Enhanced reliability in ladle refining processes (VD, VOD and LF) by improved online process monitoring and control (LAREFMON)

The objective of this project was to improve the reliability of vacuum degassing and ladle furnace treatment by joint application of new thermal imaging-based evaluation of stirring efficiency and improved dynamic process models. Enhanced online monitoring and control systems were developed and applied for reliable control and improved performance of the main metallurgical ladle refining processes: VD: A closed-loop control system for stirring gas rates based on thermal imaging and dynamic process modelling was developed and applied at the VD plant of ArcelorMittalRuhrort GmbH. Monitoring of the melt bath surface during VD treatment improved process control and reliability. VOD: Detection of slag slopping for SBQ steel grades and analysis of stirring power during the VCD part based on CCD images were realised at SIYD. Combination of the online tools and a different oxygen introduction pattern in the oxidising process phase led to a slight improvement in decarburisation rates. LF: An objective online stirring observation system based on CCD images as well as a temperature regulation module using a dynamic model and gas flow rate suggestion for operators based on the total oxygen content of the melt were implemented at VASD. The system is beneficial because of its objectivity (achieve sustainable steel quality) and furthermore for safety reasons. Continuous monitoring of the melt bath surface became an essential tool for the operators at ArcelorMittalRuhrort GmbH, Sidenor I+D SA and VASD to improve the stability and quality of the treatment processes and thereby the overall steel production.