A method for environmentally friendly resource utilization of sodium sulfate wastewater

Abstract

The invention discloses an environmentally friendly resource utilization method for sodium sulfate wastewater, relates to the field of sodium sulfate wastewater treatment, and solves the problem that the existing environmentally friendly resource utilization method for sodium sulfate wastewater is complicated in equipment operation and is difficult to continuously and efficiently complete the operation process of producing sodium hydroxide from sodium sulfate wastewater. The method comprises a reaction tank, a filtering mechanism and a conveying mechanism. The environmentally friendly resource utilization method for sodium sulfate wastewater comprises the following steps: introducing sodium sulfate wastewater into the reaction tank, then inputting quicklime and a weak acid in equal proportions into the wastewater for reaction to generate a calcium sulfate dihydrate precipitate, filtering and salvaging the precipitate through the filtering mechanism, and outputting it through the conveying mechanism; while the filtering mechanism is running, a set amount of carbon dioxide is linked to be transported into a solution in the reaction tank, the weak acid precipitate is salvaged, a set amount of quicklime is input, sodium hydroxide solution and calcium carbonate precipitate are generated, and after filtering and salvaging the calcium carbonate precipitate, the sodium hydroxide solution and the calcium carbonate precipitate are respectively outputted.

Description

Technical Field

[0001] The invention relates to the technical field of sodium sulfate wastewater treatment, and in particular to an environmentally friendly resource utilization method for sodium sulfate wastewater. Background Art

[0002] Sodium sulfate wastewater is one of the more common high-salt wastewaters in chemical production, hydrometallurgy, battery production, and other fields. For example, the leaching and precipitation processes of nickel and magnesium ores produce large amounts of sodium sulfate wastewater. In metallurgical plants, the neutralization of metals after acid leaching also produces sodium sulfate wastewater. In the field of battery recycling, such as the treatment of waste lead-acid batteries or the wet recycling process of lithium-ion batteries, a certain amount of sodium sulfate wastewater is generated. Given the large amount of sodium sulfate wastewater generated in the above industries and fields, if it is not treated as a resource, it will cause damage to the environment and waste resources.

[0003] Common treatment methods for sodium sulfate high-salinity wastewater include evaporation and crystallization, resin adsorption, membrane separation, and multiple-effect evaporation. However, these methods all have their own drawbacks. Some methods consume a lot of energy and require high equipment investment, while others have low sodium sulfate recovery rates and the risk of secondary pollution. Furthermore, the large number of equipment required makes it difficult to complete the entire sodium sulfate wastewater resource recovery process in a single set of equipment, resulting in low operational efficiency. Therefore, we propose an environmentally friendly resource utilization method for sodium sulfate wastewater. Summary of the Invention

[0004] The object of the present invention is to provide an environmentally friendly resource utilization method for sodium sulfate wastewater, which is convenient for improving the efficiency of preparing sodium hydroxide from sodium sulfate wastewater and reducing the operating process, so as to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for environmentally friendly resource utilization of sodium sulfate wastewater, comprising the following steps:

[0006] S1. Quicklime CaO and weak acid H2A are mixed in water in a ratio of 1:1 to obtain a reaction solution. The reaction equation is: CaO + H2A → CaA + H2O;

[0007] S2. The sodium sulfate Na2SO4 wastewater is passed into the reaction solution of step S1 to react, and the calcium sulfate dihydrate CaSO4·2H2O precipitate is filtered and discharged to obtain product 1. The reaction temperature is 30°C, the reaction time is 2 hours, and the reaction equation is: Na2SO4+CaA+2H2O→CaSO4·2H2O↓+Na2A;

[0008] S3, carbon dioxide CO2 is introduced into the liquid of step S2 to produce a high concentration of sodium bicarbonate NaHCO3 solution and a weak acid H2A. The weak acid H2A can be reused. The reaction temperature is 30°C and the reaction time is 4 hours. The reaction equation is: Na2A + 2CO2 + 2H2O → H2A + 2NaHCO3;

[0009] S4. Continue to add sufficient quicklime CaO to the liquid in step S3. The quicklime CaO and the weak acid H2A react in step S1 again. Then, the excess quicklime CaO reacts with water to generate calcium hydroxide Ca(OH)2. Then, the calcium hydroxide Ca(OH)2 reacts with a high concentration of sodium bicarbonate NaHCO3 solution to generate the desired sodium hydroxide NaOH product 2 and calcium carbonate CaCO3 precipitation product 3. The reaction equation is: NaHCO3 + Ca(OH)2 = NaOH + CaCO3↓ + H2O.

[0010] Preferably, the method comprises a reaction tank, a filtering mechanism and a conveying mechanism, wherein in step S1 and step S2, the sodium sulfate wastewater is first introduced into the reaction tank, and then quicklime and weak acid in equal proportions are input into the wastewater for reaction to generate a calcium sulfate dihydrate precipitate, the calcium sulfate dihydrate precipitate is filtered and salvaged by the filtering mechanism, and outputted by the conveying mechanism, and while the filtering mechanism is running, the conveying mechanism is linked to deliver a set amount of carbon dioxide to the solution in the reaction tank, completing step S3 to generate a high-concentration sodium bicarbonate solution and a weak acid precipitate, the weak acid precipitate is again salvaged by the filtering mechanism, and then a set amount of quicklime is input into the reaction tank by the conveying mechanism, completing step S4 to generate a sodium hydroxide solution and a calcium carbonate precipitate, after the calcium carbonate precipitate is filtered and salvaged by the filtering mechanism, the sodium hydroxide solution and the calcium carbonate precipitate are respectively outputted by the conveying mechanism, so that only the weak acid precipitate is retained in the reaction tank for reuse, and the device is reset to perform the next group of sodium sulfate wastewater treatment operations, thereby improving the efficiency of preparing sodium hydroxide from sodium sulfate wastewater and reducing the operation process.

[0011] Preferably, the filtering mechanism includes a first filter screen, a second filter screen and a third filter screen that are slidably fitted with the inner wall of the reaction tank, the bottom of the reaction tank is rotatably connected to a rotating disk, and three groups of electric telescopic rods are provided on the upper side of the reaction tank. The telescopic ends of the three groups of electric telescopic rods are respectively fixedly connected to the first lifting rod, the second lifting rod and the third lifting rod, the first lifting rod is fixedly connected to the top surface of the first filter screen, the second lifting rod is fixedly connected to the top surface of the second filter screen, and the third lifting rod is fixedly connected to the top surface of the third filter screen. The second lifting rod passes through the first filter screen and is slidably connected to the first filter screen in a vertical direction. The third lifting rod passes through the first filter screen and the second filter screen, and is slidably connected to the first filter screen and the second filter screen in a vertical direction, so as to facilitate the separation and transportation of the precipitate produced by the reaction.

[0012] Preferably, the conveying mechanism includes a top plate rotatably connected to the top of the reaction tank, the upper side of the top plate is fixedly connected to a mounting plate, multiple groups of the electric telescopic rods are fixedly mounted on the mounting plate, the bottom surface of the top plate is fixedly connected to two groups of telescopic tubes, a lifting plate is movably connected in the reaction tank, the first lifting rod, the second lifting rod and the third lifting rod all pass through the top plate and the lifting plate, and are slidably connected to the top plate and the lifting plate, the bottom of the two groups of telescopic tubes are fixedly connected to the top surface of the lifting plate, the area between the two groups of telescopic tubes and the top plate and the lifting plate is used to store a set amount of carbon dioxide, the bottom surface of the top plate is fixedly connected to a return spring fixedly connected to the top surface of the lifting plate, the top plate is provided with a control component for controlling the delivery of carbon dioxide, and the reaction tank is provided with a conveying component for controlling the delivery of raw materials and products, which is convenient for conveying control of the raw materials and products of the reaction.

[0013] Preferably, the control component includes an annular tube fixedly mounted on the top of the reaction tank, the bottom surface of the annular tube slides in contact with the top surface of the top plate, the annular tube is connected to a gas pipe for inputting carbon dioxide gas, a plurality of connecting holes connected to the annular tube are provided on the top plate, a one-way air inlet valve for controlling the one-way input of gas to the lower side of the top plate is provided in the connecting hole, an output component for transporting carbon dioxide to the inside of the reaction tank is provided on the top plate, so as to facilitate the control of carbon dioxide delivery.

[0014] Preferably, the output member includes a drive shaft fixedly mounted on the rotating disk, the drive shaft passes through the first filter screen, the second filter screen, the third filter screen and the lifting plate, the side of the drive shaft is evenly and fixedly connected with multiple groups of guide rods that are slidably connected to the first filter screen, the second filter screen, the third filter screen and the lifting plate in the vertical direction, the top end of the drive shaft is fixedly connected to the top plate, and a gas delivery member for unidirectional delivery of gas is provided in the drive shaft to facilitate the delivery of carbon dioxide to the interior of the reaction tank.

[0015] Preferably, the gas delivery component includes multiple groups of one-way exhaust valves installed on the top plate, multiple groups of first pipes are provided on the top plate, a second pipe connected to the first pipe is provided in the drive shaft, a side hole connected to the second pipe is provided on the bottom end side of the drive shaft, the opening position of the side hole conflicts with the inner wall of the first filter screen, the one-way exhaust valve is fixedly installed in the first pipe, and is used to control the one-way input of gas from the first pipe to the second pipe, so as to facilitate the one-way delivery of gas.

[0016] Preferably, the conveying member includes multiple groups of output rods fixedly installed on the bottom surface of the lifting plate, the side of the reaction tank is connected to an inlet pipe for inputting sodium sulfate wastewater, the bottom end of the side of the reaction tank is connected to an outlet pipe for outputting sodium hydroxide liquid, one end opening of the outlet pipe conflicts with the outer wall of the third filter screen, the side of the reaction tank is provided with an input trough for inputting quicklime and weak acid solids, the side of the reaction tank is provided with an output trough for outputting calcium carbonate solid precipitate, the side of the reaction tank is provided with an output pipe for outputting calcium sulfate dihydrate precipitate, the height of the opening at one end of the output pipe is flush with the height of the output rod, which is convenient for controlling the transportation of raw materials and products.

[0017] Preferably, the bottom of the reaction tank is fixedly connected to a base, the base is fixedly connected to a drive motor, the output end of the drive motor is coaxially fixedly connected to the bottom end of the drive shaft, and multiple groups of stirring rods are fixedly connected to the rotating disk. The stirring rods pass through the first filter screen, the second filter screen, the third filter screen and the lifting plate, and are slidably connected to the first filter screen, the second filter screen, the third filter screen and the lifting plate in a vertical direction, so as to facilitate stirring operation during the reaction and improve reaction efficiency.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention provides an environmentally friendly resource utilization method for sodium sulfate wastewater, which solves the problem that the equipment operation is cumbersome when the existing environmentally friendly resource utilization method for sodium sulfate wastewater is used, and it is difficult to continuously and efficiently complete the operation process of producing sodium hydroxide from sodium sulfate wastewater. The method is convenient for first introducing sodium sulfate wastewater into a reaction tank, then inputting quicklime and weak acid in equal proportions into the wastewater for reaction to generate calcium sulfate dihydrate precipitate, filtering and salvaging the calcium sulfate dihydrate precipitate through a filtering mechanism, and outputting it through a conveying mechanism. While the filtering mechanism is running, the conveying mechanism is linked to deliver a set amount of carbon dioxide into the solution in the reaction tank, thereby generating a high-concentration sodium bicarbonate solution and a weak acid precipitate, and the weak acid precipitate is salvaged again through the filtering mechanism, and then the sodium bicarbonate solution is output through the conveying mechanism. The conveying mechanism inputs a set amount of quicklime into the reaction tank to generate a sodium hydroxide solution and a calcium carbonate precipitate. After the calcium carbonate precipitate is filtered and salvaged by the filtering mechanism, the sodium hydroxide solution and the calcium carbonate precipitate are respectively outputted by the conveying mechanism, so that only the weak acid precipitate remains in the reaction tank for reuse. After the device is reset, the next group of sodium sulfate wastewater treatment operations are performed again. The production cost of this method is low. Only quicklime, carbon dioxide gas and a weak acid that can be recycled are used to produce sodium hydroxide, calcium carbonate and calcium sulfate dihydrate with high utilization value. The sodium ions in the wastewater are converted into industrial raw materials such as sodium hydroxide, which are used to manufacture products such as soap, glass, and paper, thereby realizing the resource utilization of wastewater and generating economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0021] Figure 2 It is a schematic diagram of the local structure of the filtering mechanism of the present invention;

[0022] Figure 3 It is a schematic diagram of the partial structure of the conveying mechanism of the present invention;

[0023] Figure 4 for Figure 3 Enlarged view of area A in the middle;

[0024] Figure 5 This is an exploded view of the local structure of the filtering mechanism of the present invention;

[0025] Figure 6 for Figure 5 Enlarged view of area B in the middle;

[0026] Figure 7 This is a partial structural cross-sectional view of the filter mechanism of the present invention;

[0027] Figure 8 for Figure 7 Enlarged view of area C in the middle;

[0028] Figure 9It is a partial structural cross-sectional view of the conveying mechanism of the present invention;

[0029] Figure 10 for Figure 9 Enlarged view of area D in the middle.

[0030] In the figure: 1-reaction tank; 2-filter mechanism; 3-conveyance mechanism; 4-first filter screen; 5-second filter screen; 6-third filter screen; 7-rotating disk; 8-electric telescopic rod; 9-first lifting rod; 10-second lifting rod; 11-third lifting rod; 12-top plate; 13-mounting plate; 14-telescopic tube; 15-lifting plate; 16-reset spring; 17-control member; 19-annular tube; 20-air pipe; 21-connecting hole; 22-one-way air inlet valve; 23-output member; 24-drive shaft; 25-guide rod; 26-air delivery member; 27-one-way exhaust valve; 28-first pipeline; 29-second pipeline; 30-side hole; 31-output rod; 32-water inlet pipe; 33-water outlet pipe; 35-input tank; 36-output tank; 37-output pipe; 38-base; 39-drive motor; 40-stirring rod. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] Example 1

[0033] See also Figures 1-10 The method for environmentally friendly resource utilization of sodium sulfate wastewater shown in the figure includes the following steps:

[0034] S1. Quicklime CaO and weak acid H2A are mixed in water in a ratio of 1:1 to obtain a reaction solution. The reaction equation is: CaO + H2A → CaA + H2O;

[0035] S2. The sodium sulfate Na2SO4 wastewater is passed into the reaction solution of step S1 to react, and the calcium sulfate dihydrate CaSO4·2H2O precipitate is filtered and discharged to obtain product 1. The reaction temperature is 30°C, the reaction time is 2 hours, and the reaction equation is: Na2SO4+CaA+2H2O→CaSO4·2H2O↓+Na2A;

[0036] S3, carbon dioxide CO2 is introduced into the liquid of step S2 to produce a high concentration of sodium bicarbonate NaHCO3 solution and a weak acid H2A. The weak acid H2A can be reused. The reaction temperature is 30°C and the reaction time is 4 hours. The reaction equation is: Na2A + 2CO2 + 2H2O → H2A + 2NaHCO3;

[0037] S4. Continue to add sufficient quicklime CaO to the liquid in step S3. The quicklime CaO and the weak acid H2A react in step S1 again. Then, the excess quicklime CaO reacts with water to generate calcium hydroxide Ca(OH)2. Then, the calcium hydroxide Ca(OH)2 reacts with a high concentration of sodium bicarbonate NaHCO3 solution to generate the desired sodium hydroxide NaOH product 2 and calcium carbonate CaCO3 precipitation product 3. The reaction equation is: NaHCO3 + Ca(OH)2 = NaOH + CaCO3↓ + H2O.

[0038] See also Figures 1-10 The figure shows an environmentally friendly resource utilization method for sodium sulfate wastewater, comprising a reaction tank 1, a filtering mechanism 2, and a conveying mechanism 3. In steps S1 and S2, the sodium sulfate wastewater is first introduced into the reaction tank 1, and then quicklime and a weak acid in equal proportions are introduced into the wastewater for reaction to generate a calcium sulfate dihydrate precipitate. The calcium sulfate dihydrate precipitate is filtered and salvaged by the filtering mechanism 2 and discharged through the conveying mechanism 3. While the filtering mechanism 2 is operating, the conveying mechanism 3 is linked to deliver a set amount of carbon dioxide to the solution in the reaction tank 1, completing step S3 to generate a high-concentration sodium bicarbonate solution and a weak acid precipitate. The weak acid precipitate is again salvaged by the filtering mechanism 2, and a set amount of quicklime is then introduced into the reaction tank 1 through the conveying mechanism 3 to complete step S4 to generate a sodium hydroxide solution and a calcium carbonate precipitate. After the calcium carbonate precipitate is filtered and salvaged by the filtering mechanism 2, the sodium hydroxide solution and the calcium carbonate precipitate are separately discharged through the conveying mechanism 3, so that only the weak acid precipitate remains in the reaction tank 1 for reuse. After the device is reset, the next group of sodium sulfate wastewater treatment operations are performed again.

[0039] In this embodiment, bisphenol AF can be used as the weak acid. Sodium sulfate wastewater is first introduced into the reaction tank 1, and then quicklime and bisphenol AF in equal proportions are input into the wastewater for reaction to produce a dihydrated calcium sulfate precipitate. The dihydrated calcium sulfate precipitate is filtered and salvaged by the filtering mechanism 2 and output through the conveying mechanism 3 to complete steps S1 and S2. While the filtering mechanism 2 is running, the conveying mechanism 3 is linked to deliver a set amount of carbon dioxide to the solution in the reaction tank 1 to complete step S3, thereby producing a high-concentration sodium bicarbonate solution and a bisphenol AF precipitate. The bisphenol AF precipitate is again salvaged by the filtering mechanism 2, and then a set amount of quicklime is input into the reaction tank 1 through the conveying mechanism 3 to complete step S4, thereby producing a sodium hydroxide solution and a calcium carbonate precipitate. After the calcium carbonate precipitate is filtered and salvaged by the filtering mechanism 2, the sodium hydroxide solution and the calcium carbonate precipitate are respectively output through the conveying mechanism 3, so that only the weak acid precipitate is retained in the reaction tank 1 for reuse. After the device is reset, the next group of sodium sulfate wastewater treatment operations are performed again.

[0040] Example 2

[0041] See also Figures 1-10 Example 2 is described. This example further illustrates Example 1. The filtering mechanism 2 shown in the figure includes a first filter screen 4, a second filter screen 5 and a third filter screen 6 that are slidably fitted with the inner wall of the reaction tank 1. The bottom of the reaction tank 1 is rotatably connected to a rotating disk 7. Three groups of electric telescopic rods 8 are provided on the upper side of the reaction tank 1. The telescopic ends of the three groups of electric telescopic rods 8 are fixedly connected to a first lifting rod 9, a second lifting rod 10 and a third lifting rod 11 respectively. The first lifting rod 9 is fixedly connected to the top surface of the first filter screen 4, the second lifting rod 10 is fixedly connected to the top surface of the second filter screen 5, and the third lifting rod 11 is fixedly connected to the top surface of the third filter screen 6. The second lifting rod 10 passes through the first filter screen 4 and is slidably connected to the first filter screen 4 in a vertical direction. The third lifting rod 11 passes through the first filter screen 4 and the second filter screen 5 and is slidably connected to the first filter screen 4 and the second filter screen 5 in a vertical direction.

[0042] The conveying mechanism 3 includes a top plate 12 rotatably connected to the top of the reaction tank 1, a mounting plate 13 is fixedly connected to the upper side of the top plate 12, and multiple groups of electric telescopic rods 8 are fixedly mounted on the mounting plate 13. The bottom surface of the top plate 12 is fixedly connected to two groups of telescopic tubes 14. A lifting plate 15 is movably connected inside the reaction tank 1. The first lifting rod 9, the second lifting rod 10 and the third lifting rod 11 all pass through the top plate 12 and the lifting plate 15, and are slidably connected to the top plate 12 and the lifting plate 15. The bottoms of the two groups of telescopic tubes 14 are fixedly connected to the top surface of the lifting plate 15. The area between the two groups of telescopic tubes 14 and the top plate 12 and the lifting plate 15 is used to store a set amount of carbon dioxide. The bottom surface of the top plate 12 is fixedly connected to a return spring 16 fixedly connected to the top surface of the lifting plate 15. A control part 17 for controlling the delivery of carbon dioxide is provided on the top plate 12, and a conveying part for controlling the delivery of raw materials and products is provided on the reaction tank 1.

[0043] The control component 17 includes an annular tube 19 fixedly mounted on the top of the reaction tank 1. The bottom surface of the annular tube 19 slides in contact with the top surface of the top plate 12. The annular tube 19 is connected to a gas pipe 20 for inputting carbon dioxide gas. The top plate 12 is provided with multiple groups of connecting holes 21 connected to the annular tube 19. The connecting holes 21 are provided with a one-way air inlet valve 22 for controlling the one-way input of gas to the lower side of the top plate 12. The top plate 12 is provided with an output component 23 for transporting carbon dioxide to the inside of the reaction tank 1.

[0044] The output member 23 includes a drive shaft 24 fixedly mounted on the rotating disk 7, the drive shaft 24 passes through the first filter screen 4, the second filter screen 5, the third filter screen 6 and the lifting plate 15, and the side of the drive shaft 24 is evenly fixedly connected with multiple groups of guide rods 25 that are slidably connected to the first filter screen 4, the second filter screen 5, the third filter screen 6 and the lifting plate 15 in the vertical direction. The top of the drive shaft 24 is fixedly connected to the top plate 12, and the bottom of the reaction tank 1 is fixedly connected to the base 38, and the base 38 is fixedly connected to the drive motor 39. The model of the drive motor 39 is preferably Y80M1-2. The output end of the drive motor 39 is coaxially fixedly connected to the bottom end of the drive shaft 24, and a gas transmission member 26 for unidirectional transportation of gas is provided in the drive shaft 24.

[0045] The gas delivery component 26 includes multiple sets of one-way exhaust valves 27 installed on the top plate 12. Multiple sets of first pipes 28 are opened on the top plate 12. A second pipe 29 connected to the first pipe 28 is opened in the drive shaft 24. A side hole 30 connected to the second pipe 29 is opened on the bottom end side of the drive shaft 24. The opening position of the side hole 30 conflicts with the inner wall of the first filter 4. The one-way exhaust valve 27 is fixedly installed in the first pipe 28 and is used to control the one-way input of gas from the first pipe 28 to the second pipe 29.

[0046] The conveying member includes multiple groups of output rods 31 fixedly mounted on the bottom surface of the lifting plate 15. The side of the reaction tank 1 is connected to an inlet pipe 32 for inputting sodium sulfate wastewater, and the bottom end of the side of the reaction tank 1 is connected to an outlet pipe 33 for outputting sodium hydroxide liquid. One end opening of the outlet pipe 33 conflicts with the outer wall of the third filter 6. The side of the reaction tank 1 is provided with an input groove 35 for inputting quicklime and weak acid solids, and the side of the reaction tank 1 is provided with an output groove 36 for outputting calcium carbonate solid precipitate. The side of the reaction tank 1 is provided with an output pipe 37 for outputting calcium sulfate dihydrate precipitate, and the height of the opening at one end of the output pipe 37 is flush with the height of the output rod 31.

[0047] In this embodiment, the electric telescopic rod 8 is started to push out the first lifting rod 9, the second lifting rod 10 and the third lifting rod 11, so that the first filter 4, the second filter 5 and the third filter 6 conflict with each other and are at the bottom end position of the reaction tank 1. At this time, the third filter 6 blocks the water outlet pipe 33, and the inner wall of the first filter 4 blocks the side hole 30. A set amount of sodium sulfate wastewater is input through the water inlet pipe 32, and then a proportional set amount of quicklime and bisphenol AF is input through the input groove 35 to control the reaction temperature and reaction time of the reaction tank 1. The drive motor 39 is started to drive the drive shaft 24 and the rotating disk 7 to rotate, so that the raw materials in the reaction tank 1 are mixed and reacted to produce calcium sulfate dihydrate precipitate. At this time, a group of electric telescopic rods 8 are started to drive the first lifting rod 9 to move upward, which can drive the first filter 4 to move upward, and the calcium sulfate dihydrate precipitate is filtered and salvaged. The liquid passes through the first filter 4 and flows into the upper side of the second filter 5.

[0048] When the first filter screen 4 moves up and contacts the bottom surface of the output rod 31, it pushes the lifting plate 15 to move up. At the same time, as the first filter screen 4 and the lifting plate 15 rotate and rise, the output rod 31 is tilted, and the sediment on the upper side of the first filter screen 4 is thrown to the surroundings and discharged into the output pipe 37 when it reaches the position of the output pipe 37 for collection. When the lifting plate 15 moves up, the space between the lifting plate 15 and the top plate 12 is compressed, so that the carbon dioxide in the telescopic tube 14 is squeezed through the first pipe 28, the one-way exhaust valve 27 and the second pipe 29 to be output into the side hole 30, and then discharged into the solution at the bottom through the side hole 30 to carry out the reaction in step S3, thereby producing a high-concentration sodium bicarbonate solution and bisphenol AF precipitate.

[0049] Another set of electric telescopic rods 8 is started to drive the second lifting rod 10 to move upward, so that the second filter screen 5 can be moved upward to filter and salvage the bisphenol AF precipitate. When the second filter screen 5 moves to the upper side of the input slot 35, the input slot 35 is opened, and a sufficient amount of quicklime is added to the reaction tank 1 to carry out the reaction of step S4, thereby producing a sodium hydroxide solution and a calcium carbonate precipitate in the reaction tank 1. Thereafter, the electric telescopic rod 8 is started to drive the third lifting rod 11 and the third filter screen 6 to move upward, so that the calcium carbonate precipitate can be filtered and salvaged through the third filter screen 6 and discharged after reaching the position of the output slot 36. When the third filter screen 6 moves upward, the blockage of the water outlet pipe 33 is released, and the sodium hydroxide solution in the reaction tank 1 can be discharged through the water outlet pipe 33. Subsequent drying and crystallization operations are carried out to obtain a sodium hydroxide solid product.

[0050] After the reaction is completed, the electric telescopic rod 8 is driven to move the third filter 6, the second filter 5 and the first filter 4 downward and reset in sequence, and the reset spring 16 rebounds, causing the lifting plate 15 to move downward and the contraction tube to expand, and the carbon dioxide in the intake pipe is drawn into the annular tube 19, and then through the connecting hole 21 and the one-way air intake valve 22 into the telescopic tube 14 on the lower side of the top plate 12, completing the storage function of quantitative carbon dioxide. At this time, there is a large amount of bisphenol AF precipitation between the second filter 5 and the first filter 4. At this time, it is necessary to add clean water and a set amount of quicklime to react with bisphenol AF, and then lower the first filter 4 again so that the first filter 4 and the second filter 5 are fitted together, and then the filtered sodium sulfate wastewater is introduced, and the reaction of step S2 can be carried out again. This reciprocating process can continuously utilize the initial bisphenol AF, the newly added carbon dioxide and quicklime to complete the environmentally friendly resource utilization of sodium sulfate wastewater.

[0051] It is worth noting that the one-way exhaust valve 27 can be set in the side hole 30 to prevent the liquid from entering the enemy pipeline through the side hole 30. This method has a low production cost and only uses quicklime, carbon dioxide gas and weak acid that can be recycled to produce sodium hydroxide, calcium carbonate and calcium sulfate dihydrate with high utilization value. The sodium ions in the wastewater are converted into industrial raw materials such as sodium hydroxide, which are used to manufacture soap, glass, paper and other products, thereby realizing the resource utilization of wastewater and generating economic benefits.

[0052] Example 3

[0053] See also Figures 1-10 Example 3 is described. This example further illustrates Example 1. A plurality of stirring rods 40 are fixedly connected to the rotating disk 7 shown in the figure. The stirring rods 40 pass through the first filter screen 4, the second filter screen 5, the third filter screen 6 and the lifting plate 15, and are slidably connected to the first filter screen 4, the second filter screen 5, the third filter screen 6 and the lifting plate 15 in the vertical direction.

[0054] In this embodiment, when the driving motor 39 drives the driving shaft 24 and the rotating disk 7 to rotate, the rotating disk 7 can drive the stirring rod 40 to rotate to improve the reaction efficiency of the raw materials in the reaction tank 1, and at the same time will not affect the lifting and lowering movement of the first filter screen 4, the second filter screen 5 and the third filter screen 6, and the operation is efficient and convenient.

[0055] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0056] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for environmentally friendly resource utilization of sodium sulfate wastewater, characterized in that: The following steps are involved: S1, quicklime and weak acid are mixed in water in a ratio of 1:1 to obtain a reaction solution; S2. Passing the sodium sulfate wastewater into the reaction solution of step S1 to react to obtain calcium sulfate dihydrate precipitate, which is filtered and discharged. The reaction temperature is 30° C. and the reaction time is 2 h; S3, carbon dioxide is introduced into the liquid of step S2 to produce a sodium bicarbonate solution and a weak acid precipitate, the weak acid is filtered and reused, the reaction temperature is 30°C, and the reaction time is 4 hours; S4, continue to add enough quicklime to the liquid of step S3, quicklime will react with water to form calcium hydroxide, and then calcium hydroxide will react with sodium bicarbonate solution to form required sodium hydroxide and calcium carbonate precipitation; Also includes: The reaction tank, the filtering mechanism and the conveying mechanism are as follows: in the steps S1 and S2, the sodium sulfate wastewater is first introduced into the reaction tank, and then the quicklime and weak acid in the same proportion are input into the wastewater for reaction to generate a dihydrated calcium sulfate precipitate, the dihydrated calcium sulfate precipitate is filtered and salvaged by the filtering mechanism, and outputted by the conveying mechanism; while the filtering mechanism is running, the conveying mechanism is linked to deliver a set amount of carbon dioxide to the solution in the reaction tank, completing step S3, generating a sodium bicarbonate solution and a weak acid precipitate, and the weak acid precipitate is salvaged again by the filtering mechanism, and then a set amount of quicklime is input into the reaction tank by the conveying mechanism, completing step S4, generating a sodium hydroxide solution and a calcium carbonate precipitate, and after the calcium carbonate precipitate is filtered and salvaged by the filtering mechanism, the sodium hydroxide solution and the calcium carbonate precipitate are separated by the conveying mechanism. The filter mechanism comprises a first filter screen, a second filter screen and a third filter screen which are slidably fitted with the inner wall of the reaction tank. The bottom of the reaction tank is rotatably connected to a rotating disk. Three groups of electric telescopic rods are provided on the upper side of the reaction tank. The telescopic ends of the three groups of electric telescopic rods are respectively fixedly connected to the first lifting rod, the second lifting rod and the third lifting rod. The first lifting rod is fixedly connected to the top surface of the first filter screen, the second lifting rod is fixedly connected to the top surface of the second filter screen, and the third lifting rod is fixedly connected to the top surface of the third filter screen. The second lifting rod passes through the first filter screen and is slidably connected to the first filter screen in a vertical direction. The third lifting rod passes through the first filter screen and the second filter screen and is slidably connected to the first filter screen and the second filter screen in a vertical direction.

2. A method for environmentally friendly resource utilization of sodium sulfate wastewater according to claim 1, characterized in that: The conveying mechanism includes a top plate rotatably connected to the top of the reaction tank, a mounting plate fixedly connected to the upper side of the top plate, multiple groups of electric telescopic rods are fixedly installed on the mounting plate, two groups of telescopic tubes are fixedly connected to the bottom surface of the top plate, a lifting plate is movably connected in the reaction tank, the first lifting rod, the second lifting rod and the third lifting rod all pass through the top plate and the lifting plate, and are slidably connected to the top plate and the lifting plate, the bottoms of the two groups of telescopic tubes are fixedly connected to the top surface of the lifting plate, the area between the two groups of telescopic tubes and the top plate and the lifting plate is used to store a set amount of carbon dioxide, the bottom surface of the top plate is fixedly connected to a reset spring fixedly connected to the top surface of the lifting plate, a control component for controlling the delivery of carbon dioxide is provided on the top plate, and a conveying component for controlling the delivery of raw materials and products is provided on the reaction tank.

3. A method for environmentally friendly resource utilization of sodium sulfate wastewater according to claim 2, characterized in that: The control component includes an annular tube fixedly installed on the top of the reaction tank. The bottom surface of the annular tube slides in contact with the top surface of the top plate. The annular tube is connected to a gas pipe for inputting carbon dioxide gas. A plurality of connecting holes connected to the annular tube are provided on the top plate. A one-way air inlet valve for controlling the one-way input of gas to the lower side of the top plate is provided in the connecting holes. An output component for transporting carbon dioxide to the inside of the reaction tank is provided on the top plate.

4. A method for environmentally friendly resource utilization of sodium sulfate wastewater according to claim 3, characterized in that: The output member includes a drive shaft fixedly mounted on the rotating disk, the drive shaft passes through the first filter screen, the second filter screen, the third filter screen and the lifting plate, the side of the drive shaft is evenly and fixedly connected with multiple groups of guide rods that are slidably connected to the first filter screen, the second filter screen, the third filter screen and the lifting plate in the vertical direction, the top end of the drive shaft is fixedly connected to the top plate, and a gas transmission member for unidirectionally transporting gas is provided in the drive shaft.

5. A method for environmentally friendly resource utilization of sodium sulfate wastewater according to claim 4, characterized in that: The gas transmission parts include multiple groups of one-way exhaust valves installed on the top plate, multiple groups of first pipes are opened on the top plate, a second pipe connected to the first pipe is opened in the drive shaft, and a side hole connected to the second pipe is opened on the bottom end side of the drive shaft. The opening position of the side hole conflicts with the inner wall of the first filter screen. The one-way exhaust valve is fixedly installed in the first pipe and is used to control the one-way input of gas from the first pipe to the second pipe.

6. A method for environmentally friendly resource utilization of sodium sulfate wastewater according to claim 2, characterized in that: The conveying parts include multiple groups of output rods fixedly installed on the bottom surface of the lifting plate. The side of the reaction tank is connected to an inlet pipe for inputting sodium sulfate wastewater, and the bottom end of the side of the reaction tank is connected to an outlet pipe for outputting sodium hydroxide liquid. One end opening of the outlet pipe conflicts with the outer wall of the third filter screen. The side of the reaction tank is provided with an input trough for inputting quicklime and weak acid solids, the side of the reaction tank is provided with an output trough for outputting calcium carbonate solid precipitate, and the side of the reaction tank is provided with an output pipe for outputting calcium sulfate dihydrate precipitate. The height of the opening at one end of the output pipe is flush with the height of the output rod.

7. A method for environmentally friendly resource utilization of sodium sulfate wastewater according to claim 4, characterized in that: The bottom of the reaction tank is fixedly connected to a base, and a driving motor is fixedly connected to the base. The output end of the driving motor is coaxially fixedly connected to the bottom end of the driving shaft. Multiple groups of stirring rods are fixedly connected to the rotating disk. The stirring rods pass through the first filter screen, the second filter screen, the third filter screen and the lifting plate, and are slidably connected to the first filter screen, the second filter screen, the third filter screen and the lifting plate in the vertical direction.

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