4. Damage of nepheline
Since the density of nepheline is smaller than that of the brick, when the nepheline crystals precipitate, it is accompanied by a larger volume expansion, making the brick structure loose. Although the melting of part of the crystalline phase in the brick at this time will increase the viscosity of the glass liquid and have a certain bonding and protective effect on the loose structure, it still cannot completely block the air flow, material and glass liquid erosion in the kiln, and the effects of gravity, resulting in cracking, Peel off into the glass liquid and form glass stones. The peeled wound surface continues to be eroded and washed away by the glass liquid and continues to peel off. The result will inevitably lead to erosion and disintegration of the fused zirconium corundum bricks.
Extend the service life of fused zirconium corundum bricks in glass electric furnaces
As we all know, the glass tank kiln melts horizontally, the material liquid level moves horizontally, and the three-phase interface is seriously eroded except for the liquid flow hole. Electric glass melting furnaces melt vertically, and most of them use cold top melting. The glass liquid surface is covered by a layer of raw material, and there are fewer three-phase interfaces. Due to the vertical melting, the erosion of the pool wall bricks is no longer concentrated at the three-phase interface, but the overall erosion. Therefore, the weak link of the fused corundum bricks is the breakthrough point of erosion.
In view of the erosion mechanism of fused zirconium corundum bricks, the Na2O content in the raw material ingredients of fused zirconium corundum bricks must first be strictly controlled. The national standard requires that the Na2O content in 33#WS should be below 1.45%, and the Na2O content in 41#WS should be below 1.3%. Below, our company’s electric furnace standards require that the Na2O content in 33WS be below 1.35%, and that in 41#WS be below 1.05%.
For the erosion site in Figure 2, the ratio of the riser to the bricks is required to reach 1.5:1. Through the pressure of the riser material, the residual pores in the bricks can be effectively reduced, and the anti-erosion ability of the bricks at the injection port can be enhanced, and the injection port is required. No obvious shrinkage remains.
For the corroded parts in Figure 3, the brick joints are strictly inspected during the assembly process of the fused zirconium corundum bricks and are required to be below 0.3mm. During the kiln baking process, the expansion difference of each part is strictly controlled to ensure the tightness of the brick joints during the process, thereby reducing Gas enters to prevent the formation of a three-phase interface at the brick joints and reduce erosion.
In view of the erosion in the area shown in Figure 4, the width of the bricks is required to be less than 400mm during the design process. Excessive width will lead to excessive shrinkage cavities and loose interior; it is required that the ratio of the riser to the bricks must reach 1.5:1, and the bricks must be discharged through pressure and discharge. The gas rate improves the internal quality of the bricks; reducing heat preservation in the later stages of the kiln operation reduces the erosion rate by lowering the temperature of the bricks.