Approximately 20 kg of dust and sludges are produced per ton of liquid steel produced via the blast furnaces (BF)/basic oxygen furnace (BOF) production route. Many of these dusts are recycled through the sinter plant or blast furnace route without issue, but high zinc content dusts are routinely landfilled. Hydrometallurgical techniques, such as alkaline leaching, that are often utilized to remove zinc from electric arc furnace dusts are inappropriate for recovery of material from BOS dust due to the lower zinc concentration present and extra post-processing steps to utilize the separated iron product. Pyrometallurgical treatment through a rotary hearth furnace (RHF), in processes such as FASTMET ® , can currently be considered as the most commercially attractive option for the processing and recovery of iron and zinc units when employed as part of an integrated steelworks. The crude zinc oxide produced is suitable for sale to zinc smelters, and the direct reduced iron produced provides process benefits through use, such as reduced blast furnace coking rates and increased productivity. The advantages and disadvantages of variations and alternatives are reviewed with regard to future developments.

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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 (Ea = 133–159 kJmol−1) when compared to the untreated coal (Ea = 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.