The leakage of ladle sliding nozzle system will affect production and safety. This paper analyzes the reasons for leakage, including mechanical, sliding plate material, and process operation problems, and proposes improvement measures such as strengthening mechanism maintenance, tracking sliding plate quality, and reasonable operation.
The ladle sliding nozzle is an important system for controlling steel production. If the system leaks steel during use, it will seriously restrict the stable and smooth production and threaten the safety of personnel and equipment. This paper analyzes the various factors that affect the steel leakage of the ladle sliding nozzle system and formulates corresponding improvement measures. Through the improvement, the steel leakage accident of the ladle sliding nozzle is effectively controlled, which promotes the stability of steel production.
Analysis of the cause of steel leakage from ladle slide
Slide plate leakage caused by mechanical reasons
⑴The deformation of the bracket or the overuse of the spring will cause uneven pressure on the slide brick surface, with one side bearing more force and the other side bearing less force.
When the pressure of the molten steel exceeds the pressure on any side, the molten steel will enter between the two slides, causing steel to be clamped or leaked.
⑵The slide bar falls off or the lower rotary sleeve loosens, resulting in insufficient pressure on the plate surface, which can easily cause the gap between the clamp steel and the slide plate to increase during flow control, eventually causing steel leakage.
The slide bar problem also causes the trolley to run unevenly, and the lower rotary sleeve loosens, causing the lower slide plate to sink, which will cause gaps between the plate surfaces.
Skateboard leakage caused by skateboard material
⑴When pouring calcium-treated steel or high manganese steel, the upper water inlet and the slide bricks have poor corrosion resistance, the water inlet and the slide expand quickly, and the effective stroke of the slide becomes smaller, which can easily cause cast-water outage or steel clamping on the plate surface.
⑵The upper and lower slide bricks have low strength at high temperatures and poor resistance to “thermal shock”. Before pouring, the high-temperature molten steel on the plate surface produces a strong “thermal shock”, resulting in tensile stress exceeding the strength of the slide, forming radial cracks centered on the pouring hole.
⑶The working surfaces of the upper and lower slide plates have poor high-temperature wear resistance, and the sliding surfaces are prone to “roughening”.
After the molten steel penetrates, the “roughening” phenomenon intensifies when pushing and pulling, and the friction resistance of the slide plate increases. In severe cases, steel leakage will occur between the sliding surfaces.
Slide plate leakage caused by improper process operation
⑴ During the assembly process, there are mainly the following reasons.
When the upper slide plate clamps the mud pad, the visual error of the gap may cause the mud pad to be improperly measured. If it is too little, there may be a gap between the upper water inlet and the slide plate, causing steel leakage or steel clamping problems; the water inlet seat brick has low high temperature strength and is easily damaged when using a pneumatic pick for heat exchange, resulting in increased gaps and steel leakage accidents.
The water inlet brick is easy to crack under heat and molten steel pressure, and the refractory material will break in severe cases.
⑵Because the sintered layer of drainage sand was too thick, the sintered layer broke when the molten steel was poured, resulting in the reverse steel and the sliding trolley wheels sticking to the steel.
This destroyed the pressure balance, increased the gap on the plate surface, and caused the steel leakage accident.
⑶The single-flow accident of the square billet leads to a longer steel drawing time, and the sliding nozzle is frequently opened and closed during the semi-flow casting of the large ladle, resulting in serious erosion of the plate surface.
When the sliding nozzle is semi-flowing, the lower slide brick is washed by the molten steel to form a groove. When the ladle is closed, the molten steel condenses in the groove, resulting in steel clamping between the two slides. Frequent flow control expands the clamping steel, which is prone to steel leakage accidents.
Improvement measures for steel leakage from ladle slide
1、Strengthen the maintenance of the sliding gate mechanism and do a good job in the offline management of the sliding gate mechanism; especially for the parts that are easy to wear and deform, such as slide bars, small wheels, and springs, keep track of the service life and replace expired parts in time.
2、Strengthen the maintenance of the sliding gate mechanism and do a good job in the offline management of the sliding gate mechanism; especially for the parts that are easy to wear and deform, such as slide bars, small wheels, and springs, keep track of the service life and replace expired parts in time.
3、Track the quality of skateboards, record the usage of each batch of skateboards, organize and analyze photos of broken bricks after use, and do a good job of evaluating the skateboards; try out skateboards in advance when changing batches, formulate continuous sliding rate according to the use effect, and ensure the rationality of indicator formulation.
4、For the first furnace being poured, for continuous pouring of molten steel after a single-stream accident in a billet, or for ladles that require long-term steel pressing by production organizations, continuous sliding slides must not be used to reduce the risks brought about by abnormal operations.
