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<p>Industrial fayalite slags have complex chemistry, but understanding the properties of slags representing fundamental FeO<sub>x</sub>-SiO<sub>2</sub> system is important for advancing slag engineering, developing freeze-lining concepts and next-generation Cr-free refractories, and in slag valorization. In this work, synthetic copper slags with Fe/SiO<sub>2</sub> ratios of 1.5, 2.0 and 2.3 were produced using the method of melting the Fe<sub>2</sub>O<sub>3</sub>+SiO<sub>2</sub> mixture in a graphite crucible at 1280&#xa0;°C. The produced slags consisted of Fe<sub>2</sub>SiO<sub>4</sub> (82.4–100&#xa0;pct) and Fe<sub>3</sub>O<sub>4</sub> (13.9–17.6&#xa0;pct) as confirmed by XRD which well represented industrial slags. SEM/EDS analysis conducted on panoramic images of slags revealed best developed large, columnar fayalite grains with their average size of 366&#xa0;<i>µ</i>m and highest aspect ratio of 7, without free SiO<sub>2</sub> and Fe<sub>3</sub>O<sub>4</sub>, for slag with Fe/SiO<sub>2</sub> of 2.0. Whereas slag with Fe/SiO<sub>2</sub> ~1.5 and ~2.3 additionally form free silica and free magnetite in slag volume, respectively, which would diminish freeze-lining integrity or cause silica penetration to refractory easier. All slags showed partial fayalite oxidation from SEM images. Increased oxygen activity during slag cooling also produced Fe<sub>3</sub>O<sub>4</sub> layer at slag surfaces, with its thickness increased with higher Fe/SiO<sub>2</sub> in slag. Fe<sup>2+</sup>/Fe<sup>3+</sup> in slags were reduced with higher Fe/SiO<sub>2</sub> of 32.3 (S1.5), 4.3 (S2.0), 3.5 (S2.3). The peak shift in energy scale for Si K edge XAS spectra of SiO<sub>2</sub> in fayalite slags indicated reduced polymerization degree with higher Fe/SiO<sub>2</sub>.</p>

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Preparation and Properties of Fayalite (Fe2SiO4) Synthetic Copper Slags with Fe/SiO2 Ratios from 1.5 to 2.3

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  • 发表日期：

    2025年10月24日

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  • Ilona Jastrzębska

摘要

Industrial fayalite slags have complex chemistry, but understanding the properties of slags representing fundamental FeOx-SiO2 system is important for advancing slag engineering, developing freeze-lining concepts and next-generation Cr-free refractories, and in slag valorization. In this work, synthetic copper slags with Fe/SiO2 ratios of 1.5, 2.0 and 2.3 were produced using the method of melting the Fe2O3+SiO2 mixture in a graphite crucible at 1280 °C. The produced slags consisted of Fe2SiO4 (82.4–100 pct) and Fe3O4 (13.9–17.6 pct) as confirmed by XRD which well represented industrial slags. SEM/EDS analysis conducted on panoramic images of slags revealed best developed large, columnar fayalite grains with their average size of 366 µm and highest aspect ratio of 7, without free SiO2 and Fe3O4, for slag with Fe/SiO2 of 2.0. Whereas slag with Fe/SiO2 ~1.5 and ~2.3 additionally form free silica and free magnetite in slag volume, respectively, which would diminish freeze-lining integrity or cause silica penetration to refractory easier. All slags showed partial fayalite oxidation from SEM images. Increased oxygen activity during slag cooling also produced Fe3O4 layer at slag surfaces, with its thickness increased with higher Fe/SiO2 in slag. Fe2+/Fe3+ in slags were reduced with higher Fe/SiO2 of 32.3 (S1.5), 4.3 (S2.0), 3.5 (S2.3). The peak shift in energy scale for Si K edge XAS spectra of SiO2 in fayalite slags indicated reduced polymerization degree with higher Fe/SiO2.