Desulfurization Ability of Blast Furnace Slag Containing High Al2O3 at 1773 K

Abstract

With the consumption of high-quality iron ore resources, the grade of iron ore raw used in the iron making process has gradually decreased. The high aluminum raw materials has led to an increase in the Al2O3 content in the blast furnace slag, which has affected the normal operation of the blast furnace. The activity of the components involved in the desulfurization reaction is an important factor affecting the desulfurization process. In this paper, the effects of B(w(CaO)/w(SiO2)) and w(MgO)/w(Al2O3) on the desulfurization ability of a CaO-SiO2-MgO-Al2O3 quaternary blast furnace slag system were studied by using a double-layer graphite crucible to simulate the process of molten iron dropping through the slag at 1773 K. The desulfurization reaction mechanism of high alumina blast furnace slag is explained from the aspects of slag structure and component activity, which provides a theoretical basis for the reasonable selection of a slag making system under the condition of a high alumina content. The effects of different B and w(MgO)/w(Al2O3) on the slag structure 2343 analyzed by Fourier transform infrared spectroscopy (FT-IR). The results show that when w(MgO)/w(Al2O3) = 0.50 and w(Al2O3) = 20%, the desulfurization ability and MgO activity of slag increased with the increase of B; when w(Al2O3) = 20% and B = 1.30, the desulfurization ability and MgO activity of the slag increased with the increase of w(MgO)/w(Al2O3). The FT-IR analysis showed that with the increase of B or w(MgO)/w(Al2O3), the dissociated free oxygen ions (O2−) in the slag increased, and the dissociated free oxygen ions (O2−) interacted with the bridging oxygen (O0) of silicate, which made the complex Si-O structure in the slag gradually depolymerize and increase the desulfurization ability.