Observation of the crystallization behavior of a slag containing 46 wt pct CaO, 46 wt pct SiO2, 6 wt pct Al2O3, and 2 wt pct Na2O using the double hot thermocouple technique

In this work, isothermal crystallization of a synthetic slag containing 46 wt pct CaO, 46 wt pct SiO2, 6 wt pct Al2O3, and 2 wt pct Na2O has been investigated by means of double hot thermocouple technique (DHTT). The effect of Na2O content on crystallization time was confirmed. Two different types of calcium silicate crystals were observed. Calcium di-silicate forms at temperatures above 1150 degrees C and calcium tri-silicate precipitate at temperatures below 1050 degrees C. A mixture of the two types of calcium silicate has been observed between the two temperatures. The tendency of crystals to become richer in calcium at low temperatures that has also been observed in previous published works has been confirmed. No effect of the cooling rate on crystallization start time was confirmed in the range of cooling rates applied in this investigation.