Zero-emission pretreatment system and method for re-separating by-product carnallite

Abstract

The invention discloses a zero-emission pretreatment system and method for re-separating by-product carnallite, and the pretreatment system comprises a carnallite crushing mechanism which is used for carrying out rough crushing on carnallite contained in a ton bag; the screening mechanism is used for screening coarse broken products, one part of the screened products are sent into the primary dissolving mechanism, and the other part of the screened products are sent back to the carnallite crushing mechanism; the primary dissolving mechanism is used for dissolving and precipitating the screened carnallite to obtain supernate; the dissolving mechanism is used for fully dissolving and diluting the supernate again; the filtering mechanism is used for filtering the solution obtained by the dissolving mechanism. According to the pretreatment system and method provided by the invention, the carnallite of the coal plant can be effectively and fully treated and dissolved, the water inlet index requirement of the salt separation device is met, the load of a filter membrane in the salt separation device is reduced, scaling and pollution blockage of the filter membrane are avoided, and the salt separation treatment efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment, and in particular relates to a pretreatment system and method for re-salting salts with zero emission of by-products. Background Art

[0002] After treating coal chemical wastewater, a large amount of crystalline mixed salts will be produced. The disposal of these salts remains a difficult problem for companies implementing zero wastewater discharge. Due to the complexity of the wastewater quality of coal chemical enterprises, the overall recovery rate of by-product salts is relatively low, and the amount of salts produced is large. In addition, the quality of crystalline salts is still inferior to that of industrial salts. For example, there are still differences in indicators such as salt purity, particle uniformity, and total ammonium content, which makes the by-products low in price or difficult to sell. Crystalline salts are easily soluble in water and usually contain organic matter and even heavy metals, making them difficult to dispose of as ordinary solid waste. Even if they are disposed of as hazardous waste at a high cost, due to their extremely large output, general hazardous waste disposal centers find it difficult to dispose of them.

[0003] The primary targets for separation during salt crystallization in high-salt wastewater, such as those from coal chemical industries, are sodium chloride and sodium sulfate. This is because chloride and sulfate ions generally make up the majority of anions in wastewater, while sodium ions predominate as monovalent cations. After a series of treatments, divalent cations are replaced with sodium ions through chemical softening or ion exchange processes.

[0004] There are two main approaches to salt separation crystallization technology: one is to directly utilize the concentration and solubility differences of different inorganic salts in wastewater, and achieve salt separation by controlling the appropriate operating temperature and concentration multiples during the crystallization process, which is commonly known as the thermal salt separation crystallization process; the other is to utilize the differences in ionic radius or charge characteristics of chloride ions and sulfate ions, and achieve separation or enrichment of different salts through a membrane separation process before crystallization, and then use a thermal crystallization process to obtain a solid, which is the membrane salt separation crystallization process.

[0005] After the salt separation technology matures, the miscellaneous salt needs to be separated and processed to reduce disposal costs. As the storage time increases, the miscellaneous salt clumps seriously, making it very difficult to crush and dissolve the salt, resulting in low work efficiency. In addition, due to the insufficient crushing particle size, the equipment is seriously blocked, and manual operation cannot guarantee continuous and uniform dissolution, resulting in unstable water quality indicators of the dissolution solution. In particular, poor control of key indicators such as hardness and conductivity will affect the operating load of the salt separation system and even cause scaling and blockage, forcing the system to be shut down for maintenance, thus affecting the smooth operation of the entire salt separation system. In addition, the amount of artificially dissolved salt is small and the dissolution speed is slow. There is currently no better pretreatment method, and there is a lot of on-site accumulation, which puts great pressure on environmental protection. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the present invention provides a pretreatment system and method for re-salting of zero-emission by-product miscellaneous salts, which crushes and screens the miscellaneous salts to remove impurities, and uses the condensate from the coal plant to promote dissolution and adjust the concentration of the salt solution so that the treated salt solution meets the requirements of subsequent salt separation membrane filtration.

[0007] The technical solution adopted to achieve the above-mentioned invention object is: In a first aspect of the present invention, a pretreatment system for re-salting salt with zero emission and by-product miscellaneous salt is provided, the pretreatment system comprising: The mixed salt crushing mechanism is used to roughly crush the mixed salt in the ton bags; The screening mechanism is used to screen the coarse broken products. Part of the screened products are sent to the primary dissolution mechanism, and the other part is sent back to the miscellaneous salt crushing mechanism; The initial dissolution mechanism is used to dissolve and precipitate the sieved salts to obtain a supernatant; Dissolution mechanism, fully dissolve and dilute the supernatant again; a filtering mechanism for filtering the solution obtained from the dissolving mechanism; The detection mechanism is arranged between the dissolution mechanism and the filtration mechanism, and is used to detect parameters such as the flow rate, conductivity and hardness of the solution; A conveying mechanism is set between each mechanism to convey the miscellaneous salt materials.

[0008] Specifically, the miscellaneous salt crushing mechanism, screening mechanism, initial dissolution mechanism, dissolution mechanism and filtration mechanism are arranged in sequence; the miscellaneous salt crushing mechanism, screening mechanism and initial dissolution mechanism are connected by a belt conveyor, and the initial dissolution mechanism, dissolution mechanism and filtration mechanism are connected by pipelines.

[0009] In one embodiment of the present invention, the miscellaneous salt crushing mechanism includes a silo, a bag breaker and an arch breaker located in the silo. The bag breaker is located above the arch breaker and is used to break the ton bag, so that the miscellaneous salt in the ton bag falls into the silo, and then the arch breaker is used to coarsely crush the large pieces of material, with a target particle size of 40-60 mm.

[0010] In one embodiment of the present invention, the screening mechanism is a vibrating screen equipped with a 40-60 mm screen; a crusher is provided below the outlet of the vibrating screen.

[0011] In one embodiment of the present invention, the initial dissolution mechanism is an initial dissolution tank, which includes a tank body, a baffle arranged in the tank body, and a filter arranged on the top of the baffle.

[0012] In a typical embodiment, two baffles are installed in the primary dissolution tank, dividing it into three sections. The baffles are all lower than the tank body. The first baffle, located near the source of the impurities, is higher than the second baffle, located near the destination of the impurities. The filter mesh at the top of the first baffle has a pore size of 5 mm, while the filter mesh at the top of the second baffle has a pore size of 1 mm.

[0013] The first section of the primary dissolution tank is provided with a dissolution-aiding mechanism, including a condensate system and an aeration system; the condensate system includes a discharge device located in the primary dissolution tank, which is connected to the condensate source through a condensate pipeline. The discharge device structure includes a discharge main pipe connected to the condensate pipeline, and a plurality of discharge branch pipes connected to the discharge main pipe and arranged on the discharge main pipe, and discharge holes are evenly arranged on the discharge branch pipes; the aeration system includes an aeration device, which is connected to the compressed air source through a gas pipeline. The aeration device includes an aeration main pipe connected to the gas pipeline, and a plurality of aeration branch pipes connected to the aeration main pipe and arranged on the aeration main pipe, and aeration holes are evenly arranged on the aeration branch pipes.

[0014] In one or more embodiments of the present invention, the dissolution mechanism is a dissolution tank, which is equipped with a condensation system and an aeration system to fully dissolve and dilute the supernatant after treatment in the primary dissolution tank. The dissolution tank has a large volume and can be located below ground level to save space.

[0015] In one or more embodiments of the present invention, the filtration mechanism includes a sand filter and a safety filter, and a self-priming pump is provided between the dissolution tank and the sand filter.

[0016] The outlet of the self-priming pump is equipped with a flow meter, conductivity meter and hardness meter.

[0017] The safety filter is provided with a filter element. The water discharged from the safety filter enters the salt separation device.

[0018] In one or more embodiments of the present invention, a pretreatment method for re-salting by-product salts with zero emission is provided, comprising the following steps: S1: A forklift transports a ton bag filled with miscellaneous salt to the driving area. The driving crane lifts the ton bag to the top of the silo. The bag breaker installed on the top of the silo automatically breaks the ton bag, and the miscellaneous salt in the ton bag falls into the silo. The arch breaker in the silo coarsely breaks the bulk material to a target particle size of 40-60mm. In S2, the quantitative screw conveyor at the bottom of the silo quantitatively sends the coarsely crushed miscellaneous salt to the belt conveyor, which is then transported to the vibrating screen for screening. The vibrating screen sends the miscellaneous salt larger than 60mm to the coarse material trough. The coarse material trough is covered with a ton bag. After the ton bag is full, it is transported to the driving area by a forklift and then lifted to the upper part of the silo by the driving for secondary crushing; the miscellaneous salt smaller than 60mm enters the lower crusher, where the material is crushed to a particle size of less than 10mm and sent to the primary dissolution tank by a belt conveyor. The condensation system and aeration system set in the first section of the primary dissolution tank help the miscellaneous salt to be fully dissolved to obtain the dissolved concentrated brine. After two-stage precipitation in the primary dissolution tank, debris such as ton bags are intercepted on the filter screen, and the supernatant enters the dissolution tank; S3, the condensate system and aeration system in the dissolution tank are fully dissolved and diluted again; then, the condensate is sent to the sand filter by a self-priming pump. The outlet of the self-priming pump is equipped with a flow meter, conductivity meter and hardness meter. According to the test results, the amount of condensate added and the output volume of the self-priming pump can be adjusted to ensure that the salt solution meets the index requirements of the salt separation device; S4, the salt solution passes through the sand filter to reach the effluent turbidity ≤1NTU, the effluent from the sand filter enters the safety filter, and the effluent from the safety filter enters the salt separation device.

[0019] In summary, the present invention has the following beneficial effects: 1. The present invention provides a zero-emission by-product salt re-salting pretreatment system, which can effectively treat and dissolve the coal plant salt, meet the water inlet index requirements of the salt separation device, reduce the load on the filter membrane in the salt separation device, avoid scaling and clogging, and improve the salt separation treatment efficiency; 2. The present invention provides a pretreatment method for re-salting of miscellaneous salts with zero emission of by-products. The method is based on the condensate source of the coal plant as a source of hot water to promote the full dissolution and dilution of the salt; the aeration mechanism further promotes the dissolution of the salt, thereby improving the pretreatment efficiency and reducing the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0021] Figure 1 It is a schematic diagram of the present invention.

[0022] Figure 2 This is a top view of the aeration system in the primary dissolution tank and the dissolution tank.

[0023] Figure 3 It is a top view of the condensate system in the primary dissolution tank and the dissolution tank.

[0024] Figure 4 This is a schematic diagram of the first partition in the primary dissolution tank.

[0025] Figure 5 This is a schematic diagram of the second partition in the primary dissolution tank.

[0026] Figure 6 This is an overhead view of the primary dissolution pool.

[0027] In the figure: 1. Forklift; 2. Ton bag; 3. Driving; 4. Silo; 5. Bag breaker; 6. Arch breaker; 7. Dosing screw conveyor; 8. Belt conveyor; 9. Vibrating screen; 10. Coarse material trough; 11. Pulverizer; 12. Primary dissolution tank; 13. Condensate system; 14. Aeration system; 15. Dissolution tank; 16. Self-priming pump; 17. Flow meter; 18. Conductivity meter; 19. Hardness tester; 20. Sand filter; 21. Safety filter; 22. Drain branch; 23. Aeration branch; 24. First filter screen; 25. First baffle; 26. Second filter screen; 27. Second baffle; 28. Drain valve. DETAILED DESCRIPTION

[0028] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0029] In order to solve the problem in the prior art that the salt separation treatment load of impure salts is large and affects the membrane filtration efficiency, the present application provides a pretreatment system and treatment method for re-salting impure salts with zero emission and by-product.

[0030] Example 1: A pretreatment system for re-salting salt with zero emission and by-product like Figures 1 to 6 As shown, it includes a forklift 1, a ton bag 2, a crane 3, a silo 4, a bag breaker 5, a arch breaker 6, a quantitative screw conveyor 7, a belt conveyor 8, a vibrating screen 9, a coarse material trough 10, a crusher 11, a primary dissolution tank 12, a condensate system 13, an aeration system 14, a dissolution tank 15, a self-priming pump 16, a flow meter 17, a conductivity meter 18, a hardness tester 19, a sand filter 20, and a security filter 21.

[0031] The crane 3 is arranged above the silo 4. The silo 4 is provided with a bag breaker 5 and a breaker 6. The bag breaker 5 is located above the breaker 6. The bag breaker 5 structure includes a number of blades arranged along the driving direction. The crane 3 drives the ton bag 2 to move forward and is cut open by the blades. The ton bag 2 filled with miscellaneous salt is pressed on the bag breaker 5 under the action of its own gravity. The bag breaker breaks the ton bag, and the miscellaneous salt in the ton bag 2 falls into the silo 4. The breaker 6 then coarsely breaks the bulk material, with a target particle size of 40-60mm. The breaker 6 includes a stirring paddle structure that beats and disperses the material to achieve coarse material breaking. Below the stirring paddle structure is a quantitative screw conveyor 7, which outputs the coarsely broken material to the belt conveyor 8 and then transmits it to the vibrating screen for screening.

[0032] The vibrating screen 9 is equipped with a 40-60 mm screen.

[0033] A crusher is provided below the lower outlet of the vibrating screen 9. The rear of the crusher is connected to the primary dissolving tank 12 via a belt conveyor 8.

[0034] A coarse material trough 10 is located on the side of the vibrating screen. This trough is lined with ton bags. Once filled, the ton bags are transported to the driving area by forklift, where they are lifted to the upper part of the silo for secondary crushing. The debris larger than 40-60 mm on the upper layer of the vibrating screen is sent to the coarse material trough 10 on the side of the vibrating screen.

[0035] Initial dissolution tank, structure as Figures 4-6 As shown, it includes a tank body, a baffle disposed within the tank body, and a filter disposed on top of the baffle. As a typical embodiment, two baffles are disposed in the primary dissolution tank, dividing the primary dissolution tank into three sections. The height of the first baffle 25, which is located near the source of the impurities, is higher than the height of the second baffle 27, which is located near the destination of the impurities. The heights of both baffles are lower than the height of the tank body. The aperture of the first filter 24 on top of the first baffle 25 is 5 mm, and the aperture of the second filter 26 on top of the second baffle 27 is 1 mm. A drain pipe and a drain valve 28 are respectively disposed behind each section of the primary dissolution tank.

[0036] The first section of the primary dissolution tank is provided with a dissolution aid mechanism, including a condensation system 13 and an aeration system; the condensation system 13 includes a discharge device located in the primary dissolution tank, the discharge device is connected to the condensation source through a condensation pipeline, and the discharge device structure is as follows Figure 2 As shown, it includes a main drain pipe connected to the condensate pipeline, and a plurality of drain branches 22 connected to the main drain pipe and arranged on the main drain pipe. The drain branches 22 are evenly provided with drain holes. The aeration system includes an aeration device, which is connected to a compressed air source through a gas pipeline. The structure of the aeration device is as shown in FIG. Figure 3 As shown, it includes an aeration main pipe connected to a gas pipeline, and a plurality of aeration branch pipes 23 connected to the aeration main pipe and arranged on the aeration main pipe, and aeration holes are evenly arranged on the aeration branch pipes 23.

[0037] Dissolution tank 15 is equipped with a condensation system and aeration system similar to those in the primary dissolution tank, ensuring that the supernatant liquid after treatment in the primary dissolution tank is fully dissolved and diluted again. The dissolution tank has a large capacity and can be located below ground level to save space. The size and layout of the condensation system and aeration system in dissolution tank 15 are expanded according to the capacity of the dissolution tank.

[0038] The source of the condensate can be the whole plant process condensate (118℃) or vaporized condensate (150℃). The whole plant process condensate comes from the condensate generated by low-grade steam users of various devices such as the distillation tower reboiler, multi-effect evaporator, and heat exchange station; the vaporized condensate comes from the condensate generated by the sub-high-pressure steam users of each device and some steam heating.

[0039] A self-priming pump 16 is provided between the dissolving tank 15 and the sand filter 20. The sand filter 20 is filled with multiple layers of quartz sand of different particle sizes.

[0040] The outlet of the self-priming pump 16 is provided with a flow meter 17, a conductivity meter 18 and a hardness meter 19. The safety filter 21 is equipped with a 5μm large flow filter element. The water outlet of the safety filter 21 enters the salt separation device.

[0041] In one or more embodiments of the present invention, a pretreatment method for re-salting by-product salts with zero emission is provided, comprising the following steps: S1: A forklift transports a ton bag filled with miscellaneous salt to the driving area. The driving crane lifts the ton bag to the top of the silo. The bag breaker installed on the top of the silo automatically breaks the ton bag, and the miscellaneous salt in the ton bag falls into the silo. The arch breaker in the silo coarsely breaks the bulk material to a target particle size of 40-60mm. S2, the quantitative screw conveyor at the bottom of the silo quantitatively sends the coarsely broken salt to the belt conveyor, which is then transported to the vibrating screen for screening. The vibrating screen sends the salt larger than 60mm to the coarse material trough. The coarse material trough is covered with a ton bag. After the ton bag is full, it is transported to the driving area by a forklift and then lifted to the upper part of the silo by the driving for secondary crushing; the salt smaller than 60mm enters the lower crusher, and the material is crushed to a particle size of less than 10mm and sent to the primary dissolution tank by a belt conveyor. The condensation system and aeration system set in the first section of the primary dissolution tank help the salt to be fully dissolved to obtain the dissolved concentrated brine. After two-stage precipitation in the primary dissolution tank, debris such as ton bags are intercepted on the filter screen, and the supernatant enters the dissolution tank through the pipeline; S3, the condensate system and aeration system in the dissolution tank are fully dissolved and diluted again; then, the condensate is sent to the sand filter by a self-priming pump. The outlet of the self-priming pump is equipped with a flow meter, conductivity meter and hardness meter. According to the test results, the amount of condensate added and the output volume of the self-priming pump can be adjusted to ensure that the salt solution meets the index requirements of the salt separation device; S4, the salt solution passes through the sand filter to reach the effluent turbidity ≤1NTU, the effluent from the sand filter enters the safety filter, and the effluent from the safety filter enters the salt separation device.

[0042] Example 2: A pretreatment method for re-salting salt with zero emission of by-products The wastewater from a coal chemical plant contains 82.88% sodium sulfate, 9.29% sodium chloride, and 7.83% other salts. Water and calcium and magnesium are 0% of the total.

[0043] The forklift 1 transports the ton bag 2 filled with miscellaneous salt to the driving area, and the driving 3 lifts the ton bag 2 to the upper part of the silo 4. The bag breaker 5 installed on the upper part of the silo 4 automatically breaks the ton bag 2, and the miscellaneous salt in the ton bag 2 falls into the silo 4. The silo 4 is equipped with a breaker 6 to coarsely break the bulk material to a particle size of 40-60mm. The quantitative screw conveyor 7 at the bottom quantitatively feeds the miscellaneous salt to the belt conveyor 7, and the belt conveyor 7 transmits it to the vibrating screen 8 for screening. The vibrating screen 8 is loaded There is a 60mm screen. The debris larger than 60mm is sent to the coarse material tank 10. The coarse material tank 10 is lined with a ton bag 2. After the ton bag 2 is full, it is transported to the driving area by a forklift 1. It is lifted to the upper part of the silo 4 by the driving crane 3 for secondary crushing. The debris smaller than 60mm enters the lower crusher 11 and crushes the material to less than 10mm. It is sent to the primary dissolution tank 12 by a belt conveyor. The first section of the primary dissolution tank 12 is equipped with a condensation system 13 and an aeration system 14. The debris is filled The solution is dissolved in two stages. A high baffle 25, a low baffle 27 and three drain valves 28 are set at the bottom of the primary dissolution tank 12. When cleaning, debris and sewage are discharged from the drain valve 28. A filter screen is set on the top, which is a 5mm large-pore filter screen 24 and a 1mm small-pore filter screen 26. The dissolved concentrated brine undergoes two-stage precipitation. The debris is intercepted on the filter screen and the supernatant enters the dissolution tank 15. The dissolution tank is equipped with a condensation system 13 and an aeration system 14 for full dissolution and dilution again. The self-priming pump 16 delivers the water to the sand filter 20. The outlet of the self-priming pump 16 is equipped with a flow meter 17, a conductivity meter 18 and a hardness tester 19. The amount of condensate added and the delivery volume of the self-priming pump 16 can be adjusted according to the index requirements of the salt separation device. The sand filter 20 is filled with multiple layers of quartz sand of different particle sizes. The turbidity of the outlet water is ≤1NTU. The outlet water of the sand filter 20 enters the security filter 21, which is equipped with a 5μm large flow filter element. The outlet water of the security filter 21 enters the salt separation device.

[0044] This system achieves efficient salt dissolution. After dissolution, the conductivity is 48,000-60,000 μS / cm and the hardness is 0 mg / L. Impurities in the salt are primarily removed physically. Using this device, approximately 10.5 tons of salt can be dissolved daily, with approximately 140-160 tons of condensate recycled. Without this device, salt dissolution is slow, reaching approximately 1.5 tons per day. However, the salt solution contains excessive impurities, causing severe membrane clogging and inoperability. The water quality does not meet the inlet requirements of the nanofiltration membrane.

[0045] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A zero-emission by-product salt re-salting pretreatment system, characterized in that: The pretreatment system comprises: The mixed salt crushing mechanism is used to roughly crush the mixed salt in the ton bags; The screening mechanism is used to screen the coarse broken products. Part of the screened products are sent to the primary dissolution mechanism, and the other part is sent back to the miscellaneous salt crushing mechanism; The initial dissolution mechanism is used to dissolve and precipitate the sieved salts to obtain a supernatant; Dissolution mechanism, fully dissolve and dilute the supernatant again; a filtering mechanism for filtering the solution obtained from the dissolving mechanism; The detection mechanism is arranged between the dissolution mechanism and the filtration mechanism, and is used to detect the flow rate, conductivity and hardness parameters of the solution; The miscellaneous salt crushing mechanism, screening mechanism, initial dissolution mechanism, dissolution mechanism and filtration mechanism are arranged in sequence; the miscellaneous salt crushing mechanism, screening mechanism and initial dissolution mechanism are connected by a belt conveyor, and the initial dissolution mechanism, dissolution mechanism and filtration mechanism are connected by pipelines.

2. The zero-emission by-product salt re-salting pretreatment system according to claim 1 is characterized in that: The miscellaneous salt crushing mechanism includes a silo, a bag breaker and an arch breaker located in the silo. The bag breaker is located above the arch breaker and is used to break the ton bag, so that the miscellaneous salt in the ton bag falls into the silo, and then the arch breaker is used to coarsely crush the large pieces of material, with a target particle size of 40-60mm.

3. The zero-emission by-product salt re-salting pretreatment system according to claim 1 is characterized in that: The screening mechanism is a vibrating screen equipped with a 40-60 mm screen; a crusher is arranged below the lower outlet of the vibrating screen.

4. The zero-emission by-product salt re-salting pretreatment system according to claim 1 is characterized in that: The initial dissolution mechanism is an initial dissolution tank, which includes a tank body, a baffle arranged in the tank body, and a filter screen arranged on the top of the baffle.

5. The zero-emission by-product salt re-salting pretreatment system according to claim 4 is characterized in that: Two baffles are set in the primary dissolution tank to divide the primary dissolution tank into three sections. The height of the baffles is lower than the height of the tank body. The height of the first baffle close to the source of the impurities is higher than the height of the second baffle close to the destination of the impurities; the filter aperture at the top of the first baffle is larger than the filter aperture at the top of the second baffle.

6. The zero-emission by-product salt re-salting pretreatment system according to claim 5 is characterized in that: The first section of the primary dissolution tank is provided with a dissolution-aiding mechanism, including a condensate system and an aeration system; the condensate system includes a discharge device located in the primary dissolution tank, the discharge device is connected to the condensate source through a condensate pipeline, the discharge device includes a discharge main pipe connected to the condensate pipeline, and a plurality of discharge branches connected to the discharge main pipe and arranged on the discharge main pipe, and discharge holes are evenly arranged on the discharge branches; the aeration system includes an aeration device, the aeration device is connected to the compressed air source through a gas pipeline, the aeration device includes an aeration main pipe connected to the gas pipeline, and a plurality of aeration branches connected to the aeration main pipe and arranged on the aeration main pipe, and aeration holes are evenly arranged on the aeration branch pipes.

7. The zero-emission by-product salt re-salting pretreatment system according to claim 1 is characterized in that: The dissolution mechanism is a dissolution tank, in which a condensation system and an aeration system are arranged, so that the supernatant after the initial dissolution tank treatment is fully dissolved and diluted again.

8. The zero-emission by-product salt re-salting pretreatment system according to claim 7 is characterized in that: The filtration mechanism includes a sand filter and a safety filter, and a self-priming pump is arranged between the dissolution tank and the sand filter.

9. The zero-emission by-product salt re-salting pretreatment system according to claim 8, characterized in that: The outlet of the self-priming pump is equipped with a flow meter, conductivity meter and hardness meter.

10. A pretreatment method for re-salting salt with zero emission of by-products, characterized in that: The steps include: S1: A forklift transports a ton bag filled with miscellaneous salt to the driving area. The driving crane lifts the ton bag to the top of the silo. The bag breaker installed on the top of the silo automatically breaks the ton bag, and the miscellaneous salt in the ton bag falls into the silo. The arch breaker in the silo coarsely breaks the bulk material to a target particle size of 40-60mm. In S2, the quantitative screw conveyor at the bottom of the silo quantitatively sends the coarsely crushed miscellaneous salt to the belt conveyor, which is then transported to the vibrating screen for screening. The vibrating screen sends the miscellaneous salt larger than 60 mm to the coarse material trough located on the side of the vibrating screen. The coarse material trough is covered with a ton bag. After the ton bag is full, it is transported to the driving area by a forklift and then lifted to the upper part of the silo by the driving for secondary crushing; the miscellaneous salt smaller than 60 mm enters the lower crusher, and the material is crushed to a particle size of less than 10 mm and sent to the primary dissolution tank by a belt conveyor. The condensation system and aeration system set in the first section of the primary dissolution tank help the miscellaneous salt to be fully dissolved to obtain the dissolved concentrated brine. After two-stage precipitation in the primary dissolution tank, the debris is intercepted on the filter screen, and the supernatant enters the dissolution tank; In step S3, the condensate system and aeration system in the dissolution tank are fully dissolved and diluted again; then, the condensate is pumped to the sand filter by a self-priming pump. The outlet of the self-priming pump is equipped with a flow meter, conductivity meter, and hardness meter. Based on the test results, the amount of condensate added and the amount of self-priming pump output are adjusted to ensure that the salt solution meets the index requirements of the salt separation device; S4, the salt solution passes through the sand filter to reach the effluent turbidity ≤1NTU, the effluent from the sand filter enters the safety filter, and the effluent from the safety filter enters the salt separation device.

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