Charcoal and Use of Green Binder for Use in Carbon Anodes in the Aluminium Industry

Carbon anodes for aluminium production are produced from calcined petroleum coke (CPC), recycled anode butts and coal tar pitch (CTP). The CO₂ produced during anode consumption contributes to a substantial amount of the CO₂ footprint of this industrial process. Charcoal from wood has been suggested to partly replace coke in anodes but high porosity, low electrical resistivity and high ash content contributes negatively to final anode properties. In this work, charcoal from Siberian larch and spruce was produced by heat treatment to 800, 1200 and 1400 ℃ and acid-washed with H₂SO₄. Acid-washing resulted in reduced metal impurity and the porosity decreased with increasing heat treatment. Pilot anodes were made from CTP, CPC with some additions of spruce and larch charcoal. Another set of pilot anodes were produced using a green binder. Compared to reference anodes, the CO₂ reactivity of anodes containing larch was less affected compared to anodes containing spruce. The green binder was found to be highly detrimental for the anodes’ CO₂ reactivity properties. Electrochemical consumption increased for anodes containing both green binder, larch and spruce compared to the reference anode.