Abstract
There are a few studies of the desulphurization of molten steel by CaC2 and CaO. In the present study, 200-350gr. of a low carbon steel was melted in a magnesia crucible, deoxidized by aluminum, and then covered the surface of molten steel by powders of CaC2 or CaO as the desulphuriser. The molten steel was reacted with it for 30-40min at 1550-1600°C, and sampled every 5min for the analysis of the sulphur and oxygen.
The results were as follows:
Using CaO only, the sulphur decreased from 0.09% to 0.03% during 15min but then incre- ased with time. The oxygen content of this melt was 0.003% at the initial stage and began to increase in parallel with the sulphur content for lack of the deoxidising power of CaO. By addition of carbon and silicon to the steel, as the oxygen content was retained less than 0.005% throughout the whole process, the flnal sulphur content decreased to 0.01% and hardly increased.
Using CaC2, the sulphur content was dropped from 0.1% to 0.003% within about 15min and continued to decrease little by little. The final sulphur content depended on the initial oxygen content which was contained in molten steel before the desulphurization. The final sulphur content decreased to 0.01% in molten steel of 0.008% of the initial oxygen conteht, and 0.002% in molten steel of 0.002%.
Whenever molten steel which was contained any oxygen content was treated by CaC2, the sulphur content decreased to lower value. Because CaC2 reacted on molten steel as an effective deoxidiser and desulphuriser.
