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[Original Article] Production practice: Summary of golden ideas in continuous casting workshop

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  • Argon gas adjustment during continuous casting

Argon blowing, argon blowing, the upper (water) port is generally not as big as a stopper;

The pulling speed changes, the large and small change to blow argon, the goldfish spit out and see “ghost fire”, and the liquid level data is set high.

Better argon blowing state of the copper mould tube

The principle of continuous casting argon blowing is:

  1. Under the condition that the liquid level in the copper mould tube is not tossing, it is best to blow argon with the stopper rod, and it is better to blow argon from the upper nozzle, and the stopper rod. The amount of argon blowing should be as large as possible;
  1. When the limiting displacement bar rises or the liquid level fluctuates, check the SEN or the water inlet is blocked or not. If the SEN blockage is not obvious, please readjust the flow rate of the upper nozzle is more important than blowing argon with a plug.
  2. Always pay attention to the liquid level detection data of the mold, and realize the liquid level fluctuation of ±3 mm is the ultimate goal of continuous casting argon blowing. According to the liquid level detection data, the argon blowing flow should be adjusted at any time. The argon adjustment is summed up as a phrase.
  3. As the drawing speed changes, the amount of argon blowing is always adjusting and changing. Generally speaking, the higher the drawing speed, the larger the flow of argon blowing. The flow rate of argon blowing at low drawing speed is also reduced.
  • continuous casting contractor operation post

1.Manipulator, long nozzle; clear and two straight, go straight down!

Summary of golden ideas in continuous casting workshop

 

One cleaning: clean up the remaining refractory gaskets on the long * mouth, and clean them thoroughly;

Summary of golden ideas in continuous casting workshop

Two positive: Refractory sealing gasket is placed, the upper nozzle is aligned with the ladle lower nozzle

Summary of golden ideas in continuous casting workshop

Go straight down: the long nozzle goes down vertically, try to dip into the liquid surface of the tundish as quickly as possible

 

2. The tundish was checked, and a working layer collapsed.: After each furnace was subcontracted, the lower part of the nozzle was broken.

 

3.Connect the ladle and observe well: the wall of the ladle is red and refuse to be packaged, and the steel is hung along the side of the ladle to confirm.

From whether a furnace of molten steel can be put on the turntable to strictly protecting the pouring during the pouring process, the ladle position plays a key role as a gatekeeper and a link between the past and the future, and the impact on the quality of the slab is particularly important. Protection of ladle pouring. Pouring measures include immersion shroud, argon blowing and covering agent, etc. After pouring in each furnace, the shroud bowl must be filled

Use an oxygen-burning lance tool for cleaning, so that it is easy to inhale the air and cause the molten steel to increase nitrogen and secondary oxygen.

In addition, oxygen burning causes the refractory material to erode the nozzle bowl. In addition, the use of continuous water slides in the large package results in gaps between the upper and lower nozzle contact surfaces during the pouring process, which causes nitrogen increase and secondary oxidation due to air inhalation, which affects the quality of cast slabs. Serious impact. The contractor Zhou Dehu found that the gasket material left on the bowl and the upper nozzle surface after pouring in each furnace could not be cleaned up even with an eye-burning gun, which caused oxygen absorption. Therefore, Zhou Dehu made a special cleaning of the nozzle bowl and upper nozzle residual gaskets by himself. Tool of. After using this tool, it is ensured that there is no residual debris between the upper and lower nozzles and the gap is guaranteed, the stability of the seal is guaranteed, the good protective casting is ensured, the nitrogen addition and secondary oxidation are effectively controlled in continuous casting, the quality and performance of the casting slab are improved, and the guarantee On-time fulfillment of various steel contracts and improvement of quality.

 

4. If you want to pour surplus steel, fill the tundish with steel first, and don’t panic when shutting down the steel. There is slag under the hand feeling vibration, the flow is closed and the flow is opened, the slag layer of the tundish is well controlled, and the slag layer of the covering agent is added.

Consumption of continuous casting iron and steel materials includes the surplus weight at the end of large ladle pouring, the surplus weight at the end of tundish pouring, and the weight of slab waste. At present, the number of production furnaces of two continuous casters in each shift is more than 20 furnaces. Therefore, as a large contractor, the control of the surplus at the end of the pouring of each furnace and ladle is particularly important to reduce the consumption of steel materials. How to reduce or even no remnants of steel while ensuring that the ladle does not contain slag is the difficulty of the ladle pouring operation and the breakthrough to reduce the consumption of steel materials. According to many years of ladle pouring experience, when the pouring of ladle with little remaining steel is about to end, because the steel flow is accompanied by steel slag, the shroud manipulator always vibrates.

In view of this fact and law, the following operations can be carried out: it is found that the tundish is filled with about 30-40t in the final stage of the pouring of each furnace, and then the steel flow of the large ladle is turned off to let the tundish tonnage decrease slowly, and the tundish is closely observed. When the liquid level drops, feel the vibration of the manipulator by hand. If the vibration stops-it means that there is no molten steel in the ladle and no steel flow into the shroud, and then immediately close the sliding nozzle. In this way, it can be achieved that there is no residual steel at the end of the ladle pouring, and the accuracy of the control of the ladle pouring residual can basically guarantee zero residual steel. It greatly reduces the consumption of steel materials in continuous casting production, guarantees the volume of molten steel per furnace, and reduces the production cost of steel plants.

 

  • Continuous casting tundish baking

For high nozzle temperature, Lava jet acceleration

Summary of golden ideas in continuous casting workshop

Reducing the baking time of the continuous casting tundish and increasing the baking temperature of the continuous casting tundish are the keys to reducing the temperature drop of the molten steel and increasing the success rate of pouring. Although the previous continuous casting tundish nozzle baking furnace can basically reach the baking time The baking temperature but the low temperature increases the risk of bursting of the tundish nozzle during pouring. Sometimes the tundish nozzle is darker after baking and the baking time is deliberately extended. In order to reduce the baking time and reduce the problem of the tundish nozzle bursting during pouring, we designed the original SEN baking nozzle to increase the length of the nozzle, thereby increasing the spray speed of the Laval nozzle and increasing the negative suction drying The negative pressure of the oven can more powerfully guide the flame in the tundish to the nozzle of the tundish for baking. Figure 1,2 is the comparison of two different SEN baking nozzles during the baking process, pay attention to the improved nozzle of Figure 2. The tube body is blushing red, the SEN baking temperature is also higher than the original design, this improvement does not increase the original equipment Improving investment can effectively reduce the baking time and reduce the risk of pouring and cracking at the tundish nozzle, which greatly increases SEN nozzle temperature.

 

  • Fourth, continuous casting production

One cold, two heat, three rollers, four protections, five ingredients

The main function of the continuous casting process is to solidify the molten steel and form a slab of regular geometric dimensions. Influencing factors, in short: one cold, two heat, three rollers, four protections and five components. Cold refers to cooling, including secondary cooling in the primary cooling fan zone of the mold, and various cooling curves; heat refers to various temperatures, including molten steel entering station temperature, tundish, nozzle baking temperature, cooling water temperature, casting slab entering The temperature of the straightening zone, etc.; the roller refers to the general term for the accuracy of the equipment, the accuracy of the roll gap, the accuracy of the roll surface and the accuracy of the outer arc of the casting machine, etc.; the protection mainly refers to various types of protection, such as argon blowing protection, tundish covering agent, Mold powder protection, etc.; composition mainly means that the composition of the incoming molten steel must be qualified and correct. Otherwise, the substantial deviation of the composition of the steel grade will change, which will directly lead to production accidents. Put the ingredients at the end and do the first four items first, because they directly affect the internal quality and surface defects of the continuous casting slab. Later, it is necessary to reduce the nitrogen and carbon increase in the continuous casting process to produce slabs with qualified composition.

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As professional one-stop solution provider, LIAONING MINERAL & METALLURGY GROUP CO., LTD(LMM GROUP) Established in 2007, and focus on engineering research & design, production & delivery, technology transfer, installation & commissioning, construction & building, operation & management for iron, steel & metallurgical industries globally. 

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