Construction Scheme of Refractory Brick Masonry for Rotary Kiln

2023-08-12 16:28:52

Masonry Requirements for Refractory Bricks in Rotary Kiln
1. The brick lining is reliably concentric with the barrel.
2. Grasp the construction quality of the brick lock area.
3. Minimize the amount of steel plate used.
4. Correctly handle the brick joints.
5. Brick joints should be horizontal and vertical.
6. It is strictly forbidden to use a hammer to lay bricks.

Masonry method of rotary kiln
1. Ring reduction/and wrong/5 cut
According to the different brick joints, the blasting method of cement rotary kiln refractory bricks is divided into two types: circular and staggered. It is better to build the cylinder with bricks and rings. The advantage of ring masonry is that it is easy to build and dismantle, but it is necessary to ensure that the brick type and the size of the brick joints meet the requirements. If the brick joints are too large, it is easy to cause dislocation and deformation of the kiln lining and even accidents such as drawing lots and falling bricks. If the brick joint is too small, the lining brick will be damaged in advance due to excessive thermal stress during use. The main disadvantages of the staggered masonry method are: first, it is difficult to build masonry and partial repair; second, the quality of masonry is not good for bricks whose size and shape are not regular. At present, this method is only used on some small rotary kilns where the maintenance period is very long.

2. Dry and Wet
Dry masonry refers to mainly using steel plates and lock bricks to build bricks for rotary kilns, and only a small amount of fire clay is used to build bricks when it is not possible. Wet laying refers to mainly using fireclay to lay bricks, and steel plates are only used when locking bricks. In general, alkaline bricks mostly use dry laying. In particular, dolomite bricks can only be used in dry guns due to easy hydration. The advantage of dry masonry is that the masonry speed is fast, but it has strict requirements on the shape and size of the bricks, and the integrity of the lining is poor, which is prone to stress concentration and crushed bricks. Therefore, when encountering irregularities in the shape of the kiln body, or gaps caused by brick shape size errors, try to fill them up with fire clay. In general, aluminum-silicon materials are mostly used for wet laying. Because the coefficient of thermal expansion is low, it is easier to draw lots and drop bricks. Therefore, it is necessary to use clay to bond bricks to improve the integrity of the lining. The use of high-strength phosphate fireclay for masonry is an effective measure to improve the integrity of aluminum-silicon refractories and prevent drawing lots and falling bricks.

The characteristic of the ring masonry method is that each individual brick ring is tightly built and can exist independently and stably. This is not only beneficial to construction and inspection but also beneficial to dismantling and overhaul, especially beneficial to the brick lining used for laying bricks frequently replaced. The characteristic of the staggered masonry method is that bricks are interlaced with each other, which can effectively reduce the trouble of frequent brick dropping in small kilns with irregular kiln bodies. But the method’s masonry and overhaul are all inconvenient. At present, the shape regularity of domestic refractory bricks is not good enough, and the quality of brick linings built by this method is difficult to guarantee, so only a small number of kilns use the staggered masonry method.

Masonry Inspection of Refractory Materials for Cement Rotary Kiln
After the refractory masonry of the rotary kiln in the refractory material factory is built, it needs to be carefully checked. There is no adhesive between the dry-laid refractory bricks, and there may be a phenomenon of loosening of a single brick, which should be checked by a 90-degree rotation and ups and downs. The loose part is wedged into a 2mm thick steel plate to tighten it. The loose parts should be marked and wedged tightly when transferring to the upper part. Only one steel plate is allowed to be wedged in each seam. If the masonry is loose, it should be wedged at 4 to 5 bricks of the first steel plate at intervals, and then wedged in the second steel plate. The steel plate should try to be fully wedged. If it cannot be wedged in, use a gas-cutting gun to cut off the leaking part.

The masonry plan to be lined should be properly arranged, and the kiln should be fired and put into production as soon as possible after the masonry is completed, mainly because:
1. After the masonry of the kiln shell is completed, the load is greatly increased, and it will be fatigued and deformed under the action of static load.
2. When the alkaline brick is left for a long time, the malignant transformation of MgO to Mg(OH)2 occurs due to the absorption of water, and it is damaged due to volume expansion. This is true for magnesia bricks, especially for dolomite bricks.
3. The dry-laid refractory bricks will undergo directional compression and sink, and the upper refractory bricks will loosen. If it is impossible to incinerate immediately, the kiln body should be rotated slowly to adjust its position regularly to avoid deformation of the kiln body. For dolomite bricks, the method of sprinkling quicklime is adopted to prevent the dolomite bricks from being damp and reduce the quality of refractory bricks and shorten the service life. Before incineration, carefully check the looseness of the kiln lining, and use steel plate wedges to tighten it if necessary.

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