Effect of basicity on physical properties of ladle slags of CaO ‒ SiO₂ ‒ Ce₂O₃ ‒ Al₂O₃ ‒ MgO system

Abstract

The authors studied the physical properties of the slags of CaO ‒ SiO2 ‒ Al2O3 ‒ MgO system containing cerium oxide. The developed slags are based on a calcium silicate system, the basicity (CaO)/(SiO2) of which has a great influence on the slag properties. Generalization of the performed studies results allowed obtaining new data on the effect of basicity in cerium-containing slags of the studied oxide system on viscosity, temperature of crystallization onset and structure. Experimental studies of the physical properties of cerium-containing slags showed that with an increase in basicity of 2.0 ‒ 5.0, an increase in temperature of crystallization onset and viscosity is observed associated with structure of the formed slags. An increase in basicity from 2.0 to 5.0 contributes to an increase in viscosity from 0.20 to 0.41 Pa·s at 1500 °C and an increase in the crystallization temperature from 1397 to 1497 °C. The structural analysis showed that the structure of the cerium-containing slag is influenced by both the Si4+ ion and the Al3+ ion, which are grid-forming agents. Silicon ions in this system are present in the form of [SiO4 ]-tetrahedra, whereas aluminum ions are present in form of [AlO4]-tetrahedra and [AlO6]-octahedra. With an increase in basicity 2.0 to 2.5, the silicon structure becomes more complicated, and then at a basicity of 3.5 ‒ 5.0 it becomes simpler, whereas the aluminate one becomes more complicated due to an increase in the content of CaO, which participates in charge compensation of polymerized structural units [AlO4 ]-tetrahedra with the formation of a more stable tetrahedral structure, and as a result of increased slag viscosity. Slags of the studied oxide system containing 15 % Ce2O3 are characterized by a sufficiently high liquid mobility in the considered basicity range.