Search Documents

By Liangying Wen, Feng Xia, Chenguang Bai

"The situation of the Ti-V-Magnetite samples reduced with microwave has been investigated in laboratory. Firstly, the paper focuses on the heating behaviors of vanadium-titanium magnetite and characteristics of carbothermic reduction of V-Ti-magnetite in the microwave field. The effect of concentrate's size, quality on heating behaviors and reduction processes were researched. Results show that microwave heating may be a new heating resource replace of carbonic combustion reaction in reducing reaction. When the allocation of carbon is (16.7-30)%, carbothermic reduction of V-Ti-magnetite in the microwave field can proceed; with the increasing of carbon mixed, the metallization rate increases; and Fe, V can be reduced from their oxides in the microwave field; Titanic low oxide can be reduced from TiO2.1. IntroductionThe resource of Ti-V-Magnetite is abundant in the western area of Panzhihua in China, so far a mineral deposit of 4.64 billion tons have been proved up, it contains 14.75 million tons of V2O S which accounted for 87% of the vanadium and 5.93 hundred million tons of TiO2 accounted for 94% of the titanium resource respectively in China. The previous study proved that the major composition of mineral of the Ti-V-magnetite are Ti-magnetite, limonite, iron spinel, magnesium spinel etc, and the main elements of the Ti-V-magnetite in this area are Fe, Ti, V, Cr, Co, Ni, Ga, Sc etc[1] Due to the restrict of the BF-BOF process technical, during the smelting of the iron, the level of extracting the vanadium, titanium as well as other metal elements is limited. This results serious wasting of resources. To develop a new reduction process of Ti-V-magnetite is on the agenda, the microwave assistant reduction could meets this need, based on its characteristic of easy controlling of heating rate. To make use of the microwave energy to substitute the released heat sources of carbon combustion with air, use the solid phase state reduction at a relative lower temperature, make the beneficial element in Ti-V-magnetite transferred into the metal phase, then separated from the impurity. It is well worth to point out that once the microwave based reduction method has its industrial scale, it will take an outstanding position by its less release of carbon dioxide. This new environment-friendly process will play a vital role in the development of social industry and economy."

Jan 1, 2008

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 E. A. Trillo, L. E. Murr, R. D. Flores, J. C. McClure, B. M. Nowak

Complex vortex and swirl-like solid-state flow phenomena have been observed in the residual microstructures characterizing the friction-stir welding (FSW) of copper to 6061 aluminum; 2024 aluminum to 6061aluminum,2024 aluminum to 1100 aluminum, 2024 aluminum to 7039 aluminum and 2024 aluminum to 2195 aluminum. These flow phenomena are characterized by intercalation lamellae composed of dynamically recrystallized grain structures of the dissimilar metals which provide a super-plastic-like mechanism for the FSW flow in the solid state; there is no melting and temperatures at the weld center do not exceed about 0.8 TM (where TM is the absolute melting temperature (K)). In experiments to be described and illustrated, optical or light metallography (LM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques are utilized in examining residual FSW microstructures corresponding to tool rotation (stirring) speeds ranging from 400 to 1200 rpm, and traverse (or actual welding) speeds of 1 to 2 mrn/s.

Jan 1, 1999

By Wenqiang Bao, Qijie Zhai, Ting Wang, Shaobo Zheng, Huigai Li

The type of inclusions with different sizes in as-cast low carbon steel strip which is deoxidized by Si–Mn has been characterized by scanning electron microscope (SEM) and transmission electron microscopy (TEM). SEM observation and analysis suggested that the type of inclusions larger than 1 μm is manganese silicate. TEM analysis was carried out to investigate the composition and structure of nano-inclusions. Inclusions with diameter about 100 nm are manganese silicate, MnS–Si(Mn)Ox complex particles and isolated cubic Al2O3. Furthermore, HREM observations have revealed that there were two kinds of ultrafine particles in size range of 5–10 nm. One is spherical monoclinic Cu2S; the other is silicon-iron oxide particles with morphology of long strip. In addition, some thermodynamic calculations were performed to explain the corresponding relation between the type of inclusions and their size.

Mar 1, 2017

By Petrus Christiaan Pistorius, Farzin Fatollahi-Fard

The production of synthetic rutile—a common starting material for most titanium production processes—from iron-rich titanium minerals such as pseudorutile and ilmenite is described. The process for “upgrading” the mineral to synthetic rutile is by carbothermal reduction of the mineral while immersed in a molten salt at high temperature, followed by magnetic separation of the reduced iron. A variety of factors are also investigated, such as particle size of the mineral, the type of mineral, and the molten salt used. The solubility of iron(III) oxide in different molten salts is also experimentally determined.

Jan 1, 2016

By C. D. Seybert, J. W. Evans

"The elimination of convection is essential in experimental investigations of diffusive transport (of heat and matter) during solidification. This paper describes an investigation of an approach whereby a magnetic field gradient is applied to a electrically non-conducting diamagnetic liquid. A magnetic body force then arises which is dependent on the volume susceptibility of the liquid and thereby on the density. With the field gradient aligned vertically and of correct magnitude, the variation of gravitational body forces due to density variations (arising from temperature variations, for example) can be counterbalanced by a variation in magnetic body force.Preparatory to a study of convection control in diamagnetic liquids, PN measurements have been made of the convection occurring during the solidification of water. A peculiar flow arises because of the density maximum at 4°C. Modeling of the flow the steady-state solidification of water in an extremely high field magnet at the NHMFL indicates that flow can be significantly reduced, but it is suggested that, due to field gradient variations within the cell, flow cannot be completely halted. INTRODUCTIONNatural convection is inherently a part of terrestrial solidification. Density-based convection during solidification, due to gradients of temperature and/or concentration, has a significant effect on a material's properties. The design of products with specific material characteristics has required the development of many processes to control convection (such as in the growth of semiconductor crystals, and electromagnetic stirring in steel casting). The expansion of fundamental knowledge about the process of solidification requires collecting data in the absence of density-based convection, while most of science's solidification data (and thus the equations that science has fitted to those data) have been obtained under the influence of gravity. Only relatively recently, through clever experimental design (e.g., drop towers, high altitude parabolic flights, and space laboratories), have investigators been able to study solidification in an environment with ""micro-gravity""."

Jan 1, 2001

By J. B. Vander Sande, I. G. Solórzano, B. S. You, P. M. Jardim, W. W. Park

"Alloys with six different compositions in the system Mg-Ca-Zn were produced by melt spinning. The aging behavior of alloys was investigated by measuring the changes in microhardness after isochronal aging and the microstructure was analyzed by means of transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDS), scanning transmission electron microscopy (STEM) and scanning electron microscopy (SEM). All six compositions in the as-solidified condition show a difference in microstructure between the wheel contact side (zone A) and the free surface side (zone B) as a result of the differences in the solidification rate across the ribbons. One of the alloys (Mg-l.5wt%Ca-6wt%Zn) was chosen to be more deeply investigated in this work as it exhibited grain boundary films and an age hardening behavior was produced in that alloy.IntroductionMagnesium is the lightest of all the commonly used metals, and very attractive for applications in transportation. It also has a number of other desirable features, including good ductility, better damping characteristics than aluminum, and excellent castability. However, there are some negative features, such as high reactivity in the molten state, inferior fatigue and creep resistance as compared to aluminum, poor corrosion resistance and high production cost.In recent years there has been a significant increase in magnesium use as a structural material. These structural applications include aerospace, automotive and nuclear industries as well as appliances and sporting goods (1 ). According to reports on Mg-Zn alloys, the addition of Zn (2) in magnesium increased strength. Also, since the maximum solubility of Zn in magnesium is 6.2wt%, a considerable amount of Zn can be retained in solid solution in magnesium alloys by rapid solidification. In addition, Ca is known (3) to be one of the most potent alloying elements for refining the microstructure and precipitates in magnesium alloys, and also to improve mechanical strength and corrosion resistance."

Jan 1, 2000

By M. Oliazadeh

Spodumene [LiAl(Si2O6)] is the most common and desirable economic lithium-bearing mineral due to its high lithium content. In Canada, there are several spodumene deposits at the development stage that have the potential to help narrow the forecast lithium supply gap stemming from the widespread acceptance and increasing use of electric vehicles. Spodumene processing can be conducted using Dense Media Separation (DMS), flotation or combination of both. If spodumene liberation is sufficient at coarse particle sizes, DMS can be used for primary lithium concentrate production and silicate gangue minerals rejection. If liberation is not sufficient, flotation is then the main processing route for spodumene concentration. Even in cases where DMS is a viable beneficiation option, flotation may still be required to process the DMS middlings and/or the undersize fraction which is outside the particle size range for DMS. Considering flotation as a technique for spodumene beneficiation, there are several alternatives including the use of mechanical flotation cells, column flotation cells, coarse particle flotation cells, and/or Staged Flotation Reactors (SFR), either alone or in combination. Ore sorting can be incorporated at the start of the spodumene flowsheet to remove gangue minerals, particularly amphibole and pyroxene in the early stages. The main objective of flowsheet development for hard rock lithium deposits is to evaluate the ability of these options to produce a spodumene concentrate with a concentrate grade above 6% Li2O, lithium recovery of above 80%, and with the minimum operating and capital cost. This paper aims to describe the various processing options available for the beneficiation of spodumene from hard rock deposits and compare the associated operating and capital costs for each.

By Defeng Zhou, N. Trubaki, Jian Meng, Fanzhi Menga, Xiaojuan Liu, Yanjie Xia

"The microstructure and the electric conductivity of (Ce0.9Nd0.1)1 xMxO2 d (M=Mo, W) solid solutions were investigated. It has been found that their conductivity containing the grain (s gi ), the grain boundary (s gb) and the total conductivity (s t ) at 300°C- 700°C can be ranked as: (Ce 0. 9Nd 0. 1 ) 0.99 W 0.01 02- d (s gi = 0.065 S.cm·1, (s gb = 0.265 S.cm·1, s t = 0.039 S.cm-1) > (Ce0.9Nd0.1)0.99Mo0.01O2- d (s gi = 0.053 S.cm·1, s gb = 0.142 S.cm·1, s t = 0.029 S.cm-1) > Ce0.9Nd0.1 s 2- d (s gi 0.045 S.cm-1, s gb = 0.091 S.cm-1, s t = 0.018 S.cm-1) measured at 700°C. The highest conductivity is obtained in (Ceo.9Ndo.1)0.99W0.01O2 d. These results indicate that (Ceo.9Nd0.1)0.99W0.01O2- d is the most promising electrolyte materials of intermediate-temperature solid oxide fuel cells among (Ce0.9Nd0.1)1-xMxO2- d. IntroductionRare-earth (e.g. La3+, Nd3+, Gd3+ and Sm3l doped ceria-based ceramic materials have been acknowledged to be attractive electrolytes for solid oxide fuel cells operating below 600°C due to their high ionic conductivity [1, 2]. In order to improve ionic conductivity of these electrolytes further, in recent reports [3-6], some aids such as Mo03 [3] etc. in a limited amount can be used which causes extremely high conductivity. For example, Zhou et al. found that with MoO3 doping, the grain boundary conductivity of Nd3+ doped CeO2- d increased notably especially at lower temperatures due to the effect of severely undersized do pants [3]. It is well known that the size of W6+ (rw6+ = 0.60 Å) is close to Mo6+ (rMo6+ = 0.62A) because of lanthanide shrinkage. Thus, rare-earth doped ceria e.g. Nd3+ doped CeO2g with WO3 in a limited amount will be probably good and even better electrolytes. However, much less information is available about these materials. Therefore, in our paper, (Ce0.9Nd0.1)0.99 1-xMxO2- d (M=Mo, W) solid solutions have been prepared and characterized. Much higher conductive electrolytes are found in the series of (Ce0.9Nd0.1)0.99 M0.01O02- d particularly (Ce0.9Nd0.1)0.99W0.01O2- d"

Jan 1, 2012

By F. G. Prado

The technology for the extraction of zinc from zinc residues, such as zinc ashes, drosses and metallurgical flue dusts, by way of ammonium chloride solutions is well established, at least at the laboratory and bench scale levels. (3, 4) Zinc is soluble in ammonium chloride solutions in the form of zinc diammine chloride. Its solubility depends upon the concentrations and temperatures employed. The procedure and the equipment required are simple, and they can be applied either to small or large operations. As a by-product, zinc diammine chloride is produced with extremely low impurities in quantities which are stoichiometrically proportional to the zinc removed. The technology has been applied experimentally to galvanized steel residues. The dezincing results, including removal performance, energy and reagents required, and by-products are summarily presented in this paper.

Jan 1, 1992

By Wei Lv, Gangqiang Fan, Xuewei Lv, Kai Tang, Yingyi Zhang

The EAF smelting process of ilmenite concentrate consumes large amounts of energy. Semi-melting reduction can lower the reaction temperature and separate the iron and slag more thoroughly. However, this needs additives and pre-oxidation to promote the reaction. In this paper, the pre-oxidized ilmenite powders were reduced isothermally with graphite and Na2SO4. The influence of reduction conditions on the metallization ratio of samples, such as reaction temperature, and sodium sulfate additive were investigated. The results show that additive such as Na2SO4 can significantly decrease the melting point of pre-oxidized ilmenite concentrate.

Mar 1, 2017

By Shusen Cheng, Kun Yan

An elastic-plastic stress mathematical model of hot blast stove shell has been established in order to investigate the stress distribution and deformation of the shell. The results show that stress concentration happens along the intersection line of hot blast stove body and the hot blast manifold. The plastic deformation occurs on the hot blast outlet in blast period. The deformation degree of the hot blast shell near the blast outlet in blast period is much larger than that in combustion period. In blast period, the shell near the blast outlet elongates along the horizontal direction and shortens along the vertical direction, the shell near the outlet deforms into an oval. And in combustion period, its deformation isn’t obvious. The repeated deformation of the shell near the outlet between different periods may cause the refractory brick damage and be harmful to the long campaign life of hot blast stove.

Mar 1, 2017

By S. Y. Tan

As CMOS devices are scaled down into nano-region, SiO2 dielectric is approaching its physical and electrical limits. High-k material has been investigated widely in recent years, and gate oxide take place growth oxide with Hf-based below 45nm gate length technology node has been shown. The phenomenon of interfacial property between bulk silicon and gate dielectric materials (HfO2 and HfSiO) was focused. A comparison of capacitance-voltage (C-V) characteristic of gate insulator was presented. Furthermore, the electrical property and thermal stability of high-k dielectric materials at various post deposit anneal (PDA) temperatures were established. The X-Ray diffraction technique was (XRD) utilized to analyze crystallization of the thin films, and the X-ray photoelectron spectroscopy (XPS) was applied for surface chemical bounding energy to identify the silicon and dielectric layers. Results show that HfSiO films have exhibited a superior performance on both thermal stability and electrical performance.

Jan 1, 2009

By Hongli Wen, Guangkun Shen, Qiong Deng, Shoujian Huang, Min Gan, Xiaohui Fan

"Due to the low iron grade and high sulfur content, pyrite cinder is difficult to be directly used for iron-making. In this paper, technology of magnetic roasting -grinding and magnetic separation -acid leaching was put forward for reclamation of pyrite cinder. For pyrite cinder of TFe53.51%, S2.20 %, studies showed that good magnetic effect can be achieved at roasting temperature 650~7000, reducing atmosphere CO/(CO + C02) 10~20% and roasting time 10~30 minutes. In separation conditions of grinding size -0.045mm accounting for 96.09% and magnetic field intensity of 1240 GS, iron concentrate of TFe64.81 %, S0.18% and iron recovery rate 91.44% was achieved. Acid leaching was studied to strengthen desulfurization. Results showed that high-quality iron ore concentrate of TFe66.3 l %, S0.10% was obtained under the conditions of hydrochloric acid mass fraction of 5%, pulp density of30%, leaching temperature of70? and leaching time of2 hours.IntroductionPyrite cinder is produced as a by-product of sulfuric acid industry [1] Domestic production is more than 12 million tons every year and occupied area is over 10 million square meters [2,3]. The pyrite cinder outdoor not only pollutes air but also damages surrounding surface [4] It after treatment used for iron-making is an ideal reclamation approach for its rich iron which is commonly 40-60% [5]. But pyrite cinder gets low utilization for its low iron grade and high sulfur content in China [6]. Therefore, comprehensive utilization of pyrite cinder has profound significance to environmental protection and the development of domestic iron and steel industry."

Jan 1, 2013

By Robert H. Hsu

Palladium finely dispersed in a substrate of kieselguhr, Pd/k for short, has been successfully used for hydrogen storage, separation and pumping for a number of years at the Savannah River Site (SRS). Recently SRS has developed a new pd/k flow through bed (FTB) prototype for separating hydrogen from other gases and simultaneously storing the hydrogen on palladium. The FTB uses single-pass liquid nitrogen cooling during hydrogen absorption/separation/storage and electrical heating for desorption/unloading of hydrogen. Fourteen absorption-desorption or loading/unloading cycles using hydrogen have been conducted with the new FTB prototype. Test results show that all design performance objectives have been successfully achieved: recover 295% of hydrogen gas from feed gas, produce 99.9% hydrogen product gas and < 5% hydrogen in discharge gas. This paper will discuss characteristics of the palladium-coated kieselguhr or diatomaceous earth, design and operation of the FTB, and results of performance tests such as separation efficiency, hydrogen storage capacity and system heat transfer characteristics.

Jan 1, 2002

By Shusen Cheng, Dongdong Zhou, Yongqiang Bai

The strength of sinter could affect the permeability and CO gas utilization of blast furnace, and one of the main impacted factors of sinter strength is crack. With the widely use of vanadium-titanium sinter in China, the blast conditions of some blast furnaces became worse since the vanadium-titanium sinter has been added. However, there have little public research for this phenomenon. In this paper, the influence of titanium content on the sinter ore phase structure and crack were studied by DMRX polarizing microscope. In addition, the influence of basicity and oversintering on the sinter ore phase structure were also investigated. The observed results of vanadium-titanium sinter were compared with typical sinter in China, and the influence law of titanium content on the sinter ore crack was obtained.

Mar 1, 2017

By P. T. Velu, R. G. Reddy

"The use of emf measurements to derive classical thermochemical data has been in use for many years. The reaction associated with electrochemical process is harnessed in a galvanic cell and energy involved measured in terms of electromotive force. The property requirements of sensor electrodes used differ for various aqueous, molten salt and solid electrolyte systems. The electrodes for molten salt electrolytes need special care for construction. This paper describes the studies carried out using an Ag/ AgCI reference electrode. This electrode was used to measure the solubility of compounds in molten salt electrolytes. The results obtained using this electrode are in excellent agreement with the values from chemical analysis method.I. IntroductionThe technique of obtaining a metal from its oxides by electrolysis is more than a century old process now. In these processes, it has been well established that for halide electrolytes, only the dissolved oxides are available for the dissociation at the electrode to release the metal during electrolysis. Therefore, the solubility of metallic oxides in the molten salt electrolytes is an important parameter which determines the economical and technical viability of these processes. The widely used molten salts systems in halides are fluorides and chlorides. The fluoride electrolyte system is used in our present study.The viability of obtaining aluminum alloys by in-situ electrochemical processing has been outlined in our earlier publications[1-8]. Studies on the solubility of various alloying element compounds is a part of our ongoing research efforts for the direct production of Al-Li alloys. As mentioned above, the solubility of lithium oxide and lithium carbonate compounds in molten fluoride electrolyte system have studied using EMF technique. The change in potential of the molten electrolyte was measured by a working electrode against the reference electrode with the addition of lithium compound."

Jan 1, 1997

By Bart Blanpain, Tom Peter Jones, Muxing Guo, Liugang Chen, Huayue Shi

Fayalite based slag is formed during the smelting process of secondary copper resources. It was found that with the presence of high ZnO, the slag became viscous, causing a slag tapping problem. In the present paper, the phase relations of the slag system ZnO-“FeO”-SiO2-Al2O3- CaO (ZnO = 0-12 wt%, Al2O3% = 0-15 wt%, CaO = 0-1.5 wt%, with iron saturation) at 1150 °C is studied by using quenching technique followed by phase identification and compositional analysis of equilibrated samples. The dependence of FeO and Al2O3 solubility in the liquid slag on the chemical composition of slag is characterized. Based on the experimental data, the solid fraction of the slag, which may considerably, influences the slag viscosity, at the tapping temperature can be reasonably estimated and, therefore an appropriate modification of the slag composition can be made.

Jan 1, 2016

By Shinya Otsuka

Activity coefficient of oxygen in sulfide-rich and metal-rich melts in copper-sulfur binary were determined at 1423 and 1523 K by means of a modified coulometric titration technique using the following cell: 0 ( is Cu-S melts) I Zr02 (+Ca0) I air, Pt The activity coefficient values obtained in the present study increase rapidly with sulfur composition in the vicinity of xs = 0.3333. The data obtained for the matte saturated with the metal-rich melts are in good agreement with those obtained by Kuxmann and Benecke, Schmied 1, and Eguchi and Yazawa. Those obtained for the metal-rich melts are in good agreement with the results of Sano and Sakao.

Jan 1, 1983

By Gopalakrishna B. Prabhu, David L. Bourell

"Three mol% Yttria-Stabilized Tetragonal Zirconia (YSTZ) was prepared by a sol-gel synthesis technique using zirconium tetrachloride and hydrated yttrium chloride precursors. After drying and annealing at 823K, the particle size was in the range 10 to 20 nm. The zirconia powder was sintered using a uniaxial hot press at an applied stress of 20 to 40 MPa. One hour, isothermal sintering was performed in air after initial heating at 50K/min. Theoretical density was obtained at densification temperatures above 1498K. After sintering, grain coarsening characteristics were studied using constant heating rate anneals followed by quenching, based on a model for grain coarsening in a linear heating rate cycle. The microstructural change was studied using SEM and TEM and the phases were determined using x-ray diffraction.IntroductionThe ability to sinter nanocrystalline materials to full density several hundred degrees below the normal sintering temperatures is one reason for their current interest. [1-5] Yttria Stabilized Tetragonal Zirconia (YSTZ) of grain size of about 300 nm has exhibited superplasticity, with elongations as large as 800%.[6-7] Fine grain size is critical for superplasticity. Retention of the fine grain size during sintering of nanocrystalline powder is important if a material is to exhibit superplasticity or to exhibit physical or mechanical properties associated with the ultra fine structure. This paper investigates the sintering behavior and the grain coarsening characteristics ofnanocrystalline YSTZ.Techniques for synthesizing nanocrystalline materials have been studied in great detail earlier. [8-12] The techniques used to synthesize nanocrystalline zirconia include alkoxide synthesis [9], the chloride method [11], the peroxide method [13] and the acetone-toluene method. [13] In this paper the method used in the synthesis of zirconia is the chloride technique. With this precipitation technique, either zirconium chloride or oxychloride and a corresponding yttrium salt or even pure yttria are used."

Jan 1, 1994