Abstract: In this paper, the desulfurization mechanism and the role of the passivation lime in the hot metal desulphurization by compound injection were analyzed. According to the production practice of the 80 t hot metal desulphurization by compound injection in TISCO, the passivation lime could be helpful for improving the utilization rate and the desulfurization rate, strengthening the deep desulfurization ability, decreasing the temperature loss, the resulfurization content and the iron loss, and reducing the cost of desulfurization in the hot metal desulphurization process by compound injection. When initial sulphur contends in the hot metal was 0.02 %~0.03 % and the final sulphur contends was less than 0.003 %, compared with the single injection of magnesium grains, the desulfurizer cost of the compound injection was lower by 2.96 yuan/t. The iron loss was lower by 1.08 yuan/t. The slag skimming cost decreased by 0.23 yuan/t. The desulfurization cost was lower by 4.02 yuan/t totally.

Key words: hot metal desulfurization, compound injection, passivation lime