Tailoring of Solidification and Crystallization Behavior of Blast Furnace Slag for Developing Glass–Ceramics During Melt Cooling

Abstract

In an attempt to develop glass ceramics during the direct cooling of molten blast furnace slag, its solidification and crystallization behavior are studied using the JMAK model and experimental techniques. The maximum rate of crystallization occurs at a higher heating rate (20 ℃/min). Mold materials (copper, iron, graphite, and sand) with different thermal conductivities are used to control the cooling rate of molten slag. XRD analysis shows that, in the slowest cooled sample, gehlenite, akermanite, and calcium aluminum magnesium silicate are formed as a crystalline phase (80%), while the fasting cooling sample produces a 98% glassy phase. SEM studies display that the growth and morphology of mineral phases are a function of the cooling rate. Glass ceramics with 50% crystalline and 50% glass phases can be produced by direct cooling in the mold materials, which has a thermal conductivity of 20–30 W/mK at a cooling rate of 120–150 K/min. © The Minerals, Metals & Materials Society 2025.