Cold-bonded pellets, to which a new type of inorganic binder was applied, were reduced by H2~CO mixtures with different HJCO molar ratios （1：0, 5：2, 1：1, 2：5, and 0：1） under various temperatures （1023, 1123, 1...Cold-bonded pellets, to which a new type of inorganic binder was applied, were reduced by H2~CO mixtures with different HJCO molar ratios （1：0, 5：2, 1：1, 2：5, and 0：1） under various temperatures （1023, 1123, 1223, 1323, and 1423 K） in a daermogravimetric analysis appaxatus. The effects of gas composition, temperature, and binder ratio on the reduction process were studied, and the microstxucture of re- duced pellets was observed by scanning electron microscopy-energy-dispersive spectrometry （SEM-EDS）. The SEM-EDS images show that binder particles exist in pellets in two forms, and the form that binder particles completely surround ore particles has a more significant hin- der effect on the reduction. The reduction equilibrium constant, effective diffusion coefficient, and the reaction rate constant were calculated on the basis of the unreacted core model, and the promotion effect of temperature on reduction was further analyzed. The results show that no sintering phenomenon occurred at low temperatures and that the increasing reaction rate constant and high gas diffusion coefficient could main- tain the promotion effect of temperature; however, when the sintering phenomenon occurs at high temperatures, gas diffusion is hindered and the promotion effect is diminished. The contribution of the overaJl equilibrium constant to the promotion effect depends on the gas composition.展开更多
The reduction of Fe3O4 to Fe is accomplished in two stages. In order to understand the reduction mechanism of magnetite cold bond pellets during the first period of heatingup process, it is necessary to study the kin...The reduction of Fe3O4 to Fe is accomplished in two stages. In order to understand the reduction mechanism of magnetite cold bond pellets during the first period of heatingup process, it is necessary to study the kinetics of the reaction. In this work, the first stage of reduction of magnetite cold bond pellets, that is the reduction from Fe3O4 to FeO, has been investigated using an isothermal thermogravimetric method. Isothermal experiments were carried out at 750℃, 800℃, 850℃ and 900℃, respectively. The results showed that the reaction was controlled by chemical reaction below 800℃, whereas, at higher temperature, it was controlled by a mixed controlled mechanism of chemical reaction and GinstlingBrounshtein diffusion as well.展开更多
针对湖南某含铅锌铁锰矿,开发了冷固球团-还原挥发-电炉熔分新工艺,先将矿粉与还原剂及粘结剂混合,造球后经低温固结,再送入回转窑还原。矿中铁还原为海绵铁;MnO2还原为MnO;同时铅、锌还原成金属态并挥发,在烟气中氧化并富集到烟尘中;...针对湖南某含铅锌铁锰矿,开发了冷固球团-还原挥发-电炉熔分新工艺,先将矿粉与还原剂及粘结剂混合,造球后经低温固结,再送入回转窑还原。矿中铁还原为海绵铁;MnO2还原为MnO;同时铅、锌还原成金属态并挥发,在烟气中氧化并富集到烟尘中;还原后的金属化球团直接进入电炉,通过熔分得到生铁和锰渣。实现了含铅锌铁锰矿的综合回收利用。回转窑还原挥发后的金属化球团中铅、锌含量较低,不会影响电炉炉衬寿命和操作,回收铅锌的同时省去了铁锰粉矿进电炉前需造块的工序。试验结果表明,在焦粉加入量为20%,硅石用量2.5%,1 390℃下熔分90 m in,得到生铁和锰渣,生铁中铁品位为95.72%,锰渣中锰品位为31.53%。展开更多
基金financially supported by the National Key Research and Development Program of China(2017YFB0304300 and 2017YFB0304302)the 111 Project(No.B13004)
文摘Cold-bonded pellets, to which a new type of inorganic binder was applied, were reduced by H2~CO mixtures with different HJCO molar ratios （1：0, 5：2, 1：1, 2：5, and 0：1） under various temperatures （1023, 1123, 1223, 1323, and 1423 K） in a daermogravimetric analysis appaxatus. The effects of gas composition, temperature, and binder ratio on the reduction process were studied, and the microstxucture of re- duced pellets was observed by scanning electron microscopy-energy-dispersive spectrometry （SEM-EDS）. The SEM-EDS images show that binder particles exist in pellets in two forms, and the form that binder particles completely surround ore particles has a more significant hin- der effect on the reduction. The reduction equilibrium constant, effective diffusion coefficient, and the reaction rate constant were calculated on the basis of the unreacted core model, and the promotion effect of temperature on reduction was further analyzed. The results show that no sintering phenomenon occurred at low temperatures and that the increasing reaction rate constant and high gas diffusion coefficient could main- tain the promotion effect of temperature; however, when the sintering phenomenon occurs at high temperatures, gas diffusion is hindered and the promotion effect is diminished. The contribution of the overaJl equilibrium constant to the promotion effect depends on the gas composition.
文摘The reduction of Fe3O4 to Fe is accomplished in two stages. In order to understand the reduction mechanism of magnetite cold bond pellets during the first period of heatingup process, it is necessary to study the kinetics of the reaction. In this work, the first stage of reduction of magnetite cold bond pellets, that is the reduction from Fe3O4 to FeO, has been investigated using an isothermal thermogravimetric method. Isothermal experiments were carried out at 750℃, 800℃, 850℃ and 900℃, respectively. The results showed that the reaction was controlled by chemical reaction below 800℃, whereas, at higher temperature, it was controlled by a mixed controlled mechanism of chemical reaction and GinstlingBrounshtein diffusion as well.
文摘针对湖南某含铅锌铁锰矿,开发了冷固球团-还原挥发-电炉熔分新工艺,先将矿粉与还原剂及粘结剂混合,造球后经低温固结,再送入回转窑还原。矿中铁还原为海绵铁;MnO2还原为MnO;同时铅、锌还原成金属态并挥发,在烟气中氧化并富集到烟尘中;还原后的金属化球团直接进入电炉,通过熔分得到生铁和锰渣。实现了含铅锌铁锰矿的综合回收利用。回转窑还原挥发后的金属化球团中铅、锌含量较低,不会影响电炉炉衬寿命和操作,回收铅锌的同时省去了铁锰粉矿进电炉前需造块的工序。试验结果表明,在焦粉加入量为20%,硅石用量2.5%,1 390℃下熔分90 m in,得到生铁和锰渣,生铁中铁品位为95.72%,锰渣中锰品位为31.53%。
