Existence Forms of Magnesium Oxide in Steel Slag by Chemical Phase Separation

Abstract

Magnesium oxide solid dissolved in silicate phase, mesophase and RO-phase which are the major constituents of steel slag. The MgO exists in the steel slag with complex forms, which results in the bad soundness of the steel slag. In this paper, the silicate phase and mesophase were separated by salicylic acid methanol solution and potassium hydroxide-sucrose solution respectively and were studied combining with the XRD and SEM. The results show that the silicate phase and mesophase can be fully dissolved, however, the RO phase is not influenced by the two solutions in this process. The content of magnesium oxide existed in different minerals can be detected by chemical analysis. It can be found that the magnesium oxide mainly exists as RO-phase in steel slag, and some of them exist as free state, while only a small quantity of solid dissolve in the silicate phase and mesophase.

Effect of temperature on the present forms of MgO in the reconstruction of steel slags

“…Because there is almost no FeO in electric furnace slag, MgO exists purely as periclase [3].The hydration of pure periclase produces Mg(OH) 2 , which affects the structure of steel slag. However, the effect of RO phase on the structure of steel slag remains uncertain [4][5][6][7].…”

Study on Extraction of Mesophase from Steel Slag by Potassium Hydroxide-Sucrose (KOSH) Solution Method

“…It was consistent with the results of chemical analysis, so KOSH solution can be dissolve the mesophase, and had no significantly effect on silicate phase and RO phase. (5) Mechanism of extraction In multiphase system consisted of solid and liquid, the reaction was occurred in the solid-liquid interface, also known as surface reactions, the surface chemical reactions of mineral dissolved may include three steps, their were adsorption, catalytic reactions and mineral dissolution [5]. Some scholars had pointed out that, the organic ligand by polar organic and metal ions can reduce the activation energy of mineral hydrolysis.…”