Benefits and Risks of High-Intensity Blast-Furnace Operation

Abstract

More intense blast-furnace operation at OAO NLMK has been made possible by improvement in quality of the coke and the iron-ore products, increase in pressure below the charge hole, and oxygen enrichment of the blast. That increases the rate of indirect wustite reduction and decreases the heat losses to the cooling water. However, high intensity also significantly increases the risks of accidents in batch admission. Besides change in quality of the batch components, the disruptions in batch descent may be due to change in the ore distribution over the furnace radius. A new diagnostic method has been developed to identify the factors responsible for such disruptions. Simulation permits analysis of the influence of change in the ore load and the size of the iron-ore products on the temperature change of the peripheral gases and the utilization of the carbon monoxide. The method is based on analysis of the total change in gas temperature and the utilization of the carbon monoxide in the peripheral region. On that basis, the factors responsible for the change in the pressure difference over the furnace height may be identified. Analysis of the dynamics of the pressure differences over the furnace height permits judgments regarding the probability of disruptions in batch delivery. The possibility of decreasing the pressure difference by redistribution of the ore over the furnace radius and decreasing the quantity of gas is assessed. Various methods of decreasing the quantity of gas are accompanied by changes in the coke consumption and furnace productivity. A mathematical model has been developed for the selection of the best combination of blast adjustments for specific conditions.