Title: Masonry procedures and requirements of refractory bricks for cement rotary kiln
Keyword: refractory bricks, MgO bricks, cement rotary kiln
- Masonry procedures and requirements of refractory bricks for cement rotary kiln
Before the brick lining is built, the kiln should be inspected comprehensively, cleaned up, and laid out. The longitudinal reference line of the kiln should be placed at intervals of 1.5m along the circumference, and each line should be parallel to the axis of the kiln. The hoop reference line is placed every 4m, and the construction control line is placed every 1m. The hoop lines should be parallel to each other and perpendicular to the axis of the kiln (take the rotary kiln of qb4.8m as an example)
- Check the packaging and delivery date of the refractory bricks, the general shelf life is 6 months to avoid recurrence of moisture (especially magnesia bricks).
- The basic requirements for bricklaying in the kiln: the brick lining should be close to the cylinder, the brick and the brick should be close together, the brick seam should be straight, the circle should be accurate, the brick should be locked firmly, it should be in a good position, no sagging, no voiding, and the deformed simplified convex part should be polished., The recess should be filled with high-temperature cement.In short, it is necessary to ensure that the brick lining and the kiln body are reliably concentric during the operation of the kiln, and the inner ring surface of the brick lining is flat and smooth, and there is no step phenomenon.
- Requirement for bricklaying varieties in the kiln (recommendation): 0-0.8m kiln entrance special castable; 0.8～8m silico-mo red brick wet masonry, ratio: 322:622=1:4; 2.8～26m magnesia-iron spinelBricks, dry-layed (the deformed and wet-through effect under the first gear wheel belt will be better), ratio: 322:622=3:5; 26～45m silicon-molded red bricks, wet-layed, ratio: 322:622=1:4; 45～601TI silicon-moulded 1680 bricks, 60～71.2m silicon-moulded 1650 bricks, ratio of silicon-moulded bricks: 322:622=1:4; 0.8m high-strength mullite or anti-skinning castable at kiln tail.Keep the cardboard used for expansion joints on refractory bricks when laying bricks.
- The brick joints should be horizontal and vertical, and the deviation of the circumferential joints per meter is allowed to be ≤2mm.
- When laying bricks, use flexible tools such as wooden hammers, rubber hammers or hard plastic hammers to keep the bricks close to the cylinder. Do not use hammers to avoid breaking the bricks. Do not use the bricks with a U-turn on the large end. The small end is allowed 1Turn around, no more than 20mm square.
- When making wet bricklaying, clean water should be used to prepare the fire mud, the amount of water should be accurate, the mixing should be even, and it can be used as needed.The mud that has been prepared for the initial setting must not be used again, let alone used with water
- The fullness of the fire mud during masonry is required to reach more than 95%, and the surface brick joints should be jointed with virgin slurry, but the excess mud on the brick lining surface should be scraped off in time.When wet masonry, the longitudinal seam of the brick joints of each part of the rotary kiln≤2mm
- When locking the bricks, use flat bricks to lock, the adjacent rings should be staggered by 1 to 2 bricks, the processing brick circle of the terminal should be built l~2 rings in advance, and the last locking brick should be finely processed, and it is strictly forbidden to lock the bricks with castable.
- The thickness of the seam steel plate is generally 1-3mm, and it is required to be flat, not crimped, not twisted, and free of burrs.The width of each slab should be less than the width of the brick by about 10mm, the steel plate shall not exceed the brick edge during masonry, and the phenomenon of steel plate sounding and bridging shall not occur.Only one steel plate is allowed to be used in each seam, and narrow steel plates for adjustment should be used as little as possible.1 to 3 pieces of steel plate for each ring of brick joints are allowed. Try not to smash it with a sledgehammer. Use a pneumatic pick thruster to directly push in. The steel plate is not easy to bend
- After the kiln brick lining is completed, it should be cleaned up and tightened as necessary. The rings should be inspected one by one, the rings should be tightened, and the kiln should be kept clean. It is not advisable to turn the kiln after tightening, and should be ignited in time.
- Some manufacturers have experienced red kilns or kiln switching incidents caused by bricklaying not close to the barrel. The red kiln means a certain section of the kiln barrel is dark red. After the kiln is stopped, the refractory bricks are normal, but the red kiln cannot be found.In fact, the section of kiln bricks did not closely adhere to the kiln shell, and the hot gas in the kiln entered the space, causing the red kiln incident.After the kiln bricks were removed, it was found that the inner wall of a certain section of the kiln shell was bright. The reason was that there was a problem with the kiln brickwork. After the rotary kiln heated up, the kiln shell swelled.Simplified, finally polish and thin the cylinder.
- The tertiary duct is lined with masonry. According to the characteristics of the tertiary air duct, it is divided into straight pipes for refractory brick masonry, curved pipe refractory bricks and castable staggered construction, expansion joint castable construction and expansion joints.
- Refractory brick masonry for straight pipes
- Before laying the refractory bricks, pave the calcium silicate board. The calcium silicate board must be laid tightly and there must be no gaps. The refractory bricks must be laid before the calcium silicate board.
- When the calcium silicate board is too wide, it needs to be processed and narrowed so that it can stick to the cylinder and pave the water glass cement.
- Before ring arching, build the lower half circle of refractory bricks, and then support the pre-made arch tires, and then build the upper half circle of bricks. When the last few bricks are left in the ring, pre-lay the bricks and arrange the number of bricks., Lock the bricks, based on the principle of locking, and then inlay a half circle of calcium silicate board.The upper half circle of the four-ring brick close to the castable is wet-laid with high-temperature cement.
- The width of the arch tire should be made 1 to 2 times the width of the refractory brick.
- The arch tires of the vault need to be removed after all the lock bricks are tightened.
- Staggered construction of refractory bricks and castable in the elbow part
- According to the shape of the elbow part, firstly build the refractory bricks that can be built.
- When refractory bricks cannot be built because of the irregular shape of the tube, the castable construction shall be carried out.Castable construction such as expansion joints.Expansion joints, gate valves and other equipment should be prefabricated on the ground before installation. These prefabs have complex geometric dimensions and therefore require strict mold support. The mold is obtained by lofting with metal steel plates.It cannot be deformed during construction, so the mold support must be firm and the position of the support mold must be correct (specific construction according to design requirements).Expansion joints are left.Expansion joints indicated in the drawings shall be reserved in accordance with the provisions of the drawings.