Reaction Characteristics of Magnesia–Spinel Refractories with Cement Clinker

Abstract

The adherence ability of cement clinker on magnesia–spinel refractories is investigated, using a sandwich test, at 1550°C for 30 min under a load of 5.3 kPa. Fractional factorial experiments determine that the silica ratio (SR)—SiO2/(Al2O3+Fe2O3) and particle size of raw meal, as well as heating rate, have a significant effect on adherence ability. Microstructural analyses indicate that the adherence ability depends upon reactions between clinker and refractories at high temperature. Only spinel reacts with CaO and 3CaO·SiO2 from clinker to form n‐calcium aluminate (such as 3CaO·Al2O3, 12CaO·7Al2O3, CaO·Al2O3), but there is no reaction between MgO and the clinker. Fine crystalline spinel, evenly distributed in magnesia‐based brick, is prone to reacting with lime‐containing phases from clinker to form low melting phases and a belite‐enriched zone at the clinker/brick interface. This reaction positively contributes to the high adherence on a magnesia−spinel brick. The high content of liquid in clinker with low SR accelerates reactions between spinel and clinker, while a limited reaction occurs at the brick/clinker interface with high silica.