A method for baking molten iron ladle

Abstract

This invention relates to the field of steelmaking process technology, specifically a method for baking molten iron ladles. The method includes baking processes for molten iron ladles with newly poured permanent layers, molten iron ladles with repaired permanent layers and rebuilt working layers, repaired molten iron ladles, and the activation of stored ladles. This invention provides a method for baking molten iron ladles with newly poured permanent layers, repaired molten iron ladles, molten iron ladles with only the permanent layer retained and then rebuilt working layers, and the activation of stored ladles. These methods impose baking process restrictions to ensure the quality of molten iron baking, stabilize the temperature drop of molten iron, reduce the occurrence of accidents, provide qualified molten iron for the converter, and ensure stable and smooth production.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of steelmaking process, and relates to a molten iron ladle baking method. BACKGROUND

[0002] The existing molten iron ladle is divided into two types of open molten iron ladle and torpedo type molten iron ladle. The open molten iron ladle is also called molten iron ladle, and the torpedo type molten iron ladle is also called molten iron mixer. The torpedo type molten iron ladle is widely used in foreign large and medium-sized steel enterprises. The molten iron ladle used by large blast furnaces is a torpedo type.

[0003] The molten iron ladle is also called iron ladle, iron ladle, and iron ladle, which is specially designed for steelmaking furnaces, so it is divided into many types according to the capacity, but the shapes are similar. Compared with most industrial furnaces in the steelmaking plant, the structure of the molten iron ladle is relatively simple, and the lining material requirement is not high. Generally, high alumina, aluminum carbon or aluminum silicon carbide refractory materials are used. The construction sequence is: bottom permanent layer-wall permanent layer-bottom working layer-wall working layer. The construction machine is a special hydraulic lifting platform. The permanent layer of the molten iron ladle has a brick structure or is cast into a shape, and the cast into a shape is usually used. The bottom working layer and the wall working layer are generally built by bricks. The wall working layer is built by bricks in two ways, ring building and spiral building.

[0004] Generally, the molten iron ladle needs to be baked after the construction of the permanent layer and the working layer is completed. The quality of the molten iron ladle baking not only affects the service life of the molten iron ladle, but also directly affects the temperature drop of the molten iron in the use process, reduces the turnover rate of the molten iron ladle, and affects the production of the converter. The operating cost is increased. Secondly, the molten iron ladle in the use process is repaired by digging, or only the permanent layer is reserved, and then the molten iron ladle with the working layer is baked. However, the existing technology has less research on the baking direction of the molten iron ladle, which leads to low baking quality of the molten iron ladle. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a molten iron ladle baking method to ensure the baking quality of the molten iron ladle, stabilize the molten iron temperature drop, reduce the occurrence of accidents, provide qualified molten iron for the converter, and ensure the stable and smooth production.

[0006] To achieve the above purpose, the present application provides the following technical scheme:

[0007] A molten iron ladle baking method, including a new cast permanent layer molten iron ladle, a molten iron ladle with a reserved permanent layer and a newly built working layer, a molten iron ladle repaired by digging for use, and a baking process for the use of a sealed ladle;

[0008] The baking process of the new cast permanent layer molten iron ladle includes: after the new cast permanent layer molten iron ladle is demolded for one day, the new cast permanent layer is baked, the baking time is not less than 48 hours, and the outer shell temperature of the molten iron ladle is > 90-105℃ after the baking is stopped;

[0009] After the newly poured permanent layer is baked, bricks are laid to form the working layer. After the working layer is completed, it needs to be left to stand naturally before being baked online. The natural standing time is ≥1 week. The online baking time includes 12 hours of low-heat baking, 24 hours of medium-heat baking, and 24 hours of high-heat baking in sequence.

[0010] The baking process for molten iron ladles that retain the permanent layer and rebuild the working layer is as follows: direct online baking is carried out, and the online baking time includes 12 hours of low-heat baking, 24 hours of medium-heat baking, and 12 hours of high-heat baking in sequence.

[0011] The baking process for repairing used molten iron ladles: After the repair is completed, the ladle should be left to stand naturally before being baked online. The natural standing time should be ≥5 days. The online baking time includes 4 hours of medium-heat baking and 8 hours of high-heat baking.

[0012] The baking process used for the sealed storage tank is: direct online baking, and the online baking time includes 4 hours of high-temperature baking;

[0013] The qualified baking temperature standards for small, medium, and large fires are based on the temperature of the molten iron ladle shell. When baking with a small fire, the temperature of the molten iron ladle shell is controlled at 50-100℃; when baking with a medium fire, the temperature of the molten iron ladle shell is controlled at 100-180℃; and when baking with a large fire, the temperature of the molten iron ladle shell is controlled at 230℃ or higher, and the temperature of the refractory material inside the molten iron ladle reaches 400℃ or higher, and the temperature of the bottom inside the molten iron ladle is ≥500℃.

[0014] Furthermore, the baking process uses a covered iron ladle baker and mixed gas as fuel.

[0015] Furthermore, the mixed gas includes blast furnace gas, converter gas, and coke oven gas.

[0016] Furthermore, the mixed gas flow control principle is as follows: the flow rate for small fire is 400-450 m3 / h, the flow rate for medium fire is 500-550 m3 / h, and the flow rate for large fire is 550-600 m3 / h, and the pressure of the mixed gas is 8-10 kPa, so that the molten iron ladle can reach the corresponding temperature standard when it is heated by small fire, medium fire or large fire.

[0017] Furthermore, in the baking process of the molten iron ladle with the newly cast permanent layer, if the molten iron ladle is left to stand naturally for less than one week, the low-fire baking time is extended by 4 hours.

[0018] Furthermore, in the baking process of repairing used molten iron ladles, if the molten iron ladle has been left to stand naturally for less than five days, it is first baked at a low heat for 4 hours, and then baked at a medium heat.

[0019] Furthermore, in the baking process of the sealed tank, if the time from the end of the online baking to the time when the molten iron is filled into the iron ladle exceeds 6 hours, the online baking needs to be carried out again.

[0020] The beneficial effects of this invention are as follows:

[0021] This invention provides a method for baking molten iron ladles. The baking process is restricted for molten iron ladles with newly poured permanent layers, molten iron ladles that are repaired during use, molten iron ladles that only retain the permanent layer and then rebuild the working layer, and molten iron ladles that are put into use after sealing. This ensures the quality of molten iron ladle baking, stabilizes the temperature drop of molten iron, reduces the occurrence of accidents, provides qualified molten iron for converters, and ensures stable and smooth production.

[0022] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Detailed Implementation

[0023] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0024] A method for baking molten iron ladles restricts the baking process for molten iron ladles with newly poured permanent layers, molten iron ladles that have been repaired by excavation and patching, molten iron ladles that only retain the permanent layer and then rebuild (build) the working layer, and molten iron ladles that have been sealed for use.

[0025] The baking process for the newly cast permanent layer molten iron ladle includes: one day (24 hours) after the newly cast permanent layer molten iron ladle is demolded, the newly cast permanent layer is baked at a low temperature for no less than 48 hours, and the baking can be stopped when the outer shell temperature of the molten iron ladle is >90-105℃.

[0026] After the newly poured permanent layer is baked, bricks are laid to form the working layer. After the working layer is completed, it needs to be left to stand naturally before being baked online, and the natural standing time is ≥1 week.

[0027] The baking time includes 12 hours of baking at low heat, 24 hours of baking at medium heat, and 24 hours of baking at high heat, for a total of 60 hours. In special circumstances, such as when there is a shortage of molten iron ladle and the ladle has not been stored naturally for more than one week, the baking time at low heat will be extended by 4 hours, while the baking times at medium heat and high heat will remain unchanged.

[0028] The baking process for the molten iron ladle that retains the permanent layer and rebuilds the working layer is as follows: direct online baking is carried out, and the online baking time includes 12 hours of low-heat baking, 24 hours of medium-heat baking, and 12 hours of high-heat baking, for a total of 48 hours of baking.

[0029] The baking process for repairing used molten iron ladles: The repair process includes simultaneous repair of the ladle bottom and slag line, as well as repair of the slag line or ladle bottom separately. After the repair is completed, the ladle should be left to stand naturally before being baked on the line, and the natural standing time should be ≥5 days.

[0030] The baking time includes 4 hours of medium-heat baking and 8 hours of high-heat baking, for a total of 12 hours. In special circumstances where molten iron ladle is in short supply and the ladle has been stored naturally for less than 5 days, it should be baked for 4 hours with low heat first, while the medium and high heat baking times remain unchanged.

[0031] The baking process used for the sealing tank involves direct online baking, which includes 4 hours of high-temperature baking. If more than 6 hours pass between the end of online baking and the iron receiving time (the time for holding molten iron), online baking must be repeated.

[0032] Preferably, the qualified baking temperature standards for low, medium, and high heat are based on the outer shell temperature of the molten iron ladle. When baking with low heat, the outer shell temperature of the molten iron ladle is controlled at 50-100°C; when baking with medium heat, the outer shell temperature of the molten iron ladle is controlled at 100-180°C; when baking with high heat, the outer shell temperature of the molten iron ladle is controlled at 230°C or higher, and the temperature of the refractory material inside the molten iron ladle reaches 400°C or higher, and the bottom temperature inside the molten iron ladle is ≥500°C. A record of lifting the ladle is made when it is used.

[0033] All of the above baking processes use a covered iron ladle baking machine and use mixed gas as fuel, which includes blast furnace gas, converter gas and coke oven gas.

[0034] The principle for controlling the flow rate of the mixed gas is as follows: the flow rate for small fires is 400-450 m³ / h. 3 / h, medium-fired flow rate is 500-550m³ / h. 3 / h, with a high fire flow rate of 550-600 m³ / h. 3 / h, and the pressure of the mixed gas is 8-10 kPa, so that the molten iron ladle can reach the corresponding temperature standard when being heated by small, medium or large fire.

[0035] Specifically, the operating steps for molten iron ladle baking are as follows: medium check, mechanical transmission check, turning on the control box power, raising the baking lid, ignition, opening the main gas valve of the baking unit, opening the gas quick-cut valve, opening the gas regulating valve, starting the blower, adjusting the gas and airflow, lowering the baking lid, closing the airflow regulating valve, turning off the blower, closing the gas regulating valve, closing the gas block cut valve, closing the gas block cut valve, closing the main gas valve, and turning off the control box power. However, the above process is the conventional operating procedure for molten iron ladle baking in the prior art, and will not be repeated here.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method of ladle baking, characterized by: The ladle includes a new permanent layer, a permanent layer and a new working layer, a repair ladle, and a baking process for a sealed ladle; The baking process of the ladle with a new permanent layer includes: after the ladle with a new permanent layer is demoulded for one day, the new permanent layer is baked for more than 48 hours, and the baking is stopped when the temperature of the outer shell of the ladle is greater than 90-105℃; After the new permanent layer is baked, the bricks are laid to form the working layer, and the working layer is naturally placed for more than one week before being baked on line, and the baking time on line includes small fire baking for 12 hours, medium fire baking for 24 hours, and large fire baking for 24 hours; The baking process of the ladle with a new permanent layer includes: after the ladle with a new permanent layer is demoulded for one day, the new permanent layer is baked for more than 48 hours, and the baking is stopped when the temperature of the outer shell of the ladle is greater than 90-105℃; The baking process of the repair ladle includes: after the repair is completed, the ladle is naturally placed for more than five days before being baked on line, and the baking time on line includes medium fire baking for 4 hours and large fire baking for 8 hours; The baking process of the sealed ladle includes: directly baking on line, and the baking time on line includes large fire baking for 4 hours; The baking temperature of the small fire, medium fire and large fire is qualified according to the temperature of the outer shell of the ladle, the temperature of the outer shell of the ladle is controlled to be 50-100℃ when small fire baking is used, the temperature of the outer shell of the ladle is controlled to be 100-180℃ when medium fire baking is used, and the temperature of the outer shell of the ladle is controlled to be more than 230℃ when large fire baking is used, and the temperature of the refractory in the ladle is more than 400℃, and the temperature of the bottom of the ladle is more than 500℃; The ladle baking process adopts the ladle baking device to carry out the capping baking, and uses the mixed gas as the fuel; the mixed gas flow control principle is as follows: the small fire flow is 400-450 m 3 / h, the medium fire flow is 500-550 m 3 / h, the large fire flow is 550-600 m 3 / h, and the pressure of the mixed gas is 8-10 kPa, so that the ladle can reach the corresponding temperature standard when the small fire, the medium fire or the large fire baking is carried out.

2. A ladle baking method according to claim 1, characterized in that: The mixed gas includes blast furnace gas, converter gas and coke oven gas.

3. A ladle baking method as claimed in claim 1, wherein: In the baking process of the ladle with a new permanent layer, when the natural placement time of the ladle is less than one week, the small fire baking time is extended by 4 hours.

4. A ladle baking method as claimed in claim 1, wherein: In the baking process of the repair ladle, when the natural placement time of the ladle is less than five days, small fire baking is first used for 4 hours, and then medium fire baking is used.

5. A method of baking a ladle according to claim 1 wherein: In the baking process of the sealed ladle, when the time from the end of baking on line to the ladle being filled with molten iron is more than 6 hours, the baking on line needs to be restarted.