ORALS

SESSION: CarbonTueAM-R7	6th Intl. Symp. on Sustainable Carbon and Biocoke and their Industrial Application
Tue. 28 Nov. 2023 / Room: Sunflower
Session Chairs: David Scheiblehner; Gustav Hanke; Session Monitor: TBA

11:35: [CarbonTueAM01] OS Plenary
OPTIMIZATION OF BIOCOKE FOR ITS USE IN METALLURGY
Gustav Hanke¹ ; Juergen Antrekowitsch² ; Christian Dornig¹ ; ¹Montanuniversität Leoben, Leoben, Austria; ²Christian Doppler Laboratory, Leoben, Austria;
Paper Id: 112 [Abstract]

Despite all modern technologies and innovative developments, carbon is still of major importance in metallurgy. Not only for iron and steel production, but also for nonferrous metals. In many pyrometallurgical processes, coal and coke are the main reducing agents and important energy sources. However, one product of carbon application is always CO2, which is known as one major problem in climate change. As such, it is indispensable to develop and use new sustainable technologies that reduce or eliminate the CO2 discharge to the atmosphere. In metal production, carbon is still the most important reducing agent and essential for most modern pyrometallurgical processes, and this will not change in near future. In the short- and mid-term, until entirely new processes that are not carbon-based are introduced, the use of coke out of biomass can help to minimize the CO2 footprint. However, coke must meet several requirements in terms of reactivity, stability, grain size, etc. to be used in specific processes. Here, the influence on the process caused by the much higher reactivity and different impurities needs to be studied and defined, to optimize existing treatment procedures, if necessary.For replacing fossil coke, which is in use today, the coke produced out of biomass must be as similar as possible so that in best case, no changes in the processes are necessary.For an environment-friendlier solution, the origin of the biomass is also critical. Preferably, the material is locally available and not of any other use. Depending on the location, this could be agricultural residues like olive stones and fruit tree cuttings or waste wood for example.Until now, the use of biocoke in lead production and in the Waelz kiln was in the focus of research at Montanuniversitaet Leoben. While the application in lead metallurgy is less problematic and was tested successfully, the substitution of coke in the Waelz kiln is more difficult and places higher demands on the properties of the carbon carrier, especially in terms of reactivity. For this, the reduction of reactivity is now in focus and will be critical for the future of biocoke in this process. Trials showed that an increase of the grainsize (pellets) and a treatment with additives like bentonite, has a positive impact on the properties of the coke and could lead to an efficient application.

SESSION: RecyclingTuePM1-R7	9th Intl. Symp. on Sustainable Materials Recycling Processes & Products
Tue. 28 Nov. 2023 / Room: Sunflower
Session Chairs: Florian Kongoli; Juergen Antrekowitsch; Session Monitor: TBA

14:05: [RecyclingTuePM105] OS Plenary
ZERO WASTE PROCESSING OF ZINC CONTAINING SLAGS FROM LEAD INDUSTRY
Juergen Antrekowitsch¹ ; ¹Christian Doppler Laboratory, Leoben, Austria;
Paper Id: 368 [Abstract]

Slags from primary lead industry are well known as potential resource for zinc which is accumulated in the slag during lead smelting. At some of the smelters a subsequent fuming process is installed to recover zinc which is usually present in a range between 4 to 16 %.However, at many lead producers this is not the case and the slag is landfilled. Out of this, over the years, a huge number of dumps was generated worldwide. The Chair of Nonferrous Metallurgy at Montanuniverstaet Leoben has developed possible strategies to treat such slags in a way that zinc and lead can be recovered and the remaining mineral phase containing first of all typical slag components can also be utilized. These concepts allow a full remediation of a dumpsite or a zero waste treatment of slag from ongoing smelter operations.The present paper describes the reduction process which is performed under CO2-neutral conditions, utilizing either hydrogen or charcoal. Furthermore, possibilities for slag modification and optimization are explained, allowing a utilization of the slag in building and construction industry. Results from various test campaigns in lab- and technical scale are discussed.Finally, an overview of the worldwide potential and some process scenarios including economic considerations are presented.

References:
[1] Auer M., C. Wölfler and J. Antrekowitsch: Inflluence of different carbon content on reduction of zinc oxide via metal bath. Applied Sciences (2022), 12, 2, 4180
[2] Hanke G., J. Antrekowitsch, F. Castro and H. Krug: Maximizing the efficiency of by-product treatment by multi-metal recovery and slag valorization. Rewas 2022 – Developing tomorrow‘s technical cycles (2022), Anaheim, Kalifornien, USA, 201–211
[3] Leuchtenmueller M., C. Legerer, U. Brandner U. and J. Antrekowitsch: Carbothermic Reduction of Zinc Containing Industrial Wastes: A Kinetic Model, Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science (2021), 548-557