A mathematical model was established to describe the direct reduction of pellets in a rotary hearth furnace (RHF). In the model, heat transfer, mass transfer, and gas-solid chemical reactions were taken into account...A mathematical model was established to describe the direct reduction of pellets in a rotary hearth furnace (RHF). In the model, heat transfer, mass transfer, and gas-solid chemical reactions were taken into account. The behaviors of iron metallization and dezincification were analyzed by the numerical method, which was validated by experimental data of the direct reduction of pellets in a Si-Mo furnace. The simulation results show that if the production targets of iron metallization and dezincification are up to 80% and 90%, respectively, the furnace temperature for high-temperature sections must be set higher than 1300~ C. Moreover, an undersupply of secondary air by 20% will lead to a decline in iron metallization rate of discharged pellets by 10% and a decrease in dezincing rate by 13%. In addition, if the residence time of pellets in the furnace is over 20 min, its further extension will hardly lead to an obvious increase in production indexes under the same furnace temperature curve.展开更多
The co-reduction roasting and grinding-magnetic separation of seaside titanomagnetite and blast furnace dust was investigated with and without fluorite addition at a reduction roasting temperature of 1250°C for 6...The co-reduction roasting and grinding-magnetic separation of seaside titanomagnetite and blast furnace dust was investigated with and without fluorite addition at a reduction roasting temperature of 1250°C for 60 min, a grinding fineness of-43 μm accounting for 69.02 wt% of the total, and a low-intensity magnetic field strength of 151 kA/m. The mineral composition, microstructure, and state of the roasted products were analyzed, and the concentrations of CO and CO_2 were analyzed in the co-reduction roasting. Better results were achieved with a small fluorite dosage(≤4 wt%) in the process of co-reduction. In addition, F^- was found to reduce the melting point and viscosity of the slag phase because of the high content of aluminate and silicate minerals in the blast furnace dust. The low moisture content of the blast furnace dust and calcic minerals inhibited the hydrolysis of CaF_2 and the loss of F^-. Compared with the blast furnace dust from Chengdeng, the blast furnace dusts from Jiugang and Jinxin inhibited the diffusion of F-when used as reducing agents, leading to weaker effects of fluorite.展开更多
Three-dimensional model of chemical vapor deposition reaction in polysilicon reduction furnace was established by considering mass, momentum and energy transfer simultaneously. Then, CFD software was used to simulate ...Three-dimensional model of chemical vapor deposition reaction in polysilicon reduction furnace was established by considering mass, momentum and energy transfer simultaneously. Then, CFD software was used to simulate the flow, heat transfer and chemical reaction process in reduction furnace and to analyze the change law of deposition characteristic along with the H_2 mole fraction, silicon rod height and silicon rod diameter. The results show that with the increase of H_2 mole fraction, silicon growth rate increases firstly and then decreases. On the contrary, SiHCl_3 conversion rate and unit energy consumption decrease firstly and then increase. Silicon production rate increases constantly. The optimal H_2 mole fraction is 0.8-0.85. With the growth of silicon rod height, Si HCl3 conversion rate, silicon production rate and silicon growth rate increase, while unit energy consumption decreases. In terms of chemical reaction, the higher the silicon rod is, the better the performance is. In the view of the top-heavy situation, the actual silicon rod height is limited to be below 3 m. With the increase of silicon rod diameter, silicon growth rate decreases firstly and then increases. Besides, SiHCl_3 conversion rate and silicon production rate increase, while unit energy consumption first decreases sharply, then becomes steady. In practice, the bigger silicon rod diameter is more suitable. The optimal silicon rod diameter must be over 120 mm.展开更多
A study was carried out on the formation of Ti(C,N) during smelting vanadium-bearing titanomagnetite in blast furnace and the influence of MnO content on reduction of TiO_2 in the slag containing high titania. The red...A study was carried out on the formation of Ti(C,N) during smelting vanadium-bearing titanomagnetite in blast furnace and the influence of MnO content on reduction of TiO_2 in the slag containing high titania. The reduction of TiO_2 is restricted by MnOpredominantly at the slag-metal interface and no more at the slag-coke one. The formation of Ti(C,N) is remarkably restricted by MnO in the slag when the MnO content is about 4% and the basicity from 0.6 to 1.2 in the slag. MnO may also retards the reduction of SiO_2 and accelerates the desulphidation under certain condition.展开更多
This paper introduces both laboratory experi- ment and equilibrium calculations concerned with the Si reduction and reoxidation.The results give evidence that the Si transport in different directions just exists in th...This paper introduces both laboratory experi- ment and equilibrium calculations concerned with the Si reduction and reoxidation.The results give evidence that the Si transport in different directions just exists in the furnace hearth synchronistically, by which the desulphurization is also affected.The problems noticed for smelting tow Si pig iron are given.展开更多
The structural changes and reduction degree of chromite ore in blast furnace were studied by optical micrograph analysis,scanning electron microscope(SEM)and energy dispersive X-ray analysis(EDXA).The smelting reducti...The structural changes and reduction degree of chromite ore in blast furnace were studied by optical micrograph analysis,scanning electron microscope(SEM)and energy dispersive X-ray analysis(EDXA).The smelting reduction mechanism of chromite in blast furnace was primarily discussed.展开更多
Ore-coke mixed charging is a potential technique for optimizing the charging pattern. Recently, the charging of small-sized coke( nut coke) with the ferrous burden layer has been applied to reduce raw material usage...Ore-coke mixed charging is a potential technique for optimizing the charging pattern. Recently, the charging of small-sized coke( nut coke) with the ferrous burden layer has been applied to reduce raw material usage and decrease costs. Various studies indicate that mixing nut coke with ferrous burden can enhance the reduction kinetics,improve the softening and melting properties, and have a positive effect on the permeability. Although mixed charging, especially the addition of nut coke to the burden layer, has been used in the industry for various reasons ,the mechanisms and side effects for using nut coke are not well understood, and the mixing ratio remains limited in actual blast furnace operation. High-temperature experimental studies were conducted to increase the understanding of the complex process of reduction, softening and melting properties, and permeability in a blast furnace when mixing nut coke with an ore layer. The effect of the nut coke mixing ratio and nut coke size was investigated under various reducing conditions. To describe the reduction processes of burden materials, numerous experiments were interrupted at different stages of the reduction, and the collected materials were examined by using image analysis. The reduction degree of mixed charging(iron ore mixing with nut coke) was improved when using nut coke at the temperatures of 800 ℃ and above. The reaction rate of ore-nut coke mixed charging was higher than that of standard charging without the use of nut coke.展开更多
The strong global demand for iron and steel has necessitated the utilization of various low grade iron ores, which are not suitable for direct utilization in ironmaking processes. The low grade iron ores cannot be dre...The strong global demand for iron and steel has necessitated the utilization of various low grade iron ores, which are not suitable for direct utilization in ironmaking processes. The low grade iron ores cannot be dressed effectively using the traditional mineral processing methods because of complicated min-eral compositions. The main problem associated with exploiting these deposits is the dissemination of fine silicate minerals and the high level of phosphorus content due to the poor liberation of iron minerals from the gangues. The pre-sent manuscript is aimed to investigate reduction properties of iron ores rich in phosphorous in order to study the suitability of using these ores in iron blast furnace. Representative technological samples of iron ore are collected from Eastern South Aswan iron ore mine in Egypt. The principal gangue contents are SiO2 7.76%, and P2O5 1.13%. Iron and phosphorus exist in the form of hematite 78% and apatite respectively. The ore was fired at 1000°C for 3 hours. The green and fired samples were isothermally reduced at conditions which closely represent the theoretical reduction conditions in different zones of blast furnace. The influence of reduction conditions on the reduction behaviour and the morphology of the reduced samples were investigated. After reduction apatite is changed to Calcium phosphate beside fayalite and quartz. The reduction rate of fired samples is greater than that for the green ones and that was confirmed by morphological examination. At cohesive zone condition, the effect of firing on reduction characteristics cannot be distinguished.展开更多
The reduction process of MgO-fluxed pellets was investigated and compared with traditional acidic pellets in this paper. Based on the piston flow concept and experimental data, a kinetic model fitting for the gas-soli...The reduction process of MgO-fluxed pellets was investigated and compared with traditional acidic pellets in this paper. Based on the piston flow concept and experimental data, a kinetic model fitting for the gas-solid phase reduction of pellets in tubular reactors (blast furnace, BF) was built up, and the equations of reduction reaction rate were given for pellets. A series of reduction experiments of pellets were carried out to verify the model. As a result, the experimental data and calculated result were fitted well. Therefore, this model can well describe the gas-solid phase reduction process and calculate the reduction reaction rate of pellets. Besides, it can give a better explanation that the reduction reaction rate (reducibility) of MgO-fluxed pellets is better than that of traditional acidic pellets in BF.展开更多
Direct reduction of dust composite pellets containing zinc and iron was examined by simulating the conditions of actual production process of a rotary hearth furnace (RHF) in laboratory. A mathematical model was con...Direct reduction of dust composite pellets containing zinc and iron was examined by simulating the conditions of actual production process of a rotary hearth furnace (RHF) in laboratory. A mathematical model was constructed to study the reduction kinetics of iron oxides and ZnO in the dust composite pellets. It was validated by comparing the calculated values with experimental results. The effects of furnace temperature, pellet radius, and pellet porosity on the reduction were investigated by the model. It is shown that furnace temperature has obvious influence on both of the reduction of iron oxides and ZnO, but the influence of pellet radius and porosity is much smaller. Model calculations suggest that both of the reduction of iron oxides and ZnO are under mixed control with interface reactions and Boudouard reaction in the early stage, but only with interface reactions in the later stage.展开更多
Based on the laboratory experiment of reducing iron ore-coal pellet in oxidizing atmosphere,a new self-heating reduction method of iron ore-coal pellet in the cocurrent shaft furnace(CSF) has been developed.In this pr...Based on the laboratory experiment of reducing iron ore-coal pellet in oxidizing atmosphere,a new self-heating reduction method of iron ore-coal pellet in the cocurrent shaft furnace(CSF) has been developed.In this process,the pellets and preheated oxygen-enriched air enter the shaft furnace through its top and descend cocurrently in the furnace.Most of the heat required for rising temperature and endothermic reduction of descending pellets is provided by the way that the descending air burns the volatile from pellets and CO from the reduction of iron oxide in pellets.The reduced pellets and high temperature gas are discharged from the lower part.The sensible heat and chemical energy of the off-gas are used to heat the oxygen-enriched air in stove.This process is applicable to the direct reduction of iron pellets and prereduction of iron pellets in smelting reduction with iron bath.展开更多
The feasibility of reducing Cr(VI)from the aqueous solution by sulfuric acid-modified titanium-bearing blast furnace slag(SATBBFS)as a photocatalyst was investigated.The photocatalysts were examined by X-ray diffracti...The feasibility of reducing Cr(VI)from the aqueous solution by sulfuric acid-modified titanium-bearing blast furnace slag(SATBBFS)as a photocatalyst was investigated.The photocatalysts were examined by X-ray diffraction(XRD),UV-vis diffuse reflectance spectra,thermogravimetric analysis(TG)and Fourier transform infrared spectroscopy(FTIR).The photocatalytic activities of the different catalysts were evaluated by the photocatalytic reduction of Cr(VI)under UV-vis light irradiation.The results show that the photocatalytic activities of SATBBFS catalysts are strongly dependent on CaTiO3-to-TiO2 mass ratio,adsorption capacity and surface acidity,and SATBBFS calcined at 400°C shows a higher photocatalytic activity compared with other catalysts.展开更多
It is of great importance to elucidate reduction swelling behaviors and reaction mechanism of oxidized pellet in hydrogen-enriched atmosphere under coke oven gas injection. In this work, the effects of hydrogen concen...It is of great importance to elucidate reduction swelling behaviors and reaction mechanism of oxidized pellet in hydrogen-enriched atmosphere under coke oven gas injection. In this work, the effects of hydrogen concentration in N_2-CO-H_2 atmosphere with unchanged CO content on reduction swelling behaviors of oxidized pellet at 1173 K were studied, to clarify the mechanism of hydrogen-enriched reduction and exclude the influences of CO. Then, the reduction swelling behaviors of oxidized pellet at 1173 K in actual atmosphere under coke oven gas(COG) injection, got from the simulation results of multi-fluid blast furnace model, were investigated. The results show that with the concentration of hydrogen increasing in N_2-CO-H_2 gas from 2% to 18%, the reduction swelling index of pellet decreases from 10.12% to 5.57% while the reduction ratio of pellet increases obviously from 39.85% to 69.58%. In addition, with COG injection rate increasing from 0 to 152.34 m^3/t, the reduction swelling index of pellet decreases slightly from 10.71% to 9.54% while the reduction ratio of pellet is increased from 31.57% to 36.39%. The microstructures of pellet are transformed from the platy structure to the flocculent structure.展开更多
Clean Production is the best method for iron-steel making industry to eliminate pollution thoroughly. In order to achieve this object, smelting reduction technology should play the key role. Furthermore, process integ...Clean Production is the best method for iron-steel making industry to eliminate pollution thoroughly. In order to achieve this object, smelting reduction technology should play the key role. Furthermore, process integration method can be used to solve the problem of residual gas utilization by integrating smelting reduction process with direct reduced iron unit, gasoline, methanol or dimethyl ether synthesis unit, etc. A new smelting reduction process has been proposed which can be constructed on the present plant site. Since this process can directly treat the lump coal and iron ore fines, it reduces st6ps necessary in traditional blast furnace process and Corex smelting reduction process.展开更多
This study has been performed to investigate the different parameters affecting on the production of high carbon ferromanganese in closed submerged arc furnace. The analysis of industrial data revealed that using mang...This study has been performed to investigate the different parameters affecting on the production of high carbon ferromanganese in closed submerged arc furnace. The analysis of industrial data revealed that using manganese ores with low Mn/Fe ratio necessitates higher amount of Mn-sinter in the charge. Using Mn-blend with higher Mn/Fe ratio reduces the coke consumption and this leads to reducing the electrodes consumption. The recovery of Mn ranges between 70 and 80 %. Much higher basic slag has slight effect on Mn- recovery. However, as slag basicity increases, the MnO- content of slag decreases. The manganese content of produced HCFeMn depends mainly on Mn/Fe ratio of Mn-blend. For obtaining HCFeMn alloy containing minimum 75%Mn, it is necessary to use Mn-blend with Mn/Fe ratio of higher than 6. A model for determination of the amount and composition of off-gases has been derived based on the chemical composition and material balance of the input raw materials and the produced alloy and slag. By using this model, the amount of off-gases was found to increase by increasing both Mn-blend and coke consumption.展开更多
This paper presents the fundamentals of thermal pyrolysis and discusses the modern ethylene furnace technology and its design trends. Technip’s proprietary SPYRO? program is discussed for prediction of hydrocarbon cr...This paper presents the fundamentals of thermal pyrolysis and discusses the modern ethylene furnace technology and its design trends. Technip’s proprietary SPYRO? program is discussed for prediction of hydrocarbon cracking.展开更多
The effect of H_2 gas content on the reduction of Panzhihua titanomagnetite concentrate pellets by carbon monoxide was investigated by isothermal reduction experiment using CO-N_2-H_2 gas mixtures in a vertical electr...The effect of H_2 gas content on the reduction of Panzhihua titanomagnetite concentrate pellets by carbon monoxide was investigated by isothermal reduction experiment using CO-N_2-H_2 gas mixtures in a vertical electric resistance furnace.The morphology and phase transformation of reduced samples obtained were detected by scanning electron microscopy,energy disperse spectroscopy analysis and X-ray diffractometry respectively.The results show that increasing H_2 content will enhance the initial stage of reduction rate apparently.There are two reasons responsible for this effect,one is that H_2 accelerates the chemical reaction,and the other is that the addition of H_2 gas can improve the porosity of pellet intensively.It is noteworthy that this effect is more obvious when the reduction temperature reaches 1473 K with sticking phenomenon happening.There are no crystalline phases which can be found such as ulvospinle,ilmenite,ferrous-pseudobrookite and any titanium oxide except titanomagnetite(TTM).The reduction progress is suggested as follows:1) Fe_2O_3→Fe_3O_4→FeO→Fe;2) Fe_2TiO_5→Fe_2TiO_4+Fe_3O_4→TTM.Element Al migrates and gets enriched in high titanium content iron ores,and eventually Al to Ti molar ratio is 1:3.Al is likely to dissolve in titanium iron oxides to form a kind of composite iron compound,which results in the restrain of reduction.展开更多
基金financially supported by the National Key Basic Research and Development Program of China(No. 2012CB720405)
文摘A mathematical model was established to describe the direct reduction of pellets in a rotary hearth furnace (RHF). In the model, heat transfer, mass transfer, and gas-solid chemical reactions were taken into account. The behaviors of iron metallization and dezincification were analyzed by the numerical method, which was validated by experimental data of the direct reduction of pellets in a Si-Mo furnace. The simulation results show that if the production targets of iron metallization and dezincification are up to 80% and 90%, respectively, the furnace temperature for high-temperature sections must be set higher than 1300~ C. Moreover, an undersupply of secondary air by 20% will lead to a decline in iron metallization rate of discharged pellets by 10% and a decrease in dezincing rate by 13%. In addition, if the residence time of pellets in the furnace is over 20 min, its further extension will hardly lead to an obvious increase in production indexes under the same furnace temperature curve.
基金financially supported by the National Natural Science Foundation of China (No. 51474018)
文摘The co-reduction roasting and grinding-magnetic separation of seaside titanomagnetite and blast furnace dust was investigated with and without fluorite addition at a reduction roasting temperature of 1250°C for 60 min, a grinding fineness of-43 μm accounting for 69.02 wt% of the total, and a low-intensity magnetic field strength of 151 kA/m. The mineral composition, microstructure, and state of the roasted products were analyzed, and the concentrations of CO and CO_2 were analyzed in the co-reduction roasting. Better results were achieved with a small fluorite dosage(≤4 wt%) in the process of co-reduction. In addition, F^- was found to reduce the melting point and viscosity of the slag phase because of the high content of aluminate and silicate minerals in the blast furnace dust. The low moisture content of the blast furnace dust and calcic minerals inhibited the hydrolysis of CaF_2 and the loss of F^-. Compared with the blast furnace dust from Chengdeng, the blast furnace dusts from Jiugang and Jinxin inhibited the diffusion of F-when used as reducing agents, leading to weaker effects of fluorite.
基金Project(12C0379) supported by Scientific Research Fund of Hunan Province,China
文摘Three-dimensional model of chemical vapor deposition reaction in polysilicon reduction furnace was established by considering mass, momentum and energy transfer simultaneously. Then, CFD software was used to simulate the flow, heat transfer and chemical reaction process in reduction furnace and to analyze the change law of deposition characteristic along with the H_2 mole fraction, silicon rod height and silicon rod diameter. The results show that with the increase of H_2 mole fraction, silicon growth rate increases firstly and then decreases. On the contrary, SiHCl_3 conversion rate and unit energy consumption decrease firstly and then increase. Silicon production rate increases constantly. The optimal H_2 mole fraction is 0.8-0.85. With the growth of silicon rod height, Si HCl3 conversion rate, silicon production rate and silicon growth rate increase, while unit energy consumption decreases. In terms of chemical reaction, the higher the silicon rod is, the better the performance is. In the view of the top-heavy situation, the actual silicon rod height is limited to be below 3 m. With the increase of silicon rod diameter, silicon growth rate decreases firstly and then increases. Besides, SiHCl_3 conversion rate and silicon production rate increase, while unit energy consumption first decreases sharply, then becomes steady. In practice, the bigger silicon rod diameter is more suitable. The optimal silicon rod diameter must be over 120 mm.
文摘A study was carried out on the formation of Ti(C,N) during smelting vanadium-bearing titanomagnetite in blast furnace and the influence of MnO content on reduction of TiO_2 in the slag containing high titania. The reduction of TiO_2 is restricted by MnOpredominantly at the slag-metal interface and no more at the slag-coke one. The formation of Ti(C,N) is remarkably restricted by MnO in the slag when the MnO content is about 4% and the basicity from 0.6 to 1.2 in the slag. MnO may also retards the reduction of SiO_2 and accelerates the desulphidation under certain condition.
文摘This paper introduces both laboratory experi- ment and equilibrium calculations concerned with the Si reduction and reoxidation.The results give evidence that the Si transport in different directions just exists in the furnace hearth synchronistically, by which the desulphurization is also affected.The problems noticed for smelting tow Si pig iron are given.
基金Item Sponsored by National Natural Science Foundation of China(51074036)
文摘The structural changes and reduction degree of chromite ore in blast furnace were studied by optical micrograph analysis,scanning electron microscope(SEM)and energy dispersive X-ray analysis(EDXA).The smelting reduction mechanism of chromite in blast furnace was primarily discussed.
文摘Ore-coke mixed charging is a potential technique for optimizing the charging pattern. Recently, the charging of small-sized coke( nut coke) with the ferrous burden layer has been applied to reduce raw material usage and decrease costs. Various studies indicate that mixing nut coke with ferrous burden can enhance the reduction kinetics,improve the softening and melting properties, and have a positive effect on the permeability. Although mixed charging, especially the addition of nut coke to the burden layer, has been used in the industry for various reasons ,the mechanisms and side effects for using nut coke are not well understood, and the mixing ratio remains limited in actual blast furnace operation. High-temperature experimental studies were conducted to increase the understanding of the complex process of reduction, softening and melting properties, and permeability in a blast furnace when mixing nut coke with an ore layer. The effect of the nut coke mixing ratio and nut coke size was investigated under various reducing conditions. To describe the reduction processes of burden materials, numerous experiments were interrupted at different stages of the reduction, and the collected materials were examined by using image analysis. The reduction degree of mixed charging(iron ore mixing with nut coke) was improved when using nut coke at the temperatures of 800 ℃ and above. The reaction rate of ore-nut coke mixed charging was higher than that of standard charging without the use of nut coke.
文摘The strong global demand for iron and steel has necessitated the utilization of various low grade iron ores, which are not suitable for direct utilization in ironmaking processes. The low grade iron ores cannot be dressed effectively using the traditional mineral processing methods because of complicated min-eral compositions. The main problem associated with exploiting these deposits is the dissemination of fine silicate minerals and the high level of phosphorus content due to the poor liberation of iron minerals from the gangues. The pre-sent manuscript is aimed to investigate reduction properties of iron ores rich in phosphorous in order to study the suitability of using these ores in iron blast furnace. Representative technological samples of iron ore are collected from Eastern South Aswan iron ore mine in Egypt. The principal gangue contents are SiO2 7.76%, and P2O5 1.13%. Iron and phosphorus exist in the form of hematite 78% and apatite respectively. The ore was fired at 1000°C for 3 hours. The green and fired samples were isothermally reduced at conditions which closely represent the theoretical reduction conditions in different zones of blast furnace. The influence of reduction conditions on the reduction behaviour and the morphology of the reduced samples were investigated. After reduction apatite is changed to Calcium phosphate beside fayalite and quartz. The reduction rate of fired samples is greater than that for the green ones and that was confirmed by morphological examination. At cohesive zone condition, the effect of firing on reduction characteristics cannot be distinguished.
基金financially supported by the Natural Science Foundation of China(Nos.51374061 and 51074040)
文摘The reduction process of MgO-fluxed pellets was investigated and compared with traditional acidic pellets in this paper. Based on the piston flow concept and experimental data, a kinetic model fitting for the gas-solid phase reduction of pellets in tubular reactors (blast furnace, BF) was built up, and the equations of reduction reaction rate were given for pellets. A series of reduction experiments of pellets were carried out to verify the model. As a result, the experimental data and calculated result were fitted well. Therefore, this model can well describe the gas-solid phase reduction process and calculate the reduction reaction rate of pellets. Besides, it can give a better explanation that the reduction reaction rate (reducibility) of MgO-fluxed pellets is better than that of traditional acidic pellets in BF.
基金financially supported by the National Basic Research Program of China (No. 2012CB720401)the National Key Technology Research and Development Program of China (No. 2011BAC01B02)
文摘Direct reduction of dust composite pellets containing zinc and iron was examined by simulating the conditions of actual production process of a rotary hearth furnace (RHF) in laboratory. A mathematical model was constructed to study the reduction kinetics of iron oxides and ZnO in the dust composite pellets. It was validated by comparing the calculated values with experimental results. The effects of furnace temperature, pellet radius, and pellet porosity on the reduction were investigated by the model. It is shown that furnace temperature has obvious influence on both of the reduction of iron oxides and ZnO, but the influence of pellet radius and porosity is much smaller. Model calculations suggest that both of the reduction of iron oxides and ZnO are under mixed control with interface reactions and Boudouard reaction in the early stage, but only with interface reactions in the later stage.
基金Project supported by the National Foundation of Nature Science of China
文摘Based on the laboratory experiment of reducing iron ore-coal pellet in oxidizing atmosphere,a new self-heating reduction method of iron ore-coal pellet in the cocurrent shaft furnace(CSF) has been developed.In this process,the pellets and preheated oxygen-enriched air enter the shaft furnace through its top and descend cocurrently in the furnace.Most of the heat required for rising temperature and endothermic reduction of descending pellets is provided by the way that the descending air burns the volatile from pellets and CO from the reduction of iron oxide in pellets.The reduced pellets and high temperature gas are discharged from the lower part.The sensible heat and chemical energy of the off-gas are used to heat the oxygen-enriched air in stove.This process is applicable to the direct reduction of iron pellets and prereduction of iron pellets in smelting reduction with iron bath.
基金Project(N090423003)supported by the Basic Scientific Research Costs of Central Colleges of ChinaProject(2007CB613504)supported by the National Basic Research Program of ChinaProject(307009)supported by the Foundation for Key Program of Ministry of Education,China
文摘The feasibility of reducing Cr(VI)from the aqueous solution by sulfuric acid-modified titanium-bearing blast furnace slag(SATBBFS)as a photocatalyst was investigated.The photocatalysts were examined by X-ray diffraction(XRD),UV-vis diffuse reflectance spectra,thermogravimetric analysis(TG)and Fourier transform infrared spectroscopy(FTIR).The photocatalytic activities of the different catalysts were evaluated by the photocatalytic reduction of Cr(VI)under UV-vis light irradiation.The results show that the photocatalytic activities of SATBBFS catalysts are strongly dependent on CaTiO3-to-TiO2 mass ratio,adsorption capacity and surface acidity,and SATBBFS calcined at 400°C shows a higher photocatalytic activity compared with other catalysts.
基金Project(51404005)supported by the National Natural Science Foundation of China
文摘It is of great importance to elucidate reduction swelling behaviors and reaction mechanism of oxidized pellet in hydrogen-enriched atmosphere under coke oven gas injection. In this work, the effects of hydrogen concentration in N_2-CO-H_2 atmosphere with unchanged CO content on reduction swelling behaviors of oxidized pellet at 1173 K were studied, to clarify the mechanism of hydrogen-enriched reduction and exclude the influences of CO. Then, the reduction swelling behaviors of oxidized pellet at 1173 K in actual atmosphere under coke oven gas(COG) injection, got from the simulation results of multi-fluid blast furnace model, were investigated. The results show that with the concentration of hydrogen increasing in N_2-CO-H_2 gas from 2% to 18%, the reduction swelling index of pellet decreases from 10.12% to 5.57% while the reduction ratio of pellet increases obviously from 39.85% to 69.58%. In addition, with COG injection rate increasing from 0 to 152.34 m^3/t, the reduction swelling index of pellet decreases slightly from 10.71% to 9.54% while the reduction ratio of pellet is increased from 31.57% to 36.39%. The microstructures of pellet are transformed from the platy structure to the flocculent structure.
文摘Clean Production is the best method for iron-steel making industry to eliminate pollution thoroughly. In order to achieve this object, smelting reduction technology should play the key role. Furthermore, process integration method can be used to solve the problem of residual gas utilization by integrating smelting reduction process with direct reduced iron unit, gasoline, methanol or dimethyl ether synthesis unit, etc. A new smelting reduction process has been proposed which can be constructed on the present plant site. Since this process can directly treat the lump coal and iron ore fines, it reduces st6ps necessary in traditional blast furnace process and Corex smelting reduction process.
文摘This study has been performed to investigate the different parameters affecting on the production of high carbon ferromanganese in closed submerged arc furnace. The analysis of industrial data revealed that using manganese ores with low Mn/Fe ratio necessitates higher amount of Mn-sinter in the charge. Using Mn-blend with higher Mn/Fe ratio reduces the coke consumption and this leads to reducing the electrodes consumption. The recovery of Mn ranges between 70 and 80 %. Much higher basic slag has slight effect on Mn- recovery. However, as slag basicity increases, the MnO- content of slag decreases. The manganese content of produced HCFeMn depends mainly on Mn/Fe ratio of Mn-blend. For obtaining HCFeMn alloy containing minimum 75%Mn, it is necessary to use Mn-blend with Mn/Fe ratio of higher than 6. A model for determination of the amount and composition of off-gases has been derived based on the chemical composition and material balance of the input raw materials and the produced alloy and slag. By using this model, the amount of off-gases was found to increase by increasing both Mn-blend and coke consumption.
文摘This paper presents the fundamentals of thermal pyrolysis and discusses the modern ethylene furnace technology and its design trends. Technip’s proprietary SPYRO? program is discussed for prediction of hydrocarbon cracking.
基金Project (51134008) supported by the National Natural Science Foundation of ChinaProject (2012CB720401) supported by the National Basic Research Program of China
文摘The effect of H_2 gas content on the reduction of Panzhihua titanomagnetite concentrate pellets by carbon monoxide was investigated by isothermal reduction experiment using CO-N_2-H_2 gas mixtures in a vertical electric resistance furnace.The morphology and phase transformation of reduced samples obtained were detected by scanning electron microscopy,energy disperse spectroscopy analysis and X-ray diffractometry respectively.The results show that increasing H_2 content will enhance the initial stage of reduction rate apparently.There are two reasons responsible for this effect,one is that H_2 accelerates the chemical reaction,and the other is that the addition of H_2 gas can improve the porosity of pellet intensively.It is noteworthy that this effect is more obvious when the reduction temperature reaches 1473 K with sticking phenomenon happening.There are no crystalline phases which can be found such as ulvospinle,ilmenite,ferrous-pseudobrookite and any titanium oxide except titanomagnetite(TTM).The reduction progress is suggested as follows:1) Fe_2O_3→Fe_3O_4→FeO→Fe;2) Fe_2TiO_5→Fe_2TiO_4+Fe_3O_4→TTM.Element Al migrates and gets enriched in high titanium content iron ores,and eventually Al to Ti molar ratio is 1:3.Al is likely to dissolve in titanium iron oxides to form a kind of composite iron compound,which results in the restrain of reduction.