The behavior of metallized pellets containing zinc dust and mud(hereinafter referred to as metallized pellets)in the smelting process of a blast furnace is crucial for its widespread application as a new type of blast furnace raw material.The gas-solid reduction process of metallized pellets in a blast furnace were simulated in laboratory combined with microscopic detection methods to research the reduction characteristics and kinetics of metallized pellets.The results indicate that the uniform dispersion of iron oxides within the metallized pellets and its loose porous structure are favorable for the gas-solid reduction reaction.The reduction reaction is mainly indirect reduction,and the reduction rate increases rapidly at the beginning of the reduction process,the reduction rate is 93.51％at 1 000 ℃.The harmful element Zn in the metallized pellets is rapidly reduced and gasified at 850-900 ℃,this temperature is slightly below its boiling point.However,harmful element S does not exhibit reduction behavior at temperatures below 1 000 ℃.There is a certain correlation between changes in residual carbon content and changes in zinc content;in less than 3 000 seconds,the interfacial chemical reaction becomes a limiting link in the gas-solid reduction of metallized pellets,which then transforms into gas diffusion.This is related to the gradual increase and agglomeration of metal iron in the metallized pellets,and the continuous increase in pellet density caused by the filling of pores with slag phase.The apparent activation energies for the two limiting steps are 23.76 kJ/mol and 74.20 kJ/mol,respectively,the gas-solid reduction reaction in the metallized pellets is more favorable and easily proceeds.
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