Low cement castable is a new type of castable. The usage of cement is low. Generally, it can be divided into aluminum silicate, mullite, corundum, magnesia-aluminum, sharp stone, carbon and silicon carbide. Wait for these kinds of types. So, what are the characteristics of low cement castables? What are the specific applications?
1. The characteristics of low cement castable
1. Improve refractoriness and high temperature strength
Due to the low CaO content in low cement castables, it can reduce the formation of eutectic phases in the material, thereby improving refractoriness, high temperature strength and slag erosion resistance, especially for cement-free castables.
Yuanling low cement castable
2. Low porosity, high volume density
The mixing water used in the construction of low cement castables is only 1/2 to 1/3 (about 4% to 6%) of ordinary low cement castables, so the porosity is low and the bulk density is high.
3, less cement hydrate is formed
Low-cement castables produce little or no cement hydrates after molding and curing. There is no phenomenon that a large number of hydration bonds are destroyed during heating and baking, which will reduce the strength at medium temperature. Low-cement castables will gradually sinter as the heat treatment temperature increases. , The intensity will gradually increase.
4, improve the stability of the lining structure
Low-cement castables integrate the characteristics of traditional refractory materials and adopt ultra-fine powder application technology to improve the mid-temperature strength and high-temperature volume stability of the castables, so that the product's organizational structure forms a strong anchor-like multi-directional crystal structure at high temperatures. The stability of the overall structure of the lining body is ensured, and the service life can be increased by 3 times compared with traditional castables.
2. Application of low cement castable
Low cement and very low cement refractory castables have been widely used and promoted in industrial kilns in the metallurgical industry, petrochemical equipment, mechanical equipment manufacturing and decorative building materials manufacturing industries at this stage, and have achieved good results and Economy Profit. The specific applications of different types of low cement castables are as follows:
1. Clay and high alumina low cement castables can be used as linings for various heat treatment furnaces such as hot blast furnaces, heating furnaces, soaking furnaces, and rotary kilns.
2. Mullite-based low-cement castables are used for various high-temperature burner linings, heating furnace water-cooling pipe wrapping linings, etc.
3. Corundum and chromium-containing corundum-based low-cement castables are used for the lining of certain parts of the refining device outside the molten steel furnace. It is also used for the high-temperature wear-resistant lining of the petrochemical catalytic cracking reactor in the industrial frequency induction furnace.
4, Al2O3-SiC-C low cement castables are used as linings for blast furnace tapping troughs, iron furnace tapping troughs, and integral spray guns for the normalization of molten iron.
5. Refractory and low-cement refractory castables containing Cr refractory can be used as the lining of the triangular area of the top of the iron-making electric arc furnace and the lining of some components of the scouring equipment outside the molten steel furnace, such as the overall spray gun lining for the spray metallurgical industry, RH and DH vacuum pump degassing device and prepreg tube lining, direct current induction furnace lining, high temperature and abrasion resistant lining of petrochemical equipment catalytic cracking tubular reactor, etc.
6, MgO-AI2O3 quality or AI2O3-MgO.AI2O3 quality low cement castable is used as the lining of ladle and tapping trough.
Three, the use of low cement castable matters needing attention
1. Allocate castables according to a certain proportion
When using low-cement castables, pay attention to the method of blending. The proportions must follow the corresponding regulations. Do not add water or add castables arbitrarily. Once the proportions are wrong, the casting effect will be greatly reduced. Therefore, the operator of the castable must have rich experience and be able to complete the deployment of the castable in a reasonable proportion to ensure the smooth progress of the follow-up work.
2. Use the evenly stirred castable as soon as possible
In the actual application of low cement castables, many customers mix the castables evenly and dry them aside without using them in time. The disadvantage of this is that the low-cement castable exposed to the air will evaporate more water, which will reduce the moisture content of the castable, which is not conducive to the use of the castable.
3, the storage of castables should be dry
If the amount of low cement castables purchased is large, they need to be stored in a relatively dry environment in time, and corresponding protection work should be put in place to ensure that the castables are not affected by external air and avoid quality damage. Take a proper amount before use, do not put all the castables on the construction site, this action will interfere with the storage of the castables.
4. Formulate a reasonable oven curve
The outstanding feature of low cement castable is its compactness and high strength, which brings benefits to the use, but it is prone to peeling or bursting if it is baked improperly. Therefore, it is very important to formulate a reasonable oven curve. If necessary, an excellent anti-explosive admixture can be used, so that the moisture of the low cement castable molding weight can be removed smoothly without causing any side effects.
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