The mineral composition of the sinter affects the quality of cold-bonded briquettes(CBB),which are prepared from returned sinter fines and serve as a cleaner blast furnace charge.Pulverization rate,compressive strengt...The mineral composition of the sinter affects the quality of cold-bonded briquettes(CBB),which are prepared from returned sinter fines and serve as a cleaner blast furnace charge.Pulverization rate,compressive strength,reduction disintegration index(RDI)and compressive strength after reduction experiment were tested to analyze the experimental parameters of CBB under the influence of different basicities and sintering time.The results show that when the basicity of CBB is increased from 0.5 to 1.5,the pulverization rate increases,and performance indexes such as compressive strength,RDI,and compressive strength exhibit a decreasing trend.When the basicity is increased from 1.5 to 3.0,all the aforementioned performance indexes are improved.When the sintering time is extended from 0 to 8 h,the properties mentioned above are improved.The results of X-ray diffraction,microstructure,and thermodynamic calculations confirm that the hematite in the mineral composition of CBB tends to convert into calcium ferrite,which leads to the increased compressive strength of CBB.The reasonable basicity and sintering time during sinter preparation not only form the desired mineral composition but also improve the properties of the CBB.展开更多
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
基金supported by Distinguished Professor(Tracking Plan)of Oriental Scholars of Shanghai Universities(Grant No.GZ2020013)National 111 Project(The Program of Introducing Talents of Discipline to University)(Grant No.Dl7002)+1 种基金Independent Research Project of State Key Laboratory of Advanced Special Steel Shanghai Key Laboratory of Advanced Ferrometallurgy and Shanghai University(Grant No.SKLASS 2022-Z011)Additionally,the authors are appreciative of the funding from the Academy of Finland with Grant No.349833.
文摘The mineral composition of the sinter affects the quality of cold-bonded briquettes(CBB),which are prepared from returned sinter fines and serve as a cleaner blast furnace charge.Pulverization rate,compressive strength,reduction disintegration index(RDI)and compressive strength after reduction experiment were tested to analyze the experimental parameters of CBB under the influence of different basicities and sintering time.The results show that when the basicity of CBB is increased from 0.5 to 1.5,the pulverization rate increases,and performance indexes such as compressive strength,RDI,and compressive strength exhibit a decreasing trend.When the basicity is increased from 1.5 to 3.0,all the aforementioned performance indexes are improved.When the sintering time is extended from 0 to 8 h,the properties mentioned above are improved.The results of X-ray diffraction,microstructure,and thermodynamic calculations confirm that the hematite in the mineral composition of CBB tends to convert into calcium ferrite,which leads to the increased compressive strength of CBB.The reasonable basicity and sintering time during sinter preparation not only form the desired mineral composition but also improve the properties of the CBB.
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.
