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

• Main Authors: Yongchun Guo, Fengman Shen, Haiyan Zheng, Shuo Wang, Xin Jiang, Qiangjian Gao
• Format: Article
• Language: English
• Published: MDPI AG 2021-08-01
• Series: Crystals
• Subjects: slag; <i>B</i>(<i>w</i>(CaO)/<i>w</i>(SiO₂)); <i>w</i>(MgO)/<i>w</i>(Al₂O₃); desulfurization ability; sulfur distribution ratio(<i>L</i>s); FT-IR
• Online Access: https://www.mdpi.com/2073-4352/11/8/910

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 <i>B</i>(<i>w</i>(CaO)/<i>w</i>(SiO₂)) and <i>w</i>(MgO)/<i>w</i>(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 <i>B</i> and <i>w</i>(MgO)/<i>w</i>(Al₂O₃) on the slag structure 2343 analyzed by Fourier transform infrared spectroscopy (FT-IR). The results show that when <i>w</i>(MgO)/<i>w</i>(Al₂O₃) = 0.50 and <i>w</i>(Al₂O₃) = 20%, the desulfurization ability and MgO activity of slag increased with the increase of <i>B</i>; when <i>w</i>(Al₂O₃) = 20% and <i>B</i> = 1.30, the desulfurization ability and MgO activity of the slag increased with the increase of <i>w</i>(MgO)/<i>w</i>(Al₂O₃). The FT-IR analysis showed that with the increase of <i>B</i> or <i>w</i>(MgO)/<i>w</i>(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.