Interaction Between Mineral Phases in a Goethitic Iron Ore and Fluxing Materials During Sintering

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Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science


The interaction between the minerals in a goethitic iron ore (goethite, quartz, hydrohematite, quartz-dispersed hydrohematite, and quartz-dispersed goethite) and pure flux materials (CaO, MgO, SiO , and Al O ) was studied by heating ore–flux interaction couples to different temperatures under 0.5 kPa O partial pressure when the samples were loaded into the hot zone of a furnace preheated to 1300 °C. The results show that CaO was the most effective flux for liquid-phase generation during sintering. MgO diffused into ore grains by solid-state diffusion and formed solid solution (Fe, Mg)O·Fe O , but did not generate liquid. Al O and SiO in the interaction couples were relatively inert during heating. The goethite matrix, as the major mineral phase of the ore, played a key role in the interaction with CaO. At 1200 °C, no apparent liquid formation was observed. CaO diffused into the goethite matrix, and first reacted with SiO to form CaO·(SiO ) . Then CaO combined with Fe O and formed CaO·(Fe O ) . When heated to 1225 °C, CaO·(Fe O ) and CaO·(Fe O ) ·(SiO ) phases formed by solid-state reaction started to melt. With increasing temperature, more liquid phase was generated. Whole ore particles were almost completely assimilated, with only a few dense ore fragments being observed in the samples heated to 1300 °C. Other mineral phases in the goethitic ore were less reactive due to their dense structure. On heating during sintering, dehydration of goethite generated a porous structure and cracks in the ore body, facilitating the diffusion of flux and penetration of flux-containing liquid phase. The core particles in the ore body, including hydrohematite minerals, remained relatively dense and so their assimilation during sintering is slow. 2 2 3 2 2 3 2 3 2 2 2 x 2 3 2 3 x 2 3 x 2 3 x 2 y

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