WOCA - Wood Based Carbon Electrodes

Den metallurgiske industrien forbruker store volumer karbonelektroder i produksjonen av f. eks. aluminium, stål og ferro-legeringer. I dag består disse elektrodene av 75-85% kull/koks og 15-25/ kulltjærebek. Kulltjærebeken, som brukes som bindemiddel i elektrodene, inneholder betydelige mengder polyaromatiske hydrokarboner (PAH), og representerer derfor et betydelig helse, miljø- og sikkerhetsproblem for den metallurgiske industrien. Målet for prosjektet Trebaserte Karbon-Elektroder (Wood Based Carbon Electrodes, WOCA) var å utvikle nye, miljøvennlige bindemiddel fra tre, som kunne erstatte dagens fossile tjærebek i produksjonen av karbon-elektroder. Dette ville ha resultert i en betydelig forbedring i produksjonen av metaller ved å eliminere de miljøfarlige utslippene av PAH knyttet til bruken av bindemiddel basert på kulltjærebek. I tillegg ville de nye bindemidlene kunne ha resultert i en signifikant reduksjon i CO2-avtrykket til den samme industrien. Prosjektet var en fortsettelse av NFR BIA prosjekt 235148 "Grønne Bindere til Karbonprodukter". I løpet av prosjektet har en rekke tre-baserte bindemiddel blitt produsert og evaluert for mulig bruk i Söderberg- og forbakte karbonelektroder.

Above all, this project has significantly increased interdisciplinary research collaboration between leading Norwegian companies, Elkem and Borregaard. Through this research, a much improved understanding of plant-based binders for carbon materials has been achieved in terms of both potential opportunities and remaining challenges.

The overall goal of the WOCA project is to develop a wood based binder for Søderberg- and pre-baked electrodes used in the metallurgical industry. Today these electrode materials constitute 75-85% coal/coke and 15-25% coal tar pitch. The pitch, which serves as the current binder, contains almost pure PAH (poly aromatic hydrocarbons) which is a major health and working environment problem, as well as an emission problem for the metal industry. Moreover, the EU has signalled that coal tar pitch will be put under more strict REACH regulations, categorizing it as a substance of very high concern. Thus, it is of utmost importance to find environmentally friendly, PAH-free alternatives. The project is a continuation of the NFR BIA project 235148 "Green Binder for Carbon Products". Through this project significant progress towards a bio-binder has been made, and an environmentally friendly binder that can be used to produce pre-baked electrodes of quality close to those prepared with coal tar pitch has been developed. However, the results obtained did not provide a conclusion on all criteria with respect to use of the green binder in commercial electrodes, and more research is needed, in particular with focus on reactivity of the resulting electrodes in an operational environment. Successful implementation of the use of wood based binders in Søderberg- and pre-baked carbon electrodes will significantly reduce the CO2 footprint and improve health, environment and security(HES)aspects for the metallurgic industry.