THE FUNDAMENTALS OF USING CUSTOM-DESIGNED SLAGS TO REMOVE IMPURITIES FROM LIQUID STEEL

摘要

The increasing demand for clean steels low in residual elements has necessitated the improvement of the existing refining procedures. As a result, steel refining has spread into different vessels and new processing techniques have been developed in order to improve both quality and productivity. In this paper, the fundamentals of using custom-designed slags to remove impurities from liquid steel are reviewed. The capacities of various species in molten slags are discussed using the traditional method of empirical ratios and optical basicity to describe slag basicity. The capacities discussed are those for phosphorus, sulfur, water vapour and nitrogen, and inis shown that the use of optical basicity avoids some of the confusion arising from the use of empirical ratios, particularly with regard to the effect of magnesia, and thus facilitates the designing of slags with appropriate characteristics and properties for the post furnace treatment of steel.