High-tech carbon-based materials are considered difficult to recycle. A new research approach could change that while also helping to recover metals.
They are used in airplanes, car bodies, wind turbine rotor blades, as well as bicycle frames and tennis rackets: materials based on carbon fibers. These high-tech materials are becoming increasingly widespread because they are strong, stiff and very light at the same time. However, their disposal has been a problem up to now. Products with carbon fibers cannot be incinerated in conventional waste incineration plants and may not be landfilled in Germany, but only stored. Approaches to recycling the material are therefore being intensively researched, especially in view of the fact that many wind turbines will be dismantled in the coming years.
The TU Bergakademie Freiberg and the Karlsruhe Institute of Technology (KIT) are demonstrating a sustainable recycling route for old rotor blades and the like: Discarded carbon fibers could be used to recover valuable metals from slags that are left over from smelting. The carbon contained reacts with the iron oxide in the hot slag to form pig iron that could be reused in steel production, explains Ludwig Blenau, a doctoral student at the Institute of Nonferrous Metallurgy and High-Purity Materials at the Bergakademie. Normally, carbon from coals or cokes is used for this type of metal extraction; these fossil raw materials could be replaced proportionally in the future.
Next, the team would like to subject the method to a practical test on a pre-industrial scale.