Effect of BaSO4 on phase composition and sintering process of iron ore fines

Iron ore containing BaSO4 may have a series of effects on the quality of the sinter and performance of the blast furnace. Thus, the effect mechanism of BaSO4 (0–6.0 mass%) on the compressive strength, mineral composition, and microstructure of the sinter was investigated. The experimental results show that the compressive strength of the sintered samples initially increases and then decreases when the BaSO4 content increases from 0 to 6.0 mass%, reaching a peak value of 12.78 kN with a BaSO4 content of 1.0 mass%. Thermal analysis indicates that BaSO4 initially decomposes to produce BaO at 1468 K in the presence of iron ore. BaO combines with Fe2O3 forming barium ferrite (Ba2Fe6O11), which exists in the sintered sample with a granular form. BaO also dissolves in calcium ferrite and slag to promote the formation of calcium ferrite and barium glass, respectively. The content of needle-like calcium ferrite gradually increases and then decreases with the increase in BaSO4 content. Hematite exists in a plate-like form. The generation of dicalcium ferrite is promoted by increasing the BaSO4 addition from 2.0 to 6.0 mass%.