammonium quaternary."

Jan 1, 2008

By S. Ellor

The development of models of INCO's Copper Cliff operations using a computer spreadsheet program is discussed. Empirically developed metallurgical relationships were utilised. The paper concentrates on models of the pyrometallurgical processes but discusses applications such as optimisation of operating parameters, evaluation of feed changes and custom or recycle materials processing. The models were initially developed using a spreadsheet program on a personal computer. The requirements of plant engineers and process operators for significant increases in operating speed led to the transformation of some of the modules. The paper is presented in two parts: 1. The development of the modules using a spreadsheet. 2. The transformation of a module into a high speed tool for process control. The application of the technique to other pyrometallurgical processes is discussed.

Jan 1, 1992

By Bart Blanpain, Muxing Guo, Zhuangzhuang Liu

In order to stabilize free lime in the basic oxygen furnace (BOF) slag to achieve high value products, quartz sand and other additives are injected into slag. However, the current hot stage slag stabilization does not work in case of slag (before treatment) with a liquid fraction lower than 90%, where the slag containing solid particles is too viscous. Therefore, it is essential to understand how solid phases affect the viscosity of the slag system. In this study, the industrial BOF slags were investigated with respect to the correlation between volume fraction of solid phases and its viscosity. Slag viscosity was measured with a rotating type viscometer at temperatures below the liquidus. The volume fraction of solid phases was quantitatively calculated with FactSage. The Einstein-Roscoe equation was employed to predict the viscosity of BOF slag.

Jan 1, 2016

By Timothy W. Skszek, Adrian S. Sabau, Hebi Yin, Xiaoping Niu

The microstructure evolution during solution treatment plays an important role in mechanical properties of heat-treated aluminum alloys. In this paper, models were reviewed that can predict the microstructure evolution during the solutionizing process of the aging heat treatment of aluminum alloys. The dissolution ofMg2Si particles has been modeled as a diffusion process of Mg in the a-Al matrix. The evolution of volumetric fraction of fragmented silicon as a function of time and temperature was also considered. The growth and coarsening of silicon particles during the heat treatment was considered. It was found that constitutive equations and required property data for most of the phenomena that need to be considered are available. Several model parameters that need to be obtained from material characterization were identified. Pending the availability of these model parameters, this comprehensive model can be used to describe the microstructure evolution of aluminum alloys in order to optimize the solutionizing heat treatment for energy savings.

Jan 1, 2013

By Martin Reyes, Juan Hernández, Julio Cesar Juárez, Isauro Rivera, Ma. de los Ángeles Hernández, Francisco Patiño

The dissolution of Ag contained in metallurgical tailings was studied by adding ions Cu2+ and Zn2+ in S2O3 2- medium. Chemical analysis of mine tailings by cupellation revealed a Ag concentration of 71 g/ton. The XRF and XRD analysis confirmed the preponderance of SiO2 in the mineral matrix. The experimental dissolution process was conducted in alkaline solution using six concentrations of NaOH and five of S2O3 2-, at different temperatures, also using five concentrations of Cu2+ and Zn2+ as a catalyst. The results showed similar values for both systems (96.8% and 97.13%). The ion Cu2+ and Zn2+ increases the dissolution of Ag, and decrease the reaction time of dissolution. Under the conditions used, pH and stirring rate did not affect the dissolution of Ag.

Jan 1, 2015

By Chidchai Loyprasert, R. A. Stoehr

"A computer model has been developed to predict grain structures in alloys solidified under unidirectional flow using a combination of three techniques -- solution of the equations for flow of an incompressible fluid bounded by curved surfaces by the SOLA-SURF algorithm, calculation of heat flow by a finite difference method, and simulation of grain formation by a two-dimensional cellular automaton (CA) model. The changing rigid surface has been taken into account. Heterogeneous and homogeneous nucleation are considered, and the growth kinetics of a dendrite tip are evaluated by the Kurz-Giovanola-Trivedi (KGT) model. These calculations were applied to solidification of an Al-4.5% Cu alloy flowing over a chill on the bottom of a channel, a system for which experimental results were available. Using a variety of flow rates and superheats, agreement between the computed and experimental results were very good including transitions between columnar and equiaxed grains, the aspect ratio of the grains, and the inclination of the grains to the flow.IntroductionModeling of casting and solidification processes has developed over the years along two distinct tracks: (1.) modeling of macroscopic heat transfer and fluid flow for design purposes, and (2.) modeling of microscopic processes such as nucleation and growth in order to improve the scientific understanding of the phenomena involved. The present work is an attempt to combine the macroscopic and microscopic approaches for the solidification of an alloy flowing over a chill. The specific case chosen is that of an aluminum-4.5 % copper alloy flowing linearly over a water-cooled copper chill for which experimental results were available over a range of flow rates and superheats. For the macroscopic calculations, the SOLA-SURF algorithm for solution of the twodimensional fluid flow equations was combined with the finite difference method (FDM) for calculating heat transfer. For the microscopic calculations, heterogeneous and homogeneous nucleation were considered, and the growth kinetics at the dendrite tips were evaluated. The cellular automaton (CA) technique was used to apply the microscopic kinetics to the temperature and .flow conditions."

Jan 1, 1999

By Atsuhiro Nabei, Ken-ichi Yamaguchi

"Wet chlorination process of de-copperized anode slime is followed by de-chlorination stage in which lead-sulfate and metallic silver form silver residue. The silver residue is subsequently reduced to Ag2Se matte and PbO-SiO2 slag to remove lead to the slag in a short rotary furnace. Although this smelting process is proven well in actual operations, few papers have investigated its metallurgical aspects. This paper will describe the effectiveness of controlling parameters adopted at the Naoshima Smelter & Refinery and discuss the decisive factors influencing silver loss to PbO-SiO2 slag.IntroductionThe precious metals plant at Naoshima smelter & refinery was established in 1989, and has produced electrolytic silver, refined gold and platinum-group metals (PGM) from de-copperized anode slime as by-products of electrolytic copper. The process for gold production has been innovated from conventional smelting process to hydrometallurgical process since 2004 [1], while the process for silver production has still remained the same.The process for silver production at the Naoshima smelter & refinery is illustrated schematically in Figure 1. De-copperized anode slime is, at first, concentrated in the froth flotation process, then leached in the wet-chlorination process, and converted to silver residue in the de-chlorination process. The silver residue, which is a mixture of lead-sulfate and metallic silver, is charged to a short rotary furnace for the oxidation roasting to volatilize selenium dioxide and subsequent reduction smelting. In the smelting stage, silver residue and reverts containing selenium are smelted with flux and carbonaceous materials to form PbO-SiO2 slag and Ag2Se matte. Furthermore, Ag2Se matte is transferred to a rotary cupell and oxidized by air with the addition of sodium carbonate and sodium nitrate to produce silver anodes while removing impurities into litharge. Silver anodes are electrolytically refined by the Moebius process. Electrolytic silver is washed, dried and, finally, cast into 30kg-bars."

Jan 1, 2011

By W. D. Cho

The slag chemistry in steel processing plays an important role in terms of the removal of impurities including alumina particles. In the present study, the dissolution of solid aluimina particles in CaO-based fluxes at the temperatures between 1450 and 1550 °C has been investigated to determine dissolution kinetics and mechanism. Alumina particles were added directly in the slags and the size of alumina particles was measured as a function of time using optical and scanning electron microscopes. The dissolution rate has also been obtained as a function of Si02, CaF2, MgO and MnO contents in the slags. The diffusion boundary layer between alumina and bulk slag phase has been observed and analyzed using SEM and EDX. In addition, some experiments have been performed for the dissolution of alumina in BaO-based fluxes.

Jan 1, 2003

By Toshio Kurikami, Koichi Yamazaki

"Toho Zinc Co., Ltd Chigirishima Refinery has the production capacity of electrolytic lead for 95000t/y by sintering- blast furnace electrolytic process. Lead raw materials are lead concentrates, spent batteries and dusts that contain lead from other companies, and these are handled by existing smelting process. There are many circulation materials in the process, because the system has been constructed with improving the recovery rate and protecting the environment. This report describes material balance in each process, distribution of the lead and various components, and it examines present state of the processing. In addition, we report the result that we have tried to improve the work environment.IntroductionThe Chigirishima Refinery of the Toho Zinc Co., Ltd. is located in Chigirishima, an island 4km off the coast of Takehara-city, Hiroshima, Japan. The Chigirishima Refinery began lead smelting operations in 1951.The Chigirishima Refinery adopted the sintering-blast furnace-electrolytic process and has an electrolytic lead production capacity of 95,000 tons/year. The existing smelting process handles raw materials from lead concentrates, spent batteries, and lead-bearing dust from other companies. This system was constructed with the intentions of improving material recovery ratios and protecting the environment; therefore, there are many materials recirculating throughout the smelting process. This report describes the material balance in each process and the distribution ciflead and various components, and it examines the present state of processing. In addition, we report the results of our attempts to improve the work environment."

Jan 1, 2000

By Z. Smieszek, J. Botor, Z. Miczkowski, S. Sobierajski

"From 1978, the direct process for the smelting of chalcocite concentrates in a flash furnace by the Outokumpu method has been applied at the Glogów II copper smelter. The chemical composition of these concentrates make it necessary to control the process very strictly. In this paper, the method for controlling and measuring the main technological parameters of the copper production by flash smelting is being presented. It includes the determination of the chemical composition of the concentrate, its grain structure, the temperature of liquid products of the process, oxygen content in process gases, as well as lead concentration in copper and copper concentration in slag.The main process parameters are determined from the mass and energy balances. The relations between parameters, such as an effect of grain structure of a concentrate on oxygen and oil consumption, and dependence of chemical composition of a concentrate on capacity and products quality are discussed. 1. IntroductionThe Polish copper concentrates, as most concentrates occurring worldwide, contain from 18% to 30% Cu, and less sulphur (7-11%) and iron (2-5%). The main copper-bearing mineral contained in the concentrates is chalcocite, while bornite and chalcopyrite are present in smaller quantities. Moreover, the organic carbon (5-7.5%), arsenic (0.05-0.3%) and lead (1.2-3.0%) are also contained in the concentrates. The gangue consists mainly of silica, aluminosilicates, calcium carbonate and magnesium carbonate. Their proportions make the addition of slag-forming agents unnecessary.The composition of Polish concentrates, especially their low iron content, allows their application in the direct flash smelting process for blister copper production. Low sulphur content is the factor which determines the necessity of oxygen application in this process."

Jan 1, 1989

By M. G. Basavaraj, S. Sarkar, G. S. Gupta, P. D. Patil

"Previous experimental study on raceway size hysteresis on two-dimensional cold model showed that the inter-particle and wall-particle friction had a very large effect on the raceway size. Existing literature correlations for raceway size ignore the frictional effects. It has also been shown in the present study that their applicability to the ironmaking blast furnace is questionable. To take into account the effect of friction on the raceway size a stress analysis has been done for the raceway region. Two-dimensional fluid flow equations under turbulent conditions have been developed and solved computationally in order to get the pressure forces. The frictional forces were obtained in terms of stresses. To predict the raceway size a force balance was done for the raceway zone considering the pressure force, the frictional force and the bed weight. The resulting equations from the force balance are able to describe the raceway hysteresis phenomena reasonably well along with the raceway size. A two dimensional experimental set up has been fabricated in order to validate the computer predictions. Predicted values agree well with the experimental values.IntroductionWhen a high velocity blast of air is introduced into a packed bed through a tuyere, a cavity is formed in front of the tuyere. This cavity, formed in the iron-making blast furnace, is called the raceway. Coke tumbles down and bums in this raceway, generating heat and reducing gases for the iron-making process. The raceway is responsible for producing most of the reducing gasses in the blast furnace. In addition, the size and shape of the raceway determines the movement of solids within the blast furnace, the distribution of gases and liquids (slag and metal), setting the location where the primary chemical reactions occur and the temperature profile in the lower part of the blast furnace.Due to the importance of the raceway, many investigators l - 6 have studied it and have predicted the raceway size using the empirical correlations based on experimental (hot & cold) and mathematical models. A number of correlations have been reported in the literature to predict the raceway size by various investigators3 - 6 which are different to each other. Each of the correlations shows a different dependence of raceway diameter (DR) on bed height, particle size, solid density, bed voidage and blast velocity. None of the correlations includes the effect of solid stresses on the raceway size and shape. The magnitude of these stresses will depend on the bulk solids properties (internal angle of friction, wall angle of friction) and the bed dimensions."

Jan 1, 2001

By Dae Jin Ha

Sticking phenomenon occurring during hot rolling of two STS 430JlL ferritic stainless steels was analyzed by hot-rolling simulation tests. The sticking started from the initial nucleation stage in which the rolled materials were stuck onto the roll specimen surface, proceeded to the growth stage in which stuck fragments grew further, and reached the saturation stage. The modified 430JlL steel had a smaller number of sticking nucleation sites and slower growth rate than the conventional 430JlL steel because of higher high temperature hardness, thereby leading to less serious sticking. When the simulation test was conducted at 1070 °c, Cr oxides were formed on the surface of the rolled materials, and thus the sticking was drastically reduced because of the increased surface hardness of the rolled materials. In order to prevent the sticking, high-temperature properties of the rolled materials should be enhanced when rolled at 900°C or 1000 °C, and rolling conditions and alloying compositions, under which the oxide formation was promoted, were more important than high-temperature properties when rolled at higher temperatures than 1000 oC.

Jan 1, 2008

By Baokuan Li, Fang Wang

"Comparing with the single electrode in electroslag remelting processes, two series-connected electrodes have the advantage of little inductance, lower power consumption and higher melting rate, which was widely used to produce superalloys and specialty steels. Detailed understanding of the electromagnetic field distribution is essential for both improving ingot quality and saving electric energy. In the present work, a 3D finite element model was developed for the magnetic field, electromagnetic force, current density and Joule heating field of electro slag remelting processes (electrode, slag and ingot) with two series-connected electrodes using Maxwell equation, Lorentz law and Joule law. The results show that the maximum current distribute occur at the middle of electrode, due to the interaction of selfinduced and mutual-induced of two series-connected electrode; associated magnetic flux density on the inner side of electrode increase and the outer decrease; The maximum joule heating is at the interface of slag and electrode. The parameter study shows that if the current frequency is greater than 35Hz, the current density in inner electrode tend to linear distribution; with the increasing of original current, The maximum current density near the wall in electrode will increase linearly; with the increasing of electrode innnersion depth and decrease of slag cap thickness and the maximum of the joule heat in slag will increase.IntroductionElectroslag remelting processes(ESR) are widely used to produce superalloys and specialty steels [l-3l_Two pair, four pair or six pair electrodes in electroslag remelting processes is common in casting large scale ingot, which has the advantage of little inductance, lower power consumption and higher melting rate, comparing to singe electrode. They have the same essence with two electrodes in ESR.Compared to the single electrode ofESR, the other electrode is added which can decrease the reactive resistance and power consumption in the two electrodes of ESR. It is a complicated metallurgy process with a series physical and chemistry phenomenon from the molten of steel to the solidification of ingot [4-71_ These physical and chemistry phenomenon originated the effect of alternating current of high intensity. The rule of the alternating current of high intensity which revealed the law of physical and chemistry phenomenon in ESR is the precondition of improving ingot quality and saving electric energy. Jihe Wei and Yongli Ren[S-9lstudied the distribution of electromagnetic field in single electrode ofESR with Maxwell equation and relative electromagnetic theory. It had the limitation that take the electrode and mold as infinite conductivity. A detail analysis of Electromagnetic fields in ESR had been conducted by Patel A D [JO-llJ using general stream-function formulation. It is difficult to extend to three dimensions which could not be used widely. Daniel V [lZJ and Kharicha A [BJ only analysis the current density associated magnetic flux density field and temperature field without the whole irlformation of electromagnetic field. Maopeng Geng [l4J considered the current density and temperature field of the real and fake electrodes in ESR without skin effect. As to the complication of the two electrodes of ESR, it is rarely reported the electromagnetic field and Joule heating field of the two electrodes in ESR. The rule of effect of electromagnetic and modification of numerical simulation should be studied in depth."

Jan 1, 2011

By M. Demuth, B. Holleis, M. Potesser, D. Spoljaric

"In 2005, Messer Group established a technology competence centre for metallurgy in Gumpoldskirchen (Austria), with the aim to develop oxygen burners which satisfy today's and upcoming standards of legislation as well as customer requirements. With the assistance of the Development Sponsorship Fund (FFF) of Austria, cooperation with the University of Leoben was agreed on. With the long term experience of the Gas-Warme-Institut ""GWI"" in Essen (Germany) and the University of Leoben, different new burners have been developed.The efficiency of industrial combustion processes can be increased in two ways (which can be seen in Figure 1 ), either by preheating the fuel and combustion air or by adding oxygen. Due to the high 79 % Nz ballast in air combustion, only low flame temperatures can be reached. This results in high heat loss in the exhaust gas, caused by the low combustion efficiency. Oxygen can be introduced into the combustion chamber using different techniques:• Oxygen fuel burners• Direct oxygen injection into the fuel air flame• Underlaying of the fuel air flame• Enrichment of the combustion airIn Figure 2, the theoretical flame temperature for the stoichiometrical combustion of natural gas is plotted as a function of oxygen enrichment. Therefore, it can be concluded that even low enrichment values produce higher flame temperatures and result in higher combustion efficiency."

Jan 1, 2012

By A. V. Tarasov, V. M. Paretsky

"A mathematical model of the low-temperature (soft) nickel oxide reduction (SNOR) in a tubular kiln has been developed including an equation describing changes in the nickel oxide content of the solid material along the length of the kiln; an equation describing the changes in the content of reagents ensuring nickel reduction (i.e., hydrogen and carbon monoxide) in the gas phase along the kiln length; as well as the temperature along the kiln length. The kinetic relationships used for the development of the model had been determined based on experiments conducted specially for this purpose. Model investigations were conducted to determine the distribution of such parameters along the length of the kiln as the contents of metals oxides in the solids, partial pressure of hydrogen and carbon monoxide, variations of the temperature depending on the SNOR process conditions, including the kiln rotation speed. Based on the data obtained, a simplified regression model of the reducing roasting process was developed.IntroductionAt the SeveroNickel complex (Russia) a technology has been developed and is being introduced on a commercial scale for low-temperature (soft) nickel oxide reduction (SNOR) in tubular kilns.The SNOR process has a number of advantages, the main of which are the higher degree of metallization and higher chemical activity of reduced nickel oxide attributable to the lower fusion of the surface of the grains of reduced material due to lower process temperature (800-1000°C) and improved reducing ability of the gaseous phase. However, the fact that the process is conducted in a gaseous phase sets higher requirements to the consistency of its composition necessitating careful continuous monitoring and control of the main process parameters."

Jan 1, 2001

By Jiangtao Li, Zhongwei Zhao, Xingyu Chen, Xuheng Liu

In order to produce good quality ammonium paratungstate, Sn needs be removed efficiently from the tungstate processing solution. The nascent hydrous ferric oxide has excellent adsorption ability and is often used as an adsorbent to remove metal ions from aqueous solution. In this paper, nascent hydrous ferric oxide is used to remove Sn from tungstate solution. Through experimental, the effects of pH value, reagent amount of adsorbent, reaction temperature and reaction time on the Sn removal are investigated. The study shows that 98% of Sn can be removed effectively from sodium tungstate solution and only 2% of W is lost during process under the conditions of pH 9~12, reagent amount of Fe addition 40 times Sn amount, reaction time 30min and room temperature. As the Fe addition reaches 90 times of Sn concentration in the ammonium tungstate solution, 99% of Sn is removed and APT with zero level purity national standard is obtained.

Jan 1, 2014

By Liu Wei-feng

Base on the thermodynamic calculation of vapor pressure of lead, antimony and arsenic at high temperature, the possibility of separating lead, antimony and arsenic in different temperature was analyzed ,and the practice of producing qualified antimony white from lead-antimony alloy by direct blowing was introduced in detail in this paper. The blast furnace reduction smelting was brief introduced firstly, and then alkaline refining was applied to removing arsenic from lead-antimony alloy that contains As1%,Sb39%,Pb58%,the arsenic in the treated lead-antimony alloy could decrease to 0.009% by that method. The antimony white containing Sb2O3 99.5% could be produced by air blowing in the special furnace at 650? from the treated lead-antimony alloy. And the electrolytic lead could be achieved by electrolysis from the lead-rich alloy which contained 83% lead.With high-grade product being obtained the process was shortened. The technology has been applied successfully many years in Guangxi, China.

Jan 1, 2009

By James C. Sever

Two green field magnesium reduction plants are under consideration using dolomite as the raw material. The Calix calciner was independently selected for both plants. The unique design of this calciner is detailed and the advantages defined for the specific application. The low carbon foot print of this unit combined with the ability to capture food grade carbon dioxide makes this an environmentally proactive approach to carboniferous ore calcination.

Jan 1, 2015

By Leonel Contreras

The gas treatment system, MALIGAS (in Spanish MAnejo y Llmpieza de GASes which means handling and cleaning of gas), is part of the Codelco-Chile Potrerillos Smelter decontamination plan; which includes the newly designed system for the cooling and cleaning of the gas generated from a Teniente Converter and four Peirce Smith Converters. The gas generated in the process is captured by water cooled hoods and mixed with air. Then the gas enters a cooling pre-chamber which utilizes a water cooled screen to capture and remove the coarse and semi-fused particles. At this stage; the gas loses a portion of its heat with temperature falling below 608°C which is a necessary condition to avoid damage to the pipes, ducts and other metallic structure of the gas handling system. The gas is further cooled at the Radiation Cooler to a temperature ranging between 315 and 380°C. The gas is conditioned to avoid damage to the electrostatic precipitators that are designed to clean the gas by removing significant amount of dusts from the: gas stream. This gas stream is currently discharged to the stack, however, it will be treated in a sulfuric acid plant that is currently under construction and is scheduled for commissioning during the second half of 1999. The gas handing and cleaning system has been operated without any significant interruptions. Minimal emissions of SO2 and dusts in the work place are noted. The system requires minimum maintenance. The key to the high availability of the system is due to the good, performance of he Radiation Cooler, which efficiently cools the gas before entering the electrostatic precipitators (ESPs). This enables the ESPs to remove the dusts efficiently.

Jan 1, 1999

By E. B. Freidina

We have investigated a new electrochemical process for preparing lead-calcium alloys. Calcium metal, reduced fiom a molten chloride mixture, forms an alloy with liquid lead cathode. The addition of calcium carbonate to conventional CaC12-NaCl electrolyte enables us to avoid chlorine production on the anode and replace it with oxygen and carbon dioxide. The ternary system CaClz-NaC1-CaCO3 has a range of melt compositions, where the electrolysis can be held below 650°C. In order to prevent the side reaction of carbon deposition on the cathode we have separated the anolyte from the catholyte with alumina diaphragm. The factors, which affect the level of impurities and the current efficiency of the process, are discussed.

Jan 1, 1999