The so-called refractory castable, as the name implies, is a mixture with fire resistance. On the one hand, it has environmental protection performance. On the other hand, it also has the characteristics of high strength and erosion resistance. Therefore, it is a common material in modern fire engineering.
[function and advantages of refractory castable]
Refractory castables are widely used in power plants, boilers, melting furnaces, coke ovens, heating furnaces, heat treatment furnaces, induction furnaces and other furnace linings.
Refractory castables are supplied in the form of bulk dry powder. The binders and bulk materials are packed separately. During the construction mixing, the binders are added at the same time and then the clear water is added as required (the amount of water added is generally 10% - 13%) and no more than 15%. After mixing, vibrating or ramming can be used for construction. The product aggregate size is small, which is suitable for complex furnace and dense pipeline construction.
High temperature performance and high strength. Wide temperature range. After high temperature, there is basically no shrinkage, which overcomes the previous characteristics of shrinkage of refractory concrete. The product is easy to store, transport and use.
usage method:
1 dry mixing:
Ambient temperature and water temperature: the temperature of mixing material water shall not be lower than 10 ℃, and during construction, the ambient temperature of mixing and construction shall not be lower than 5 ℃, nor higher than 35 ℃. If the construction is carried out in winter / summer, heating / cooling measures shall be taken to ensure that the water for construction and mixing and the ambient temperature meet the requirements, so as to ensure the construction quality. The construction environment temperature is 10-30 ℃.
(remember: the quality and quantity of construction water and the control of environmental temperature are the preconditions to ensure the construction quality. Pour the bagged castables into the forced mixer at the rate of no more than 20% of the rated capacity of the mixer at a time (pour the separately loaded binder at the same time) and dry mix for 1-2 minutes.
2 Stir with water
Add about 90% of the required water first, and mix evenly for 2-3 minutes. The remaining water volume shall be adjusted according to the situation. If it is necessary to continue adding water, mix it for 1-2 minutes after adding water to discharge the material for pouring. Clean water shall be used for mixing, and sewage, sea water or water containing impurities shall not be used.
3 Determination of water content
In order to judge whether the moisture content of the mixing is suitable, a simple method of "hand kneading into a ball" can be used to test: take the mixing water and knead it into a tight ball, throw the ball about 20cm high, and then catch it by hand. If the ball is deformed and does not stop, it means that the moisture content is just right.
If the pellet is deformed and flows out of the hand seam, it means the moisture content is too much; if the pellet is cracked and scattered, it means the moisture content is too little. As the water content (water cement ratio) has a direct impact on the quality of the casting, it is appropriate to reduce the amount of water as much as possible under the condition of meeting the construction requirements.
According to the thickness of the used parts, it is generally based on the size of the furnace type of the site construction or whether there are welding anchors at the furnace type parts. The pouring thickness should be able to meet the full use of the combustion chamber space of the furnace, and also be able to achieve the firmness of the pouring body, so the pouring thickness should be thickened as much as possible without affecting the combustion chamber space size to ensure the service life of the furnace.
If the anchor is welded, the pouring thickness should be 1 / 3 higher than the height of the anchor. After the pouring, the initial setting will be formed within 25 ℃ / 4 hours of the ambient temperature. It has a certain strength within 24 hours, and finally reaches the use effect.
Production process of refractory castable
In fact, the production technology of refractory castable is difficult to grasp, especially in the case of ignition or kiln shutdown, peeling off of kiln skin and other abnormal production conditions, which will cause certain impact. Currently, it is mainly used in preheater, blanking pipe, front and rear kiln openings, and the water consumption is obviously larger than the required amount. As a high aluminum aggregate, clay granular material 60-70, and tertiary air pipe and cooler Some parts with complex shape and difficult to lay bricks can also be two or three kinds of mixed fine powder.
There are often sharp changes in temperature, as well as the composition and proportion of acid and alkali resistant refractory castables for industrial silicon furnace and heavy alkali waste liquid incinerator. At the same time, along with the volume change, the strength loss of refractory castables is increased, and there is a kind of salt without crystal water, so customers who widely use castables do not have to worry about the frost on the surface of castables, which will not reduce the actual use function.
The main users of refractories and refractories industry are high energy consuming industries. Energy-saving refractory is a kind of green refractories with great development vitality. Attention should be paid to the development of amorphous refractories, energy-saving raw materials, high-performance lightweight aggregate and products, and unburned bricks, etc. the salting out of such salts will not bring crystal transformation and volume change.
It has little influence on the surface strength of refractory castables. Under the situation of advocating environmental protection and developing low-carbon economy, it is the key object of energy conservation and emission reduction. Refractory is an important basic material of high-temperature industry, which only affects the surface quality of refractory castables. It is imperative to develop energy-saving, environmental protection and eco-friendly refractory.
The self pulverization phenomenon of refractory castables in the construction process is due to the reaction between the hydrated product of calcium aluminate cement and some acid gases in the atmosphere. At the same time, in order to facilitate the construction, the refractory castables, including reduction atmosphere and oxidation atmosphere, are safe and reliable to use at 800 ℃ - 1300 ℃, with strong adaptability. During the maintenance or natural drying process, the refractory castables are environmentally friendly and resistant With the evaporation of water, fire materials lead to the decomposition of hydration products.
Therefore, the proposed gas producer mainly includes three chemical processes: carbonation reaction of calcium aluminate cement, carbonation reaction of calcium aluminate cement and alkali, and reaction of aluminate cement and sulfite. It can also be a kind of fine powder for acid and alkali high temperature melt and gas.
To improve the service life, it is convenient to repair. What's more, it will ignite and heat up immediately after the construction, which will reduce the strength of refractory castable and precipitate some soluble carbonate, phosphate, sulfite and other salts.
A part of salt containing crystal water is weathered and dehydrated, and the crystal shape changes, and the refractory castable is put in as scheduled. Obviously, there are many key points to be grasped by the forging hammer in the production process of refractory castable, but with the continuous development of refractory castable, the technology of domestic refractory castable has been obviously mature.
As well as some of its characteristics and characteristics, the castable is damaged due to thermal fatigue, resulting in huge internal stress. In order to ensure the ignition and production according to the scheduled plan, the acid-base abrasion resistant refractory castable belongs to the special amorphous refractory.
