Effect of Basicity, Al₂O₃ and MgO content on the softening and melting properties of the CaO-MgO-SiO₂-Al₂O₃ high alumina quaternary slag system

Department of Metallurgical and Materials Engineering Rourkela, National Institute of Technology, 769008 Rourkela, India
e-mail: yedlan@nitrkl.ac.in

Received: 26 November 2015
Accepted: 4 March 2016

Abstract

The flow characteristic temperatures of the selected quaternary CaO-MgO-SiO₂-Al₂O₃ slags have been experimentally measured by performing softening and melting tests using a high temperature microscope in accordance with German standard 51730. An effective statistical model is developed through constructing empirical equations by regression analysis method to predict Softening temperature (ST), Hemispherical temperature (HT), and Flow temperature (FT) based on Al₂O₃ (25%–30%) content, CaO/SiO₂ (C/S ratio: 0.9–1.4), and MgO (4%–12%) content. The effect of basicity, MgO and Al₂O₃ content on characteristic temperature are also studied. FactSage 6.4 data base is used to calculate liquidus temperature of the above quaternary slags and compared with the experimental and regression results. The experimental results show that, increase in Al₂O₃ content increases ST and HT while decreases FT of the slags. The ST, HT and FT increase with increase in C/S ratio. Increase in MgO content decreases both ST and HT while increases FT of the slags. The liquidus temperature obtained from FactSage 6.4 are found to correspond well with the experimental and regression data. Under the range of composition examined, a high Al₂O₃ (30%) and high C/S ratio (1.4) coupled with low MgO (4%) content is beneficial for the blast furnaces running with high Alumina slags, as it ensures the formation of a short slag.