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By Christoph Sagadin

Corrosion mechanisms between high melting synthetic ferronickel slags and refractory were investigated. The used slags were prepared by mixing and melting of specific oxides. Substrates of the applied refractory material and specimens of FeNi slags were heated in a hot stage microscope up to 1650 °C. The experiments were performed under a defined gas atmosphere of 60% CO and 40% CO2. A further examination of the formed phases between slag and refractory occurred by scanning electron microscope. The investigations indicate that the slag penetrates between magnesia grains and partly dissolves magnesia. Spot analyses show that iron diffuses into the magnesia grains, which transform to magnesiawustite, meanwhile SiO2 forms different types of olivine like forsterite and monticellite. Thermodynamic calculations confirm the formation of these phases. The combination of practical lab scale experiments and thermodynamic calculations should finally contribute to an improvement of the refractory lifetime and performance.

By Dai Yongnian

The methods of treating zinc crust and its development in the last hundred years are compared and reviewed. There are better effects from normal pressure metallurgy turned into vacuum metallurgy. The traditional methods dezinc only. But we must consider that delead on further step. From lab tests to industrial scale experiment are researched. The first step-dezinc, second-delead, crude ,metal of, zinc, lead and silver are produced, The flowsheet of treating zinc crust are simplified, material consumption reduced, work condition improved, environment protect mended. This method is pointed out that its application can be expanded.

Jan 1, 1992

By Andrey V. Tarasov

To carry out a physicochemical substantiation of a transition to ?soft? modes of reduction of calcine obtained by desulfurizing roasting of nickel concentrate produced as a result of copper-nickel converter matte separation in a nickel anode production circuit, an analysis has been conducted of the macrokinetic behavior of actual calcine samples in the presence of gaseous H2-CO mixtures and solid reductant additives. Within a temperature range of 900°C to 1100°C the main regularities typical of the calcine reduction process with individual gases (H2, CO) also take place when using a gaseous mixture. Under the conditions of low-temperature (900°C to 1000°C) nickel oxide reduction with products of fuel oil conversion in the presence of coke, the role of the latter is insignificant from the technological viewpoint. As a result of the present investigations, we have obtained analytical expressions of macrokinetic parameters of the reaction interaction within the [NiO] calcine-H2-CO-C-CO2-H2O-O2-N2 system.

Jan 1, 2005

By Cheryl S. Lim

New technologies such as direct reduction and smelting reduction processes are increasingly being used in iron-making and steel-making in addition to conventional blast furnace technology. Critical parameters for control of these processes include the degree of metallization, degree of pre-reduction, and carbon and silica levels. On-line monitoring of these parameters is difficult because measurements often need to be made on hot ores (at or higher than -1000'C) in circumstances where representative sample streams are not readily accessible. A nuclear analyser has been developed which provides continuous, non¬intrusive, real-time measurements of iron, oxygen, carbon and silicon levels in hot ores undergoing reduction. The analyser has been tested in a plant using a direct smelting process on pre-reduced feed to the smelting vessel-, accuracies of 1% relative, 0.5 w'.96 (25% relative) and 1.0 wt.% (9% relative) were obtained for the degree of pre-reduction, carbon and silica respectively. The underlying method, capabilities and potential applications of the analyser will be discussed.

Jan 1, 2001

By W. Gutmannsbauer

Thin films of TiO2 nanoparticles have been prepared by different reactive deposition methods, such as electron evaporation, ion plating and ion beam sputtering. Many properties especially the optical properties, are strongly related to the film morphology and surface roughness. Scanning force microscopy was employed to obtain information on the surface structure of as-deposited Ti(h thin films. The influence of the deposition conditions and the film thickness on the optical and structural properties has been investigated. The as-deposited films were found to be amorphous or polycrystalline with anatase structure.

Jan 1, 1995

By Bingyi Bai, Wangjun Peng, Yanling Guo, Jieyu Zhang, Guoding Gao

The phase transformation of bayan obo ore with high concentration of iron and calcium was reduced at temperatures no more than 1000℃ were investigated in this study. The samples with insufficient carbon were treated at the temperature using a vertical furnace with a thermogravimetry (TG). The mineral phases and content were examined using Xray diffraction (XRD) and X-ray fluorescence spectroscopy (XRF) respectively. The complex phases of bayan obo ore transformed to some simple phases after treated with different content of carbon at the same temperature for 10 hours. The result of XRD、 XRF and TG showed that the reduction degree of Fe3O4 phase formation varied with the temperature and the carbon content of bayan obo ore.

Jan 1, 2015

By V. Montenegro

Smelting of copper concentrates in Teniente Converter produces highly oxidized slag, containing from 4 to 10 % Cu and from 15 to 25 % of Fe304. Copper recovery requires magnetite reduction at a level of 5%, determining the degree of cuprous oxide co-reduction and the liberation of copper matte inclusions. The rate of slag reduction is controlled by the mass transfer to the reaction interface. Slag stirring affects the rate of reduction and enhances coalescence of mechanically entrained copper matte inclusions. Slag reduction and sedimentation in the AC electric furnace is a commonly used method of slag cleaning. Utilization of DC electric furnace creates beneficial conditions introducing slag electrolysis additionally to chemical reductions with carbon of coke and electrodes. Application of external magnetic field, interacting with a direct current in an electric furnace, induces magnetohydrodynamic phenomena, such as intensive stirring and electromagnetic buoyancy force acting on inclusions. Laboratory scale research in simulated DC electric furnace with a superimposed magnetic field showed a significant acceleration of the rate of slag reduction and copper removal. Continuous measurement of gas flow and composition allowed for determination of the reduction rate along the time. Application of external magnetic field in the reduction of the industrial slag in a crucible simulated DC electric furnace results such as the increase of the reduction rate from 2 to 3 times, compared with the identical conditions in the AC electric furnace. Interaction of non- homogeneous electric field with crossed permanent magnetic field induces vigorous slag stirring, enhance mass transfer and accelerate the rate of the slag reduction. Additional participations of the slag electrolysis in the magnetite and cuprous oxide reduction as well as the acceleration of the settling of the inclusions by the electromagnetic buoyancy force affect the slag cleaning intensification.

Jan 1, 2003

By V. Montenegro

Smelting of copper concentrates in Teniente Converter produces highly oxidized slag, containing from 4 to 10 % Cu and from 15 to 25 % of Fe304. Copper recovery requires magnetite reduction at a level of 5%, determining the degree of cuprous oxide co-reduction and the liberation of copper matte inclusions. The rate of slag reduction is controlled by the mass transfer to the reaction interface. Slag stirring affects the rate of reduction and enhances coalescence of mechanically entrained copper matte inclusions. Slag reduction and sedimentation in the AC electric furnace is a commonly used method of slag cleaning. Utilization of DC electric furnace creates beneficial conditions introducing slag electrolysis additionally to chemical reductions with carbon of coke and electrodes. Application of external magnetic field, interacting with a direct current in an electric furnace, induces magnetohydrodynamic phenomena, such as intensive stirring and electromagnetic buoyancy force acting on inclusions. Laboratory scale research in simulated DC electric furnace with a superimposed magnetic field showed a significant acceleration of the rate of slag reduction and copper removal. Continuous measurement of gas flow and composition allowed for determination of the reduction rate along the time. Application of external magnetic field in the reduction of the industrial slag in a crucible simulated DC electric furnace results such as the increase of the reduction rate from 2 to 3 times, compared with the identical conditions in the AC electric furnace. Interaction of non-homogeneous electric field with crossed permanent magnetic field induces vigorous slag stirring, enhance mass transfer and accelerate the rate of the slag reduction. Additional participations of the slag electrolysis in the magnetite and cuprous oxide reduction as well as the acceleration of the settling of the inclusions by the electromagnetic buoyancy force affect the slag cleaning intensification.

Jan 1, 2003

By Alicia Esther Ares, Carlos Enrique Schvezov, Alejandra Silvina Roman, Claudia Marcela Méndez

In this paper the structure of aluminum based alloys and their corrosion behavior by using different electrochemical techniques as characterization methods are considered. Currently, it becomes imperative to know the role of the Al2Cu against the susceptibility to corrosion of these alloys. The present work aims to studying the electrochemical behavior of aluminum base alloys with the following compositions: Al-1wt.%Cu, Al-4.5wt.%Cu and Al-15wt.%Cu (with different grain structures), in 1M NaCl solutions, at room temperature. Cyclic potentiodynamic polarization tests were performed and were found that the alloys with more than 1wt.%Cu in the matrix have an unstable behavior and without tendency to reach passivity. The equivalent circuits derived from electrochemical impedance spectroscopy technique (EIS) generally showed two capacitive contributions. The susceptibility to corrosion becomes a complex function, not only of copper concentration and structure, but also with interdendritic spacings and distribution of phases in the alloys.

Jan 1, 2015

By A. S. Usmani

The flow associated with the pouring of molten metal into moulds has been modelled on the basis of certain simplifying assumptions. A finite element based Navier-Stokes equation solver has been used to analyse the flow. The velocities obtained from the Navier-Stokes equation solver are used to advect a pseudo-concentration function for modelling the fluid front. A simple problem with a known analytical solution is solved first to test the model. Subsequently, several more examples with varied geometrical configurations are modelled, including one with curved flow boundaries.

Jan 1, 1992

By Xie Zhang, Chongyang Zhao, Qingyun Huang, Bing Xie, Xiaopeng Zhen

"Extracting vanadium from vanadium containing hot metal into vanadium slag by BOF is the main vanadium production process in China. In this paper, the influence of Si content in hot metal on the quality of vanadium slag is analyzed. Synthetic vanadium slag with different SiO2 content were melted at 1673 K and then cooled to 303K at the cooling rate of 3?/min. Optical microscopy, SEM, EDS and XRD were used to analyze the mineralogical phases and crystallization behavior of vanadium slag. The results show that vanadium slag mainly contains spinel phase and silicate phase; V is enriched in the spinel phases while Si is concentrated in Fe2SiO4 CaFeSi2O6 and (Fe,Mn)2SiO4 as silicate phase. The melting point of slag increases gradually with the addition of SiO2; whereas viscosity decreases with an addition of 15~19% SiO2 and increases with an addition of 19~27% SiO2.IntroductionVanadium is an important element which is used almost exclusively in ferrous and non-ferrous alloys. The major vanadium products include FeV, V2O5, V2O3, VN and Al-V-Ti alloy. Furthermore, vanadium slags are mostly produced by oxidizing the elements in V-containing hot metal during a duplex refining process. Therefore, the process of removing vanadium from hot metal has its significance on the subsequent process[1].The extraction of vanadium is greatly affected by the mineralogical composition of vanadium slag[2], the distribution of the elements between the spinel and silicate phases and its physic-chemical properties. These characteristics of vanadium slag have been studied in some details. It has been reported that Si mainly exists mainly in the form of silicate which wraps the spinel crystals while small amount of Si stands as phosphorus quartz or diopside[2]. Chen et al.[3, 4] points out, when SiO2 content in vanadium slag increased every 1%, V2O5 decreased 1.48%. Moreover, silicate phases would embarrass the oxidation of V-containing spinels through decreasing the exposing probability[5]. Meanwhile, melting point and viscosity of vanadium slag has been greatly influenced by the SiO2 content. Therefore, this work attempts to analyze the above-mentioned questions systematically."

Jan 1, 2012

By K. Morsi

Carbon nanotube (CNT) reinforced metallic composites have been recently generating significant scientific interest, due to their expected superior properties compared with other composites. Out of the metallic matrices investigated for reinforcement with CNTs, aluminum has received considerable attention. A major problem has been the dispersion of CNTs in metallic matrices. This paper discusses preliminary results on the mechanical dispersion of CNTs in aluminum powder, powder processing, stability and characterization of aluminum dispersed with CNTs at reinforcement levels equal to and below 5 wt.%.

Jan 1, 2009

By S. G. Kumar

Experimental studies on high carbon steelmaking through LD Converter - Vacuum Arc Degassing - Bottom Pouring route to produce low oxygen steels were carried out. The results indicated that it is possible to produce steel with a total oxygen content of less than 15 ppm. Thermodynamic and mass balance calculations are made on low-carbon steels that are treated by a complex deoxidation practice based on primary deoxidation of aluminum, manganese and silicon additions; followed by secondary deoxidation of vacuum degassing with simultaneous additions of aluminum. The results showed that primary deoxidation is mainly due to aluminum and the effect of carbon under reduced pressures on deoxidation of molten steel that is already killed by aluminum is negligible. The effect of process parameters on total oxygen content of steel, like carbon content, slag composition and inert gas purging, are discussed.

Jan 1, 1994

By William Petrul

Image analysis studies were performed on mill products from laboratory flotation tests of the Zn-Pb ore from the Faro deposit in Yukon, Canada, to determine mineral liberations at specific grinds and to predict recoveries at optimum flotation conditions. The minimum and optimum grinds for liberating sphalerite and galena were predicted from size analysis data for the minerals in large ore pieces, and determined by image analysis studies of the mill products. The determined optimum grinds are about 2 Tyler mesh sizes larger than predicted because sane of the fine grained sphalerite and galena occurs in interstices between coarser grained pyrite and is liberated when the pyrite grains are broken apart. Materials balance calculations were performed on the analyzed values for the liberated and unliberated sphalerite and galenaa to determine their distributions in the mill products. The laboratory flotation tests recovered 74% of the sphalerite and 83% of the galena in Zn and Pb concentrates respectively. The mineral evaluation study indicates that the optimum recovery for sphalerite and galena are 85 and 83% respectively. The company is currently recovering 80% 'of the sphalerite and 82% of the galena.

Jan 1, 1989

By K. D. Mondale

The chemical and physical properties of samples from ten sedimentary zeolite deposits. (representing chabazite, clinoptilolite, erionite and mordenite types), have been determined as a prelude to the development of a wet beneficiation process. The mineralogical composition of each deposit and such properties as morphology, size, apparent density, surface area, pore volume, relative hardness and zeta potential in solution have been determined. Some of these properties, especially apparent density and relative hardness, were found to differ significantly from textbook values. Based on differences in properties between the zeolites and their associated gangue minerals, a wet beneficiation process has been developed which makes use of selective grinding, sizing, sorting and gravity concentration. Additionally, an alternative upgrading process using flotation has been developed for one of the deposits.

Jan 1, 1988

By Qiang Zhang

Hybrid composites are fabricated by adding two reinforcements into matrix materials so that the expected excellent properties can be achieved through the combined advantages of short fibers, and different size particles (micron or submicron), which provide a high degree of design freedom. In this paper, hybrid preforms were produced with the different size reinforcement of the Al2O3 particles and short fibers. The Al-Si alloy-based hybrid composites were fabricated by preform-squeezing casting route. The structure and performance of composite materials were studied with the Transmission Electron Microscopy (TEM), and Scanning Electron Microscopy (SEM). The results show that the reinforcements, both particles and fibers, distribute homogeneously in the matrix materials, and the properties of composites are found to improve in comparison with the matrix Al-Si alloy.

Jan 1, 2009

By Peter Stiaszny, Andrej Samoilov, Yuri Titovets, Gottfried Hribernig, Nikolai Zolotorevskii

"The model has been developed to simultaneously predict both transformation product portions and mean ferrite grain size from the same common · principles as a result of the austenite decomposition during any cooling path of dual phase steels. The transformation products considered are polygonal ferrite, pearlite, bainite and martensite. The model is based on the classical equations of nucleation-growth theory and also contains some empirical parameters. The chemical driving forces for nucleation and composition of elements at the phase interfaces are derived by computation thermodynamics. The empirical parameters related to the model were determined on the basis of a series of austenite transformation dilatometric curves and grain size measurements for continuous and interrupted cooling of several steel types. The model is aimed to predict phase transformation in the complex cooling conditions of the run-out table of the hot strip mill at YOEST-ALPINE STAHL LINZ GmbH as a part of the computer aided system for prediction and on-line controlling of the mechanical properties of hot-rolled strip.IntroductionThe term ""dual phase steels"" is used to refer to a steel consisting essentially of a dispersion of martensite in a fine-grained ferrite matrix. These steels are of increasing technological interest since they provide a better combination of strength and ductility than any other conventional steel sheet material. The strength is important because it offers an opportunity to produce lighter components, while good ductility is needed to permit easy forming of components. It is generally recognized that martensite plays an important role in determining the strength level of dual phase steels. A full understanding of the role played by the phases in determining such characteristics requires investigating in more detail how to optimize the martensite level of such steels, while maintaining good ductility remains the subject of continued research in the industry."

Jan 1, 2000

By Dan Wang, Yuanbo Zhang, Guihong Han, Guanghui Li, Tao Jiang, Yanfang Huang

"Hematite concentrates are characterized by bad high-temperature reactivity and poor balling index, which restrict their large-scale application in the production of oxidized pellets. An organic additive, namely MHA, was authorized and used as binder recently in China. Compared with bentonite, the effects of MHA on compressive strength of hematite pellets at various firing conditions were investigated in this study. Experimental results showed the compressive strengths of preheated pellets with different binders were increased with increasing the preheating temperature and time. The compressive strength of preheated pellets with MHA binder was lower than that of pellets with bentonite, which can be ascribed to the high porosity of pellets with MHA binder. However, the compressive strength of roasted pellets with MHA binder was higher than that of pellets with bentonite. The compressive strength of finished pellets balled with MHA binder 1.0 wt% could meet the operation requirements of grate-kiln process.IntroductionHematite concentrates are characterized by bad high-temperature reactivity and poor balling index, which can lead to the appearance of those problems with increasing the energy consumption, shortening the useful life of equipment, and finally increasing the operation cost of oxidized pellets plants [1-2]. Some investigations have been conducted based on improving the pelletizing technique of hematite concentrates, such as pretreatment of raw materials [3-7], optimization of ore proportioning [8], addition of solid fuels [9-16], and so on. Employing high pressure grinding roller for the treatment of hematite concentrates revealed that the mechanical strength of wet green pellets could be improved. However, the mechanical strength of fired pellets was not improved obviously [7]. Huang, et al., pointed out that the preheating and roasting temperature may be decreased and the compressive strength of fired pellets could be increased by blending a certain proportion of magnetite concentrates with hematite [8]. Nevertheless, there are a variety of magnetite ores different in physical and chemical properties in China, resulting in the instability operation [17]."

Jan 1, 2012

By L. Lewczuk

A detailed mineralogical and liberation study was performed on the iron ore mill products from the Scully concentrator of Wabush Mines, Newfoundland. Automated image analysis techniques were applied to deter-mine grain size distribution and liberation of all mineral components of the ore. As a result of the study it was indicated that iron recovery can be improved and the Mn minerals reduced in the iron ore concentrate by (a) increasing spiral middlings, (b) regrinding the middlings, and (c) separating the Mn minerals from the iron minerals in the reground middlings.

Jan 1, 1988

By Beate Ina Jenssen

Ferric iron removal from the nickel electrolyte at Glencore Nikkelverk AS in Kristiansand, Norway, is achieved by precipitation of iron hydroxide followed by filtration, and it is desirable to improve filtration properties of the precipitated iron hydroxide in order to decrease the filtration time. The effect of increasing the residence time from the current 45 min to 75 min and temperature from 65 °C to 90 °C on the filtration properties of the precipitated iron hydroxide (akaganéite) was studied by simulating the industrial process conditions in a continuous reactor setup operating at steady state, using ferrous-containing process solution as feed material. It was possible to decrease the filter cake resistance by both increasing residence time and temperature, but temperature gave the most pronounced effect and reduced the filter cake resistance by one order of magnitude.