Abstract
By the data of basic open-hearth meltings, the relation of sulphur content between bath and slag, desulphurization velocity of ope-hearth steel and meaning of lime addition and slag off for desulphurization was studies. The sulphur content of basic slag (S) does not increase linearly as the sulphur content of bath [S] increase and approach gradually to a constant value.
Then the relation between (S)/[S] and basisity also varies with [S] content. The variation of [S] content during the smelting is representented in the next formula; d [S]/dt=-K/M[S]. This suggest that the desulphurization would be performed by the surface reaction between slag and bath and the velocity is controlled by the moving velocity of reactant in slag and bath. For desulphurization lime addition is very important, but slag off is effective to reduce the slag volume and to give the same desulphurizability.
