Isotopic Spiking – An Innovative Method to Trace Non-Metallic Inclusions in Steel

Description

The interest in non-metallic inclusions (NMIs) is steadily increasing since these primarily microscopic particles influence steel properties and impact the process stability. As the steel industry is transforming to lower CO2 emissions, steel cleanness will be a key topic in the next years. Due to the change to higher scrap rates for steel production as well as the implementation of novel techniques for iron making, it is essential to understand the formation and modification of NMIs to evaluate their impact on steel and further ensure high steel qualities. One major focus, therefore, lies on the investigation of the steel/slag/refractory system to identify the origin of NMIs and track their behavior during the steelmaking process. The state-of-the-art method to trace NMIs is the direct addition of rare earth elements, which mark deoxidation products due to a partial reduction. However, by applying this technique, the properties of the NMIs are influenced, and consequently, their actual behavior in the steel/slag/refractory system cannot be depicted. On that account, an innovative tracing technique, isotopic spiking, was tested. Within this approach, the isotopic composition of Mg in the slag was modified by adding MgO, which is enriched in the stable isotope 26Mg. Due to this modified MgO, the isotopic fingerprint is changed to a composition significantly different from natural, terrestrial materials. In consequence, the origin of an NMI can be traced either to a natural source or the modified slag by determining the isotopic ratio 26Mg/24Mg. Inductively coupled plasma – mass spectrometry, a sensitive measurement technique, was used to determine the isotopic composition of NMIs and the slag. The analysis of several NMIs showed that an enrichment of 26Mg was detected at the outer boundaries of heterogeneous NMIs. The detection of this 26Mg spike confirms that steel/slag interactions took place.

Period	4 Jul 2025
Event title	9th International Congress on Science and Technology of Steelmaking 2025 (ICS 2025)
Event type	Conference
Location	Seoul, Korea, Republic ofShow on map
Degree of Recognition	International