Research for better recycling
More recycling is needed not only for plastics, but also for many other products and materials to limit the global overuse of resources. This applies to metals in electrical appliances or industrial plants as well as sand or gravel in building materials or refractory concretes. Research institutes of the Zuse Society are successfully working for key industries on the more economical use of valuable raw materials.
While legal requirements apply to packaging to increase the proportion of recycling, the interest in more recycling in other sectors depends on economic incentives. This applies, for example, to the desirable raw material bauxite as ore, which is an important basis for refractory materials. The products also known as refractory concretes are used in steelworks, foundries or power stations due to the very high operating temperatures. Access to raw material sources in Asia will presumably not become easier in the future. This increases the attractiveness of recycling in Germany.
However, refractory products are often easily contaminated by the ingress of gases or liquids. "We are therefore investigating what effects certain impurities have on the properties of refractory products and how recipes can be specifically optimised for further processing as recycling materials," explains Christian Dannert of the Research Association for Refractories (FGF - Forschungsgemeinschaft Feuerfest), a member of the Zuse Society.
Fire concretes are cast in molds similar to building concretes. The FGF has already successfully developed methods to measure the effect of impurities on the processing of refractory concretes. An important criterion for the researchers is the determination of electrical charges on particle surfaces in refractory concretes. The more the particles repel each other, the better the refractory concretes can be processed. "With the methods we have developed, we are helping to ensure that a refractory lining can be optimally installed in a foundry," explains Dannert, Head of Research at FGF. In Germany alone, the potential for using recycled bauxite in refractory concretes is several 10,000 tons per year.