A significant amount of CO_(2) gas is emitted from blast furnaces in ironmaking processes because large amounts of coke and pulverized coal are consumed as the reducing agent and heat source. Accordingly, CO_(2) emissions from blast furnaces should be reduced to control global warming. One promising method to achieve the CO_(2) reduction involves decreasing the reducing agent rate (RAR) during blast furnace operation. However, fine particles such as ash, derived from coke and pulverized coal, may affect the permeability in the furnace under low RAR operation. Therefore, the behavior of ash particles in a coke lump during combustion and gasification was elucidated experimentally in this work. Combustion and gasification experiments on a single coke lump were conducted in air and in a CO–CO_(2) gas mixture atmosphere at temperatures from 1473 to 1673 K. The ash particles in the coke lump were observed using a scanning electron microscope (SEM). Many large ash particles were observed near the surface of the coke lump during combustion. This is because the ash particles coalesced with the neighboring ash particles near the surface. Only molten fine ash particles were formed during gasification. This difference in the ash behavior during combustion from gasification will depend on the consumption behavior of the carbonaceous matrix.
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