Device for removing hydrogen fluoride in electroslag remelting process and using method thereof

Abstract

The invention relates to a device for removing hydrogen fluoride in an electroslag remelting process and a use method of the device. The device comprises a flue gas recovery cover, a crystallizer, a consumable mother electrode, a flue gas discharge pipeline, a purification reaction tank and limestone particle powder, the flue gas recovery cover is buckled at the top of the crystallizer, and a blanking hole is formed in one side of the flue gas recovery cover; the bottom of the consumable mother electrode is inserted into high-temperature liquid slag in the crystallizer from the center of the top of the flue gas recovery cover; a flue gas discharge pipeline is arranged on one side of the top of the flue gas recovery cover; the outer end of the flue gas discharge pipeline is connected to the bottom of the purification reaction tank; and the limestone particle powder is arranged in the purification reaction tank. According to the invention, the fluorine-containing gas can be recovered in a chemical reaction manner, and the content of the fluorine-containing gas in the field environment is reduced from 3.0-5.0 mg / m < 3 > to 0.02 mg / m < 3 > or less, so that the requirement on the concentration of the fluorine-containing gas in the atmosphere specified in the national standard is met, and the production operation environment is effectively protected.

Description

Technical Field

[0001] This invention relates to the field of electroslag remelting metallurgical technology, and in particular to an apparatus for removing hydrogen fluoride during electroslag remelting and its method of use. Background Technology

[0002] Electroslag remelting is a smelting method for producing high-quality steel. The process requires a certain amount of slag. To meet the metallurgical requirements of the electroslag process, a large amount of fluorite is added to the slag. Typically, the slag is a "30 / 70" slag, meaning it contains 70% CaF2 and 30% Al2O3. At high temperatures, the slag will release a certain amount of hydrogen fluoride gas.

[0003] Air sampling at an electroslag remelting production site using Panax notoginseng slag revealed extremely high concentrations of hydrogen fluoride, reaching up to 3.5 mg / m³. 3 GB3095-1996 stipulates that the concentration of fluorine-containing gases in the atmosphere must be lower than 0.02 mg / m³. 3 Hydrogen fluoride is a toxic gas that, when inhaled, irritates the respiratory mucosa, causing symptoms such as coughing, wheezing, and chest tightness. In severe cases, it can lead to bronchitis, pneumonia, or even pulmonary edema, threatening life.

[0004] To prevent pollution, people have conducted extensive research on fluorine-free electroslag materials. Although various fluorine-free slags have been developed, they are not suitable for producing high-quality electroslag steel because their viscosity is much higher than that of fluorine-containing slags and their ability to remove inclusions is relatively weak. Therefore, fluorine-free slags have not been widely used in industry.

[0005] To address this issue, patent application number 202211664897.9 proposes a "device and method for reducing fluorine-containing gaseous pollutants emitted from electroslag remelting," characterized by collecting the toxic gas hydrogen fluoride using a recovery device, then absorbing it through an alkaline aqueous solution of Ca(OH)₂, and reacting to convert it into CaF₂—a wet recovery method. While this method can recover hydrogen fluoride, some of the collected hydrogen fluoride gas escapes from the alkaline solution before being absorbed and converted, resulting in a still high concentration of hydrogen fluoride in the environment. Furthermore, the alkaline solution described in this patent is corrosive, and improper storage or use can easily lead to leaks and safety accidents. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a device and method for removing hydrogen fluoride during electroslag remelting, which recovers fluorine-containing gases through a chemical reaction, reducing the fluorine-containing gas concentration in the environment from 3.0-5.0 mg / m³. 3 Reduced to 0.02 mg / m³ 3The following measures are taken to meet the concentration requirements of fluorine-containing gases in the atmosphere as stipulated in national standards, thereby achieving effective protection of the production and operation environment.

[0007] The technical solution adopted in this invention is as follows: The present invention discloses an apparatus for removing hydrogen fluoride during electroslag remelting, comprising a flue gas recovery hood, a crystallizer, a consumable electrode, a flue gas discharge pipe, a purification reaction tank, and limestone granules. The flue gas recovery hood is fastened to the top of the crystallizer, and a feeding hole is provided on one side of the flue gas recovery hood. The bottom of the consumable electrode is inserted into the high-temperature liquid slag inside the crystallizer from the center of the top of the flue gas recovery hood. A flue gas discharge pipe is provided on one side of the top of the flue gas recovery hood. The outer end of the flue gas discharge pipe is connected to the bottom of the purification reaction tank. The limestone granules are disposed inside the purification reaction tank.

[0008] Furthermore, a gas buffer chamber is provided between the outer end of the flue gas discharge pipe and the bottom of the purification reaction tank.

[0009] Furthermore, a bottom pad is provided at the top of the gas buffer chamber; the bottom pad is a perforated plate.

[0010] Furthermore, the thickness of the base plate is 10mm-20mm, and the surface hole size is 0.5mm-1.0mm.

[0011] Furthermore, the limestone granules have a particle size of 3mm-25mm and a granule layer thickness of 50cm-100cm.

[0012] Furthermore, a heating resistance wire is provided on the inner surface of the gas buffer chamber.

[0013] Furthermore, the heating power of the heating resistance wire is 10kW-50kW.

[0014] Furthermore, a fan is installed on the flue gas exhaust pipe.

[0015] Furthermore, the inner diameter of the flue gas discharge pipe is 10cm-15cm; the inner cavity structure of the purification reaction tank is cylindrical, with an inner diameter of 1.5m-3.5m.

[0016] A method of using an apparatus for removing hydrogen fluoride during electroslag remelting, the method comprising the following steps: S1. Insert the self-consuming mother electrode into the crystallizer from the top of the flue gas collection hood, connect the discharge end of the flue gas discharge pipe to the gas buffer chamber, and start the fan to purge the bottom pad for 1-3 minutes to ensure that the bottom pad has good air permeability. S2. Turn off the fan and add limestone granules into the purification reaction tank. First, add limestone granules with a particle size of 20mm-25mm, and control the thickness of the addition to 5cm-10cm. Then, add limestone granules with a particle size of 3mm-5mm, and control the thickness of the addition to 45cm-90cm. S3. Perform electroslag remelting. After the slag in the crystallizer is completely melted, start the blower to collect the hydrogen fluoride gas generated at high temperature. In order to prevent the blower from having too much suction and causing external gas to enter the crystallizer, resulting in the loss of electroslag ingot components, the speed of the blower needs to be adjusted according to the amount of slag and the temperature. S4. During the electroslag remelting process, a certain amount of deoxidized alloy or slag is added into the crystallizer through the feeding hole on the side of the flue gas recovery hood. During the addition process, in order to prevent external gas from being drawn in, the speed of the blower is adjusted to 20r / min-50r / min. S5. In order to enable the collected hydrogen fluoride gas to react smoothly with limestone, the heating resistance wire in the gas buffer chamber is activated to heat the hydrogen fluoride gas introduced into the gas buffer chamber and control its temperature between 100℃ and 300℃. S6. At the end of the electroslag remelting production process, during the feeding stage of the electroslag ingot, the fan speed is reduced to 30r / min-50r / min. After the feeding is completed, the fan is turned off.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention can significantly reduce the concentration of harmful hydrogen fluoride gas in the air environment at electroslag remelting operation sites, from 3.0-5.0 mg / m³. 3 Reduced to 0.02 mg / m³ 3 the following; 2. This invention recovers fluorine-containing flue gas and uses limestone powder to convert hydrogen fluoride gas into calcium fluoride, enabling the recycling of some calcium fluoride. 3. Since this invention uses limestone powder to recover hydrogen fluoride, the entire recovery process does not require the use of highly alkaline solutions, making the recovery method safe and environmentally friendly. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of an apparatus for removing hydrogen fluoride during electroslag remelting proposed in this invention.

[0019] In the attached drawings, the following labels are used: 1-Flue gas collection hood; 2-Feeding hole; 3-Slag; 4-Electroslag ingot; 5-Crystallizer; 6-Consumable mother electrode; 7-Flue gas discharge pipe; 8-Fan; 9-Purification reaction tank; 10-Limestone granules; 11-Bottom plate; 12-Gas buffer chamber; 13-Heating resistance wire. Detailed Implementation

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] It should be noted that in the description of this invention, the terms "upper", "lower", "top", "bottom", "one side", "the other side", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not mean that the device or element must have a specific orientation, or be constructed and operated in a specific orientation.

[0022] See appendix Figure 1 The present invention proposes an apparatus for removing hydrogen fluoride during electroslag remelting, comprising a flue gas recovery hood 1, a crystallizer 5, a consumable mother electrode 6, a flue gas discharge pipe 7, a purification reaction tank 9, and limestone granular powder 10.

[0023] The flue gas recovery hood 1 is fastened to the top of the crystallizer 5, and a discharge hole 2 is provided on one side of the flue gas recovery hood 1. When it is necessary to add slag or alloy to the crystallizer, the discharge hole 2 is opened, and it should be closed after adding slag or alloy to prevent external gas from entering the top of the slag pool. The bottom of the consumable mother electrode 6 is inserted into the high-temperature liquid slag 3 inside the crystallizer 5 through the center of the top of the flue gas recovery hood 1; a flue gas discharge pipe 7 is provided on one side of the top of the flue gas recovery hood 1; the outer end of the flue gas discharge pipe 7 is connected to the bottom of the purification reaction tank 9; the limestone granular powder 10 is laid inside the purification reaction tank 9.

[0024] In order to facilitate the smooth discharge of flue gas from inside the crystallizer 5, a fan 8 is installed on the flue gas discharge pipe 7 in this embodiment. To ensure that the extracted flue gas flows steadily into the purification reaction tank 9 and reacts fully with the limestone granules 10 in the tank, a conical gas buffer chamber 12 is provided between the outlet end of the flue gas discharge pipe 7 and the purification reaction tank 9. To ensure that the flue gas flows evenly into the purification reaction tank 9, a bottom pad 11 is provided between the bottom of the gas buffer chamber 12 and the bottom of the purification reaction tank 9. The bottom pad 11 is a perforated plate. To ensure that the purification reaction proceeds smoothly, a heating resistance wire 13 is provided on the inner surface of the gas buffer chamber 12 to heat the extracted flue gas and ensure that its temperature is not lower than 100°C.

[0025] In this embodiment, the thickness of the base plate 11 is 10mm-20mm, and the surface aperture is 0.5mm-1.0mm; the particle size of the limestone granules 10 is 3mm-25mm, and the thickness of the granule powder layer is 50cm-100cm; the heating power of the heating resistance wire is 10kw-50kw; the inner diameter of the flue gas exhaust pipe 7 is 10cm-15cm; and the inner cavity structure of the purification reaction tank 9 is cylindrical, with an inner diameter of 1.5m-3.5m.

[0026] A method of using an apparatus for removing hydrogen fluoride during electroslag remelting includes the following steps: S1. Insert the self-consuming mother electrode 6 from the top of the flue gas collection hood 1 into the crystallizer 5, connect the discharge end of the flue gas discharge pipe 7 to the gas buffer chamber 12, and start the fan 8 to purge the bottom pad 11 for 1-3 minutes to ensure that the bottom pad 11 has good air permeability. S2. Turn off the fan 8 and add limestone granules 10 into the purification reaction tank 9. First, add limestone granules with a particle size of 20mm-25mm, and control the thickness of the addition to 5cm-10cm. Then, add limestone granules with a particle size of 3mm-5mm, and control the thickness of the addition to 45cm-90cm. S3. Perform electroslag remelting operation. After the slag 3 in the crystallizer 5 is completely melted, start the blower 8 to collect the hydrogen fluoride gas generated by the slag at high temperature. In order to prevent the blower 8 from having too much suction, causing external gas to enter the crystallizer 5 and causing the components of the electroslag ingot 4 to burn off, the speed of the blower 8 needs to be adjusted according to the amount of slag 3 and the temperature. When the amount of slag material 3 is less than 200 kg and the temperature of the liquid slag is below 1700℃, the fan speed is controlled at 100 r / min-150 r / min; When the amount of slag material 3 is less than 200 kg and the temperature of the liquid slag is higher than or equal to 1700℃, the fan speed is controlled at 80 r / min-120 r / min; When the amount of slag material 3 is greater than 200kg, for every additional 10kg, if the temperature of the liquid slag is below 1700℃, the fan speed will be increased by 15r / min-20r / min; if the temperature of the liquid slag is higher than or equal to 1700℃, the fan speed will be increased by 5r / min-10r / min. S4. During the electroslag remelting process, a certain amount of deoxidized alloy or slag is added to the crystallizer 5 through the feeding hole 2 on the side of the flue gas recovery hood 1. During the addition process, in order to prevent external gas from being drawn in, the speed of the blower is adjusted to 20r / min-50r / min. S5. In order to enable the collected hydrogen fluoride gas to react smoothly with limestone, the heating resistance wire 13 in the gas buffer chamber 12 is activated to heat the hydrogen fluoride gas introduced into the gas buffer chamber 12 and control its temperature between 100℃ and 300℃. S6. At the end of the electroslag remelting production process, the electroslag ingot 4 is fed back during the feeding stage. The fan speed is reduced to 30r / min-50r / min. After the feeding is completed, the fan 8 is turned off.

[0027] The working principle of this invention lies in the fact that limestone can slowly react with hydrogen fluoride gas at room temperature (25°C), with the chemical reaction formula: CaCO3 + 2HF = CaF2 + CO2 + H2O. This reaction is related to the system temperature and the contact area between the reactants. Increasing the temperature and the contact area between the hydrogen fluoride gas and limestone can accelerate the reaction. Based on this principle, the method of this invention is proposed. The purpose of using limestone in this invention is mainly because, compared to lime, limestone particles have better strength, ensuring better permeability between particles and allowing hydrogen fluoride gas to diffuse better between them, thereby improving the reaction process.

[0028] The following specific embodiments further illustrate the method of using the device of the present invention: Example 1 In the process of producing 316H electroslag steel ingots for nuclear power through electroslag remelting, the above-mentioned device is used to recover hydrogen fluoride gas. The specific usage method is as follows: S1. Insert the self-consuming mother electrode 6 from the top of the flue gas collection hood 1 into the crystallizer 5, connect the discharge end of the flue gas discharge pipe 7 to the gas buffer chamber 12, and start the fan 8 to blow the bottom pad for 1 minute. S2. Turn off the fan and add limestone granules 10 into the purification reaction tank 9. First, add limestone granules with a particle size of 20mm, and control the thickness at 5cm. Then, add limestone granules with a particle size of 3mm, and control the thickness at 60cm. S3. Perform electroslag remelting operation. After the slag 3 in the crystallizer 5 is completely melted, start the blower 8 to collect the hydrogen fluoride gas generated at high temperature. In order to prevent the blower 8 from having too strong a suction force, causing external gas to enter the crystallizer 5 and causing the components of the electroslag ingot 4 to burn off, the speed of the blower 8 is adjusted according to the amount of slag 3 and the temperature.

[0029] When the amount of slag material 3 is 150kg and the temperature of the liquid slag is 1650℃, the fan speed can be controlled at 120r / min; When the amount of slag material 3 is 150kg and the temperature of the liquid slag is 1750℃, the fan speed can be controlled at 100r / min. When the amount of slag material 3 is 220kg, the fan speed is controlled at 180r / min when the temperature of the liquid slag is 1600℃; when the temperature of the liquid slag is 1750℃, the fan speed is controlled at 120r / min. S4. During the electroslag remelting process, a certain amount of deoxidized alloy or slag is added to the crystallizer 5 through the feeding hole 2 on the side of the flue gas recovery hood. During the addition process, in order to prevent external gas from being drawn in, the speed of the blower is adjusted to 25 r / min. S5. In order to enable the collected hydrogen fluoride gas to react smoothly with limestone, the heating resistance wire 13 in the gas buffer chamber 12 is activated to heat the hydrogen fluoride gas introduced into the gas buffer chamber 12 and control its temperature at 150℃. S6. At the end of the electroslag remelting production process, the electroslag ingot 4 is fed back during the feeding stage. The fan speed is reduced to 35 r / min. After the feeding is completed, the fan is turned off.

[0030] Example 3 In the process of producing Invar steel ingots by electroslag remelting, the above-mentioned device is used to recover hydrogen fluoride gas. The specific usage method is as follows: S1. Insert the self-consuming mother electrode 6 from the top of the flue gas collection hood 1 into the crystallizer 5, connect the discharge end of the flue gas discharge pipe 7 to the gas buffer chamber 12, and start the fan 8 to blow the bottom pad for 2 minutes. S2. Turn off the fan and add limestone granules 10 into the purification reaction tank 9. First, add limestone granules with a particle size of 25mm, and control the thickness at 8cm. Then, add limestone granules with a particle size of 3.5mm, and control the thickness at 70cm. S3. Perform electroslag remelting operation. After the slag 3 in the crystallizer 5 is completely melted, start the blower 8 to collect the hydrogen fluoride gas generated at high temperature. In order to prevent the blower 8 from having too strong a suction force, causing external gas to enter the crystallizer 5 and causing the components of the electroslag ingot 4 to burn off, the speed of the blower 8 is adjusted according to the amount of slag 3 and the temperature.

[0031] When the amount of slag material 3 is 150kg and the temperature of the liquid slag is 1650℃, the fan speed can be controlled at 130r / min; When the amount of slag material 3 is 150kg and the temperature of the liquid slag is 1750℃, the fan speed can be controlled at 110r / min; When the amount of slag material 3 is 220kg, the fan speed is controlled at 185r / min when the temperature of the liquid slag is 1600℃; when the temperature of the liquid slag is 1750℃, the fan speed is controlled at 125r / min. S4. During the electroslag remelting process, a certain amount of deoxidized alloy or slag is added to the crystallizer 5 through the feeding hole 2 on the side of the flue gas recovery hood. During the addition process, in order to prevent external gas from being drawn in, the speed of the blower is adjusted to 30 r / min. S5. In order to enable the collected hydrogen fluoride gas to react smoothly with limestone, the heating resistance wire 13 in the gas buffer chamber 12 is activated to heat the hydrogen fluoride gas introduced into the gas buffer chamber 12 and control its temperature at 200℃. S6. At the end of the electroslag remelting production process, the electroslag ingot 4 is fed back during the feeding stage. The fan speed is reduced to 25 r / min. After the feeding is completed, the fan is turned off.

[0032] The comparison between the above embodiments and the original process is shown in the table below.

[0033]

[0034] Matters not covered in this invention are common knowledge.

[0035] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An apparatus for removing hydrogen fluoride during electroslag remelting, characterized in that: The device includes a flue gas recovery hood, a crystallizer, a consumable electrode, a flue gas discharge pipe, a purification reaction tank, and limestone granules. The flue gas recovery hood is attached to the top of the crystallizer, and a discharge hole is provided on one side of the flue gas recovery hood. The bottom of the consumable electrode is inserted into the high-temperature liquid slag inside the crystallizer from the center of the top of the flue gas recovery hood. A flue gas discharge pipe is provided on one side of the top of the flue gas recovery hood. The outer end of the flue gas discharge pipe is connected to the bottom of the purification reaction tank. The limestone granules are placed inside the purification reaction tank.

2. The apparatus for removing hydrogen fluoride during electroslag remelting according to claim 1, characterized in that: A gas buffer chamber is provided between the outer end of the flue gas discharge pipe and the bottom of the purification reaction tank.

3. The apparatus for removing hydrogen fluoride during electroslag remelting according to claim 2, characterized in that: A bottom pad is provided at the top of the gas buffer chamber; the bottom pad is a perforated plate.

4. The apparatus for removing hydrogen fluoride during electroslag remelting according to claim 3, characterized in that: The thickness of the base plate is 10mm-20mm, and the surface aperture is 0.5mm-1.0mm.

5. The apparatus for removing hydrogen fluoride during electroslag remelting according to claim 1, characterized in that: The limestone granules have a particle size of 3mm-25mm and a granule layer thickness of 50cm-100cm.

6. The apparatus for removing hydrogen fluoride during electroslag remelting according to claim 3, characterized in that: The inner surface of the gas buffer chamber is provided with a heating resistance wire.

7. The apparatus for removing hydrogen fluoride during electroslag remelting according to claim 6, characterized in that: The heating power of the heating resistance wire is 10kW-50kW.

8. The apparatus for removing hydrogen fluoride during electroslag remelting according to claim 6, characterized in that: A fan is installed on the flue gas discharge pipe.

9. The apparatus for removing hydrogen fluoride during electroslag remelting according to claim 1, characterized in that: The inner diameter of the flue gas discharge pipe is 10cm-15cm; the inner cavity structure of the purification reaction tank is cylindrical, with an inner diameter of 1.5m-3.5m.

10. The method of using the apparatus for removing hydrogen fluoride during electroslag remelting according to claim 8, characterized in that: The method includes the following steps: S1. Insert the self-consuming mother electrode into the crystallizer from the top of the flue gas collection hood, connect the discharge end of the flue gas discharge pipe to the gas buffer chamber, and start the fan to purge the bottom pad for 1-3 minutes to ensure that the bottom pad has good air permeability. S2. Turn off the fan and add limestone granules into the purification reaction tank. First, add limestone granules with a particle size of 20mm-25mm, and control the thickness of the addition to 5cm-10cm. Then, add limestone granules with a particle size of 3mm-5mm, and control the thickness of the addition to 45cm-90cm. S3. Perform electroslag remelting. After the slag in the crystallizer is completely melted, start the blower to collect the hydrogen fluoride gas generated at high temperature. In order to prevent the blower from having too much suction and causing external gas to enter the crystallizer, resulting in the loss of electroslag ingot components, the speed of the blower needs to be adjusted according to the amount of slag and the temperature. S4. During the electroslag remelting process, a certain amount of deoxidized alloy or slag is added into the crystallizer through the feeding hole on the side of the flue gas recovery hood. During the addition process, in order to prevent external gas from being drawn in, the speed of the blower is adjusted to 20r / min-50r / min. S5. In order to enable the collected hydrogen fluoride gas to react smoothly with limestone, the heating resistance wire in the gas buffer chamber is activated to heat the hydrogen fluoride gas introduced into the gas buffer chamber and control its temperature between 100℃ and 300℃. S6. At the end of the electroslag remelting production process, during the feeding stage of the electroslag ingot, the fan speed is reduced to 30r / min-50r / min. After the feeding is completed, the fan is turned off.

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