- Time:Nov 03, 2023
High-alumina dense refractory castable is one of the most widely used amorphous refractory products in the modern cement industry. It is often used in cement kiln mouths, kiln door covers, hot sections of grate coolers, etc. The castables in these parts are used in baking or Explosion is prone to occur during the ignition stage.
To address this problem, on the one hand, the quality of on-site construction and baking needs to be improved, and on the other hand, the anti-explosion performance of the castables needs to be improved.
1. Effect of cement addition amount on burst resistance of high-aluminum dense castables
When the cement addition amount increases from 3% to 5%, the anti-explosion temperature of the castable samples does not change, both are 600°C. When the cement addition amount continues to increase to 7% and 9%, the anti-explosion temperature of the castable samples changes from When 600℃ was increased to 700℃ and 800℃, and the cement content was further increased to 11%, the anti-burst temperature of the castable sample was still 800℃, and the anti-burst temperature did not continue to increase.
The main reason why refractory castables burst during reuse is that during the re-accelerated heating process, the stress (mainly water vapor pressure) generated near the reheated surface inside the sample exceeds the ultimate strength of the sample, and the cement increases within a certain range. The added amount can significantly increase the strength of the castable, thereby improving the castable's ability to withstand water vapor pressure, thereby improving the anti-explosion performance of the castable.
Therefore, appropriately increasing the amount of cement added can effectively increase the anti-explosion temperature of high-alumina dense refractory castables.
2. The influence of fiber materials on the burst resistance of high-aluminum dense castables
The anti-burst temperatures of high-aluminum dense refractory castables using polyvinyl alcohol, polyethylene, polypropylene and polyester fiber are 900℃, 600℃, 600℃ and 800℃ respectively. Polyvinyl alcohol has the best anti-burst performance.
Polyvinyl alcohol (water-soluble) has a low water-soluble temperature (80°C). When the sample is heated, the polyvinyl alcohol fiber can produce an exhaust channel earlier. The earlier the exhaust, the pressure generated by water vapor will have a greater impact on the refractory castable. The damage is also smaller.
Therefore, polyvinyl alcohol fiber is suitable to be used as the main explosion-proof agent for high-aluminum dense refractory castables.
3. Effect of fiber length and diameter on burst resistance of high-aluminum dense castables
When the length of the explosion-proof fiber increases from 3mm to 4mm and 5mm, the anti-burst temperature of the castable sample does not change (both are 600°C). When the fiber length continues to increase to 6mm, the anti-burst temperature increases to a certain extent. , reaching 700℃. When the fiber diameter increases from 6 μm to 30 μm, the anti-burst temperature of the castable sample increases to a certain extent. When the fiber diameter continues to increase from 30 μm to 40 μm, 60 μm and 120 μm, the anti-burst temperature of the castable sample does not change ( Both are 600℃).
Explosion-proof fibers that are too short make it difficult to fully disperse when the castable is mixed, and it is more difficult to form a network-like exhaust channel inside the castable, resulting in poor anti-explosion effect. When longer explosion-proof fibers burn out, the channels left behind are longer and easy to interact with each other. The connection forms a channel that communicates with the outside world, which is more conducive to the ventilation of the material and is beneficial to improving the anti-explosion performance. However, the increase in the length of the explosion-proof fiber will lead to poor dispersion of the fiber and poor fluidity of the castable. If the diameter of the explosion-proof fiber is too small, the resistance to bursting will be poor (caused by capillary phenomena), while if the diameter of the explosion-proof fiber is too thick, the number of air permeable channels formed by the fiber will be reduced, which is not enough to form a favorable through-network and will be resistant to the castable. Burst performance is also unfavorable.
Therefore, when the length of the explosion-proof fiber changes in the range of 3-5mm and the diameter changes in the range of 30-60μm, the anti-explosion performance of the high-aluminum dense refractory castable does not change basically.
Through the above analysis of factors affecting the burst resistance of high-aluminum dense castables, the following conclusions can be drawn:
(1) Appropriately increasing the cement content will play a certain role in improving the burst resistance of high-aluminum dense refractory castables.
(2) Explosion-proof fiber materials have a significant impact on the burst resistance of high-aluminum dense refractory castables, and polyvinyl alcohol fiber has a good effect on improving the burst-resistant properties of high-aluminum dense refractory castables.
(3) The length and diameter of explosion-proof fibers have little impact on the anti-explosion performance of high-aluminum dense refractory castables within a certain range.
