Facemasks and ferrous metallurgy: improving gasification reactivity of low-volatile coals using waste COVID-19 facemasks for ironmaking application

The global pandemic response to COVID-19 has led to the generation of huge volumes of unrecyclable plastic waste from single use disposable face coverings. Rotary hearth furnaces can be used to recover Zn and Fe from non-recyclable steelmaking by-product dusts, and waste plastic material such as facemasks could be utilized as a supplementary reductant for the rotary hearth furnace (RHF), but their fibrous form makes milling and processing to appropriate sizing for RHF application extremely challenging. A scalable method of grinding facemasks to powder by melting and mixing with Welsh coal dust reported herein provides a solution to both environmental challenges. The melt-blended PPE/coal dust shows a dramatically improved CO2 gasification reactivity (E-a = 133-159 kJmol(-1)) when compared to the untreated coal (E-a = 183-246 kJmol(-1)), because of improved pore development in the coal during the pyrolysis stage of heating and the catalytic activity of the CaO based ash present in the facemask plastic. The results are promising for the application of waste facemasks in recycling steelmaking by-product dusts in rotary hearth furnaces and may also be suitable for direct injection to the blast furnace subject to further study.

Automated summary

The global pandemic has caused a massive amount of unrecyclable plastic waste, especially from single use face masks. This study proposes a method of melting and mixing face masks with coal dust to create powder, addressing the environmental challenges. The results show that the melt-blended mask/coal dust material exhibits high CO2 gasification reactivity, suggesting its potential use in recycling steelmaking by-product dusts or direct injection to blast furnaces.