Degradation Behavior of MgO Refractory by BOF Slags Containing Calcium Chloride

• Published in: Metallurgical and materials transactions. B, Process metallurgy and materials processing science Process metallurgy and materials processing science, 2022-10, Vol.53 (5), p.3115-3123
• Main Authors: Yan, Ziwen, Deng, Zhiyin, Zhu, Miaoyong
• Format: Article
• Language: English
• Subjects: Calcium chloride; Calcium fluoride; Characterization and Evaluation of Materials; Chemistry and Materials Science; Degradation; Diffusion barriers; Diffusion layers; Magnesium oxide; Materials Science; Metallic Materials; Nanotechnology; Original Research Article; Slag; Solid solutions; Steel making; Structural Materials; Surfaces and Interfaces; Thin Films
• ISSN: 1073-5615; 1543-1916
• DOI: 10.1007/s11663-022-02590-7

In order to clarify the degradation behavior of MgO refractory by BOF slags containing CaCl 2 , some laboratory experiments were carried out at steelmaking temperature to simulate the interaction between the refractory and slags. Three slag systems ( viz. CaCl 2 -free, CaCl 2 -added and CaF 2 -added slags) were considered in this study. It is found that a solid solution magnesiowustite (MW) layer can be observed at the boundary between the refractory and the slags, and its thickness increases with time. In the MW layer, MgO diffuses to the slag, while FeO diffuses oppositely to the refractory. The dissolution of MgO refractory into the CaCl 2 -added slags reduces the solubility of CaCl 2 in the slags, and causes a CaCl 2 layer precipitated near the MW layer. The CaCl 2 layer acts as a barrier to hinder the diffusion of MgO and FeO, thus leading to a thinner MW layer and a lower MgO content in the slags in contrast to the CaCl 2 -free slag. In the case of the CaF 2 -added slag, the thickest MW layer and the highest MgO content are obtained. So, the addition of CaCl 2 into BOF slag would weaken the degradation of MgO refractory, while the addition of CaF 2 plays an opposite role.