Characterization of industrial hydrocarbon samples from anode baking furnace off-gas treatment facility

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are naturally present in raw materials used as a binder in prebaked anodes for electrolysis of aluminum. Green anodes are baked to about 1200 °C through a cycle of 14–17 days where organic hydrocarbon volatiles contribute to the carbonization process. Off-gases contain volatile and semi-volatile organic components, which are further treated to reduce environmental emissions by techniques such as regenerative thermal oxidizers and dry or wet scrubbers. Still, prebaked anode production contributes to a noticeable part of the reported PAH emissions in Norway. Samples of condensed hydrocarbon-based residues have been collected from an off-gas treatment facility and a set of analytical methods applied to determine the presence of different categories of aromatic hydrocarbons in these samples. Based on the results of the characterization, it was determined that the residue contains sulfur-substituted and polar aromatic hydrocarbons in addition to the PAH-16 routinely reported. It was concluded that future research should be dedicated to extending the range of PAHs that can be reliably determined, with particular emphasis on substituted species.