Recovery device for waste salt generated in polycrystalline silicon production

Abstract

The utility model discloses a device for recovering waste salt generated in polycrystalline silicon production, relates to the technical field of polycrystalline silicon waste treatment equipment, and mainly aims to provide a device for recovering waste salt generated in polycrystalline silicon production, which can remove metal ions and organic matters in high-salinity wastewater. According to the main technical scheme, the device for recovering the waste salt generated in the polycrystalline silicon production comprises an organic matter treatment part, two ends of a baffling tank are respectively connected to a salt dissolving tank and a first reaction tank, and a feeding part is arranged at the upper part of the baffling tank and is used for introducing sodium hypochlorite and sodium hydroxide; two ends of the deionization component and the mixer are respectively connected to the first reaction tank and the second reaction tank, the upper part of the mixer is provided with a sodium sulfite feeding pipe, two ends of the buffer tank are respectively connected to the second reaction tank and the membrane filter, and the chlor-alkali treatment component is connected to the membrane filter. The device is mainly used for waste salt treatment.

Description

Technical Field

[0001] The utility model relates to the technical field of polysilicon waste processing equipment, in particular to a waste salt recovery device generated by polysilicon production. Background Art

[0002] In the process of producing polysilicon using the Siemens method, the source of high-salt wastewater is mainly the slag slurry and chlorosilane-containing waste gas generated in the polysilicon production process, which are hydrolyzed into chlorine-containing acidic wastewater and silicon dioxide. The acidic wastewater is neutralized with alkaline solution to form high-salt wastewater. The high-salt wastewater contains a small amount of calcium and magnesium impurities and a large amount of sodium chloride.

[0003] The existing treatment method for high-salt wastewater is mainly to treat it through the evaporation crystallization process. The secondary steam from the flash evaporation passes through the gas phase pipeline upward in the crystallization separator, enters the secondary separator to separate the droplets entrained by the gas, and the steam enters the compressor for compression. The concentrated liquid after gas-liquid separation in the separator begins to discharge after reaching the saturated concentration. The concentrated liquid containing crystals is pumped to the thickener through the discharge pump, and separated by the centrifuge to obtain the crystalline salt, which is solid sodium chloride. Since the front-end material contains organic matter, metal ions and other impurities, and the material is hydrolyzed, the waste salt finally produced contains a high content of organic silicon dioxide and metal ions. The salt can only be treated as general solid waste. In addition, the waste salt produced by the evaporation crystallization device contains organic matter, metal ions and other impurities and cannot be directly used as raw salt in the chlor-alkali process, and can only be treated as general solid waste. There are certain limitations in the process of treating the original primary brine. The relevant metal ions and other impurities can be removed in this process, but the organic matter cannot be removed, so the waste salt cannot be recycled. The evaporation crystallization process has high operation and cost. The waste salt needs to be sent to other places for treatment as solid waste at a certain cost, which increases the pressure on environmental protection, invisibly increases the operation and maintenance costs of the entire polysilicon production line, and reduces the economic benefits of the polysilicon production line. Utility Model Content

[0004] In view of this, an embodiment of the utility model provides a waste salt recovery device generated by polysilicon production, the main purpose of which is to provide a waste salt recovery device generated by polysilicon production that can remove metal ions and organic matter in high-salt wastewater.

[0005] In order to achieve the above purpose, the utility model mainly provides the following technical solutions:

[0006] The present invention provides a device for recovering waste salt generated by polysilicon production, the device comprising:

[0007] An organic matter treatment component, the organic matter treatment component comprises a salt treatment tank, a feed component, a baffle groove and a first reaction tank, the two ends of the baffle groove are respectively connected to the salt treatment tank and the first reaction tank, and the feed component is arranged on the upper part of the baffle groove for introducing sodium hypochlorite and sodium hydroxide;

[0008] The ion removal component includes a mixer, a second reaction tank, a buffer tank, a membrane filter and a chlor-alkali treatment component, wherein both ends of the mixer are respectively connected to the first reaction tank and the second reaction tank, a sodium sulfite feed pipe is arranged on the upper part of the mixer, both ends of the buffer tank are respectively connected to the second reaction tank and the membrane filter, and the chlor-alkali treatment component is connected to the membrane filter.

[0009] Furthermore, the feeding component includes a mixer, a sodium hypochlorite feeding pipe and a sodium hydroxide feeding pipe. The sodium hypochlorite feeding pipe and the sodium hydroxide feeding pipe are arranged on the upper part of the mixer, and the lower part of the mixer is connected to the upper part of the baffle tank.

[0010] Furthermore, a distributor is arranged at the bottom of the salting pool, and a plurality of first through holes are arranged on the distributor.

[0011] Furthermore, a detection component comprises a first detection component and a second detection component, wherein the first detection component is arranged between the first reaction tank and the mixer, and the second detection component is arranged between the second reaction tank and the buffer tank.

[0012] Furthermore, the deionizing component also includes a sodium carbonate feed pipe, and the sodium carbonate feed pipe is arranged on the upper part of the second reaction tank.

[0013] Furthermore, the mixer is a Venturi mixer.

[0014] Furthermore, the chlor-alkali treatment component includes a refined brine tank and a secondary refining component, and the secondary refining component is connected to the refined brine tank.

[0015] Furthermore, the chlor-alkali treatment component also includes an electrolysis component, and the electrolysis component is connected to the secondary refining component.

[0016] Compared with the prior art, the utility model has the following technical effects:

[0017] In the technical solution provided by the embodiment of the utility model, the function of the organic matter treatment component is to remove organic matter and magnesium ions in high-salt wastewater, and the organic matter treatment component includes a salt tank, a feeding component, a baffle groove and a first reaction tank, the two ends of the baffle groove are respectively connected to the salt tank and the first reaction tank, and the feeding component is arranged on the upper part of the baffle groove for introducing sodium hypochlorite and sodium hydroxide; the function of the deionization component is to remove chloride ions and calcium ions in high-salt wastewater, and the deionization component includes a mixer, a second reaction tank, a buffer tank, a membrane filter and a chlor-alkali treatment component, the two ends of the mixer are respectively connected to the first reaction tank and the second reaction tank, a sodium sulfite feeding pipe is arranged on the upper part of the mixer, the two ends of the buffer tank are respectively connected to the second reaction tank and the membrane filter, and the chlor-alkali treatment component is connected to the membrane filter. Compared with the prior art, the treatment is carried out through an evaporation crystallization process, and the secondary steam through flash evaporation passes upward through the gas phase pipeline in the crystallization separator, enters the secondary separator to separate the droplets entrained by the gas, and the steam enters the compressor for compression. After the gas-liquid separation in the separator, the concentrated liquid starts to be discharged after reaching the saturated concentration. The concentrated liquid containing crystals is pumped to the thickener through the discharge pump, and separated by the centrifuge to obtain the crystalline salt, which is solid sodium chloride. Since the front-end material contains organic matter, metal ions and other impurities, and the material is hydrolyzed, the final waste salt contains a high content of organic silica and metal ions. The salt can only be treated as general solid waste. In addition, the waste salt produced as a by-product of the evaporation crystallization device contains organic matter, metal ions and other impurities and cannot be directly used as raw salt in the chlor-alkali process, but can only be treated as general solid waste. The original primary brine process has certain limitations. The process can remove related metal ions and other impurities, but cannot remove organic matter, so the waste salt cannot be recycled.The evaporation crystallization process has high operation and cost. The waste salt needs to be sent to other places for treatment as solid waste at a certain cost, which increases the pressure on environmental protection, invisibly increases the operation and maintenance cost of the entire polysilicon production line, and reduces the economic benefits of the polysilicon production line. In this technical solution, the waste salt generated by the evaporation crystallization device is added to the salt tank for saltization to form saturated brine after screening and dehydration, and then enters the baffle tank. At the same time, a mixture of sodium hypochlorite and sodium hydroxide is mixed with the saturated brine and then passed into the first reaction tank for reaction. Sodium hypochlorite oxidizes organic matter in the brine, and sodium hydroxide reacts with magnesium ions in the brine to form magnesium hydroxide, thereby removing magnesium. ions, and then passed into a mixer, sodium sulfite is added to the mixer, and then passed into a second reaction tank for reaction, free chlorine generated in the brine is removed, sodium carbonate reacts with calcium ions to form calcium carbonate precipitates, and the brine enters a membrane filter and a chlor-alkali treatment component for subsequent treatment, which not only removes organic matter in the brine, but also removes magnesium ions and calcium ions in the brine, and at the same time removes free chlorine generated by excess sodium hypochlorite, which not only reduces the amount of solid waste disposal, but also enables waste salt to be recycled for use in the polysilicon production system, reduces the problem of waste material disposal, and also reduces the economic loss caused by waste treatment, thereby achieving the technical effect of improving environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A method flow chart provided for an embodiment of the utility model. DETAILED DESCRIPTION

[0019] The utility model is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0020] like Figure 1 As shown, the embodiment of the utility model provides a waste salt recovery device generated by polysilicon production, the device comprising:

[0021] The organic matter treatment component includes a salt treatment tank 11, a feed component, a baffle 13 and a first reaction tank 14. The two ends of the baffle 13 are respectively connected to the salt treatment tank 11 and the first reaction tank 14. The upper part of the baffle 13 is provided with a feed component for introducing sodium hypochlorite and sodium hydroxide.

[0022] The ion removal component includes a mixer 21, a second reaction tank 22, a buffer tank 23, a membrane filter 24 and a chlor-alkali treatment component. The two ends of the mixer 21 are respectively connected to the first reaction tank 14 and the second reaction tank 22. A sodium sulfite feed pipe 211 is arranged on the upper part of the mixer 21. The two ends of the buffer tank 23 are respectively connected to the second reaction tank 22 and the membrane filter 24. The chlor-alkali treatment component is connected to the membrane filter 24.

[0023] In the technical solution provided by the embodiment of the utility model, the function of the organic matter treatment component is to remove organic matter and magnesium ions in high-salt wastewater. The organic matter treatment component includes a salt tank 11, a feeding component, a baffle trough 13 and a first reaction tank 14. The two ends of the baffle trough 13 are respectively connected to the salt tank 11 and the first reaction tank 14. The upper part of the baffle trough 13 is provided with a feeding component for passing sodium hypochlorite and sodium hydroxide; the function of the deionization component is to remove chloride ions and calcium ions in high-salt wastewater. The deionization component includes a mixer 21, a second reaction tank 22, a buffer tank 2 3. Membrane filter 24 and chlor-alkali treatment component. The two ends of the mixer 21 are respectively connected to the first reaction tank 14 and the second reaction tank 22. A sodium sulfite feed pipe 211 is arranged on the upper part of the mixer 21. The two ends of the buffer tank 23 are respectively connected to the second reaction tank 22 and the membrane filter 24. The chlor-alkali treatment component is connected to the membrane filter 24. Compared with the prior art, the evaporation crystallization process is used for treatment. The secondary steam through flash evaporation passes through the gas phase pipeline upward in the crystallization separator and enters the secondary separator to separate the droplets entrained by the gas. The steam enters the compressor for compression. The concentrated liquid after gas-liquid separation in the separator starts to be discharged after reaching the saturated concentration. The concentrated liquid containing crystals is pumped to the thickener through the discharge pump and separated by the centrifuge to obtain the crystallized salt, which is solid sodium chloride. Since the front-end materials contain organic matter, metal ions and other impurities, and the materials are hydrolyzed, the waste salt produced finally contains high organic silica and metal ions. The salt can only be treated as general solid waste. In addition, the waste salt produced as a by-product of the evaporation crystallization device contains organic matter, metal ions and other impurities and cannot be directly used as raw salt in the chlor-alkali process. It can only be treated as general solid waste. The original primary brine process has certain limitations. The process can remove related metal ions and other impurities, but cannot remove organic matter, so the waste salt cannot be recycled.The evaporation crystallization process has high operation and cost. The waste salt needs to be sent to other places for treatment as solid waste at a certain cost, which increases the pressure on environmental protection, invisibly increases the operation and maintenance cost of the entire polysilicon production line, and reduces the economic benefits of the polysilicon production line. In this technical solution, the waste salt generated by the evaporation crystallization device is added to the salt tank 11 for salting to form saturated brine after screening and dehydration, and then enters the baffle 13. At the same time, the mixture of sodium hypochlorite and sodium hydroxide is mixed with the saturated brine and then passed into the first reaction tank 14 for reaction. The effective chlorine of sodium hypochlorite must be guaranteed to be 10%±1%, and the usage of sodium hypochlorite and the free chlorine control index of the system are reasonably guaranteed. Sodium hypochlorite oxidizes organic matter in the brine, and sodium hydroxide The salt water reacts with magnesium ions in the brine to generate magnesium hydroxide, and the magnesium ions are removed. Then, the salt water is introduced into the mixer 21, sodium sulfite is added into the mixer 21, and then the salt water is introduced into the second reaction tank 22 for reaction to remove free chlorine generated in the brine. Sodium carbonate reacts with calcium ions to generate calcium carbonate precipitate. The brine enters the membrane filter 24 and the chlor-alkali treatment component for subsequent treatment, which not only removes organic matter in the brine, but also removes magnesium ions and calcium ions in the brine, and removes free chlorine generated by excess sodium hypochlorite, which not only reduces the amount of solid waste disposal, but also enables waste salt to be recycled into the polysilicon production system for use, reduces the waste disposal problem of materials, and also reduces the economic loss caused by waste disposal, thereby achieving the technical effect of improving environmental protection.

[0024] The comparison of industrial granular raw salt and waste salt sample data is shown in Table 1:

[0025]

[0026]

[0027] Table 1

[0028] The chlor-alkali process ion membrane electrolyzer is used to generate 340m3 of saturated brine. 3 , the electrolytic cell load is 14.3KA, and the waste salt generated by the evaporation crystallization device is all sent to the chlor-alkali process for recycling. The daily use of sodium hypochlorite (10%) is 360kg, which is added to the baffle 13 and enters the first reaction tank 14 for full reaction. The COD of the salt water after the final reaction is all 0. Due to the addition of excessive sodium hypochlorite, there will be a certain amount of free chlorine in the salt water. Adding sodium sulfite in the venturi mixer 21 will eventually completely remove the free chlorine. The data is shown in Table 2:

[0029]

[0030] Table 2

[0031] After the COD of the refined brine entering the electrolysis component dropped to 0, the electrolytic cell voltage remained stable, with the indicator range of 191.04-191.59V. The data are shown in Table 3:

[0032]

[0033]

[0034] Table 3

[0035] The function of the organic matter treatment component is to remove organic matter and magnesium ions in high-salt wastewater. The organic matter treatment component includes a salt treatment tank 11, a feeding component, a baffle trough 13 and a first reaction tank 14. The two ends of the baffle trough 13 are respectively connected to the salt treatment tank 11 and the first reaction tank 14. A feeding component is arranged on the upper part of the baffle trough 13 for introducing sodium hypochlorite and sodium hydroxide. The waste salt produced by the evaporation crystallization device is fine-grained salt after screening and dehydration. The waste salt is transported to the salt field and further dehydrated by air drying, and then the waste salt is added to the salt treatment tank 11. Then, the light salt water prepared by dechlorination after electrolysis is added to the salt treatment tank 11. A distributor is arranged at the bottom of the salt treatment tank 11, and a plurality of first through holes are arranged on the distributor. In addition, the material of the bottom of the distributor is titanium. The waste salt is melted into saturated brine, and then the saturated brine is transported to the baffle trough 13. Specifically, the feeding component includes a mixer 121, a sodium hypochlorite feed pipe 122 and a sodium hydroxide feed pipe 123. The mixer A sodium hypochlorite feed pipe 122 and a sodium hydroxide feed pipe 123 are arranged at the upper part of 121, and the lower part of the mixer 121 is connected to the upper part of the baffle tank 13. The sodium hypochlorite feed pipe 122 and the sodium hydroxide feed pipe 123 respectively add sodium hypochlorite and sodium hydroxide into the mixer 121 for mixing, and then pass into the baffle tank 13, so that the sodium hypochlorite, sodium hydroxide and salt water are mixed and enter the first reaction tank 14 for reaction. In addition, a stirring device needs to be arranged in the first reaction tank 14 to make it fully react. Sodium hypochlorite oxidizes organic matter in the salt water and removes COD (COD is the oxygen equivalent of substances that can be oxidized by strong oxidants in wastewater, effluent from wastewater treatment plants and contaminated water). The principle of removing COD is that organic matter in the salt water is oxidized and decomposed into small molecules by the strong oxidant sodium hypochlorite. The oxidizing property of the sodium hypochlorite aqueous solution is achieved by the hypochlorous acid produced by hydrolysis. After the hypochlorous acid oxidizes the organic matter, it becomes chloride ions and water. The specific reaction formula is as follows:

[0036] NaClO+macromolecule organic matter→NaCl+H2O+small molecule organic matter / (CO2↑+H2O)

[0037] Sodium hydroxide reacts with magnesium ions in brine to form magnesium hydroxide. The principle of sodium hydroxide removing magnesium ions:

[0038] Mg 2+ +2OH -→Mg(OH)2↓

[0039] Thereby, the effect of removing magnesium ions is achieved; the effect of the deionization component is to remove chloride ions and calcium ions in high-salt wastewater. The deionization component includes a mixer 21, a second reaction tank 22, a buffer tank 23, a membrane filter 24 and a chlor-alkali treatment component. The two ends of the mixer 21 are respectively connected to the first reaction tank 14 and the second reaction tank 22. A sodium sulfite feeding pipe 211 is arranged on the upper part of the mixer 21. The deionization component also includes a sodium carbonate feeding pipe. A sodium carbonate feeding pipe is arranged on the upper part of the second reaction tank 22 for adding sodium carbonate to the second reaction tank 22. The two ends of the buffer tank 23 are respectively connected to the second reaction tank 22 and the membrane filter 24. The chlor-alkali treatment component is connected to the membrane filter 24. Then, the brine from which COD is removed is passed into the mixer 21, sodium sulfite is added to the mixer 21, and then passed into the second reaction tank 22 for reaction to remove free chlorine generated in the brine. The principle of removing free chlorine is that free chlorine in brine generally exists as ClO-. Sodium sulfite is used to remove free chlorine in the production process, and the following reaction occurs:

[0040] ClO-+Na2SO3→Na2SO4+Cl-,

[0041] Sodium carbonate reacts with calcium ions to form calcium carbonate precipitates. The principle of sodium carbonate removing calcium ions:

[0042] Na2CO3+CaCl2→CaCO3↓+NaCl,

[0043] The brine enters the membrane filter 24 and the chlor-alkali treatment component for subsequent treatment, which not only removes organic matter in the brine, but also removes magnesium ions and calcium ions in the brine, and removes free chlorine produced by excess sodium hypochlorite, which not only reduces the amount of solid waste disposal, but also enables waste salt to be recycled into the polysilicon production system for use, reduces the problem of waste disposal of materials, and reduces the economic losses caused by waste treatment, thereby achieving the technical effect of improving environmental protection.

[0044] Furthermore, the detection component includes a first detection component 31 and a second detection component 32 , the first detection component 31 is arranged between the first reaction tank 14 and the mixer 21 , and the second detection component is arranged between the second reaction tank 22 and the buffer tank 23 . In this embodiment, a detection component is added. The function of the detection component is to detect the chloride ions in the salt water. The first detection component 31 and the second detection component 32 adopt the existing ORP detector (Oxidation-Reduction Potential, referred to as ORP). The ORP detector is an instrument for detecting the redox potential of the solution. It can accurately indicate the macroscopic redox properties of all substances in the solution. The first detection component 31 is arranged between the first reaction tank 14 and the mixer 21. Since excessive sodium hypochlorite is added in the modesty process, a large amount of free chlorine will be generated in the first reaction tank 14. The mixer 21 is a Venturi mixer 21. Sodium sulfite is added to the mixer 21. The sodium sulfite is mixed with the salt water through the mixer 21 and then enters the second reaction tank 22. Then sodium carbonate is added to the second reaction tank 22. Sodium sulfite removes free chlorine in the salt water. Sodium carbonate reacts with calcium ions to form calcium carbonate precipitation, thereby achieving the function of removing chloride ions and calcium ions.

[0045] Furthermore, the chlor-alkali treatment component includes a refined brine tank 251, a secondary refining component 252 and an electrolytic component 253, and the secondary refining component 252 is connected to the refined brine tank 251. In this embodiment, the chlor-alkali treatment component is further defined, and the brine enters the refined brine tank 251 after being filtered by the membrane filter 24, and then is processed by the secondary refining component 252. Specifically, the chlor-alkali treatment component also includes an electrolytic component 253, and the electrolytic component 253 is connected to the secondary refining component 252. The electrolytic component 253 adopts an ion membrane electrolytic cell. The brine discharged from the secondary refining component 252 is electrolytically treated by the electrolytic component 253, and can replace granular salt for production and use, which not only reduces the amount of solid waste disposal, but also enables the waste salt to be recycled and used in the polysilicon production system, reduces the waste disposal problem of materials, and also reduces the economic losses caused by waste treatment, thereby achieving the technical effect of improving environmental protection.

[0046] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the utility model, which should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.

Claims

1. A waste salt recovery device generated by polysilicon production, characterized in that: include: An organic matter treatment component, the organic matter treatment component comprises a salt treatment tank, a feed component, a baffle groove and a first reaction tank, the two ends of the baffle groove are respectively connected to the salt treatment tank and the first reaction tank, and the feed component is arranged on the upper part of the baffle groove for introducing sodium hypochlorite and sodium hydroxide; The ion removal component includes a mixer, a second reaction tank, a buffer tank, a membrane filter and a chlor-alkali treatment component, wherein both ends of the mixer are respectively connected to the first reaction tank and the second reaction tank, a sodium sulfite feed pipe is arranged on the upper part of the mixer, both ends of the buffer tank are respectively connected to the second reaction tank and the membrane filter, and the chlor-alkali treatment component is connected to the membrane filter.

2. The device for recovering waste salt generated by polysilicon production according to claim 1, characterized in that: The feeding component comprises a mixer, a sodium hypochlorite feeding pipe and a sodium hydroxide feeding pipe. The sodium hypochlorite feeding pipe and the sodium hydroxide feeding pipe are arranged on the upper part of the mixer, and the lower part of the mixer is connected to the upper part of the baffle tank.

3. The waste salt recovery device generated by polysilicon production according to claim 2, characterized in that: A distributor is arranged at the bottom of the salting pool, and a plurality of first through holes are arranged on the distributor.

4. The device for recovering waste salt generated by polysilicon production according to claim 2, characterized in that: Also includes: The detection component includes a first detection component and a second detection component, wherein the first detection component is arranged between the first reaction tank and the mixer, and the second detection component is arranged between the second reaction tank and the buffer tank.

5. The device for recovering waste salt generated by polysilicon production according to claim 2, characterized in that: The deionizing component also includes a sodium carbonate feed pipe, and the sodium carbonate feed pipe is arranged on the upper part of the second reaction tank.

6. A waste salt recovery device generated by polysilicon production according to any one of claims 1 to 5, characterized in that: The mixer is a Venturi mixer.

7. A waste salt recovery device generated by polysilicon production according to any one of claims 1 to 5, characterized in that: The chlor-alkali treatment component includes a refined brine tank and a secondary refining component, and the secondary refining component is connected to the refined brine tank.

8. The device for recovering waste salt generated by polysilicon production according to claim 7, characterized in that: The chlor-alkali treatment component further includes an electrolysis component, and the electrolysis component is connected to the secondary refining component.

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