Effect of Fluorspar and Industrial Wastes (Red Mud and Ferromanganese Slag) on Desulfurization Efficiency of Molten Stee
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LUORSPAR is well known as one of the most widely used materials for controlling the viscosity and melting point of slag in the steelmaking process. In general, the lower viscosity of the slag, the more positively it affects sulfur refining, which is one of the main tasks of ladle treatment.[1] Putan et al.[2] reported that increasing the slag viscosity from 0.15 to 0.45 Pa s (1.5 to 4.5 poise) leads to a 30 pct reduction in the steel–slag interaction surface. Since the viscosity of the slag is important in metal–slag reactions, many researchers have investigated the effects of CaF2 on the viscosity of slag.[3–10] Many researchers found that the viscosity of slag decreases with the addition of CaF2.[3–6] Kozakevitch[7] explained a decrease in viscosity of slags containing fluorspar in terms of the breakdown of the silicate
TAE SU JEONG is with the Department of Materials Engineering, Hanyang University, Ansan 15588, Korea. JOO HYUN PARK is with the Department of Materials Engineering, Hanyang University, Ansan 15588, Korea, and also with the Department of Materials Science and Engineering, KTH Royal Institute of Technology, Stockholm 100 44, Sweden. Contact e-mail: [email protected] Manuscript submitted February 16, 2020.
METALLURGICAL AND MATERIALS TRANSACTIONS B
network by fluoride ions. Maclean et al.[8] explained that the addition of fluorspar to the silicate melt interferes with the polymeric constitution of the melt and increases the melt’s fluidity as the degree of depolymerization increases. Park et al.[9] concluded that the effect of CaF2 on the viscous flow of slag can be understood from a decrease in polymerization degree by F ion, and the effect of CaF2 on the viscosity was significant in the highly basic (solid + liquid coexisting) system. Kim and Park[10] observed that the viscosity of low-silica calcium aluminosilicate melts at fixed MgO (5 mass pct) and CaF2 (10 mass pct) decreases with increasing CaO/ Al2O3 and CaO/SiO2 ratios and that the addition of a small amount (5 mass pct) of CaF2 reduces the viscosity of the slag because it liberates the [SiO4]4 unit from the aluminate network. However, the effect is insignificant when more than 10 pct CaF2 is added. However, decreasing the viscosity of the slag by adding CaF2 can affect the refractory degradation.[11–13] Han et al.[11] investigated slag penetration and refractory degradation according to changes in the CaF2 content in the ladle slag using a resistance furnace and an induction furnace. As the CaF2 content increased, the depth of penetration of slag into the refractory material increased and the detachment of MgO grains were observed. It was concluded that the addition of CaF2 decreases the viscosity of the slag, which leads to more aggressive erosion of the refractory. Additionally, the
penetrated slag containing CaF2 decreases the melting point of the refractory binder and detach MgO grains, increasing damage to the refractory. Park et al.[12,13] found that when CaF2 is added to the calcium silicate slag, the slag fluidity increases, and the corro
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