Tailoring of Solidification and Crystallization Behaviour 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 (BF) slag, its solidification and crystallisation behaviour are studied using the JMAK model and experimental techniques. The maximum rate of crystallisation occurs at a higher heating rate (20⁰C /min). Mould materials (copper, iron, graphite and sand mould) with different thermal conductivity are used to control the cooling rate of molten slag. XRD shows that, in the slowest cooled sample, gehlenite, akermanite and calcium aluminium magnesium silicate (CaMg2Al16O27) is formed as a crystalline phase (80 %) while the fasting cooling sample produces a 98 % glassy phase. SEM studies show that the growth and morphology of mineral phases are a function of cooling rate. Glass-ceramics with 50 % crystalline and 50 % glass phase can be produced by direct cooling in the mould materials, which has a thermal conductivity of 20-30 W/mK with a cooling rate of 120-150 K/min.