Recycling spent refractories can reduce reliance on raw material imports, yet challenges such as separating different refractory types and removing impurities persist. This study examines sensor-based detection of elemental carbon and metal impurities in spent refractory bricks, detailing the fundamentals of refractories and the current recycling landscape. Eight refractory types, prevalent in the steel industry, were analyzed using four sample types, with their preparation outlined. Various physical properties were measured to identify suitable features for detecting impurities. Two key features emerged: induction and microwave heating behavior, both of which are discussed alongside theoretical backgrounds, test setups, and results. Findings indicate that microwave heating can effectively identify elemental carbon, albeit with limitations, while induction is effective only for presorted fractions. A new process is proposed, integrating existing LIBS technology with microwave heating and induction. Current recycling methods require enhancement to comply with stringent quality standards and boost recycled refractory quantities. The study demonstrates that employing inductive sensors and microwave heating can significantly improve the sorting of spent refractories.
