REDUCTION BEHAVIOR OF MAGNETITE PELLETS BY CO-CO_2 MIXTURES USING DIRECT REDUCTION PROCESS

摘要

In this study reduction kinetics and swelling behaviors in "two-step process" were investigated by weight-loss technique and visualizing physical changes of pellet. Results showed that reduction degree (r) increased with increasing temperature and time. According to the dynamic calculation, when reduction temperature was lower than 1000°C the reduction process was controlled by chemical reaction with apparent activation energy of 72.27 kJ/mol. When reduction temperature was higher than 1000°C, the equation of t/[l-(l-r)~(1/3)] against [l+2(l-r)-3(l-r)~(2/3)]/[l-(l-r)~(1/3)] followed straight lines, demonstrating that reduction was mixed-controlled. Swelling experiments indicated that the maximum swelling index increased with the increase of reduction temperature and CO content.