A graphite purification and washing device with closed-circuit continuous water flow washing

Abstract

The invention discloses a graphite purification and washing device with closed-loop continuous water flow washing, which relates to the technical field of natural graphite purification, and includes a water washing tank, a spraying mechanism, a collecting mechanism, a heating coil, a stirring mechanism, a gas-liquid separation tank, a water washing and drainage tank, a high-concentration alkali-containing wastewater storage tank, and an alkali-containing wastewater reuse treatment system. The invention completes the water immersion, water washing and de-alkaliization of graphite after alkali fusion, and the solid-liquid separation of graphite and liquid in one tank, without external transmission in the middle, simplifying the operation process, reducing equipment and graphite loss; adopting continuous water flow washing to increase the washing speed, reduce the washing time, and reduce the amount of washing water; the high-concentration alkali-containing waste liquid generated after water immersion is collected separately for easy recycling; the low-concentration alkali-containing wastewater generated after water washing is discharged into the alkali-containing wastewater reuse treatment system, realizing the closed-loop circulation of washing water, thereby reducing the amount of fresh water and the discharge of wastewater, and reducing the cost of graphite purification.

Description

Technical Field

[0001] The invention relates to the technical field of natural graphite purification, in particular to a graphite purification and washing device with closed-circuit continuous water flow washing. Background Art

[0002] With the rapid development of the world's industry, graphite has been regarded as one of the important industrial mineral raw materials at home and abroad, and graphite products have played an important role in all walks of life. Naturally occurring graphite ores are rarely pure and often contain a lot of impurities. At present, the purity requirements for graphite products are getting higher and higher, and the purification of graphite is the basis for the preparation of all graphite materials.

[0003] At present, the main methods for graphite purification are divided into two categories: physical purification and chemical purification, including five purification methods: alkali-acid method, chlorination roasting method, hydrofluoric acid method, flotation method and high-temperature purification method. Among them, the alkali-acid method has simple process operation, low production cost, and does not produce toxic and hazardous waste, making it superior in current industrial applications. The method includes systems such as sodium hydroxide-sulfuric acid, sodium hydroxide-hydrochloric acid, sodium hydroxide-hydrochloric acid-nitric acid, etc. The alkali-acid method includes alkali melting process and acid leaching process, in which alkali is first used for high-temperature treatment to produce a chemical reaction to generate water-soluble or acid-soluble salts, and then the acid method is used to remove metal hydroxides and acid-soluble salts such as sodium aluminosilicate. The specific process flow includes graphite + sodium hydroxide → batching → melting → water leaching → washing and de-alkali → acid leaching → washing and de-acidification → dehydration and drying → high carbon graphite.

[0004] As can be seen from the process flow, there are two water washing steps. In order to wash out the alkali and deacidification to neutrality, a large amount of washing water is needed. At present, 1 ton of graphite needs to consume about 40 tons of washing water. In practical applications, in order to achieve a higher purification effect, 0.4-0.7 tons of sodium hydroxide need to be added to 1 ton of graphite raw material during the alkali melting process. This amount far exceeds the theoretical consumption. Therefore, the remaining alkali requires a large amount of water to be repeatedly washed many times to neutrality. This not only consumes a lot of water, but also produces a large amount of wastewater, which is directly discharged after treatment. And in the washing process, as washing and solid-liquid separation of the filter press are carried out alternately, the complexity of the operation is increased, and the loss of graphite will also be caused, thereby increasing the processing cost of the alkali-acid purification. Therefore, it is of great significance to study an environmentally friendly, simple-operation alkali-acid purification water washing device that can solve the above problems and reduce the water consumption and processing cost of the alkali-acid method. Summary of the invention

[0005] The purpose of the present invention is to provide a graphite purification and washing device with closed-loop continuous water flow washing to solve the problem that graphite purification by alkali-acid method requires large consumption of water, large wastewater discharge and high cost.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The invention discloses a graphite purification and washing device for closed-loop continuous water flow washing, comprising a water washing tank, a top surface of the water washing tank being provided with a feed inlet, a spray mechanism being provided inside the water washing tank, a collecting mechanism being provided below the spray mechanism, a heating coil being provided on the inner wall of the water washing tank, a stirring mechanism being provided below the collecting mechanism, the collecting mechanism being connected with a gas-liquid separation tank, the top of the gas-liquid separation tank being connected with a vacuum pump through a pipeline, the bottom of the gas-liquid separation tank being connected with a water washing drainage pool and a high-concentration alkali-containing wastewater storage pool through a pipeline, the water washing drainage pool being connected with an alkali-containing wastewater reuse treatment system through a pipeline, a discharge hopper being provided on the bottom surface of the water washing tank, an emptying port being provided on the bottom side wall of the water washing tank, the emptying port being connected with the high-concentration alkali-containing wastewater storage pool through a pipeline, the emptying port being connected with the alkali-containing wastewater reuse treatment system through another pipeline, and the alkali-containing wastewater reuse treatment system being connected with the spray mechanism through a pipeline.

[0008] Furthermore, the spray mechanism includes a water washing inlet pipe, on which a plurality of spray heads are installed. The water washing inlet pipe extends to the outside of the water washing tank and is connected to a water washing pool, and the water washing pool is connected to the alkaline wastewater reuse treatment system through a pipeline.

[0009] Furthermore, a water inlet valve is installed on the water washing water inlet pipe.

[0010] Furthermore, the stirring mechanism includes a gas stirring assembly and an underwater agitator, the gas stirring assembly includes a perforated aeration pipe, the perforated aeration pipe is arranged at the bottom of the water washing tank, and the perforated aeration pipe is connected to the air compressor through an air supply pipe; the underwater agitator is installed on the side wall of the water washing tank, and the underwater agitator is arranged above the perforated aeration pipe.

[0011] Furthermore, an air supply pipeline valve is installed on the air supply pipe.

[0012] Furthermore, the collecting mechanism includes a collecting pipe, which is connected to the gas-liquid separation tank through a pipeline. A pulse backflushing system is arranged inside the collecting pipe. A filter bag bracket is installed on the bottom surface of the collecting pipe, and a filter bag is sleeved on the outer side of the filter bag bracket.

[0013] Furthermore, a metal filter is arranged inside the drain port.

[0014] Furthermore, a discharge valve is installed on the discharge port of the discharge hopper, a first connecting pipe valve is installed on the pipeline between the gas-liquid separation tank and the vacuum pump, a second connecting pipe valve is installed on the pipeline between the collecting pipe and the gas-liquid separation tank, a third connecting pipe valve is installed on the pipeline between the gas-liquid separation tank and the water washing and drainage tank, a fourth connecting pipe valve is installed on the pipeline between the water washing and drainage tank and the alkaline wastewater reuse treatment system, a fifth connecting pipe valve is installed on the pipeline between the gas-liquid separation tank and the high-concentration alkaline wastewater storage tank, a sixth connecting pipe valve is installed on the pipeline between the emptying port and the high-concentration alkaline wastewater storage tank, and a seventh connecting pipe valve is installed on the pipeline between the emptying port and the alkaline wastewater reuse treatment system.

[0015] Compared with the prior art, the beneficial technical effects of the present invention are:

[0016] The present invention completes the immersion, washing and de-alkali of graphite after alkali fusion and the solid-liquid separation of graphite and liquid in one tank, without external transmission in the middle, simplifying the operation process and reducing the loss of equipment and graphite; adopts continuous water flow washing, continuous water inlet and continuous water outlet, so that the water in the washing tank is continuously renewed, the concentration of alkali in the water will be rapidly reduced, the washing speed is improved, the washing time is reduced, and the amount of water used for washing is reduced; the high-concentration alkali-containing waste liquid generated after immersion is collected separately for easy recycling; the low-concentration alkali-containing waste water generated after washing is discharged into the alkali-containing waste water reuse treatment system, and the water treated by neutralization of acid-containing waste water, ultrafiltration to remove impurities such as suspended matter and nanofiltration desalination is returned to the water tank The washing water pool is reused to realize the closed-loop circulation of washing water, thereby reducing the amount of fresh water and the discharge of wastewater, and reducing the cost of graphite purification; the filter bag is used to drain water through suction filtration, the filter bag has a good interception effect, high solid-liquid separation efficiency, and can reduce graphite loss. At the same time, in order to prevent the filter bag from being blocked, aeration is used to flush the outer surface of the filter bag during the water washing process to prevent a large amount of graphite from accumulating on it and affecting the water output. In addition, a pulse backwashing system is set in the water washing device for regularly backwashing and cleaning the filter bag; compared with the traditional process, the present invention can reduce the use of fresh water by more than 50%, reduce production costs, and improve the environmental and social benefits of the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described below in conjunction with the accompanying drawings.

[0018] Figure 1 This is a schematic diagram of the structure of a graphite purification and washing device for closed-loop continuous water washing according to the present invention;

[0019] Description of the reference numerals: 1. feed port; 2. water washing inlet pipe; 3. water washing pool; 4. filter bag support; 5. vacuum pump; 6. gas-liquid separation tank; 7. water washing drainage pool; 8. alkaline wastewater reuse treatment system; 9. high-concentration alkaline wastewater storage tank; 10. perforated aeration pipe; 11. underwater agitator; 12. heating coil; 13. filter bag; 14. water washing tank; 15. air compressor; 16. air supply pipe; 17. discharge port; 1 8. Discharge hopper; 19. Collection pipe; 20. Sprinkler head; 21. Drain port; 22. Pulse backflush system; 23. Air supply pipeline valve; 24. Metal filter; 25. Discharge valve; 26. First connecting pipe valve; 27. Second connecting pipe valve; 28. Third connecting pipe valve; 29. ​​Fourth connecting pipe valve; 30. Fifth connecting pipe valve; 31. Sixth connecting pipe valve; 32. Water inlet valve; 33. Seventh connecting pipe valve. DETAILED DESCRIPTION

[0020] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0021] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. The meaning of "several" is one or more, unless otherwise clearly and specifically defined.

[0022] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by the terms "up", "down", "front", "back", "left", "right", etc. are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0023] like Figure 1As shown, a graphite purification and washing device for closed-loop continuous water flow washing comprises a water washing tank 14, the top surface of the water washing tank 14 is provided with a feed port 1, the interior of the water washing tank 14 is provided with a spraying mechanism, a collecting mechanism is provided below the spraying mechanism, a heating coil 12 is provided on the inner wall of the water washing tank 14, a stirring mechanism is provided below the collecting mechanism, the collecting mechanism is connected to a gas-liquid separation tank 6, the top of the gas-liquid separation tank 6 is connected to a vacuum pump 5 through a pipeline, the bottom of the gas-liquid separation tank 6 is connected to a water washing drainage pool 7 and a high-concentration alkali-containing wastewater storage tank 9 through a pipeline, and the water washing drainage pool 7 is connected to an alkali-containing wastewater reuse area through a pipeline. The water washing tank 14 is connected with the treatment system 8, a discharge hopper 18 is arranged on the bottom surface of the water washing tank 14, and an emptying port 21 is arranged on the bottom side wall of the water washing tank 14, the emptying port 21 is connected with the high-concentration alkaline wastewater storage tank 9 through a pipeline, the emptying port 21 is connected with the alkaline wastewater reuse treatment system 8 through another pipeline, and the alkaline wastewater reuse treatment system 8 is connected with the spray mechanism through a pipeline; specifically, the water washing tank can be circular, square and rectangular; the alkaline wastewater reuse treatment system includes three processes: acid-base neutralization, ultrafiltration to remove suspended matter and other impurities, and nanofiltration desalination, and the treated water is returned to the water washing pool to realize the closed-loop circulation of washing water.

[0024] Specifically, the spray mechanism includes a water washing inlet pipe 2, on which a plurality of spray heads 20 are installed. The water washing inlet pipe 2 extends to the outside of the water washing tank 14 and is connected to a water washing pool 3. The water washing pool 3 is connected to the alkaline wastewater reuse treatment system 8 through a pipeline; an inlet valve 32 is installed on the water washing inlet pipe 2.

[0025] The stirring mechanism includes a gas stirring assembly and an underwater stirrer 11. The gas stirring assembly includes a perforated aeration pipe 10. The perforated aeration pipe 10 is arranged at the bottom of the water washing tank 14. The perforated aeration pipe 10 is connected to the air compressor 15 through the air supply pipe 16. The underwater stirrer 11 is installed on the side wall of the water washing tank 14, and the underwater stirrer 11 is arranged above the perforated aeration pipe 10. The air supply pipe 16 is equipped with an air supply pipeline valve 23. Specifically, the perforated aeration pipe is a medium bubble air diffusion device, which is made of a steel pipe or plastic pipe with a diameter between 25 and 50 mm. There are holes with a diameter of 3 to 5 mm on both sides of the pipe wall at an angle of 45° downward, and the spacing is 50 to 100 mm. Air overflows from the holes. The role of the bubbles is to stir and mix, and the rising bubbles play a flushing role on the outer surface of the filter bag to prevent a large amount of graphite from accumulating on it during filtration, blocking the filter bag and affecting the water output.

[0026] The collecting mechanism includes a collecting pipe 19, which is connected to the gas-liquid separation tank 6 through a pipeline. A pulse back-blowing system 22 is arranged inside the collecting pipe 19. A filter bag bracket 4 is installed on the bottom surface of the collecting pipe 19, and a filter bag 13 is sleeved on the outside of the filter bag bracket 4. The pulse back-blowing system removes the graphite attached to the outer surface of the filter bag by spraying compressed air, and is used to regularly back-blow and clean the filter bag to prevent graphite from remaining on the surface of the filter bag or clogging the filter bag. The pulse back-blowing system is composed of an air storage tank, an electromagnetic pulse valve, a pulse controller, and compressed air. The high-pressure air sprayed out for a moment each time has a good cleaning effect. The filter bag is a cylindrical bag made of a filter cloth with a certain mesh number, and the mesh number is determined by the mesh number of the purified graphite. The number of filter bags can also be adjusted according to the amount of graphite purification and the size of the water washing tank. The number of filter bags in this embodiment is two, and the inner wall of the filter bag is fixed on the filter bag bracket.

[0027] A metal filter screen 24 is disposed inside the drain port 21 , and the metal filter screen is used to filter graphite to prevent the graphite from entering the alkaline wastewater reuse treatment system 8 and the high-concentration alkaline wastewater storage tank 9 along the pipeline.

[0028] A discharge valve 25 is installed on the discharge port 17 of the discharge hopper 18, a first connecting pipe valve 26 is installed on the pipeline between the gas-liquid separation tank 6 and the vacuum pump 5, a second connecting pipe valve 27 is installed on the pipeline between the collecting pipe 19 and the gas-liquid separation tank 6, a third connecting pipe valve 28 is installed on the pipeline between the gas-liquid separation tank 6 and the water washing and drainage pool 7, a fourth connecting pipe valve 29 is installed on the pipeline between the water washing and drainage pool 7 and the alkaline wastewater reuse treatment system 8, a fifth connecting pipe valve 30 is installed on the pipeline between the gas-liquid separation tank 6 and the high-concentration alkaline wastewater storage tank 9, a sixth connecting pipe valve 31 is installed on the pipeline between the emptying port 21 and the high-concentration alkaline wastewater storage tank 9, and a seventh connecting pipe valve 33 is installed on the pipeline between the emptying port 21 and the alkaline wastewater reuse treatment system 8.

[0029] The method for water immersion of alkali-fused graphite is as follows:

[0030] The alkali-melted graphite is added to the washing tank 14 from the feed port 1, and then the water inlet valve 32 is opened. The water for immersion is added to the designed position by the spray head 20 connected to the washing water inlet pipe 2 to stop the water inlet; the air supply pipeline valve 23 is opened, and the air for stirring is supplied from the air supply pipe 16 to the perforated aeration pipe 10, and the air is used to stir the immersion process. The underwater stirrer 11 can also be used to further promote the stirring and mixing of the graphite, so as to promote the remaining sodium hydroxide after alkali melting and the water-soluble substances generated by the reaction of impurities with alkali to dissolve into the water; at the same time, in order to ensure the improvement of solubility, the heating coil 12 around the washing tank 14 is used to heat the immersion water to ensure that the temperature of the immersion process is about 50°C; after 30 minutes of immersion, the air supply pipeline valve 23 and the underwater stirrer 11 are closed, and the first connecting pipe valve 26, the second connecting pipe valve 27, and the fifth connecting pipe valve 30 are opened to discharge the high-concentration alkali-containing waste liquid after immersion to the high-concentration alkali-containing waste liquid storage tank 9 for subsequent recycling.

[0031] The specific discharge process is: turn on the vacuum pump 5 for suction, the water-soaked alkali liquid in the water washing tank 14 enters the collecting pipe 19 through the filter bag 13, and then flows through the gas-liquid separation tank 6 to the high-concentration alkali-containing waste liquid storage tank 9 for suction and drainage. In order to fully recover all the alkali, open the sixth connecting pipe valve 31 to discharge the small amount of alkali liquid remaining at the bottom of the pool from the drain port 21 to the high-concentration alkali-containing waste liquid storage tank 9. The entire water immersion and graphite dehydration process is completed simultaneously in one water washing tank. After the water-soaked alkali liquid is discharged, the vacuum pump can continue to be turned on for a certain period of time. At this time, the graphite attached to the filter bag is sucked dry and the alkali liquid is completely removed, which is conducive to the following rapid water washing. After the whole process is completed, the fifth connecting pipe valve 30 and the sixth connecting pipe valve 31 are closed, and the water washing process begins.

[0032] The method for removing alkali from the water-soaked graphite by continuous water washing in a closed loop is as follows:

[0033] Open the water inlet valve 32 and the air supply pipeline valve 23 to start water intake. After reaching the set water level, open the first connecting pipe valve 26, the second connecting pipe valve 27, the third connecting pipe valve 28, and the fourth connecting pipe valve 29 to start continuous water flow washing.

[0034] The specific washing process is as follows: the washing water continuously enters the washing tank 14 from the spray head 20 connected to the washing water inlet pipe 2, and the water in the washing tank 14 is sucked by the vacuum pump 5. The water in the washing tank 14 enters the collecting pipe 19 through the filter bag 13, and then flows through the gas-liquid separation tank 6 to the washing drainage pool 7. With the continuous inflow and outflow of water, the pH of the water in the pool continues to decrease, and the washing and de-alkali are completed after washing to neutrality. Close the water inlet valve 32, continue to discharge all the washing water in the washing tank 14 to the washing drainage pool 7, and finally open the fourth connecting pipe valve 29 to discharge the water in the washing drainage pool 7 to the alkaline wastewater reuse treatment system 8, and return the water after neutralization of the acidic wastewater, ultrafiltration to remove suspended matter and other impurities, and nanofiltration desalination treatment to the washing water pool 3, so as to realize the closed-loop recycling of washing water. After the washing water is discharged, all valves that have been opened are closed, the water inlet valve 32 is opened, a small amount of clean water is introduced to mix with the washed graphite, and the discharge valve 25 is opened to discharge the graphite and water mixture to the acid leaching tank behind, completing the whole process of water washing and de-alkali.

[0035] During the washing process, according to the actual washing situation, after washing for a period of time, the washing water in the washing tank can be completely drained once, and then water can be added to perform a second washing again.

[0036] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A graphite purification and washing device with closed-circuit continuous water flow washing, characterized in that: The invention comprises a water washing tank (14), wherein a feed port (1) is arranged on the top surface of the water washing tank (14), a spraying mechanism is arranged inside the water washing tank (14), a collecting mechanism is arranged below the spraying mechanism, a heating coil (12) is arranged on the inner wall of the water washing tank (14), a stirring mechanism is arranged below the collecting mechanism, the collecting mechanism is connected to a gas-liquid separation tank (6), the top of the gas-liquid separation tank (6) is connected to a vacuum pump (5) through a pipeline, the bottom of the gas-liquid separation tank (6) is connected to a water washing drainage pool (7) and a high-concentration alkali-containing wastewater storage pool (9) through a pipeline, the water washing drainage pool (7) is connected to an alkali-containing wastewater reuse treatment system (8) through a pipeline, a discharge hopper (18) is arranged on the bottom surface of the water washing tank (14), and an emptying port (21) is arranged on the bottom side wall of the water washing tank (14), the emptying port (21) is connected to a high-concentration alkali-containing wastewater storage pool (9), the water washing drainage pool (7) is connected to an alkali-containing wastewater reuse treatment system (8) through a pipeline, The high-concentration alkali-containing wastewater storage tank (9) is connected to the drain port (21) through another pipeline and connected to the alkali-containing wastewater reuse treatment system (8), and the alkali-containing wastewater reuse treatment system (8) is connected to the spray mechanism through a pipeline; the spray mechanism comprises a water washing inlet pipe (2), and a plurality of spray heads (20) are installed on the water washing inlet pipe (2). The water washing inlet pipe (2) extends to the outside of the water washing tank (14) and is connected to a water washing pool (3), and the water washing pool (3) is connected to the alkali-containing wastewater reuse treatment system (8) through a pipeline; the water in the water washing drainage pool (7) is discharged to the alkali-containing wastewater reuse treatment system (8), and the water after neutralization of the acid-containing wastewater, removal of suspended impurities by ultrafiltration and desalination by nanofiltration is returned to the water washing pool (3), so as to realize the closed-loop circulation of washing water.

2. The graphite purification and washing device with closed-circuit continuous water flow washing according to claim 1 is characterized in that: The water washing water inlet pipe (2) is provided with a water inlet valve (32).

3. The graphite purification and washing device with closed-circuit continuous water flow washing according to claim 1 is characterized in that: The stirring mechanism comprises a gas stirring component and an underwater stirrer (11); the gas stirring component comprises a perforated aeration pipe (10); the perforated aeration pipe (10) is arranged at the bottom of the water washing tank (14); the perforated aeration pipe (10) is connected to an air compressor (15) via an air supply pipe (16); the underwater stirrer (11) is installed on the side wall of the water washing tank (14), and the underwater stirrer (11) is arranged above the perforated aeration pipe (10).

4. The graphite purification and washing device with closed-circuit continuous water flow washing according to claim 3 is characterized in that: An air supply pipeline valve (23) is installed on the air supply pipe (16).

5. The graphite purification and washing device with closed-circuit continuous water flow washing according to claim 1 is characterized in that: The collecting mechanism comprises a collecting pipe (19), the collecting pipe (19) being connected to the gas-liquid separation tank (6) via a pipeline, a pulse backflush system (22) being arranged inside the collecting pipe (19), a filter bag holder (4) being installed on the bottom surface of the collecting pipe (19), and a filter bag (13) being sleeved on the outer side of the filter bag holder (4).

6. The graphite purification and washing device with closed-circuit continuous water flow washing according to claim 1 is characterized in that: A metal filter screen (24) is provided inside the drain port (21).

7. The graphite purification and washing device with closed-circuit continuous water flow washing according to claim 5 is characterized in that: A discharge valve (25) is installed on the discharge port (17) of the discharge hopper (18), a first connecting pipe valve (26) is installed on the pipeline between the gas-liquid separation tank (6) and the vacuum pump (5), a second connecting pipe valve (27) is installed on the pipeline between the collection pipe (19) and the gas-liquid separation tank (6), a third connecting pipe valve (28) is installed on the pipeline between the gas-liquid separation tank (6) and the water washing and drainage tank (7), and a third connecting pipe valve (28) is installed on the pipeline between the water washing and drainage tank (7) and the alkaline wastewater. A fourth connecting pipe valve (29) is installed on the pipeline between the reuse treatment system (8), a fifth connecting pipe valve (30) is installed on the pipeline between the gas-liquid separation tank (6) and the high-concentration alkali-containing wastewater storage tank (9), a sixth connecting pipe valve (31) is installed on the pipeline between the drain port (21) and the high-concentration alkali-containing wastewater storage tank (9), and a seventh connecting pipe valve (33) is installed on the pipeline between the drain port (21) and the alkali-containing wastewater reuse treatment system (8).

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