High‐Temperature Thermophysical Property Characterization of Molten Blast Furnace Slag: A Critical Reviews

Centrifugal granulation‐assisted thermal energy recovery (CGATER) remains the leading technology for the iron and steel industry to enable the low‐carbon treatment of high‐temperature blast furnace (BF) slag. Accurate knowledge of the thermophysical properties of BF slag is pivotal for the commercialization of the CGATER. However, it presents a formidable task to obtain these quantities due to the extremely high temperature of molten BF slag (≈1500 °C). To date, the thermophysical properties of BF slag have not been well characterized yet. Herein, five typical thermophysical properties including density, viscosity, surface tension, thermal conductivity, and emissivity are scrutinized with emphasis on the experimental measurements and empirical estimates. The working principles of these measurement methods are briefly overviewed and their merits and demerits are highlighted. It is noted that density, viscosity, and surface tension have been intensively studied; the quantities can be estimated with moderate uncertainty. However, the thermal conductivity and emissivity of BF slag are less tackled, mainly because of the scarcity of measurement tools at high temperatures. In the future, innovative measurement tools tailored for high‐temperature materials are essential, not only for enriching the thermophysical property database of BF slag but also for paving the way toward characterizing other complex high‐temperature melts.