| In this paper, the wear mechanism of direct-bonded magnesia-chrome bricks and magnesia-spinel bricks used in the burning zone and the transition zone respectively for the large scale dry-process cement rotary kiln of Huaxin Cement Co.Ltd. was analyzed. The properties and the microstructure as well as the slag resistance of these environment-friendly refractories were inveatigated in order to substitute the imported products and improve the lining life.The main corrosion mechanism of cement clinker on the low-chrome magnesia-chrome brick and the magnesia-spinel bricks is the formation of low smelting compounds caused by the reaction between cement clinker and components in the brick. The infiltration and deposition of alkali salts in the form of vapor or liquid will gradually result in a complete filling of the apparent pore and brick densification.Besides the filling of apparent pore, the main corrosion mechanism of alkali salts on the low chrome magnesia-chrome brick is the formation of K2CrO4 and sulphates which is formed through the reaction of alkali salts and magnesia /chrome. And then they migrate to the cold face together with other salts, which results in the structure brittle of the hot face.The research on the bricks after being used in the large scale dry-process cement rotary kiln showed that the main wear mechanism could be the co-action of thermal shock and chemical corrosion caused by the attack of clinker and temperature fluctuation. Therefore, the improvement of toughness and spalling resistance is the main measure to improve the lining life.These results showed that: the direct bonded structure would be destroried by the formation of low smelting compounds caused by the reaction between cement clinker and components in the brick. With the action of abrasivion and thermal shock, the hot facewould spall. And this will be the reason for worse coating adherence of magnesia-alumina spinel bricks.
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