Nitric acid wastewater treatment system containing aluminum nitrate and treatment method thereof

Abstract

The invention discloses a nitric acid wastewater treatment system containing aluminum nitrate, including a two-stage column separation system and an aluminum sulfate purification system, wherein the aluminum sulfate purification system includes an aluminum sulfate feed tank, a preheater, a two-effect three-stage falling film evaporator for multiple evaporation and concentration of aluminum sulfate solution, a cooling crystallization tank, a crystallization transfer tank, a filter press, a high-level tank for receiving solids after filter pressing, and a scraper; the aluminum sulfate feed tank is connected to the aluminum sulfate solution tank. The nitric acid wastewater treatment method containing aluminum nitrate based on the wastewater treatment system has a small evaporation amount and a low production risk; the replacement is thorough, and the nitric acid content in the aluminum sulfate solution is obtained to be less, and aluminum sulfate that is better than the national standard can be further produced; the process of the invention is more energy-saving, the obtained aluminum sulfate product is of higher quality, and the overall temperature is not too high, which is conducive to long-term stable operation.

Description

Technical Field

[0001] The invention relates to the technical field of waste acid treatment, and in particular to a nitric acid wastewater treatment system containing aluminum nitrate and a treatment method thereof. Background Art

[0002] The corrosion process in the production of electrode foil requires a large amount of mixed acid, which produces a large amount of strong acid wastewater. One of the main wastewaters is aluminum nitric acid wastewater. The general treatment method is to directly neutralize it before discharging. Although it can greatly reduce the acidity, it contains a large amount of NO3 - 、Al 3+ Still existing in ionic state, it will cause total nitrogen, serious excess and waste of resources, which does not meet environmental protection requirements. Chinese patent document (application number 201711286050.0) discloses a method for treating aluminum-containing nitric acid wastewater, including the steps of: treating aluminum-containing nitric acid wastewater with multiple-effect evaporation to obtain a concentrated solution; treating the concentrated solution with cooling crystallization to obtain a crystallized solution; performing solid-liquid separation on the crystallized solution to obtain a filtrate and crystalline aluminum nitrate; recycling the filtrate, dissolving the crystalline aluminum nitrate, and adding sulfuric acid for replacement treatment to obtain nitric acid and aluminum sulfate; during the cooling crystallization process, adding nitric acid with a concentration of 10-11 mol / L to the concentrated solution, and the volume ratio of the added nitric acid to the concentrated solution is (1.3-1.5):1.

[0003] However, the prior art has the following disadvantages:

[0004] The amount to be evaporated is large, and hydrated aluminum nitrate decomposes at 135 degrees. Three-effect evaporation is used. Since the solubility of aluminum nitrate changes greatly with temperature, the final effect temperature cannot be too low, so the first effect temperature is relatively high, and the production risk is relatively high;

[0005] The separated aluminum nitrate can be replaced by adding sulfuric acid, but the replacement is incomplete. The obtained aluminum sulfate contains more nitric acid, and the residual sulfuric acid is not treated, resulting in waste of nitric acid and impure aluminum sulfate. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the deficiencies in the above-mentioned prior art and provide a nitric acid wastewater treatment system containing aluminum nitrate and a treatment method thereof.

[0007] The technical solution adopted by the present invention to solve the technical problem is:

[0008] A nitric acid wastewater treatment system containing aluminum nitrate, comprising:

[0009] A two-stage column separation system, which is used to separate aluminum ions from nitric acid wastewater containing aluminum nitrate, comprises at least three resin columns and a series of pipelines having the same number as the resin columns, wherein the top of the resin column is provided with an upper series interface, a feed port, a compressed air inlet, a cleaning water inlet and a sulfuric acid inlet in parallel, and the bottom of the resin column is provided with a lower series interface, an aluminum sulfate solution outlet, a nitric acid waste liquid outlet and a nitric acid wastewater outlet containing aluminum nitrate in parallel; the resin columns are sequentially connected in series through the series pipelines connected between the lower series interface and the upper series interface to form a loop;

[0010] An aluminum nitrate tank, wherein the aluminum nitrate tank is provided with a liquid outlet connected to the feed port, and is used to introduce the pretreated nitric acid wastewater containing aluminum nitrate into the resin column; the aluminum nitrate tank is also provided with a liquid return port connected to the nitric acid wastewater outlet containing aluminum nitrate, and is used to receive the nitric acid wastewater containing aluminum nitrate after reaching saturation in the resin column;

[0011] A compressed air pipeline connected to the compressed air inlet is used to introduce compressed air into the resin column; a washing water tank connected to the washing water inlet is used to provide washing water to the resin column; a sulfuric acid tank connected to the sulfuric acid inlet is used to provide sulfuric acid solution for aluminum ion desorption to the resin column; an aluminum sulfate solution tank connected to the aluminum sulfate solution outlet is used to receive the aluminum sulfate solution discharged from the resin column; and a reuse nitric acid tank connected to the nitric acid waste liquid outlet is also included, which is used to receive the nitric acid waste liquid discharged after aluminum adsorption by the two-stage column separation system;

[0012] It also includes an aluminum sulfate purification system, which includes an aluminum sulfate feed tank, a preheater, a two-effect three-stage falling film evaporator for multiple evaporation and concentration of aluminum sulfate solution, a cooling crystallization tank, a crystallization transfer tank, a filter press, a high-level tank for receiving solids after filter pressing, and a scraper machine, which are connected in sequence; the aluminum sulfate feed tank is connected to the aluminum sulfate solution tank.

[0013] Furthermore, there are four resin columns, namely, column A, column B, column C and column D, and there are four series pipelines, namely, the A series pipeline for connecting the lower series interface of column A with the upper series connection port of column B, the B series pipeline for connecting the lower series interface of column B with the upper series connection port of column C, the C series pipeline for connecting the lower series interface of column C with the upper series connection port of column D, and the D series pipeline for connecting the lower series interface of column D with the upper series connection port of column A.

[0014] Furthermore, it also includes a reuse nitric acid tank connected to the nitric acid waste liquid outlet, and the lower end of the resin column is also provided with a dilute nitric acid outlet in parallel, and the dilute nitric acid outlet is connected to a dilute nitric acid tank for receiving the dilute nitric acid discharged by water replacement before aluminum ion desorption in the resin column; the dilute nitric acid tank is also connected to the cleaning water inlet of the resin column, and is used to pass dilute nitric acid into the resin column for replacement. The purpose of replacement with dilute nitric acid is to reduce the amount of washing water, increase the nitric acid content in the dilute nitric acid, and then use it to prepare nitric acid to reduce the loss of nitric acid. If it is directly replaced with water, the nitric acid concentration in the washing water is too low, and the amount of washing water generated is too much. So much water cannot be used for preparing nitric acid in the front, which also leads to waste of nitric acid.

[0015] Furthermore, a dilute sulfuric acid outlet is provided in parallel at the lower end of the resin column, and the dilute sulfuric acid outlet is connected to a dilute sulfuric acid tank for receiving the dilute sulfuric acid discharged from the resin column after water displacement after aluminum ion desorption; the dilute sulfuric acid tank is connected to the cleaning water inlet of the resin column, and is used to pass dilute sulfuric acid into the resin column for displacement, and the dilute sulfuric acid is still placed in the dilute sulfuric acid tank after displacement.

[0016] Further, the bottom of the resin column is provided with a sulfuric acid outlet in parallel, and the sulfuric acid outlet is connected to a sulfuric acid tank. When the aluminum ion in the resin column is nearly completely resolved (when the aluminum ion concentration detected at the outlet of the aluminum sulfate solution is close to 0), the resin column is basically sulfuric acid, and this part of sulfuric acid is emptied into the sulfuric acid tank through the sulfuric acid outlet and used during the next resolution.

[0017] Further, the two-effect three-stage falling film evaporator comprises:

[0018] A single-effect falling film evaporator is used to perform a single-effect falling film evaporation on the aluminum sulfate solution preheated from the preheater to form a single-effect concentrated solution;

[0019] The two-effect falling film evaporator is used to perform two-effect falling film evaporation on the first-effect concentrated liquid from the first-effect falling film evaporator to form a second-effect concentrated liquid;

[0020] The three-stage falling film evaporator is used to perform three-effect falling film evaporation on the second-effect concentrated liquid from the two-effect falling film evaporator to form a three-effect concentrated liquid;

[0021] The single-effect falling film evaporator is provided with a single-effect secondary steam outlet, which is connected to the second-effect falling film evaporator through a pipeline, and is used to send the secondary steam generated by the single-effect falling film evaporator into the second-effect falling film evaporator, and is used as the heat exchange medium of the second-effect falling film evaporator; and also includes a steam pipeline, which is respectively connected to the steam inlet of the single-effect falling film evaporator and the three-stage falling film evaporator, and is used as the heat exchange medium of the single-effect falling film evaporator and the three-stage falling film evaporator.

[0022] Specifically, the single-effect falling film evaporator comprises a single-effect falling film heat exchanger, a single-effect circulation pipeline, a single-effect circulation pump arranged on the single-effect circulation pipeline and a single-effect falling film evaporation chamber, the preheater is connected with the top of the tube side of the single-effect falling film heat exchanger through a pipeline, the bottom of the tube side of the single-effect falling film heat exchanger is connected with the lower end of the single-effect falling film evaporation chamber, the upper end of the tube side of the single-effect falling film heat exchanger is connected with the bottom end of the single-effect falling film evaporation chamber through a second-effect circulation pipeline, and the top of the single-effect falling film evaporation chamber is provided with the single-effect secondary steam outlet;

[0023] The two-effect falling film evaporator comprises a two-effect falling film heat exchanger, a two-effect circulation pipeline, a two-effect circulation pump arranged on the two-effect circulation pipeline and a two-effect falling film evaporation chamber, the lower end of the two-effect falling film evaporation chamber is connected with the bottom end of the tube side of the two-effect falling film heat exchanger, the upper end of the tube side of the two-effect falling film heat exchanger is connected with the bottom end of the two-effect falling film evaporation chamber through the two-effect circulation pipeline, the lower end of the one-effect falling film evaporation chamber is connected with the upper end of the tube side of the two-effect falling film heat exchanger, and the top of the two-effect falling film evaporation chamber is provided with a two-effect secondary steam outlet;

[0024] The three-stage falling film evaporator comprises a three-effect falling film heat exchanger, a three-effect circulation pipeline, a three-effect circulation pump arranged on the three-effect circulation pipeline and a three-effect falling film evaporation chamber, the lower end of the three-effect falling film evaporation chamber is connected with the bottom end of the tube side of the three-effect falling film heat exchanger, the upper end of the tube side of the three-effect falling film heat exchanger is connected with the bottom end of the three-effect falling film evaporation chamber through the three-effect circulation pipeline, the lower end of the second-effect falling film evaporation chamber is connected with the upper end of the tube side of the three-effect falling film heat exchanger, and the top of the three-effect falling film evaporation chamber is provided with a three-effect secondary steam outlet.

[0025] More specifically, the aluminum sulfate purification system also includes a first condensed water tank and a second condensed water tank. The first condensed water tank is used to receive the secondary steam generated by the second-effect falling film evaporation chamber and the third-effect falling film evaporation chamber and the condensed water generated in the shell of the second-effect falling film heat exchanger. The second condensed water tank is used to receive the condensed water generated in the shell of the first-effect falling film heat exchanger and the shell of the third-effect falling film heat exchanger.

[0026] Furthermore, the second condensed water tank is connected to the preheater and is used to pass condensed water into the preheater as a heat exchange medium for the aluminum sulfate solution.

[0027] In order to maintain the normal pressure state of the high-pressure pipe and avoid overpressure, a first heat exchanger is preferably included, wherein the tube side inlet and tube side outlet of the first heat exchanger are connected to the high-level tank for condensing the hot steam generated by the reflux high-level tank.

[0028] A method for treating nitric acid wastewater containing aluminum nitrate, the method adopting the above-mentioned nitric acid wastewater treatment system containing aluminum nitrate, comprising the following steps:

[0029] Step 1, the nitric acid wastewater containing aluminum nitrate in the aluminum nitrate tank is pumped to a two-stage column separation system, one of the resin columns in the two-stage column separation system is used as a primary column, the resin column connected with the lower serial interface of the primary column is used as a secondary column, the resin column connected with the lower serial interface of the secondary column is used as a tertiary column, the nitric acid wastewater containing aluminum nitrate enters through the feed port of the primary column, flows out from the lower serial interface of the primary column and enters the feed port of the secondary column, and then flows out from the lower port of the secondary column into the reuse nitric acid tank; when the aluminum content in the effluent of the lower serial interface of the primary column is close to the aluminum content in the nitric acid wastewater containing aluminum nitrate, the series pipeline for connecting the lower serial interface of the primary column and the upper serial interface of the secondary column is closed, the liquid in the primary column is returned to the aluminum nitrate tank, after being dried, it is repeatedly cleaned and dried, and then sulfuric acid with a mass concentration of 20-30% is introduced to parse out aluminum ions, and after the parsing is completed, it is placed in an aluminum sulfate solution tank, dried, and repeatedly cleaned and dried for standby use;

[0030] Step 3, the aluminum sulfate solution introduced into the aluminum sulfate solution tank in step 1 is pumped to the aluminum sulfate feed tank, the aluminum sulfate solution is pressurized by the feed pump and then enters the heat exchanger to be preheated to 64±3°C, and then enters the two-effect three-stage falling film evaporator for evaporation and concentration to obtain a concentrated solution, the concentrated solution enters the cooling crystallization tank through a delivery pump, and enters the crystallization transfer tank after preliminary cooling and crystallization. After the aluminum sulfate is fully precipitated, it enters the filter press for filtration separation, the solid is put into the high-level tank, aluminum hydroxide is added to the high-level tank, the temperature is raised to neutralize the residual sulfuric acid, and after the neutralization is completed, the scraper is discharged or the aluminum sulfate solution is prepared for discharge.

[0031] Step three, simultaneously open the series pipelines for connecting the lower series interface of the secondary column and the upper series interface of the tertiary column, use the secondary column as a new primary column, use the tertiary column as a new secondary column, and use the resin column connected between the upper series interface and the lower series interface of the tertiary column as a new tertiary column, and repeat the above steps one and two until the column separation and analysis of the nitric acid wastewater containing aluminum nitrate is completed.

[0032] Furthermore, the specific method of repeatedly cleaning and drying the primary column before sulfuric acid analysis in step 1 is: first, the dilute nitric acid in the dilute nitric acid tank is pumped into the primary column through the cleaning water inlet for dilute nitric acid replacement, and after the replacement, all the dilute nitric acid is discharged into the dilute nitric acid tank, and then dried; then the water in the cleaning water tank is pumped into the primary column through the cleaning water inlet for water replacement, and after the replacement, all the water is discharged into the dilute nitric acid tank, and then dried.

[0033] The specific method of repeatedly cleaning and drying the primary column after sulfuric acid analysis in step 1 is as follows: first, the dilute sulfuric acid in the dilute sulfuric acid tank is pumped into the primary column through the cleaning water inlet for dilute sulfuric acid replacement, and after replacement, all the dilute sulfuric acid is discharged into the dilute sulfuric acid tank, and then dried; then, the water in the cleaning water tank is pumped into the primary column through the cleaning water inlet for water replacement, and after replacement, all the water is discharged into the dilute sulfuric acid tank, and then dried for standby use.

[0034] Furthermore, in step 3, the specific method for evaporating and concentrating the aluminum sulfate solution by the two-effect three-stage falling film evaporator is as follows: the aluminum sulfate solution first enters the tube side of the first-effect falling film heat exchanger, the material in the tube side of the first-effect falling film heat exchanger exchanges heat with the heating steam in the shell layer of the first-effect falling film heat exchanger to boil and evaporate, the water vapor generated by evaporation carries part of the droplets into the first-effect falling film evaporation chamber, and the droplets of water vapor are separated by the first-effect falling film evaporation chamber to form the secondary steam, the secondary steam enters the shell layer of the second-effect falling film heat exchanger, a part of the droplets separated by the first-effect falling film evaporation chamber is pumped back to the tube side of the first-effect falling film heat exchanger through the first-effect circulation pipeline to continue heating and concentrating, and the other part is the first-effect concentrated liquid, which is pumped to the tube side of the second-effect falling film heat exchanger, exchanges heat with the secondary steam in the shell layer of the second-effect falling film heat exchanger, and further evaporates, the water vapor generated by evaporation carries part of the droplets into the second-effect falling film evaporation chamber, After the droplets in the water vapor are separated by the second-effect falling film evaporation chamber, secondary steam is formed; part of the droplets separated by the second-effect falling film evaporation chamber is pumped back to the tube side of the second-effect falling film heat exchanger through the second-effect circulation pipeline for continuous heating and concentration, and the other part is the second-effect concentrated liquid, which is pumped to the tube side of the third-effect falling film heat exchanger, and heat-exchanged with the heating steam in the shell of the third-effect falling film heat exchanger for boiling and evaporation. The water vapor generated by evaporation carries part of the droplets into the third-effect falling film evaporation chamber, and the droplets in the water vapor are separated by the third-effect falling film evaporation chamber to form secondary steam, which enters the first condensation water tank together with the secondary steam discharged from the second-effect falling film evaporation chamber and the condensed water generated in the shell of the second-effect falling film heat exchanger, and the condensed water generated in the shell of the first-effect falling film heat exchanger and the third-effect falling film heat exchanger respectively flow into the second condensation water tank, and the condensed water in the second condensation water tank is finally pumped into the preheater and enters the V-01 condensation water tank after heat exchange with the aluminum sulfate solution.

[0035] The beneficial effects of the present invention are as follows: the nitric acid wastewater treatment system containing aluminum nitrate and the nitric acid wastewater treatment method containing aluminum nitrate based on the present invention have small evaporation amount and low production risk; the replacement is thorough, and the nitric acid content in the obtained aluminum sulfate solution is low; after separating aluminum, the present invention uses 20-30% sulfuric acid for analysis (20-30% sulfuric acid can be well analyzed, and the solubility of aluminum sulfate is the smallest when it is finally concentrated to 55-60%, which is convenient for fully taking out aluminum sulfate, and the amount required for evaporation is still small. A higher sulfuric acid concentration will damage the resin), and then the aluminum sulfate containing sulfuric acid is concentrated. When the sulfuric acid content reaches 55%-60%, the solubility of aluminum sulfate in 55%-60% sulfuric acid is the lowest. As long as the analyzed sulfuric acid is concentrated 2-3 times, separated by crystallization, and the remaining small amount of sulfuric acid is reacted, aluminum sulfate that is better than the national standard can be produced; the process of the present invention is more energy-saving, and the overall temperature is not too high, which is conducive to long-term stable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0037] Figure 1 It is a schematic diagram of a device for obtaining aluminum sulfate by column separation in a nitric acid wastewater treatment system containing aluminum nitrate according to the present invention.

[0038] Figure 2 for Figure 1 Schematic diagram of the two-stage column separation system.

[0039] Figure 3 It is a schematic diagram of the aluminum sulfate purification system in the nitric acid wastewater treatment system containing aluminum nitrate of the present invention.

[0040] Figure 4 for Figure 3 Schematic diagram of the crystallization purification system structure.

[0041] Figure 5 for Figure 3 Schematic diagram of the falling film evaporation system structure.

[0042] The reference numerals in the figure are: 1. sulfuric acid tank, 2. sulfuric acid pump, 3. cleaning water tank, 4. cleaning water pump, 5. aluminum nitrate tank, 6. aluminum nitrate pump, 7. recycled nitric acid tank, 8. recycled nitric acid pump, 9. dilute nitric acid tank, 10. dilute nitric acid pump, 11. Dilute sulfuric acid tank, 12. Dilute sulfuric acid pump, 13. Aluminum sulfate solution tank, 14. Aluminum sulfate raw material pump, 15. Second sulfuric acid tank, 16. Condensate pump, 17. V-09 tank, 18. Aluminum sulfate feed tank, 19. Feed pump, 20. First mother liquor pump, 21. High-level tank E, 22. High-level tank A / B, 23. High-level tank C / D, 24. Second mother liquor pump, 25. Crystallization transfer tank, 26. Scraper, 27. First filter press, 28. Second filter press, 29. First heat exchanger, 30. First cooling crystallization tank, 31. Second cooling crystallization tank, 32. Preheater, 33. First-effect falling film heat exchanger, 34. First-effect falling film evaporation chamber, 35. Second-effect falling film heat exchanger, 36. Second-effect falling film evaporation chamber, 37. Third-effect falling film heat exchanger, 38. Three-effect falling film evaporation chamber, 39. Second heat exchanger, 40. First effect circulation pump, 41. First condensed water tank, 42. Second effect circulation pump, 43. Three-effect circulation pump, 44. Second condensed water tank, 45. Vacuum pump, 46. Third heat exchanger, 47. V-01 condensed water tank;

[0043] Q1: Two-stage column separation system;

[0044] Q2: Crystallization purification system;

[0045] Q3: Falling film evaporation system. DETAILED DESCRIPTION

[0046] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams that only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention, and directions and references (e.g., up, down, left, right, etc.) may only be used to help describe the features in the drawings. Therefore, the following specific embodiments are not to be taken in a limiting sense, and the scope of the subject matter claimed is limited only by the attached claims and their equivalents.

[0047] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "set", and "provided with" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be internal communication between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood based on specific circumstances. Unless otherwise clearly specified and limited, the terms "pipeline", "pipeline", and "pipeline" should be understood in a broad sense. For example, it can be a simple pipe or a pipe and a control valve and / or flow meter and / or thermometer and / or pump arranged on the pipe as needed. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood based on specific circumstances.

[0048] See Figures 1 to 4 (the direction of the arrow in the figure is the direction of fluid flow), a nitric acid wastewater treatment system containing aluminum nitrate, including a two-stage column separation system, an aluminum nitrate tank, a compressed air pipeline, a cleaning water tank, a sulfuric acid tank, an aluminum sulfate solution tank and an aluminum sulfate purification system.

[0049] The two-stage column separation system is used to separate aluminum ions from nitric acid wastewater containing aluminum nitrate, and includes at least 3 resin columns and a series pipeline having the same number as the resin columns (it is also possible to pass without being connected in series, but the column passing efficiency will be reduced). The top of the resin column is provided with an upper series interface, a feed port, a compressed air inlet, a cleaning water inlet and a sulfuric acid inlet in parallel, and the bottom of the resin column is provided with a lower series interface, an aluminum sulfate solution outlet, a nitric acid waste liquid outlet and a nitric acid wastewater outlet containing aluminum nitrate in parallel; the resin columns are sequentially connected in series through the series pipeline connected between the lower series interface and the upper series interface to form a loop.

[0050] The specific number of resin columns and series pipelines can be adjusted according to actual engineering needs. In this embodiment, there are 4 resin columns and 4 series pipelines, specifically: there are 4 resin columns, namely column A, column B, column C and column D, and there are 4 series pipelines, namely, the A series pipeline for connecting the lower series interface of column A with the upper series connection port of column B, the B series pipeline for connecting the lower series interface of column B with the upper series connection port of column C, the C series pipeline for connecting the lower series interface of column C with the upper series connection port of column D, and the D series pipeline for connecting the lower series interface of column D with the upper series connection port of column A.

[0051] The aluminum nitrate tank is provided with a liquid outlet connected to the feed port, specifically connected through a pipeline provided with an aluminum nitrate pump PP-103A, B, for introducing pretreated nitric acid wastewater containing aluminum nitrate into the resin column. The aluminum nitrate tank is also provided with a liquid return port connected to the outlet of the nitric acid wastewater containing aluminum nitrate, for receiving the nitric acid wastewater containing aluminum nitrate after reaching saturation in the resin column.

[0052] The compressed air pipeline is connected to the compressed air inlet of the resin column for introducing compressed air into the resin column. The cleaning water tank is connected to the cleaning water inlet of the resin column for providing cleaning water into the resin column. The sulfuric acid tank is connected to the sulfuric acid inlet of the resin column for providing sulfuric acid solution for aluminum ion desorption into the resin column. The aluminum sulfate solution tank is connected to the aluminum sulfate solution outlet of the resin column for receiving the aluminum sulfate solution discharged from the resin column.

[0053] It also includes a reuse nitric acid tank connected to the nitric acid waste liquid outlet of the resin column. The lower end of the resin column is also provided with a dilute nitric acid outlet in parallel, and the dilute nitric acid outlet is connected to a dilute nitric acid tank for receiving the dilute nitric acid discharged by water replacement before aluminum ion desorption in the resin column. The dilute nitric acid tank is also connected to the cleaning water inlet of the resin column, and is used to pass dilute nitric acid into the resin column for replacement. The purpose of such a setting is that it is convenient to use dilute nitric acid to replace it first in the cleaning process before sulfuric acid resolves aluminum ions. The purpose of replacing with dilute nitric acid is to reduce the amount of washing water, increase the nitric acid content in dilute nitric acid, and then use it to prepare nitric acid to reduce the loss of nitric acid. If it is directly replaced with water, the nitric acid concentration in the washing water is too low, and the amount of washing water generated is too much. So much water cannot be used for preparing nitric acid in the front, which also leads to waste of nitric acid. After the dilute nitric acid is replaced, it is still put into the dilute nitric acid tank. Further, the lower end of the resin column is also provided with a dilute sulfuric acid outlet in parallel, and the dilute sulfuric acid outlet is connected to a dilute sulfuric acid tank for receiving the dilute sulfuric acid discharged by water replacement after aluminum ion desorption in the resin column. The dilute sulfuric acid tank is connected to the cleaning water inlet of the resin column, and is used to pass dilute sulfuric acid into the resin column for replacement. The purpose of such arrangement is that it is convenient to replace with dilute sulfuric acid first in the cleaning process after sulfuric acid resolves aluminum ions. The purpose of replacing with dilute sulfuric acid is to reduce the amount of wash water, increase the sulfuric acid content in dilute sulfuric acid, and then be used to prepare sulfuric acid for analysis, reducing the loss of sulfuric acid. If directly replaced with water, the sulfuric acid concentration in the wash water is too low, and the amount of wash water produced is too much, so much water cannot be used for preparing sulfuric acid in the front, which also leads to the waste of sulfuric acid. After the dilute nitric acid is replaced, the dilute sulfuric acid tank is still put in. The bottom of the resin column is provided with a sulfuric acid outlet in parallel, and the sulfuric acid outlet is connected to the sulfuric acid tank. When the aluminum ion in the resin column is nearly completely resolved (when the aluminum ion concentration is detected at the outlet of the aluminum sulfate solution and is close to 0), the resin column is basically sulfuric acid, and this part of sulfuric acid is emptied to the sulfuric acid tank through the sulfuric acid outlet, and is used during the next resolution.

[0054] The aluminum sulfate purification system includes an aluminum sulfate feed tank 18, a falling film evaporation system Q3, and a crystallization purification system Q2, which are sequentially connected along the direction of aluminum sulfate travel. The crystallization purification system Q2 includes a cooling crystallization tank (the cooling crystallization tank in this embodiment includes a first cooling crystallization tank 30 and a second cooling crystallization tank 31), a crystallization transfer tank 25, a second mother liquor pump 24, a filter press (the filter press in this embodiment includes a first filter press 26 and a second filter press 27), a high-level tank for receiving solids after pressure filtration, a first mother liquor pump 20, and a scraper 26; the aluminum sulfate feed tank 18 is connected to the aluminum sulfate solution tank 13, and the aluminum sulfate solution in the aluminum sulfate solution tank 13 is pumped to the aluminum sulfate feed tank 18 via the aluminum sulfate raw material pump 14 during operation.

[0055] The falling film evaporation system Q3 includes a preheater 32 connected in sequence along the traveling direction of the aluminum sulfate and a two-effect three-stage falling film evaporator for multiple evaporation and concentration of the aluminum sulfate solution.

[0056] Specifically, the two-effect three-stage falling film evaporator includes:

[0057] A single-effect falling film evaporator is used to perform a single-effect falling film evaporation on the aluminum sulfate solution preheated from the preheater to form a single-effect concentrated solution;

[0058] The two-effect falling film evaporator is used to perform two-effect falling film evaporation on the first-effect concentrated liquid from the first-effect falling film evaporator to form a second-effect concentrated liquid;

[0059] The three-stage falling film evaporator is used to perform three-effect falling film evaporation on the second-effect concentrated liquid from the two-effect falling film evaporator to form a three-effect concentrated liquid;

[0060] The single-effect falling film evaporator is provided with a single-effect secondary steam outlet, which is connected to the second-effect falling film evaporator through a pipeline, and is used to send the secondary steam generated by the single-effect falling film evaporator into the second-effect falling film evaporator, and is used as the heat exchange medium of the second-effect falling film evaporator; and also includes a steam pipeline, which is respectively connected to the steam inlet of the single-effect falling film evaporator and the three-stage falling film evaporator, and is used as the heat exchange medium of the single-effect falling film evaporator and the three-stage falling film evaporator.

[0061] More specifically: the single-effect falling film evaporator includes a single-effect falling film heat exchanger 33, a single-effect circulation pipeline, a single-effect circulation pump 40 arranged on the single-effect circulation pipeline and a single-effect falling film evaporation chamber 34. The single-effect circulation pipeline is also provided with two control valves and a flow meter, one of which is arranged on the side of the single-effect circulation pump 40 close to the single-effect falling film heat exchanger 33, and the other control valve is arranged on the side of the single-effect circulation pump 40 close to the single-effect falling film evaporation chamber. The preheater 32 is connected to the top of the tube side of the first-effect falling film heat exchanger 33 through a pipeline, and the bottom end of the tube side of the first-effect falling film heat exchanger 33 is connected to the lower end of the first-effect falling film evaporation chamber 34 (specifically, it is connected through a pipeline, one end of the pipeline is connected to the bottom end of the tube side of the first-effect falling film heat exchanger 33, and the other end of the pipeline is connected to the first-effect circulation pipeline, and the connection point is located between the first-effect circulation pump 40 and another control valve.), the upper end of the tube side of the first-effect falling film heat exchanger 33 is connected to the bottom end of the first-effect falling film evaporation chamber 34 through the first-effect circulation pipeline, and the top of the first-effect falling film evaporation chamber 33 is provided with the first-effect secondary steam outlet.

[0062] The two-effect falling film evaporator includes a two-effect falling film heat exchanger 35, a two-effect circulation pipeline, a two-effect circulation pump 42 arranged on the two-effect circulation pipeline and a two-effect falling film evaporation chamber 36. The two-effect circulation pipeline is also provided with two control valves and a flow meter, wherein one control valve and the flow meter are arranged on a side of the two-effect circulation pump 42 close to the two-effect falling film heat exchanger 35, and the other control valve is arranged on a side of the two-effect circulation pump 42 close to the two-effect falling film evaporation chamber 36. The lower end of the second-effect falling film evaporation chamber 36 is connected to the bottom end of the tube side of the second-effect falling film heat exchanger 35 (specifically, it is connected through a pipeline, one end of the pipeline is connected to the bottom end of the tube side of the second-effect falling film heat exchanger 35, and the other end of the pipeline is connected to the second-effect circulation pipeline, and the connection point is located between the second-effect circulation pump 42 and another control valve.), the upper end of the tube side of the second-effect falling film heat exchanger 35 is connected to the bottom end of the second-effect falling film evaporation chamber 36 through the second-effect circulation pipeline, the lower end of the first-effect falling film evaporation chamber 34 is connected to the upper end of the tube side of the second-effect falling film heat exchanger 35, and the top of the second-effect falling film evaporation chamber 36 is provided with a second-effect secondary steam outlet;

[0063] The three-stage falling film evaporator includes a three-effect falling film heat exchanger 37, a three-effect circulation pipeline, a three-effect circulation pump 43 arranged on the three-effect circulation pipeline and a three-effect falling film evaporation chamber 38. The three-effect circulation pipeline is also provided with two control valves and a flow meter, one of which is arranged on the side of the three-effect circulation pump 43 close to the three-effect falling film heat exchanger 37, and the other control valve is arranged on the side of the three-effect circulation pump 43 close to the three-effect falling film evaporation chamber 37. The lower end of the three-effect falling film evaporation chamber 38 is connected to the bottom end of the tube side of the three-effect falling film heat exchanger 37 (specifically, it is connected through a pipeline, one end of the pipeline is connected to the bottom end of the tube side of the three-effect falling film heat exchanger 37, and the other end of the pipeline is connected to the three-effect circulation pipeline, and the connection point is located between the three-effect circulation pump 43 and another control valve.), the upper end of the tube side of the three-effect falling film heat exchanger 37 is connected to the bottom end of the three-effect falling film evaporation chamber 38 through the three-effect circulation pipeline, and the lower end of the two-effect falling film evaporation chamber 36 is connected to the upper end of the tube side of the three-effect falling film heat exchanger 37 (specifically, the lower end of the two-effect falling film evaporation chamber 36 is connected to the three-effect circulation pipeline through a pipeline,), and the top of the three-effect falling film evaporation chamber 38 is provided with a three-effect secondary steam outlet.

[0064] Furthermore, the falling film evaporation system Q3 further includes a first condensed water tank 41 and a second condensed water tank 44, wherein the first condensed water tank 41 is used to receive the secondary steam generated by the second-effect falling film evaporation chamber 36 and the third-effect falling film evaporation chamber 38 and the condensed water generated in the shell of the second-effect falling film heat exchanger 35, and the second condensed water tank 44 is used to receive the condensed water generated in the shell of the first-effect falling film heat exchanger 33 and the shell of the third-effect falling film heat exchanger 37. The second condensed water tank 44 is connected to the preheater 32, and is used to pass the condensed water into the preheater 32 as a heat exchange medium for the aluminum sulfate solution, thereby heating the aluminum sulfate solution.

[0065] The specific materials and specifications of the two-effect three-stage falling film evaporator and preheater in this embodiment are as follows:

[0066] One-effect falling film heat exchanger 33 and one-effect falling film evaporation chamber 34

[0067]

[0068] Second-effect falling film heat exchanger 35 and second-effect falling film evaporation chamber 36

[0069]

[0070] Three-effect falling film heat exchanger 37 and three-effect falling film evaporation chamber 38

[0071]

[0072] Primary preheater

[0073]

[0074] Secondary preheater

[0075]

[0076] The design parameters of the nitric acid wastewater treatment method containing aluminum nitrate based on the above-mentioned nitric acid wastewater treatment system containing aluminum nitrate are as follows:

[0077] Nitric acid wastewater feed concentration containing aluminum nitrate: acidity 1.275 mol / L.

[0078] Feed temperature of nitric acid wastewater containing aluminum nitrate: 20℃

[0079] Feed rate of nitric acid wastewater containing aluminum nitrate: 10T / h

[0080] Evaporation rate of aluminum sulfate solution: 5.688T / h

[0081] Evaporation temperature of aluminum sulfate solution: 55-90℃ (gas phase temperature, 55℃ for second and third effect, 90℃ for first effect

[0082] Saturated solution boiling point rise: ≤46℃

[0083] Discharge state: Aluminum sulfate 18hydrate

[0084] Supplementary steam pressure: 0.1MPa

[0085] Supplementary steam flow: 3913Kg / Hr (can be determined by design)

[0086] Circulating cooling water inlet temperature: ≤32℃

[0087] Circulating cooling water return temperature: ≤37℃

[0088] Circulating cooling water inlet pressure: 0.2-0.5MPa

[0089] Circulating cooling water return pressure: 0-0.1MPa

[0090] Circulating cooling water flow rate: ≤380T / h (can be determined by design)

[0091] Compressed air pressure: ≥0.8Mpa normal temperature, dust-free, oil-free

[0092] Power capacity: 380V50Hz 4-wire 125KVA

[0093] Floor area: ≤450㎡ (can be determined by design)

[0094] Equipment height: ≤25 meters (can be determined by design)

[0095] Ambient temperature: 5-35℃

[0096] Ambient humidity: 30%~85%

[0097] Average air pressure: 101Kpa

[0098] Earthquake intensity: ≤7℃

[0099] Ambient wind speed: ≤5m / s.

[0100] The specific method includes the following steps:

[0101] Step 1: The nitric acid wastewater containing aluminum nitrate in the aluminum nitrate tank is pumped to a two-stage column separation system via an aluminum nitrate pump 6, specifically, first pumped into column A, where column A is used as a primary column and column B is used as a secondary column. C column is used as tertiary column, and the nitric acid waste water containing aluminum nitrate enters via the feed port of primary column, flows out from the lower series interface of primary column and enters the feed port of secondary column, and then flows out from the lower port of secondary column and enters the reuse nitric acid tank; When the aluminum content in the effluent of the lower series interface of primary column is more than 80% of the aluminum content in the nitric acid waste water containing aluminum nitrate) containing aluminum content in the nitric acid waste water of aluminum nitrate, it is explained that the primary column is saturated (about 2 times of volume, namely each resin column column contains half of the volume of column feed containing resin volume), close the A series pipeline for connecting the lower series interface of primary column and the upper series interface of secondary column, liquid in the primary column is put back into aluminum nitrate groove 5, after drying, repeatedly clean, dry, then pass into sulfuric acid with mass concentration of 30% to parse out aluminum ions, put into aluminum sulfate solution tank 13 after parsing is completed, when the aluminum sulfate solution outlet detects aluminum ion concentration close to 0, what is basically sulfuric acid in the resin column is, and this part of sulfuric acid is discharged into sulfuric acid tank through sulfuric acid outlet, and then dry, repeatedly clean, dry for use;

[0102] Step 2, the aluminum sulfate solution passed into the aluminum sulfate solution tank 13 in step 1 is pumped to the aluminum sulfate feed tank 18 via the aluminum sulfate raw material pump 14, at this time, the aluminum sulfate solution temperature is ≥20°C (temperature under natural conditions), and the aluminum sulfate solution enters the heat exchanger after being pressurized by the feed pump 19 and is preheated to 64±3°C, and then enters the two-effect three-stage falling film evaporator for evaporation and concentration to obtain a concentrated solution, and the concentrated solution enters the cooling crystallization tank via the triple-effect circulation pump 43, and enters the crystallization transfer tank 21 after preliminary cooling and crystallization. After aluminum sulfate is fully precipitated and crystallized, it enters the filter press for filtration separation, and the solid is put into the high-level tank. The high-level tank in this embodiment specifically includes a high-level tank A / B22 (high-level tank A / B refers to high-level tank A and high-level tank B), a high-level tank C / D23 (high-level tank C / D refers to high-level tank C and high-level tank D) and a high-level tank E21. Aluminum hydroxide is added to each high-level tank, and the temperature is raised to neutralize the residual sulfuric acid. After the neutralization is completed, the scraper discharges the material or the aluminum sulfate solution, and the mother liquor separated by pressure filtration enters the second sulfuric acid tank 15 for standby. The high-level tank is provided with an interlayer, and steam can be passed into the interlayer for heat exchange, thereby achieving internal aluminum sulfate temperature increase. Among them, the high-level tank E21 can also be used as a transfer tank for receiving the neutralized materials in the other high-level tanks.

[0103] Step 3, close the A series pipeline and open the B series pipeline at the same time, use the B column as a new primary column, use the C column as a new secondary column, and use the D column as a new tertiary column, and repeat the operations in the above steps 1 and 2. After the B column reaches saturation, close the B series pipeline and open the C series pipeline at the same time, use the C column as a new primary column, use the D column as a new secondary column, and use the A column as a new tertiary column, and repeat the operations in the above steps 1 and 2. After the C column reaches saturation, close the C series pipeline and open the D series pipeline at the same time, use the D column as a new primary column, use the A column as a new secondary column, and use the B column as a new tertiary column, and repeat the operations in the above steps 1 and 2.

[0104] Step 4: After the D column reaches saturation, close the D series pipeline and open the A series pipeline at the same time, and repeat the operations in the above steps 1, 2 and 3 until all the nitric acid wastewater containing aluminum nitrate is separated and analyzed through the column.

[0105] Furthermore, the specific method for repeatedly cleaning and drying the primary column before sulfuric acid analysis in step 1 is as follows: first, the dilute nitric acid in the dilute nitric acid tank 9 is pumped into the cleaning water inlet by the dilute nitric acid pump 10 and then into the primary column for dilute nitric acid replacement, and after the replacement, all the dilute nitric acid is discharged into the dilute nitric acid tank 9 and then dried; then, the water in the cleaning water tank 3 is pumped into the cleaning water inlet by the cleaning water pump 4 and then into the primary column for water replacement, and after the replacement, all the water is discharged into the dilute nitric acid tank 9 and then dried.

[0106] The specific method of repeatedly cleaning and drying the primary column after sulfuric acid analysis in step 1 is as follows: first, the dilute sulfuric acid in the dilute sulfuric acid tank 11 is pumped into the cleaning water inlet by the dilute sulfuric acid pump 12 and then into the primary column for dilute sulfuric acid replacement, and after the replacement, all the dilute sulfuric acid is discharged into the dilute sulfuric acid tank 11, and then the primary column is dried; then, the water in the cleaning water tank 3 is pumped into the cleaning water inlet by the cleaning water pump 4 and then into the primary column for water replacement, and after the replacement, all the water is discharged into the dilute sulfuric acid tank 11, and then the primary column is dried for standby use.

[0107] Further, in step 3, the specific method of evaporating and concentrating the aluminum sulfate solution by the two-effect three-stage falling film evaporator is as follows: the aluminum sulfate solution first enters the tube side of the first-effect falling film heat exchanger 33, the material in the tube side of the first-effect falling film heat exchanger exchanges heat with the heating steam in the shell of the first-effect falling film heat exchanger to boil and evaporate, and the water vapor generated by evaporation carries part of the droplets into the first-effect falling film evaporation chamber 34, and the water vapor is separated from the droplets in the first-effect falling film evaporation chamber 34 to form the secondary steam, and the secondary steam enters the second-effect falling film heat exchanger 35. The shell layer of the first-effect falling film evaporation chamber 34 contains a part of the droplets separated therein, which is pumped back to the tube side of the first-effect falling film heat exchanger 33 through the first-effect circulation pipeline for further heating and concentration, and the other part is the first-effect concentrated liquid. The first-effect concentrated liquid is pumped to the tube side of the second-effect falling film heat exchanger 35 through the first-effect circulation pump, and exchanges heat with the secondary steam in the shell layer of the second-effect falling film heat exchanger 35 for further evaporation. The water vapor generated by evaporation carries part of the droplets into the second-effect falling film evaporation chamber 36, and the water vapor is separated from the droplets in the second-effect falling film evaporation chamber 36 to form secondary steam; a part of the droplets separated by the second-effect falling film evaporation chamber is pumped back to the tube side of the second-effect falling film heat exchanger 35 through the second-effect circulation pipeline for further heating and concentration, and the other part is the second-effect concentrated liquid The second-effect concentrated liquid is pumped into the tube side of the three-effect falling film heat exchanger 37 by the second-effect circulation pump, and is heat-exchanged with the heating steam in the shell of the three-effect falling film heat exchanger 37 to boil and evaporate. The water vapor generated by evaporation carries part of the droplets into the three-effect falling film evaporation chamber 38. The water vapor is separated from the droplets in the three-effect falling film evaporation chamber 38 to form secondary steam. The secondary steam, together with the secondary steam discharged from the second-effect falling film evaporation chamber 36 and the condensed water generated in the shell of the second-effect falling film heat exchanger 35, enters the first condensed water tank 41. The condensed water generated in the shells of the first-effect falling film heat exchanger and the three-effect falling film heat exchanger flows into the second condensed water tank 44. The condensed water in the second condensed water tank 44 is finally pressed into the preheater 32, and after heat exchange with the aluminum sulfate solution, it enters the V-01 condensed water tank 47.

[0108] Based on the above-mentioned nitric acid wastewater treatment system containing aluminum nitrate and the nitric acid wastewater treatment method containing aluminum nitrate, the cost evaluation of treating 10 tons of nitric acid wastewater containing aluminum nitrate per hour is as follows:

[0109] Comparison conditions

[0110] Working hours: 330 days / year, 24 hours / day,

[0111] Electricity price: 0.82 yuan / KWh Steam price: 195 yuan / ton

[0112] Industrial circulating water: 0.1 yuan / ton Saturated solution boiling point rise: ≤43℃ (saturated solution means that the sulfuric acid content in aluminum sulfate is 55% or above, and a large amount of aluminum sulfate can be precipitated when the temperature is lowered)

[0113] 98% sulfuric acid price: 337.8 yuan / ton; 8% nitric acid price: 188.2 yuan / ton

[0114] Evaporation power: Steam evaporation capacity: 5.688T / h

[0115] 10T / h resin column operating cost table

[0116]

[0117] 10T / h evaporation concentration operation cost table

[0118]

[0119] 10T / h evaporator operation recovery by-product table

[0120]

[0121] Calculating the cost and income per hour shows that each ton can generate 139.36 yuan in revenue, and the use of graphite evaporators avoids equipment corrosion problems, solves the problem of acidic wastewater, and can also generate revenue. This design scheme fully considers the impact of factors such as material composition and dirt on the power consumption of the system in the actual operation of the system, and leaves a certain margin for design parameters and equipment configuration, which can generate economic benefits while treating wastewater.

[0122] The above-mentioned ideal embodiments of the present invention are for inspiration. Through the above-mentioned description, relevant staff can make various changes and modifications without departing from the technical idea of ​​the present invention. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A method for treating nitric acid wastewater containing aluminum nitrate, characterized in that: The method is carried out using a nitric acid wastewater treatment system containing aluminum nitrate, and the nitric acid wastewater treatment system containing aluminum nitrate comprises: A two-stage column separation system, which is used to separate aluminum ions from nitric acid wastewater containing aluminum nitrate, comprises at least three resin columns and a series of pipelines having the same number as the resin columns, wherein the top of the resin column is provided with an upper series interface, a feed port, a compressed air inlet, a cleaning water inlet and a sulfuric acid inlet in parallel, and the bottom of the resin column is provided with a lower series interface, an aluminum sulfate solution outlet, a nitric acid waste liquid outlet and a nitric acid wastewater outlet containing aluminum nitrate in parallel; the resin columns are sequentially connected in series through the series pipelines connected between the lower series interface and the upper series interface to form a loop; An aluminum nitrate tank, the aluminum nitrate tank being provided with a liquid outlet connected to the feed inlet and a liquid return inlet connected to the outlet of the nitric acid wastewater containing aluminum nitrate; It also includes a compressed air pipeline connected to the compressed air inlet, a cleaning water tank connected to the cleaning water inlet, a sulfuric acid tank connected to the sulfuric acid inlet, and an aluminum sulfate solution tank connected to the aluminum sulfate solution outlet; It also includes an aluminum sulfate purification system, which includes an aluminum sulfate feed tank, a preheater, a two-effect three-stage falling film evaporator for multiple evaporation and concentration of aluminum sulfate solution, a cooling crystallization tank, a crystallization transfer tank, a filter press, a high-level tank for receiving solids after filter pressing, and a scraper machine connected in sequence; the aluminum sulfate feed tank is connected to the aluminum sulfate solution tank; The processing method comprises the following steps: Step 1, the nitric acid wastewater containing aluminum nitrate in the aluminum nitrate tank is pumped to a two-stage column separation system, one of the resin columns in the two-stage column separation system is used as a primary column, the resin column connected to the lower serial interface of the primary column with the upper serial interface is used as a secondary column, and the resin column connected to the lower serial interface of the secondary column with the upper serial interface is used as a tertiary column, and the nitric acid wastewater containing aluminum nitrate enters through the feed port of the primary column, flows out from the lower serial interface of the primary column and enters the feed port of the secondary column, and then flows out from the lower port of the secondary column into the reuse nitric acid tank; when the aluminum content in the effluent of the lower serial interface of the primary column is more than 80% of the aluminum content in the nitric acid wastewater containing aluminum nitrate, the series pipeline for connecting the lower serial interface of the primary column and the upper serial interface of the secondary column is closed, and the liquid in the primary column is returned to the aluminum nitrate tank, after drying, it is repeatedly cleaned and dried, and then sulfuric acid with a mass concentration of 20-30% is introduced to parse out aluminum ions, and after the parsing is completed, it is placed in an aluminum sulfate solution tank, dried, and repeatedly cleaned and dried for standby use; Step 2: Pump the aluminum sulfate solution introduced into the aluminum sulfate solution tank in step 1 to the aluminum sulfate feed tank, at which the temperature of the aluminum sulfate solution is ≥20 degrees. The aluminum sulfate solution is pressurized by the feed pump and then enters the heat exchanger to be preheated to 64±3°C, and then enters the two-effect three-stage falling film evaporator for evaporation and concentration to obtain a concentrated solution with a sulfuric acid mass concentration of 55-60%. The concentrated solution enters the cooling crystallization tank through a delivery pump, and enters the crystallization transfer tank after preliminary cooling and crystallization. After aluminum sulfate is fully precipitated, it enters the filter press for filtration separation, and the solid is put into the high-level tank, and aluminum hydroxide is added to the high-level tank. After the residual sulfuric acid is neutralized by heating, the scraper is discharged or water is added to form an aluminum sulfate solution. Step three, simultaneously open the series pipelines for connecting the lower series interface of the secondary column and the upper series interface of the tertiary column, use the secondary column as a new primary column, use the tertiary column as a new secondary column, and use the resin column connected between the upper series interface and the lower series interface of the tertiary column as a new tertiary column, and repeat the above steps one and two until the column separation and analysis of the nitric acid wastewater containing aluminum nitrate is completed.

2. The method for treating nitric acid wastewater containing aluminum nitrate according to claim 1, wherein: There are four resin columns, namely, column A, column B, column C and column D. There are four series pipelines, namely, the A series pipeline for connecting the lower series interface of column A with the upper series connection port of column B, the B series pipeline for connecting the lower series interface of column B with the upper series connection port of column C, the C series pipeline for connecting the lower series interface of column C with the upper series connection port of column D, and the D series pipeline for connecting the lower series interface of column D with the upper series connection port of column A.

3. The method for treating nitric acid wastewater containing aluminum nitrate according to claim 1, characterized in that: It also includes a reuse nitric acid tank connected to the nitric acid waste liquid outlet, and a dilute nitric acid outlet is also connected in parallel at the lower end of the resin column, and the dilute nitric acid outlet is connected to a dilute nitric acid tank for receiving the dilute nitric acid discharged from the resin column for water replacement before aluminum ion desorption; the dilute nitric acid tank is also connected to the washing water inlet of the resin column, and is used to pass dilute nitric acid into the resin column for replacement; And / or, a dilute sulfuric acid outlet is also provided in parallel at the lower end of the resin column, and the dilute sulfuric acid outlet is connected to a dilute sulfuric acid tank for receiving the dilute sulfuric acid discharged from the resin column after water displacement after aluminum ion desorption; the dilute sulfuric acid tank is connected to the cleaning water inlet of the resin column, and is used to pass dilute sulfuric acid into the resin column for displacement.

4. The method for treating nitric acid wastewater containing aluminum nitrate according to claim 1, characterized in that: A sulfuric acid outlet is provided in parallel at the bottom end of the resin column, and the sulfuric acid outlet is connected to a sulfuric acid tank.

5. The method for treating nitric acid wastewater containing aluminum nitrate according to claim 1, characterized in that: The two-effect three-stage falling film evaporator comprises: A single-effect falling film evaporator is used to perform a single-effect falling film evaporation on the aluminum sulfate solution preheated from the preheater to form a single-effect concentrated solution; The two-effect falling film evaporator is used to perform two-effect falling film evaporation on the first-effect concentrated liquid from the first-effect falling film evaporator to form a second-effect concentrated liquid; The three-stage falling film evaporator is used to perform three-effect falling film evaporation on the second-effect concentrated liquid from the two-effect falling film evaporator to form a three-effect concentrated liquid; The single-effect falling film evaporator is provided with a single-effect secondary steam outlet, which is connected to the second-effect falling film evaporator through a pipeline, and is used to send the secondary steam generated by the single-effect falling film evaporator into the second-effect falling film evaporator, and is used as the heat exchange medium of the second-effect falling film evaporator; and also includes a steam pipeline, which is respectively connected to the steam inlet of the single-effect falling film evaporator and the three-stage falling film evaporator, and is used as the heat exchange medium of the single-effect falling film evaporator and the three-stage falling film evaporator.

6. The method for treating nitric acid wastewater containing aluminum nitrate according to claim 5, characterized in that: The aluminum sulfate purification system also includes a first condensed water tank and a second condensed water tank. The first condensed water tank is used to receive the secondary steam generated by the second-effect falling film evaporation chamber and the third-effect falling film evaporation chamber and the condensed water generated in the shell of the second-effect falling film heat exchanger. The second condensed water tank is used to receive the condensed water generated in the shell of the first-effect falling film heat exchanger and the shell of the third-effect falling film heat exchanger.

7. The method for treating nitric acid wastewater containing aluminum nitrate according to claim 6, characterized in that: The second condensed water tank is connected to the preheater and is used to pass condensed water into the preheater as a heat exchange medium for the aluminum sulfate solution.

8. The method for treating nitric acid wastewater containing aluminum nitrate according to claim 1, characterized in that: It also includes a first heat exchanger, wherein the tube side inlet and the tube side outlet of the first heat exchanger are both connected to the high-level tank for condensing the hot steam generated by the reflux high-level tank.

9. The method for treating nitric acid wastewater containing aluminum nitrate according to any one of claims 1 to 8, characterized in that: The specific method of repeatedly cleaning and drying the primary column before sulfuric acid analysis in step 1 is as follows: first, the dilute nitric acid in the dilute nitric acid tank is pumped into the primary column through the cleaning water inlet to replace the dilute nitric acid, and after the replacement, all the dilute nitric acid is discharged into the dilute nitric acid tank, and then dried; then, the water in the cleaning water tank is pumped into the primary column through the cleaning water inlet to replace the water, and after the replacement, all the water is discharged into the dilute nitric acid tank, and then dried; The specific method of repeatedly cleaning and drying the primary column after sulfuric acid analysis in step 1 is as follows: first, the dilute sulfuric acid in the dilute sulfuric acid tank is pumped into the primary column through the cleaning water inlet for dilute sulfuric acid replacement, and after replacement, all the dilute sulfuric acid is discharged into the dilute sulfuric acid tank, and then dried; then, the water in the cleaning water tank is pumped into the primary column through the cleaning water inlet for water replacement, and after replacement, all the water is discharged into the dilute sulfuric acid tank, and then dried for standby use.

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