高炉操業におよぼす焼結鉱還元粉化性状の影響

抄録

Fundamental experiments on the degradation of sinter during reduction were carried out and the correlation between the reducing conditions and the degree of size degradation was evaluated quantitatively. On the basis of these results, the size degradation of sinter in the blast furnace was estimated and the influences of size degradation on the blast furnace operation were investigated.
(1) The effects of reducing conditions can be summarized as follows.
a) At any temperature, the rate of decrease in size is reduced with the increase in reduction degree. When the reducing temperature is below 525°C, the size degradation is related only to the reduction degree and is independent of the reducing temperature.
b) The size degradation becomes remarkable with the increase in initial size before reduction.
c) The CO concentration and the flow rate of reducing gas do not substantially influence the degradation behavior, but exclusively influence the reduction rate.
(2) The decrease in sinter size due to the degradation during reduction lowers the gas permeability in the blast furnace.
(3) When the sinter size in the furnace decreases, the gas utilization becomes worse due to the change in gas flow and the fuel rate increases. On the contrary, when the sinter size becomes excessively large, the fuel rate decreases due to the decrease in reducibility and low gas utilization by the decrease in reduction surface. Therefore, it is expected that the optimum sinter size in the furnace exists.