The hydrogen reduction of Panzhihua ilmenite concentrate in the temperature range of 900?1050 °C was systematicallyinvestigated by thermogravimetric analysis (TG), X-ray diffraction (XRD) and scanning electron mi...The hydrogen reduction of Panzhihua ilmenite concentrate in the temperature range of 900?1050 °C was systematicallyinvestigated by thermogravimetric analysis (TG), X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods. It wasshown that the products of the Panzhihua ilmenite reduced at 900 °C were metallic iron and rutile. Above 1000 °C, ferrouspseudobrookite solid solution was generated. During the reduction process, element Mg gradually concentrated to form Mg-rich zonewhich can influence the metallization process. The reduction reaction proceeded topochemically and its related reduction kineticswere also discussed. The kinetics of the reduction indicated that the rate-controlling step was the diffusion process. The apparentactivation energy of the hydrogen reduction of Panzhihua ilmenite was calculated to be 117.56 kJ/mol, which was larger than that ofsynthetic ilmenite under the same reduction condition.展开更多
The gasification characteristics and gasification kinetics of coke in complex CO2/CO/H2/H2O/N2 systems similar to the gas system of industrial blast furnace (BF) were studied by the method of isothermal thermogravimet...The gasification characteristics and gasification kinetics of coke in complex CO2/CO/H2/H2O/N2 systems similar to the gas system of industrial blast furnace (BF) were studied by the method of isothermal thermogravimetric analysis. The experimental gas compositions and the corresponding temperature were chosen according to data reported for industrial BFs. The gasification behavior of coke was described by the Random Pore Model (RPM), Volumetric Model (VM), and Grain Model (GM). Results showed that the gas composition of the coke gasification zone in BF changes slightly and that the temperature is the most important factor affecting coke gasification. The lower activation energy of coke samples (Coke Reaction Index (CRI)>50) is due to the high Fe2O3 in the ash, lower degree of graphitization, and larger pore structure. In addition, the choice of kinetic model does not differ substantially in describing the gasification mechanism of coke in a BF.展开更多
Iron ore powder was isothermally reduced at 1023-1373 Kwith hydrogen/carbon monoxide gas mixture(from 0vol%H2/100vol%CO to 100vol%H2/0vol%CO).Results indicated that the whole reduction process could be divided i...Iron ore powder was isothermally reduced at 1023-1373 Kwith hydrogen/carbon monoxide gas mixture(from 0vol%H2/100vol%CO to 100vol%H2/0vol%CO).Results indicated that the whole reduction process could be divided into two parts that proceed in series.The first part represents a double-step reduction(Fe2O3→Fe3O4→FeO),in which the kinetic condition is more feasible compared with that in the second part representing a single-step reduction(FeO→Fe).The influence of hydrogen partial pressure on the reduction rate gradually increases as the reaction proceeds.The average reduction rate of hematite ore with pure hydrogen is about three and four times higher than that with pure carbon monoxide at 1173 and 1373 K,respectively.In addition,the logarithm of the average rate is linear to the composition of the gas mixture.Hydrogen can prominently promote carbon deposition to about 30%at 1023 K.The apparent activation energy of the reduction stage increases from about 35.0 to 45.4 kJ/mol with the increase in hydrogen content from 20vol%to 100vol%.This finding reveals that the possible rate-controlling step at this stage is the combined gas diffusion and interfacial chemical reaction.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 package and the...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 1073 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 1873 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
Isothermal thermogravimetric analysis was used to study the reduction process of solid/liquid wustite by hydrogen.Results show that wustite in both states can be reduced entirely at all temperatures.The thermal and ki...Isothermal thermogravimetric analysis was used to study the reduction process of solid/liquid wustite by hydrogen.Results show that wustite in both states can be reduced entirely at all temperatures.The thermal and kinetic conditions for the hydrogen reduction of molten phases are better than those when the reactants and products are in the solid state,with a higher reaction rate.The hydrogen reduction of different wustite phases fits the Mampel Power model(power exponent n=1/2)well,and this model is independent of the phase state.The average apparent activation energies of the reduction process calculated by the iso-conversional method are 5.85 kJ·mol−1 and 104.74 kJ·mol−1,when both reactants and products are in the solid state and the molten state,respectively.These values generally agree with those calculated by the model fitting method.展开更多
基金Project(2014CB643403)supported by the National Basic Research Program of ChinaProjects(51225401,51304132,51574164)supported by the National Natural Science Foundation of China+1 种基金Project(14JC1491400)supported by the Science and Technology Commissions of Shanghai Municipality,ChinaProject(2013GZ0146)supported by the Sichuan Province,China
摘要The hydrogen reduction of Panzhihua ilmenite concentrate in the temperature range of 900?1050 °C was systematicallyinvestigated by thermogravimetric analysis (TG), X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods. It wasshown that the products of the Panzhihua ilmenite reduced at 900 °C were metallic iron and rutile. Above 1000 °C, ferrouspseudobrookite solid solution was generated. During the reduction process, element Mg gradually concentrated to form Mg-rich zonewhich can influence the metallization process. The reduction reaction proceeded topochemically and its related reduction kineticswere also discussed. The kinetics of the reduction indicated that the rate-controlling step was the diffusion process. The apparentactivation energy of the hydrogen reduction of Panzhihua ilmenite was calculated to be 117.56 kJ/mol, which was larger than that ofsynthetic ilmenite under the same reduction condition.
基金financially supported by the National Key Research and Development Program of China (Nos. 2017YFB0304300 and 2017YFB0304303)the National Science Foundation of China (No. 51774032)the Chinese Fundamental Research Funds for the Central Universities (No. FRF-TP-17-086A1)
摘要The gasification characteristics and gasification kinetics of coke in complex CO2/CO/H2/H2O/N2 systems similar to the gas system of industrial blast furnace (BF) were studied by the method of isothermal thermogravimetric analysis. The experimental gas compositions and the corresponding temperature were chosen according to data reported for industrial BFs. The gasification behavior of coke was described by the Random Pore Model (RPM), Volumetric Model (VM), and Grain Model (GM). Results showed that the gas composition of the coke gasification zone in BF changes slightly and that the temperature is the most important factor affecting coke gasification. The lower activation energy of coke samples (Coke Reaction Index (CRI)>50) is due to the high Fe2O3 in the ash, lower degree of graphitization, and larger pore structure. In addition, the choice of kinetic model does not differ substantially in describing the gasification mechanism of coke in a BF.
基金financial support provided by Tata Steel Limited and State Key Laboratory of A dvanced Metallurgy(USTB)。
摘要Iron ore powder was isothermally reduced at 1023-1373 Kwith hydrogen/carbon monoxide gas mixture(from 0vol%H2/100vol%CO to 100vol%H2/0vol%CO).Results indicated that the whole reduction process could be divided into two parts that proceed in series.The first part represents a double-step reduction(Fe2O3→Fe3O4→FeO),in which the kinetic condition is more feasible compared with that in the second part representing a single-step reduction(FeO→Fe).The influence of hydrogen partial pressure on the reduction rate gradually increases as the reaction proceeds.The average reduction rate of hematite ore with pure hydrogen is about three and four times higher than that with pure carbon monoxide at 1173 and 1373 K,respectively.In addition,the logarithm of the average rate is linear to the composition of the gas mixture.Hydrogen can prominently promote carbon deposition to about 30%at 1023 K.The apparent activation energy of the reduction stage increases from about 35.0 to 45.4 kJ/mol with the increase in hydrogen content from 20vol%to 100vol%.This finding reveals that the possible rate-controlling step at this stage is the combined gas diffusion and interfacial chemical reaction.
基金Sponsored by National Natural Science Foundation of China and Baosteel(50834007)
摘要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 1073 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 1873 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 National Natural Science Foundation of China(Nos.51874025 and 52174291)。
摘要Isothermal thermogravimetric analysis was used to study the reduction process of solid/liquid wustite by hydrogen.Results show that wustite in both states can be reduced entirely at all temperatures.The thermal and kinetic conditions for the hydrogen reduction of molten phases are better than those when the reactants and products are in the solid state,with a higher reaction rate.The hydrogen reduction of different wustite phases fits the Mampel Power model(power exponent n=1/2)well,and this model is independent of the phase state.The average apparent activation energies of the reduction process calculated by the iso-conversional method are 5.85 kJ·mol−1 and 104.74 kJ·mol−1,when both reactants and products are in the solid state and the molten state,respectively.These values generally agree with those calculated by the model fitting method.