Alumina Pick up by Mould Slag During Continuous Casting of Steels

摘要

Mould powders are used during continuous casting of steels for pre-defined purposes;and the powder melts to form a slag which is responsible for mould lubrication, among other things. The extent of lubrication provided depends on the amount of slag pool generated and the viscosity of the slag. Alumina inclusions present in liquid steel should be removed as much as possible during the continuous casting process. In some cases, the alumina pick up by the mould slag may be so significant that the composition and properties of the slag are significantly different from the initial condition. In such cases, slag induced sticker breakout may occur, resulting in a serious problem in operations. Efforts have been made to understand and control these reactions. In the present work, thermodynamic analysis - using ThermoCalc software and related databases - has been performed, to understand the conditions under which crystalline precipitates start forming within the mould slag film. Calculations have been carried out considering different indicative lime to silica ratios for mould powders;and the observations summarized. It is expected that this work will facilitate reduction of slag induced sticker breakouts in continuous casting.