Gas protection system and method for slag skimming in metal smelting

Abstract

The present invention relates to the technical field of metal smelting, and in particular to a gas protection system and method for slag skimming in metal smelting. A first gas feeding pipe and high-pressure nozzles are provided in a smelting furnace. When an inner furnace door is opened for various operations, a high-pressure gas is ejected downwards by means of the several high-pressure nozzles; the gas may be nitrogen, argon or carbon dioxide and forms a gas curtain on the inner side of the inner furnace door of the smelting furnace that isolates the gas inside from the air outside; the gas curtain can isolate the atmospheres inside and outside the furnace, thereby preventing generated smoke and dust from escaping and thus affecting the air environment when the inner furnace door is opened; in addition, the heat in the furnace is also blocked in the smelting furnace by the gas curtain, thereby avoiding heat loss and reducing production energy consumption and production costs. The high-pressure gas ejected from the high-pressure nozzles can also improve the local gas environments in the furnace and at the furnace door, thereby reducing the oxygen content in the vicinity and thus reducing the burning loss caused by metal oxidation so as to further reduce the production costs.

Description

A gas protection system and method for slag removal process in metal smelting Technical Field

[0001] This invention relates to the field of metal smelting technology, specifically to a gas protection system and method for the slag removal process in metal smelting. Background Technology

[0002] During normal production, smelting furnaces typically involve operations such as feeding, melting, refining, slag removal, sampling, adjusting composition, and adjusting temperature. When feeding solid materials, refining, sampling, and slag removal, the furnace door needs to be opened. At this time, the smoke and hot gas inside the furnace will escape through the open furnace door, causing environmental pollution and energy loss.

[0003] Especially during slag removal, the furnace door needs to be opened, and a slag remover is used to remove the slag from the surface of the molten metal. This process generates a large amount of smoke and dust, and the heat inside the furnace dissipates to the outside along with these fumes, resulting in heat loss and increased production energy consumption and costs. Furthermore, because oxides on the surface of the molten metal are removed during slag removal, the metals entrained in the molten metal and slag will further react with oxygen and turn into oxides, causing metal loss and further increasing production costs. Therefore, we propose a gas protection system and method for the slag removal process in metal smelting. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the existing defects and provide a gas protection system and method for the slag removal process in metal smelting. When the furnace door is opened for various operations, the atmosphere inside and outside the furnace door is isolated by high-pressure gas injected at the furnace door. At the same time, the injected gas can improve the local gas environment inside the furnace and at the furnace door, reduce metal burn-off, and effectively solve the problems in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a gas protection system for slag removal in metal smelting, comprising a smelting furnace, an inner furnace door at the slag removal port of the smelting furnace, a slag removal machine on the outside of the smelting furnace, a slag removal rod on the slag removal machine for removing floating slag from the smelting furnace, a floor at the lower part of the outside of the smelting furnace, a slag hopper placed on the floor, and a gas recovery port on the upper part of the side surface of the smelting furnace; a first gas supply pipe is installed on the smelting furnace near the inner furnace door, the first gas supply pipe is connected to an external gas source, and a plurality of high-pressure nozzles are evenly arranged on the lower surface of the first gas supply pipe, the plurality of high-pressure nozzles spraying high-pressure gas downward to form an air curtain that isolates the inside and outside air on the inner side of the inner furnace door of the smelting furnace.

[0006] As a preferred embodiment of the present invention, a top plate is fixedly installed on the upper part of the outer side of the smelting furnace. The top plate is located outside the inner furnace door. A second gas pipe and a third gas pipe are sequentially arranged on the lower side of the top plate along the direction away from the first gas pipe. Both the second and third gas pipes are connected to an external gas source. A plurality of high-pressure nozzles are evenly arranged on the lower surface of the second and third gas pipes. The high-pressure nozzles of the second gas pipe are located above the slag discharge inclined plate on the smelting furnace. The high-pressure nozzles of the third gas pipe are located above the top plate near the slag remover. Both the high-pressure nozzles of the second and third gas pipes spray high-pressure gas downward to form an air curtain that isolates the internal and external air between the inner furnace door and the slag remover.

[0007] As a preferred embodiment of the present invention, guide plates are provided on both the upper and top plates of the smelting furnace, and the guide plates are arranged on both sides of each group of high-pressure nozzles.

[0008] As a preferred embodiment of the present invention, an outer furnace door is provided on the top plate. When both the outer furnace door and the inner furnace door are closed, a sealed area is formed between the outer furnace door, the inner furnace door, the top plate, and the ground. An air pump is installed on the upper surface of the top plate, and the air pump pipe passes through the lower surface of the top plate and enters the sealed area.

[0009] As a preferred embodiment of the present invention, an air source device is installed on the upper surface of the top plate, and an air inlet pipe is provided at the air outlet of the air source device. The air inlet pipe passes through the lower surface of the top plate and enters the sealing area.

[0010] As a preferred embodiment of the present invention, an oxygen sensor is provided on the extraction pipe.

[0011] As a preferred embodiment of the present invention, the outer furnace door is hinged at the end of the top plate, and a telescopic rod is installed on the inner surface of the outer furnace door. No slag remover is installed on the outside of the smelting furnace, and the slag remover rod is installed at the movable end of the telescopic rod.

[0012] As a preferred embodiment of the present invention, the fixed end of the telescopic rod is provided with an annular preheating cavity, which is connected to an external heat source.

[0013] As a preferred embodiment of the present invention, an annular deoxygenating sleeve is provided on the outside of the preheating chamber, and a deoxygenating agent is provided inside the deoxygenating sleeve.

[0014] As a preferred embodiment of the present invention, two first gas supply pipes are provided, and the high-pressure nozzles on the two first gas supply pipes are both inclined.

[0015] This invention also provides a gas protection method for the slag removal process in metal smelting, employing the aforementioned gas protection system for the slag removal process in metal smelting, comprising the following steps:

[0016] S1) Before removing slag, close the outer furnace door and turn on the air pump. The air pump will extract the air from the sealed area through the air extraction pipe to remove as much oxygen as possible from the sealed area.

[0017] S2) By using an external heat source such as a waste heat recovery system for flue gas emissions from a smelting furnace, high-temperature gas is introduced into the preheating chamber to preheat the slag-removing rod inside the telescopic rod.

[0018] S3) Turn on the gas source equipment. Nitrogen, argon or carbon dioxide gas in the gas source equipment enters the sealed area through the gas inlet pipe, fills the sealed area and further reduces the oxygen content in the sealed area.

[0019] S4) Open the first gas supply pipe and its high-pressure nozzle. The high-pressure nozzle sprays nitrogen, argon or carbon dioxide gas, which forms a downward air curtain through the guide plate to isolate the air flow inside and outside the melting furnace.

[0020] S5) Open the inner furnace door, and then control the extension and retraction of the telescopic rod. The telescopic rod will drive the preheated slag removal rod to move into the smelting furnace and remove the slag on the surface of the molten liquid from the slag removal port into the slag hopper. This process will generate a lot of smoke and dust. The smoke and dust will be blocked in the smelting furnace by the air curtain. At the same time, the heat in the furnace will also be blocked in the smelting furnace by the air curtain.

[0021] S6) After removing the slag from the smelting furnace, control the telescopic rod to retract the slag removal rod into the sealed area, then close the inner furnace door first, then close the first gas supply pipe and its high-pressure nozzle, and the smelting furnace continues to work;

[0022] S7) Based on the total amount and temperature of slag and molten liquid in the slag hopper, let it stand and cool for h. During this process, the pressure of the sealing zone is detected by a barometer set on the top plate or the outer furnace door, and the pressure of the sealing zone is kept stable and consistent with the external atmospheric pressure by drawing air with a vacuum pump or by introducing air through a gas source device.

[0023] S8) After the molten liquid in the slag hopper cools and solidifies, turn off the air pump and air source equipment, open the outer furnace door, and continue to cool the slag and the solidified metal formed by the molten liquid under the condition of external air circulation. At this time, the surface of the slag and solidified metal comes into contact with oxygen in the external air, and the surface is oxidized to form a protective layer to prevent the inside from being oxidized.

[0024] S9) After the scum and solidified metal have cooled to a certain temperature, the scum hopper is transported away by an external transfer trolley to recover the scum and solidified metal.

[0025] S10) Place the next batch of slag hoppers for slag removal on the ground, and then close the outer furnace door;

[0026] S11) When scraping the slag again, repeat steps S1)-S10).

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows: A first gas supply pipe and high-pressure nozzles are set inside the smelting furnace. When the inner furnace door is opened for various operations, high-pressure gas is sprayed downward through several high-pressure nozzles. This gas can be nitrogen, argon, or carbon dioxide, etc., forming an air curtain inside the inner furnace door that isolates the air inside and outside. The air curtain can isolate the atmosphere inside and outside the furnace, preventing the smoke and dust generated when the inner furnace door is opened from escaping and affecting the air environment. At the same time, the heat inside the furnace is also blocked by the air curtain inside the smelting furnace, avoiding heat loss and reducing production energy consumption and production costs.

[0028] The high-pressure gas ejected from the high-pressure nozzle can also improve the local gas environment inside the furnace and at the furnace door, reduce the oxygen content nearby, thereby reducing the burn-off caused by metal oxidation and further reducing production costs.

[0029] In addition, when the slag removes the slag, it passes through the air curtain and can be carried away by the high-pressure airflow, thereby shortening the cooling time of the slag and molten liquid and improving production efficiency. Attached Figure Description

[0030] Figure 1 is a structural schematic diagram of Embodiment 1 of the present invention;

[0031] Figure 2 is a schematic diagram of the high-pressure nozzle and guide plate of the present invention;

[0032] Figure 3 is a structural schematic diagram of Embodiment 2 of the present invention;

[0033] Figure 4 is a structural schematic diagram of Embodiment 3 of the present invention;

[0034] Figure 5 is an enlarged view of the structure at point A in Figure 4 of this invention;

[0035] Figure 6 is a structural schematic diagram of Embodiment 4 of the present invention;

[0036] Figure 7 is a structural schematic diagram of Embodiment 5 of the present invention.

[0037] In the diagram: 1 Smelting furnace, 2 Inner furnace door, 3 Slag remover, 4 Slag remover rod, 5 Floor, 6 Slag hopper, 7 First gas supply pipe, 8 Gas recovery port, 9 Top plate, 10 Second gas supply pipe, 11 Third gas supply pipe, 12 High-pressure nozzle, 13 Air curtain, 14 Guide plate, 15 Outer furnace door, 16 Air extraction pump, 17 Air extraction pipe, 18 Gas source equipment, 19 Air inlet pipe, 20 Telescopic rod, 21 Oxygen sensor, 22 Preheating chamber, 23 Deoxygenation sleeve. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] Example 1, please refer to Figures 1-2. The present invention provides a technical solution: a gas protection system for slag removal process in metal smelting, including a smelting furnace 1, an inner furnace door 2 provided at the slag removal port of the smelting furnace 1, a slag removal machine 3 provided on the outside of the smelting furnace 1, and a slag removal rod 4 provided on the slag removal machine 3 for removing floating slag from the smelting furnace 1. The smelting furnace 1, the inner furnace door 2, the slag removal machine 3 and the slag removal rod 4 are all commonly used equipment in the prior art.

[0040] The smelting furnace 1 is set on the floor 5, and a slag hopper 6 for placing slag is also placed on the floor 5. The smelting furnace 1 is also equipped with an inclined plate to facilitate the removal of slag into the slag hopper 6.

[0041] A gas recovery port 8 is provided on the upper side surface of the smelting furnace 1. The gas recovery port 8 is connected to an external gas recovery fan to draw gas that may accumulate at the bottom of the furnace into the gas recovery pipe, and then introduces it into the dust removal system for treatment before it is discharged in compliance with standards. This prevents the ejected gas from causing harm to the human body.

[0042] A first gas supply pipe 7 is installed on the smelting furnace 1 near the inner furnace door 2. The first gas supply pipe 7 is connected to an external gas source, which provides nitrogen, argon or carbon dioxide as a protective gas to the first gas supply pipe 7.

[0043] The lower surface of the first gas supply pipe 7 is uniformly provided with several high-temperature and high-pressure resistant nozzles 12, such as silicon carbide nozzles or ceramic nozzles. The spray coverage width of the high-pressure nozzles 12 is 10-20cm, and the spacing between adjacent high-pressure nozzles is less than the spray coverage width of the high-pressure nozzles 12, which is 5-10cm.

[0044] Several high-pressure nozzles 12 spray high-pressure gas downwards to form an air curtain 13 inside the inner furnace door 2 of the smelting furnace 1, which isolates the air from the inside and outside. To ensure the effectiveness of the air curtain 13, and to compensate for pipeline losses and nozzle resistance, the pressure of the high-pressure gas can be set in the range of 0.2–0.6 MPa.

[0045] During operation, the gas source supplies gas through a gas supply pipeline and control system, delivering it at a certain pressure to the high-pressure nozzles 12 via the first gas delivery pipe 7. The entire jet system consists of a horizontal pipe embedded in the refractory material above the furnace door, the first gas delivery pipe 7, and a row of multiple equally spaced high-pressure nozzles 12, each the same width as the furnace door. The gas is injected downwards at a certain pressure through the nozzle system, forming an air curtain 13 that isolates the flue gas and heat inside the furnace, preventing them from escaping. Simultaneously, as the gas descends, some enters the furnace, while some accumulates near the furnace door and diffuses towards the lower furnace bottom. The gas entering the furnace (nitrogen, argon, or carbon dioxide) acts as a protective gas to prevent further oxidation of the molten metal inside the furnace, while the gas at the furnace door prevents further oxidation of the hot slag just removed by the slag remover, thus preventing metal loss.

[0046] In addition, when the slag remover 4 removes the slag, it passes through the air curtain 13 and can also be carried away by the high-pressure airflow, thereby shortening the cooling time of the slag and molten liquid and improving production efficiency.

[0047] In the preferred technical solution, a top plate 9 is fixedly installed on the upper part of the outer side of the smelting furnace 1. The top plate 9 is located on the outer side of the inner furnace door 2. The top plate 9 is fixedly installed on the outer wall or mounting frame. A sliding seal is provided between the inner furnace door 2 and the top plate 9. The opening or closing of the inner furnace door 2 does not affect the sealing performance at the contact point with the top plate 9. A second gas pipe 10 and a third gas pipe 11 are sequentially arranged on the lower side of the top plate 9, away from the first gas pipe 7. Both the second and third gas pipes 10 and 11 are connected to an external gas source. Several high-pressure nozzles 12 are evenly arranged on the lower surface of the second and third gas pipes 10 and 11. The high-pressure nozzles 12 of the second gas pipe 10 are positioned above the slag discharge ramp on the smelting furnace 1, and the high-pressure nozzles 12 of the third gas pipe 11 are positioned above the top plate 9 near the slag remover 3. Both the high-pressure nozzles 12 of the second and third gas pipes 10 spray high-pressure gas downwards, forming an air curtain 13 between the inner furnace door 2 and the slag remover 3, isolating the internal and external air. Sealing plates are also installed on both sides between the top plate 9 and the floor 5, creating two sealed spaces between the three air curtains 13. This further isolates external oxygen from entering the space where the slag hopper 6 is located, preventing the slag surface and the carried molten liquid from contacting oxygen and being oxidized before solidification, thus reducing metal burn-off. Meanwhile, the three air curtains 13 can further reduce the possibility of flue gas and heat loss inside the furnace.

[0048] The distance between the air curtain 13 formed by the first gas supply pipe 7 and its high-pressure nozzle 12 and the air curtain 13 formed by the second gas supply pipe 10 and its high-pressure nozzle 12 is greater than the thickness of the inner furnace door 2, and is between 240mm and 300mm. The distance between the air curtain 13 formed by the second gas supply pipe 10 and its high-pressure nozzle 12 and the air curtain 13 formed by the third gas supply pipe 11 and its high-pressure nozzle 12 is greater than the width of the slag hopper 6, and is between 600mm and 1200mm. The specific distance can be set according to the specifications and width of the slag hopper 6 to ensure that the slag hopper 6 is placed between the two air curtains 13 to isolate external oxygen and reduce metal oxidation and burning loss.

[0049] In a further preferred technical solution, guide plates 14 are provided on both the smelting furnace 1 and the top plate 9. The guide plates 14 are located on both sides of each group of high-pressure nozzles 12. The guide plates 14 are made of commonly used refractory materials. The guide plates 14 make it easier for the high-pressure gas ejected from the high-pressure nozzles 12 to form a sealed air curtain 13, which isolates the internal and external air circulation and heat exchange.

[0050] Example 2, please refer to Figure 3. This example is largely the same as Example 1, except that the second gas pipe 10 and the third gas pipe 11 are not installed on the top plate 9, but an outer furnace door 15 is installed on the top plate 9. When both the outer furnace door 15 and the inner furnace door 2 are closed, a sealed area is formed between the outer furnace door 15, the inner furnace door 2, the top plate 9, the floor 5, and the sealing plates installed on both sides between the top plate 9 and the floor 5. The slag hopper 6 and its internal slag, molten metal, etc. are located within this sealed area.

[0051] An air pump 16 is installed on the upper surface of the top plate 9. The air pump 16 has an air extraction pipe 17 that passes through the lower surface of the top plate 9 and enters the sealing area. The air pump 16 extracts air from the sealing area through the air extraction pipe 17, reducing the oxygen content in the sealing area and thus further reducing the oxidation of the molten metal.

[0052] In a preferred embodiment, a gas source device 18 is installed on the upper surface of the top plate 9. The gas source device 18 can be a high-pressure gas cylinder filled with nitrogen, argon, or carbon dioxide gas. An inlet pipe 19 is provided at the outlet of the gas source device 18. The inlet pipe 19 passes through the lower surface of the top plate 9 and enters the sealed area. Nitrogen, argon, or carbon dioxide gas is output through the gas source device 18 and the inlet pipe 19 to fill the sealed area, further reducing the oxygen content in the sealed area.

[0053] Compared with Example 1, this example does not require the second gas supply pipe 10 and the third gas supply pipe 11 to continuously spray nitrogen, argon or carbon dioxide gas during the slag removal process. It only needs to remove the oxygen in the sealed area and maintain stable gas pressure.

[0054] In this embodiment, a through hole for the slag removal rod can be provided on the outer furnace door 15. A sliding seal is provided between the through hole and the slag removal rod to facilitate the slag removal operation while ensuring the sealing of the sealing area.

[0055] Optionally, an oxygen sensor 21 is installed on the extraction pipe 17. The oxygen sensor 21 is used to detect the oxygen content in the air passing through the extraction pipe 17 during the extraction process and transmits the oxygen content information to the controller. The controller analyzes and judges the oxygen content in the sealed area and automatically controls the switching on and off of the extraction pump 16 and the air source equipment 18, thereby improving the degree of automation.

[0056] In Examples 1 and 2, the slag remover 3 can be equipped with an intelligent slag removal system, such as the RAMON automatic slag removal system. The RAMON automatic slag removal system is a large-scale integrated system based on machine vision, intelligent sensing, a high-performance slag remover, air blowing to remove slag, and automatic control. Through its machine vision and cameras, it can achieve automated slag removal operation, with a longer observation distance and higher slag removal efficiency compared to manual observation.

[0057] Example 3, please refer to Figures 4-5. This example is largely the same as Example 2, except that: the outer furnace door 15 is hinged at the end of the top plate 9, and the outer furnace door 15 is controlled by an external cylinder assembly or other switch. The outer furnace door 15 opens when it is flipped up and closes when it is rotated down to seal against the floor 5.

[0058] A telescopic rod 20 is installed on the inner surface of the outer furnace door 15. The telescopic rod 20 can be a multi-stage servo hydraulic cylinder or a multi-stage servo pneumatic cylinder. The telescopic rod 20 is made of high-temperature alloy or carbon fiber reinforced ceramic matrix composite material and can be used to control the extension and retraction of the slag removal rod 4 and the slag removal operation. The telescopic rod 20, oxygen sensor 21, air pump 16, valves of the gas source equipment 18, and air pumps on the first gas supply pipe 7, second gas supply pipe 10, and third gas supply pipe 11 are electrically connected to the controller of the uniform smelting system. The controller can be a commonly used controller model in existing smelting furnace systems.

[0059] In this embodiment, no slag remover 3 is installed on the outside of the smelting furnace 1; instead, the slag remover rod 4 is located at the movable end of the telescopic rod 20. During slag removal, the outer furnace door 15 is closed, placing the telescopic rod 20 and the slag remover rod 4 inside. The telescopic rod 20 moves the slag remover rod 4 into the smelting furnace 1 to perform the slag removal operation. After slag removal is completed and the slag and molten metal have cooled, the telescopic rod 20 retracts the slag remover rod 4 and opens the outer furnace door 15, allowing the telescopic rod 20 and the slag remover rod 4 to move to the upper outer side, whereby the slag hopper 6 can be transferred and the slag and cooled, solidified metal can be recovered.

[0060] Optionally, the telescopic rod 20 is slidably mounted on a guide rail inside the outer furnace door 15. A drive assembly, such as a drive screw assembly or a hydraulic cylinder, is mounted on the guide rail, which can drive the telescopic rod 20 and the slag removal rod 4 to move along the width of the furnace door, thereby removing the slag in the smelting furnace 1 in sequence. This is suitable for slag removal operations in large smelting furnaces.

[0061] Optionally, when using a small smelting furnace with a narrow furnace door, multiple telescopic rods 20 and slag-removing rods 4 can be evenly installed inside the outer furnace door 15 to simultaneously remove slag from the smelting furnace 1, thereby improving slag removal efficiency. This method is suitable for smelting furnaces with a furnace opening width of less than 6000 mm.

[0062] Optionally, the fixed end of the telescopic rod 20 is provided with an annular preheating chamber 22, which is connected to an external heat source, such as the waste heat recovery system of the flue gas emission of the smelting furnace 1. The waste heat of the flue gas is used to preheat the slag removal rod 4 inside the telescopic rod 20, which can reduce the impact of the slag removal rod 4 on the temperature inside the smelting furnace 1 and reduce the carry-out and loss of molten metal.

[0063] The preheating chamber 22 is connected to the flue gas circulation pipeline installed on the outer furnace door 15. This pipeline can be a high-temperature resistant glass fiber reinforced flexible hose with a glass fiber braided outer layer and a silicone or ceramic coating inner lining. It can open and close with the outer furnace door 15 and transport high-temperature gas.

[0064] Alternatively, an annular deoxygenating sleeve 23 is provided on the outer side of the preheating chamber 22. The deoxygenating sleeve 23 contains a deoxygenating agent, which can further remove oxygen from the sealed area. The deoxygenating sleeve 23 is sleeved on the outer side of the fixed end of the telescopic rod 20, and can be removed from the telescopic rod 20 for replacement. Expired deoxygenating agents can be replaced to ensure the deoxygenation effect.

[0065] Specifically, the inner side of the deoxygenating sleeve 23 consists of two annular heat-conducting alloy cylinders. One end of each cylinder is hinged together, and the other end is fixed to the other via clips or other components, tightly fitting against the outer side of the preheating chamber 22 of the telescopic rod 20. The outer side is a highly permeable mesh surface formed of asbestos or glass wool. The deoxygenating agent can be cuprous oxide, ferrous oxide, or iron powder, etc. Iron powder is preferred because it not only accelerates the reaction at high temperatures, rapidly oxidizing to iron oxide to remove oxygen from the sealed area, but it is also economical and can reduce costs.

[0066] The fixed end of the telescopic rod 20 is located at the lower part of the inner side of the outer furnace door 15. When the sealed area is evacuated and nitrogen, argon or carbon dioxide gas is added, the bottom convection is low and there may be some oxygen that has not been extracted. Therefore, an oxygen remover is set to assist in deoxygenation, further reducing the oxygen content in the sealed area, avoiding the oxidation of the molten liquid by the oxygen remaining at the bottom when slag is removed, and further reducing metal burn-off.

[0067] This invention also provides a gas protection method for the slag removal process in metal smelting, employing the gas protection system for the slag removal process in metal smelting as described in Example 3, comprising the following steps:

[0068] S1) Before slag removal, close the outer furnace door 15 and turn on the air pump 16. The air pump 16 extracts the air from the sealed area through the air extraction pipe 17, which can remove the oxygen in the sealed area as much as possible, avoid the molten metal from contacting oxygen and oxidizing in an unsolidified state, and reduce metal burn-off.

[0069] S2) By introducing high-temperature gas into the preheating chamber 22 through an external heat source, such as the waste heat recovery system of the flue gas emission of the smelting furnace 1, the slag-removing rod 4 inside the telescopic rod 20 is preheated. This can reduce the impact of the slag-removing rod 4 on the temperature inside the smelting furnace 1, and reduce the carry-out and loss of molten metal. At the same time, it can effectively utilize the waste heat of the flue gas, which is beneficial to energy conservation and environmental protection.

[0070] While the preheating chamber 22 preheats the slag removal rod 4, it can also heat the deoxygenating agent such as iron powder in the deoxygenating sleeve 23, so that it can accelerate the reaction with oxygen at high temperature, improve the deoxygenation efficiency, and further remove oxygen in the sealing area.

[0071] S3) Open the valve on the gas source device 18. Nitrogen, argon, or carbon dioxide gas in the gas source device 18 enters the sealing zone through the inlet pipe 19, filling the sealing zone and further reducing the oxygen content in the sealing zone. At the same time, it can keep the gas pressure in the sealing zone relatively consistent with the gas pressure in the smelting furnace 1 and the external gas pressure, so as to avoid adverse effects on the molten metal carried out by the slag.

[0072] S4) Open the first gas supply pipe 7 and its high-pressure nozzle 12. The high-pressure nozzle 12 sprays nitrogen, argon, or carbon dioxide gas, forming a downward air curtain 13 through the guide plate 14, isolating the airflow between the inside and outside of the smelting furnace 1. The air curtain can isolate the atmosphere inside and outside the furnace, preventing the smoke and dust generated when the inner furnace door is opened from escaping and affecting the air environment. The high-pressure gas sprayed from the high-pressure nozzle can also improve the local gas environment inside the furnace and at the furnace door, reduce the oxygen content nearby, thereby reducing the burn-off caused by metal oxidation and further reducing production costs.

[0073] S5) Open the inner furnace door 2, then control the extension and retraction of the telescopic rod 20. The telescopic rod 20 drives the preheated slag scraper 4 to move into the smelting furnace 1, scraping the slag on the surface of the molten liquid from the scraper opening into the slag hopper 6. This process generates a large amount of smoke and dust, which is blocked by the air curtain 13 inside the smelting furnace 1. At the same time, the heat inside the furnace is also blocked by the air curtain 13 inside the smelting furnace 1, avoiding heat loss and reducing production energy consumption and production costs.

[0074] S6) After removing the slag from the smelting furnace 1, control the telescopic rod 20 to drive the slag removal rod 4 to retract into the sealed area. Then, first close the inner furnace door 2, then close the first gas supply pipe 7 and its high-pressure nozzle 12, and the smelting furnace 1 continues to work.

[0075] S7) Based on the total amount and temperature of slag and molten liquid in slag hopper 6, allow it to cool for 2-8 hours. During this process, the pressure in the sealed area is detected by a pressure gauge installed on the top plate 9 or the outer furnace door 15. The pressure gauge is electrically connected to the controller of the smelting system. The pressure in the sealed area is kept stable and consistent with the external atmospheric pressure by controlling the air pump 16 to extract air or the air source device 18 to introduce air.

[0076] (S8) After the molten metal in the slag hopper 6 cools and solidifies, the vacuum pump 16 and the gas source equipment 18 are turned off, and the outer furnace door 15 is opened. With the external air circulating, the slag and the metal formed by the solidification of the molten metal continue to cool. At this time, the surface of the slag and the solidified metal comes into contact with oxygen in the external air, and the surface is oxidized to form a protective layer, which can prevent the inside from being oxidized.

[0077] S9) After the scum and solidified metal have cooled to a certain temperature, the scum hopper 6 is transported away by an external transfer trolley, and then the scum and solidified metal are recovered.

[0078] S10) Place the next batch of slag hoppers 6 on the ground 5, and then close the outer furnace door 15.

[0079] S11) Repeat the above steps when removing the slag again.

[0080] The barometer, telescopic rod 20, oxygen sensor 21, air pump 16, valve of air source device 18, and air pumps and controllers on the first air supply pipe 7, second air supply pipe 10 and third air supply pipe 11 used in this application are all commonly used electronic components in the prior art. Their specific structure, working principle, control method and circuit connection are all known technologies and will not be described in detail here.

[0081] Example 4, please refer to Figure 6. This example is largely the same as Examples 1, 2, and 3, except that: two first air supply pipes 7 are provided, and the high-pressure nozzles 12 on both first air supply pipes 7 are inclined at an angle of 15-45°. Both sets of high-pressure nozzles 12 are inclined towards each other. Two rows of nozzles are symmetrically distributed, spraying obliquely towards the center line. The airflow on both sides collides at the center to form a high-pressure zone, which can enhance the sealing of the air curtain 13.

[0082] Example 5, as shown in Figure 7, is largely the same as Example 4, except that the high-pressure nozzles 12 on the two first gas supply pipes 7 are staggered, which reduces the gaps between airflows and increases the uniformity of the air curtain 13 coverage. Aligned high-pressure nozzles 12 may have areas not covered by the airflow; the staggered arrangement fills these gaps, forming a more continuous air curtain. Furthermore, the staggered arrangement may change the angle and position of the airflow collision, allowing the airflows to interact at more points, forming more complex turbulence, thereby enhancing the blocking effect. The staggered arrangement also makes the pressure distribution more uniform, reducing local high-pressure or low-pressure areas, thus improving the overall stability of the air curtain. Especially when the furnace door is first opened, there is external airflow interference; the air curtain 13 formed by the staggered high-pressure nozzles 12 can more effectively resist this interference.

[0083] All parts not disclosed in this invention are prior art, and their specific structures, materials, and working principles will not be described in detail. Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A gas protection system for slag removal in metal smelting, comprising a smelting furnace (1), wherein an inner furnace door (2) is provided at the slag removal port of the smelting furnace (1), characterized in that: The smelting furnace (1) is set on the ground (5), and a slag hopper (6) is placed on the ground (5). A gas recovery port (8) is opened on the upper side surface of the smelting furnace (1). A first gas supply pipe (7) is installed on the smelting furnace (1) near the inner furnace door (2). The first gas supply pipe (7) is connected to an external gas source, and several high-pressure nozzles (12) are evenly arranged on the lower surface of the first gas supply pipe (7). The several high-pressure nozzles (12) spray high-pressure gas downwards to form an air curtain (13) that isolates the air inside and outside the inner furnace door (2) of the smelting furnace (1). A top plate (9) is fixedly installed on the upper part of the outer side of the smelting furnace (1). The top plate (9) is set on the outer side of the inner furnace door (2). An outer furnace door (15) is set on the top plate (9). When both the outer furnace door (15) and the inner furnace door (2) are closed, the outer furnace door (15), the inner furnace door (2), and the top plate are closed. (9) and the floor (5) form a sealed area; the outer furnace door (15) is hinged at the end of the top plate (9), and a telescopic rod (20) is installed on the inner surface of the outer furnace door (15). There is no slag remover (3) on the outside of the smelting furnace (1). The slag remover (4) is set at the movable end of the telescopic rod (20). The fixed end of the telescopic rod (20) is provided with an annular preheating chamber (22). The fixed end of the telescopic rod (20) is set at the lower part of the inner side of the outer furnace door (15). An annular deoxygenating sleeve (23) is provided on the outside of the preheating chamber (22). The deoxygenating sleeve (23) is provided with a deoxygenating agent. High temperature gas is introduced into the preheating chamber (22) to preheat the slag remover (4) in the telescopic rod (20). The preheating chamber (22) preheats the slag remover (4) while heating the deoxygenating agent in the deoxygenating sleeve (23). An air pump (16) is installed on the upper surface of the top plate (9). The air extraction pipe (17) on the air pump (16) passes through the lower surface of the top plate (9) and enters the sealing area. The air pump (16) extracts the air from the sealing area through the air extraction pipe (17). A gas source device (18) is installed on the upper surface of the top plate (9). An air inlet pipe (19) is provided at the outlet of the gas source device (18). The air inlet pipe (19) passes through the lower surface of the top plate (9) and enters the sealing area. Nitrogen, argon or carbon dioxide gas in the gas source device (18) enters the sealing area through the air inlet pipe (19).

2. The gas protection system for slag removal process in metal smelting according to claim 1, characterized in that: The smelting furnace (1) and the top plate (9) are both equipped with guide plates (14), which are set on both sides of each group of high-pressure nozzles (12).

3. A gas protection system for slag removal in metal smelting according to claim 2, characterized in that: An oxygen sensor (21) is installed on the extraction pipe (17).

4. A gas protection system for slag removal in metal smelting according to claim 3, characterized in that: The preheating chamber (22) is connected to an external heat source.

5. A gas protection system for slag removal in metal smelting according to any one of claims 1-4, characterized in that: There are two first gas supply pipes (7), and the high-pressure nozzles (12) on the two first gas supply pipes (7) are inclined.

6. A gas protection method for slag removal in metal smelting, characterized in that: The gas protection system for the slag removal process in metal smelting as described in claim 4 includes the following steps: S1) Before removing slag, close the outer furnace door (15) and turn on the air pump (16). The air pump (16) extracts the air from the sealed area through the air extraction pipe (17) to remove as much oxygen as possible from the sealed area. S2) High-temperature gas is introduced into the preheating chamber (22) through an external heat source to preheat the slag removal rod (4) inside the telescopic rod (20); S3) Turn on the gas source device (18). Nitrogen, argon or carbon dioxide gas in the gas source device (18) enters the sealing area through the inlet pipe (19), fills the sealing area and further reduces the oxygen content in the sealing area. S4) Open the first gas supply pipe (7) and its high-pressure nozzle (12). The high-pressure nozzle (12) sprays out nitrogen, argon or carbon dioxide gas, which forms a downward air curtain (13) through the guide plate (14) to isolate the air flow inside and outside the smelting furnace (1). S5) Open the inner furnace door (2), and then control the extension and retraction of the telescopic rod (20). The telescopic rod (20) drives the preheated slag removal rod (4) to move into the smelting furnace (1) and remove the slag on the surface of the molten liquid from the slag removal port into the slag hopper (6). This process will generate a large amount of smoke and dust. The smoke and dust are blocked in the smelting furnace (1) by the air curtain (13). At the same time, the heat in the furnace is also blocked in the smelting furnace (1) by the air curtain (13). S6) After removing the slag from the smelting furnace (1), control the telescopic rod (20) to drive the slag removal rod (4) to retract into the sealed area, then close the inner furnace door (2) first, then close the first gas supply pipe (7) and its high-pressure nozzle (12), and the smelting furnace (1) continues to work; S7) According to the total amount and temperature of slag and molten liquid in the slag hopper (6), let it stand and cool for 2-8 hours. During this process, the pressure of the sealing area is detected by the pressure gauge set on the top plate (9) or the outer furnace door (15), and the pressure of the sealing area is kept stable and consistent with the external atmospheric pressure by drawing air through the air pump (16) or drawing air through the air source equipment (18). S8) After the molten liquid in the slag hopper (6) is cooled and solidified, the air pump (16) and the gas source equipment (18) are turned off, and the outer furnace door (15) is opened. Under the condition of external air circulation, the slag and the metal formed by the solidification of the molten liquid continue to be cooled. At this time, the surface of the slag and the solidified metal comes into contact with the oxygen in the external air, and the surface is oxidized to form a protective layer to prevent the inside from being oxidized. S9) After the scum and solidified metal are cooled to a certain temperature, the scum hopper (6) is transported away by an external transfer cart to recover the scum and solidified metal; S10) Place the next batch of slag hoppers (6) on the floor (5), and then close the outer furnace door (15). S11) When scraping the slag again, repeat steps S1)-S10).

Images