How to solve problems with ladle slide gate systems?

Due to certain defects in the original ladle slide gate system used in the steel plant, the reliability of the sliding gate mechanism is not strong, and the sliding plate bricks for steel pouring are only used once. This not only increases the labor intensity of workers and the number of turnover ladle, but also is not conducive to the increase of ladle temperature, but also causes the steel pouring system refractory material consumption is high.

In view of this, by improving the ladle slide gate mechanism, adjusting the aperture of the slide plate and improving the quality of the slide plate and other measures, to solve the phenomenon of pulling the steel after the slide gate plate surface is used once, as well as the slide plate stabbing the steel from time to time, to realize the continuous use of the ladle slide plate.

Problems with ladle slide gate systems

1. Slide gate plate diameter

A steelmaking for small billet ladle slide plate diameter <50mm, because of the large diameter, in the process of pouring steel need to switch the ladle slide plate many times. After the use of the slide plate erosion is more serious, the slide plate surface between the phenomenon of steel pulling, can not meet the requirements of continuous use.

2. Ladle sliding plate material

With the increase in the amount of varieties of steel and the improvement of steel quality, steel smelting process needs to add a variety of alloys for processing, resulting in [ Ca ], [ Mn ] and steel slag in CaO, MnO content increases. When using aluminum carbon or aluminum zirconium carbon slide casting these steels, the melt loss at the edge of the slide casting hole is very obvious, showing a deep “horseshoe-shaped melt loss”.

3. Ladle Slide gate mechanism

The slide gate mechanism in the steel plant is a FLK mechanism using gas springs. It is characterized by the possibility of sudden failure, so it should be cooled and pressure tested after each use before use. If it is used continuously, once it fails, a steel stabbing accident will occur, and its reliability is low.

Slide Gate Mechanism
Slide Gate Mechanism

How to solve problems with ladle slide gate systems?

1. Aperture diameter of the slide gate plate

According to the theoretical calculation, it is decided to change the aperture diameter of the ladle slide plate from <50mm to <40mm and <45mm, and the test is carried out. The test proved that: <45mm aperture skateboard can meet the requirements of steel throughput, but also meet the requirements of skateboards for continuous use, and finally determine the aperture of billet ladle skateboards for billet <45mm.

2 .Material selection

According to the actual situation of the production of a steel mill, combined with the use of other domestic and foreign steel mills slide plate, decided to test the metal – nitride combination of slide plate. The raw material of this slide gate plate is corundum as aggregate, metal aluminum powder as matrix, and suitable additives are added. The mixture at the appropriate temperature to make the metal aluminum melting and moderate nitriding firing. Sintered slip sheet with corundum as the skeleton, aluminum metal to form a continuous film wrapped around the particles, AlN as a reinforcing body uniformly dispersed in the matrix to form a fine crystalline structure, endowed with the following characteristics of the slide gate plate:

1) The low expansion coefficient and excellent thermal conductivity of AlN are utilized to improve the thermal shock resistance of the slide plate;

2) The generated AlN tiny particles are dispersed in the matrix, which can hinder the dislocation movement, crack extension, and also has the effect of diffusion toughening;

3) The molten aluminum metal at high temperature is plastic, can fill the pores, while reducing the brittleness of ceramic materials;

4) The antioxidant property of metallic aluminum and AlN and the non-infiltration property of AlN can improve the erosion resistance and oxidation resistance of the slide plate;

5) The nitrided slip sheets have dense body, low porosity, high strength at room temperature and high temperature;

6) The hot strength of the slide gate plate is almost close to the cold strength, which is much higher than that of the aluminum-carbon and aluminum-zirconium-carbon slide plates. This is conducive to improving the performance of the slide plate, and greatly increase the erosion resistance and scour resistance of the slide plate. Tests have proved that the metal – nitride combination of the slide gate plate than aluminum carbon slide plate erosion resistance and scour resistance, the use of good performance. In the billet casting of low alloy steel and slab casting of packaged crystal steel, aluminum carbon slide plate appeared to close the phenomenon of laxity, the slide plate surface pull marks obvious, and the reaming is larger; And metal – nitride combination of all the slide plate can be closed tightly, and the slide plate surface is smooth without pull marks, a small amount of reaming.

3 .Change of sliding gate mechanism

By examining the use of sliding gate mechanism in other domestic steel mills, the steel mill decided to use LSG70-150A1 mechanism instead of FLK mechanism. Due to the original FLK mechanism of the steel plant and Chint LSG70-150A1 mechanism hydraulic system mismatch, can not meet the LSG70-150A1 mechanism requirements. For this reason, a new hydraulic cylinder was specially designed, so that the stroke and the pressure of the hydraulic station are in line with the requirements of Astronergy’s LSG70-150A1 mechanism; and the mechanism linkage was modified, using a rigid linkage to replace the universal joint linkage. After the modification of the slide gate mechanism, due to the Astronergy LSG70-150A1 mechanism of inter-plate pressure, the sliding plate combined closely, can better ensure the reliability of the use.

Ladle slide gate plate
Ladle Slide Gate Plate

In a summary

After the implementation of the above measures, the continuous use of slide plate was fully launched on the steelmaking ladle from the beginning. The rate of continuous utilization reached 62.3% in the same month, and then the rate of continuous utilization of slide plate increased month by month. Billet ladle slip sheet continuous use rate has been stabilized at about 90%. The continuous use of slide plate can reduce the number of turnover ladle, reduce the pressure of ladle supply and turnover;

At the same time, it can also reduce the labor intensity of workers, improve the temperature of the ladle lining, thus reducing the temperature of the steel, and achieve the purpose of production and cost reduction.

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