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 15501C for 30 min under a load of 5.3 kPa. Fractional factorial experiments determine that the silica ratio (SR)-SiO 2 /(Al 2 O 3 1-Fe 2 O 3 ) 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 Á SiO 2 from clinker to form n-calcium aluminate (such as 3CaO Á Al 2 O 3 , 12CaO Á 7Al 2 O 3 , CaO Á Al 2 O 3 ), but there is no reaction between MgO and the clinker. Fine crystalline spinel, evenly distributed in magnesiabased 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 magnesiaÀspinel 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.

Chemical corrosion mechanisms of magnesia–chromite and chrome-free refractory bricks by copper metal and anode slag

“…Type B is typically used for lining cement rotary kilns but can also be used in the steel industry. 11,12 Type C was developed specifically for application in the burning section of precalciner kilns. 13 Type D is mostly applied in the furnaces used in cement and lime production, whereas the main application area of type E is the high-wear lining of steel ladles.…”

Qualitative and quantitative investigation of post–mortem cement refractory: The case of magnesia–spinel bricks

“…Furthermore, the MgO dissolved form with CaO-SiO 2 -Al 2 O 3 -Fe 2 O 3 an eutectic less than 1350 ° C [4], which promoted the reactions illustrated by equations (IV), (IIV) and (IIIV) [28]. …”

“…The mayenite could be generated also from the free lime according to the reaction (II) [4]. The XRD of crusting (Fig.3), which surmounts the hot side of the bricks, revealed the presence of the uncombined lime.…”

“…Indeed, the dissolution of alite and spinel lead to the mayenite formation between 1000°C and 1350°C [24], probably, following the reaction (I) [4].…”

“…In view of that, magnesia -spinel MgO -MgAl 2 O 4 bricks are now frequently used to protect the burning zone because of their high thermal and chemical resistance. In fact, in this zone, the refractory lining is exposed to the thermo-chemical stresses resulting from a variety of corrosive agents: The change in the flame temperature, the material and gases, the amount and viscosity of the liquid phase, the contents of FeO, Fe 2 O 3 , Fe 3 O 4 , SiO 2 , the contents of alkalis and sulfur [1][2][3][4][5][6][7][8]. The kiln alignment, as well as his ovality, represents the mechanical stresses.…”