Intelligent cleanness controls in secondary steelmaking by advanced off- and online process models (INTCLEANCON) : final report

During this collaborative project between TECNALIA, GERDAU, BFI and DEW, the consortium has achieved the development of new off-line and on-line models for advanced control strategies in secondary metallurgy, in order to guarantee highest steel cleanness levels for high quality steels, with focus on final product cleanness case hardening steels and castability on microalloyed grades. For the case of GERDAU, a new castability index has been developed as the main measurement index of the project success. Regarding LF treatment the electrical parameters have been analysed in order to study the influential parameters on the electrical stability to correlate it with the bath stirring. This bath stirring has been studied by a CFD simulation tool for deep analysis on the influence of stirring rates on the free surface behaviour and also on the separation rates achieved on the vacuum degasser. For the ladle treatment process route of DEW a prediction model for a cleanness indicator was developed via a multi-linear regression analysis of relevant operational parameters. With the help of mathematical and physical modelling, information on optimum gas flow rate and stirring time was provided with regard to an operational window for the soft bubbling stirring process. An image-based online monitoring and control system for the stirring intensity was installed at the final treatment station. With this system also the result of the online prediction model for steel cleanness is displayed. It provides the operator with information on the required stirring intensity and duration and allows achieving optimum results with regard to steel cleanness. These new control strategies have a direct impact on the product rejection, it is the consequence of an improvement in process efficiency that directly produces a noticeable economic benefit and some other benefits more difficult to translate into Euros but important too