Thermophysical Properties of the Desulphurization Slags With Various CaS and CaO/Al ₂ O ₃ Ratio

Low sulphur content is essential for high‐quality steels and can be achieved using desulphurization slag. During the desulphurization process the chemical composition of the slag changes leading to alteration in its thermophysical properties, such as surface tension, viscosity, and density. However, the influence of CaS on these thermophysical properties is poorly investigated. In this study, the influence of various CaS content (0–10 wt%) and CaO/Al 2 O 3 ratio (1.87–1.36) on the viscosity, surface tension, and density of desulphurization slags is investigated. Measurements of surface tension and density are carried out using the maximum bubble pressure method, while viscosity is determined using the rotating bob method. The obtained results show that a decrease in viscosity value is observed with an increase in CaS content only up to 6 wt%; however, further addition of CaS sharply increases viscosity. In case of surface tension and density measurements, an increase in CaS content up to 10 wt% results in a reduction of both property values. Additionally, to study microstructure differences of the investigated slags, they were quenched and examined using scanning electron microscopy (SEM) and Energy‐dispersive X‐ray spectroscopy (EDX).