Device and system for treating high-solid thick slurry ammonium chloride salt rare earth wastewater

Abstract

The utility model relates to the technical field of rare earth wastewater treatment, in particular to a device and a system for treating high-solid thick slurry ammonium chloride salt rare earth wastewater, which comprise a neutralization reaction tank, the neutralization reaction tank is connected with a steam stripping deamination tower, the steam stripping deamination tower is connected with a heat exchange device, and the heat exchange device is also connected with the neutralization reaction tank. When in use, the pretreated rare earth wastewater stock solution firstly exchanges heat with the deaminated solution, and then is subjected to neutralization reaction; after the neutralization reaction, steam stripping deamination is carried out, ammonia in the wastewater is removed through steam stripping in a deamination tower, ammonia gas overflows from waste liquid, and high-temperature deaminated liquid at the bottom of the tower is conveyed to a shell layer of a heat exchange device; carrying out heat exchange on the deaminated liquid and the rare earth wastewater stock solution; and carrying out downstream evaporation drying treatment on the deaminated liquid after heat exchange.

Description

Technical Field

[0001] The utility model relates to the technical field of rare earth wastewater treatment, in particular to a device and a system for treating high-solid concentrated slurry ammonium chloride salt rare earth wastewater. Background Art

[0002] Most of the rare earth elements in ionic rare earth ores exist in ionic phase, and the rare earth content is low. Currently, chemical leaching is mainly used for mineral processing and extraction. During the leaching and separation and purification process, ammonia saponification wastewater, strong alkali saponification wastewater, hydrochloric acid stripping wastewater, ammonium bicarbonate precipitation wastewater and oxalic acid precipitation of a large amount of ammonia nitrogen wastewater will be generated.

[0003] At present, the presence of high solid content concentrated slurry in the process of rare earth production enterprises treating high ammonium chloride wastewater will bring more inconvenience to the treatment process. At the same time, more steam will be used in the stripping and deammoniation process of rare earth wastewater. After deammoniation, there is a lot of heat in the liquid. If it is not recovered, it will cause heat loss. If conventional heat exchangers are used for recovery, it will cause heat exchanger fouling and reduce heat exchange efficiency. At the same time, it will have a great impact on the stable and continuous operation of the system and subsequent evaporation treatment. Utility Model Content

[0004] The purpose of the utility model is to provide a device and system for treating high-solid concentrated ammonium chloride rare earth wastewater, so as to solve the technical problem in the prior art that more steam is used in the stripping and deammoniation process of rare earth wastewater, and a large amount of heat is contained in the liquid after deammoniation. If it is not recovered, heat loss will be caused.

[0005] The utility model discloses a system for treating high-solid concentrated ammonium chloride salt rare earth wastewater, comprising a neutralization reaction tank connected to a stripping deamination tower, the stripping deamination tower connected to a heat exchange device, and the heat exchange device is also connected to the neutralization reaction tank.

[0006] When in use, the raw rare earth wastewater liquid after pretreatment is first heat exchanged with the deammonified liquid, and then a neutralization reaction is carried out; after the neutralization reaction, steam stripping and deammonification are carried out, and ammonia in the wastewater is removed by steam stripping in the deammonification tower, and ammonia overflows from the waste liquid. The high-temperature deammonified liquid at the bottom of the tower is transported to the shell layer of the heat exchange device; the deammonified liquid after deammonification is heat exchanged with the raw rare earth wastewater liquid; the deammonified liquid after heat exchange is subjected to downstream evaporation and drying treatment.

[0007] Before the steam stripping and deammoniation process, the raw rare earth wastewater solution absorbs the heat in the deammoniation liquid through heat exchange, which reduces the consumption of steam for steam stripping and deammoniation and improves the heat utilization efficiency in the system.

[0008] Furthermore, the heat exchange device is also connected to an evaporative drying device.

[0009] A device for treating high-solid concentrated ammonium chloride rare earth wastewater, used in the above system

[0010] Furthermore, the device includes a heat exchange device, and the heat exchange device includes a shell, and a stirring structure and a heat exchange structure are arranged in the shell.

[0011] Furthermore, the stirring structure includes a stirring motor, the stirring motor is connected to a driving rod, the driving rod is provided with stirring blades, and the stirring blades are located in the shell.

[0012] By setting a stirring motor and stirring blades, the stirring motor rotates to drive the driving rod to rotate, and the driving rod drives the stirring blades to rotate. The stirring blades stir the high-solid slurry to prevent solid particles from adhering to the wall of the heat exchange tube, while enhancing heat transfer and improving heat exchange efficiency.

[0013] Furthermore, the heat exchange structure includes a heat exchange tube bundle located in the shell.

[0014] Furthermore, the heat exchange tube bundle is a spiral tube or a straight tube.

[0015] Furthermore, the heat exchange device is a vertical shell and tube heat exchanger.

[0016] Furthermore, a stirring chamber for stirring structure activities is provided in the middle of the heat exchange tube bundle.

[0017] By setting up a stirring chamber, it is ensured that the stirring structure has enough space for stirring, thereby ensuring heat exchange efficiency.

[0018] Furthermore, a cleaning device is provided on the upper portion of the heat exchange tube bundle.

[0019] By providing a cleaning device, the heat exchange tube bundle can be cleaned to avoid too much solid accumulation in the shell to affect the heat exchange.

[0020] Compared with the prior art, the utility model has the following beneficial effects:

[0021] 1. The utility model aims at high-solid concentrated slurry wastewater in the process of rare earth ammonium chloride wastewater treatment, and provides a device and system for treating high-solid concentrated slurry ammonium chloride rare earth wastewater. The system effectively recovers the heat in the liquid after deamination, reduces the steam consumption of the stripping deamination tower, and the thick slurry heat exchange device is set to effectively solve the problem of heat exchanger fouling;

[0022] 2. The utility model has a simple process flow, high heat utilization efficiency, low operation and maintenance costs, and the overall system reduces steam consumption by more than 10%. It improves the heat transfer efficiency of the heat exchanger and extends the heat exchange cleaning cycle, which has good energy-saving and operation cost-saving benefits;

[0023] 3. The concentration of calcium chloride in the deammoniation liquid is high, and the solid particles in the solution are easy to adhere to the wall of the heat exchange tube. The heat exchange device is provided with a stirring motor and stirring blades. The stirring motor rotates to drive the driving rod to rotate, and the driving rod drives the stirring blades to rotate. The stirring blades stir the high-solid slurry to prevent the solid particles from adhering to the wall of the heat exchange tube, and at the same time strengthen the heat transfer and improve the heat exchange efficiency;

[0024] 4. By setting up a stirring chamber, ensure that the stirring structure has enough space for stirring and ensure heat exchange efficiency;

[0025] 5. By setting up a cleaning device, the heat exchange tube bundle can be cleaned to avoid too much solid accumulation in the shell to affect the heat exchange. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 This is a flow chart of the rare earth wastewater treatment system of the utility model.

[0028] Figure 2 This is a schematic diagram of the structure of the heat exchange device of the utility model.

[0029] In the above drawings, the meanings of the various marks are: 1-neutralization reaction tank, 2-stripping deamination tower, 3-heat exchange device, 4-shell, 5-stirring motor, 6-driving rod, 7-stirring blade, 8-heat exchange tube bundle, 9-stirring chamber, 10-cleaning device. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the implementation methods of the utility model clearer, the technical solutions in the implementation methods of the utility model are clearly and completely described below. Obviously, the described implementation methods are only part of the implementation methods of the utility model, not all of the implementation methods.

[0031] Example 1

[0032] This embodiment discloses a device for treating high-solid concentrated ammonium chloride rare earth wastewater, such as Figure 1-Figure 2As shown, the device includes a heat exchange device 3, which is a vertical shell and tube heat exchanger. The heat exchange device 3 includes a shell 4, and a stirring structure and a heat exchange structure are arranged in the shell 4. The stirring structure includes a stirring motor 5, and the stirring motor 5 is connected to a driving rod 6. The driving rod 6 is provided with stirring blades 7, and the stirring blades 7 are located in the shell 4. The heat exchange structure includes a heat exchange tube bundle 8 located in the shell 4, and the heat exchange tube bundle 8 is a straight tube. The device also includes a neutralization reaction tank 1 and a stripping deamination tower 2.

[0033] By arranging a stirring motor 5 and a stirring blade 7, the stirring motor 5 rotates to drive the driving rod 6 to rotate, and the driving rod 6 drives the stirring blade 7 to rotate. The stirring blade 7 stirs the high-solid slurry to prevent solid particles from adhering to the wall of the heat exchange tube, while strengthening heat transfer and improving heat exchange efficiency.

[0034] Example 2

[0035] This embodiment discloses a device for treating high-solid concentrated ammonium chloride rare earth wastewater, such as Figure 1-Figure 2 As shown, the only improvement based on Example 1 is that a stirring chamber 9 for stirring structure activities is provided in the middle of the heat exchange tube bundle 8, and a cleaning device 10 is provided on the upper part of the heat exchange tube bundle 8.

[0036] By providing the stirring chamber 9, it is ensured that the stirring structure has enough space for stirring, thereby ensuring the heat exchange efficiency.

[0037] By providing the cleaning device 10 , the heat exchange tube bundle 8 can be cleaned to avoid too much solid accumulation in the shell 4 to affect the heat exchange.

[0038] Application Example 1

[0039] In this application example, a device for treating high-solid concentrated ammonium chloride rare earth wastewater is used in any one of Examples 1-2. The treatment volume of ammonium chloride rare earth wastewater is 10m 3 / h, the concentration of ammonium chloride in rare earth wastewater is about 10%, the ammonia nitrogen content is>25000mg / L, PH=3~7, and the design temperature is room temperature.

[0040] The pretreated ammonium chloride rare earth wastewater raw liquid enters the heat exchange tube bundle 8 of the concentrated slurry heat exchange device 3, and the deammoniated liquid (~80°C) enters the shell layer of the concentrated slurry heat exchange device 3. The stirring rate of the stirring structure in the heat exchange device 3 is controlled within 100 rpm to stir the deammoniated liquid, which flows in a turbulent state to enhance heat transfer. After heat exchange, the temperature of the rare earth wastewater raw liquid is raised to above 70°C.

[0041] The calcium hydroxide solution prepared by slaked lime is transported to the neutralization reaction tank 1 to undergo a neutralization reaction with the heated rare earth wastewater stock solution. The heated rare earth wastewater stock solution also accelerates the neutralization reaction process and improves the reaction efficiency.

[0042] The mixed liquid after the neutralization reaction is then transported to the stripping deamination tower 2. The wastewater flows downward step by step through the tower plates in the tower. The original wastewater absorbs the heat of steam in the stripping deamination tower. The ammonia in the wastewater overflows and flows out from the top of the tower into the ammonia absorption system. The heated deammoniation liquid is transported to the concentrated slurry heat exchange device 3. The deammoniation liquid after heat exchange and cooling enters the downstream evaporation and drying system.

[0043] In this embodiment, for every ton of rare earth wastewater raw liquid with an ammonium chloride concentration of about 10%, an ammonia nitrogen content of >25000 mg / L, and a pH of 3-7 treated, a concentrated slurry heat exchange device 3 is provided to recover the heat of the liquid after deamination, thereby reducing the saturated steam consumption of the stripping deamination tower by 10% (~20 kg); the concentrated slurry heat exchange device 3 is provided with a mechanical agitator, which effectively improves the heat transfer efficiency and extends the cleaning cycle of the concentrated slurry heat exchanger (the number of cleaning times can be reduced by 1-2 times per year).

[0044] Application Example 2

[0045] This application example is improved on the basis of application example 1 except that the heat exchange device in the above-mentioned device for treating high-solid-concentration ammonium chloride rare earth wastewater is not used.

[0046] The specific steps are as follows: In this embodiment, the water volume of ammonium salt rare earth wastewater treatment is 10m 3 / h, the concentration of ammonium chloride in rare earth wastewater is about 10%, the ammonia nitrogen content is>25000mg / L, PH=3~7, and the design temperature is room temperature.

[0047] The pretreated ammonium chloride rare earth wastewater enters the neutralization reaction device, and reacts with the calcium hydroxide solution prepared by slaked lime in the neutralization reaction tank 1. After the reaction, the mixed liquid emulsion directly enters the deamination tower for deamination, and the deamination liquid enters the downstream treatment process. Due to the low temperature of the reaction liquid, in order to ensure the ammonia nitrogen removal rate, more steam needs to be introduced during the deamination process, and the amount of steam introduced is about 2t / h. At the same time, the evaporated ammonia also contains more uncondensed steam. As the ammonia enters the downstream unit, more cooling water is required, and the ammonia concentration is lower.

[0048] In Application Example 1, the amount of steam consumed to process 1 ton of ammonium chloride stock solution is 180 kg, while without setting the heat exchange device 3, the amount of steam consumed is 200 kg. Based on the steam cost of about 200 yuan per ton, the steam cost is saved by about 20 yuan for each ton of ammonium chloride stock solution processed.

[0049] The above are the implementation methods listed in this embodiment, but this embodiment is not limited to the above optional implementation methods. Those skilled in the art can arbitrarily combine the above methods to obtain other various implementation methods. Anyone can derive other various forms of implementation methods under the inspiration of this embodiment. The above specific implementation methods should not be understood as limiting the scope of protection of this embodiment. The scope of protection of this embodiment shall be based on the definition in the claims, and the description can be used to interpret the claims.

Claims

1. A system for treating high-solid concentrated ammonium chloride rare earth wastewater, characterized in that: The invention comprises a neutralization reaction tank (1), wherein the neutralization reaction tank (1) is connected to a stripping deamination tower (2), wherein the stripping deamination tower (2) is connected to a heat exchange device (3), and wherein the heat exchange device (3) is also connected to the neutralization reaction tank (1).

2. A system for treating high-solid concentrated ammonium chloride rare earth wastewater according to claim 1, characterized in that: The heat exchange device (3) is also connected to an evaporative drying device.

3. A device for treating high-solid concentrated ammonium chloride rare earth wastewater, characterized in that: The method is used in a system for treating high-solid-concentration ammonium chloride rare earth wastewater as described in any one of claims 1-2.

4. The device for treating high-solid concentrated ammonium chloride rare earth wastewater according to claim 3, characterized in that: The device comprises a heat exchange device (3), wherein the heat exchange device (3) comprises a shell (4), and a stirring structure and a heat exchange structure are arranged inside the shell (4).

5. The device for treating high-solid concentrated ammonium chloride rare earth wastewater according to claim 4, characterized in that: The stirring structure comprises a stirring motor (5), the stirring motor (5) is connected to a driving rod (6), a stirring blade (7) is arranged on the driving rod (6), and the stirring blade (7) is located in the housing (4).

6. The device for treating high-solid concentrated ammonium chloride rare earth wastewater according to claim 5, characterized in that: The heat exchange structure comprises a heat exchange tube bundle (8) located in a shell (4).

7. The device for treating high-solid concentrated ammonium chloride rare earth wastewater according to claim 6, characterized in that: The heat exchange tube bundle (8) is a spiral tube or a straight tube.

8. The device for treating high-solid concentrated ammonium chloride rare earth wastewater according to claim 6, characterized in that: A stirring chamber (9) for stirring structure movement is provided in the middle of the heat exchange tube bundle (8).

9. The device for treating high-solid concentrated ammonium chloride rare earth wastewater according to claim 6, characterized in that: A cleaning device (10) is provided on the upper part of the heat exchange tube bundle (8).

10. The device for treating high-solid concentrated ammonium chloride rare earth wastewater according to claim 4, characterized in that: The heat exchange device (3) is a vertical shell and tube heat exchanger.

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