Development and application of a process diagnostic system for the desulphurisation process

In an increasingly competitive steel industry, with ever-stricter grade requirements for sulphur, the requirement for improved control and efficiency is increasingly important to reduce process costs. This paper describes an online system that has been developed and implemented at Tata Steel Port Talbot Works, to monitor and report on the desulphurisation process. The aim of the system is to generate an objective report on the process, to highlight all process deviations and issues, and facilitate diagnosis. This diagnosis will improve process control and process efficiency. The desulphurisation process typically uses lime and magnesium to facilitate the removal of sulphur from the hot metal and into the slag where this is removed by a rabble. The process, with a start Hot Metal Sulphur of 0.045 (wt.%) and Aim Sulphur of 0.008 (wt.%) typically uses approximately 100kg magnesium and 300kg lime for a 300T ladle. The main focus of this system has been the development of linguistic outputs. The outputs have been optimised to provide concise and interoperable information to assist the operators to quickly understand the current state of the process. The system has been designed to monitor three areas regarding the desulphurisation process; model setup, process deviation and sample availability. A report is generated every morning, for use by shift and plant managers, highlighting every deviation in the process over the past 24 hours and diagnosis of the exact cause where possible. The report is compiled on an exception basis, only highlighting treatments providing there has been an issue or deviation from expected material usage.