Application of Calcia Electric Arc Furnace Hearth and Its Effect on Oxide Inclusions in Steel

Abstract

In order to decrease the macroscopic inclusions containing spinel (MgO·Al₂O₃), the main mineral phase of oxide inclusions in steel, calcia refractories were newly developed for electric are furnace hearth materials. Some properties of calcia hearth materials and the effects of using calcia hearth materials on oxide inclusions were studied.
Main results are summarized as follows.
By using calcia hearth materials, not only the quantity of MgO in the form of oxide inclusions, but also the quantities of Al₂O₃ and SiO₂ were lower than those in the case of using magnesia or dolomite hearth materials. The quantity of CaO in the form of oxide inclusions did not increase. Accordingly, the total quantity of oxide inclusions decreased to less than the half for the case of using magnesia or dolomite hearth materials.
Moreover, it was recognized that the sulfide inclusions decreased remarkably. By these results, it was confirmed that number of macroscopic inclusions in steel were decreased and cleanness of steel was improved remarkably by using calcia hearth materials.