Study on the fluidity and structure of blast furnace slag controlled by TiO 2 and Al 2 O 3 coupling

Abstract

Both Al₂O₃ and TiO₂ significantly influence the properties and structure of BF slag, particularly when the Al₂O₃ content exceeds 16 mass%. In this article, the effects of TiO₂ (0–20 mass%) on the viscosity of SiO₂-CaO-MgO-(16–20 mass%) Al₂O₃-TiO₂ BF slag system were measured by rotating cylinder method when the R₂ was 1.25. The results show that the viscosity increases with the increase of Al₂O₃ content in slag, and the degree of polymerisation of slag also increases. The viscosity decreases first and then increases with the increase of TiO₂ content in slag. The inflection point of slag viscosity occurs when the amount of TiO₂ added is more than 8 mass %. The results of mineral phases show that under the condition of nitrogen partial pressure and reduction, with the increase of TiO₂ content in the slag. The structure of the slag was studied by Raman spectroscopy. The results show that TiO₂ added in the BF slag acts as a network modifier, which can depolymerise the aluminate and silicate network structures. The complex Q³ structure is depolymerised into simple structures Q⁰ and Q¹, which reduces the degree of polymerisation of the slag system. However, when the addition of TiO₂ is more than 8 mass %, the formation of high melting point TiN, TiC and TiC/N in the slag leads to the increase of slag viscosity. It can be seen that the fluidity of high alumina BF slag (≥16 mass %) can be controlled by adding a certain amount of TiO₂.