Tundish masonry quality improvement plan

 

1. Optimizing the dry material composition and standardizing the fabric

The continuous casting tundish plays an irreplaceable role, and the working layer of the tundish is the basis for protecting the normal and safe operation of the tundish. At present, the material of the tundish is magnesium dry material, and the uniformity of the cloth needs to be ensured, and the uniformity of the cloth of the working layer is the basis for the corrosion resistance of the refractory material. Therefore, starting from the operation, the following optimization schemes are proposed:

(1) According to the research of Chen Changping, the strength of the working layer after demoulding is increased to meet the construction requirements, and the strength after high-temperature firing is reduced to meet the needs of disintegration of residual lining after offline. The amount of resin added in the dry material (w) is controlled at 1% to 3%;

(2) The three sides of the tundish head and the small surface of the tundish must be clothed at the same time, and packing is strictly prohibited;

(3) The bagged materials are stacked in two layers at most. And it is necessary to lay out the first layer first and then the second layer. It is forbidden to spread two bags of materials at the same position at one time; if there is a violation or foreign objects are found in the materials, the tundish is discarded and the cloth is re-laid.


2. Optimization of vibration and baking process

Optimize the vibration process of the tundish, reduce the vibration time from 15 minutes to 8 minutes, and increase the strength of the air pick at the same time to ensure the quality of the slag line; improve the balance of various stresses inside the dry material to ensure the integrity and compactness of the dry material, Improve the quality of the tundish after starting tires. The previous baking time was about 2 hours. After the upper edge of the dry material changed color by 1/2, the fire was stopped, and the cold air was turned on immediately. This caused the reaction temperature of the dry material that was about to harden to be insufficient, and the strength was low, and only a layer of material was formed on the lower part of the dry material. The shell is relatively loose inside. Replace the burner, extend the baking time from the original 2 hours to 3.5 hours, and then turn on the cold air. Since then, the strength of the lower dry material has been significantly improved, and there has been no material drop due to insufficient strength.

3. Optimization of release agent use

The thickness of the mold release agent used for wrapping is thin, causing the working layer to stick to the wrapping, and resulting in cracks in the working layer when the tundish is lifted. Subsequently, the amount of water (w) added to the release agent was reduced from 15% to 10%, the thickness of the release agent was increased to >0.5 mm, and the release agent was increased from 1 application to 2 to 3 times, and the application was even. Avoid tire cracks.

4. Design and application of foam plug

In order to reduce the residual sundries in the nozzle, a special nozzle foam plug is designed for repairing the tundish. Using common foam materials, a frustum-shaped foam plug with a height of 145 mm, an upper bottom surface of ϕ112 mm, and a lower bottom surface of ϕ180 mm is designed to match the shape of the inner cavity of the nozzle seat brick to prevent dry materials from flowing into the nozzle during the construction process, ensuring The shape of the nozzle inlet becomes a regular trumpet shape. As the temperature rises when the tundish is baked, the dry material has a certain strength, the shape of the nozzle inlet is fixed, and the foam plug no longer works. Rely on dry material to increase the anti-scouring and anti-corrosion capabilities around the nozzle, reduce the phenomenon of steel slag blocking holes caused by debris around the nozzle, and avoid vicious accidents caused by blockage of continuous casting machines. After using the special nozzle foam plug for the tundish, the phenomenon of steel slag blocking the eyes is reduced from 2 times per month to 0.2 times, which ensures the efficient and continuous production of continuous casting.

Article Source:Tundish masonry quality improvement plan

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