MgO fumes as a potential binder for in situ spinel containing refractory castables

Binder effect on ZnAl2O4-containing high-alumina refractory castables

“…Such a complex structure results in interesting features, as the spinel phase can trap Mn 2+ , Fe 2+ and Fe 3+ ions in its structure via solid solutions. Consequently, spinel-containing refractories usually present enhanced corrosion resistance as the withdrawal of these ions from the slag may result in a silica-rich viscous liquid, which will not easily infiltrate into the ceramic lining porosity [12][13][14].…”

Alumina‐spinel castable for steel ladles: An overview

“…This reaction is accompanied by a volume expansion that causes a reduction in porosity and helps to reduce slag penetration. 23 For in situ-based alumina-spinel castable, the use of magnesia fumes was reported 42 to show better properties, like densification, improved hot strength, and higher resistance against thermal shock and corrosion compared to that of dead burnt magnesia. The size of magnesia grain also influences spinel formation; reducing the size was reported to produce a higher overall expansion.…”

“…40 Magnesia addition in high alumina refractory castable helps in controlling hydration rate, induces binding effect with the castable components, enhances green mechanical strength, and after heating above 1000 • C, spinel forms accompanied with a volumetric expansion. 42,43 Ideally, spinel contains magnesia and alumina in equimolar ratio, and stoichiometric spinel contains 28.2-wt.% MgO and 71.8-wt.% Al 2 O 3 . However, as the temperature rises, a wide range of non-stoichiometry exists in the system.…”

Crack-free caustic magnesia-bonded refractory castables

“…Calcium aluminate cements (CACs) are still the main binder for different refractory systems [5][6][7], but many studies have investigated the advantages and drawbacks associated with the use of hydratable alumina [8,9], colloidal suspensions [10][11][12], chemical additives [13][14][15] and even magnesium oxide [16][17][18][19][20], as alternative options for this purpose. The latter has the ability to react with water (in a liquid state or as vapor) giving rise to crystals of the brucite phase [Mg(OH)2], which may fill in the pores available in the consolidated structure of the refractories, inducing the hardening of the molded pieces.…”