Method for improving surface quality of high-purity pig iron block

Abstract

The invention provides a method for improving the surface quality of a high-purity pig iron block, which comprises the following steps: S1, distributing an iron-containing raw material and coke into a blast furnace from the top of the blast furnace through a rotating chute, spirally distributing the materials by the rotating chute according to a set angle, then smelting, and reducing the central ore-coke ratio and developing central airflow during smelting; s2, in the smelting process, high-pressure and high-temperature hot air is blown into the furnace through a round tuyere small sleeve on the lower portion of the blast furnace, coke is combusted, and reducing gas is provided; the blast-furnace tuyere area is reduced, and convective heat transfer of molten iron and high-temperature gas is enhanced; s3, high-purity pig iron molten iron smelted in the blast furnace is stored in a hearth area on the lower portion of the blast furnace, the hearth temperature is increased, and it is guaranteed that the molten iron temperature is larger than or equal to 1480 DEG C; and S4, molten iron in the hearth area is discharged from an iron notch at regular intervals and conveyed to a pig casting machine through a torpedo tank car and an iron receiving system for ingot casting, during ingot casting, slurry spraying is conducted on the iron casting mold through a slurry spraying system, iron block demolding is achieved, and meanwhile the slurry settling pond is cleaned in time. The surface quality of the high-purity pig iron can be effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of metal processing, and in particular to a method for improving the surface quality of a high-purity pig iron block. Background Art

[0002] High-purity pig iron is the key basic material for high-end iron castings. With the development of my country's economy, high-purity pig iron is increasingly widely used in high-end equipment manufacturing, and the requirements are becoming higher and higher. Qualified sintered ore and pelletized ore are produced by selecting ore powder, and then the sintered ore, pelletized ore and coke are sent to the blast furnace for smelting, and then the appropriate operation system is selected to smelt qualified high-purity pig iron. The liquid high-temperature molten iron smelted in the blast furnace is sent to the iron casting workshop by the molten iron tank car, and then the molten iron tank is tipped by the tipping mechanism. The molten iron flows into the cast iron machine mold through the molten iron flow trough. The cast iron machine mold filled with molten iron moves upward under the drive of the chain belt; during the transportation process, the cooling device sprays cooling water on the crusted iron block to accelerate the cooling of the iron block; the iron block falls off at the head star wheel, is drawn into the transfer site by the chute, and then transported out by the transport vehicle. When the chain belt returns, in order to facilitate the demoulding of the iron block, slurry is continuously sprayed into the cast iron machine mold while the cast iron machine is running.

[0003] In the current process, uneven water injection and incorrect water injection position design often cause the iron block to not fully solidify when it reaches the end of the cast iron machine, unreasonable and uneven slurry thickness leads to deterioration of the surface quality of the iron block, and the finished iron is scattered when tipping and broken due to the drop. Therefore, it is necessary to provide a method for improving the surface quality of high-purity pig iron blocks to effectively improve the surface quality of high-purity pig iron. Summary of the invention

[0004] According to the technical problem raised above, a method for improving the surface quality of high-purity pig iron blocks is provided.

[0005] The technical means adopted by the present invention are as follows:

[0006] A method for improving the surface quality of a high-purity pig iron block comprises the following steps:

[0007] S1. Iron-containing raw materials and coke are placed into the furnace from the top of the blast furnace through a rotating chute. The rotating chute performs spiral distribution at a set angle, and then smelting is carried out. During smelting, the central ore-coke ratio is reduced and the central airflow is developed;

[0008] S2. During the smelting process, high-pressure and high-temperature hot air is blown into the furnace through the circular tuyere sleeve at the bottom of the blast furnace to burn coke and provide reducing gas; the tuyere area of ​​the blast furnace is reduced, the wind speed and kinetic energy are increased, and the convection heat transfer between molten iron and high-temperature gas is strengthened;

[0009] S3. The high-purity molten pig iron smelted in the blast furnace is stored in the hearth area at the bottom of the blast furnace to increase the hearth temperature and ensure that the molten iron temperature is ≥1480℃;

[0010] S4. The molten iron accumulated in the hearth area of ​​the blast furnace is discharged from the iron mouth regularly and sent to the iron casting machine for ingot casting through the torpedo tank car and the iron receiving system. When casting ingots, the cast iron mold is sprayed through the spraying system to realize the demoulding of the iron block, and the mud sedimentation tank is cleaned in time.

[0011] Furthermore, in step S1, the central ore-coke ratio is reduced by 5%-10%.

[0012] Furthermore, in step S2, the blast furnace tuyere area is reduced by 3%-5%.

[0013] Furthermore, in step S4, graphite powder is used as slurry to ensure that the slurry is stirred evenly, and a graphite protective layer is formed on the surface of the iron block to prevent rust from appearing on the surface after iron oxidation.

[0014] Furthermore, in step S4, the slurry concentration is 10±2 kg / m 3 The spraying thickness is 3-8mm.

[0015] Furthermore, the iron receiving system includes a molten iron ditch connected to the cast iron machine and a molten iron buffer trough connected to the molten iron ditch, a slag-iron separation device is provided on the molten iron ditch, the torpedo tank car transports molten iron to the molten iron buffer trough, the molten iron buffer trough transports molten iron to the molten iron ditch, and the molten iron after separation of slag is transported to the cast iron machine through the slag-iron separation device.

[0016] Furthermore, an iron water diverter is provided between the iron water channel and the cast iron mold.

[0017] Furthermore, a material guide chute is provided at the tail of the cast iron machine, and the finished iron blocks slide into the finished casting pool along the material guide chute; an iron chain is provided on the outside of the material guide chute, the lower part of the iron chain is close to the material guide chute, and the upper part of the iron chain is installed on the suspension device.

[0018] Furthermore, the spraying system includes a motor, a slurry tank and a spraying pipeline, and the motor and the spraying pipeline are both connected to the slurry tank.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. The present invention can effectively improve the surface quality of high-purity pig iron and meet customer requirements.

[0021] 2. The present invention reduces the central ore-coke ratio by 5%-10% when smelting high-purity pig iron, and can develop central airflow.

[0022] 3. After the present invention reduces the blast furnace tuyere area by 3%-5%, the speed and kinetic energy of the hot air can be increased, the convective heat transfer between molten iron and high-temperature gas can be strengthened, and the active area at the bottom of the blast furnace can be expanded.

[0023] 4. The present invention ensures that the temperature of molten iron is ≥1480°C by increasing the furnace temperature, which is beneficial to the removal of harmful elements.

[0024] 5. The present invention sprays the cast iron mold during casting to ensure that the iron block can be demoulded smoothly. Graphite powder is used as slurry to ensure that the slurry is stirred evenly, and a graphite protective layer is formed on the surface of the iron block to prevent rust on the surface after iron oxidation.

[0025] 6. The present invention adds a slag-iron separation device in the iron receiving ditch, and utilizes the difference in specific gravity between molten iron and slag. The molten iron with higher specific gravity passes through the bottom of the device, and the slag with lower specific gravity remains on the top of the device, so the slag in the molten iron can be separated.

[0026] 7. The present invention provides a drainage device at the molten iron flow nozzle, which can evenly distribute the molten iron into the cast iron mold to avoid the molten iron in the mold from being overfilled and overflowing or being undersaturated.

[0027] 8. The slurry concentration of the present invention is 10±2 kg / m 3 The spraying thickness is 3-8mm, the slurry concentration is moderate, and the spraying thickness is moderate. It is strictly forbidden to be too thin or too thick to prevent damage to the mold and failure to demold due to too thinness. Too thick will cause the iron block to have a porridge phenomenon, affecting the surface quality of the high-purity pig iron block.

[0028] 9. The invention adds a catenary baffle at the tail of the iron casting machine, which can effectively reduce the impact force of the iron ore and avoid the iron ore from being broken.

[0029] Based on the above reasons, the present invention can be widely promoted in the fields of metal processing and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0031] Figure 1 Flow chart of the method of the present invention.

[0032] Figure 2 It is a structural schematic diagram of the device of the present invention.

[0033] Figure 3 It is a connection diagram of the iron casting machine, the iron receiving ditch, the molten iron buffer tank and the torpedo tank car of the present invention.

[0034] Figure 4 This is a schematic diagram of the iron-water diversion device provided in the present invention.

[0035] Figure 5 A schematic diagram of the catenary baffle provided in the present invention.

[0036] In the figure: 1. blast furnace; 2. molten iron tank; 3. iron connection system; 4. cast iron machine; 5. motor; slurry tank; 7. shotcrete pipe; 8. molten iron; 9. molten iron buffer tank; 10. slag-iron separation device; 11. molten iron ditch; 12. molten iron diversion device; 13. cast iron mold; 14. material guide chute; 15. suspension device; 16. iron chain; 17. finished ingot pool. DETAILED DESCRIPTION

[0037] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0038] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0040] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present invention. Meanwhile, it should be clear that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0041] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0042] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below their position devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0043] Example 1

[0044] The invention provides a method for improving the surface quality of a high-purity pig iron block, which can effectively improve the surface quality of the high-purity pig iron and meet the requirements of customers.

[0045] The method of the present invention specifically comprises the following steps:

[0046] S1. When blast furnace 1 is used to smelt high-purity pig iron, iron-containing raw materials and coke are distributed into the furnace from the top of blast furnace 1 through a rotating chute. The rotating chute performs spiral distribution at a set angle. The weight ratio of iron-containing raw materials and coke at each angle is the ore-coke ratio. When smelting high-purity pig iron, in order to develop central airflow, the central ore-coke ratio needs to be reduced by 5%-10% compared with normal.

[0047] S2. At the bottom of blast furnace 1, high-pressure and high-temperature hot air is blown into the furnace through a circular tuyere sleeve to burn coke and provide reducing gas. The sum of the areas of all tuyere sleeves is the tuyere area. After reducing the tuyere area of ​​blast furnace 1 by 3%-5%, the speed and kinetic energy of the hot air are greatly increased, which can enhance the convective heat transfer between molten iron and high-temperature gas and expand the active area at the bottom of blast furnace 1. The tuyere of blast furnace 1 is evenly arranged in the circumferential direction of the bottom of blast furnace 1, and the high-temperature and high-pressure hot air enters blast furnace 1 through the tuyere to burn with coke.

[0048] S3. The high-purity molten pig iron smelted in blast furnace 1 is stored in the hearth area at the lower part of blast furnace 1. By increasing the hearth temperature, the molten iron temperature is guaranteed to be ≥1480°C, which is conducive to the removal of harmful elements.

[0049] S4. The molten iron stored in the hearth area of ​​blast furnace 1 is discharged from the iron mouth regularly, and then sent to the iron casting machine 4 for ingot casting through the torpedo tank car (molten iron tank 2) and the iron receiving system 3. During the ingot casting, in order to ensure that the iron block can be smoothly demoulded, the cast iron mold is sprayed with graphite powder as slurry to ensure that the slurry is evenly stirred, and a graphite protective layer is formed on the surface of the iron block to prevent rust on the surface after iron oxidation. The slurry concentration is 10±2㎏ / m 3 , the thickness of the spraying is 3-8mm. The slurry concentration and the thickness of the spraying are moderate. It is strictly forbidden to be too thin or too thick. If it is too thin, it will damage the mold and fail to demold. If it is too thick, it will cause the iron block to boil porridge, forming vortex iron, affecting the surface quality of high-purity pig iron blocks. At the same time, the mud sedimentation tank needs to be cleaned in time. The mud used for spraying is new mud. If it contains other impurities, it will be mixed in the iron block and affect the quality of the iron block.

[0050] Example 2

[0051] Different from the embodiment 1, in this embodiment, in order to improve the surface quality of high-purity pig iron, when smelting high-purity pig iron in the blast furnace 1, it is necessary to ensure that the furnace temperature is uniform and sufficient, the molten iron temperature is ≥1480°C, the carbon content in the molten iron cannot be less than 4%, the cross section of the iron block can form a gray mouth, and a graphite carbon protective layer can be precipitated on the surface when the molten iron solidifies. At the same time, in order to facilitate the high-purity pig iron ore to be smoothly demolded from the cast iron block mold, a cast iron machine 4 spraying system is set. When the cast iron machine 4 runs to the spraying system, the spraying system continuously sprays the cast iron mold 13 below the cast iron machine 4, and forms a layer of graphite powder in the cast iron mold 13. The isolation layer can not only enable the high-purity pig iron block cast by the cast iron machine 4 to be demolded at a predetermined position to ensure the normal production of cast iron, but also form a protective film on the surface of the iron block to prevent iron oxidation. The spraying system comprises a motor 5 , a slurry tank 6 and a spraying pipeline 7 . The motor 5 and the spraying pipeline 7 are both connected to the slurry tank 6 , and the slurry is sprayed out through the spraying pipeline 7 .

[0052] The iron receiving system 3 includes an iron receiving ditch 11 connected to the cast iron machine 4 and a molten iron buffer tank 9 connected to the iron receiving ditch 11. The torpedo tank car transports the molten iron 8 to the molten iron buffer tank 9, and the molten iron buffer tank 9 transports the molten iron to the iron receiving ditch 11. A slag-iron separation device 10 (slag skimmer) is added to the iron receiving ditch 11. By utilizing the difference in specific gravity between molten iron and slag, the molten iron with higher specific gravity passes through the bottom of the device, and the slag with lower specific gravity remains on the upper part of the device, and the slag is cleaned manually regularly.

[0053] A drainage device (iron water distribution device 12) is provided at the molten iron flow nozzle to evenly distribute the molten iron into the cast iron mold 13, thereby preventing the molten iron in the cast iron mold 13 from being overfilled and overflowing or being undersaturated.

[0054] The tail of the iron casting machine 4 is provided with a guide chute 14, which plays a guiding role. The finished iron blocks slide into the finished ingot pool 17 along the guide chute 14. A plurality of iron chains 16 are arranged on the outside of the guide chute 14. The lower part of the plurality of iron chains 16 is close to the guide chute 14. The plurality of iron chains 16 are all suspended on a suspension device 15. The suspension device 15 can adjust the suspension position of the iron chains 16. The iron chains 16 cooperate with the guide chute 14 to prevent the iron blocks from splashing (when the iron blocks slide down along the guide chute 14, they hit the lower part of the iron chains 16, and the iron blocks are decelerated by the iron chains 16). The finished ingot pool 17 is used to store the finished ingots and discharge them regularly by car.

[0055] The present invention has been successfully applied to the production of high-purity pig iron in a small blast furnace, using a cast iron machine to cast high-purity pig iron blocks. Compared with the traditional method, the surface quality of the high-purity pig iron can be effectively improved to meet customer requirements.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for improving the surface quality of high-purity pig iron blocks, characterized in that: The steps include: S1, iron-containing raw materials and coke are introduced into the furnace from the top of the blast furnace (1) through a rotating chute, and the rotating chute is spirally distributed at a set angle, and then smelting is carried out. During smelting, the central ore-coke ratio is reduced and the central airflow is developed; S2. During the smelting process, high-pressure and high-temperature hot air is blown into the furnace through the circular tuyere sleeve at the bottom of the blast furnace (1) to burn the coke and provide reducing gas; the tuyere area of ​​the blast furnace (1) is reduced, the wind speed and kinetic energy are increased, and the convection heat transfer between the molten iron and the high-temperature gas is enhanced; S3, the high-purity molten pig iron smelted by the blast furnace (1) is stored in the furnace area at the bottom of the blast furnace (1), and the furnace temperature is increased to ensure that the molten iron temperature is ≥1480°C; S4. The molten iron accumulated in the hearth area of ​​the blast furnace (1) is discharged from the iron mouth regularly and sent to the iron casting machine (4) through the torpedo tank car and the iron receiving system (3) for ingot casting. During the ingot casting, the cast iron mold is sprayed with slurry through the slurry spraying system to realize the demoulding of the iron block, and the mud sedimentation tank is cleaned in time.

2. The method for improving the surface quality of high-purity pig iron blocks according to claim 1, characterized in that: In step S1, the central ore-coke ratio is reduced by 5%-10%.

3. The method for improving the surface quality of high-purity pig iron blocks according to claim 1, characterized in that: In step S2, the tuyere area of ​​the blast furnace (1) is reduced by 3%-5%.

4. The method for improving the surface quality of high-purity pig iron blocks according to claim 1, characterized in that: In the step S4, graphite powder is used as slurry to ensure that the slurry is stirred evenly, and a graphite protective layer is formed on the surface of the iron block to prevent rust from appearing on the surface after iron oxidation.

5. The method for improving the surface quality of high-purity pig iron blocks according to claim 1 or 4, characterized in that: In step S4, the slurry concentration is 10±2 kg / m 3 The spraying thickness is 3-8mm.

6. The method for improving the surface quality of high-purity pig iron blocks according to claim 1, characterized in that: The iron receiving system (3) comprises a molten iron ditch (11) connected to the iron casting machine (4) and a molten iron buffer tank (9) connected to the molten iron ditch (11); a slag-iron separation device (10) is provided on the molten iron ditch (11); the torpedo tank car transports molten iron to the molten iron buffer tank (9); the molten iron buffer tank (9) transports molten iron to the molten iron ditch (11); and the molten iron after separation of slag is transported to the iron casting machine (4) via the slag-iron separation device (10).

7. The method for improving the surface quality of high-purity pig iron blocks according to claim 6, characterized in that: An iron water diverter (12) is provided between the iron water channel (11) and the cast iron mold (13).

8. The method for improving the surface quality of high-purity pig iron blocks according to claim 1, characterized in that: A material guide chute (14) is arranged at the tail of the cast iron machine (4), and the finished iron blocks slide along the material guide chute (14) into the finished casting block pool (17); a plurality of iron chains (16) are arranged on the outer side of the material guide chute (14), the lower part of the plurality of iron chains (16) is close to the material guide chute (14), and the upper part of the plurality of iron chains (16) is installed on the suspension device (15).

9. The method for improving the surface quality of high-purity pig iron blocks according to claim 1, characterized in that: The spraying system comprises a motor (5), a slurry tank (6) and a spraying pipeline (7), and the motor (5) and the spraying pipeline (7) are both connected to the slurry tank (6).

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