Effects of Carbon Containing of the Inner Layer on Reduction Swelling of Double-layer Structure of Pellet

Magnetite powder and hematite powder are employed as raw material to form double-layer structure of pellet respectively,the influence of addition of carbon containing of the inner layer on magnetite and hematite double-layer structure of pellet reduction-swelling index(RSI) shows that the influence of addition of carbon(coke powder) of the inner layer on reduction swelling of magnetite and hematite double-layer structure of pellet makes significant difference in the same pellet forming process and roasting system.With the increase of the content of carbon,the magnetite pellet RSI decreases at first and then increases,having a lowest RSI of 7.98% at 1.0%(w).With the increase of the content of carbon,the hematite pellet RSI tends to decrease basically,having a lowest RSI of 9.52% at 1.5%.The specimens of pellet are characterized by reflex microscope,when the content of carbon is more than 1.0%,the magnetite pellet appeared in magnetite crystallization;when the content of carbon is more than 1.5%,the hematite pellet appeared in magnetite crystallization,pellet strength increases and RSIdecreases.