on the basis of the results of dissection of Nagoya No. 1 blast furnace, studies have been made on the degradation of coke in a large blast furnace. The results o f these studies show as follows.
(1) The degradation of coke in a blast furnace is greatly influenced by the temperature wherein coke is subjected to the CO₂ reaction.
(2) Lump coke, which begins to degrade due to the selective solution loss and the decrease in strength at 1 000°C, does not change the grain size up to 1 400°C but begins to reduce the size markedly above 1 400°C.
(3) Coke fines deposited between the lower part of shaft and the tuyeres are concentrated in the vicinity of raceway and moved by the kinetic energy of gas.
(4) The increase in the alkali content of coke (by 5% maximum in the present study) does not decrease the strength of coke. Further, the relationships between the inner volumes of dissected blast furnaces and the change in the properties of coke charged in furnaces were studies. The results of this study suggest that the size reduction ratio of coke particle is higher and the degradation conditions of coke become more strict in the case of large blast furnace than that of small one.