Especially zinc oxide is one main product from the treatment of complex residues. Mostly it is collected in the off-gas stream but accompanied by different volatile compounds, which partly form harmful impurities in the product. Investigations on the quality increase, getting rid of the halides by pyro as well as hydrometallurgical methods, are one special focus of this research work. Not only the behavior of these compounds but also the interaction between them, especially in the case of pyrometallurgical treatments, is of major interest, which is why it is studied in detail. One aim is to figure out what qualities are possible to achieve under economic considerations and if the produced zinc oxide meets the requirements to break into alternative markets, such as the galvanizing, zinc sulphate or zinc oxide markets in addition to its established utilization as a secondary source as an ore-substitute in the primary zinc industry.
A very special topic in this research field is the utilization of solar power to increase the energy efficiency of these purification processes. This area is carried out together with the well-known Paul Scherrer Institute located in Switzerland.
The steam reforming to oxidize metallic zinc to ZnO is also investigated. The advantage of H2O as an oxidation agent instead of air (the most common way) is the generation of H2, a possible reducing agent in different metallurgical processes.
Product quality plays an important role in most of the recycling processes from the economic standpoint. It is often still not investigated sufficiently, and as a result these products have to undergo a complex and energy-intensive treatment until they find their way into the consumer market.