Method and device for preventing casting residues in heavy ladle from adhering to ladle in process of returning to production

Abstract

According to the method and device for preventing the casting residues in the heavy ladle from adhering to the ladle in the production returning process, molten steel with the superheat degree is introduced into the ladle containing the molten iron, stable and uniform slag-metal reaction between the casting residues and the molten iron is promoted, melt temperature reduction caused by slag layer radiation, conduction heat dissipation and slag-metal reaction heat absorption is made up, and the casting residues in the heavy ladle are prevented from adhering to the ladle. The problems of adhesion, adhesion and even solidification of slag attached to the wall of the ladle are avoided, smooth proceeding of return production of hot-state casting residual molten steel in the casting residual slag is powerfully promoted, and the treatment cost of cold solidification of the casting residual slag and environmental pollution are reduced; meanwhile, more liquid metal is provided for production by additionally adding molten steel, the steel yield is increased, the yield increase of a steel mill can be powerfully promoted, the economic benefit is improved, and clean production is promoted.

Description

Technical Field

[0001] The invention relates to the technical field of steel smelting, and in particular to a method and a device for preventing cast slag in a heavy ladle from sticking to the ladle during the production process. Background Art

[0002] In the steel metallurgical process, in order to ensure the quality of the ingot, the ladle of a 250t converter steelmaking continuous casting unit will usually have 3-5 tons of refined molten steel remaining in the ladle. In addition, there will be 3-5 tons of casting slag remaining in the ladle. The molten steel and slag remaining in the ladle are collectively referred to as casting slag.

[0003] The traditional casting slag treatment process is: pour the casting slag in the ladle into a slag basin with a grid, and transport the slag basin filled with casting slag to a special slag treatment company for unloading. After cooling, the slag lumps separated by the grid are crushed with a drop hammer, followed by iron resource recovery and comprehensive utilization of the slag.

[0004] The traditional casting slag treatment process not only wastes all the heat contained in the high-temperature casting slag, but also turns the precious high-temperature refined molten steel in the casting slag into slag steel that is difficult to handle in a cold state. The recycling path is long, the recycling cost is high, and the recycling process is detrimental to the environment and practitioners.

[0005] The mainstream technical direction for the development and utilization of casting slag resources is to directly return hot casting slag to production within the steelmaking unit. Various steel companies have carried out research, development and application along different paths.

[0006] In the development of casting slag return production technology, a steel company adopted a return production path of directly returning the casting slag to the heavy-package iron ladle. The so-called heavy-package iron ladle is to pour a portion of molten iron into the empty ladle in advance, for example, pour 30 tons of molten iron, and reserve a certain amount of melt heat and mass in the ladle in advance. The heat and mass of the 30 tons of molten iron are used to buffer the subsequent 3 to 5 times of pouring casting slag into the ladle. The temperature of the melt in the ladle is lowered and the impact on the inner lining of the ladle. However, due to the fluctuations of molten steel temperature and process cycle in various links of steelmaking, in actual operation, the casting slag temperature will still be seriously reduced or even stick to the ladle, making it difficult to pour the slag.

[0007] This is because there is usually about half an hour's interval between each two adjacent pourings of casting slag into the ladle. During this half-hour interval, the melt in the ladle is exposed. Since the density of the hot molten slag in the casting slag is lower than that of the hot molten steel and molten iron, after the casting slag is poured into the ladle, the surface of the ladle is always the casting slag layer, and its radiation and conduction cooling will be very significant. In addition, when pouring the casting slag into the ladle, the falling casting slag flow impacts the molten iron in the ladle, and the hot slag in the casting slag is usually oxidizing slag, containing a higher proportion of (FeO) components, etc. In this way, the highly oxidizing (FeO) will react with the reducing elements [C], [Si], [Mn] and the like rich in the molten iron. This reaction is an endothermic reaction. When the temperature of the casting slag layer decreases to or below about 1350°C (the approximate melting point of the hot slag in the casting slag) due to the cooling of the return gap radiation conduction and the reaction endothermic reaction, the slag viscosity will increase sharply to form a sticky bag, and even part of the slag will directly condense to form a sticky bag. Summary of the invention

[0008] The purpose of the present invention is to provide a method and device to prevent the casting slag in the heavy ladle from sticking to the ladle during the production process of the casting slag return, solve the problem of the slag sticking to the ladle wall during the production process of the casting slag return, promote the full implementation of the casting slag return production process, and have significant economic and environmental benefits.

[0009] To achieve the above object, the technical solution of the present invention is:

[0010] A method for preventing the casting slag in a heavy ladle from sticking to the ladle during the production process, comprising the following steps:

[0011] 1) After the molten iron is loaded into the ladle for standby use, the amount of molten iron loaded is 10-15% of the molten iron volume, and the ladle filled with molten iron is called a heavy ladle; the scrap steel is melted and the molten steel temperature is controlled to be ≥1550℃ to form superheated molten steel for standby use;

[0012] 2) After the molten steel is poured, the casting slag in the ladle is injected into the heavy ladle iron ladle, and before the heavy ladle iron ladle receives the casting slag again, the superheated molten steel is injected into the heavy ladle iron ladle at a single point or multiple points intermittently; the above operation is repeated until the heavy ladle iron ladle receives the casting slag;

[0013] 3) Return the heavy ladle that receives the casting slag to production for utilization.

[0014] Preferably, the injection amount of the superheated molten steel is 50-1000 kg / ton of casting slag.

[0015] Preferably, during the process of injecting the superheated molten steel into the ladle, the ladle rotates around its central axis.

[0016] Preferably, the superheated molten steel is injected into the ladle through a chute.

[0017] In the method of the present invention:

[0018] In the interval between the time when the heavy ladle takes on the casting slag and the time when it takes on the casting slag again, the molten superheated molten steel is intermittently injected into the heavy ladle in small amounts for multiple times. The injected superheated molten steel compensates the casting slag for heat, so as to prevent the casting slag from slagging due to temperature drop caused by heat dissipation.

[0019] Specifically, since the density of the injected superheated molten steel is greater than that of the upper slag layer and the lower molten iron in the ladle, the molten steel with a certain degree of superheat pouring into the ladle will promote a large-scale convection circulation movement of the melt in the ladle, increase the magnitude of the contact interface between the slag and the molten iron and continuously update it, greatly increase the contact range and frequency between the slag and the molten iron, promote the slag-metal reaction between the slag and the molten iron, and promote the diffusion movement of the slag, molten iron and slag-metal reaction products in the ladle.

[0020] Due to the accelerated transfer and diffusion of mass, heat and momentum, a stirring or dispersed distribution of the multiphase medium is caused, so that the superheated molten steel can transfer heat, mass and momentum to the casting slag and molten iron in a timely and more evenly distributed manner, compensating for the temperature drop of the casting slag caused by radiation, conduction heat dissipation and slag-metal reaction endothermicity, promoting and maintaining the free flow of the melt in the ladle, so that the slag will not stick to the wall of the ladle, reducing the repair damage of the ladle, extending the service life of the ladle, and promoting cost reduction and efficiency improvement of the steel plant.

[0021] The casting slag on the top layer in the ladle is constantly replaced, so that the heat of the superheated molten steel is promptly distributed throughout the ladle, which not only replenishes the heat consumed by the reaction between the casting slag and the molten iron, but also makes the cooling casting slag on the top layer of the ladle be constantly replaced by the hot casting slag on the lower layer. The casting slag on the top layer is full of heat, which is enough to offset the heat emitted by the casting slag when the ladle takes it again, so that the casting slag will not condense due to continuous cooling, thereby avoiding slag sticking to the ladle and ensuring the smooth return of the casting slag to production.

[0022] The present invention also discloses a device for preventing the casting slag in the heavy ladle from sticking to the ladle during the production process, which comprises:

[0023] Ladle;

[0024] A chute is arranged above the ladle, and the chute is one or more;

[0025] The rotating mechanism is arranged at the bottom of the ladle.

[0026] Furthermore, a smelting furnace is also included.

[0027] Preferably, the chute is provided with a plurality of outlets.

[0028] Preferably, a heat-insulating cover is provided on the chute.

[0029] Preferably, a dust hood is provided above the ladle.

[0030] The number of the chutes is one or more, or the chutes are provided with a single outlet or multiple outlets, so that the superheated molten steel forms multiple streams of molten steel and flows into the ladle at a single point or multiple points, so that impact stirring can be generated at multiple different places on the surface of the casting slag in the ladle, on the one hand, quickly replenishing the heat loss caused by the slag-metal reaction between the casting slag poured into the ladle and the molten iron; on the other hand, by pouring a small amount of superheated molten steel from time to time, the impact stirring generated when the superheated molten steel is injected stimulates the molten iron in the ladle to form a convection cycle, promotes the heat, momentum and mass exchange between the melts, and always keeps the surface casting slag in a liquid state, thereby avoiding the surface casting slag from not flowing for a long time and radiating heat to cause the slag to stick to the ladle, and more effectively promoting the return of the casting slag to production.

[0031] A rotating mechanism is set under the ladle, so that the landing point of the injected superheated molten steel will be dynamically updated, and the casting slag and molten iron in the heavy ladle will be fully refurbished and stirred, so that the reaction between the hot molten slag and molten iron can be completed more conveniently. The heat supply of the superheated molten steel offsets the heat absorbed by the slag-metal reaction. The temperature of the slag layer on the upper layer of the ladle is always supported by the heat of the external superheated molten steel, and the temperature does not drop below its crusting temperature, which avoids the slag layer from sticking to the ladle wall. In this way, the casting slag can be injected into the ladle multiple times without the ladle sticking, and the established casting slag return production process can be successfully completed.

[0032] A heat preservation cover is arranged above the chute to prevent the high temperature molten steel from radiating heat.

[0033] The differences and improvements of the present invention over the prior art are as follows:

[0034] Chinese patent CN2018102072178 discloses "a method for recovering molten steel by returning hot casting slag to a ladle", which receives and circulates multiple ladles of casting slag by setting up a heat preservation furnace in the molten steel receiving span. The function of the heat preservation furnace is to heat the casting slag by induction heating or oxygen blowing, and pour at least three ladles of casting slag. Since the casting slag is a poor conductor of heat, no matter whether induction heating or oxygen blowing is used for heating, the thick slag layer cannot be heated, and the slag layer on the upper surface will also cool down and solidify, which cannot play the role of heating or heat preservation of the slag.

[0035] Chinese patent CN2018115574613 discloses "a method for recycling hot casting slag in a steel ladle in a converter", step 1) after the converter taps steel, the converter slag is splashed in the converter, and the converter slag is splashed and all of it remains in the converter, located at the bottom and lining of the converter; step 2) the molten iron is desulfurized and pretreated in the molten iron tank, and the hot casting slag is mixed with the molten iron after slagging and added to the converter for converter smelting. After the molten iron is pretreated and slag is slaged, the temperature of the molten iron will be greatly reduced, and then the casting slag is directly poured into it. The further reaction of the casting slag and the molten iron will absorb heat, so the casting slag is easy to stick to the ladle, so the amount of molten iron pre-loaded in the ladle accounts for the vast majority of the volume of the molten iron ladle, so the amount of casting slag that can be taken is much less.

[0036] Chinese patent CN2010102764524 discloses "a method for recycling and reusing hot slag from continuous casting ladle". In continuous casting production, after the ladle molten steel is injected into the tundish, the molten hot slag in the ladle is poured into the heavy iron tank; then the hot slag is added to the converter together with the molten iron for steelmaking. The patent mentions that the slag may coagulate, but no solution is proposed. The present invention focuses on how to prevent the casting slag from coagulating due to continuous cooling.

[0037] Chinese patent CN2014102591190 discloses "A method for operating a hot metal ladle to recover excess slag from continuous casting". In this patent, a heavy ladle is used to receive excess slag, but the amount of molten iron in the ladle must reach 70-80% of the total amount of iron in the ladle at the beginning. However, the pre-loaded molten iron in the present invention is only about 10%, so the present invention has ample space to receive multiple furnaces of superheated molten steel to supplement heat, so the amount of superheated molten steel poured in can have a relatively large drop and impulse to form a strong stirring and turning of the shallower molten iron and the excess slag, promote the blending and mixing of the two, and facilitate heat transfer. Otherwise, a small amount of superheated molten steel and a small pouring drop cannot cause the liquid in the ladle to churn violently, and cannot transfer heat well.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1. The present invention uses a ladle pre-filled with molten iron to receive the casting slag, and then introduces superheated molten steel to promote the stable and uniform slag-metal reaction between the casting slag and the molten iron, and compensates for the reduction in the casting slag temperature caused by the radiation and conduction heat dissipation of the casting slag surface and the heat absorption of the slag-metal reaction. Even if multiple packages of casting slag are received, the casting slag can be prevented from adhering, sticking, and even solidifying on the wall of the molten iron ladle. In the prior art, in order to prevent the casting slag from sticking to the slag, slagging, and sticking to the ladle during the production process, most of the focus is on how to quickly return the casting slag to production or improve the equipment.

[0040] 2. The molten steel introduced by the present invention is returned to production together with the casting slag, providing more liquid metal for the converter, increasing steel production, and better promoting the production of casting slag. Not only the hot casting molten steel in the casting slag is directly recovered, but also the extra superheated molten steel is returned to the steelmaking process, which can strongly promote the increase of steel production, improve economic benefits, reduce the processing cost of cooling the casting slag, and promote clean production. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a schematic diagram of a device for Example 1 of the method of the present invention;

[0042] Figure 2 This is a schematic diagram of a device for Example 2 of the method of the present invention;

[0043] Figure 3 This is a schematic diagram of the device of Example 3 of the method described in the present invention. DETAILED DESCRIPTION

[0044] See also Figure 1 to Figure 3 The device for preventing the casting slag in the heavy ladle from sticking to the ladle during the production process of the present invention comprises:

[0045] Hot metal ladle 1;

[0046] A chute 2 is arranged above the ladle 1, and the chute 2 is one or more;

[0047] The rotating mechanism 4 is arranged at the bottom of the ladle 1 .

[0048] Furthermore, a smelting furnace 3 is also included.

[0049] Preferably, the chute 2 is provided with a plurality of outlets.

[0050] Preferably, a heat-insulating cover is provided on the chute 2.

[0051] Preferably, a dust removal hood 5 is provided above the ladle 1 .

[0052] Example 1

[0053] See also Figure 1 A method for preventing the casting slag in the heavy ladle from sticking to the ladle during the production process, comprising the following steps:

[0054] 1) 10% of the total capacity of the ladle is filled with molten iron for standby use. The ladle 1 filled with molten iron is called a heavy ladle; in a 2000kW melting furnace 3, the scrap steel is melted within 20 minutes, and the temperature of the molten steel is controlled at 1700°C to form superheated molten steel for standby use;

[0055] 2) After the molten steel is poured, 6 tons of casting slag remain in the ladle 100. The ladle 100 is hoisted above the iron ladle 1, and the casting slag is poured into the iron ladle 1. From the time when the casting slag is poured out to the time when the iron ladle 1 receives the casting slag again, 1 ton of superheated molten steel is injected into the iron ladle 1 at intervals, 200 kg each time, and the injection time is about 30 seconds each time, for a total of 5 times; the above operation is repeated until the heavy iron ladle receives the casting slag;

[0056] 3) Return the heavy ladle that receives the casting slag to production for utilization.

[0057] Example 2

[0058] See also Figure 2 A method for preventing the casting slag in the heavy ladle from sticking to the ladle during the production process, comprising the following steps:

[0059] 1) molten iron accounting for 12% of the total capacity of the ladle is loaded into the ladle 1 for standby use, and the ladle 1 filled with molten iron is called a heavy ladle; in the smelting furnace 3, the clean scrap steel is melted within 20 minutes, and the temperature of the molten steel is controlled at 1650° C. to form superheated molten steel for standby use;

[0060] 2) After the molten steel is poured, 5 tons of casting slag remain in the ladle 100. The ladle is hoisted above the heavy ladle iron ladle 1, and the casting slag is poured into the iron ladle 1. Before the heavy ladle iron ladle takes on the casting slag again, the superheated molten steel in the smelting furnace 3 is injected into the iron ladle 1 through the chute 2 with multiple outlets and a heat preservation cover at intervals. The interval time for molten steel injection is 5 minutes, and the single injection amount is 100 kg;

[0061] 3) Return the heavy ladle that receives the casting slag to production for utilization.

[0062] Example 3

[0063] See also Figure 3 A method for preventing the casting slag in the heavy ladle from sticking to the ladle during the production process, comprising the following steps:

[0064] 1) Fill the ladle 1 with molten iron accounting for 15% of the total capacity of the ladle and set it aside for later use. The ladle filled with molten iron is called a heavy ladle; in the smelting furnace 3, melt the clean scrap steel and control the temperature of the molten steel at 1600°C for later use;

[0065] 2) After the molten steel is poured, 10 tons of casting slag remain in the ladle 100. The ladle 100 is hoisted above the iron ladle, and the casting slag is poured into the iron ladle 1. The rotating mechanism 4 at the bottom of the iron ladle 1 is turned on to rotate the iron ladle 1 around its central axis. Before the iron ladle 1 receives the casting slag again, 1 ton of molten steel in the smelting furnace 3 is injected into the iron ladle 1 in batches, with an injection time interval of 5 to 10 minutes and a single injection amount of 200 to 333 kg.

[0066] 3) Return the heavy ladle that receives the casting slag to production for utilization.

Claims

1. A method for preventing the casting slag in the heavy ladle from sticking to the ladle during the production process, characterized in that: The steps include: 1) After the molten iron is loaded into the ladle for standby use, the amount of molten iron loaded is 10-15% of the molten iron volume, and the ladle filled with molten iron is called a heavy ladle; the scrap steel is melted and the molten steel temperature is controlled to be ≥1550℃ to form superheated molten steel for standby use; 2) After the molten steel is poured, the casting slag in the ladle is injected into the heavy ladle iron ladle, and before the heavy ladle iron ladle receives the casting slag again, the superheated molten steel is injected into the heavy ladle iron ladle at a single point or multiple points intermittently; the above operation is repeated until the heavy ladle iron ladle receives the casting slag; 3) Return the heavy ladle that receives the casting slag to production.

2. The method for preventing the casting slag in the heavy ladle from sticking to the ladle during the production process as claimed in claim 1, characterized in that: The injection amount of the superheated molten steel is 50-1000kg / ton of casting slag.

3. The method for preventing the casting slag in the heavy ladle from sticking to the ladle during the production process as claimed in claim 1, characterized in that: During the process of injecting the superheated molten steel into the ladle, the ladle rotates around its central axis.

4. The method for preventing the cast slag from sticking to the ladle during the production process of the heavy ladle iron ladle as claimed in claim 1, characterized in that: The superheated molten steel is injected into the ladle through the chute.

5. A device for preventing the casting slag in the heavy ladle from sticking to the ladle during the production process as claimed in any one of claims 1 to 4, characterized in that: include: Ladle; A chute is arranged above the ladle, and the chute is one or more; The rotating mechanism is arranged at the bottom of the ladle.

6. The device according to claim 5, characterized in that: Also includes a smelting furnace.

7. The device according to claim 5, characterized in that: The chute is provided with a plurality of outlets.

8. The device according to claim 5 or 7, characterized in that: A heat-insulating cover is provided on the chute.

9. The device according to claim 5, characterized in that: A dust removal cover is arranged above the ladle.

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