A method for treating high-salt wastewater

Abstract

The invention relates to the technical field of wastewater treatment, and in particular to a method for treating high-salt wastewater, comprising the following steps: S1, evaporating wastewater to obtain a first waste salt and a mother liquor; S2, performing primary carbonization treatment on the mother liquor to obtain a second waste salt; S3, performing secondary carbonization treatment on the first waste salt and / or the second waste salt to obtain a carbonized salt; S4, separating the carbonized salt to obtain a carbide and a salt that can be recycled; it can be seen that this scheme can not only treat the salt content of high-salt wastewater, but also, through the carbonization treatment step, can carbonize organic matter in the salt to obtain a carbide that can be used as a fuel, and finally obtain salt that can be suitable for industrial use; in this way, the salt content of high-salt wastewater is treated, and the salt and the carbide are recovered, so as to achieve the recycling and utilization of resources.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a method for treating high-salt wastewater. Background Art

[0002] Many chemical plants now have high-salt wastewater, which is generally treated to a COD concentration of 300mg / L-500mg / L and then discharged directly to an urban sewage treatment plant, where it is then treated until it meets discharge standards.

[0003] However, there are two problems: 1. Although COD can be reduced after chemical wastewater treatment, the salt content cannot be reduced. When the salt-containing wastewater is directly discharged into the urban sewage treatment plant, it is easy to impact the biochemical system in the urban sewage treatment plant, thereby causing the system collapse of the downstream sewage treatment plant; 2. Urban sewage treatment plants can reduce COD, but cannot remove salt. Direct discharge into rivers will also cause irreversible damage to the environment.

[0004] Therefore, it is necessary to design a treatment method that can target high-concentration, high-salt wastewater.

[0005] in:

[0006] High-salinity wastewater refers to wastewater with a salt content of more than 1.5%;

[0007] High-concentration wastewater refers to wastewater with a COD concentration above 2000 mg / L. Summary of the invention

[0008] In order to solve at least one of the technical problems mentioned in the background technology, the object of the present invention is to provide a method for treating high-salt wastewater.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] A method for treating high-salt wastewater comprises the following steps:

[0011] S1, evaporating the wastewater to obtain first waste salt and mother liquor;

[0012] S2, performing primary carbonization treatment on the mother liquor to obtain a second waste salt;

[0013] S3, performing secondary carbonization treatment on the first waste salt and / or the second waste salt to obtain carbonized salt;

[0014] S4. Separating the carbonized salt to obtain carbide and recyclable salt.

[0015] As an optional implementation manner of the present invention, the following steps are also included before step S1:

[0016] S01. Determine the salt concentration of the wastewater;

[0017] If the salt concentration of the wastewater is greater than 10%, directly proceed to step S1;

[0018] If the salt concentration of the wastewater is between 5% and 10%, proceed to step S02;

[0019] If the salt concentration of the wastewater is between 3% and 5%, directly proceed to step S03;

[0020] S02, mixing the wastewater to obtain wastewater with a salt concentration of 3%-5%, and then proceeding to step S03;

[0021] S03, biochemically treating the wastewater to reduce the COD concentration in the wastewater, and then entering step S04;

[0022] S04, concentrate the wastewater to obtain wastewater with a salt concentration greater than 10%, and then enter step S1.

[0023] As an optional embodiment of the present invention, in step S03, the wastewater is biochemically treated by using salt-tolerant bacteria; and / or in step S03, the COD concentration in the wastewater is reduced to 300 mg / L-500 mg / L by using biochemical treatment.

[0024] As an optional implementation of the present invention, in step S04, the wastewater is concentrated by using a reverse osmosis method or an electrodialysis method.

[0025] As an optional embodiment of the present invention, in step S02, wastewater is mixed with fresh water to obtain wastewater with a salt concentration of 3%-5%.

[0026] As an optional embodiment of the present invention, in step S2, the mother liquor is subjected to primary carbonization treatment by a mother liquor carbonization treatment device;

[0027] The mother liquor carbonization treatment device includes a first heating furnace, a liquid spraying mechanism and a scraper; a material receiving surface is provided at the bottom of the first heating furnace, and the material receiving surface is inclined to form a high end and a low end; a liquid inlet area for storing mother liquor is formed on the lower end side of the material receiving surface inside the first heating furnace; the liquid spraying mechanism includes a pump and a plurality of nozzles, and the pump is used to extract the mother liquor from the liquid inlet area to the nozzle, and the nozzle sprays the mother liquor in the first heating furnace; the scraper is arranged in the first heating furnace, and can fit the material receiving surface to scrape the waste salt falling on the material receiving surface from the lower end to the high end of the inclined surface.

[0028] As an optional embodiment of the present invention, in step S3, the secondary carbonization treatment of the waste salt is carried out using a hazardous waste salt carbonization treatment device;

[0029] The hazardous waste salt carbonization treatment device includes a second heating furnace, a material bed for placing waste salt and extending along a first direction is provided in the second heating furnace, a rotating shaft is rotatably arranged and extends along the first direction above the material bed in the second heating furnace, and the rotation axis of the rotating shaft is parallel to the first direction; the interior of the rotating shaft is hollow to form a channel for steam to pass through; a plurality of flipping members distributed in sequence along the first direction are fixedly connected to the rotating shaft; the flipping member has a cavity connected to the channel; the flipping member flips under the drive of the rotating shaft to contact and flip the waste salt on the material bed.

[0030] As an optional embodiment of the present invention, the material bed can reciprocate along the first direction in the second heating furnace.

[0031] As an optional embodiment of the present invention, in step S4, separating the carbonized salt comprises the following steps:

[0032] S41, dissolving the carbonized salt using water to obtain a waste salt solution;

[0033] S42, filtering, filtering the waste salt solution to achieve solid-liquid separation, and obtaining carbide and brine respectively;

[0034] S43, evaporation and crystallization, evaporating and crystallizing the salt water to obtain salt that can be recycled;

[0035] S44, screening and salt separation, screening the salt obtained in step S43 to obtain coarse salt and fine salt respectively.

[0036] As an optional embodiment of the present invention, before performing secondary carbonization treatment on the first waste salt and / or the second waste salt in step S3, the first waste salt and / or the second waste salt is preliminarily screened.

[0037] Compared with the prior art, the advantages of adopting this solution are:

[0038] The treatment method provided by the present invention can effectively treat high-salt wastewater. The mother liquor can be carbonized through the primary carbonization treatment to form the second waste salt. Then, the first waste salt and the second waste salt can be carbonized through the secondary carbonization treatment to form carbonized salt. Finally, the carbonized salt is separated to obtain carbide and recyclable salt. The carbide itself has a certain calorific value and can be used as fuel. The salt can be used to meet the salt needs of some factories to achieve recycling.

[0039] In summary, it can be seen that this scheme can not only treat the salt content of high-salt wastewater, but also, through the carbonization treatment step, can carbonize the organic matter in the salt to obtain carbides that can be used as fuel, and finally obtain salt that can be suitable for industrial use; in this way, the salt content of high-salt wastewater is treated, and salt and carbides are recovered, thereby achieving the recycling of resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a process flow chart of the present invention;

[0041] Figure 2 It is a front cross-sectional view of the mother liquid carbonization treatment device of the present invention;

[0042] Figure 3 It is a top cross-sectional view of the mother liquid carbonization treatment device of the present invention;

[0043] Figure 4 for Figure 3 A partial enlarged view of the middle nozzle position;

[0044] Figure 5 It is a radial cross-sectional view of the mother liquid carbonization treatment device of the present invention;

[0045] Figure 6 It is a front cross-sectional view of the hazardous waste salt carbonization treatment device of the present invention;

[0046] Figure 7 It is a radial cross-sectional view of the hazardous waste salt carbonization treatment device of the present invention;

[0047] Figure 8 for Figure 6 A partial enlargement of the blade location. DETAILED DESCRIPTION

[0048] The technical solutions of the embodiments of the present invention are explained and described below in conjunction with the drawings of the embodiments of the present invention, but the following embodiments are only preferred embodiments of the present invention, not all. Based on the embodiments in the implementation mode, other embodiments obtained by those skilled in the art without creative work are all within the protection scope of the present invention.

[0049] In the following description, terms such as "inside", "outside", "up", "down", "left", "right", etc. that indicate directions or positional relationships are only used to facilitate the description of the embodiments and simplify the description, and do not indicate or imply that the referred device or element must have a specific direction, be constructed and operate in a specific direction. Therefore, they should not be understood as limitations on the present invention.

[0050] See also Figure 1-8As shown, this embodiment provides a high-salt wastewater treatment method, which can be particularly used for the treatment of high-concentration, high-salt wastewater; high-salt wastewater refers to wastewater with a salt content of more than 1.5%; high-concentration wastewater refers to wastewater with a COD concentration of more than 2000 mg / L.

[0051] The high-salt wastewater treatment method provided by the present invention comprises the following steps:

[0052] S1, evaporating the wastewater to obtain first waste salt and mother liquor;

[0053] S2, performing primary carbonization treatment on the mother liquor to obtain a second waste salt;

[0054] S3, performing secondary carbonization treatment on the first waste salt and / or the second waste salt to obtain carbonized salt;

[0055] S4. Separating the carbonized salt to obtain carbide and recyclable salt.

[0056] Example 1

[0057] This embodiment provides a method for treating high-salt wastewater, comprising the following steps:

[0058] S01. Determine the salt concentration of the wastewater;

[0059] If the salt concentration of the wastewater is greater than 10%, directly proceed to step S1;

[0060] If the salt concentration of the wastewater is between 5% and 10%, proceed to step S02;

[0061] If the salt concentration of the wastewater is between 3% and 5%, directly proceed to step S03.

[0062] S02, mixing the wastewater to obtain wastewater with a salt concentration of 3%-5%, and then entering step S03.

[0063] In step S02, wastewater is mixed with fresh water to obtain wastewater with a salt concentration of 3%-5%; the fresh water here can be domestic sewage, as well as production and cleaning wastewater with low salt content.

[0064] S03, biochemically treating the wastewater to reduce the COD concentration in the wastewater, preferably reducing the COD concentration in the wastewater to 300mg / L-500mg / L; then entering step S04; the biochemical treatment step here can specifically be to use salt-tolerant bacteria to biochemically treat the wastewater to reduce the COD concentration in the wastewater.

[0065] The purpose of biochemical treatment here is that the waste liquid needs to be concentrated in step S04. Generally, membranes are used for concentration. If there are too many organic substances in the sewage, the membrane will be damaged and the service life of the membrane will be greatly shortened. Therefore, the waste water needs to be biochemically treated to reduce the COD concentration in the waste water.

[0066] The reason why biochemical treatment is used to treat COD instead of other methods such as chemicals is that, first, biochemical treatment is cheap; second, the waste liquid treated by biochemical treatment will cause less damage to the concentration membrane during subsequent concentration, which is beneficial to protecting the membrane.

[0067] S04, concentrate the wastewater to obtain wastewater with a salt concentration greater than 10%, and then enter step S1.

[0068] In step S04, the wastewater is concentrated by using reverse osmosis or electrodialysis.

[0069] Reverse osmosis is a mature technology that can concentrate 3-5% salt water into 10% concentrated water and 1% fresh water. The price is about 1 yuan per ton for every 1% of concentration. The service life of the membrane is generally 3 years, and the membrane flux basically decreases at a rate of 20% per year.

[0070] Electrodialysis is commonly used in seawater desalination technology. It can concentrate 3%-5% salt water into 15% concentrated water and 1% fresh water. Within 10%, the price is about 1 yuan / ton for each 1% of concentration. For concentrations above 10%, the cost increases accordingly as the concentration increases. Generally, it is appropriate to concentrate to 14%.

[0071] The above two concentration methods each have their own advantages and disadvantages, and can be selected and used according to actual needs.

[0072] S1. Evaporation treatment of wastewater. During the evaporation of wastewater, three substances will be produced: distilled water, which can be treated in a sewage treatment pool; waste salt (recorded as the first waste salt for distinction); and mother liquor, which is wastewater with high COD concentration and saturated salt concentration. The purpose of this step is to obtain the first waste salt and mother liquor. The first waste salt here is mainly hazardous waste salt containing organic matter.

[0073] In step S01, the commonly used evaporators are single-effect, triple-effect, five-effect evaporators and MVR evaporators. It is generally believed that a single-effect evaporator requires 0.8 tons of steam to evaporate one ton of water, a triple-effect evaporator requires 0.4 tons of steam to evaporate one ton of water, a five-effect evaporator requires 0.25 tons of steam to evaporate one ton of water, and an MVR evaporator requires 0.17 tons of steam to evaporate one ton of water. The energy used by the MVR evaporator is mainly electricity. Considering the comprehensive cost, a five-effect evaporator can be selected here.

[0074] It is worth mentioning that the reason why the wastewater is concentrated to obtain wastewater with a salt concentration of more than 10% and then enters step S1 for evaporation is that if the wastewater containing 3-5% salt is directly evaporated, the energy consumption is too large, so it is necessary to concentrate it to a salt content of more than 10%; preferably, it is concentrated to a salt content of 13-15%; and then evaporated.

[0075] This is why in step S01, different treatment methods are used according to the different salt concentrations of the wastewater before evaporation. Specifically:

[0076] Since direct evaporation of wastewater with a salt concentration of 5%-10% or 3%-5% consumes too much energy, it needs to be concentrated before evaporation to make the salt concentration greater than 10% before entering step S1 for evaporation to reduce energy consumption during evaporation.

[0077] Membranes are generally required for concentration. If the COD concentration or organic matter content in the wastewater is too high, direct concentration will easily damage the membrane and be detrimental to the service life of the membrane. Therefore, the wastewater needs to be biochemically treated before concentration to reduce the COD concentration in the wastewater to 300mg / L-500mg / L.

[0078] Before biochemical treatment, if the salt concentration in the wastewater is high, it is not conducive to the biochemical treatment of salt-tolerant bacteria. Therefore, for wastewater with a salt concentration of 5%-10%, before biochemical treatment, it must be mixed and treated to reduce the salt concentration to 3%-5% before concentration.

[0079] S2, the mother liquor is subjected to primary carbonization treatment to obtain the second waste salt, and then the process proceeds to step S3, wherein the primary carbonization treatment step may adopt the mother liquor carbonization treatment device provided in Example 2, and reference may be made to the description of Example 2. The second waste salt here is mainly waste salt containing organic matter, generally mainly a mixture of carbide and waste salt, which is equivalent to hazardous waste salt that has been carbonized to a certain extent.

[0080] S3, performing secondary carbonization treatment on the first waste salt and / or the second waste salt to obtain carbonized salt, and then proceeding to step S4. The secondary carbonization treatment here can be performed using the hazardous waste salt carbonization treatment device provided in Example 3, and the description of Example 3 can be referred to.

[0081] It can be understood that in step S3, it is preferred that both the first waste salt and the second waste salt are subjected to secondary carbonization treatment, and they can be subjected to secondary carbonization separately, or they can be mixed and subjected to secondary carbonization together, so that the organic matter in the first waste salt and the second waste salt is fully carbonized to form carbide, and finally a carbonized salt, that is, a mixture of carbide and waste salt, is obtained.

[0082] S4, separating and treating the carbide salt to obtain carbide and recyclable salt, which can be used as industrial salt. The separation treatment specifically includes the following steps:

[0083] S41. Dissolving the carbonized salt with water to obtain a waste salt solution. Specifically: according to the property that carbide is insoluble in water and salt is soluble in water, the carbonized salt is put into water to dissolve and obtain the waste salt solution.

[0084] S42, filtration. Since salt is soluble in water, but carbide is not soluble in water, solid-liquid separation can be achieved by filtering the waste salt solution obtained in S41, and water-insoluble carbide and salt water containing dissolved salt can be obtained respectively. The obtained carbide has a certain calorific value and can be used as coal powder for incineration later.

[0085] In step S42, the specific filtering process may be to use a centrifuge (rotating speed of 4000 r / min) and a layer of filter cloth to separate the waste salt solution into solid and liquid to obtain carbide and nearly saturated brine.

[0086] The brine obtained in step S42 enters step S43 for processing.

[0087] S43, evaporation and crystallization, evaporation and crystallization of nearly saturated salt water to obtain salt that can be recycled; and the distilled water produced by evaporation can be used as irrigation water, cooling water, circulating water, production water, etc. according to actual needs. The salt obtained in step S43 enters step S44 for processing.

[0088] S44, screening and separating the salt, screening the salt obtained in step S43 to obtain coarse salt and fine salt respectively; this part of coarse salt and fine salt can be used for the salt needs of some printing and dyeing factories, chemical plants and other enterprises, and can be used comprehensively to achieve the recycling of resources.

[0089] In step S44, specifically, the salt obtained in step S44 can be screened using a sieve having a pore size to obtain coarse salt and fine salt, so as to be classified and used as industrial salt.

[0090] In addition, before the first waste salt and / or the second waste salt are subjected to secondary carbonization treatment in step S3, the first waste salt and / or the second waste salt are preliminarily screened. The consideration is that since a large part of the hazardous waste salt (i.e., the first waste salt and the second waste salt) is obtained through evaporation, it is very easy to agglomerate. Therefore, a vibrating screen can be used to preliminarily screen the hazardous waste salt, which can effectively prevent the agglomerated salt from entering the device, thereby more effectively utilizing heat energy and reducing operating costs.

[0091] Example 2

[0092] like Figure 2-5As shown, this embodiment provides a mother liquor carbonization treatment device, which can be used to perform primary carbonization treatment on the mother liquor in step S2 of embodiment 1.

[0093] The mother liquid carbonization treatment device provided in this embodiment includes a first heating furnace 1 , a liquid spraying mechanism and a scraper 6 .

[0094] The first heating furnace 1 is mainly used for heating the mother liquor, which can be heated by steam or by electric heating.

[0095] In some embodiments, Figure 2 As shown, the first heating furnace 1 mainly includes a first inner shell 12, a first outer shell 11 inserted into the outside of the first inner shell 12, and a first end plate 13 arranged at both ends of the first inner shell 12 and the first outer shell 11; the first inner shell 12 and the first outer shell 11 as a whole constitute the surrounding wall of the first heating furnace 1, and the first end plates 13 at both ends constitute the end walls of the first heating furnace 1.

[0096] The first inner shell 12 and the first outer shell 11 are spaced apart to form a first interlayer space 10; Figure 5 As shown, the first inner shell 12 and the first outer shell 11 are both cylindrical structures and are coaxially arranged.

[0097] The first heating furnace 1 is heated by introducing steam into the first interlayer space 10 or by providing an electric heating element in the first interlayer space 10 .

[0098] Take steam heating as an example: Figure 2 As shown, a first steam inlet 132 is provided on the first end plate 13 or the first outer shell 11 for connecting to an external steam pipeline. The steam output from the steam pipeline enters the first interlayer space 10 through the first steam inlet 132 to heat the first inner shell 12, thereby achieving heating inside the first heating furnace 1.

[0099] It is worth noting that, during heating, the temperature in the furnace is preferably set between 550°C and 650°C.

[0100] In addition, during the carbonization treatment of the mother liquor in the first heating furnace 1, it is preferred to introduce a substance that blocks oxygen from entering the furnace, such as nitrogen or hot steam, into the furnace to reduce the generation of dioxins during the carbonization process.

[0101] In some embodiments, Figure 2 As shown, in order to discharge the condensed water generated by the condensation of steam in the first interlayer space 10 later, a first condensed water outlet 111 is provided at the bottom of the first outer shell 11. In order to control the opening and closing of the first condensed water outlet 111, the first condensed water outlet 111 can be connected to a valve.

[0102] In addition, in some embodiments, Figure 2 As shown, a mother liquid inlet 131 is provided on the first end plate 13 , and the mother liquid inlet 131 is mainly used to connect to a mother liquid input pipeline, and the mother liquid enters the first heating furnace 1 through the mother liquid input pipeline via the mother liquid inlet 131 .

[0103] A material receiving surface 31 is provided at the bottom of the first heating furnace 1, and the material receiving surface 31 is inclined so that one end of the material receiving surface 31 is high and the other end is low. For the convenience of explanation, the high end of the material receiving surface 31 is recorded as the high end 3b, and the low end is recorded as the low end 3a.

[0104] In some embodiments, a slope plate 3 is provided at the bottom of the first heating furnace 1 , and the top surface of the slope plate 3 constitutes the material receiving surface 31 .

[0105] In other embodiments, the inner side surface of the inner bottom wall of the first heating furnace 1 constitutes the material receiving surface 31 , for example, a portion of the inner side surface of the inner bottom wall of the first heating furnace 1 that is inclined upward and protrudes serves as the material receiving surface 31 .

[0106] A liquid inlet area 4 for storing mother liquor is formed inside the first heating furnace 1 on one side of the lower end 3a of the material receiving surface 31; specifically, the lower end 3a of the material receiving surface 31 is connected to the bottom wall of the first inner shell 12 via an inclined transition plate 32, and the liquid inlet area 4 is formed between the transition plate 32 and the first end plate 13 on the right side, wherein the bottom surface of the liquid inlet area 4 is lower than the lower end 3a of the material receiving surface 31, which is equivalent to having a concave area on one side of the lower end 3a of the material receiving surface 31, serving as the liquid inlet area 4 for storing mother liquor to be carbonized.

[0107] The liquid spraying mechanism includes a pump 21 and a plurality of nozzles 23. The pump 21 is arranged in the liquid inlet area 4 and is used to extract the mother liquid in the liquid inlet area 4 to the nozzles 23, and then the nozzles 23 spray the mother liquid into the first heating furnace 1.

[0108] The specific connection between the nozzle 23 and the pump 21 is: a liquid inlet pipe 22 is connected to the liquid outlet end of the pump 21, and the end of the liquid inlet pipe 22 away from the pump 21 is closed; the liquid inlet pipe 22 at least partially extends along the length direction of the first heating furnace 1 (that is, the axial direction of the first heating furnace 1) to form an extension section 221, and each of the nozzles 23 is arranged in sequence on the extension section 221 along the length direction of the extension section 221.

[0109] During operation, the first heating furnace 1 is heated, and the pump 21 extracts the mother liquor in the liquid inlet area 4. The extracted mother liquor flows to the nozzle 23 through the liquid inlet pipe 22 and is finally ejected from the nozzle 23. The ejected mother liquor is dispersed in the first heating furnace 1 and is heated and carbonized. Mainly, the organic matter in the mother liquor is carbonized to finally form carbonized salt. The carbonized salt refers to a mixture of carbide and waste salt, that is, the second waste salt mentioned in Example 1; in this way, the mother liquor is treated.

[0110] The second waste salt obtained here is generally still a carbonized salt that is not fully carbonized. Therefore, it can be subsequently subjected to secondary carbonization treatment through the hazardous waste salt carbonization treatment device provided in Example 3 to fully carbonize the second waste salt into carbonized salt.

[0111] This spraying method of the nozzle 23 spraying the mother liquid for heating can increase the dispersion range of the mother liquid and improve the thermal efficiency.

[0112] The carbonized salt produced by the mother liquor during the carbonization process and the mother liquor dripping from the nozzle 23 will fall onto the material receiving surface 31; since the material receiving surface 31 is inclined, the mother liquor on the material receiving surface 31 returns to the liquid inlet area 4 along the material receiving surface 31 and is extracted and ejected again by the pump 21, so that the mother liquor in the first heating furnace 1 can be circulated, extracted and ejected, which is beneficial to the sufficient carbonization of the mother liquor.

[0113] The scraper 6 is arranged in the first heating furnace 1 and can be in contact with the material receiving surface 31 to scrape the waste salt falling on the material receiving surface 31 from the lower end 3a of the inclined surface to the higher end 3b.

[0114] In this way, by scraping with the scraper 6 , it can be avoided to a large extent that the mother liquid on the material receiving surface 31 will not bring the carbonized salts falling on the material receiving surface 31 back to the liquid inlet area 4 during the reflux process.

[0115] Furthermore, by providing the scraper 6, the carbides and waste salts dropped on the receiving surface 31 can be scraped toward the high end 3b of the receiving surface 31, so that the carbides and waste salts can be gathered together for easy unified collection later.

[0116] In some embodiments, Figure 2 As shown, a concave area is formed on one side of the high end 3 b of the material receiving surface 31 as a material receiving groove 33 , and the carbonized salt on the material receiving surface 31 is finally scraped off by the scraper 6 into the material receiving groove 33 .

[0117] Of course, in other embodiments, the material receiving groove 33 may not be provided, and the scraper 6 only needs to scrape the carbonized salt on the material receiving surface 31 directly to the high end 3 b of the material receiving surface 31 .

[0118] like Figure 5 As shown, the cross section of the material receiving surface 31 in the radial direction of the first heating furnace 1 is a concave arc structure, and the corresponding scraper 6 is also called an arc structure to adapt to the material receiving surface 31.

[0119] The scraper 6 can be a scraper or a scraper net. The scraper net here refers to a mesh scraper, and preferably a scraper net. During the scraping process, the mother liquor can flow back into the liquid inlet area 4 through the mesh holes of the scraper net, while the carbonized salt is scraped to the high end 3b of the material receiving surface 31.

[0120] In some embodiments, the spray head 23 can rotate around a first axis when spraying liquid, wherein the first axis is vertically perpendicular to the axial direction of the first heating furnace 1; specifically:

[0121] The spray head 23 is rotatably mounted on the liquid inlet pipe 22 around a first axis.

[0122] Combination Figure 2 and Figure 4 As shown, the nozzle 23 includes a straight pipe section 232, which is rotatably connected to the extension section 221 around the first axis and communicates with the extension section 221; at least two nozzles 231 are provided at the upper end of the straight pipe section 232, and the at least two nozzles 231 are distributed in a circular array with the first axis as the center.

[0123] The spraying direction of the nozzle 231 is horizontal, and the extension line of the spraying direction of the nozzle 231 deviates from the first axis. Figure 4 For example, one of the nozzles sprays liquid to the left, and the other sprays liquid to the right. When the nozzle sprays the mother liquid, the mother liquid enters the straight pipe section 232 from the liquid inlet pipe 22, and then flows from the straight pipe section 232 to each nozzle 231. Since the extension line of the spraying direction of each nozzle 231 deviates from the first axis, when the nozzle 231 sprays the mother liquid, a recoil force is generated, thereby pushing the straight pipe section 232 to rotate around the first axis, and then driving the entire nozzle 23 to rotate around the first axis on the extension section 221 to spray liquid.

[0124] The significance of driving the nozzle 23 to rotate in this way to spray liquid is that, firstly, since the nozzle 23 is rotating, the spraying range of the nozzle 23 can be increased, so that the mother liquid can be dispersed in a large range in the furnace to improve thermal efficiency; secondly, when the nozzle 23 rotates, centrifugal force will be generated. Under the action of centrifugal force, some carbide salt particles in the nozzle 231 can be thrown out, reducing the risk of these particles gathering and clogging the nozzle 231.

[0125] The scraper 6 is driven by a driving mechanism to reciprocate between the lower end 3a and the higher end 3b of the material receiving surface 31 along the extension direction of the material receiving surface 31, that is, driven by the driving mechanism, the scraper will move from the lower end 3a to the higher end 3b of the material receiving surface 31, and then return from the higher end 3b to the lower end 3a to wait for the next cycle.

[0126] In order to prevent the scraper 6 from scraping the carbonized salt on the material receiving surface 31 toward the lower end 3a when the scraper 6 returns from the upper end 3b, in this embodiment, the scraper includes a first state and a second state;

[0127] In the first state, the scraper 6 contacts the material receiving surface 31, and the scraper 6 maintains the first state during the process of moving from the lower end 3a to the higher end 3b of the material receiving surface 31 (i.e., upward), so that the scraper 6 can scrape the carbonized salt on the material receiving surface 31 toward the higher end 3b.

[0128] In the second state, the scraper 6 is separated from the material receiving surface 31, and maintains the second state during the process of moving from the high end 3b to the low end 3a of the material receiving surface 31 (i.e., downward), so that the scraper 6 will not scrape the carbonized salt on the material receiving surface 31 during the downward process, thereby preventing the carbonized salt on the material receiving surface 31 from being scraped toward the liquid inlet area 4.

[0129] In order to enable the scraper 6 to realize the above-mentioned two states of walking, in this embodiment, the driving mechanism includes one or more groups of closed-loop chains 51 arranged in the furnace body and driven to rotate by the first motor 54. In this embodiment, Figure 3 As shown, two groups of chains 51 are used, and the two groups of chains 51 are arranged side by side. During the carbonization process, the chains 51 continue to rotate.

[0130] The chain 51 is disposed above the material connection surface 31 and extends along the extension direction of the material connection surface 31 , that is, the chain 51 is also disposed obliquely, and its inclination direction and angle are consistent with the inclination direction and angle of the material connection surface 31 .

[0131] like Figure 2 As shown, one end of the scraper 6 is fixed on the chain 51 and is driven by the chain 51 to reciprocate between the lower end 3a and the upper end 3b of the material receiving surface 31.

[0132] When the chain 51 rotates, the scraper 6 is driven to move. When the scraper 6 moves upward, the scraper 6 is at the lower part of the chain 51, and the end of the scraper 6 away from the chain 51 is in contact with the material receiving surface 31 to scrape the carbide salt on the material receiving surface 31 to move toward the high end 3b; when the scraper 6 moves to the high end 3b position, as the chain 51 continues to rotate, the scraper 6 will flip to the upper part of the chain 51, thereby separating from the material receiving surface 31, and finally the chain 51 will bring the scraper 6 to the lower end 3a of the material receiving surface 31 for the next cycle.

[0133] In this embodiment, Figure 2 and Figure 3 As shown, the chain 51 and the first motor 54 are driven by a sprocket 52. Specifically, the chain 51 is sleeved on two sprockets 52. The sprocket 52 is fixed on a rotating shaft 53 rotatably connected to the first heating furnace 1. The first motor 54 is installed on the outside of the first heating furnace 1 and is connected to one of the rotating shafts 53. The first motor 54 drives the rotating shaft 53 to rotate, thereby driving the sprocket 52 to rotate. The rotation of the sprocket 52 drives the chain 51 to rotate, thereby driving the scraper 6 to move.

[0134] Example 3

[0135] like Figure 6-8 As shown, this embodiment provides a hazardous waste salt carbonization treatment device, which can be used for the secondary carbonization treatment of the first waste salt and the second waste salt in Example 1 and Example 2.

[0136] The hazardous waste salt carbonization treatment device provided in this embodiment is mainly used for carbonization treatment of hazardous waste salt, mainly for carbonization treatment of salt-containing hazardous waste containing organic matter.

[0137] The hazardous waste salt carbonization treatment device provided in this embodiment includes a second heating furnace 7, which is mainly used to heat and carbonize the hazardous waste salt. The second heating furnace 7 can be heated by steam or by electric heating elements.

[0138] In some embodiments, Figure 6 As shown, the second heating furnace 7 mainly includes a second inner shell 72, a second outer shell 71 inserted into the outside of the second inner shell 72, and second end plates 73 arranged at both ends of the second inner shell 72 and the second outer shell 71; the second inner shell 72 and the second outer shell 71 as a whole constitute the surrounding wall of the second heating furnace 7, and the second end plates 73 at both ends constitute the end walls of the second heating furnace 7.

[0139] The second inner shell 72 and the second outer shell 71 are spaced apart to form a second interlayer space 70; Figure 7 As shown, the second inner shell 72 and the second outer shell 71 are both cylindrical structures and are coaxially arranged.

[0140] The second heating furnace 7 is heated by introducing steam into the second interlayer space 70 or by providing an electric heating element in the second interlayer space 70 .

[0141] Take steam heating as an example. Figure 6 As shown, a second steam inlet 731 is provided on the second end plate 73 or the second outer shell 71 for connecting to an external steam pipeline. The steam output from the steam pipeline enters the second interlayer space 70 through the second steam inlet 731 to heat the second inner shell 72, thereby achieving heating inside the second heating furnace 7.

[0142] In order to discharge the condensed water generated by the condensation of steam in the second interlayer space 70 later, a second condensed water outlet 74 is provided at the bottom of the second outer shell 71. In order to control the opening and closing of the second condensed water outlet 74, the second condensed water outlet 74 can be connected to a valve.

[0143] The second heating furnace 7 is provided with a material bed 8 extending along the first direction for placing waste salt to be carbonized. The waste salt here may be the first waste salt and / or the second waste salt mentioned in Example 1, hereinafter collectively referred to as waste salt or hazardous waste salt.

[0144] like Figure 6 As shown, the first direction here can be understood as the length direction of the second heating furnace 7 or the axial direction of the second heating furnace 7 .

[0145] like Figure 7 As shown, the cross section of the material bed 8 in the radial direction of the second heating furnace 7 is in a concave arc shape.

[0146] A rotating shaft 9 is rotatably disposed above the material bed 8 in the second heating furnace 7 and extends along the first direction, and a rotating axis 53 of the rotating shaft 9 is parallel to the first direction; wherein the rotating shaft 9 is rotatably disposed on the two second end plates 73 .

[0147] The rotating shaft 9 is hollow inside to form a channel 91 for steam to pass through, wherein one end of the channel 91 is open for connection with a steam input pipeline, and steam passes into the channel 91 through the steam input pipeline.

[0148] The end of the rotating shaft 9 away from the steam input pipeline is connected to the second motor 92 installed outside the second heating furnace 7, and the rotating shaft 9 is driven to rotate by the second motor 92; in order to ensure that the rotating shaft 9 can rotate normally, the end of the rotating shaft 9 away from the second motor 92 is rotatably connected and communicated with the steam input pipeline. For example, a rotating joint for pipeline connection can be used to achieve the rotational connection and communication between the two.

[0149] like Figure 6 As shown, the rotating shaft 9 is fixedly connected to a plurality of flap members which are spaced apart in sequence along the first direction, and the flap members can rotate together with the rotating shaft 9; the flap members have a cavity 931 which is connected to the channel 91, so that the steam in the channel 91 enters the cavity 931 and heats the flap members, wherein the flap members are made of heat-conducting material, such as hard metal material, such as steel.

[0150] The turning member is turned over driven by the rotating shaft 9 to contact and turn over the waste salt on the material bed 8 .

[0151] During operation, the waste salt to be carbonized is spread on the material bed 8, and steam is introduced into the second interlayer space 70 and the channel 91; and the second motor 92 is started to drive the rotating shaft 9 to rotate, so as to drive the flipping part to flip together; in this way, the hazardous waste salt on the material bed 8 will be gradually carbonized after heating treatment to form carbonized salt (i.e., a mixture of carbide and waste salt).

[0152] During the carbonization process, since the flipping part is constantly rotating and is heated by the steam in the cavity 931, the heated flipping part will continuously contact the hazardous waste salt on the material bed 8 and disturb the hazardous waste salt during the rotation process; the heated flipping part can directly heat the hazardous waste salt when contacting the hazardous waste salt to accelerate the carbonization of the hazardous waste salt. At the same time, the flipping part disturbs and stirs the hazardous waste salt, so that the hazardous waste salt can be better heated for carbonization, thereby improving thermal efficiency.

[0153] In order to allow the hazardous waste salt in the material bed 8 to be fully stirred and turned by the turning member, in this embodiment, the material bed 8 can reciprocate in the second heating furnace 7 along the first direction;

[0154] In this way, during the carbonization process, the turning member stirs and turns the hazardous waste salt on the material bed 8 by rotating, and at the same time, the material bed 8 itself also reciprocates along the first direction, which is equivalent to the material bed 8 shaking left and right, so that the hazardous waste salt on the material bed 8 can be fully stirred and turned by the turning member.

[0155] In other words, assuming that the material bed 8 remains stationary, the hazardous waste salt between two adjacent turning parts on the material bed 8 cannot be stirred and turned by the turning parts; when the material bed 8 is able to shake left and right, the hazardous waste salt on the material bed 8 is equivalent to constantly changing its position, so that the hazardous waste salt between two adjacent turning parts can also be stirred and turned by the turning parts, thereby improving the carbonization efficiency.

[0156] The hazardous waste salt carbonization treatment device also includes a driving assembly for driving the material bed 8 to reciprocate along the first direction, and the driving assembly includes guide rods 82 respectively fixed at both ends of the material bed 8 and extending along the first direction. Figure 7 As shown, two guide rods 82 are respectively arranged at both ends of the material bed 8.

[0157] The guide rod 82 movably passes through the end walls at both ends of the heating furnace, that is, passes through the second end plates 73 at both ends; the guide rod 82 can move relative to the second end plate 73 along the first direction; in this way, the material bed 8 is set up by the guide rod 82, and the material bed 8 can reciprocate as a whole along the first direction together with the guide rod 82.

[0158] In order to reduce the hazardous waste salt from falling from both sides (mainly the front and rear sides) of the material bed 8 , both sides of the material bed 8 can be slidably fitted to the peripheral wall of the second inner shell 72 .

[0159] The driving assembly further includes a power member disposed outside the heating furnace, and the power member is connected to at least one guide rod 82 to drive the guide rod 82 to reciprocate along the first direction. The driving member may be a cylinder, a hydraulic cylinder or a motor, etc. For example, a hydraulic cylinder is fixed to the outer end of one of the guide rods 82; the guide rod 82 is driven to reciprocate along the first direction by the telescopic action of the hydraulic cylinder, thereby realizing the reciprocating movement of the material bed 8 in the first direction.

[0160] Since the material bed 8 needs to be shaken left and right along the first direction, a space for the material bed 8 to move left and right needs to be reserved between the two second end plates 73 and the two ends of the material bed 8. Therefore, in this embodiment, the two ends of the material bed 8 are spaced apart from the end walls of the heating furnace, and the space serves as a space for the material bed 8 to move left and right.

[0161] Due to the existence of the aforementioned gap, the hazardous waste salt on the material bed 8 will fall into the gap from both ends of the material bed 8. Therefore, in the present embodiment, a shielding member 81 extending and retracting along a first direction is connected between the end of the material bed 8 and the end wall of the second heating furnace 7. The shielding member 81 is used to shield the gap between the end of the material bed 8 and the end wall of the second heating furnace 7. The shielding of the shielding member 81 can reduce the hazardous waste salt from falling from both ends of the material bed 8.

[0162] The shielding member 81 may be made of high temperature resistant flexible fabric. When connected, the two ends of the flexible fabric are respectively fixed on the end of the rocking bed and the second end plate 73 .

[0163] In some embodiments, Figure 7 As shown, the flap member includes one or more blades 93 disposed on the rotating shaft 9; for example, in this embodiment, one flap member includes three blades 93, and the three blades 93 are distributed on the rotating shaft 9 in an array with the rotating shaft 9 as the center; Figure 8 As shown, each blade 93 has a cavity 931 formed inside thereof which is in communication with the channel 91 .

[0164] It is worth noting that if Figure 6 As shown, in order to allow hazardous waste salt to enter the material bed 8, in this embodiment, at least one of the second end plates 73 is provided with a furnace opening 732 as a feed opening; the furnace opening 732 is provided with a furnace door 733 that can be opened and closed. During feeding, the hazardous waste salt to be carbonized can be spread on the material bed 8 through the furnace opening 732 by manual operation or mechanical arm operation. During the carbonization process, the furnace door 733 is in a closed state to ensure the sealing of the furnace.

[0165] During operation, steam is introduced into the second interlayer space 70 and the channel 91 respectively, and the second motor 92 is turned on to drive the rotating shaft 9 and the blades 93 to rotate so as to stir and turn the waste salt on the material bed 8; preferably, during carbonization, the temperature in the heating furnace is set between 550°C and 650°C, and a gas is filled into the heating furnace that isolates oxygen, such as nitrogen or steam, to isolate the air to reduce the generation of dioxins.

[0166] It is worth noting that in step S2, since the melting point of salt is about 801°C, the corrosiveness of the molten salt will cause great damage to the equipment and will greatly increase the operating cost, so the carbonization temperature must be controlled below 800°C.

[0167] When the carbonization temperature is below 800°C, dioxins are easily produced because the hazardous waste salt itself contains a large amount of halogen elements. Therefore, in this embodiment, the temperature of the heating furnace is set between 550°C and 650°C, and a gas is introduced into the furnace body to prevent the salt from melting and reduce the production of dioxins.

[0168] Finally, carbide salt is obtained, which is a mixture of carbide and waste salt.

[0169] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A method for treating high-salt wastewater, characterized in that: The steps include: S1, evaporating the wastewater to obtain first waste salt and mother liquor; S2, performing primary carbonization treatment on the mother liquor to obtain a second waste salt; S3, performing secondary carbonization treatment on the first waste salt and / or the second waste salt to obtain carbonized salt; S4, separating the carbide salt to obtain carbide and recyclable salt; In step S2, the mother liquor is subjected to primary carbonization treatment by a mother liquor carbonization treatment device; The mother liquid carbonization treatment device comprises a first heating furnace, a liquid spraying mechanism and a scraper; a material receiving surface is provided at the bottom of the first heating furnace, and the material receiving surface is inclined to form a high end and a low end; a liquid inlet area for storing mother liquid is formed on the lower end side of the material receiving surface inside the first heating furnace; the liquid spraying mechanism comprises a pump and a plurality of nozzles, and the pump is used to extract the mother liquid from the liquid inlet area to the nozzle, and the nozzle sprays the mother liquid in the first heating furnace; the scraper is provided in the first heating furnace, and can be in contact with the material receiving surface to scrape the waste salt falling on the material receiving surface from the lower end to the high end of the inclined surface; A liquid inlet pipe is connected to the liquid outlet end of the pump; the nozzle is rotatably mounted on the liquid inlet pipe around a first axis, wherein the first axis is vertically perpendicular to the axial direction of the first heating furnace; The nozzle comprises a straight pipe section, which is connected to the extension section by rotating around a first axis and is in communication with the extension section; at least two nozzles are arranged at the upper end of the straight pipe section, and the at least two nozzles are distributed in a circular array with the first axis as the center; The spraying direction of the nozzle is horizontal, and the extension line of the spraying direction of the nozzle deviates from the first axis; In step S3, the secondary carbonization treatment of waste salt is carried out by using a hazardous waste salt carbonization treatment device; the hazardous waste salt carbonization treatment device comprises a second heating furnace, a material bed for placing waste salt and extending along a first direction is provided in the second heating furnace, a rotating shaft is rotatably arranged and extends along the first direction above the material bed in the second heating furnace, and the rotation axis of the rotating shaft is parallel to the first direction; the interior of the rotating shaft is hollow to form a channel for steam to pass through; a plurality of flipping members are fixedly connected to the rotating shaft and are spaced in sequence along the first direction; the flipping member has a cavity connected to the channel; the flipping member flips under the drive of the rotating shaft to contact and flip the waste salt on the material bed.

2. A method for treating high-salt wastewater according to claim 1, characterized in that: Before step S1, the following steps are also included: S01. Determine the salt concentration of the wastewater; If the salt concentration of the wastewater is greater than 10%, directly proceed to step S1; If the salt concentration of the wastewater is between 5% and 10%, proceed to step S02; If the salt concentration of the wastewater is between 3% and 5%, directly proceed to step S03; S02, mixing the wastewater to obtain wastewater with a salt concentration of 3%-5%, and then proceeding to step S03; S03, biochemically treating the wastewater to reduce the COD concentration in the wastewater, and then entering step S04; S04, concentrate the wastewater to obtain wastewater with a salt concentration greater than 10%, and then enter step S1.

3. A method for treating high-salt wastewater according to claim 2, characterized in that: In step S03, the wastewater is biochemically treated by using salt-tolerant bacteria; and / or in step S03, the COD concentration in the wastewater is reduced to 300 mg / L-500 mg / L by using biochemical treatment.

4. A method for treating high-salt wastewater according to claim 2, characterized in that: In step S04, the wastewater is concentrated by using reverse osmosis or electrodialysis.

5. A method for treating high-salt wastewater according to claim 2, characterized in that: In step S02, wastewater is mixed with fresh water to obtain wastewater with a salt concentration of 3%-5%.

6. A method for treating high-salt wastewater according to claim 1, characterized in that: The material bed can reciprocate along a first direction in the second heating furnace.

7. A method for treating high-salt wastewater according to claim 1, characterized in that: In step S4, the separation treatment of the carbonized salt comprises the following steps: S41, dissolving the carbonized salt using water to obtain a waste salt solution; S42, filtering, filtering the waste salt solution to achieve solid-liquid separation, and obtaining carbide and brine respectively; S43, evaporation and crystallization, evaporating and crystallizing the salt water to obtain salt that can be recycled; S44, screening and salt separation, screening the salt obtained in step S43 to obtain coarse salt and fine salt respectively.

8. A method for treating high-salt wastewater according to claim 1, characterized in that: Before performing secondary carbonization treatment on the first waste salt and / or the second waste salt in step S3, the first waste salt and / or the second waste salt are preliminarily screened.

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