Phase chemistry study of products from the vitrification processes AshArc and Deglor

Abstract

AshArc and Deglor are two new complementary vitrification processes for residues from incineration of municipal solid waste. The hazardous fly ash and bottom ash are converted into a glassy product (main product), a heavy metal salt fraction, a metal fraction (AshArc only) and an off-gas. AshArc is a reductive melting process based on DC arc furnace technology, whereas the Deglor process is based on a glass tank furnace with a more oxidizing gas atmosphere. Samples from pilot and technical scale Operations of both processes were analyzed in detail using methods from petrography and chemical analysis by electron microprobe and X-ray fluorescence. Both processes produce homogeneous glassy melts with variable amounts of metal-rich minute inclusions. For the reductive AshArc process with a relatively short retention time in the furnace the melt contains a minor fraction of metal and metal sulfide inclusions enriched in iron, copper and lead, as well as traces of chromium spinel. Deglor samples are either free of inclusions or contain traces of metal sulfide enriched in copper, iron, nickel and lead. The residues contain heavy metal concentrations below those stipulated for inert waste materials according to Swiss legislation except for zinc in some samples.