1. Types of damage
The impact of production operations on refractory materials in kilns can be roughly divided into the following four types, but the actual impact is often caused by the simultaneous existence of several reasons.
1.1 Peeling off
(1) Thermal spalling: Rapid thermal changes such as spalling or adhesion and detachment of crusts during the early stages of ignition can cause internal thermal stress in the bricks, resulting in cracking of refractory bricks, which is called thermal spalling.
(2) Mechanical spalling: The phenomenon of refractory brick cracking caused by mechanical stresses such as the influence of large kilns, melting of joint iron plates, or the load on bricks is called mechanical spalling.
1.2 Melting damage
The high heat load during the initial ignition or adhesion and detachment of the crust, as well as the liquid phase composition of the cement raw material, will form low melting point substances, causing melting damage to the refractory material. Magnesia chromium bricks or chromium free bricks in the firing area are usually prone to melting damage, but improper production operations can also cause melting damage to spinel bricks in the cooling area or adhesion and detachment area of the crust, and even clay bricks in the firing area.
1.3 Wear and tear
The loss caused by cement raw materials on the surface of bricks. It is divided into mechanical wear generated in the calcination area and the area where the crust adheres and falls off, as well as high-temperature wear generated in the firing area or cooling area, including melting damage caused by cement liquid phase components. When using high alumina clay bricks in the calcination area, they may react with cement raw materials at lower temperatures than alkaline bricks, producing low melting point products. Therefore, sometimes they may also cause wear on the side near the high heat load crust adhesion and detachment zone.
1.4 Organizational embrittlement
Brittle phenomenon caused by the structural damage of bricks due to thermal stress, mechanical stress, and erosion of foreign components. Thermal stress is often generated in the areas of adhesion and detachment of the crust, as well as in the burning area, due to frequent temperature changes caused by the adhesion and detachment of the crust; Mechanical stress is caused by the adhesion and detachment of large kilns or crusts, as well as the load on bricks.
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