Fluorine-Free Mould Powders for Billet Casting - Technological Parameters and Industrial Tests

There is a clear trend in industry to eliminate fluorine from metallurgical slags. Regarding the continuous casting process, fluorine in mould powders is undesirable due to the following reasons: (i) evolves easily from slags producing health‐injurious gaseous substances like hydrofluoric acid, (ii) creates problems for storage and utilization of solid waste, and (iii) causes machinery corrosion. A collaboration among universities, mould powder supplier, and steel producer was established, aiming for the development of a new F‐free mould powder for billet casting. Firstly, technological parameters for a particular composition were determined: melting characteristics, viscosity, melting behavior, and crystallization tendency. Afterwards, industrial trials were performed in a Brazilian steelworks, doing some evaluations during the continuous casting process, such as ΔT between water cooling inlet and outlet, slag pool thickness, melting performance, powder consumption, Al2O3 pick‐up, and effect on SEN erosion. Comparable surface quality for the billets was obtained when using the F‐free mould powder, since the amount of scrap produced during the rolling process was not critical. To develop a new F‐free mould powder for billet casting a collaboration among universities, mould powder supplier, and steel producer was established. For this new mould powder technological parameters were determined and industrial trials were performed in a Brazilian steelworks. Comparable surface quality for the billets was obtained and a significant reduction of SEN erosion was registered.