Search Documents

By A. McLean, Y. Uchida, M. Iwase, M. Myochin, K. Wiikimoto

"Phase diagrams of FeO-containing ternary systems could be derived from experimental data for the activities of FeO. The systems investigated are CaO-CaF2-FeO, SrO-SrF2-FeO; BaO-BaF2-FeO, CaO-CaCl2-FeO, SrO-SrC12-FeO, BaO-BaC12-FeO, CaO-A12O3-FeO and BaO-SiO2-FeO.IntroductionThe importance of phase diagram cannot be overemphasized. In a book, ""Alloy Phase Equilibria""[l], the author, Professor A Prince, states, ""A metallurgist has been defined as a person who thinks in terms of phase diagram"". Whether one accepts this statement or not, it is self-evident that an ability to interpret phase equilibria is essential to the professional metallurgists.The physical chemistry studies of iron and steelmaking process often require phase diagrams of FeO-containing slags. Iso-thermal section of the phase· diagrams of such systems can be derived from experimental data for chemical potentials of FeO. Due to the recent developments in the area of solid state electrochemistry, rapid determinations of the FeO activities have become possible. The present paper is aimed at documenting the derivation of the phase diagrams of FeO containing slags.Experimental AspectsAn electrochemical method incorporating stabilized zirconia can be used for the measurements of the activities of FeO in various slags and fluxes[2]. For the details of the experimental technique, reference should be made to reference 2"

Jan 1, 2000

By William Petruk

The concentrator of the Iron Ore Company of Canada consists of spiral circuits, a cone plant and a magnetics plant with regrind. The proportions of liberated and unliberated grains of iron oxides at each point throughout the concentrator were measured by image analysis, and recoveries were calculated for each particle type by the MATBAL materials balancing program. The results show that spirals and cones recover more than 92% of the liberated iron oxide grains in the size range of 848 to 150 um,, but the recovery drops off rapidly for finer grained particles. The tailings from the spirals and cones are reground and low intensity magnetic separators are used to recover liberated magnetite in the -37.5 um size range. The concentrator does not have a unit that efficiently recovers iron oxide grains in the size range of 150 to 37.5 um Consequently about 25% of the iron oxides in the ore are lost to tailings as liberated. grains in the size range of 150 to 37.5 um

Jan 1, 1989

By Lv Guozhi, Niu Liping, Liu Yan, Zhang Zhiqi, He Jicheng, Zhang Ting’an, Dou Zhihe

"CuCr alloy can be extensively used as contact materials in integrated circuit, electrodes, electric contact and high strength conductor. We proposed thermit reduction-electroslag remelting method of preparing the large scale CuCr alloy. But there are pores and oxide inclusions in CuCr alloy prepared by thermit reduction process. This paper studied mainly the effects of ratio of reactant and additive on the inclusion type and their occurrences in CuCr alloy. The slags and CuCr alloy were characterized respectively by XRD and SEM. The results show that when the additive is Na3AlF6, the slag consist of Al2O3 and Cr. When the additive is CaF2, the slag consist of Al2O3, Cr, CaF2 and CaAl4O7. The inclusions in CuCr alloy are mainly Al2O3 and pores which disperse in Cu-rich zone and Cu-Cr phase interface. When 5% CaF2 and 5% KClO3 are added, there are fewer pores and inclusions, and the more better microstructure.1 IntroduceCuCr alloy is the contact terminal material with an eximious properties[1,2], which gradually replaces CuBi alloy becoming the first choice for contact terminal material in the medium and high power vacuum switch after the 1970s. The traditional preparation methods of CuCr alloy mainly contain powder metallurgy, infiltration process and vacuum electric arc melting methods. But the above methods exist some shortcomings, such as poor product quality, high cost of production, processes complex ect[3-9]. CuCr alloy is made by the thermit reduction self-propagating method, which uses CuO, Cr2O3 and Al as raw material to get the high-temperature melt, and then casts to manufacture CuCr alloy ingot, which response equation follows as:"

Jan 1, 2012

By R. G. Reddy

Viscosities of alkaline metal oxide-silicate melts were estimated using our previously developed mathematical model. The structural based model considers depolymerization effects and related breakdown of the silicate network structure, on the addition of metal oxides to the melt. The developed expression: n =4.9x10 9 NO 0 T ½ exp(E/RT) poise was used to calculate the viscosities of various binary silicate systems such as, CaO-SiO,, MgO-SiO, and MnO-SiO,, as a function of temperature and composition. Excellent agreement was obtained between the calculated and experimentally determined viscosities.

Jan 1, 1991

By Li Qian

Mechanisms of bio-dephosphorization from iron ore was investigated in this Paper. The results show that there are two bio-dephosphorization ways from iron ore, the one is that Acidithiobacillus ferrooxidans directly derive phosphorus from the ore, the other is phosphorus is able to be leached acid produced during metabolizing of Acidithiobacillus ferrooxidans, and the latter is more important than the other. Adding suitable pyrite can enhance the bio- dephosphorization process through providing nourishment and producing acid directly due to S 3oxidized or indirectly due to Fe3 as oxidant. The potential varies in the range of 0.434~0.498V and pH is in the range of 2.5 ~ 1.25 during bio-leaching process. It can be founded that, according 2+to the E-pH graph of Fe-H2O system, Fe wouldn?t be oxidized under sterile system in this potential and pH ranges. It can be obviously concluded that the Acidithiobacillus ferrooxidans are 2+able to reduce the potential for the oxidization of Fe and make the oxidization occur in the above pH and potential zone, so the bio-leaching process can proceed. the investigation of E-pH graph of P-H2O system show that H3PO4 can exist steadily.

Jan 1, 2009

By Anja Pfennig, Thomas Böllinghaus, Marcus Wolf

During CCS components are exposed to a corrosive environment and mechanical stress which results in corrosion fatigue and is inevitably followed by the lifetime reduction of these components. The lifetime reduction of the cyclically loaded high alloyed stainless injectionpipe steel AISI 420C (X46Cr13, 1.4034) constantly exposed to highly corrosive CO2- saturated hot thermal water is demonstrated in in-situ-laboratory experiments (T = 60 °C, brine: Stuttgart Aquifer, flow rate: 30 l/h, CO2) in an environment similar to the on-shore CCS-site in the Northern German Bassin. In-situ tension-compression experiments were established simultaneously along with electrochemical measurements using a newly designed corrosion chamber in a resonant testing machine at a frequency as low as 30 – 40 Hz. In addition technical CO2 was introduced into the closed system at a rate close to 9 L/h. S-N plots, micrographic analysis and surface analysis of the fracture surface are demonstrated. X46Cr13 (surface roughness Rz = 4) reached the maximum number of cycles (12.5 x 106) at stress amplitude of 173 MPa producing a low scatter range of 1:3.5. Hydroxide and siderite layers were found on pits and crack surfaces. No typical fatigue limit exists. Pit corrosion prior to crack initiation may be identified as failure cause.

Jan 1, 2016

By Zhao-Qun Ke, Wen-Feng Tan, Jiang Diao, Yu-Hao Liu, Bing Xie, Zhang Tao, Wang Zhou, Hong-Yi Li

An effective way to decrease the dephosphorization burden in the current vanadium extraction-steelmaking process is slagging with CaO in vanadium extraction step. The phase composition of vanadium slag with different basicity and the regularities distribution of elements have been investigated by X-ray diffraction analysis and scanning electron microscopy combining with energy disperse X-ray spectrometry, respectively. The results indicate that V mainly concentrates in the spinel phases; Ca and P are rich in the silicate phases. Fe2SiO4 transform to CaFeSiO4, while the basicity of vanadium slag is 1.3. With further increase of basicity, 2CaOSiO2 could form in the silicate phases. Moreover, the phosphorus-containing phase will transform from Ca3(PO4)2 to Ca3(PO4)2-nCa2SiO4. With the increase of P2O5 content, the crystallization rate of spinels decrease obviously. Furthermore, the peak temperature for crystallization of spinels decrease 5 K with the P2O5 content increasing 1 wt%.

Mar 1, 2017

By J. -P. Nepper

It has been possible to largely contain converter aisle emissions of SO2 and fumes in the case of batch-wise operated Peirce Smith converters during normal blowing periods with the help of suitably designed primary hoods. Controlling the escape of off-gas during the periods of turning the converter in or out of the stack has been problematic in the past. Effective automated contro1 systems have been deve1oped for the purpose and successfully applied in smelter operations in Spain, Taiwan and Germany. This has led not only to an effective reduction of emissions in the converter environment but also to an improvement in the converter operation.

Jan 1, 1992

By M. A. Cocquerel

The future economic necessity of mining copper ores with a high impurity content and increased environmental awareness will require closer examination of the distribution of arsenic within copper smelting processes. A generalized approach is developed which can be adapted to specific projects for the determination of an overall process configuration to satisfy all requirements in a cost effective manner.

Jan 1, 1983

By Yuanbo Zhang, Guihong Han, Guanghui Li, Tao Jiang, Zengqing Sun, Yanfang Huang

"Because of small specific surface area and poor ballability, vanadium/titanium-bearing magnetite is difficult for production of oxidized pellet. A novel organic copolymer binder, modified humic acid (MHA), has been authorized recently in China. Effects of the novel MHA binder on the quality of V/Ti-bearing magnetite pellets are studied in this paper. Experimental results show the MHA binder can obviously improve the strength of green pellet. Because of better heat endurance, the MHA binder pellet has a higher strength than Peridur pellet under the same preheating conditions. Moreover, TFe grade of pellet with the MHA binder is much higher than that of the bentonite pellet. The strength of preheated pellet containing MHA binder of 0.25%~1.0% meets the requirements of oxidized pellet production by grate-kiln process. Comparatively, MHA is a promising orgainc binder for iron ore pellets. Its price is only one tenth of Peridur price and about 3 times of bentonite price.IntroductionThe iron-making practices show that the use of pellet is beneficial to blast furnace life, productivity and fuel savings. Therefore, many iron-making plants have expanded the production of oxidized pellets in order to meet the needs of modern large-scale blast furnaces [1]. Presently, bentonite is widely used to improve the quality of iron ore pellets. The negative effects of using bentonite include decreasing total iron (TFe) grade and degrading the metallurgical properties of the final products [2, 3]. Many studies, therefore, have been conducted on the application of organic binders to overcome the weakness of the inorganic bentonite. In comparison with inorganic binders, one of the biggest strengths of organic binders is low residual silica content [4]. However, those studies showed that the economics of foreign organic binder addition into pellets was not attractive. For example, the compression strength of preheated pellets and roasted pellets are both too low, resulting in powder generation and ring formation in the industrial rotary kiln [3, 4]."

Jan 1, 2011

By Shilai Yuan, Huimin Lu, Zhijiang Gao, Panpan Wang

"Solvent refining of silicon through using Si-Al melts is a valid method to remove the impurities from metallurgical grade silicon (MG-Si) melt. The thermodynamic behavior of impurities Fe, Al, Ca, Ti, Cu, C, B and P in MG-Si during the solidification of MG-Si was studied based on the available thermodynamic parameters and experimental data. The morphology of inclusions was investigated by Scanning Electron Microscope (SEM). The chemical composition of inclusions in MG-Si and Al-Si melt was analyzed by EPMA. It is found that the amount of white inclusion reduces and most impurities are solved into the Al-Si melts. After solidification of Si–Al alloy using induction heating and acid leaching, impurities can be effectively removed. The solidification of silicon from the Si–Al melt is found to be more effective for purification than general silicon solidification.IntroductionPhotovoltaic energy is one of promising energy resources in a sustainable society because of its inexhaustibility and cleanliness. Although the production and installation of solar cells have increased significantly during the last decade, the cost of solar cell installation is still high. Multicrystalline silicon has now become the main material in the photovoltaic market because of its low production cost and because of the relative high conversion efficiency of solar cells made from this material, which has been studied for a long time [1-3].Electronic grade (EG) silicon (99.9999999% Si) is commonly used as the raw material to produce SOG-Si (99.9999% Si). Silicon produced from the chemical routes restricts the development of solar cells due to environment threaten, high energy consumption and low productivity. Purification of metallurgical grade silicon (MG-Si) is a low cost, environment friendly method. Although several metallurgical processes such as directional solidification, vacuum refining and electron beam melting [4], have been developed, the cost reduction and refining efficiencies for manufacturing silicon is still have to be further optimized.In the purification process, it is difficult to remove boron and phosphorus by the conventional metal refining method. The refining efficiency depends on the segregation behavior of different elements in solid silicon and the liquid phase. The segregation ratios of all investigated impurities were found to be much smaller than the segregation coefficients between solid and liquid Al-Si melts [5]. For instance, the segregation coefficient of B in Si is 0.8 at the silicon melting point (1687K), whereas it is around 0.2 when silicon is solidified from Si-Al melt at 1273K. For phosphorus the segregation coefficient is 0.06 when silicon is solidified from Si-Al melt at 973K°C, which is much less than 0.35 for recrystallization from liquid silicon. Since the segregation coefficient of boron in silicon is 0.8, it cannot be removed by directional solidification."

Jan 1, 2014

By F. M. Wang, J. P. Lin, G. Y. Tang, H. C. Zhou, Y. F. Liang, F. Ye

"Fe-6.5%Si alloy is a very excellent soft magnetic material compared with conventional Si steel (Si content ~ 3.5%), especially in high frequencies with reduced iron losses and noises. But it is hard to be fabricated due to its brittleness at room temperature. Dynamic electropulsing is applied to the cold rolled Fe-6.5%Si sheet during tensile deformation. Mechanical and microstructural properties are investigated with different electropulsing and strain rate. It is found that the yield stress decreases and the elongation increases dramatically with the application of dynamic electropulsing. It is indicated that the work hardening could be reduced with the dynamic electropulsing during deformation, which provides a promising way to fabricate this alloy sheet much easier.Introduction Fe-6.5%Si (weight percent, same as below) alloy has more excellent soft magnetic properties compared with conventional silicon steel (Si content ~ 3.5%), such as higher resistivity, higher permeability, near zero magnetostriction, etc. and exhibits much lower core losses and noises [1]. However, Fe-6.5%Si is very brittle at room temperature and hard to be fabricated in strip by conventional hot-cold rolling process [2]. This lack of low-temperature ductility has been generally attributed to structural ordering ofB2 and D03 phases [3]. Several methods have been developed to avoid its brittleness, such as chemical vapor deposition (CVD) [4], rapid quenching [5, 6], dipping and diffusion [7, 8], direct powder rolling (DPR) [9], etc. However, hot-cold rolling method is still of interest for industrial applications. In our previous work, this alloy can be cold rolled after certain thermomechanical process and heat treatment [10-13]. The cold rolled sheet exhibits some extent of ductility [11]. However, side cracks are common for the rolled sheet, it is very necessary to improve the ductility of this alloy by other technical applications."

Jan 1, 2012

By J. P. Downey, T. Salisbury, M. Berlin, E. Rosenberg, G. Pinson, R. Christianson, K. Gleason, W. Gleason, S. Davis

"Direct digital manufacturing offers promise as a technique for fabricating complex hydrogen purification membrane support structures. Free form fabrication methods can produce parts with complex structures, and sintering parameters can be controlled to adjust the density, pore structure, pore pathways and strength in catalytic substrate constructs. Efforts are underway to define the influence of selected process variables on the chemical and mechanical properties.IntroductionThe Center for Advanced Mineral and Metallurgical Processes (CAMP), in collaboration with the Metallurgical and Materials Engineering Department at Montana Tech and the Chemistry Department at the University of Montana, is engaged in the development of new methods and materials for hydrogen purification membrane production. Because hydrogen readily passes through palladium, a structurally sound palladium-based membrane is capable of separating relatively pure hydrogen from other gases. In order for this technology to succeed, a suitable substrate material must be identified.High purity hydrogen is produced by various means. A common method involves a two-stage process for separating hydrogen from a hydrocarbon gas stream: 1) hydrogen-rich syngas is produced by the catalytic reaction of natural gas or another light hydrocarbon gas with steam, and 2) hydrogen is separated from the other syngas components by pressure swing adsorption (PSA) (US. Energy Information Agency, 2011). In PSA, gases enter a column that is packed with a material that absorbs gases as the chamber is filled and pressurized. As the pressure is slowly relieved, the absorbent material releases hydrogen at a higher pressure than the impurity gases. PSA processes produce 99.99% pure hydrogen at a high recovery rate. These systems typically demand a high capital investment due to the high pressure and multiple stages (columns) needed to attain high hydrogen production rates.Research geared toward reducing hydrogen production cost is focused on the development of improved catalysts and adsorbent materials as well as more effective single-stage separation processes. An interesting method combines hydrogen reduction catalysis and filtration. Nascent hydrogen is separated from other gases as it selectively permeates the filter. Catalyst filters may be made of gold, silver, platinum, palladium or precious metal alloys (Davis, 2009)."

Jan 1, 2012

By Yuanbo Zhang, Daoyuan Zhang, Youlian Zhou, Guanghui Li, Tao Jiang

"Modified humic acid (MHA) has been developed by Central South University (CSU) and authorized in China. It has been reported that MHA is an effective binder for oxidized pellets prepared from specularite concentrates. In this research, effects of MHA binder on roasting behaviors of the specularite pellets are studied. MHA is an organic binder, containing much carbon, hydrogen, oxygen, etc. During the roasting, MHA can provide some heat because of combustion of hydrocarbon, which is beneficial for the recrystallization of Fe2O3 in the specularite pellets at high temperature. Simultaneously, part of hematite particles within the pellets are firstly reduced to magnetite, then, magnetite is oxidized into secondary hematite, which obviously improves the roasting performance of specularite pellets.IntroductionOxidized pellets have been widely used in steel production as a kind of high quality burden for blast furnace ironmaking [1]. In recent years, production of oxidized pellets is developing very fast. Therefore, the supply of high quality magnetite concentrates, which is the most suitable for pellet production, becomes scarce. It is imperative to pursue new alternative materials for oxidized pellet production [2]. Specularite concentrates have attracted widespread attention due to the advantages of high total Fe grade and low impurity content. However, due to the poor ballability and firing performance, specularite has not yet been widely applied into pellet production [3, 4]."

Jan 1, 2012

By C. Ramasamy

The tariff reductions on imports, as a part of on-going liberalisation process in India, has fueled competition within and outside India and has, in turn provided an opportunity to reach global markets. This change calls for quality upgrades and cost-competitiveness without impairing the environment. In this context, gas based processes, contributing to improvement in quality and environment as well as processes where controls are applied when gases inimical to environment are involved, are discussed in a remelt/cast-house scenario. The impact of such processes on fabrication cost of sheet ingot is seen alongwith consumption and cost of materials and compared with a world class standard plant in North America.

Jan 1, 1996

By Laurentiu Nastac, Ruslan Mudryy

"This paper investigates the solidification of cast energetic materials. An active cooling and heating (ACH) technology and a mechanical vibration (MV) technology were applied to achieve unidirectional solidification during casting and to reduce cracks, gas pores, and shrinkage defects. The design parameters of these technologies were developed via Computational Fluid Dynamics (CFD) modeling and thermal stress analysis. Concerning the ACH technology, the number of cooling/heating sections and their temperature profiles and time sequences were optimized based on the thermo-physical properties of the energetic material as well as the riser and mold diameter, thickness and type. The ACH technology will also decrease the thermal stresses during casting of energetic materials and therefore minimize the formation of potential cracks that may form during the casting process. The MV technology will help to remove air entrapped during pouring process and decrease the detrimental gap size between the projectile and the solidified energetic material.IntroductionCasting processes are widely employed in the manufacture of products with intricate shapes and, in particular, in applications where the material of the final product is sensitive to machining. It is especially useful in processing of energetic materials. The cooling conditions applied in the casting process can affect the quality of the final cast in terms of void formation, residual stress distributions, and mold separation. Substantial shrinkage is also observed due to the density change upon solidification [1-3]. Residual stresses are known to be closely related to the formation of cold cracks and hot tears during casting. The formation of a gap between the mold and the cast material is of critical importance due to its deleterious effect on heat removal and on crack formation. In the casting of energetic materials all these defects can significantly impair the detonation velocity, Gurney energy, and insensitive munitions characteristics of the formulation, and lead to catastrophic accidents in explosives handling [ 4-5]. Imposition of carefully controlled cooling condition is thus critical in optimizing the cast quality that could help avoid such destructive effects."

Jan 1, 2013

By Mike Dry

While McCabe-Thiele plots are useful for designing single-component solvent extraction systems, not least because of their simplicity, they are less useful for multi-component solvent extraction. This paper presents a relatively simple method, compared to other approaches, for modelling solvent extraction as chemical equilibrium reactions between the various aqueous and organic species. The essence of this approach is how values for the equilibrium constants can be extracted from standard laboratory data. Synergistic solvent extraction of nickel is used to illustrate the method.

By Huimin Lu, Lian Zhou, Panpan Wang

"For the low concentration C02 exhaust gas from coal-fired power plant, steel plant emission trapping and recycle problem, a pressure swing adsorption process was studied, using a porous imidazolate framework materials (ZIFs) as adsorbent, separating carbon dioxide from fuel gas mixture. In the carbon dioxide reduction condition by electrochemical method, using ionic liquids as electrolyte, the oxygen and carbon products could be obtained, including carbon nanotube, nano carbon fiber and amorphous carbon. At last, a new C02 collection, recycling and reuse technology was formed.IntroductionDuring the combustion of fossil fuel in coal-fired power plant or steel plant, large amount of carbon dioxide has continuously emitted into the atmosphere. The phenomenon has resulted in the melt of arctic glacier and the frequent emergence of abnormal climate. How to reduce the emission of carbon dioxide and protect human living environment has become a worldwide challenge. Recently, there are three routes to resolve this problem: The first one is to adjust the energy structure and develop new energy, such as solar, wind, hydrogen; the second one is to improve energy efficiency and avoid waste; the third one is to research capture and sequestration of carbon dioxide (CCS). But many researchers have come to realize that the recovery and utilization of carbon dioxide are more important than the sequestration of it. Because the captured carbon dioxide just buried under the earth maybe cause secondary pollution if carbon dioxide leak out from the adsorbent."

Jan 1, 2013

By Waraporn Piyawit

Grinding sludge from the sintered neodymium-iron-boron (NdFeB) magnets production process was enriched with critical rare earth elements (neodymium, dysprosium and praseodymium), which can be up to 30% in the magnets. The demand of NdFeB magnets are simultaneously growing. Therefore, rare earths recovered from waste residue would reduce the demand of rare earth elements from primary sources. In this study, the feasibility of recycling rare earths through a hydrometallurgical process was investigated. The selective leaching of Nd from grinding sludge can successfully raise the rare earths concentration to 70%. The necessity of an oxidation pretreatment to improve the selectivity between Nd and Fe will be described.

By Tianzu Yang, Weifeng Liu, Lin Chen, Wei Chen, DUCHAO ZHANG, HUI XIAO

Oxygen-rich side blow bath smelting (OSBS) technology was developed in 2000 based on Vanyukov process. This technology exceeds the traditional pyrometallurgical methods by its great processing capability, high metal recovery and environmental-friendly property. In the past 15 years, OSBS technology extended its application area from lead industry to bismuth, antimony and waste recycling industries, etc. This paper introduces the history and new developments of OSBS technology. The typical industrial applications examples of the OSBS technology in China, including high lead slag reduction, low grade bismuth-lead concentrate smelting and metallurgical waste recycling, are reviewed. Especially, the unique furnace properties and technical parameters are compared. Finally, the potential research directions of OSBS technology are summarized.

Jan 1, 2016