An apparatus and method for reducing emissions of fluorine-containing gas pollutants from electroslag remelting

Abstract

The application discloses a device for reducing fluorine-containing gas pollutant emission in electroslag remelting and a use method, which comprises a flue gas recovery cover (1), a flue gas discharge pipeline (7) and a purification tank (10). The flue gas recovery cover (1) is respectively provided with a remelted slag discharging hole (2), a self-consuming mother electrode (6) passing hole and a flue gas discharge pipeline (7) mounting hole. The flue gas discharge pipeline (7) is arranged through the flue gas discharge pipeline (7) mounting hole, one end of the flue gas discharge pipeline (7) is located in a closed space formed by the flue gas recovery cover (1) and a crystallizer (5), and the other end is inserted into the purification tank (10). A fan (8) is arranged on the flue gas discharge pipeline (7). Through the device, the fluorine-containing flue gas is recovered, and the fluorine-containing flue gas is converted into calcium fluoride by using an alkali solution. The device can realize the cyclic and repeated use of part of the calcium fluoride, greatly reduces the concentration of fluorine-containing harmful gas in the air environment of an electroslag remelting operation site, and makes the concentration of the fluorine-containing harmful gas reduce from the original 5.6 mg / m 3 to 0.02 mg / m 3 .

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of metallurgical electroslag remelting, and particularly relates to a device for reducing emission of fluorine-containing gas pollutants in electroslag remelting and a use method. BACKGROUND

[0002] As a new special metallurgical technology, electroslag remelting plays an important role in the special steel industry. The basic principle is that the metal or alloy is re-melted into metal droplets by the resistance heat generated when the electric current passes through the molten slag in the water-cooled crystallizer, and the metal droplets are fully contacted with the liquid slag during the dropping process to achieve the purpose of purification. In order to achieve the best electroslag remelting purification effect, the electroslag remelting usually uses a "three-seven" binary slag, that is, containing 70% CaF2 and 30% Al2O3. At high temperatures, CaF2 can generate toxic gases SiF4 and HF with the components in the slag and the moisture in the air, causing environmental pollution. Related studies have shown that air sampling was conducted at the production site of electroslag remelting using a three-seven slag, and it was found that the concentrations of SiF4 and HF in the air were very high, and the highest concentration could reach 5.6 mg / m 3 , and the concentration of fluorine-containing gas in the atmosphere should be less than 0.02 mg / m 3 according to GB3095-1996. In order to prevent pollution, a large amount of research has been conducted on fluoride-free electroslag slag, and although various fluoride-free slags have been developed, due to the fact that the viscosity of fluoride-free slag is much larger than that of fluoride-containing slag, the ability to remove inclusions is relatively weak, and it is not suitable for high-quality electroslag steel production, so fluoride-free slag has not been widely used in industry. SUMMARY

[0003] The purpose of the present application is to provide a device for reducing emission of fluorine-containing gas pollutants in electroslag remelting and a use method, which realizes the recovery of fluorine-containing harmful gases generated in the electroslag remelting process, reduces the emission of fluorine-containing gases, and thus effectively protects the production working environment.

[0004] In order to achieve the purpose of the present application, a device for reducing emission of fluorine-containing gas pollutants in electroslag remelting includes a flue gas recovery hood, a flue gas discharge pipeline, and a purification tank. A remelted slag discharge hole, a consumable electrode passing hole, and a flue gas discharge pipeline mounting hole are respectively arranged on the flue gas recovery hood. A flue gas discharge pipeline is arranged through the flue gas discharge pipeline mounting hole, one end of the flue gas discharge pipeline is located in the closed space of the flue gas recovery hood and the crystallizer, and the other end is inserted into the purification tank. A fan is arranged on the flue gas discharge pipeline.

[0005] Further, a honeycomb nozzle is arranged at the discharge end of the flue gas discharge pipeline.

[0006] A use method of a device for reducing emission of fluorine-containing gas pollutants in electroslag remelting includes the following contents:

[0007] S1: fitting the fume recovery cover on the consumable electrode, and inserting the discharge end of the fume discharge pipeline into the purification tank;

[0008] S2: injecting the alkaline aqueous solution into the purification tank;

[0009] S3: starting the fan to recover the fluorine-containing gas generated at high temperature of the slag;

[0010] S4: supplementing the slag material into the crystallizer through the discharging hole of the fume recovery cover, and synchronously supplementing the alkaline aqueous solution (11) into the purification tank during the supplementing of the slag material;

[0011] S5: during the supplementing stage, the rotating speed of the fan is reduced to 60-100 r / min, and after the supplementing is completed, the fan is turned off;

[0012] S6: placing the turbid solution in the purification tank for more than 5 hours, filtering and drying the precipitate.

[0013] Further, the alkaline aqueous solution is Ca(OH)2aqueous solution, the concentration thereof is 5-10 mol / L, the added amount is matched with the amount of the remelted slag, and 10-20 L of the alkaline solution is added per kilogram of the slag material.

[0014] Further, the depth of the discharge end of the fume discharge pipeline inserted into the purification tank is controlled to be 1.5-3.0 m from the liquid surface of the alkaline aqueous solution.

[0015] Further, in order to prevent the suction of the fan from being too large to cause the external gas to enter into the crystallizer (5) and cause the composition loss of the electroslag ingot, the rotating speed of the fan is adjusted according to the amount and temperature of the slag:

[0016] when the amount of the slag is less than or equal to 100 kg and the temperature of the liquid slag is lower than 1600℃, the rotating speed of the fan is controlled to be 150-200 r / min;

[0017] when the amount of the slag is less than or equal to 100 kg and the temperature of the liquid slag is higher than and includes 1600℃, the rotating speed of the fan is controlled to be 180-240 r / min;

[0018] when the amount of the slag is greater than 100 kg, the rotating speed of the fan is increased by 5-10 r / min for each increase of 10 kg of the liquid slag at a temperature lower than 1600℃;

[0019] when the amount of the slag is greater than 100 kg, the rotating speed of the fan is increased by 8-15 r / min for each increase of 10 kg of the liquid slag at a temperature higher than and including 1600℃.

[0020] Further, when the slag material in the crystallizer is completely melted, the fan is started.

[0021] Further, the supplementing amount of the alkaline water solution is controlled to be 10-20L per kg of the slag, and the alkaline water solution is Ca(OH)2 water solution with a concentration of 5-10mol / L.

[0022] Further, the turbid solution in the purification tank is placed for 5-10 hours.

[0023] Compared with the prior art, the beneficial effects of the present application are:

[0024] (1) The concentration of fluorine-containing harmful gas in the air environment of the electric slag remelting operation site can be greatly reduced, and the concentration is reduced from the original 5.6mg / m 3 3

[0025] (2) By recycling the fluorine-containing flue gas, the fluorine-containing flue gas is converted into calcium fluoride by using an alkaline solution, and partial recycling and reuse of calcium fluoride can be achieved. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a structural schematic view of the device for reducing fluorine-containing gas pollutants discharged by the electric slag remelting of the present application.

[0027] In the figure: 1-flue gas recovery cover; 2-discharging hole; 3-liquid slag; 4-electric slag ingot; 5-crystallizer; 6-self-consuming mother electrode; 7-flue gas discharge pipeline; 8-fan; 9-honeycomb nozzle; 10-purification tank; 11-alkaline solution. DETAILED DESCRIPTION

[0028] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The described embodiments are only part of the embodiments of the present application, not all the embodiments. The description of at least one exemplary embodiment is actually only illustrative, and is by no means any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0029] The present application designs a device capable of recycling fluorine-containing harmful gas generated in the electric slag remelting process, and the specific scheme is as follows:

[0030] For example, Figure 1 ​​As shown, the present application designs a device capable of recycling the fluorine-containing harmful gas generated in the electroslag remelting process, which comprises a flue gas recovery cover 1, a flue gas discharge pipeline 7 and a purification tank 10. The flue gas recovery cover 1 is sleeved with the crystallizer 5, and a discharging hole 2 is arranged on the side of the flue gas recovery cover. When it is necessary to add slag or alloy into the crystallizer, the discharging hole 2 is opened, and when the slag or alloy is added, the discharging hole 2 is closed to prevent external gas from entering the top of the slag pool. The consumable electrode 6 passes through the top of the flue gas recovery cover and is inserted into the high-temperature liquid slag 3. The top of the flue gas recovery cover is provided with a flue gas discharge pipeline 7 mounting hole. Through the mounting hole, one end of the flue gas discharge pipeline 7 is located in the closed space of the flue gas recovery cover 1 and the crystallizer 5, and the other end is inserted into the alkaline aqueous solution 11 of the purification tank 10. In order to smoothly discharge the flue gas, a fan 8 is arranged on the pipeline. In order to disperse the collected fluorine-containing flue gas into the alkaline aqueous solution and make the fluorine-containing gas in the flue gas fully absorbed, a honeycomb spray head 9 is arranged at the discharge end of the pipeline.

[0031] In order to prevent the fluorine-containing harmful gas from being discharged into the working environment during the electroslag remelting process, the use method thereof is described as follows in combination with the schematic view:

[0032] S1: The flue gas recovery cover 1 is sleeved on the consumable electrode 6, and the honeycomb spray head at the discharge end of the flue gas discharge pipeline 7 is inserted into the purification tank 10;

[0033] S2: The alkaline aqueous solution 11 is injected into the purification tank 10. The alkaline aqueous solution is Ca(OH)2 aqueous solution, the concentration thereof is 5-10 mol / L, and the amount of addition is matched with the amount of remelted slag, that is, 10-20 L of alkaline aqueous solution is added per kilogram of slag. The depth of the honeycomb spray head at the discharge end of the flue gas discharge pipeline 7 inserted into the purification tank 10 is controlled to be 1.5-3.0 m from the surface of the alkaline aqueous solution.

[0034] S3: The electroslag remelting work is carried out. When the slag 3 in the crystallizer 5 is completely melted, the fan 8 is started to recycle the fluorine-containing gas generated at high temperature of the slag 3. In order to prevent the suction of the fan 8 from being too large, causing external gas to enter the crystallizer 5 and causing the composition of the electroslag ingot 4 to be burned, the speed of the fan 8 is adjusted according to the amount and temperature of the slag 3.

[0035] When the amount of the slag 3 is less than or equal to 100 kg and the temperature of the liquid slag is lower than 1600℃, the speed of the fan is controlled to be 150-200 r / min;

[0036] When the amount of the slag 3 is less than or equal to 100 kg and the temperature of the liquid slag is higher than and includes 1600℃, the speed of the fan is controlled to be 180-240 r / min;

[0037] When the slag amount of the slag 3 is greater than 100 kg, the fan speed is controlled to increase by 5-10 r / min for every 10 kg increase, when the temperature of the liquid slag is lower than 1600℃;

[0038] When the slag amount of the slag 3 is greater than 100 kg, the fan speed is controlled to increase by 8-15 r / min for every 10 kg increase, when the temperature of the liquid slag is higher than and including 1600℃;

[0039] S4: The slag material is consumed in the production process, and the slag material is added to the crystallizer 5 through the discharging hole 2 at the side of the flue gas recovery cover. In the process of adding the slag material, the alkali solution 11 needs to be added to the purification tank 10 at the same time, and the addition amount is controlled according to the step S2, that is, the addition amount is controlled to be 10-20 L of the alkaline aqueous solution per kg of the slag material;

[0040] S5: In the final stage of the electroslag production, the fan speed is reduced to 60-100 r / min in the feeding stage of the electroslag ingot 4, and after the feeding is completed, the fan is turned off;

[0041] S6: After the turbid solution in the purification tank 10 is placed for 5-10 hours, the precipitate is filtered out and dried, and is used to prepare the slag material, so as to realize the recycling of calcium fluoride.

[0042] Example 1

[0043] In the process of producing heat-resistant high-alloy steel electroslag ingot by electroslag remelting, the specific process for recovering the fluorine-containing gas pollutants is as follows:

[0044] S1: The flue gas recovery cover 1 is sleeved on the consumable electrode 6, and the honeycomb nozzle 9 at the discharge end of the flue gas discharge pipeline 7 is inserted into the purification tank 10;

[0045] S2: The alkaline aqueous solution 11 is injected into the purification tank 10, the alkaline solution is Ca(OH)2 aqueous solution, the concentration is 8.5 mol / L, 15 L of the alkali solution corresponds to every kg of the slag material, and the depth of the honeycomb nozzle at the discharge end of the flue gas discharge pipeline 7 inserted into the purification tank 10 is controlled to be 2.5 m from the surface of the alkaline aqueous solution;

[0046] S3: The electroslag remelting operation is performed, the fan 8 is started to recover the fluorine-containing gas generated at high temperature of the slag 3 after the slag 3 in the crystallizer 5 is completely melted, in order to prevent the suction of the fan 8 from being too large, so that the external gas enters the crystallizer 5, causing the composition of the electroslag ingot 4 to be burned, and the speed of the fan 8 is adjusted according to the amount and temperature of the slag 3.

[0047] When the slag amount of the slag 3 is less than or equal to 100 kg and the temperature of the liquid slag is lower than 1600℃, the fan speed is controlled to be 160 r / min;

[0048] When the slag amount of the slag 3 is less than or equal to 100 kg and the temperature of the liquid slag is higher than and includes 1600℃, the fan speed is controlled at 200 r / min;

[0049] When the slag amount of the slag 3 is greater than 100 kg by every increase of 10 kg, the temperature of the liquid slag is lower than 1600℃, and the fan speed is controlled at 6 r / min for speed-up control;

[0050] When the slag amount of the slag 3 is greater than 100 kg by every increase of 10 kg, the temperature of the liquid slag is higher than and includes 1600℃, and the fan speed is controlled at 10 r / min for speed-up control;

[0051] S4: The slag material is added into the crystallizer 5 through the discharging hole 2 of the side of the flue gas recovery cover, and in the process of adding the slag material, the alkali solution 11 needs to be added into the purification tank 10 synchronously, and the adding amount is controlled according to the step S2, that is, 15 L of the alkali solution corresponds to every kg of the slag material;

[0052] S5: In the final stage of the electroslag production, the fan speed is reduced to 70 r / min in the feeding stage of the electroslag ingot 4, and after the feeding is completed, the fan is closed;

[0053] S6: After the turbid solution in the purification tank 10 is placed for 8 hours, the precipitate is filtered out and dried, and is used for preparing the slag material, so that the calcium fluoride is recycled.

[0054] Example 2

[0055] In the process of producing the high-carbon steel electroslag ingot by the electroslag remelting, the specific process method for recovering the fluorine-containing gas pollutants is as follows:

[0056] S1: The flue gas recovery cover 1 is sleeved on the consumable electrode 6, and the honeycomb nozzle 9 at the discharge end of the flue gas discharge pipeline 7 is inserted into the purification tank 10;

[0057] S2: The alkali aqueous solution 11 is injected into the purification tank 10, the alkali aqueous solution is Ca(OH)2aqueous solution, the concentration is 6.5 mol / L, 12 L of the alkali solution corresponds to every kg of the slag material, and the depth of the inserted liquid surface is controlled at 2.0 m;

[0058] S3: The electroslag remelting operation is performed, when the slag material 3 in the crystallizer 5 is completely melted, the fan 8 is started to recover the fluorine-containing gas generated at high temperature of the slag 3, in order to prevent the suction of the fan 8 from being too large, so that the external gas enters into the crystallizer 5, and the composition of the electroslag ingot 4 is burned, the speed of the fan 8 is adjusted according to the amount and the temperature of the slag 3.

[0059] When the slag amount of the slag 3 is less than or equal to 100 kg and the temperature of the liquid slag is lower than 1600℃, the fan speed is controlled at 140 r / min;

[0060] When the slag amount of the slag 3 is less than or equal to 100 kg and the temperature of the liquid slag is higher than and includes 1600℃, the fan speed is controlled at 180 r / min;

[0061] When the slag amount of the slag 3 is greater than 100 kg per 10 kg increase, the temperature of the liquid slag is lower than 1600℃, and the fan speed is controlled at 5 r / min for speed-up control;

[0062] When the slag amount of the slag 3 is greater than 100 kg per 10 kg increase, the temperature of the liquid slag is higher than and includes 1600℃, and the fan speed is controlled at 8 r / min for speed-up control;

[0063] S4: The slag material is added to the crystallizer 5 through the discharge hole 2 at the side of the flue gas recovery cover. During the addition of the slag material, the alkali solution 11 needs to be added to the purification tank 10 at the same time, and the addition amount is controlled according to the description in step S2, that is, 12 L of the alkali solution corresponds to 1 kg of the slag material;

[0064] S5: At the end of the electroslag production, the fan speed is reduced to 60 r / min during the feeding stage of the electroslag ingot 4, and after the feeding is completed, the fan is turned off;

[0065] S6: After the turbid solution in the purification tank 10 is placed for 6 hours, the precipitate is filtered out and dried, and is used for preparing the slag material, so as to realize the recycling of calcium fluoride.

[0066] The use effect comparison is as follows:

[0067] Process Electroslag remelting production site fluorine-containing gas and dust concentration, mg / m 3 ]]> Original process 4.6 Example 1 0.05 Example 2 0.02

[0068] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of reducing emissions of fluorine-containing gas pollutants from electroslag remelting characterized by, The device used includes a flue gas recovery hood (1), a flue gas discharge pipeline (7), and a purification tank (10) for storing an alkaline aqueous solution (11); the flue gas recovery hood (1) is respectively provided with a remelted slag discharging hole (2), a self-consumption electrode (6) passing hole, and a flue gas discharge pipeline (7) mounting hole; the flue gas discharge pipeline (7) is arranged through the flue gas discharge pipeline (7) mounting hole, one end of the flue gas discharge pipeline (7) is located in a closed space formed by the flue gas recovery hood (1) and a crystallizer (5), and the other end is inserted into the purification tank (10); the flue gas discharge pipeline (7) is provided with a fan (8); and the method comprises the following steps: S1: The flue gas recovery hood (1) is sleeved on the self-consumption electrode (6), and the discharge end of the flue gas discharge pipeline (7) is inserted into the purification tank (10); S2: The alkaline aqueous solution (11) is injected into the purification tank (10); S3: The fan (8) is started to recover the fluorine-containing gas generated at a high temperature of the slag (3); S4: The slag material is added to the crystallizer (5) through the discharging hole (2) of the flue gas recovery hood, and the alkaline aqueous solution (11) is added to the purification tank (10) at the same time during the slag material adding process; the alkaline aqueous solution (11) is a Ca(OH)2 aqueous solution, the added amount is matched with the amount of the remelted slag, 10-20 L of the alkaline solution is added per kilogram of the slag material; S5: During the feeding stage, the rotating speed of the fan is reduced to 60-100 r / min, and after the feeding is completed, the fan is turned off; S6: The turbid solution in the purification tank (10) is placed for more than 5 hours, the precipitate is filtered and dried.

2. The method of reducing emissions of fluorine-containing gas pollutants from electro- slag remelting of claim 1, wherein, The discharge end of the flue gas discharge pipeline (7) is provided with a honeycomb nozzle (9).

3. The method of reducing emissions of fluorine-containing gas pollutants from electro- slag remelting of claim 1, wherein, The depth of the discharge end of the flue gas discharge pipeline (7) inserted into the purification tank (10) is controlled to be 1.5-3.0 m from the surface of the alkaline aqueous solution.

4. The method of reducing emissions of fluorine-containing gas pollutants from electrowinning according to claim 1, wherein, The rotating speed of the fan (8) is adjusted according to the amount and temperature of the slag (3): When the amount of the slag (3) is less than or equal to 100 kg and the temperature of the liquid slag is lower than 1600℃, the rotating speed of the fan is controlled to be 150-200 r / min; When the amount of the slag (3) is less than or equal to 100 kg and the temperature of the liquid slag is higher than 1600℃, the rotating speed of the fan is controlled to be 180-240 r / min; When the amount of the slag (3) is greater than 100 kg, the rotating speed of the fan is increased by 5-10 r / min for every increase of 10 kg of the liquid slag when the temperature of the liquid slag is lower than 1600℃; When the amount of the slag (3) is greater than 100 kg, the rotating speed of the fan is increased by 8-15 r / min for every increase of 10 kg of the liquid slag when the temperature of the liquid slag is higher than 1600℃.

5. The method of reducing emissions of fluorine-containing gas pollutants from electrowinning according to claim 1, wherein, When the slag material in the crystallizer (5) is completely melted, the fan (8) is started.

6. The method of reducing emissions of fluorine-containing gas pollutants from electrowinning according to claim 1, wherein, The turbid solution in the purification tank (10) is placed for 5-10 hours.

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