Weak magnetic effect and free radical reaction mechanism on the dissolution of lightweight magnesia in CaO–Al2O3–SiO2 melts

Abstract

Lightweight magnesia-based refractories play a crucial role in achieving energy savings and carbon reduction in steelmaking furnaces. The primary requirement is to make lightweight magnesia refractories with high corrosion resistance. The introduction of a weak static magnetic field is also a promising way to improve the slag resistance of lightweight refractories in addition to optimizing the composition and structure of the refractories. In this paper, the dissolution behavior of the lightweight magnesia in CaO–Al2O3–SiO2 molten slags at and above 1600 °C under weak static magnetic field is presented. The influence of the weak static magnetic field on the dissolution rate was analyzed, the behavior from the perspective of free radical and kinetics was discussed, and the influence of different calcia–silica weight ratios (C/S) on slag, magnetic flux density and the reaction mechanism are revealed. The results show that the dissolution rate of the lightweight magnesia in the molten slag presents a significantly weak magnetic effect, with a reaction inhibition interval of 2–4 mT in the range of 0–16 mT magnetic field intensity, and the key inhibition threshold surpasses that of alumina. The mechanism of the free radical formation and reaction during magnesia dissolution in high-temperature slag is explained and illustrated. The relationship between the magnetic flux density, superoxide radical content, and dissolution rate is presented, providing theoretical guidance for developing magnetic combined magnesia refractories.