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The details determine the success or failure. It is most suitable for the construction of refractory castables
The construction of refractory castable is not about painting and art. The quality of our project focuses on technology, and the details determine the quality of the project:
Before construction, it is necessary to check the integrity and cleanness of mixing equipment, transportation tools, vibration tools and parts to be poured; check the water loss prevention measures of formwork, surrounding refractory bricks and thermal insulation layer; check the rust removal, anchor parts, anchor brick form, size, layout, welding quality of equipment and expansion compensation measures of metal anchor parts; Check whether the quality of castable and construction water meet the requirements. In addition, during the castable construction, it is necessary to ensure that there is no power failure and construction interruption.
Among them, the formwork for castable construction is made of non absorbent materials. If wooden formwork is used, waterproof coating shall be applied to prevent water loss of castable. After the loss of water, the fluidity of the castable decreases, so it is difficult to remove the bubbles and vibrate the castable. Steel formwork shall be coated with release agent to prevent adhesion between formwork and castable. When reusing, the formwork shall be cleaned first, then applied with oil, and then used.
① Forced mixers shall be used for mixing. The mixer shall be cleaned in advance and washed with water, and shall not be mixed with lime, silt, Portland cement and other sundries. If the amorphous material combined with superphosphate is stirred, the equipment must be thoroughly cleaned before it can be used to mix the castable combined with cement.
② According to the specifications and construction conditions of the mixer, the mixing amount shall not exceed 200kg each time. Under the condition of specified water consumption, sufficient fluidity of the mixed castable shall be achieved.
③ Pour each component of the castable into the mixer, dry mix for 3min, and then add clean tap water. When adding water, first add 90% of the reference water content of the castable, then slowly add the remaining water to make the fluidity of the slurry meet the requirements, and the wet mixing time shall not be less than 5min.
④ Castables shall be used in a whole barrel and bag. The mixed castables shall be poured quickly, and shall be used up within 30 minutes from the time of adding water. The wet materials that have been initially set shall not be formed by force, and shall not be mixed with water again for reuse, and shall be discarded.
① The model shall be tight to prevent leakage. The castables poured into the mold frame shall be vibrated in layers as soon as possible with a vibrating rod. The thickness of each layer shall not exceed 300 mm, and the vibration interval shall be about 250 mm. Do not vibrate the compacted part repeatedly to avoid segregation.
② During vibration, avoid touching the anchor and damaging the heat insulation layer, and slowly pull out the vibrating rod after the pouring material surface is oozing and most of the bubbles are discharged.
③ Pouring shall be carried out continuously. Before the initial setting of the previous layer of castable, the construction of the next layer of castable shall be carried out in time. If the construction interval exceeds the initial setting time, it shall be treated according to the construction joint requirements.
① For cement bonded castables, when the surface of the castables is dry, immediately cover the exposed parts in the air with plastic or straw bags. However, the chemically bonded castables do not need to cover the surface.
② After final setting, the formwork of the castable can be removed. But the bearing plate can not be removed until the strength reaches 70%.
③ The curing temperature of refractory castable shall be between 10 ℃ and 35 ℃. If the temperature is too high, the hydration product will change into c3ah6, which may lead to the decrease of strength; if the temperature is too low, the hardening will be delayed.
5. Special construction
During the construction in summer, the castables shall be stored in the shade in advance, and the construction shall be arranged in the morning and evening as far as possible. The water temperature and material temperature shall be controlled below 30 ℃. After pouring, timely cover and sprinkle water frequently to cool down.
During winter construction, the castables shall be stored in the room with heating in advance and mixed with hot water to keep the temperature of the mixture above 10 ℃ and the lining temperature above 5 ℃. If these conditions cannot be met, the working environment must be closed, windproof, heated and insulated until it meets the construction requirements. During the hardening and curing period, the castable shall not be frosted.
2、 Construction of daubing ramming materials
Before construction, carefully check whether the construction tools such as molds meet the use requirements, and whether the derusting of equipment, the welding and installation of tortoise shell net and anchor nails are qualified. Only when everything is ready, can we refer to the following construction methods for construction.
① The forced mixer shall be used for mixing. The mixer shall be cleaned in advance and washed with water, and shall not be mixed with lime, silt, Portland cement and other sundries.
② According to the specifications and construction conditions of the mixer, the mixing amount shall not exceed 100kg each time.
③ Pour each component of the ramming material into the mixer, dry mix for 3min, and then add the reference amount of liquid binder. The wet mixing time shall not be less than 5min until the mixture reaches the workable level.
④ The mixed ramming materials shall be used within 15 minutes.
⑤ Wet materials that have been initially set shall be discarded and shall not be mixed with liquid binder for reuse.
⑥ The construction environment temperature shall be between 10-30 ℃. When the material temperature and the construction site environment temperature are too low or too high, appropriate measures shall be taken.
2. Daubing or ramming
① During construction, hammer or rubber hammer shall be used to compact. When applying or ramming, the lining thickness shall be checked at any time. The thickness shall be uniform and the surface shall be flat. Later, use a spatula to wipe out the smooth surface. It is forbidden to brush water, cement slurry or spray dry cement on the surface.
② For lining construction with tortoise shell net structure, the area of lining material filled into tortoise shell net each time should not be too large, and it should be filled one time and tamped one by one to make the lining surface flush with tortoise shell net. In case of construction interruption, the residual materials in the tortoise shell net of the part not under construction shall be cleaned up.
③ Set expansion joint according to construction requirements, and fill the expansion joint with refractory fiber.
① After the completion of construction, natural maintenance shall be carried out under normal temperature for 3 days, and it is strictly prohibited to spray water.
② The maintenance environment temperature shall be above 20 ℃ as far as possible. When the ambient temperature is lower than 20 ℃, the curing time shall be extended or other corresponding measures shall be taken according to the hardening conditions.
① Baking shall be carried out in accordance with the relevant temperature rise curve to avoid rapid temperature rise, otherwise internal damage or bursting will occur.
② When the curing temperature is too low, the baking time should be prolonged and the heating rate should be slowed down.
③ Keep proper ventilation during baking for moisture removal.
④ In the process of oven drying, if there is cooling, do not speed up the heating to catch up.
3、 Kiln baking
In the process of kiln drying, the principle of "slow heating and no turning back" should be followed, that is, slow heating and no cooling, so as to prevent lining damage and improve the service life of kiln lining.
During the lining period, from intermittent to continuous, from low speed to normal speed, the kiln body can be rotated, which can not only keep the temperature uniformity of the lining surface, but also avoid the deformation of the kiln body.