Dr. Juergen Antrekowitsch

Abstract:

The use of biocoke in metallurgical processes to reduce the carbon footprint of metal production has gained significant traction in recent years. This trend is particularly evident in Central Europe, where biocoke production has grown rapidly. While utilization of biocoke has already become standard in certain processes, such as ferroalloy production, its implementation in other metallurgical routes remains challenging [1].

Key limitations include its high surface area and reactivity, low mechanical strength, and low bulk density. These properties often make even partial substitution of fossil carbon infeasible - especially in systems like rotary kilns, small shaft furnaces or vertical retorts. In such setups, the reducing agent undergoes a pre-heating phase and ideally remains inert for one to two hours before entering the reduction zone. Under these conditions, conventional biocoke is ineffective [1, 2].

At the Chair of Nonferrous Metallurgy, Technical University of Leoben, new strategies have been developed to tailor the properties of pyrolyzed biomass for metallurgical use. Through advanced micro-granulation combined with small quantities of special additives, reactivity can be reduced by at least 50%. This treatment also enhances density and improves performance in possible subsequent agglomeration processes such as briquetting.

This presentation highlights the described optimization steps, which are currently the subject of a patent application. It also presents results from the investigation in various additives and discusses initial implementation trials in advanced lab-scale vertical retorts, shaft furnaces, and rotary kilns focusing on different metal recycling processes in the field of zinc, copper and lead containing resources. Finally, the entire production chain for optimized biocoke is evaluated using different woody biomass feedstocks.