One of the bottlenecks of the blast furnace （BF） campaign is the life length of hearth bottom. The basic reason for the erosion of hearth bottom is its direct contact with hot metal. According to the theory of heat ...One of the bottlenecks of the blast furnace （BF） campaign is the life length of hearth bottom. The basic reason for the erosion of hearth bottom is its direct contact with hot metal. According to the theory of heat transfer, models of BF hearth bottom are built based on the actual examples using software and VC language, and the calculated results are in good agreement with the data of BF dissection after blowing out. The temperature distribution and the capability of the resistance to erosion for different structures of hearth bottom are analyzed, especially the two prevalent kinds of hearth bottom arrangements called ＂the method of heat transfer＂ for all-carbon brick bottom and ＂the method of heat isolation＂ for ceramic synthetic hearth bottom. Features of the two kinds of hearth bottoms are analyzed. Also the different ways of protecting the hearth bottom are clarified, according to some actual examples. After that, the same essence of prolonging life, and the fact that the existence of a ＂protective skull＂ with low thermal conductivity between the hot metal and brick layers is of utmost importance are shown.展开更多
Steel plate cold common （SPCC） is a Al-killed steel with Ca-treatment. The control of Al2O3 inclusion into low melting point liquid region is beneficial for inclusion removal, cast-ability promotion and defects redu...Steel plate cold common （SPCC） is a Al-killed steel with Ca-treatment. The control of Al2O3 inclusion into low melting point liquid region is beneficial for inclusion removal, cast-ability promotion and defects reduction during rolling. Thus it is essential to understand steel-inclusion equilibrium since inclusion composition is determined by composition of liquid steel directly through steel-inclusion reaction. Thermodynamic calculation software FactSage is performed to understand how to control inclusion composition during ladle furnace （LF） refining, and industrial trials are carried out to verify calculated results. Firstly, target region for controlling CaO-Al2O3-MgO ternary inclusion is analyzed on the basis of the ternary phase diagram and the relationship between activities related to pure solid and activities related to pure liquid was fixed by thermodynamic analysis in order to obtain reliable activities for components of inclusions in the target region by FactSage. In addition, inclusions in steel samples are detected by scanning electron microscopy （SEM） combined with energy dispersive spectroscopy （EDS）. It is found that most of Al2O3 inclusions are modified into lower melting point region but a number of them are still located in high melting point region at the end of LF refining after Ca-treatment. Moreover, the composition of liquid steel equilibrating with liquid CaO-Al2O3-MgO inclusion is obtained by steel-inclusion equilibrium calculation when w[Al]s is approximating 0.03% as： a[O] is 1.0×10-6 to 4.0×10-6, w[Ca] is 20×10-6 to 50×10-6 and w[Mg] is 0.1×10-6 to 3.0×10-6. At last, stability diagrams of various calcium aluminates and CaS are established and they show that liquid calcium aluminate inclusions form when w[Ca] is more than 20×10-6, but CaS precipitation is difficult to prevent because sufficiently low w[S] （〈0.003%） is required.展开更多
Many problems appear in the sintering process of vanadium-bearing titanomagnetite, such as high energy consumption and low productivity; simer quality is also very poor for its low tumble strength and high reduction d...Many problems appear in the sintering process of vanadium-bearing titanomagnetite, such as high energy consumption and low productivity; simer quality is also very poor for its low tumble strength and high reduction deg- radation. Sinter productivity and quality are dominated by bed permeability and mineralogy structure, which are highly influenced by the thermal state of sintering bed, so the sintering process of titanomagnetite is researched by bed dissection in this work. Temperature evolution curves of sinter materials were measured, and the results show that melting duration, peak temperature duration and sintering temperature of different layers differ greatly from each other; flame front speed and vertical sintering speed of bed lower region are much smaller than those of bed up- per region. Simultaneously, sinter samples were collected from different layers, and their mineralogy characteristics are analyzed; sinters from bed lower region have poor mineralogy structure, and the amounts of perovskite and dieM- cium silicate increase intensively, which are bad for sinter strength and reduction degradation property. Measures are proposed to improve the quality and productivity of titanomagnetite sinter.展开更多
For the bell-less top blast furnace, when particles move along the chute, the particlesr motion direction and the frictional force acting on them will change due to the chute rotation, which consequently influences th...For the bell-less top blast furnace, when particles move along the chute, the particlesr motion direction and the frictional force acting on them will change due to the chute rotation, which consequently influences the velocity at the tip of chute, changes the burden flow width and impact point, and finally affects the stock profile and gas f[ow distribution. So the influence of chute rotation needs to be considered when calculating the burden trajectory with a mathematical model. The mathematical model was established to analyze the influence of Coriolis force on particle velocity at chute tip as well as height and width of burden flow in chute, and to summarize the effect of Coriolis force on burden distribution, thereby making the calculation result more accurate.展开更多
Reasonable control on CRI（coke reaction index）is one of the key factors for BF（blast furnace）low-carbon smelting.However,there are contrary opinions.One is increasing CRI to improve reaction efficiency in BF and t...Reasonable control on CRI（coke reaction index）is one of the key factors for BF（blast furnace）low-carbon smelting.However,there are contrary opinions.One is increasing CRI to improve reaction efficiency in BF and the other is decreasing CRI to suppress coke degradation in furnace.Different methods are adopted to realize effective catalysis（increasing CRI）and passivation（decreasing CRI）of coke.Simulation tests of coke in BF lumpy zone under gradual temperature rising have been done.Effect of CRI on gas composition,ore reduction,burden column permeability and heat reserve zone′s temperature under non-isothermal condition are studied.Then combined with iron making calculations,a novel BF operation suggestion is proposed as coke nut with small size be catalyzed and mixed with ore while skeletal coke with large size be passivated and separately charged into BF.展开更多
基金Item Sponsored by National Natural Science Foundation of China (60472095)
文摘One of the bottlenecks of the blast furnace （BF） campaign is the life length of hearth bottom. The basic reason for the erosion of hearth bottom is its direct contact with hot metal. According to the theory of heat transfer, models of BF hearth bottom are built based on the actual examples using software and VC language, and the calculated results are in good agreement with the data of BF dissection after blowing out. The temperature distribution and the capability of the resistance to erosion for different structures of hearth bottom are analyzed, especially the two prevalent kinds of hearth bottom arrangements called ＂the method of heat transfer＂ for all-carbon brick bottom and ＂the method of heat isolation＂ for ceramic synthetic hearth bottom. Features of the two kinds of hearth bottoms are analyzed. Also the different ways of protecting the hearth bottom are clarified, according to some actual examples. After that, the same essence of prolonging life, and the fact that the existence of a ＂protective skull＂ with low thermal conductivity between the hot metal and brick layers is of utmost importance are shown.
基金Item Sponsored by National Natural Science Foundation of China(61271303)
文摘Steel plate cold common （SPCC） is a Al-killed steel with Ca-treatment. The control of Al2O3 inclusion into low melting point liquid region is beneficial for inclusion removal, cast-ability promotion and defects reduction during rolling. Thus it is essential to understand steel-inclusion equilibrium since inclusion composition is determined by composition of liquid steel directly through steel-inclusion reaction. Thermodynamic calculation software FactSage is performed to understand how to control inclusion composition during ladle furnace （LF） refining, and industrial trials are carried out to verify calculated results. Firstly, target region for controlling CaO-Al2O3-MgO ternary inclusion is analyzed on the basis of the ternary phase diagram and the relationship between activities related to pure solid and activities related to pure liquid was fixed by thermodynamic analysis in order to obtain reliable activities for components of inclusions in the target region by FactSage. In addition, inclusions in steel samples are detected by scanning electron microscopy （SEM） combined with energy dispersive spectroscopy （EDS）. It is found that most of Al2O3 inclusions are modified into lower melting point region but a number of them are still located in high melting point region at the end of LF refining after Ca-treatment. Moreover, the composition of liquid steel equilibrating with liquid CaO-Al2O3-MgO inclusion is obtained by steel-inclusion equilibrium calculation when w[Al]s is approximating 0.03% as： a[O] is 1.0×10-6 to 4.0×10-6, w[Ca] is 20×10-6 to 50×10-6 and w[Mg] is 0.1×10-6 to 3.0×10-6. At last, stability diagrams of various calcium aluminates and CaS are established and they show that liquid calcium aluminate inclusions form when w[Ca] is more than 20×10-6, but CaS precipitation is difficult to prevent because sufficiently low w[S] （〈0.003%） is required.
基金Item Sponsored by National Natural Science Foundation of China(60872147)
文摘Many problems appear in the sintering process of vanadium-bearing titanomagnetite, such as high energy consumption and low productivity; simer quality is also very poor for its low tumble strength and high reduction deg- radation. Sinter productivity and quality are dominated by bed permeability and mineralogy structure, which are highly influenced by the thermal state of sintering bed, so the sintering process of titanomagnetite is researched by bed dissection in this work. Temperature evolution curves of sinter materials were measured, and the results show that melting duration, peak temperature duration and sintering temperature of different layers differ greatly from each other; flame front speed and vertical sintering speed of bed lower region are much smaller than those of bed up- per region. Simultaneously, sinter samples were collected from different layers, and their mineralogy characteristics are analyzed; sinters from bed lower region have poor mineralogy structure, and the amounts of perovskite and dieM- cium silicate increase intensively, which are bad for sinter strength and reduction degradation property. Measures are proposed to improve the quality and productivity of titanomagnetite sinter.
基金Item Sponsored by National Natural Science Foundation of China(60872147)
文摘For the bell-less top blast furnace, when particles move along the chute, the particlesr motion direction and the frictional force acting on them will change due to the chute rotation, which consequently influences the velocity at the tip of chute, changes the burden flow width and impact point, and finally affects the stock profile and gas f[ow distribution. So the influence of chute rotation needs to be considered when calculating the burden trajectory with a mathematical model. The mathematical model was established to analyze the influence of Coriolis force on particle velocity at chute tip as well as height and width of burden flow in chute, and to summarize the effect of Coriolis force on burden distribution, thereby making the calculation result more accurate.
基金Sponsored by National Natural Science Foundation of China(61271303)Fundamental Research Funds for CentralUniversities of China(FRF-TP-12-029A)
文摘Reasonable control on CRI（coke reaction index）is one of the key factors for BF（blast furnace）low-carbon smelting.However,there are contrary opinions.One is increasing CRI to improve reaction efficiency in BF and the other is decreasing CRI to suppress coke degradation in furnace.Different methods are adopted to realize effective catalysis（increasing CRI）and passivation（decreasing CRI）of coke.Simulation tests of coke in BF lumpy zone under gradual temperature rising have been done.Effect of CRI on gas composition,ore reduction,burden column permeability and heat reserve zone′s temperature under non-isothermal condition are studied.Then combined with iron making calculations,a novel BF operation suggestion is proposed as coke nut with small size be catalyzed and mixed with ore while skeletal coke with large size be passivated and separately charged into BF.
