Recycling of refractory materials avoids 800 000 tons of CO2

In the European research project ReSoURCE, experts from nine different companies and institutes are working together to develop sustainable solutions for the recycling of refractory materials. The German project partners are primarily providing laser know-how.

Refractory materials withstand high temperatures beyond 1 500°C. They are indispensable for industrial furnaces that produce glass or ceramics, non-ferrous metals and steels, for example. The service life for refractory products ranges from a few days to many years – depending on the materials, the temperature in the melting vessel and other operating parameters. As a result, about 32 million tons of used refractory materials are produced worldwide every year, of which only a fraction is recycled.

The production of refractory materials from primary raw materials causes considerable amounts of CO2, mainly because carbon dioxide has to be removed from carbonate-type raw materials. In addition, the raw materials are largely imported into Europe. This also includes critical raw materials with risky supply chains. These alone are enough reason to reprocess used refractory materials and feed them into a circular economy, as there are currently no significant alternatives to them.

Automatic sorting system using laser technology
“Refractory products are precisely adapted to the customers’ requirements,” explains ReSoURCE project coordinator Alexander Leitner from RHI Magnesita. The optimal composition of the high-temperature resistant materials depends on the intended application, the manufacturing processes, and the related chemical properties of the process media. “This means that our products have very different compositions. Before recycling, we therefore have to separate them as precisely as possible,” Leitner continues.

The project therefore centres on an automatic sorting system for spent refractory materials. A laser unit will be used to identify the constituents of the used material on a conveyor belt without contacting them. The laser technology comes from the medium-sized company Laser Analytical Systems & Automation GmbH (LSA) from Aachen, a spin-off of the Fraunhofer Institute for Laser Technology ILT. Fraunhofer ILT is a pioneer in developing novel applications for laser spectroscopy, including sorting into pure materials for recycling with laser-induced breakdown spectroscopy (LIBS).

“At Fraunhofer ILT, we have already developed an inline measurement technique that performs a direct analysis of metal scrap on a conveyor belt and detects the composition of each piece of scrap,” explains Dr. Cord Fricke-Begemann, Head of the Materials Analysis Group at Fraunhofer ILT. “With this multi-element analysis, we can detect a large number of alloys. We are now transferring the findings to refractory materials.”

To gain greater insight into the project, the public can follow the research up close on a science blog on the project’s website: