| 摘要 |
PURPOSE:To improve the economical efficiency of blast furnace operation by studying the migration mechanism of Si into pig iron, detecting melt dropping distance Hc from operation data with high accuracy and so operating the blast furnace that Hc becomes as small as possible based on the results of detection, in blast furnace operation. CONSTITUTION:When in the blast furnace operation the value of so-called melt dropping distance Hc between the level 9 of the root part 5 bottom end of the fusion bond layer 4 of the iron ore layer 2 in the furnace and the level 10 of the tuyere 11 raceway 8 becomes smaller, the furnace temperature lowers and when it becomes larger, the fuel ratio increases and the Si content in the molten iron increases. Hence, the melt dropping distance Hc of iron ore is obtained by formula (1) from the activity Asio2 of SiO2 calculated based on the polynomial of the molar fraction of SiO2 in the slag obtainable from the analytical value of the slag composition, the CO partial pressure Pco of combustion zone, tapping ratio gamma, molten iron temperature Tp and the Si concentration [%SiO2] in molten iron. One or a plurality of factors of the slag composition, blast factor, tapping ratio, fuel ratio, molten iron temperature and flame temperature are controlled so that the value of Hc becomes target value, whereby the furnace conditions are maintained in the best state. |
