Abstract
A porous Al2O3-Fe2O3 tube, the inside of which is evacuated, is used to decarburize molten iron. Effects of inside pressure and Fe2O3 content of the porous tube, initial carbon content of the melt and melt temperature on the decarburization rate are investigated. Evacuating the inside of the tube reduces the partial pressure of CO at the tube-melt interface and enhances the decarburization reaction. However, in the case of lower initial carbon content of the melt, liquid slag is formed at the surface of higher Fe2O3 content tube, and sucked into its pore. Penetration of the liquid slag into the tube reduces the thermal strength and leads to the tube deformation. As a result, the gas permeability of the tube is decreased, and the decarburization rate becomes lower. The apparent decarburization rate constant (apparent first-order rate constant) for the non-deformed tube increases with increasing Fe2O3 content and decreasing inside pressure of the tube. At higher carbon contents, the tube is not severely deformed, but the effect of evacuation on the decarburization rate is little due to formation of large amount of CO (or CO boiling). The apparent decarburization rate constant decreases with increasing initial carbon content, and hence the rate is presumed to be controlled mainly by oxygen supply from the tube. The apparent activation energy for the decarburization reaction is 72.5 kcal/mol.
