Feasibility study on use of Arabic gum as alternative to corn starch in bonding self-reducing briquettes made by integrated cycle by-products

The selection of a suitable binder is crucial to ensure efficient powder agglomeration and high mechanical stability of briquettes. In ironmaking and steelmaking, binders must have low silica, low ash, high environmental sustainability, and compatibility with furnace lining and slag. Gelatinized corn starch has shown good performance with several residues (e.g., jarosite, red mud, mill scale), but it has not provided consistent results when used with integrated steel-plant by-products. This study investigated the possibility of replacing corn starch with Arabic gum, analyzing briquettes produced from basic oxygen furnace dust combined with two reducing agents: blast furnace sludge (BFS) and secondary dust (SD). Arabic gum improved impact resistance index of BFS-containing agglomerates reaching IRI of 1000 (125 with starch), due to better particle arrangement and densification. The resulting lower porosity (34.3 % Vs 39.3 %) enhanced contact between carbon and iron oxides, raising the reduction degree to 90 % (86 % with starch). Moreover, the denser microstructure limited the swelling phenomenon observed in starch-bound briquettes during thermal treatment. In contrast, the use of SD as the reducing agent resulted in a coarser particle size, leading to a heterogeneous distribution during the mixing process with Arabic gum. This corresponded to a decrease in mechanical stability, with the briquettes surviving 5 drops compared to 10 with starch. Despite this drawback, the degree of reduction remained largely unaffected at 1200 °C.