Control of inclusion, slag foaming and temperature in vacuum degassing

This work is carried out by five partners within the frame of the ECSC's research program. The partners were: - ABS - SIDENOR - OVAKO - BFI - MEFOS Two similar vacuum concepts are concerned, Vacuum Degassing and ASEA-SKF.In the VD-process the ladle is placed in a sealed tank while in the ASEA-SKF process the ladle is sealed directly by a gas tight cover. In both processes argon is led through the melt and hydrogen, nitrogen and other solute gases are removed from the steel during efficient mixing between steel and slag. Essential is that the process is operated under stable conditions with predictable metallurgical results. The project has been focusing on three different subjects: - Improved temperature control - Real time inclusion control - Methods to avoid severe slag foaming As a result of the work, a previously developed real time process control model has been extended with new and improved functionality. The realisation of the models follows principally the same strategy for all three subjects, including: - Assessment and analysis of operation at the three participating steel plants. - Adaptation and test of new systems for measurement and supervision on sites. - Evaluation of measurements and production data by development of new CFD models. - Development of real time process models based on CFD results and production data. - Verification of the process models in production. The work was organised as sub-projects in parallel during the project time of three years, June 1998 to June 2001, Figure 1. In the same figure the split of responsibility between the partners is indicated.