As a commonly used sintering equipment in the ceramics industry, roller kilns play an important role in the production process of ceramic products. However, in the roller kilns of many ceramic factories, the refractory bricks on the kiln roof and side walls in the front section of the firing area often have varying degrees of bulging, delamination and peeling, especially at the top of the kiln. The corrosion of refractory fire bricks not only affects the life of the kiln bricks, but also seriously affects the quality of the ceramic tiles if the layered brick slag on the top of the kiln falls off. What are the causes of corrosion of refractory firebricks in roller kilns? How to make technical improvements?
Test samples were selected from two kilns with refractory brick corrosion in different ceramic factories, and the X-ray fluorescence spectrochemical analysis method was used to conduct physical phase analysis on the original bricks and peeling fragments of the two refractory bricks, and the corrosion process of the refractory fire bricks was found. Compounds containing potassium, sodium and zinc elements are formed: zinc-aluminum spinel, leucite, sodalite, potassium orthoclase, feldspar and other compounds.
The corrosion of refractories bricks lining ceramic roller kilns is mainly caused by the erosion of alkali metal compound vapor and zinc compound vapor in the kiln gas. These corrosive gases are deposited in the pores and joints of the refractory bricks, and chemically react with alumina, silica and other components in the refractory brick body to form new compounds. Most of the mullite crystals in the brick body are decomposed, resulting in brick Changes in body chemical composition and structure. Because the expansion coefficient of the eroded layer of refractory fire bricks is very different from that of the original refractory firebricks, the bricks will bulge, delaminate and peel off.
In order to solve the corrosion problem of refractory bricks lining the ceramic roller kiln, the following technical improvement measures are proposed:
(1) Increase the density of refractory fire bricks. High-density refractorybricks have smaller porosity, which can reduce the permeability of flue gas, thereby reducing the erosion of corrosive components on the bricks and improving the corrosion resistance of the bricks.
(2) Use refractory bricks with high alumina content. For example, high alumina bricks, corundum bricks, alumina hollow ball bricks, etc. have high alumina content and good alkali resistance, and can effectively resist the corrosion of alkali metal gases.
(3) Use alkali-resistant bricks. Alkali-resistant bricks have excellent alkali erosion resistance and can react with alkali compounds in the kiln gas at a certain temperature, and quickly form a closed and dense protective glaze layer on the brick surface. This protective glaze layer can prevent the continued infiltration of alkali, avoid "alkali cracking" damage to the brick body, and improve the corrosion resistance of the fire bricks.
(4) Spray alkali-resistant refractory paint on the surface of the refractory bricks. Alkali-resistant refractory coatings can resist the erosion of alkali metal vapor. By spraying alkali-resistant refractory coatings on the surface of fire bricks, a protective layer can be formed on the surface of the refractory fire bricks, which can reduce the porosity of the brick surface and reduce the impact of corrosive components on the bricks. Corrosion, very suitable for kilns where fire bricks have corroded. During construction, the corrosion layer needs to be polished off before spraying. This measure can reduce the time and cost of kiln shutdown maintenance and extend the service life of refractory bricks.
