Original Article

Determination of density and surface tension of CaO-SiO₂-Fe_xO molten slag by pendant drop method

¹ State Key Laboratory of Advanced Refractories, Wuhan University of Science and Technology, Wuhan 430081, PR China
² Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081, PR China

^* Corresponding author: gaoyunming@wust.edu.cn; liguangqiang@wust.edu.cn

Received: 17 December 2024
Accepted: 12 March 2025

Abstract

In order to promote application of pendant drop method in high-temperature determination, density and surface tension values of CaO −SiO₂–20wt% ΣFeO molten slag with different masses (volumes) were measured in heating and cooling modes using a novel ring-shaped pendant drop forming device with known size. The effects of the measurement mode, residual bubbles in the droplet, and droplet mass were also analysed. The results indicate that the discrepancies of the obtained properties in the two modes are mainly due to variation in the slag composition and the influence of bubbles in the droplet. The residual bubbles result in a decrease in the density, which in turn reduces the surface tension. The slag mass (volume) affects the curvature radius and shape factor of the droplet, and then the measured density and surface tension. The average values of the three measurements with close to the critical slag mass of the pendant drop forming device in the cooling mode indicate that the determined density and surface tension values increase as the temperature decreases from 1650–1450 °C, and the absolute errors for density are within the range of ±0.045 g / cm³ at different temperatures, while those for surface tension are within ±4.2 mN / m. The use of droplet with close to the critical mass can reduce the measurement errors. Additionally, the relationship between the size of the pendant drop forming device and the approximate critical mass of powder slag compact is established, thereby enhancing the efficiency and reliability of the measurement process.