high-aluminum castables Archives - Global Refractory Brick Supplier & Factory-Rongsheng

Research on new dry process cement rotary kiln mouth castables and analysis of the effects of various additives on its performance. Rongsheng Refractory Materials Manufacturer specializes in providing high-quality refractory lining materials for high-temperature industrial furnaces. Solve the problem of high-temperature industrial furnace linings, extend the service life of furnace linings, and save production costs for enterprises.

Refractory Castables for Cement Rotary Kiln Coal Injection Pipes and Corundum Silicon Carbide Castables for Front Kiln Entrance

Raw materials: special grade vanadium earth, Al2O3>85%; corundum, Al2O3>92%; calcium aluminate cement; α-Al2O3 powder; silica powder; sodium tripolyphosphate; silicon carbide particles and fine powder.

Basic formula: special grade bauxite, 5~8mm accounts for 12%, 3~5mm accounts for 23%, 1~3mm accounts for 15%, <1mm accounts for 20%. Corundum fine powder, SiC fine powder, and binder account for 30%.

Wear-Resistance Corundum Silicon Carbide Castable

(1)Amount of SiC.

The component of silicon carbide is SiC, which appears in colors such as green, black and yellow due to impurities. It is a covalently bonded compound with strong inter-atomic bonding force and has the characteristics of high melting point, high hardness, high strength and low expansion, high thermal conductivity, high electrical conductivity, and strong chemical properties.

(2) Amount of cement.

Cement is one of the important components of refractory castables. It is an important material that determines strength and also affects other properties. Different types of cement and their dosage have different effects on performance.

CA-80 cement refractory castable uses relatively pure CA-80 cement as a binding agent, and is mixed with corundum, mullite, special grade bauxite clinker and alumina powder and other bone powder materials or admixtures in proportion, and add water Made after mixing, shaping and curing. It is characterized by high refractoriness and load softening temperature, high high temperature strength, strong slag resistance and resistance to reducing gases.

(3)Amount of silica powder.

Microsilica powder is an aggregate of a large number of solid particles and belongs to the category of powder materials. Its properties mainly include particle size and distribution, particle shape, density, melting point and chemical composition, particle fluidity, filling, cohesion, consolidation and physical and chemical changes at high temperatures, etc.

In refractory castables, the basic mechanism of action of silica powder is filling. Improved workability, resulting in increased fluidity, increased volume, and reduced apparent porosity. Therefore, the strength of refractory castables has been significantly improved, and other high-temperature properties have also been greatly improved.

(4)Amount of gel powder.

Gel powder is a kind of retarder, used as an admixture for amorphous refractory materials. Refers to materials that increase mass by less than 5% and can improve the performance and workability of basic constituent materials as required. Its main function is to form complexes, inhibiting the hydration reaction and the formation of hydrates. That is, the positive ions dissociated from the retarder and the binding agent form a complex, which inhibits the formation of hydrates or the crystallization of the hydration reactants. Or it inhibits the growth of hydrate phase grains, thereby delaying condensation and hardening. The adsorption film is formed and the cement particles are wrapped, that is, the retarder is adsorbed on the surface of the cement particles and forms a film. It prevents cement particles from contacting water, inhibits cement hydrolysis and hydration reaction speed, and thus plays a retarding effect.

Effect of Various Components on the Performance of High Aluminum Castables

(1) Add SiC to high-aluminum castables to increase strength and wear resistance. Especially the high-temperature performance is enhanced.
(2) As the addition amount of silicon carbide increases, the normal and high-temperature strength of the castable increases first and then decreases. The appropriate addition amount of silicon carbide is 3%.
(3) Adding cement to high-aluminum castables can significantly increase its flexural and compressive strength and reduce its bulk density.
(4) Comprehensive analysis of the impact of cement blending on its physical properties shows that the best cement blending amount (w) is 5%.
(5) Different types of cement are mixed with different physical properties.
(6) Add silica powder to high-aluminum castables to significantly increase its strength.
(7) Comprehensive analysis of the impact of the blending of silica powder on its physical properties shows that the best blending amount (w) of silica powder is 4%.
(8) When different types of silica powder are incorporated, the changes in physical properties are related to the changes in SiO2 in the silica powder. The flexural strength and impact strength of materials with high SiO2 content are higher, the water absorption rate is correspondingly lower, and the volume and mass are larger.
(9) Add cement and silica powder to high-aluminum castables to significantly increase its strength.
(10) Comprehensive analysis of the impact of the blending of cement and silica powder on its physical properties shows that the best blending amount (w) of cement and silica powder is 5% + 2%.
(11) Using gel powder as a binding agent, the mechanical properties are significantly enhanced at high temperatures.
(12) As the content of gel powder increases, the normal and high-temperature strength of the castable first increases and then decreases. The appropriate additional amount of gel powder is 4% (w).

Is it normal for the castable to have cracks after the oven-drying? What are the reasons?

Under normal circumstances, after the oven-drying is finished, the kiln can operate normally after passing the project acceptance, and the castable can reach its own performance within the use temperature range. There are three main reasons for the cracks in the castable after the oven-drying.

The amount of water added is not well controlled when the high-aluminum castable is wet mixed and stirred. Adding too much water leads to insufficient bonding of the castable, which causes the castable to fall off. Adding too little water will greatly weaken the performance of the castable. Therefore, the amount of water added must be added in proportion and strictly in accordance with the instructions on the instructions.

When curing high-aluminum castables, the curing time is not enough, resulting in the failure of the strength of the formed castables. Under normal circumstances, when the temperature is higher, the curing time of the castable is 24 hours. In colder winters, the curing time of castables is 48 hours. Due to the low temperature, a small amount of coagulant will be added to speed up the setting speed of the castable.

When the castable is in the oven-drying, the temperature rises too fast. When the castable is in the oven-drying, the boiler heating curve must be controlled. When drying the furnace, the construction personnel will often formulate the furnace curve according to the boiler situation. In the oven-drying, strictly control the heating temperature to avoid the phenomenon of rapid heating and rapid cooling.

After baking, if the cracks in the castable are not obvious or serious, it needs to be checked in time and repaired with the same castable. If the crack is large or the castable falls off, the construction personnel need to make a solution to the problem. And it needs to be repaired with new castable.

The oven-drying after the construction of the high-aluminum castable is a very important factor. Similarly, when purchasing castables, how to purchase high-quality high-aluminum castables is also very important.

High Alumina Castable - Rongsheng Supplier

Rongsheng High Alumina Castable for Sale

How to distinguish the quality grade of high aluminum castable?

High-alumina castable is the most used castable among refractory castables. The quality grades of high-aluminum castables produced from different raw materials are not the same.

How to distinguish the quality grade of high aluminum castable? By the manufacturer, there are many methods, the most important of which is to distinguish from the aspects of aluminum content, body density, porosity, compressive strength, and load softening temperature.

First, it is the index of aluminum content. The higher the aluminum content of the high-aluminum castable, the higher the quality level of the castable. The high aluminum content indicates that the raw materials used have high purity and low impurities.

Body density is also an important indicator of the quality of high alumina castables. The higher the volume density, the higher the density of the high-aluminum castable, the higher the wear resistance and erosion resistance. The bulk density and porosity of high-alumina castables are also closely related to the composition of the raw materials.

The flexural strength at room temperature is the ability of high-aluminum castables to withstand bending. Moreover, flexural resistance plays a decisive role in high-temperature strength. The higher the purity of the raw material, the higher the bending resistance and the higher the temperature it can withstand. Therefore, the flexural strength is also a way to distinguish the priority of castables.

The compressive strength at room temperature can also indirectly show the wear resistance and impact resistance of high-aluminum castables. The higher the strength, the better the abrasion resistance, erosion resistance, and erosion resistance. The load softening temperature of high aluminum castables is also an item that cannot be ignored. The higher the load softening temperature, the lower the probability of deformation of the castable. The high softening temperature under load is sufficient to prove the structural strength of the castable under the conditions of use.

The performance indexes of aluminum content, bulk density, and load softening of high-aluminum castables are the best way to distinguish castables. When selecting high-aluminum castables, different grades of castables should be determined according to the use temperature and the degree of acid-base corrosion. This makes the best use of it, and also reduces costs reasonably.