Blast Furnace Operation for Low Silicon Content at Fukuyama No. 5 Blast Furnace

The low silicon operation with the silicon content of less than 0.2 % was performed for 16 months from January, 1988 to April, 1989 at Fukuyama No. 5 blast furnace of NKK Corp. The following are the factors attributable to this longterm low Si performance. 1) Prevention of temperature drop of hot metal in the hearth by the decrease in heat loss from the hearth associated with the improvement of tapping conditions 2) Decrease in heat loss from the shaft and prevention of inactivated state in the lower part of the furnace by the improvement of burden distribution 3) Stable operation based on an expert system for furnace heat control and burden distribution control Low Si content operation was accomplished by lower flame temperature which resulted in the restraint of SiO gas formation and higher thermal flow ratio which contributed to lowering the cohesive zone level.