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
The microwave heating characteristics of the mixture with oxidized pellet and coal was studied, and the non-isothermal reduction dynamics is discussed. The results show that, the slow-heating stage of the temperature ...The microwave heating characteristics of the mixture with oxidized pellet and coal was studied, and the non-isothermal reduction dynamics is discussed. The results show that, the slow-heating stage of the temperature rising process can be segmented into two heating temperature curves approximately that have good linear relation- ship. They can be seen as temperature programming. In the first stage, between 827 and 1073 K, the reaction mechanism obeys diffusion controlled model. In the second stage, between 1 093 and 1 323 K, the reaction mecha- nism also obeys diffusion controlled model. The apparent activation energies are found to be 75.13 kJ/mol for the first stage and 53.17 kJ/mol for the second stage. That is lower than the apparent activation energy under conven- tional heating. The microstructure of the reduced pellets shows that microwave can improve the kinetics of the reduc- tion. Microwave has anxo-action to the reaction obviously.展开更多
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Sponsored by National Science Fund for Distinguished Young Scholars of China(50725416)
文摘The microwave heating characteristics of the mixture with oxidized pellet and coal was studied, and the non-isothermal reduction dynamics is discussed. The results show that, the slow-heating stage of the temperature rising process can be segmented into two heating temperature curves approximately that have good linear relation- ship. They can be seen as temperature programming. In the first stage, between 827 and 1073 K, the reaction mechanism obeys diffusion controlled model. In the second stage, between 1 093 and 1 323 K, the reaction mecha- nism also obeys diffusion controlled model. The apparent activation energies are found to be 75.13 kJ/mol for the first stage and 53.17 kJ/mol for the second stage. That is lower than the apparent activation energy under conven- tional heating. The microstructure of the reduced pellets shows that microwave can improve the kinetics of the reduc- tion. Microwave has anxo-action to the reaction obviously.
