Comparative study between coal tar pitch and lower polycyclic aromatic hydrocarbon (PAH) alternative binders for use in taphole clays

Abstract

The use of alternative low polycyclic aromatic hydrocarbon (PAH) binders in taphole clays is essential due to health and environmental concerns associated with PAHs. Binders that could potentially substitute for highly-temperature coal tar pitch (CTPht) or coal tar (CTht) in taphole clays were investigated. These include coal tar pitch blend, low PAH coal tar pitch, petroleum-based binders and wood-based tars from various sources. The binders were characterized according to chemical composition, with an emphasis on the identification of 16-EPA-PAH (well-known carcinogens), as well as rheology and volatilization behaviour. The alternative binders were ranked according to the analytical results, with the coal tar reference binder, CTht, serving as the benchmark. Beechwood tar (Tar-BW) and crude waxy oil (CWO) showed the most favourable results for replacing CTht in taphole clay. Both have higher viscosities than CTht, lower BE-values (indicating lower toxicity), and higher degrees of mass loss over a wider temperature range.