Effect of Basicity on Metallurgical Properties of Fluxed Pellets with High MgO Content

Abstract

The basicity (CaO/SiO₂) has an important influence on the metallurgical properties of fluxed pellet with high MgO content. This paper studied the effect and function of basicity on metallurgical properties of fluxed pellet, such as compressive strength, reduction disintegration, reduction swelling and the softening-melting behaviour systematically with simulating BF conditions. From the results, with increasing basicity from 0.6 to 1.3, the compressive strength increases from 2842 N to 3532 N, the pore structure become more compact, and the following phase transformation is observed from Fe₂SiO₄ → Ca₂SiO₄, Mg_XFe_2−XSiO₄ → MgFe₂O_4. Additionally, the reduction properties of high magnesium fluxed pellets are improved, the low temperature disintegration index increases from 89.8% to 97.78%, and the reduction swelling index decreases from 19.02% to 8.45%. With the increase of basicity in the pellets, the softening interval and melting interval of the pellets decrease slightly, and the position of the cohesive zone shift down and gradually become thinner, which improve the permeability of the cohesive zone. In the basicity range of 0.6–1.3, the optimum metallurgical properties of pellets are observed for the basicity of 1.1.