The temperature control technology of the thermal reserve zone is examined as a technology which drastically improves reaction efficiency in the blast furnace, and the usage technology of high reactivity coke is proposed.
The adaibatic blast furnace simulator which is able to simulate the temperature transition and the gas volume change according to the coke reaction under ore and coke coexistence is developed.
Following findings are obtained.
The starting temperature of coke reaction corresponds to the temperature of the thermal reserve zone (Ttrz).
Ttrz has decreased along with the rise of the coke reactivity. The blast furnace reaction efficiency improves by using high reactivity coke voluminously and by mixing using the small-size high reactivity coke and sinter.
The decrease of the fuel ratio of about 25-35 kg/t can be expected by using the high reactivity coke.
The factors of reaction efficiency improvement by using the high reactivity coke are shown as follows.
(1) Transition of FeO-Fe reduction equilibrium point (W point), that is, decrease of thermal reserve zone temperature, (2) Improvement of the gas reduction ability by the coke reaction, (3) Increase of micro-pore volume according to reduction from wustite to iron, (4) Decrease of melt generation and control of pore decrease by reduction of CW (calcio-wustite), (5) Gas reduction promotion by increase of porosity.
