The self-reforming of coke oven gas(COG)in a gas-based shaft furnace was investigated,employing metallized iron as a catalyst.Thermodynamic analyses,supported by FactSage 8.3 calculations and regression modeling,were ...The self-reforming of coke oven gas(COG)in a gas-based shaft furnace was investigated,employing metallized iron as a catalyst.Thermodynamic analyses,supported by FactSage 8.3 calculations and regression modeling,were used to investigate the effects of temperature(700–1100℃),CO_(2)(3%–10%),and H_(2)O(1%–9%)concentrations on CH_(4) conversion efficiency.Results indicate that CH_(4) conversion exceeds 90%at temperatures above 1000℃,with CO_(2) and H_(2)O concentrations at 9%and 5%,respectively.During the reforming process,introducing CO_(2) provides additional oxygen,facilitating the oxidation of CH_(4),while H_(2)O enhances H_(2) production through the steam reforming pathway.Experimental findings reveal a CH_(4) conversion of 85.83%with a H_(2)/CO ratio of 5.44 at 1050℃.In addition,an optimal H_(2)O concentration of 6%yields the highest CH_(4) conversion of 84.24%,while CO_(2) exhibits minimal effects on promoting the reforming process.Increasing the metallization rate of pellets from 43%to 92%significantly enhances CH_(4) reforming.This is mainly due to the fact that metallized iron is vital in promoting CH_(4) dissociation and improving syngas yield by providing active sites for the redox cycle of CO_(2) and H_(2)O.展开更多
With the depletion of high-quality iron ore resources,high-phosphorus oolitic hematite(HPOH)has attracted great attention due to its large reserve and relatively high iron content.However,HPOH is very difficult to be ...With the depletion of high-quality iron ore resources,high-phosphorus oolitic hematite(HPOH)has attracted great attention due to its large reserve and relatively high iron content.However,HPOH is very difficult to be used in ironmaking process due to its special structure.A two-step method of gas-based direct reduction and magnetic separation was thus proposed to recover iron and reduce phosphorus.The results showed that the powdery reduced iron produced contained 92.31%iron and 0.1%phosphorus,and the iron recovery was 92.65%under optimum reduction condition,which is suitable for following steelmaking.The apatite will be reduced under long reduction time and a large reducing gas flow rate,resulting in more phosphorus found in the metallic iron.Increasing the hydrogen–carbon ratio will inhibit the formation and growth of iron particles and prevent the breakage of oolitic structure.Careful adjustment of reduction temperature is recommended as it affects the oolitic structure and reduction.展开更多
A new method （gas-based separation plus melt separation） has been proposed to remove phosphorus of the high phosphorus iron ore which was 1.25 % of phosphorus content and 50. 0% of iron content. HSC chemistry packag...A new method （gas-based separation plus melt separation） has been proposed to remove phosphorus of the high phosphorus iron ore which was 1.25 % of phosphorus content and 50. 0% of iron content. HSC chemistry package and the coexistence theory of slag structure were adopted for theoretical analysis. The gas-based reduction was carried out using a fixed bed reactor and the ore sample of 80 g with an average particle size of 2 mm were reduced using CO or H2 at temperature of 1 073 K for 5 hours. 50 g of the reduced sample with 3.0% CaO as additive was then subjected to melt separation in an electric furnace at temperature of 1 873 K under Ar atmosphere. In each run, SEM, EDS, optical microscopic examination and chemical analysis of the reduced ore sample, the metal sample and the slag sample were conducted. Results of all gas-based reduction experiments showed that iron metallization ratios were some 65% and the phosphorus compounds in the ore remained unchanged. It was agreed well with the simula- tions except for the iron metallization rate being less than predicted value; this difference was attributed to kinetics. Results of melt separation experiments showed that P content in metal samples is 0.33% （metal sample from H2 reduction product） and 0.27% （metal sample from CO reduction product）. The phosphorus partition ratios of both cases were less than predicted values. Some P in the metal samples existed as slag inclusion was considered to be the reason for this discrepancy.展开更多
Numerous studies have focused on the reduction thermodynamics of ordinary iron ore;by contrast, the literature contains few thermodynamic studies on the gas-based reduction of vanadium titano-magnetite (VTM) in mixed ...Numerous studies have focused on the reduction thermodynamics of ordinary iron ore;by contrast, the literature contains few thermodynamic studies on the gas-based reduction of vanadium titano-magnetite (VTM) in mixed atmospheres of H2, CO, H2O, CO2, and N2. In this paper, thermodynamic studies on the reduction of oxidized VTM pellets were systematically conducted in an atmosphere of a C–H–O system as a reducing agent. The results indicate that VTM of an equivalent valence state is more difficult to reduce than ordinary iron ore. A reduction equilibrium diagram using the C–H–O system as a reducing agent was obtained;it clearly describes the reduction process. Experiments were performed to investigate the effects of the reduction temperature, the gas composition, and two types of iron ores on the reduction of oxidized VTM pellets. The results show that the final reduction degree increases with increasing reduction temperature, increasing molar ratio of H2/(H2 + CO), and decreasing H2O, CO2, and N2 contents. In addition, the reduction processes under various conditions are discussed. All of the results of the reduction experiments are consistent with those of theoretical thermodynamic analysis. This study is expected to provide valuable thermodynamic theory on the industrial applications of VTM.展开更多
Alastraet： The gas-based direct reduction of iron ore pellets was carried out by simulating the typical gas composition in coal gasification process, Midrex and HyMII processes. The influences of gas composition and ...Alastraet： The gas-based direct reduction of iron ore pellets was carried out by simulating the typical gas composition in coal gasification process, Midrex and HyMII processes. The influences of gas composition and temperature on reduction were studied. Results show that the increasing of HE proportion is helpful to improve the reduction rate. However, when ~o（H2）：~o（CO）〉1.6：1, changes of HE content have little influence on it. Appropriate reduction temperature is about 950 ℃, and higher temperature （1 000 ℃） may unfavorably slow the reduction rate. From the kinetics analysis at 950 ℃, the most part of reduction course is likely controlled by interfacial chemical reaction mechanism and in the final stage controlled by a combined effect of gaseous diffusion and interfacial chemical reaction mechanisms. From the utilizations study of different reducing gases at 950 ℃, the key step in reduction course is the 3rd stage （FeO→Fe）, and the utilization of reducing gas increases with the rise of HE proportion.展开更多
Hydrogen-based shaft furnace process is gaining more and more attention due to its low carbon emission, and the reduction behavior of iron bearing burdens significantly affects its operation. In this work, the effects...Hydrogen-based shaft furnace process is gaining more and more attention due to its low carbon emission, and the reduction behavior of iron bearing burdens significantly affects its operation. In this work, the effects of reduction degree, temperature, and atmosphere on the swelling behavior of pellet has been studied thoroughly under typical hydrogen metallurgy conditions. The results show that the pellets swelled rapidly in the early reduction stage, then reached a maximum reduction swelling index (RSI) at approximately 40%reduction degree. The crystalline transformation of the iron oxides during the reduction process was the main reason of pellets swelling. The RSI increased significantly with increasing temperature in the range of 850-1050℃, the maximum RSI increased from 6.66%to 25.0%in the gas composition of 100%H_(2). With the temperature increased, the pellets suffered more thermal stress resulting in an increase of the volume. The maximum RSI decreased from 19.78%to 17.35%with the volume proportion of H_(2) in the atmosphere increased from 55%to 100%at the temperature of 950℃.The metallic iron tended to precipitate in a lamellar structure rather than whiskers. Consequently, the inside of the pellets became regular, so the RSI decreased. Overall, controlling a reasonable temperature and increasing the H_(2) proportion is an effective way to decrease the RSI of pellets.展开更多
Hongge vanadium titanomagnetite（HVTM）pellets were reduced by H2-CO gas mixture for simulating the reduction processes of Midrex and HYL-III shaft furnaces.The influences of reduction temperature,ratio ofφ（H2）toφ...Hongge vanadium titanomagnetite（HVTM）pellets were reduced by H2-CO gas mixture for simulating the reduction processes of Midrex and HYL-III shaft furnaces.The influences of reduction temperature,ratio ofφ（H2）toφ（CO）,and pellet size on the reduction of HVTM pellets were evaluated in detail and the reduction reaction kinetics was investigated.The results show that both the reduction degree and reduction rate can be improved with increasing the reduction temperature and the H2 content as well as decreasing the pellet size.The rational reduction parameters are reduction temperature of 1050℃,ratio ofφ（H2）toφ（CO）of 2.5,and pellet diameter in the range of 8-11 mm.Under these conditions（pellet diameter of 11mm）,final reduction degree of 95.51% is achieved.The X-ray diffraction（XRD）pattern shows that the main phases of final reduced pellets under these conditions（pellet diameter of 11 mm）are reduced iron and rutile.The peak intensity of reduced iron increases obviously with the increase in the reduction temperature.Besides,relatively high reduction temperature promotes the migration and coarsening of metallic iron particles and improves the distribution of vanadium and chromium in the reduced iron,which is conducive to subsequent melting separation.At the early stage,the reduction process is controlled by interfacial chemical reaction and the apparent activation energy is 60.78kJ/mol.The reduction process is controlled by both interfacial chemical reaction and internal diffusion at the final stage,and the apparent activation energy is 30.54kJ/mol.展开更多
The influence of basicity on the metallurgical performances and reduction characteristics of fired super high-grade magnetite pellets under the simulated shaft furnace gas conditions was investigated.The fired pellets...The influence of basicity on the metallurgical performances and reduction characteristics of fired super high-grade magnetite pellets under the simulated shaft furnace gas conditions was investigated.The fired pellets in the basicity range of 0.09(natural basicity)to 1.00 show superior reducibility and low-temperature disintegration performance.However,in the basicity range of 0.20–0.80,the abnormal swelling of the fired pellets occurs.Improving basicity from 0.09 to 0.40 promotes the generation of low melting point slag phases and lower porosity of fired pellets,and accelerates the growth and densification of hematite crystals,impeding the reduction of hematite particles and the formation of metallic iron shell.In addition,the slags that distribute between the hematite particles absorb the reduction stresses by increased distances between the particles during the reduction process,which leads to the large reduction swelling of pellets.展开更多
基金financially supported by the National Natural Science Foundation of China(No.52004339)the Key Research and Development Project of Hunan Province,China(No.2022SK2075)+1 种基金China Baowu Low Carbon Metallurgy Innovation Foundation(BWLCF202216)Central South University Graduate Student Independent Exploration and Innovation Project(2024ZZTS0378).
文摘The self-reforming of coke oven gas(COG)in a gas-based shaft furnace was investigated,employing metallized iron as a catalyst.Thermodynamic analyses,supported by FactSage 8.3 calculations and regression modeling,were used to investigate the effects of temperature(700–1100℃),CO_(2)(3%–10%),and H_(2)O(1%–9%)concentrations on CH_(4) conversion efficiency.Results indicate that CH_(4) conversion exceeds 90%at temperatures above 1000℃,with CO_(2) and H_(2)O concentrations at 9%and 5%,respectively.During the reforming process,introducing CO_(2) provides additional oxygen,facilitating the oxidation of CH_(4),while H_(2)O enhances H_(2) production through the steam reforming pathway.Experimental findings reveal a CH_(4) conversion of 85.83%with a H_(2)/CO ratio of 5.44 at 1050℃.In addition,an optimal H_(2)O concentration of 6%yields the highest CH_(4) conversion of 84.24%,while CO_(2) exhibits minimal effects on promoting the reforming process.Increasing the metallization rate of pellets from 43%to 92%significantly enhances CH_(4) reforming.This is mainly due to the fact that metallized iron is vital in promoting CH_(4) dissociation and improving syngas yield by providing active sites for the redox cycle of CO_(2) and H_(2)O.
基金supported by the National Key R&D Program of China(Grant Nos.2021YFC2902400 and 2021YFC2902404)Interdisciplinary Research Project for Young Teachers of USTB(Fundamental Research Funds for the Central Universities)(FRF-IDRY-21-027 and FRF-IDRY-22-018).
文摘With the depletion of high-quality iron ore resources,high-phosphorus oolitic hematite(HPOH)has attracted great attention due to its large reserve and relatively high iron content.However,HPOH is very difficult to be used in ironmaking process due to its special structure.A two-step method of gas-based direct reduction and magnetic separation was thus proposed to recover iron and reduce phosphorus.The results showed that the powdery reduced iron produced contained 92.31%iron and 0.1%phosphorus,and the iron recovery was 92.65%under optimum reduction condition,which is suitable for following steelmaking.The apatite will be reduced under long reduction time and a large reducing gas flow rate,resulting in more phosphorus found in the metallic iron.Increasing the hydrogen–carbon ratio will inhibit the formation and growth of iron particles and prevent the breakage of oolitic structure.Careful adjustment of reduction temperature is recommended as it affects the oolitic structure and reduction.
基金Sponsored by National Natural Science Foundation of China and Baosteel(50834007)
文摘A new method （gas-based separation plus melt separation） has been proposed to remove phosphorus of the high phosphorus iron ore which was 1.25 % of phosphorus content and 50. 0% of iron content. HSC chemistry package and the coexistence theory of slag structure were adopted for theoretical analysis. The gas-based reduction was carried out using a fixed bed reactor and the ore sample of 80 g with an average particle size of 2 mm were reduced using CO or H2 at temperature of 1 073 K for 5 hours. 50 g of the reduced sample with 3.0% CaO as additive was then subjected to melt separation in an electric furnace at temperature of 1 873 K under Ar atmosphere. In each run, SEM, EDS, optical microscopic examination and chemical analysis of the reduced ore sample, the metal sample and the slag sample were conducted. Results of all gas-based reduction experiments showed that iron metallization ratios were some 65% and the phosphorus compounds in the ore remained unchanged. It was agreed well with the simula- tions except for the iron metallization rate being less than predicted value; this difference was attributed to kinetics. Results of melt separation experiments showed that P content in metal samples is 0.33% （metal sample from H2 reduction product） and 0.27% （metal sample from CO reduction product）. The phosphorus partition ratios of both cases were less than predicted values. Some P in the metal samples existed as slag inclusion was considered to be the reason for this discrepancy.
基金financially supported by the Ministry of Land and Resources Public Welfare Industry Research Project, China (No. 201511062-02)
文摘Numerous studies have focused on the reduction thermodynamics of ordinary iron ore;by contrast, the literature contains few thermodynamic studies on the gas-based reduction of vanadium titano-magnetite (VTM) in mixed atmospheres of H2, CO, H2O, CO2, and N2. In this paper, thermodynamic studies on the reduction of oxidized VTM pellets were systematically conducted in an atmosphere of a C–H–O system as a reducing agent. The results indicate that VTM of an equivalent valence state is more difficult to reduce than ordinary iron ore. A reduction equilibrium diagram using the C–H–O system as a reducing agent was obtained;it clearly describes the reduction process. Experiments were performed to investigate the effects of the reduction temperature, the gas composition, and two types of iron ores on the reduction of oxidized VTM pellets. The results show that the final reduction degree increases with increasing reduction temperature, increasing molar ratio of H2/(H2 + CO), and decreasing H2O, CO2, and N2 contents. In addition, the reduction processes under various conditions are discussed. All of the results of the reduction experiments are consistent with those of theoretical thermodynamic analysis. This study is expected to provide valuable thermodynamic theory on the industrial applications of VTM.
基金Project(50725416) supported by National Natural Science Funds for Distinguished Young Scholars of China
文摘Alastraet： The gas-based direct reduction of iron ore pellets was carried out by simulating the typical gas composition in coal gasification process, Midrex and HyMII processes. The influences of gas composition and temperature on reduction were studied. Results show that the increasing of HE proportion is helpful to improve the reduction rate. However, when ~o（H2）：~o（CO）〉1.6：1, changes of HE content have little influence on it. Appropriate reduction temperature is about 950 ℃, and higher temperature （1 000 ℃） may unfavorably slow the reduction rate. From the kinetics analysis at 950 ℃, the most part of reduction course is likely controlled by interfacial chemical reaction mechanism and in the final stage controlled by a combined effect of gaseous diffusion and interfacial chemical reaction mechanisms. From the utilizations study of different reducing gases at 950 ℃, the key step in reduction course is the 3rd stage （FeO→Fe）, and the utilization of reducing gas increases with the rise of HE proportion.
基金financially supported by the National Natural Science Foundation of China (No.51904063)the China Postdoctoral Science Foundation (No.2018M640259)+2 种基金the Fundamental Research Funds for the Central Universities(No.N2025023)the Key research and development project of Hebei Province (No.21314001D)the Plan of Xingliao Talents,China (No.XLYC1902118)。
文摘Hydrogen-based shaft furnace process is gaining more and more attention due to its low carbon emission, and the reduction behavior of iron bearing burdens significantly affects its operation. In this work, the effects of reduction degree, temperature, and atmosphere on the swelling behavior of pellet has been studied thoroughly under typical hydrogen metallurgy conditions. The results show that the pellets swelled rapidly in the early reduction stage, then reached a maximum reduction swelling index (RSI) at approximately 40%reduction degree. The crystalline transformation of the iron oxides during the reduction process was the main reason of pellets swelling. The RSI increased significantly with increasing temperature in the range of 850-1050℃, the maximum RSI increased from 6.66%to 25.0%in the gas composition of 100%H_(2). With the temperature increased, the pellets suffered more thermal stress resulting in an increase of the volume. The maximum RSI decreased from 19.78%to 17.35%with the volume proportion of H_(2) in the atmosphere increased from 55%to 100%at the temperature of 950℃.The metallic iron tended to precipitate in a lamellar structure rather than whiskers. Consequently, the inside of the pellets became regular, so the RSI decreased. Overall, controlling a reasonable temperature and increasing the H_(2) proportion is an effective way to decrease the RSI of pellets.
基金financially supported by National Natural Science Foundation of China(Grant No.51574067)
文摘Hongge vanadium titanomagnetite（HVTM）pellets were reduced by H2-CO gas mixture for simulating the reduction processes of Midrex and HYL-III shaft furnaces.The influences of reduction temperature,ratio ofφ（H2）toφ（CO）,and pellet size on the reduction of HVTM pellets were evaluated in detail and the reduction reaction kinetics was investigated.The results show that both the reduction degree and reduction rate can be improved with increasing the reduction temperature and the H2 content as well as decreasing the pellet size.The rational reduction parameters are reduction temperature of 1050℃,ratio ofφ（H2）toφ（CO）of 2.5,and pellet diameter in the range of 8-11 mm.Under these conditions（pellet diameter of 11mm）,final reduction degree of 95.51% is achieved.The X-ray diffraction（XRD）pattern shows that the main phases of final reduced pellets under these conditions（pellet diameter of 11 mm）are reduced iron and rutile.The peak intensity of reduced iron increases obviously with the increase in the reduction temperature.Besides,relatively high reduction temperature promotes the migration and coarsening of metallic iron particles and improves the distribution of vanadium and chromium in the reduced iron,which is conducive to subsequent melting separation.At the early stage,the reduction process is controlled by interfacial chemical reaction and the apparent activation energy is 60.78kJ/mol.The reduction process is controlled by both interfacial chemical reaction and internal diffusion at the final stage,and the apparent activation energy is 30.54kJ/mol.
基金The authors want to express their gratitude for the financial support from the National Natural Science Foundation of China(No.52004075)Science and Technology Planning Projects of Guizhou Province(No.ZK[2021]262)+1 种基金Program Foundation for Talents of Guizhou University(No.(2020)15)the Hunan Provincial Co-innovation Center for Clean and Efficient Utilization of Strategic Metal Mineral Resources.
文摘The influence of basicity on the metallurgical performances and reduction characteristics of fired super high-grade magnetite pellets under the simulated shaft furnace gas conditions was investigated.The fired pellets in the basicity range of 0.09(natural basicity)to 1.00 show superior reducibility and low-temperature disintegration performance.However,in the basicity range of 0.20–0.80,the abnormal swelling of the fired pellets occurs.Improving basicity from 0.09 to 0.40 promotes the generation of low melting point slag phases and lower porosity of fired pellets,and accelerates the growth and densification of hematite crystals,impeding the reduction of hematite particles and the formation of metallic iron shell.In addition,the slags that distribute between the hematite particles absorb the reduction stresses by increased distances between the particles during the reduction process,which leads to the large reduction swelling of pellets.
