PURPOSE: To reduce the amounts of powder and fluid blown without weakening the effect of low silicon operation by measuring the luminance of a raceway or the temp. of coke and starting or stopping the blowing of powder and fluid when the measured value exceeds a control limit.

CONSTITUTION: The luminance of a raceway before a tuyere of a blast furnace or the temp. of coke is measure. The temp. of gas may be measured. When the measured value exceeds the standard value of the upper control limit, the blowing of powder and fluid from the tuyere is started. When the measured value falls below the standard value of the lower control limit, the blowing of powder of fluid is stopped. The amounts of powder and fluid blown may be proportionally controlled according to the measure value. By this low Si operation of the blast furnace, the cost of starting materials is reduced.