The ladle sliding spout consists of upper nozzle, upper slide plate, lower slide plate and lower nozzle, which is the channel for steel to enter the intermediate ladle from the ladle, and plays the role of sealing the steel flow and regulating the flow. Through the related technical improvement, the service life of ladle upper nozzle is constantly improved, and the slide plate is also realized to be used in multiple furnaces, which not only reduces the consumption, improves the production efficiency, but also reduces the labor intensity of the workers, and provides strong conditions for the progress of the steel making process. However, along with the sliding nozzle life improvement, the risk of steel leakage from the upper nozzle and upper slide plate is also increasing, which seriously threatens the safety of people and equipment. Therefore, the factors affecting the steel leakage between the upper nozzle and the upper slide plate are analyzed, and corresponding improvement measures are formulated. Improve the safety of the use of ladle nozzle and the upper slide plate, reduce the accident rate of the steel plant.
Reasons for steel leakage from ladle upper nozzle and slide gate plate
Between the upper nozzle and the upper slide plate through the sub-mother mouth fit together, through the fire clay or mud pad connection, play a role in sealing the steel water. The direct cause of steel leakage between the upper nozzle and the upper slide plate is the gap between the upper nozzle and the upper slide plate, steel in the static pressure, drilling out from the gap, resulting in accidents. The main reasons for the gap between the water spout and the upper slide plate are: incorrect operation, deformation of the mechanism, the water spout and the upper slide plate is damaged.
Incorrect Handling
- The uppler nozzle is installed incorrectly or too deep. If the upper nozzle is installed into the seat brick, if the position of the upper nozzle is not correct or the depth of the upper nozzle is too deep, the mud gap will be uneven or the mud gap will be too big. If the mud gap is not even, on the side with big mud gap, the upper sliding plate cannot be pressed tightly between the upper sliding plate and the upper nozzle, and the steel is easy to come out from the side with big mud gap during steel pouring process. If the mud gap is big, the same between the upper slide plate and the upper nozzle outlet fire clay force is small, relatively loose, large porosity, after a long time of erosion, the formation of circular grooves, erosion to a certain extent will cause wear steel, resulting in equipment damage, and even injuries to the operator of the accident.
- The fire clay is too thin or the mud layer is too thick. Fire clay is too thin, too mobile, can not fill the gap between the upper sliding plate and the upper nozzle, the mud seam is not tight, once there is not full or defective parts, pouring steel from the weak parts of the steel seepage, serious leakage of steel will cause accidents. In addition, the mud layer is too thick on the sliding nozzle use also has an impact, the fire clay shrinkage rate is relatively large, the thicker the fire clay, after sintering the shrinkage of the size will be larger, so that the slide gate plate and the nozzle will be due to the contraction of the fire clay to produce a gap between the gap, the steel from the gap to seep out, triggering the leakage of steel accidents.
- The surface of the upper nozzle is not clean. The mouth of the water is generally used many times, life from 5 times, 15 times or even 30 times. The higher the service life of the mouth, the more times to clean up, once cleaned up, the surface of the residual steel left behind or the use of fire clay particles within the inclusions will play a role similar to the role of the bracket, resulting in the mouth of the mouth of the fire clay and the upper slide between the compaction, steel in the huge static pressure, from the mouth of the mouth and the upper slide gate between ladle upper nozzle.
- When the upper nozzle is used for the first time, the temperature of the ladle lining is too low, and the upper nozzle creeps into the inner cavity of the seat brick. When the upper nozzle is installed, the outer surface is smeared with an appropriate amount of fire clay, the nozzle brick is squeezed into the lower seat brick, and then the upper and lower slide plates are installed to close the mechanism. If the ladle is put into use without baking, the low temperature of the packet lining will lead to the fire clay can not be hardened in a short period of time, at this time, if the installation of the slide plate, under the action of the spring pressure, the upper nozzle will be displaced in the direction of the seat brick. Resulting in the mud gap between the upper nozzle outlet and the upper slide plate increases, the seal is not tight resulting in steel leakage accidents.
Mechanical deformation
The ladle bottom mounting plate or bracket is seriously deformed. If the ladle bottom is too close to the liquid surface of the intermediate ladle when pouring steel, the ladle bottom and the mechanism will be affected by the thermal radiation of the intermediate ladle liquid for a long time, resulting in deformation. The deformation process will produce stress on the upper nozzle and the upper slide plate, the stress acts on the upper nozzle and the upper slide plate and the direction is not consistent, which will lead to the upper nozzle and the upper slide plate have a tendency to be misaligned, and if the stress leads to the displacement of the upper nozzle and the upper slide plate, it will lead to the loosening of the fireclay, resulting in the leakage of steel.
Damage to ladle upper nozzle and upper slide gate plate occurs
After many times of use of the upper nozzle, because of many times of burning oxygen, the formation of decarburization layer in the aperture of the upper nozzle, the structure of the loose, accelerated the erosion of the upper nozzle. The wall of the upper nozzle is thin, and the damage will be caused at the sub-mouth when cleaning, the more times, the more serious the defect, if the observation is not careful, the slide plate and the sub-mouth of the upper nozzle has a serious defect, which will cause steel leakage accidents.
Mismatch of slide gate plate and mechanism dimensions
The slide gate plate are small in size and appear to wobble in the slide box. After the slide gate plate is used for many times, the surface lubricant of the slide plate wears out, and there will be flaking, steel clamping, erosion, etc. on the surface of the plate. When pulling the slide gate plate, the friction between the plates is large, if the size of the slide plate is small and does not match the cavity of the mechanism, there is a large gap around the slide plate and the inner cavity of the mechanism, under the action of the friction between the plates, the upper slide plate wobbles in the cavity of the mechanism, which will cause damage to the fire clay between the upper slide plate and the upper water outlet, and then leakage of steel.
Improvement measures
(1) Use the upper nozzle installation tool to install the upper nozzle, after installation, require the upper nozzle end face and slide plate installation base plane flat or concave 1~2mm, and require the upper nozzle installed with a locator to tighten it against the upper nozzle installation position until the fireclay hardens and no longer back. 2mm, and require the upper nozzle installed, with the locator will be tightened in the upper nozzle installation position, until the fire clay hardening, the upper nozzle no longer back until. And on the upper nozzle baking, to ensure that the fire clay has been completely dry, the location of the ladle nozzle has been fixed before installing the slide gate plate.
(2)Before using the fire clay, make sure that the fire clay is soft and hard, plastic but not flowing when vibrating, no debris, no dry powder mass, no hard lumps inside, no hard skin on the surface, before use.
(3)Install air-cooling device and heat-insulating plate on the organization, play the role of cooling and heat insulation for the organization, prevent the organization and the bottom of the package from overheating and deformation, to the upper slide and the upper nozzle caused by the external force caused by the leakage of steel, in addition to the organization and the bottom of the package in a timely manner to ensure that the use of timely maintenance and testing to ensure that meet the use requirements.
(4) Reduce the carbon content as much as possible under the premise of ensuring the thermal shock resistance of the upper nozzle. At the same time to improve the density of the mouth of the water, to prevent the mouth of the water due to repeated use, oxygen burning caused by the structure of the loose, flaking off the phenomenon of falling blocks.
(5) Design a reasonable size of the slide plate, to prevent the slide plate in the inner cavity of the institution shaking, in addition to the institution is equipped with a clamping device, play a role in fixing the slide gate plate, to ensure that the slide plate is fixed in the slide box does not move, to prevent the mud joints by the shear, resulting in the fire clay loosening and damage.
All in all, by standardizing the installation operation of the sliding gate spout, improving the mechanism and equipment, and improving the quality of the upper nozzle and the upper sliding gate plate, the actual use of the steel plant shows that the leakage of steel between the upper nozzle and the upper sliding plate has been significantly reduced, and it has got rid of the frequent leakage of steel between the upper nozzle and the upper sliding gate plate that had occurred before and has provided a guarantee for the safe production.