Secondary raw materials from metal recycling are an important sustainable alternative to primary raw materials. Even rare metals like tungsten, cobalt, niobium, chrome and titanium can be recycled. Metal scrap, however, is usually a mixture: Different metals are present in different alloys, quantities and forms. These mixtures, combined with impurities and melting losses, significantly lower the recycling rate. In addition, the recycling products are often only of poor quality. For many smelting plants, it is therefore uneconomical to process this scrap.
At present, the materials are sorted manually with the aid of classification devices of optical emission spectroscopy or X-ray fluorescence analysis. The “PLUS” process wants to make the sorting process more economical using new technology. The aim is to distinguish more than 20 different alloys within the material groups of high-speed steel, hard metals and titanium. It should be possible to detect and sort small and even very small scrap fractions - in just a few seconds per fraction.
For their industrial pilot plant, Cronimet and the Fraunhofer Institute for Laser Technology ILT are using laser emission spectrometry methods, which can measure the scrap quickly and without contact. However, this only works if the components of the mixed metal scrap are fed and sorted separately. This process is to be automated during the course of the project.
The “PLUS” pilot plant is an automatic sorting plant with separate material feed-in, laser-analytical classification and robotics-based sorting. The process makes it possible to recycle mixed metal scrap economically.
© Fraunhofer ISI 2020