Causes of Refractory Brick Falling off During the Drying Process of New Cement Kiln

Rotary kiln lining brick is an important piece of equipment to ensure the continuity of cement clinker production. Therefore, if the rotary kiln is an important machine, then the refractory brick lining is the motor. However, when many cement factories build a new rotary kiln, the refractory bricks in the kiln will fall off, and they don’t know what to do. What is the reason? The main reason is that the refractory bricks are not locked during the masonry process.

1. Analysis of the causes of brick falling during the drying process of refractory bricks

(1) Improper use of cement. During the masonry process, it is necessary to use refractory mortar to bond the refractory bricks built by the rotary kiln, and it is also necessary to use mortar to level the refractory bricks. When the mortar is applied unevenly, it is easy to cause the model ratio of the refractory bricks to be unbalanced, resulting in the brick surface tilting, and the size of the bricks being inconsistent. The use of mortar has a particularly prominent impact on winter construction. Due to the decrease in the ambient temperature, the fluidity of the refractory mortar becomes poor, and freezing occurs. When the entire ring is locked with grooved steel plates, the mortar has been frozen, but during the heating process of the kiln body, the mortar begins to melt, and the mortar in the brick joints is lost under the gravity of the refractory bricks, resulting in the increase of refractory bricks in the ring joints, loosening and falling off, causing a brick accident.

(2) The locking degree of each circle of refractory bricks is not enough. When laying bricks with a bricklayer, it is often used to lock each circle of bricks in place once. Only when it is properly locked does the next ring start to build. After all the bricklaying is completed, use a sledgehammer to add a joint steel plate on the top of the refractory bricks in the kiln from the kiln tail to the kiln head. This masonry method has a disadvantage: since it is not locked at the beginning, the refractory brick will inevitably slide down under its own gravity, resulting in the refractory brick floor and the inner wall of the kiln not being tight, and there are gaps. When the gap phenomenon is formed, adding the locking joint steel plate will only increase the tightness between the round refractory brick and the brick. When the temperature rises to a certain level, the gap problem will not be changed. When the rotary kiln needs to be turned over intermittently, the gap will be aggravated Phenomenon.

(3) The pressure of the bricklaying machine is insufficient. The working pressure of the bricklaying machine is not enough to support the refractory bricks and make them close to the kiln barrel, resulting in slight voids. During the construction process, it is necessary to ensure that the air supply pressure of the air compressor is between 0.55Mpa and 0.65Mpa, which is our weakness. During construction in winter, due to the long compressed air pipes connected to the masonry machine and the different thicknesses of the connecting pipes, the air compressor has oil-water separator problems, the air storage tank does not often release water, and the connecting pipes leak and other problems. , The air supply pressure of the bricklaying machine is insufficient, and the insufficient air supply pressure will lead to insufficient pressure on the top brick of the bricklaying machine, forming a gap at the bottom of the high alumina refractory bricks.

2. Solutions and preventive measures

(1) When locking bricks, the bottom surface of the refractory bricks of the rotary kiln must be as close as possible to the inner wall of the kiln. After locking one ring, the next ring can be placed. After the masonry is completed, a locking iron plate should be added to the rotary kiln. When tightening the iron plate, the position below the center line of the rotary kiln should be tightened as much as possible to ensure that there are locking iron plates at 90°, 180°, 270° and 360° of the circumference of the rotary kiln, and two slotted plates are allowed.

(2) The supporting mortar for the rotary kiln refractory bricks should be selected before masonry, and its materials, including various physical and chemical indicators, should match the refractory bricks. The mortar that is not allowed is not compatible with the refractory brick material.

(3) Before masonry, set a circular line every 2m in the kiln shell, and the circular line should be parallel to the circumferential weld of each section of the cylinder. When laying the refractory brick floor, it must be constructed according to the axis and ring. Check every 5 circles to measure whether the distance between the ring peak and the circumference line is consistent. Adjust the refractory brick rear ring according to the distance deviation. It is not allowed to reach the designated position in one step but should be adjusted gradually. At the same time, it should be controlled within 2mm.

(4) Try to avoid cutting and processing bricks. If the length of the processed brick is less than the length of the original brick, the adjacent standard brick should be removed. Standard bricks and small processed bricks should be used for staggered masonry to eliminate ring peaks. Wet laying must be used for staggered joint masonry, and high-temperature mortar has a good effect.

Conclusion: It is best to use experienced construction teams for the masonry of rotary kiln refractory bricks. Before the material enters the factory, some acceptance tests should be carried out to prevent the use of unqualified products. Rotary kiln masonry refractory bricks need to undergo static acceptance and dynamic acceptance before delivery to the owner.