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By Florian Kongoli

The production of a homogeneous self-fluxing sinter is an important step in iron making processes. A good sinler should have good permeability and reducibility and has to keep those characteristics for a certain time. An early melt down of the sinter in the blast furnace, where its solid state reduction is essential, would cause many problems such as low permeability and reductibility. Nevertheless, the important factors that influence these characteristics, such as the chemistry of the sinter and the fluxing effect during sintering and sinter reduction conditions have not yet been clarified, In today's new reality where many new minor components such as Al2O3 and MgO enter to the sinter through raw materials, the quantification of the fluxing effects during sintering becomes even more important. In this work, the liquidus surface and phase relations of the sinter primary melts in the CaO-FeO-Fe203-Si02 system at sintering conditions have been quantified. The fluxing effect of oxygen potential, Al2O3 and MgO has also been quantified by the means of some practical diagrams that can directly help the optimization of the sintering processes.

Jan 1, 2003

By Yong-ming Chen, Chao-bo Tang, Yun Li, Long-gang Ye, Sheng-hai Yang, Hao-tian Xue

In order to achieve high recovery of Cu and Co during cobalt-bearing copper sulphide ore smelting process, reducing agent (coke) and sulphidizing agent (pyrite) were added into molten smelter slag for reducing-sulphidizing smelting to product Cu-Co matte. Effects of reductive atmosphere, pyrite dosage, smelting temperature and smelting duration on Cu, Co, Fe distribution behaviours were investigated. The results show that the distributions of Cu and Co are mainly enriched in Cu-Co matte, and the distribution ratio, LCu and LCo, improve with increasing of coke amount or pyrite addition, whereas above 6 wt.% coke or 20 wt.% pyrite, Cu and Co tend to transfer from matte to cleaned slag. A properly high temperature(1300) and smelting duration(3h) are beneficial to the enhancement of the distribution ratio of valuable metals, and under the given set of conditions, LCu > LCo generally. However, an undesired high Fe contents in matte limit further increase of LCu and LCo.

Jan 1, 2015

By Deepu Philip, Pratik Agarwal, Ajay Kumar Shukla, Ishani Shukla, G Rajesh

Steel plants generally employ static BOF end point control models to arrive at a given temperature and chemistry at the end of blow. These end point models have now been supplemented with chaos control models to steer the blowing process in the right direction while the blow is in progress. Merely arriving at the correct end point temperature is however not adequate because in the subsequent stages as well the temperature variations can be large and unpredictable. The present paper deals with an integrated model to take into account the effect of all parameters affecting temperature and composition from tapping to the start of casting to minimize the use of LF or aluminum heating, and also minimize grade mixing. The application of lean operations strategy is explained in which the previous “Push System’ is changed to a “Pull System”, minimizing the use of ladle furnace or aluminum heating during steelmaking.

Jan 1, 2014

By Lin Zhu, Zheng Wei, Meng Li, Xueli Cao, Hanying Wen, Guodong Shi, Lei Yu, Wen-xin Tang, Tao Li

Low energy electron microscopy and photoemission electron microscopy (LEEM/PEEM), as powerful in-situ surface-sensitive electron microscopy, find wide applications in surface physics, chemistry and catalysis. The high reflectivity of incident low-energy electrons (0–100 eV), allows it to image the surface structures in the topmost few atomic layers within less than one second, while the sample can be heated up to 1200 °C in real time which is potentially very useful in metallurgy and materials fields. A unique three-prism aberration correction (ac-) LEEM was commissioned successfully in Chongqing University, with a lateral resolution below 2 nm. A multiple gas source in the ac-LEEM system was installed as well, which allowed us to observe chemical reactions of nanoscale mineral powders on metallic substrates. In this paper, the latest results on the applications of this three-prism ac-LEEM on oxidation and reduction processes on copper and iron polycrystalline surfaces are demonstrated.

Mar 1, 2018

By Jun Deng, Daohong Wu, Zhicheng Cao, Jingkun Tang, Luxing Feng, Xun Xue

The effect of reducing temperature, H2/CO mole ratio, and reduction gas flow rate on the metallization rate of oxide pellets were investigated at laboratory scale, with ludwigite iron concentrate used as raw materials. The reducing temperature varied from 850 to 950 °C, the H2/CO mole ratio changed from 1.5 to 4.5, the range of reduction gas flow rate was from 2 to 5 L/min. The results indicate that the metallization degree of pellets increase with increase of the temperature, H2/CO mole ratio, and gas flow rate. However, after temperature rises to 850 °C, metallization degree increases slowly. The effect of H2/CO on the metallization degree is not very obviously with the ratio of H2/CO increasing from 1.5 to 4.5. When the gas flow rate was increased from 2 to 3 L/min, the metallization degree increased greatly from 72.2 to 92.1%. In the flow range from 3 to 5 L/min, the metallization degree was increased slowly. The results obtained could be useful for comprehensive utilization of ludwigite iron concentrate by gas-based direct reduction method.

Mar 1, 2017

By Chengyi Ding, Xuewei Lv, Senwei Xuan, Chenguang Bai, Kai Tang, Gang Li

Sinter is an important iron-bearing material charged into blast furnace. Calcium ferrite (CF) is one of the most significant liquid phases in fluxed sinter. The isothermal reduction kinetics of CF and CF8M (n(CaO):n(Fe2O3) = 1, wt%(MgO) = 8) with 30% CO and 70% N2 gas mixtures at 1123, 1173, and 1223 K were investigated through thermogravimetric analysis in this study. Rate analysis illuminates that the reduction processes of CF and CF8M are mainly expressed as a typical two-stage reaction. Sharp analysis indicates that CF and CF8M reduction is expressed by the Avrami–Erofeev equation presenting a 2D shrinking layer reaction. The apparent activation energy values of CF and CF8M reduction are 46.9 and 31.8 kJ mol−1 individually based on model-free method.

Mar 1, 2018

By G. Djambazov, D. Shevchenko, D. Burnard, V. Bojarevics, K. A. Pericleous, W. Griffiths

Contactless ultrasound treatment can be useful for high-temperature or reactive alloys in the liquid state, where contact with an immersed vibrating probe is undesirable. The alternating component of the Lorentz force can generate sound pressure levels leading to cavitation of gas bubbles in the melt, through acoustic resonance. Resonance is a function of the speed of sound in the liquid, the shape of the volume containing it and surrounding boundary conditions. Induction forces applied to a crucible lead to bulk stirring and in general deform the free surface, whose precise shape may influence the resonance conditions. This effect is investigated here b ymulti-physics computer modelling. Calculated results for aluminium melts are compared with experimental data and conclusions are drawn as to the sensitivity to process parameters and the reliability of this type of ultrasound metal processing.

Mar 1, 2017

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 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 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 Fuqiang Zheng, Yufeng Guo, Guanzhou Qiu, Tao Jiang, Xiaoming Qu

MxTi3-xO5 is the main titanium-bearing mineral in the titanium-bearing electric furnace slag (TEFS), which is produced by direct reduction-electric furnace smelting process with vanadium titanomagnetite concentrate in Panzhihua-Xichang region of China. In order to effectively utilize the titanium resource in TEFS, the thermomechanical analysis and conditions for the growing up of MxTi3-xO5 grain were investigated, which emphasized on the effects of CaF2 and cooling rate on the crystallization of MxTi3-xO5 in the melting process. The mineral phase and morphology of titanium-bearing slag were determined by XRD and electron microscope technique, respectively. The results indicated that the average grain size of MxTi3-xO5 grown up from 30 to 92 lm and the area fraction of MxTi3-xO5 reached about 66% from 61% under the conditions of 5 wt% CaF2 and cooling rate at 1 °C/min.

Mar 1, 2017

By Xueqin Li, Xuewei Lv, Yu Zhang, Wenchao He

In recent years, a new process of “direct reduction-electric furnace smelting separation” has been put forward and developed for recovering the iron, vanadium, titanium and chromium to make full use of the chromium-bearing vanadium titanium magnetite. In the present work, FactSage, one of the most frequently-used thermodynamic calculation software, was used to calculate the migration of Fe, V, Cr and Ti with different nC/nO (mole ratio of carbon and oxygen). The calculation results indicate that the recoveries of Fe, V and Cr increase with increasing nC/nO and temperature respectively. In addition, the recoveries of Fe, V and Cr are up to 90% when the nC/nO value is more than 1.15.

Mar 1, 2018

By Shengli Wu, Binbin Du, Mingyin Kou, Laixin Wang, Kai Gu, Shun Yao, Heng Zhou

Coke plays an important role on the actual blast furnace production (BF), and its quality significantly influences the BF ironmaking process. In this study, the effects of physical properties, chemical composition and high-temperature properties of coke on main technical indexes of blast furnace were investigated. Some coke indexes were defined to evaluate the coke quality. The main technical indexes of BF include production, quality of HM, and fuel consumption. The quantitative relationship between coke quality and main technical indexes of BF were obtained after a series of statistical analysis. What’s more, the effect of these coke quality indexes on blast furnace smelting process was also explored, and all the relationships obtained from the analysis will provide a theoretical basis for the appropriate use of coke in blast furnace. The most reasonable range of coke quality indexes can be determined combining with the actual production as well.

Mar 1, 2018

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 Jin Yu, Fang-Qiu Zu, Yun Xi, Li-Na Mao

"According to the behaviors of resistivity-temperature of Cu-Sb70 melt, which suggests a partly reversible temperature-induced liquid structure transitions (LST) could occur in this alloy, in this paper, we investigated the dependence of solidification on the liquid state. Both resistivity and temperature were measured to track solidification process. The results show that the nucleating undercooling of the melt which experienced the LST increased and the solidified time decreased. Meanwhile, the solidified microstructures refined evidently, with the microscopic pattern of primary phase changes from disordered pillarlike dendrites into homotaxic ones. Moreover, it is verified that the microstructures would be different if the reversible part of the LST was restrained. The new phenomena and results reflected in this paper suggest that grasping the rules of melt structure change with temperature before material processing will give help for controlling the solidification more effectively and finally resulting in more ideal microstructures.IntroductionThe structure and quality of liquid alloys have a direct and important influence on the structure, performance and quality of the solidified ones. In recent years with in-depth study of liquid structure, researchers have found that some liquid structure transitions (LST) could occur on dependence of the temperature or pressure [1-5]. And the article [6] reported that a pressure-induced reversible LST was found in liquid triphenyl phosphite, which further confirmed the authenticity of the existence of the LST. Furthermore, in our earlier studies of Sn-based melts using resistivity method, some abnormal structure changes induced by temperature have been found at hundreds of degrees above liqiudus, and these LSTs are partly reversible[7]. This phenomenon has been discussed and it is suggested that the reversible LST in Sn-based melts are related to the short-range ordering (SRO) structures of Sn, which are tetrahedron structure with covalent bonding. However, does this reversible LST exist in other melts too?"

Jan 1, 2012

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 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