Laboratory Study on the Sintering Behavior of Zircon‐Based Ladle Filler Sands

Abstract

To understand the sintering behavior of zircon-based filler sands, laboratory experiments are conducted, and the effect of steel grades containing different contents of Mn and Al is studied. The results show that zircon filler sands have a sufficient sintering performance without the influence of steel. The reaction between the mullite grains and the decomposed zircon grains results in the formation of a liquid phase, making the sand grains bond. Liquid steel (even liquid pure iron) evidently impacts the sintering of zircon filler sands. Similar to chromite filler sands, the effect of Mn in liquid steel on the sintering of zircon filler sands is also remarkable, whereas the effect of Al (up to 250 ppm) is not so profound due to the existence of the mullite grains. In most cases of conventional Al-killed steel grades (Al ≤ 300 ppm), zircon-based filler sands show a sufficient sintering effect, whereas they are not suitable for high-Mn and high-Al steel grades due to the serious sintering result.

Effect of zircon addition on the sintering of chromite-based ladle filler sands

“…As shown in Figure 2, the mixed filler sands of FS1-FS4 become denser and denser with the increasing addition of zircon grains. The liquid ratio shown in Figure 3 As reported [16][17][18], zircon grains can be decomposed into zirconia and SiO 2 at steelmaking temperature. The generated SiO 2 will further react with chromite grains to form liquid phase.…”

“…The elemental mappings of the boundary between chromite and zircon grains are given in Figure 4. It is seen from Figure 4 that similar to zircon filler sands [16], the zircon grains in the mixed filler sands are decomposed into zirconia particles (Z) as well, and a liquid phase (L) is generated at the boundary between the grains. The main components of the In order to further analyze the formation of liquid phase, the specific compositions of the liquid phase in the sintered filler sands are listed in Table 4.…”

“…Meanwhile, the activity of Fe is unity, and the activity of Mn can be calculated by the dilute solution model. The interaction coefficients can be found in a previous publication [16]. Since there is no MnO in the liquid phase in the beginning, the MnO activity should be 0.…”

“…People believed that zircon is an ideal material for filler sands. On this basis, Deng et al [16] studied the sintering mechanism of zircon-based filler sands, and discussed their application possibility in the production of high Mnhigh Al steel grades. The results showed that zircon grains decomposed into zirconia and SiO 2 , and SiO 2 reacted with mullite grains in the sands to form liquid phase.…”

“…Zircon grains are chemically stable and round in shape. Besides, they also have the advantages of large specific gravity, low thermal expansion rate and low thermal conductivity as well as strong resistance to steel penetration [15,16]. People believed that zircon is an ideal material for filler sands.…”