Influences of SO₂ in the Recirculation Flue Gas on the Iron Ore Sintering Process

Abstract

The influences of SO₂ in the recirculation flue gas on the sintering process are studied through simulating the flue gas recirculation with sinter pot test at room temperature. The results show that, with the increasing concentration of SO₂, the SO₂ is absorbed by CaO, the surface of CaO particles will generate CaSO₄ which affects the formation of binding phase, so the sinter yield and particle size will decrease. The residual sulfur in sinter ore will increase obviously when SO₂ concentration is higher than 500 ppm, the residual sulfur of middle sinter ore in 2000 ppm is 1.54 times higher than that in 500 ppm. Meanwhile, the SO₂ peak concentration in flue gas is enriched, which is conductive for the end-of-pipe treatment of SO₂. The RI of sinter ore is increased and softening and melting properties become better, because the consumption of CaO affects the formation of calcium ferrite and increases the reduction rate and melting point of sinter ore, another reason is that the decomposition of CaSO₄ leads to an increase in the porosity in the sinter, and the higher porosity makes the sinter expose more surface area to the reduced body, and the RI of the sinter increase. Therefore, adding an appropriate amount of SO₂ in the sintering process can improve the quality of the sinter, and if the SO₂ content is too high, it will affect the formation of the binder phase and reduce the strength and yield of the sinter.