5th International High Manganese Steel Conference - HMNS 2022

Product quality, throughput, as well as energy and resource efficiency are the most important requirements in steel production. In order to meet these requirements, typically more than 15 parameters such as temperature, energy consumption and composition of the steel are monitored and the process is adjusted accordingly. The slag analysis results however, are due to extensive homogenization times only available 10 to 30 minutes after sampling. Therefore the results are evaluated post-mortem for following heats.

This "slag pathology" is particularly dramatic, since the slag analysis allows comprehensive conclusions on the process condition and is correspondingly valuable for process control. Insufficient slag composition can lead to increased refractory wear, greater oxidation of alloying agents such as Mn and other unbeneficial effects. Especially the loss of valuable alloying elements is problematic in multiple ways. They have to be purchased at high cost, melted down energy intensively, and then be disposed in a costly and time-consuming manner.

Various workarounds have been established to estimate or guess the slag composition, but none of them can compete with chemical analysis in terms of precision.

Laser Optical Emission Spectrometry (Laser OES) is increasingly establishing itself as an alternative. Due to up to 1.000 measurements per second it can homogenize data instead of physical samples. this allows a significant acceleration of the overall slag analysis time from the hot sample to the result down to 1-2 minutes. Along with an increased number of samples analyzed per heat, this enables a close monitoring as well as an in-situ process adjustment based on real analysis results.

A precise furnace control in a narrow process window close to the targeted optimum reduces the refractory wear, it minimizes the oxidation of alloying agents such as Mn into the slag and it improves energy efficiency.