The chemical suitability for recycling of zinc contaminated steelmaking by-product dusts: The case of the UK steel plant

Basic oxygen steelmaking (BOS) dust and blast furnace (BF) dust from former and operating steelmaking facilities in the United Kingdom have been characterized by MP-AES, SEM-EDX, particle size analysis, TGA-DSC, combustion analysis, 57Fe Mössbauer spectroscopy, and powder XRD. These materials are a potentially valuable source of Fe for ironmaking, but their contamination with zinc precludes their recycling via the conventional sinter plant/BF route. XRD suggested some of the zinc present in the material is in the form of sub-stoichiometric zinc ferrites ZnxFe3-xO4, making hydrometallurgical separation less effective. BF dust contains 40 wt.% levels of fixed carbon (Cfix) indicating it could be useful as an alternative reductant in rotary hearth furnace processes such as FASTMET. The rotary hearth furnace appears to be the most suited separation technique available due to its lack of sensitivity to zinc present in zinc ferrite compounds, and reintegration of the recovered iron into the steelmaking process.