Deterioration of Blast Furnace Coke by CO₂ Gasification

Abstract

The deterioration of coke in the blast furnace was taken as the change in coke size with the reaction between the coke and CO₂ gas. To clarify this reaction mechanism, a series of experiments were carried out, using apparatus for measuring coke strength after CO₂ reaction. The findings obtained are as follows:
(1) The process of progress of the reaction between the coke and CO₂ gas can be analyzed by a single-particle model.
(2) As a result, a homogeneous-phase model or an unreacted-core model may be considered to represent the reaction type of lump coke.
(3) When coke contains a large amount of isotropic textures, the reaction proceeds at the surface. The type of this reaction is close to that represented by the unreacted-core model.
(4) When coke has a high porosity, the CO₂ gas permeates the inside of coke lump along the pores. The type of this reaction is close to that represented by the homogeneous-model.
(5) The difference between these two types of reaction depends on the matrix nature and structure of coke.
(6) Based on the above findings, the conditions required of coke that is not readily reduced in size by CO₂ gasification are proposed.