Search Documents

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 Peter Sylvén, Darwin Morales

Despite being crucial for the smelting process, furnace tapping using oxygen lances has not been considered an operation that brings value. Therefore, these important tools have not seen a significant change in over 100 years. Problems related to the use of oxygen lances include: • Inaccurate tool: causing damages shortening the life of the taphole refractories. • Safety: extended exposure to the operator in an unsafe area of the furnace. • Cost: high oxygen consumption & high lance consumption. • Time consuming and frustrating to connect one lance to another. This paper will suggest a very good solution; new concept thermal lances. We will show how these provide an outstanding performance for a more efficient, faster and cost-effective furnace tapping operation. These new lances are very accurate tools that enable the operator to perform a more controlled operation; resulting in longer taphole life, fewer repairs and less down-time.

Jan 1, 2016

By Jian-hua Ren, Guang-liang Wu

A lot of dust is produced in iron and steel enterprises, giving rise to serious environment pollution, with which all countries are trying to find methods to deal. The influence of relevant technological factors on dephosphorization was investigated in laboratory, and the effect laws of that were analyzed. The results demonstrate that, in the given conditions of the best slag-metal proportion for hot metal dephosphorization is 1:10, and the optimum temperature is 1350 , The phosphorus distribution ratio of dephosphorization agent containing converter dust of 30% has the maximal value, with dephosphorization rate reaching 85%. Under the optimal conditions, premelting dephosphorization agent can significantly improve the ability of dephosphorization, dephosphorization efficiency increasing to 92%. Therefore, the dust can substitute the oxidant and fixative of dephosphorization agent, be used in hot metal dephosphorization, to enhance the efficiency of utilization.

Jan 1, 2016

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 Chengyi Ding, Xuewei Lv, Senwei Xuan, Jie Qiu, Yun Chen, Kai Tang

Isothermal reduction kinetics of CF2 by 30% CO and 70% N2 at 1123, 1173 and 1223 K was investigated by TGA in this study. The reduction rate analysis indicated that reduction of CF2 comprises three stages during the whole reduction process, Apparent activation energy of samples CF2 reduction is 34.37 kJ/mol. The ln-ln analysis implied the reduction of CF2 was expressed initially by a 2D subsequently by 3D shrinking layer reaction.

Mar 1, 2017

By Dongxing Wang, Zhang Ting-an, Xiaolong Li, Yan Liu

Recent years, bottom blown oxygen copper smelting process has been widely used in China. Besides many advantages such as autothermal operation, this technology is still in developing stage. This topic aims at promoting the dispersion of materials charged into the bottom blown smelting furnace used in the process. Based on the similarity theory, a 1/5 scaled physical model of smelting furnace was constructed. Polypropene particles were used as charged materials. High-speed camera was used to record the phenomenon of the particles dispersion under different gas-flow rates, nozzle diameters and installation angles of nozzles. Image processing software was used for obtaining the particles concentration under different conditions. Results show that when the gas flow rate increases, charged materials disperse better. With the same gas flow, the increasing of nozzle diameter promotes the dispersion effect of materials. The effects of installation angles are opposite for nozzles with diameter of 2.50 and 5.92 mm.

Mar 1, 2017

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 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, 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 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 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 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

By Xudong Liu, Feng Chen, Yufeng Guo, Wei Chen, Tao Jiang

Willemite is typically found in oxidized zinc ores and metallurgical secondary resources but without effective extraction method yet. Based on the ideas of zinc phase reconstruction in the willemite, the extraction of zinc from willemite by calcified-roasting using CaO as additive and ammonia-leaching process was studied in this paper. The influences of CaO dosage, roasting temperature, roasting time on the phase transformation and zinc leaching rate were studied, which were characterized by XRD. The results indicated that Zn2SiO4 was transformed into ZnO or Zn2CaSi2O7 .After roasted with 1.4 times of theoretical CaO dosage at l280 for 40 minutes, willemite was thoroughly transformed into ZnO. The zinc leaching rate of the roasted sample was 97.45% in NH4Cl-NH3 H2O leaching system, which increased by 91.40 % compared with zinc leaching rate of 6.05% when willemite was directly leached in NH4Cl-NH3 H2O system.

Jan 1, 2016

By Shusen Cheng, Kun Yan

A three-dimensional mathematical model of hot blast stove pipe shell has been established and used for analyzing the stress distribution and deformation. The results show that stress concentration happens along the intersection line of hot blast main and the hot blast manifold. There is no plastic deformation on the whole pipe region. The shell near the intersection elongates along the vertical direction and shortens along the horizontal direction, and deforms into an oval. The shell of hot blast main rises up, and inclines upward around the end of hot blast main. The hot blast main moves away from the hot blast and the displacement near the middle region is larger, the main deforms into an arch on horizontal surface. The deformation of shell may form a gap between shell and refractory inside and damage the security and stabilization of hot blast stove piping.

Mar 1, 2017