Abstract: Calcium aluminate flux is applied to RH desulphurization process protecting the refractories due to Fluoride free and easy storage condition request. In order to pursuit better effect of desulphurization,a new desulphurization model was constructed in this paper. The model was established and proved as the correlation coefficient equals 0.99. The values of the parameters could be got from the practice data of RH desulphurization. It could be concluded from the model that the process is decided by the effective time of desulphurization, which means terminal time of desulphurization minus the time reaching the critical liquid slag volume. The worst situation is when the melting speed of flux is too low to reaching the critical liquid slag volume, no desulphurization happens. For further steps, the model was used to simulate the operation optimization, which revealed that doubleaddition is better than single addition when the total volume of flux equals, but that doesn’t mean the more times of addition are better, however, the best addition times could be calculated by the model.

Key words: RH, refining flux, silicon steel, desulphurization process model