A post‐mortem analysis of the used gel‐bonded Al₂O₃–MgAl₂O₄ castables in an industrial steelmaking ladle

Abstract

In this work, a cement-free alumina-spinel (Al 2 O 3 -MgAl 2 O 4 ) castables with a new aluminum-magnesium gel binder were developed to line the Ruhrstahl Heraeus refining ladle, chemical attacks, and degradation mechanisms of the used alumina-spinel castables after industrial trials were investigated. The results indicated that a reaction product layer of (Mg, Fe)Al 2 O 4 was observed between the slag layer and penetration layer (PL), which was mainly derived from the reaction between MgAl 2 O 4 spinel in the refractory matrix and FeO t from slag or an oxidation of steel, and thereby prevented the further penetration of FeO t . Meanwhile, the in situ spinel could also entrap slight CaO, SiO 2 , and FeO t from the infiltrated slag to form composite spinel in the PL. Moreover, chemical corrosion/penetration and structural spalling dominated the degradation process of the refractory lining in this case. Cracks formed between the deteriorated layer and original layer because of mechanical and thermal stress, which caused spalling from the refractory's hot face.

Particle grading effect on properties of reactive MgO‐bonded castables

“…Refractory castables encompass a broad range of materials that have undergone significant advancements, [1][2][3][4] leading to intricate and technically advanced formulations aimed at fulfilling highly demanding and rigorous industrial applications at elevated temperatures. [5][6][7][8][9][10] The primary features of castables consist of a well-chosen combination of raw materials, including aggregates, fillers, binders, and admixtures, [11][12][13][14][15][16][17][18] which leads to a deliberately designed particle gradation affecting the flowability and density of the mixture, [19][20][21][22][23][24][25] alongside the binder that influences both the green mechanical strength and the high-temperature properties, including phase evolutions. 6,[26][27][28] More recently, reactive MgO (RM) is considered as hydraulic binder to prepare castables with superior properties and performance.…”