Prof. Dr. Rafael Salomão da UFSCar e Conselheiro da ABC
Artigo: “Hydrotalcite (Mg6Al2(OH)16(CO3)•4H2O): A Potentially Useful Raw
Material for Refractories”
Revista INTERCERAM – REFRACTORIES MANUAL I/2013
Pages 187 a 191
Hydrotalcite also known as aluminum-magnesium layered double hydroxide, was broadly investigated in the past decade due to its many applications in catalysis, adsorptive flotation and flame retardant in polymers. In refractory castables, hydrotalcite was observed to be a by-product of the hydroxylation reaction between magnesia sinter and hydratable alumina or calcium aluminate cement. It can be synthesized using coprecipitation reactions from Al-Mg soluble salts. Novel methodologies were recently developed to produce large quantities of hydro talcite starting from caustic magnesia and aluminum hydroxide under controlled temperature. Considering its chemical composition (Mg6Al2(OH)16(CO3)•4H2O), which is roughly 60 mass-% MgO and 40 mass-% Al2O3, and the many advances made in its synthesis, hydrotalcite has great potential for use in refractories, especially those involving in situ generation of spinel (MgAl2O4). This paper critically reviews the occurrence of hydrotalcite in refractories, the most effective synthesis methods, and presents some potential uses in refractory applications.
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