AISI/DOE Technology Roadmap Program: Removal of Residual Elements in the Steel Ladle by a Combination of Top Slag and Deep Injection Practice.

摘要

The objective of this work was to determine if tin could be removed from liquid steel by a combination of deep injection of calcium and a reducing top-slag practice. The work was carried out in three stages: injection of Ca wire into 35 Kg heats in an induction furnace under labortory condition; a fundamental study of the solubility of Sn in the slag as a function of oxygen potential, temperature and slag composition; and, two full-scal plant trials. During the first stage, it was found that 7 to 50% of the Sn was removed from initial Sn contents of 0.1%, using 8 to 16 Kg of colcium per tonne of steel. The Sn solubility sutdy suggested that low oxygen ptoential, high basicity of the slag and lower temperture would aid Sn removal by deep injection of Ca in the bath. However, two full-scale trials at the LMF station in Dofasco's plant showed vitually no Sn removal, mainly because of very low Ca consumption rtes used (0.5 to 1.1 Kg/tonne vs. 8 to 16 Kg/tonne used during the induction furnace study in the labortory). Based on the current price of Ca, addition of 8 to 16 Kg/yonne of steel to remove Sn is too cost prohibitive, and therefore, it is not worthwhile to pursue this process further, even though it may be technically feasibile.