CN210122524U - System for treating wastewater - Google Patents
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- CN210122524U CN210122524U CN201920724590.0U CN201920724590U CN210122524U CN 210122524 U CN210122524 U CN 210122524U CN 201920724590 U CN201920724590 U CN 201920724590U CN 210122524 U CN210122524 U CN 210122524U
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Abstract
The utility model discloses a system for handle waste water, this system includes: the neutralization device is provided with a waste acid inlet, an alkali liquor inlet and a neutralized waste water outlet; a first settling device having an acid-containing wastewater inlet, a neutralized wastewater inlet, a settling agent inlet, and a post-settling mixture outlet; a filtration device having a post-settling mixture inlet, a waste residue outlet, and a waste liquid outlet; a second settling device having a spent caustic inlet, a supernatant outlet, and a settled sludge outlet; the mixing device is provided with a supernatant inlet, an alkali-containing wastewater inlet, a waste liquid inlet and an alkali liquor preparation outlet, and the alkali liquor preparation outlet is connected with the alkali liquor inlet. By adopting the system, the treatment capacity of the pickling wastewater can be reduced by 60%, the water consumption can be saved by 50%, the consumption of new alkali can be reduced by 50%, and the system has excellent economic and environmental benefits.
Description
Technical Field
The utility model belongs to polycrystalline silicon production field particularly, the utility model relates to a system for handle waste water.
Background
Polycrystalline silicon is an important basic material in the information industry and solar photovoltaics and is a strategic material in China. At present, the domestic polycrystalline silicon is mainly produced by adopting an improved Siemens method. The improved Siemens method is characterized in that trichlorosilane and hydrogen are subjected to vapor deposition reaction in a CVD reduction furnace, and a polysilicon rod is deposited on a prefabricated silicon core.
The polycrystalline silicon product post-treatment process is the last processing process in the production of polycrystalline silicon, and the main production task is to process the polycrystalline silicon rod produced in the reduction furnace to generate a final product. The post-treatment process of the polycrystalline silicon product mainly comprises four aspects: crushing and packaging, silicon core processing, graphite piece processing and product detection. In the post-treatment process of the polysilicon product, a hydrofluoric acid and nitric acid mixture is used for pickling partial silicon blocks and processed silicon cores, the surfaces of which contain impurities, and cleaning the surface impurities on the silicon blocks and the silicon cores. Can produce a large amount of waste water that contains hydrofluoric acid and nitric acid in the cleaning process, this waste water has strong corrosivity, has provided higher requirement to the corrosion resistance of conveying equipment pipeline, leads to the equipment investment big, and contains a large amount of fluorinions in the waste water, and the emission of fluorine-containing waste water is great to the environmental impact.
At present, the methods for treating industrial fluorine-containing wastewater at home and abroad mainly comprise a precipitation method, an adsorption method, a freezing method, an ion exchange resin defluorination method, a liquid membrane method, a reverse osmosis method, an ultrafiltration defluorination method, an activated carbon defluorination method, an electrodialysis method, an electrocoagulation method, a co-distillation method and the like. The industrial treatment of strong acid waste water containing high content of fluorine mainly adopts precipitation method, uses lime milk to neutralize acidity of waste water, and adds PAC solution (polymerized Al)2O3Inorganic polymer coagulant) and PAM solution precipitation (polyacrylamide and nonionic polymer flocculant), and can realize better defluorination effect. TheThe process has the advantages of less dosage of medicament, simple method, convenient treatment, low cost and the like.
The cleaning of the silicon block and the silicon core is respectively carried out in a lump material cleaning machine and a silicon core cleaning machine, the processes of acid cleaning, water cleaning, drying and the like are respectively carried out in the cleaning machines, and waste acid discharged by the acid cleaning and acid-containing wastewater discharged by the water cleaning are mixed in the cleaning process and then sent to the fluorine-containing wastewater treatment process. In the cleaning process, waste acid and acid-containing wastewater are discharged intermittently, the concentration of hydrofluoric acid and nitric acid in the waste acid is high, the acid-containing wastewater only contains trace hydrofluoric acid and nitric acid, and the waste acid and the nitric acid are mixed to generate a large amount of acid wastewater, so that the treatment load of a downstream procedure is large, a large amount of alkali liquor is required to be added for neutralizing the acidity of the waste acid, the investment cost is high, and the environmental pollution is serious.
Therefore, the technology of pickling the waste acid obtained by acid washing and washing the acid-containing wastewater obtained by water washing of the existing lump material cleaning machine and/or silicon core cleaning machine needs to be further improved.
SUMMERY OF THE UTILITY MODEL
The present invention aims at solving at least one of the technical problems in the related art to a certain extent. To this end, it is an object of the present invention to provide a system for treating wastewater. By adopting the system, the treatment capacity of the pickling wastewater can be reduced by 60%, the water consumption can be saved by 50%, the consumption of new alkali can be reduced by 50%, and the system has excellent economic and environmental benefits.
In an aspect of the present invention, the utility model provides a system for treating wastewater, according to the embodiment of the utility model, this system includes:
the neutralization device is provided with a waste acid inlet, an alkali liquor inlet and a neutralized waste water outlet;
the first sedimentation device is provided with an acid-containing wastewater inlet, a neutralized wastewater inlet, a sedimentation agent inlet and a settled mixture outlet, and the neutralized wastewater inlet is connected with the neutralized wastewater outlet;
the filtering device is provided with a settled mixture inlet, a waste residue outlet and a waste liquid outlet, and the settled mixture inlet is connected with the settled mixture outlet;
a second settling device having a spent caustic inlet, a supernatant outlet, and a settled sludge outlet;
the mixing device is provided with a supernatant inlet, an alkali-containing wastewater inlet, a waste liquid inlet and an alkali liquor preparation outlet, wherein the supernatant inlet is connected with the supernatant outlet, the waste liquid inlet is connected with the waste liquid outlet, and the alkali liquor preparation outlet is connected with the alkali liquor inlet.
According to the utility model discloses system for handle waste water, through carrying out neutralization treatment with the waste acid that lump material cleaning machine and/or silicon core cleaning machine pickling gained earlier with alkali lye, mix the sour waste water that lump material cleaning machine and/or silicon core cleaning machine washing gained with waste water, the subside agent after neutralization again and subside, can show the waste acid volume that reduces neutralization treatment and the use amount of neutralization in-process alkali lye, can reduce the conveying capacity of acid waste water simultaneously, reduce the requirement to conveying equipment corrosion resistance; the supernatant is mixed with the alkali-containing wastewater and the waste liquid to prepare the alkali liquid, and the prepared alkali liquid is returned to be used as the alkali liquid, so that the waste liquid and the waste alkali can be recycled, the internal circulation of materials is realized, the discharge amount of the final waste liquid is reduced, the use amount of fresh water and fresh alkali in the process of preparing the alkali liquid can be obviously reduced, and the economic and environmental benefits of the process are improved. Therefore, by adopting the system, the treatment capacity of the pickling wastewater can be reduced by 60 percent, the water consumption can be saved by 50 percent, the consumption of the new alkali can be reduced by 50 percent, and the system has excellent economic and environmental benefits.
In addition, the system for treating wastewater according to the above embodiment of the present invention may further have the following additional technical features:
optionally, the neutralization device is a storage tank or tank with a stirrer.
Optionally, the first settling device and the second settling device are each independently a settling tank or a settling pond.
Optionally, the filtration device is a liquid-solid separation tank or a liquid-solid separation tank.
Optionally, the mixing device is a storage tank or tank with a stirrer.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a schematic diagram of a system for treating wastewater according to one embodiment of the present invention;
fig. 2 is a schematic flow diagram of a method for treating wastewater implemented by a system for treating wastewater according to an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary and intended to be used for explaining the present invention, and should not be construed as limiting the present invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," and "fixed" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.
In an aspect of the present invention, the present invention provides a system for treating wastewater, according to the embodiment of the present invention, referring to fig. 1, the system includes: a neutralization apparatus 100, a first settling apparatus 200, a filtering apparatus 300, a second settling apparatus 400, and a mixing apparatus 500.
According to the embodiment of the present invention, the neutralization device 100 has a waste acid inlet 101, an alkali solution inlet 102 and a neutralized waste water outlet 103, and is adapted to neutralize the waste acid obtained by acid washing of the lump material cleaning machine and/or the silicon core cleaning machine with the alkali solution so as to obtain neutralized waste water. Specifically, hydrogen ions in hydrofluoric acid and nitric acid in the waste acid and hydroxide ions in alkali liquor are subjected to chemical reaction to generate water, and the alkali liquor for treating the waste acid needs to be excessive in order to avoid too fast solution temperature rise in the neutralization treatment process due to large reaction heat of the neutralization reaction. It should be noted that the specific type of the neutralization device is not particularly limited, and can be selected by those skilled in the art according to actual needs, such as a storage tank or a storage tank with a stirrer. Furthermore, waste acid obtained by acid washing of the lump material cleaning machine and/or the silicon core cleaning machine can be added into alkali liquor for neutralization treatment, so as to obtain neutralized waste water. The inventor finds that the waste acid obtained by acid washing of the lump material cleaning machine and/or the silicon core cleaning machine is added into the alkali liquor for neutralization treatment, rather than adding the alkali liquor into the waste acid obtained by acid washing of the lump material cleaning machine and/or the silicon core cleaning machine, the phenomena that the waste acid is boiling when the alkali liquor is added, and the like, which cause harm to people and environment, can be avoided.
According to an embodiment of the utility model, the mass ratio of spent acid and alkali lye can be 1: 10-50, for example 1: 10/20/30/40/50. The inventor finds that if the mass ratio of the waste acid to the alkali liquor is too large, the content of the waste acid is high, and the solution temperature rises too fast in the neutralization process, so that the fuming phenomenon can occur; if the mass ratio of the waste acid to the alkali liquor is too small, the content of the alkali liquor is high, the waste of the alkali liquor is caused, and the production cost is increased. Further, the concentration of hydrofluoric acid in the waste acid may be 10 to 30 wt%, for example, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, and the concentration of nitric acid may be 30 to 60 wt%, for example, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%. The concentration of the lye may be 20-52.6 wt.%, for example 20 wt.%, 25 wt.%, 30 wt.%, 35 wt.%, 40 wt.%, 45 wt.%, 50 wt.%, 52.6 wt.%. The inventor finds that the concentration of the alkali liquor is too high, the water content in the solution is low, and the temperature of the solution rises too fast in the neutralization process; the concentration of the alkali liquor is too low, the water used for preparing the alkali liquor is increased, and waste is caused. Further, the alkali liquor is at least one selected from sodium hydroxide, potassium hydroxide and calcium hydroxide. When the alkali is neutralized with waste acid obtained by acid washing of a lump material cleaning machine and/or a silicon core cleaning machine, the reaction rate is high, and the neutralization effect is good.
According to the utility model discloses an embodiment, first subside device 200 has and contains acid waste water entry 201, neutralization back waste water entry 202, subsides agent entry 203 and subsides back mixture export 204, and neutralization back waste water entry 202 links to each other with neutralization back waste water export 103, and is suitable for the acid waste water that contains that lump material cleaning machine and/or silicon core cleaning machine washing gained with neutralization back waste water, subsides the agent mixture and subsides. Specifically, fluorine ions in the acid-containing wastewater and the neutralized wastewater can react with a settling agent to generate a fluorine-containing solid, and the fluorine-containing solid and the liquid can be separated after settling and filtering. The inventor finds that the waste acid obtained by acid washing of the lump material cleaning machine and/or the silicon core cleaning machine is neutralized with the alkali liquor, and then the acid-containing wastewater obtained by water washing of the lump material cleaning machine and/or the silicon core cleaning machine is mixed with the neutralized wastewater and the settling agent for settling, so that the waste acid amount of neutralization treatment and the use amount of the alkali liquor in the neutralization process can be remarkably reduced, the conveying amount of the acid wastewater can be reduced, and the requirement on the corrosion resistance of conveying equipment can be lowered. It should be noted that the specific type of the first settling device is not particularly limited, and those skilled in the art can select the first settling device according to actual needs, such as a settling tank or a settling tank. Further, the concentration of hydrofluoric acid in the acid-containing wastewater may be 0.1 to 0.3 wt%, for example, 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%, and the concentration of nitric acid may be 0.3 to 0.6 wt%, for example, 0.3 wt%, 0.35 wt%, 0.4 wt%, 0.45 wt%, 0.5 wt%, 0.55 wt%, 0.6 wt%. Further, the settling agent may be at least one selected from lime, PAM, PAC, and caustic soda. Further, the mass ratio of the acid-containing wastewater to the neutralized wastewater to the settling agent can be 100: 1000-2000: 1, for example, may be 100: 1000/1200/1400/1600/1800/2000: 1. the inventor finds that when the amount of the settling agent is less, fluorine ions in the acid-containing wastewater and the neutralized wastewater cannot be completely removed, so that the concentration of the fluorine ions in the wastewater is still high and the discharge requirement of the wastewater is not met; when the usage amount of the settling agent is large, the waste of the settling agent is caused, and the production cost is increased.
According to the utility model discloses an embodiment, filter equipment 300 has subsides back mixture entry 301, waste residue export 302 and waste liquid export 303, subsides back mixture entry 301 and subsides back mixture export 204 and link to each other, and is suitable for and subsides the liquid-solid mixture that the back gained with first device 200 of subsiding and filter, obtains waste residue and waste liquid. It should be noted that the specific type of the filtering device is not particularly limited, and those skilled in the art can select the filtering device according to actual needs, for example, the filtering device may be a liquid-solid separation tank or a liquid-solid separation tank.
According to the embodiment of the utility model, the second subsides device 400 has alkali waste entry 401, supernatant export 402 and subsides sediment export 403, and is suitable for and subsides the processing with alkali waste to obtain the supernatant and subside the sediment. Specifically, the waste alkali contains a small amount of silicon powder or other solid impurities, and after sedimentation and liquid-solid separation, the solid impurities in the waste alkali can be removed in the form of sedimentation slag to obtain a supernatant. It should be noted that the specific type of the second settling device is not particularly limited, and those skilled in the art can select the second settling device according to actual needs, such as a settling tank or a settling tank. Further, the concentration of the supernatant may be 35 to 45 wt%, and for example, may be 35 wt%, 37 wt%, 39 wt%, 41 wt%, 43 wt%, 45 wt%. Further, the supernatant may be at least one selected from the group consisting of a sodium hydroxide solution, a potassium hydroxide solution, and a calcium hydroxide solution. Further, the waste alkali can be obtained by alkali washing of a graphite piece cleaning machine. The inventor finds that the graphite part cleaning machine is required in the production process of polycrystalline silicon, waste liquid obtained by alkaline washing is used as waste alkali for sedimentation, obtained supernatant is used for subsequent preparation of alkali liquor, and obtained prepared alkali liquor is returned to a neutralization device to be used as the alkali liquor, so that the waste liquid obtained by alkaline washing of the graphite part cleaning machine can be recycled, the treatment cost of waste acid obtained by acid washing of the lump material cleaning machine and/or the silicon core cleaning machine is remarkably reduced, meanwhile, water consumption and new alkali consumption can be remarkably saved due to no need of new alkali, and economic and environmental benefits are remarkable.
According to the utility model discloses an embodiment, mixing arrangement 500 has supernatant entry 501, alkali-containing waste water entry 502, waste liquid entry 503 and configuration alkali lye export 504, and supernatant entry 501 links to each other with supernatant export 402, and waste liquid entry 503 links to each other with waste liquid export 303, and configuration alkali lye export 504 links to each other with alkali lye entry 102, and is suitable for to mix the supernatant with alkali-containing waste water, waste liquid to obtain configuration alkali lye, and will configure alkali lye to return to neutralization apparatus 100 and use as alkali lye. Specifically, the concentration of alkali in the supernatant is higher, and the alkali liquor meeting the requirement of the neutralization device can be obtained by mixing the supernatant with alkali-containing wastewater with lower alkali concentration and waste liquor close to neutrality and controlling the amount of each component in the mixing process according to the requirement of the neutralization device on the alkali concentration of the alkali liquor. The inventor finds that the supernatant is mixed with the alkali-containing wastewater and the waste liquid to prepare the alkali liquid, and the prepared alkali liquid is returned to be used as the alkali liquid, so that the waste liquid and the waste alkali can be recycled, the internal circulation of materials is realized, the discharge amount of the final waste liquid is reduced, the use amount of fresh water and fresh alkali in the process of preparing the alkali liquid can be obviously reduced, and the economic and environmental benefits of the process are improved. It should be noted that the specific type of the mixing device is not particularly limited, and those skilled in the art can select the mixing device according to actual needs, such as a tank or a storage tank with a stirrer.
According to an embodiment of the present invention, the concentration of the alkali-containing wastewater may be 0.1-10 wt%, for example, may be 0.1 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%. Further, the alkali-containing wastewater may be at least one selected from the group consisting of a sodium hydroxide solution, a potassium hydroxide solution, and a calcium hydroxide solution. Further, the alkali-containing wastewater can be obtained by washing the graphite piece cleaning machine with water. The inventor finds that the graphite part cleaning machine is required in the production process of polycrystalline silicon, waste liquid obtained by water washing is used as alkali-containing waste water for preparing alkali liquor, and the prepared alkali liquor is returned to the neutralization device to be used as the alkali liquor, so that the waste liquid obtained by water washing of the graphite part cleaning machine can be recycled, the treatment cost of waste acid obtained by acid washing of the lump material cleaning machine and/or the silicon core cleaning machine is remarkably reduced, and meanwhile, new alkali does not need to be prepared, so that the water consumption and the new alkali quantity can be further saved, and the economic and environmental benefits of the process are further improved. Further, the mass ratio of the supernatant to the alkali-containing wastewater to the waste liquid can be 1-50: 10-50: 1, for example, 1/10/20/30/40/50: 10/20/30/40/50: 1. the inventor finds that, because the supernatant liquid contains part of solid impurities, if the proportion of the supernatant liquid in the preparation of the alkali liquor is higher, the effect of the neutralization treatment of the prepared alkali liquor which is returned to be used as the alkali liquor is influenced; if the proportion of the supernatant liquid is low when the alkali liquor is prepared, the use amount of new alkali can be increased, and the production cost is increased.
According to the utility model discloses system for handle waste water, through carrying out neutralization treatment with the waste acid that lump material cleaning machine and/or silicon core cleaning machine pickling gained earlier with alkali lye, mix the sour waste water that lump material cleaning machine and/or silicon core cleaning machine washing gained with waste water, the subside agent after neutralization again and subside, can show the waste acid volume that reduces neutralization treatment and the use amount of neutralization in-process alkali lye, can reduce the conveying capacity of acid waste water simultaneously, reduce the requirement to conveying equipment corrosion resistance; the supernatant is mixed with the alkali-containing wastewater and the waste liquid to prepare the alkali liquid, and the prepared alkali liquid is returned to be used as the alkali liquid, so that the waste liquid and the waste alkali can be recycled, the internal circulation of materials is realized, the discharge amount of the final waste liquid is reduced, the use amount of fresh water and fresh alkali in the process of preparing the alkali liquid can be obviously reduced, and the economic and environmental benefits of the process are improved. Therefore, by adopting the system, the treatment capacity of the pickling wastewater can be reduced by 60 percent, the water consumption can be saved by 50 percent, the consumption of the new alkali can be reduced by 50 percent, and the system has excellent economic and environmental benefits.
For convenience of understanding, the following detailed description will be made of a method for treating wastewater performed by the above system for treating wastewater, which includes, according to an embodiment of the present invention, with reference to fig. 2:
s100: neutralizing waste acid obtained by acid washing of a lump material cleaning machine and/or a silicon core cleaning machine with alkali liquor
In the step, waste acid obtained by acid washing of the lump material cleaning machine and/or the silicon core cleaning machine is neutralized with alkali liquor so as to obtain neutralized waste water. Specifically, hydrogen ions in hydrofluoric acid and nitric acid in the waste acid and hydroxide ions in alkali liquor are subjected to chemical reaction to generate water, and the alkali liquor for treating the waste acid needs to be excessive in order to avoid too fast solution temperature rise in the neutralization treatment process due to large reaction heat of the neutralization reaction. Furthermore, waste acid obtained by acid washing of the lump material cleaning machine and/or the silicon core cleaning machine can be added into alkali liquor for neutralization treatment, so as to obtain neutralized waste water. The inventor finds that the waste acid obtained by acid washing of the lump material cleaning machine and/or the silicon core cleaning machine is added into the alkali liquor for neutralization treatment, rather than adding the alkali liquor into the waste acid obtained by acid washing of the lump material cleaning machine and/or the silicon core cleaning machine, the phenomena that the waste acid is boiling when the alkali liquor is added, and the like, which cause harm to people and environment, can be avoided.
According to an embodiment of the utility model, the mass ratio of spent acid and alkali lye can be 1: 10-50, for example 1: 10/20/30/40/50. The inventor finds that if the mass ratio of the waste acid to the alkali liquor is too large, the content of the waste acid is high, and the solution temperature rises too fast in the neutralization process, so that the fuming phenomenon can occur; if the mass ratio of the waste acid to the alkali liquor is too small, the content of the alkali liquor is high, the waste of the alkali liquor is caused, and the production cost is increased. Further, the concentration of hydrofluoric acid in the waste acid may be 10 to 30 wt%, for example, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, and the concentration of nitric acid may be 30 to 60 wt%, for example, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%. The concentration of the lye may be 20-52.6 wt.%, for example 20 wt.%, 25 wt.%, 30 wt.%, 35 wt.%, 40 wt.%, 45 wt.%, 50 wt.%, 52.6 wt.%. The inventor finds that the concentration of the alkali liquor is too high, the water content in the solution is low, and the temperature of the solution rises too fast in the neutralization process; the concentration of the alkali liquor is too low, the water used for preparing the alkali liquor is increased, and waste is caused. Further, the alkali liquor is at least one selected from sodium hydroxide, potassium hydroxide and calcium hydroxide. When the alkali is neutralized with waste acid obtained by acid washing of a lump material cleaning machine and/or a silicon core cleaning machine, the reaction rate is high, and the neutralization effect is good.
S200: mixing and settling acid-containing wastewater obtained by washing the lump material cleaning machine and/or the silicon core cleaning machine with neutralized wastewater and a settling agent
In the step, acid-containing wastewater obtained by washing the lump material cleaning machine and/or the silicon core cleaning machine with water is mixed with neutralized wastewater and a settling agent for settling, and waste residue and waste liquid are obtained after filtration. Specifically, fluorine ions in the acid-containing wastewater and the neutralized wastewater can react with a settling agent to generate a fluorine-containing solid, and the fluorine-containing solid and the liquid can be separated after settling and filtering. The inventor finds that the waste acid obtained by acid washing of the lump material cleaning machine and/or the silicon core cleaning machine is neutralized with the alkali liquor, and then the acid-containing wastewater obtained by water washing of the lump material cleaning machine and/or the silicon core cleaning machine is mixed with the neutralized wastewater and the settling agent for settling, so that the waste acid amount of neutralization treatment and the use amount of the alkali liquor in the neutralization process can be remarkably reduced, the conveying amount of the acid wastewater can be reduced, and the requirement on the corrosion resistance of conveying equipment can be lowered. Further, the concentration of hydrofluoric acid in the acid-containing wastewater may be 0.1 to 0.3 wt%, for example, 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%, and the concentration of nitric acid may be 0.3 to 0.6 wt%, for example, 0.3 wt%, 0.35 wt%, 0.4 wt%, 0.45 wt%, 0.5 wt%, 0.55 wt%, 0.6 wt%. Further, the settling agent may be at least one selected from lime, PAM, PAC, and caustic soda. Further, the mass ratio of the acid-containing wastewater to the neutralized wastewater to the settling agent can be 100: 1000-2000: 1, for example, may be 100: 1000/1200/1400/1600/1800/2000: 1. the inventor finds that when the amount of the settling agent is less, fluorine ions in the acid-containing wastewater and the neutralized wastewater cannot be completely removed, so that the concentration of the fluorine ions in the wastewater is still high and the discharge requirement of the wastewater is not met; when the usage amount of the settling agent is large, the waste of the settling agent is caused, and the production cost is increased.
S300: settling the waste alkali
In the step, the waste alkali is subjected to sedimentation treatment so as to obtain supernatant and sedimentation slag. Specifically, the waste alkali contains a small amount of silicon powder or other solid impurities, and after sedimentation and liquid-solid separation, the solid impurities in the waste alkali can be removed in the form of sedimentation slag to obtain a supernatant. Further, the concentration of the supernatant may be 35 to 45 wt%, and for example, may be 35 wt%, 37 wt%, 39 wt%, 41 wt%, 43 wt%, 45 wt%. Further, the supernatant may be at least one selected from the group consisting of a sodium hydroxide solution, a potassium hydroxide solution, and a calcium hydroxide solution. Further, the waste alkali can be obtained by alkali washing of a graphite piece cleaning machine. The inventor finds that the graphite part cleaning machine is required in the production process of polycrystalline silicon, waste liquid obtained by alkaline washing is used as waste alkali for settlement, obtained supernatant is used for subsequent preparation of alkali liquor, and obtained prepared alkali liquor is returned to S100 to be used as the alkali liquor, so that the waste liquid obtained by alkaline washing of the graphite part cleaning machine can be recycled, the treatment cost of waste acid obtained by acid washing of the lump material cleaning machine and/or the silicon core cleaning machine is remarkably reduced, meanwhile, due to the fact that no new alkali needs to be prepared, water consumption and new alkali consumption can be remarkably saved, and economic and environmental benefits are remarkable.
S400: mixing the supernatant with alkali-containing wastewater and waste liquid
In the step, the supernatant is mixed with the alkali-containing wastewater and the waste liquid so as to obtain the prepared alkali liquor, and the prepared alkali liquor is returned to S100 to be used as the alkali liquor. Specifically, the concentration of alkali in the supernatant is higher, and the alkali liquor meeting the requirement of S100 can be obtained by mixing the supernatant with alkali-containing wastewater with lower alkali concentration and waste liquor close to neutrality and controlling the amount of each component in the mixing process according to the requirement of the alkali liquor on the alkali concentration in S100. The inventor finds that the supernatant is mixed with the alkali-containing wastewater and the waste liquid to prepare the alkali liquid, and the prepared alkali liquid is returned to be used as the alkali liquid, so that the waste liquid and the waste alkali can be recycled, the internal circulation of materials is realized, the discharge amount of the final waste liquid is reduced, the use amount of fresh water and fresh alkali in the process of preparing the alkali liquid can be obviously reduced, and the economic and environmental benefits of the process are improved. Further, the concentration of the alkali-containing wastewater may be 0.1 to 10% by weight, and for example, may be 0.1%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% by weight. Further, the alkali-containing wastewater may be at least one selected from the group consisting of a sodium hydroxide solution, a potassium hydroxide solution, and a calcium hydroxide solution. Further, the alkali-containing wastewater can be obtained by washing the graphite piece cleaning machine with water. The inventor finds that the graphite part cleaning machine is required in the production process of polycrystalline silicon, waste liquid obtained by water washing is used as alkali-containing waste water for preparing alkali liquor, and the prepared alkali liquor is returned to S100 to be used as the alkali liquor, so that the waste liquid obtained by water washing of the graphite part cleaning machine can be recycled, the treatment cost of waste acid obtained by acid washing of the lump material cleaning machine and/or the silicon core cleaning machine is remarkably reduced, meanwhile, new alkali does not need to be prepared, the water consumption and the new alkali quantity can be further saved, and the economic and environmental benefits of the process are further improved. Further, the mass ratio of the supernatant to the alkali-containing wastewater to the waste liquid can be 1-50: 10-50: 1, for example, 1/10/20/30/40/50: 10/20/30/40/50: 1. the inventor finds that, because the supernatant liquid contains part of solid impurities, if the proportion of the supernatant liquid in the preparation of the alkali liquor is higher, the effect of the neutralization treatment of the prepared alkali liquor which is returned to be used as the alkali liquor is influenced; if the proportion of the supernatant liquid is low when the alkali liquor is prepared, the use amount of new alkali can be increased, and the production cost is increased.
According to the utility model discloses method for handle waste water, through carrying out neutralization treatment with the waste acid that lump material cleaning machine and/or silicon core cleaning machine pickling gained earlier with alkali lye, mix the waste acid that lump material cleaning machine and/or silicon core cleaning machine washing gained with waste water, the subside agent after neutralization again and subside, can show the waste acid volume that reduces neutralization treatment and the use amount of neutralization in-process alkali lye, can reduce the conveying capacity of acid waste water simultaneously, reduce the requirement to conveying equipment corrosion resistance; the supernatant is mixed with the alkali-containing wastewater and the waste liquid to prepare the alkali liquid, and the prepared alkali liquid is returned to be used as the alkali liquid, so that the waste liquid and the waste alkali can be recycled, the internal circulation of materials is realized, the discharge amount of the final waste liquid is reduced, the use amount of fresh water and fresh alkali in the process of preparing the alkali liquid can be obviously reduced, and the economic and environmental benefits of the process are improved. Therefore, by adopting the method, the treatment capacity of the pickling wastewater can be reduced by 60 percent, the water consumption can be saved by 50 percent, the consumption of the new alkali can be reduced by 50 percent, and the method has excellent economic and environmental benefits.
The invention will now be described with reference to specific examples, which are intended to be illustrative only and not to be limiting in any way.
Example 1
Adding waste acid obtained by acid washing of a lump material cleaning machine and/or a silicon core cleaning machine into alkali liquor for neutralization treatment, wherein the mass ratio of the waste acid to the alkali liquor is 1: 100, the concentration of hydrofluoric acid in the waste acid is 10 wt%, and the concentration of nitric acid is 30 wt%. The alkali liquor is a sodium hydroxide solution with the concentration of 20 wt%, and neutralized wastewater is obtained; mixing and settling acid-containing wastewater obtained by washing the lump material cleaning machine and/or the silicon core cleaning machine with neutralized wastewater and a settling agent lime, wherein the concentration of hydrofluoric acid in the acid-containing wastewater is 0.3 wt%, the concentration of nitric acid is 0.3 wt%, and the mass ratio of the acid-containing wastewater to the neutralized wastewater and the settling agent is 100: 1000: 1, filtering to obtain waste residues and waste liquid; carrying out sedimentation treatment on waste alkali obtained by alkaline washing of a graphite piece cleaning machine to obtain supernatant sodium hydroxide solution with the concentration of 35 wt% and sedimentation slag; washing the supernatant with a graphite piece cleaning machine to obtain an alkali-containing wastewater sodium hydroxide solution with the concentration of 0.1 wt%, and mixing the obtained alkali-containing wastewater sodium hydroxide solution with the waste liquid according to the mass ratio of 1: 50: 1, mixing to obtain prepared alkali liquor, and returning the prepared alkali liquor to be used as the alkali liquor. The whole process can reduce the treatment capacity of the acidic wastewater by 60 percent, save the water consumption by 50 percent, reduce the new alkali by 50 percent, and have good economic and environmental protection benefits.
Example 2
Adding waste acid obtained by acid washing of a lump material cleaning machine and/or a silicon core cleaning machine into alkali liquor for neutralization treatment, wherein the mass ratio of the waste acid to the alkali liquor is 1: 30, the concentration of hydrofluoric acid in the waste acid is 20 wt%, and the concentration of nitric acid is 50 wt%. The alkali liquor is 35 wt% potassium hydroxide solution to obtain neutralized wastewater; mixing and settling acid-containing wastewater obtained by washing a lump material cleaning machine and/or a silicon core cleaning machine with neutralized wastewater and a settling agent PAM, wherein the concentration of hydrofluoric acid in the acid-containing wastewater is 0.1 wt%, the concentration of nitric acid is 0.5 wt%, and the mass ratio of the acid-containing wastewater to the neutralized wastewater and the settling agent is 100: 1500: 1, filtering to obtain waste residues and waste liquid; carrying out sedimentation treatment on waste alkali obtained by alkaline washing of a graphite piece cleaning machine to obtain supernatant potassium hydroxide solution with the concentration of 40 wt% and sedimentation slag; washing the supernatant with a graphite piece cleaning machine to obtain an alkali-containing wastewater potassium hydroxide solution with the concentration of 0.5 wt%, and mixing the obtained alkali-containing wastewater potassium hydroxide solution with the waste liquid according to the mass ratio of 25: 30: 1, mixing to obtain prepared alkali liquor, and returning the prepared alkali liquor to be used as the alkali liquor. The whole process can reduce the treatment capacity of the acid wastewater by 50 percent, save the water consumption by 45 percent, reduce the new alkali by 45 percent, and has good economic and environmental protection benefits.
Example 3
Adding waste acid obtained by acid washing of a lump material cleaning machine and/or a silicon core cleaning machine into alkali liquor for neutralization treatment, wherein the mass ratio of the waste acid to the alkali liquor is 1: 50, the concentration of hydrofluoric acid in the waste acid is 30 wt%, and the concentration of nitric acid is 60 wt%. The alkali liquor is calcium hydroxide solution with the concentration of 52.6 wt%, and neutralized waste water is obtained; mixing and settling acid-containing wastewater obtained by washing the lump material cleaning machine and/or the silicon core cleaning machine with neutralized wastewater and a settling agent PAC, wherein the concentration of hydrofluoric acid in the acid-containing wastewater is 0.15 wt%, the concentration of nitric acid is 0.6 wt%, and the mass ratio of the acid-containing wastewater to the neutralized wastewater and the settling agent is 100: 2000: 1, filtering to obtain waste residues and waste liquid; carrying out sedimentation treatment on waste alkali obtained by alkaline washing of a graphite piece cleaning machine to obtain a supernatant calcium hydroxide solution with the concentration of 45 wt% and sedimentation slag; washing the supernatant with a graphite piece cleaning machine to obtain an alkali-containing wastewater calcium hydroxide solution with the concentration of 0.1 wt%, and mixing the alkali-containing wastewater calcium hydroxide solution with the waste liquid according to the mass ratio of 50: 10: 1. mixing to obtain prepared alkali liquor, and returning the prepared alkali liquor to be used as the alkali liquor. The whole process can reduce the treatment capacity of the acidic wastewater by 40 percent, save the water consumption by 40 percent, reduce the new alkali by 40 percent, and have good economic and environmental protection benefits.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art without departing from the scope of the present invention.
Claims (5)
1. A system for treating wastewater, comprising:
the neutralization device is provided with a waste acid inlet, an alkali liquor inlet and a neutralized waste water outlet;
the first sedimentation device is provided with an acid-containing wastewater inlet, a neutralized wastewater inlet, a sedimentation agent inlet and a settled mixture outlet, and the neutralized wastewater inlet is connected with the neutralized wastewater outlet;
the filtering device is provided with a settled mixture inlet, a waste residue outlet and a waste liquid outlet, and the settled mixture inlet is connected with the settled mixture outlet;
a second settling device having a spent caustic inlet, a supernatant outlet, and a settled sludge outlet;
the mixing device is provided with a supernatant inlet, an alkali-containing wastewater inlet, a waste liquid inlet and an alkali liquor preparation outlet, wherein the supernatant inlet is connected with the supernatant outlet, the waste liquid inlet is connected with the waste liquid outlet, and the alkali liquor preparation outlet is connected with the alkali liquor inlet.
2. The system of claim 1, wherein the neutralization device is a tank or reservoir with an agitator.
3. The system of claim 1 or 2, wherein the first settling device and the second settling device are each independently a settling tank or a settling pond.
4. The system of claim 1, wherein the filtration device is a liquid-solid separation cell or a liquid-solid separation tank.
5. The system of claim 1, wherein the mixing device is a tank or reservoir with a stirrer.
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| CN110078261A (en) * | 2019-05-20 | 2019-08-02 | 中国恩菲工程技术有限公司 | Handle the method and system of waste water |
| CN110078261B (en) * | 2019-05-20 | 2024-02-09 | 中国恩菲工程技术有限公司 | Method and system for treating wastewater |
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