| 摘要 |
PURPOSE:To improve air-permeability in the softening and melting zone of a blast furnace, to make the flow of in-furnace gas smooth and to stabilize blast furnace operation, by executing one or more of the distribution control of material charged at the top of the furnace, the charge of prereduced ore and the injection of reducing gas. CONSTITUTION:The softening contraction ratio of minerals or the like to be charged to a blast furnace is detected by a temperature-raised load-softening test proximate to a reducing condition in the blast furnace. In addition, the reliability of a softening viscosity on a temperature and a prereducing ratio is detected on the basis of the measured contraction value of prereduced charged materials under an isothermal fixed load condition. A reducing ratio in a 1,000 deg.C (the initiation temperature of softening contraction)-zone in the furnace, preferably in the 1,000 deg.C-zone at the periphery in the range from the furnace wall to a position being 15% of the radius of the furnace, obtained from a reaction mechanism model in the blast furnace is controlled at a level higher by 10% or more than that at which a softening viscosity is the minimum. In this regard, the air-permeability of the blast furnace is improved by executing one or more of the distribution control of materials charged at the top of the furnace, the charge of prereduced minerals and the injection of reducing gas through a shaft part. |
