A study on the new approach for refining molten steel using a used reductive slag

Refining is essential to stjel making; to which, obtaining a reductive slag is critically important to the process. The reductive slag could help to remove impurities in molten steel, to adjust compositions of the steel, and to protect the molten steel from oxidation. Currently, all the electric furnace steel plants in Taiwan employed ladle furnace process for refining their molten steel. The reductive slag in ladle furnace is used only once. This not only increases the cost of steel making but is also harmful to the environment. This study focuses on the question of whether or not the reductive slag can be reused for next refining process in ladle furnace, Here, steel melting and refining were carried out in a bench-scale furnace. CaO-based slag was used for present study. Experimental results show that new CaO-based slag can effectively reduce the sulfur content in molten steel in 30 minutes. The used slag (i.e., post-desulfurized slag) was again to be applied for the next refining process. Chemical analysis confirms that the used slag was still able to reduce the sulfur content in the molten steel from 0.05 wt.% of S to lower than 0.03 wt.% of S in 35 minutes. XRF analysis results show that the basicity of the used slug was still larger then 2, supporting that the used reductive slag should be reused for refining.