A method and device for treating silicon smelting flue gas

Abstract

The present invention discloses a method for treating silicon smelting flue gas, comprising the following steps: a. Passing the silicon smelting flue gas into a dust removal device for dust removal treatment; b. Performing plasma oxidation on the flue gas treated by the dust removal device to oxidize NO in the flue gas into NO2; c. Feeding the flue gas obtained after the treatment in step b into an absorption device, adding an oily absorbent from the top of the absorption device, adding an alkali solution to the middle part, and introducing air from the bottom of the absorption device. The flue gas undergoes a catalytic oxidation reaction in the absorption device and is stratified to form two layers, with the upper layer being the oily absorbent and the lower layer being an aqueous solution containing nitrates and sulfates. The method for treating silicon smelting flue gas of the present invention can solve the problem of simultaneous treatment of multiple pollutants such as SiO2, SO2, and NOx in silicon smelting flue gas, and achieve the goal of respectively recycling these pollutants such as SiO2, SO2, and NOx.

Description

Technical Field

[0001] The present invention belongs to the technical field of silicon smelting, and particularly relates to a method for treating silicon smelting flue gas, and more particularly, to a device for treating silicon smelting flue gas. Background Art

[0002] In the production of industrial silicon, silica reacts in the high-temperature reaction zone of an electric furnace to produce metallic Si, and at the same time, flue gases such as SiO2, SO2, and NOx are generated and discharged outside the furnace. It is estimated that about 2300 - 2500 Nm 3 of raw gas is produced per ton of industrial silicon produced. In recent years, although the industrial silicon electric furnaces in China have been continuously improved in terms of furnace capacity, mechanization, and automation levels, there is still a considerable proportion of flue gas that is currently treated in a crude manner or even untreated and directly discharged into the atmosphere, with excessive emissions.

[0003] With the increasing emphasis on environmental protection, the purification of industrial silicon electric furnace flue gas and achieving up-to-standard emissions are imminent. It is worth noting that microsilica powder in the flue gas is an excellent and efficient industrial additive and is widely used in construction, building materials, metallurgy, and high-grade thermal insulation materials. SO2 and NOx can also be converted into high-value-added products, such as fertilizers, through sulfur and nitrate purification and resource utilization technologies.

[0004] Therefore, it is necessary to develop a method for treating silicon smelting flue gas to control the electric furnace flue gas, which can solve the problem of excessive emissions of dust-containing flue gas in industrial silicon production, and can also achieve considerable economic benefits, realizing the purpose of turning waste into treasure and comprehensive utilization. Summary of the Invention

[0005] The present invention is based on the inventor's discovery and understanding of the following facts and problems:

[0006] When smelting industrial silicon, flue gas containing multiple pollutants such as SiO2, SO2, and NOx is generated. Existing flue gas control and purification technologies have gradually expanded from single-pollutant control technologies (such as separate SO2 removal technologies, NOx removal technologies, etc.) to multi-pollutant control technologies. The most common is the integrated technology formed by integrating multiple single-pollutant control technologies, that is, the combined technology. The combined technology requires multiple sets of devices and has disadvantages such as large floor area, complex process, and high operating costs.

[0007] There are two major technical routes, namely wet and dry methods, in the related technologies.

[0008] In the wet process, water is in direct contact with the flue gas, and droplets and liquid films are used to adhere to the flue gas to achieve the purpose of dust collection and purification. It can effectively remove harmful gases with good hydrophilicity such as SO2, but has poor removal effects on harmful gases with poor hydrophilicity such as NO, and cannot effectively recover SiO2. At the same time, it has a large water consumption and serious secondary pollution.

[0009] The dry process is the most common method for treating silicon smelting flue gas. Through the dust removal device, SiO2 can be recovered with high efficiency. The technology of this system is mature, but the disadvantage is that it cannot effectively remove harmful gases such as NOx in the flue gas.

[0010] Chinese Patent No. 201210052982.X discloses a flue gas purification and silicon micro powder recovery system for industrial silicon smelting electric furnaces. This technical solution is composed of a wet dust removal, desulfurization, dehydration integrated tower, a wet separation and densification tower, and a centrifugal spray drying tower arranged and connected in sequence. It has three functions of dust removal, desulfurization and dehydration, and can remove dust and SO2 emissions in the flue gas, but it does not achieve the removal of NOx, and the removed harmful sulfur and nitrate are not resourcefully disposed of.

[0011] The present invention aims to solve at least one of the technical problems in the related art to a certain extent.

[0012] Therefore, an embodiment of the first aspect of the present invention provides a method for treating silicon smelting flue gas, which can solve the problem of simultaneous treatment of multiple pollutants such as SiO2, SO2, and NOx in silicon smelting flue gas, and achieve the goal of respectively resourcefully utilizing pollutants such as SiO2, SO2, and NOx.

[0013] According to the method for treating silicon smelting flue gas of the embodiment of the first aspect of the present invention, it includes the following steps:

[0014] a. Pass the silicon smelting flue gas into a dust removal device for dust removal treatment;

[0015] b. Perform plasma oxidation on the flue gas treated by the dust removal device to oxidize NO in the flue gas into NO2;

[0016] c. Send the flue gas obtained after the treatment in step b into an absorption device. Add an oily absorption liquid from the top of the absorption device, add an alkali solution to the middle part, and pass air into the bottom of the absorption device. The flue gas undergoes a catalytic oxidation reaction in the absorption device and is stratified into two layers. The upper layer is the oily absorption liquid, and the lower layer is an aqueous solution containing nitrates and sulfates.

[0017] Advantages and technical effects brought by the independent claims of the embodiments according to the first aspect of the present invention: 1. In the method of the embodiment of the present invention, a dust removal device is first used to remove large particulate matters in the silicon smelting flue gas, so that the particle size of the particulate matters in the flue gas reaches below 1 μm, and the particulate matter removal rate can reach more than 99%; 2. In the method of the embodiment of the present invention, the plasma oxidation technology is adopted, which can quickly and effectively oxidize NO in the flue gas into NO2, effectively improving the denitrification rate; 3. In the method of the embodiment of the present invention, an oily absorbent liquid and an alkali solution are added to the absorption device. SO2 and NO2 in the flue gas react with water in the alkali solution to form sulfurous acid and nitrous acid, and then form a complex with the oily absorbent liquid and enter the oily absorbent liquid. At the same time, air is introduced into the absorption device. The sulfurous acid and nitrous acid complexed in the complex are oxidized by oxygen in the air into sulfuric acid and nitric acid and enter the aqueous phase, and the complex is restored to the original oily absorbent liquid. After the flue gas is treated by the absorption device, SO2 and NO in the flue gas can be effectively removed. x , realizing the simultaneous treatment of SO2 and NO x , with a sulfur and nitrogen removal rate greater than 95%, meeting the emission requirements of the flue gas.

[0018] The method for treating silicon smelting flue gas according to the embodiment of the first aspect of the present invention, further comprising step d of filtering and separating the lower aqueous solution to obtain ultrafine SiO2.

[0019] The method for treating silicon smelting flue gas according to the embodiment of the first aspect of the present invention, wherein the upper oily absorbent liquid obtained in step c is filtered and returned to the absorption device.

[0020] The method for treating silicon smelting flue gas according to the embodiment of the first aspect of the present invention, wherein in the plasma oxidation in step b, the pulse power duration is 100 - 300 ns (nanoseconds), and the variable frequency is 10 - 300 Hz.

[0021] The method for treating silicon smelting flue gas according to the embodiment of the first aspect of the present invention, wherein in step c, the oily absorbent liquid comprises:

[0022] 30 - 50% of 2-chloroethyl phenyl sulfoxide;

[0023] 10 - 30% of n-octane, cyclohexane or n-hexane;

[0024] 10 - 20% of n-butanol, isoamyl alcohol, n-hexanol;

[0025] 1 - 5% of cetyltrimethylammonium bromide;

[0026] 5 - 20% of deionized water;

[0027] Calculated by mass percentage.

[0028] The method for treating silicon smelting flue gas according to the embodiment of the first aspect of the present invention, wherein the alkaline solution is ammonia water, NaOH or KOH.

[0029] The embodiment of the second aspect of the present invention also provides a device for treating silicon smelting flue gas. The device includes a dust removal device, a plasma reactor, and the dust removal device is provided with a flue gas inlet and an outlet. The inlet of the plasma reactor is connected to the flue gas outlet of the dust removal device. The middle and lower part of the [device name] is provided with a flue gas inlet, the middle and upper part is provided with an alkaline solution inlet, the bottom is provided with an air inlet and an aqueous phase outlet, the lower part is provided with an oil phase outlet, and the top is provided with an absorbent liquid inlet and a flue gas outlet. The flue gas inlet is connected to the outlet of the plasma reactor.

[0030] According to the advantages and technical effects brought by the independent claims of the embodiment of the second aspect of the present invention: 1. The device of the embodiment of the present invention first uses a dust removal device to remove large particulate matter in the silicon smelting flue gas, so that the particle size of the particulate matter in the flue gas reaches below 1 μm, and the particulate matter removal rate can reach over 99%; 2. The plasma reactor is adopted in the device of the embodiment of the present invention, which can quickly and efficiently oxidize NO in the flue gas into NO2, effectively improving the denitrification rate; 3. For the device of the embodiment of the present invention, after the flue gas is treated, SO2 and NO in the flue gas can be effectively removed x , achieving the simultaneous treatment of SO2 and NO x , with a sulfur and nitrate removal rate greater than 95%, meeting the emission requirements of the flue gas; 4. The device of the embodiment of the present invention is simple, occupies less land area, and is easy to apply.

[0031] The device for treating silicon smelting flue gas according to the embodiment of the second aspect of the present invention, further includes a first separation device, and the inlet of the first separation device is connected to the aqueous phase outlet of the absorption device.

[0032] The device for treating silicon smelting flue gas according to the embodiment of the second aspect of the present invention, further includes a second separation device, and the inlet of the second separation device is connected to the oil phase outlet of the absorption device.

[0033] The device for treating silicon smelting flue gas according to the embodiment of the second aspect of the present invention, wherein the liquid phase outlet of the second separation device is connected to the absorbent liquid inlet of the absorption device. Description of the Drawings

[0034] Figure 1 It is a schematic diagram of the device for treating silicon smelting flue gas according to the embodiment of the present invention. Detailed Embodiments

[0035] It should be noted that there seems to be some information missing or unclear in the text, such as the name of the device in the description of the device structure in item . I have translated it as "[device name]" for the time being. You can provide more accurate information for a more precise translation.Embodiments of the present invention will be described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, and should not be construed as limiting the present invention.

[0036] A method for treating silicon smelting flue gas according to an embodiment of the first aspect of the present invention, which includes the following steps:

[0037] a. Pass the silicon smelting flue gas into a dust removal device for dust removal treatment;

[0038] b. Perform plasma oxidation on the flue gas treated by the dust removal device to oxidize NO in the flue gas into NO2. Preferably, the pulse power supply duration of the plasma oxidation is 100 - 300 ns, and the variable frequency is 10 - 300 Hz;

[0039] c. Send the flue gas obtained after the treatment in step b into an absorption device, add an oily absorption liquid from the top of the absorption device, add an alkali solution to the middle, and pass air into the bottom of the absorption device. The flue gas undergoes a catalytic oxidation reaction in the absorption device and is stratified into two layers. The upper layer is the oily absorption liquid, and the lower layer is an aqueous solution containing nitrates and sulfates. Preferably, the oily absorption liquid includes: 30 - 50% of 2-chloroethyl phenyl sulfoxide, 10 - 30% of n-octane, cyclohexane or n-hexane, 10 - 20% of n-butanol, isoamyl alcohol, n-hexanol, 1 - 5% of cetyltrimethylammonium bromide, and 5 - 20% of deionized water; preferably, the alkali solution is ammonia water, NaOH or KOH.

[0040] Advantages and technical effects brought by the independent claims according to an embodiment of the first aspect of the present invention: 1. The method of the embodiment of the present invention first uses a dust removal device to remove large particulate matter in the silicon smelting flue gas, so that the particle size of the particulate matter in the flue gas reaches below 1 μm, and the particulate matter removal rate can reach more than 99%; 2. The plasma oxidation technology is adopted in the method of the embodiment of the present invention, which can quickly and efficiently oxidize NO in the flue gas into NO2, effectively improving the denitrification rate; 3. In the method of the embodiment of the present invention, an oily absorption liquid and an alkali solution are added to the absorption device. SO2 and NO2 in the flue gas react with water in the alkali solution to form sulfurous acid and nitrous acid, and then form a complex with the oily absorption liquid and enter the oily absorption liquid. At the same time, air is introduced into the absorption device, and the sulfurous acid and nitrous acid complexed in the complex are oxidized by oxygen in the air into sulfuric acid and nitric acid. The nitric acid and sulfuric acid react with the alkali solution to be converted into corresponding nitrates and sulfates, thereby realizing the simultaneous recovery of sulfur and nitrate resources in the flue gas. The complex is restored to the original oily absorption liquid, and the aqueous solution containing nitrates and sulfates and the oily absorption liquid are naturally stratified in the absorption device. After the flue gas is treated by the absorption device, SO2 and NO in the flue gas can be effectively removed x , realizing SO2 and NO xSimultaneous treatment, with a sulfur and nitrate removal rate greater than 95%, meeting the flue gas emission requirements.

[0041] According to the method for treating silicon smelting flue gas according to the first aspect embodiment of the present invention, wherein the lower aqueous solution is filtered and separated by a separation device to obtain ultrafine SiO2. In the embodiment of the present invention, in the absorption device, due to the different densities of the aqueous solution and the oily absorbent, the aqueous solution is located in the lower layer during stratification, and the ultrafine SiO2 that cannot be collected by the dust removal device also enters the aqueous phase. When the nitrate and sulfate reach a certain concentration in the aqueous solution, preferably, when the salt concentration reaches 20%-35% (by mass), the lower aqueous solution is discharged from the absorption device, and the ultrafine SiO2 is separated by the separation device, and the remaining liquid can be evaporated and concentrated to recover sulfur and nitrate resources. Further, the upper oily absorbent is filtered through the separation device and then returned to the absorption device for repeated circulation use.

[0042] As Figure 1 shown, according to the silicon smelting flue gas treatment device of the second aspect embodiment of the present invention, the device includes a dust removal device 1, a plasma reactor 2 and 3. The dust removal device 1 is provided with a flue gas inlet and an outlet. The inlet of the plasma reactor 2 is connected to the flue gas outlet of the dust removal device 1. The middle and lower part of the 3 is provided with a flue gas inlet, the middle and upper part is provided with an alkali liquid inlet, the bottom is provided with an air inlet and an aqueous phase outlet, the lower part is provided with an oil phase outlet, and the top is provided with an absorbent inlet and a flue gas outlet. The flue gas inlet of the 3 is connected to the outlet of the plasma reactor 2.

[0043] According to the advantages and technical effects brought by the independent claims of the second aspect embodiment of the present invention, 1. The device of the embodiment of the present invention first uses a dust removal device to remove large particulate matter in the silicon smelting flue gas, so that the particle size of the particulate matter in the flue gas reaches below 1 μm, and the particulate matter removal rate can reach more than 99%; 2. The plasma reactor is used in the device of the embodiment of the present invention, which can quickly and efficiently oxidize NO in the flue gas to NO2, effectively improving the denitrification rate; 3. The device of the embodiment of the present invention can effectively remove SO2 and NO in the flue gas after the flue gas is treated x , realizing the simultaneous treatment of SO2 and NO x , with a sulfur and nitrate removal rate greater than 95%, meeting the flue gas emission requirements; 4. The device of the embodiment of the present invention is simple, occupies less land area, and is easy to apply.

[0044] According to the silicon smelting flue gas treatment device of the second aspect embodiment of the present invention, wherein the dust removal device 1 is preferably a bag dust removal device; the 3 is preferably an absorption tower.

[0045] The treatment device for silicon smelting flue gas according to the embodiment of the second aspect of the present invention further includes a first separation device 4, and the inlet of the first separation device 4 is connected to the aqueous phase outlet of the [device 3]. After the flue gas is treated by the dust removal device, the ultrafine SiO2 that cannot be treated by the dust removal device will enter the subsequent absorption tower device along with the flue gas. After treatment, the ultrafine SiO2 enters the aqueous phase. In the embodiment of the present invention, the aqueous phase in [the relevant part] is discharged for filtration and separation, and ultrafine SiO2 can be recovered.

[0046] The treatment device for silicon smelting flue gas according to the embodiment of the second aspect of the present invention further includes a concentration device 5, and the inlet of the evaporation concentration device 5 is connected to the liquid phase outlet of the first separation device 4. After the aqueous phase in [the relevant part] is separated, the evaporation concentration device is used to concentrate the aqueous phase, and a sulfur-nitrate mixed salt can be obtained.

[0047] The treatment device for silicon smelting flue gas according to the embodiment of the second aspect of the present invention further includes a second separation device 6, and the inlet of the second separation device 6 is connected to the oil phase outlet of the [device 3]. Further preferably, the liquid phase outlet of the second separation device 6 is connected to the absorption liquid inlet of the [device 3]. The oil phase obtained in [the relevant part] is filtered to recover the oily absorption liquid in the absorption liquid, and the filtered oily absorption liquid is returned for repeated recycling.

[0048] Example 1

[0049] Take 10000 Nm 3 / h of flue gas from a silicon smelting furnace, where the NOx concentration is 630 mg / Nm 3 , the SO2 concentration is 720 mg / Nm 3 , the dust content is 1200 mg / m 3 , and the flue gas temperature is 160 °C.

[0050] The flue gas enters the bag dust removal device 1. After dust removal treatment, the large particle SiO2 in the flue gas is filtered and collected to form a SiO2 by-product, and the dust removal efficiency can reach 99.5%.

[0051] The flue gas after dust removal treatment enters the plasma reactor 2 after being boosted by a booster fan. The pulse power supply duration is 100 ns, the variable frequency is 50 Hz, and the maximum peak voltage is 50 kV. The plasma reactor 2 is in a discharge state, the molecules in the flue gas are excited, and NO mainly undergoes an oxidation reaction with O2 in the flue gas, and most of the NO is oxidized to the higher valence NO2.

[0052] The flue gas treated by the plasma reactor 2 enters the absorption tower 3 from the flue gas inlet in the middle and lower part of the integrated absorption tower 3. The absorption tower 3 is a spray tower with an empty tower structure. The oily absorption liquid enters the tower through the top absorption liquid inlet of the integrated absorption tower 3. The oily absorption liquid is composed of 46% 2-chloroethylphenyl sulfoxide, 20% cyclohexane, 18% isoamyl alcohol, 4% cetyltrimethylammonium bromide, and 12% deionized water. Ammonia water is added through the alkali liquid inlet in the upper-middle part of the absorption tower 3 to control the pH value of the slurry pool in the absorption tower to be 5 - 6. Air is introduced through the air inlet at the bottom of the absorption tower 3. The main function of the oily absorption liquid in the tower is to promote absorption and oxidation. SO2 and NO2 react with the water in the ammonia water to form sulfurous acid and nitrous acid, and then form complexes with the oily absorption liquid and enter the oily absorption liquid. The sulfurous acid and nitrous acid complexed in the complex are oxidized by the oxygen in the air to sulfuric acid and nitric acid. Nitric acid and sulfuric acid react with ammonia water to be converted into ammonium nitrate and ammonium sulfate and enter the aqueous phase. At the same time, oxygen can also oxidize part of the ammonium nitrite and ammonium sulfite formed by the reaction of SO2 and NO2 with ammonia water to ammonium nitrate and ammonium sulfate. After the sulfurous acid and nitrous acid complexed in the complex are oxidized by oxygen, the complex returns to the oily absorption liquid. The aqueous solution containing nitrates and sulfates and the oily absorption liquid are naturally stratified in the absorption tower 3. Due to the different densities of the aqueous solution and the oily absorption liquid, the aqueous solution is located in the lower layer during stratification. The ultrafine SiO2 that cannot be collected by the bag filter also enters the aqueous phase. When the salt concentration in the lower aqueous solution reaches 25% (by mass), it is discharged out of the tower and enters the evaporation and concentration device 5 after being filtered by the first separation device 4. Sulfur-nitrogen mixed salt is obtained after evaporation and concentration. The filter residue of the first separation device 4 is ultrafine SiO2. The upper-layer oily absorption liquid in the absorption tower 3 enters the second separation device 6 for filtration treatment and then returns to the integrated absorption tower 3 for repeated circulation. The flue gas is discharged from the top of the absorption tower. The NOx concentration in the flue gas is 30mg / Nm 3 , the SO2 concentration is 25mg / Nm 3 , the dust content is 5mg / m 3 , the denitrification rate is 95.2%, the desulfurization rate is 96.5%, and the dust removal rate is 99.6%.

[0053] Example 2

[0054] The method is the same as that of Example 1, except that the oily absorption liquid in the absorption tower 3 is composed of 36% 2-chloroethylphenyl sulfoxide, 28% n-octane, 16% isoamyl alcohol, 5% cetyltrimethylammonium bromide, and 15% deionized water.

[0055] After being treated by the method of Example 2, the NOx concentration in the flue gas is 31mg / Nm 3 , the SO2 concentration is 27mg / Nm 3 , the dust content is 5mg / m 3, the denitrification rate is 95.1%, the desulfurization rate is 96.3%, and the dust removal rate is 99.6%.

[0056] Comparative Example 1

[0057] The method is the same as that of Example 1, except that after the flue gas is treated by the dust removal device, hydrogen peroxide is used for oxidation treatment instead of using the plasma reactor for oxidation.

[0058] After being treated by the method of Comparative Example 1, the NOx concentration in the flue gas is 138 mg / Nm 3 , the SO2 concentration is 25 mg / Nm 3 , the dust content is 5 mg / m 3 , the denitrification rate is 78.1%, the desulfurization rate is 96.5%, and the dust removal rate is 99.6%.

[0059] Comparative Example 2

[0060] The method is the same as that of Example 1, except that the oily absorbent is 46% dimethyl sulfoxide, 20% cyclohexane, 18% isoamyl alcohol, 4% cetyltrimethylammonium bromide, and 12% deionized water.

[0061] After being treated by the method of Comparative Example 2, the NOx concentration in the flue gas is 115 mg / Nm 3 , the SO2 concentration is 28 mg / Nm 3 , the dust content is 5 mg / m 3 , the denitrification rate is 81.7%, the desulfurization rate is 96.1%, and the dust removal rate is 99.6%.

[0062] In the present invention, unless otherwise clearly defined and limited, terms such as "installation", "connection", "connection", "fixation" and other terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection, an electrical connection or communication with each other; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0063] In the present invention, unless otherwise clearly specified or limited, the first feature being "on" or "under" the second feature may mean that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Also, the first feature being "above", "over" and "on top of" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "below" and "beneath" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the horizontal height of the first feature is less than that of the second feature.

[0064] In the present invention, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0065] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for treating silicon smelting flue gas, characterized in that, It includes the following steps: a. Pass the silicon smelting flue gas into a dust removal device for dust removal treatment; b. Perform plasma oxidation on the flue gas treated by the dust removal device to oxidize NO in the flue gas into NO2; c. Send the flue gas obtained after the treatment in step b into an absorption device, add an oily absorption liquid from the top of the absorption device, add an alkali solution to the middle of the absorption device, and pass air into the bottom of the absorption device. The flue gas undergoes a catalytic oxidation reaction in the absorption device and is stratified to form two layers. The upper layer is the oily absorption liquid, and the lower layer is an aqueous solution containing nitrates and sulfates. Among them, the composition of the oily absorption liquid is: 36 - 50% of 2-chloroethyl phenyl sulfoxide; 20 - 28% of n-octane or cyclohexane; 16 - 18% of isoamyl alcohol; 4 - 5% of cetyltrimethylammonium bromide; 5 - 20% of deionized water; Based on mass percentage.

2. The treatment method of silicon smelting flue gas according to claim 1, characterized in that It further includes step d of filtering and separating the lower aqueous solution to obtain ultrafine SiO2.

3. The treatment method of silicon smelting flue gas according to claim 1, wherein Filter the upper oily absorption liquid obtained in step c and return it to the absorption device.

4. The treatment method of silicon smelting flue gas according to claim 1, characterized in that, In the plasma oxidation in step b, the pulse power supply duration is 100 - 300 ns, and the variable frequency is 10 - 300 Hz.

5. The method for treating silicon smelting flue gas according to claim 1, characterized in that, The alkali solution is ammonia water, NaOH or KOH.

6. The method for treating silicon smelting flue gas according to claim 1, wherein, The device used in the treatment method includes a dust removal device, a plasma reactor and an absorption device. The dust removal device is provided with a flue gas inlet and an outlet. The plasma reactor inlet is connected to the flue gas outlet of the dust removal device. The flue gas inlet is arranged in the middle and lower part of the absorption device, the alkali solution inlet is arranged in the middle and upper part, the air inlet and the aqueous phase outlet are arranged at the bottom, the oil phase outlet is arranged at the lower part, and the absorption liquid inlet and the flue gas outlet are arranged at the top. The flue gas inlet of the absorption device is connected to the outlet of the plasma reactor.

7. The method for treating silicon smelting flue gas according to claim 6, characterized in that, The device used in the treatment method further includes a first separation device, and the inlet of the first separation device is connected to the aqueous phase outlet of the absorption device.

8. The method for treating silicon smelting flue gas according to claim 6, wherein, The device used in the treatment method further includes a second separation device, and the inlet of the second separation device is connected to the oil phase outlet of the absorption device.

9. The treatment method of silicon smelting flue gas according to claim 8, characterized in that, The liquid phase outlet of the second separation device is connected to the absorption liquid inlet of the absorption device.

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