High-temperature performance evolution and consolidation mechanism of zinc-bearing iron dust-mud agglomerates

Eight types of zinc-bearing iron dust and sludge generated from iron and steel production processes were used as main raw materials, and agglomerates were prepared by adding different types of binders. Under simulated rotary hearth furnace process conditions, the evolution law and influence mechanism of compressive strength of agglomerates during the roasting-reduction process were systematically investigated. Results indicated that inorganic binders could effectively stabilize the initial structure of agglomerates and promote the formation of low-melting-point compounds, thereby improving the compactness and high-temperature compressive strength of agglomerates(the high-temperature strength could reach 3 309 N at 1 250 ℃). However, the agglomerates pre-pared with inorganic binders exhibited poor room-temperature performance with a strength of only 331 N, and the gangue components introduced by binders would reduce the iron grade of agglomerates. Agglomerates prepared with organic binders showed excellent room-temperature performance, with the room-temperature compressive strength reaching 467 N. Nevertheless, intense pyrolysis reactions of organic components occurred during high-temperature roasting, leading to a significant increase in the porosity inside the roasted agglomerates and a substantial decrease in high-temperature compressive strength. Composite binders efficiently connected the key links of low-temperature strength maintenance and high-temperature strength regeneration of agglomerates, effectively alleviated the expansion phenomenon during the reduction process, significantly improved the compactness and overall strength of agglomerates throughout the whole roasting-reduction cycle, and thus demonstrated excellent potential for comprehensive application.