A sodium phosphate dibasic method for recycling phosphorus resources from a ferrous phosphate mother liquor

Abstract

The utility model discloses a kind of sodium hydrogen phosphate method iron phosphate mother liquor phosphorus resource recycling system, it is related to iron phosphate production technical field, including oxidation reaction kettle and neutralization adjusting kettle, oxidation reaction kettle is equipped with ferrous solution inlet pipe, mother liquor inlet pipe, hydrogen peroxide inlet pipe and first discharge pipe, first discharge pipe is equipped with first filter, first filter is equipped with first filtrate pipe, first filtrate pipe is connected with neutralization adjusting kettle, neutralization adjusting kettle is equipped with lye inlet pipe, PAM inlet pipe and second discharge pipe, second discharge pipe is connected with reflux sedimentation tank, reflux sedimentation tank is connected with second filter, second filter is equipped with second filtrate pipe.The utility model can reach more than 95% in phosphorus recovery rate in mother liquor, total phosphorus utilization rate of iron phosphate synthesis can reach 99.9%.

Description

Technical Field

[0001] This utility model belongs to the field of iron phosphate production technology, specifically relating to a system for recovering and reusing phosphorus resources from iron phosphate mother liquor produced by the disodium hydrogen phosphate method. Background Technology

[0002] Iron phosphate is the core precursor for preparing lithium iron phosphate, a cathode battery material. The synthesized lithium iron phosphate has safety and long cycle life, and is widely used in electric vehicles, energy storage systems, etc.

[0003] There are various production processes for iron phosphate, including six main methods: sodium method, ammonium method, iron powder method, fertilizer phosphoric acid method, iron oxide red method, and dicalcium phosphate method.

[0004] Our company synthesizes ferric phosphate using disodium hydrogen phosphate, a byproduct of our glyphosate production, as the phosphorus source. It is added dropwise with ferrous sulfate and hydrogen peroxide to initially produce crude ferric phosphate. After pressure filtration, the crude ferric phosphate yields a filter cake and a crude mother liquor. The filter cake is then further aged with phosphoric acid to adjust the pH of the reaction system to approximately 2, and the resulting product is synthesized as ferric phosphate. The aging mother liquor is reused.

[0005] The crude mother liquor contains: phosphorus 220–580 mg / L, iron ion 50–130 mg / L, sodium ion 22300–51400 mg / L, magnesium ion 130–150 mg / L, sulfate ion 46540–107230 mg / L, manganese ion 80–110 mg / L, and calcium ion 13–45 mg / L. The mother liquor must be treated before being discharged. The phosphorus content in the crude mother liquor is approximately 0.5% to 1% of the total phosphorus content. If it is disposed of as waste, the amount to be treated is large, the wastewater treatment cost is high, and it does not conform to the concept of green and pollution-free industrial production.

[0006] Based on the above reasons and adhering to the principle of reducing waste and pollution at the source, our company has developed a new pretreatment system that recovers a large amount of phosphorus source from the mother liquor. The recovered phosphorus source is then reused in the synthesis of iron phosphate, thereby greatly increasing the utilization rate of phosphorus and reducing the emission of phosphorus resources. Utility Model Content

[0007] The purpose of this invention is to solve the problems of existing technologies and provide a system for recovering and reusing phosphorus resources from the mother liquor of ferric phosphate produced by the disodium hydrogen phosphate method. The mother liquor of ferric phosphate produced by the disodium hydrogen phosphate method flows into an oxidation reactor through a mother liquor inlet pipe. The pH value in the oxidation reactor is adjusted to 1-1.5. Ferrous sulfate solution and hydrogen peroxide are then added through ferrous solution inlet pipe and hydrogen peroxide inlet pipe, respectively. Crude ferric phosphate solution is synthesized in the oxidation reactor. The crude ferric phosphate solution is discharged into a first filter through a first discharge pipe. The filtered crude ferric phosphate filter cake is used in an aging step (aging reactor). The first filtrate after filtration is discharged into a neutralization and adjustment reactor through a first filtrate pipe. Sodium hydroxide solution is added to the neutralization and adjustment reactor through an alkali inlet pipe to control the pH in the neutralization and adjustment reactor to 7-8. PAM solution is then added through a PAM inlet pipe to precipitate and remove other metal impurities. The supernatant is used in the sodium sulfate recovery process to recover sodium sulfate. The impurity metal ion content is extremely low. This invention can achieve a phosphorus recovery rate of over 95% from the mother liquor and a total phosphorus utilization rate of 99.9% in the synthesis of ferric phosphate.

[0008] This utility model is achieved through the following technical solution: A phosphorus resource recovery and reuse system for ferric phosphate mother liquor using the disodium hydrogen phosphate method includes an oxidation reactor and a neutralization and adjustment reactor. The oxidation reactor is equipped with a ferrous solution inlet pipe, a mother liquor inlet pipe, a hydrogen peroxide inlet pipe, and a first discharge pipe. A first filter is installed on the first discharge pipe, and a first filtrate pipe is installed on the first filter. The first filtrate pipe is connected to the neutralization and adjustment reactor. The neutralization and adjustment reactor is equipped with an alkali inlet pipe, a PAM inlet pipe, and a second discharge pipe. The second discharge pipe is connected to a reflux sedimentation tank, and the reflux sedimentation tank is connected to a second filter. A second filtrate pipe is installed on the second filter.

[0009] Preferably, both the first filter and the second filter are filter presses.

[0010] Preferably, both the oxidation reactor and the neutralization regulating reactor are equipped with a stirring device.

[0011] Preferably, the reflux sedimentation tank is equipped with an overflow pipe and a sludge pipe; the overflow pipe and the second filtrate pipe are connected to a multi-effect evaporator, and the sludge pipe is connected to a second filter.

[0012] Preferably, a first slurry conveying pump is installed on the first discharge pipe; a filtrate conveying pump is installed on the first filtrate pipe; a second slurry conveying pump is installed on the second discharge pipe; and a sludge pump is installed on the sludge pipe.

[0013] Preferably, the oxidation reactor and the neutralization regulating reactor are respectively equipped with a first pH meter and a second pH meter.

[0014] Preferably, flow meters are installed on the ferrous solution inlet pipe, mother liquor inlet pipe, hydrogen peroxide inlet pipe, alkali inlet pipe and PAM inlet pipe.

[0015] Preferably, the ferrous solution inlet pipe, mother liquor inlet pipe, hydrogen peroxide inlet pipe, first discharge pipe, alkali inlet pipe, PAM inlet pipe and second discharge pipe are all equipped with inlet / outlet valves.

[0016] Compared with the prior art, this utility model has the following advantages and beneficial effects: I. This utility model provides a phosphorus resource recovery and reuse system for ferric phosphate mother liquor produced by the disodium hydrogen phosphate method. The disodium hydrogen phosphate mother liquor flows into an oxidation reactor through a mother liquor inlet pipe. The pH value in the oxidation reactor is adjusted to 1-1.5. Ferrous sulfate solution and hydrogen peroxide are then added through ferrous solution inlet pipe and hydrogen peroxide inlet pipe, respectively. Crude ferric phosphate solution is synthesized in the oxidation reactor. The crude ferric phosphate solution is discharged into a first filter through a first outlet pipe. After filtration, the crude ferric phosphate filter cake is used in an aging step (aging reactor). The first filtrate after filtration is discharged into a neutralization and adjustment reactor through a first filtrate pipe. Sodium hydroxide solution is added to the neutralization and adjustment reactor through an alkali inlet pipe to control the pH in the neutralization and adjustment reactor to 7-8. PAM solution is then added through a PAM inlet pipe to precipitate and remove other metal impurities. The supernatant is used in the sodium sulfate recovery process to recover sodium sulfate. The impurity metal ion content is extremely low. This utility model can achieve a phosphorus recovery rate of over 95% in the mother liquor and a total phosphorus utilization rate of 99.9% in the synthesis of ferric phosphate.

[0017] II. The present invention provides a phosphorus resource recovery and reuse system for iron phosphate mother liquor using the disodium hydrogen phosphate method. The setting of the first pH meter and the second pH meter facilitates the adjustment of the pH of the oxidation reaction vessel and the neutralization adjustment vessel to the optimal pH value.

[0018] III. The present invention provides a phosphorus resource recovery and reuse system for ferric phosphate mother liquor using the disodium hydrogen phosphate method. The setting of the flow meter and the inlet / outlet valve makes the feeding of mother liquor, hydrogen peroxide and ferrous sulfate solution more precise.

[0019] IV. The present invention provides a phosphorus resource recovery and reuse system for ferric phosphate mother liquor produced by the disodium hydrogen phosphate method. The effluent flows into a reflux sedimentation tank through a second discharge pipe. The upper clear liquid flows into a multi-effect evaporator through an overflow pipe. The lower sludge is sent to a second filter. The filtered sludge is sent to a sludge treatment plant. The filtered clear liquid flows into the multi-effect evaporator through a second filtrate pipe. The solid obtained by evaporation in the multi-effect evaporator is dried and then sold as sodium sulfate. The steam obtained by evaporation is condensed to obtain demineralized water, which is then reused in production.

[0020] V. The present invention provides a phosphorus resource recovery and reuse system for iron phosphate mother liquor produced by the disodium hydrogen phosphate method. The first slurry conveying pump, the filtrate conveying pump, the second slurry conveying pump, the reflux sedimentation tank, and the sludge pump provide power to the system to meet production needs. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is a schematic diagram of the structure of Embodiment 2 of this utility model; The components include: 1. Oxidation reactor; 2. Neutralization and adjustment reactor; 3. Ferrous solution inlet pipe; 4. Mother liquor inlet pipe; 6. Hydrogen peroxide inlet pipe; 7. First discharge pipe; 8. First filter; 9. First filtrate pipe; 10. Alkali solution inlet pipe; 11. PAM inlet pipe; 12. Second discharge pipe; 13. First slurry transfer pump; 14. Second filter; 15. Second filtrate pipe; 16. Stirring device; 17. First pH meter; 18. Second pH meter; 19. Flow meter; 20. Inlet / outlet valve; 21. Filtrate transfer pump; 22. Second slurry transfer pump; 23. Reflux sedimentation tank; 24. Overflow pipe; 25. Sludge pipe; 26. Multi-effect evaporator; 27. Sludge pump. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.

[0023] Example 1 like Figure 1 As shown, a phosphorus resource recovery and reuse system for ferric phosphate mother liquor using the disodium hydrogen phosphate method includes an oxidation reactor 1 and a neutralization and adjustment reactor 2. The oxidation reactor 1 is equipped with a ferrous solution inlet pipe 3, a mother liquor inlet pipe 4, a hydrogen peroxide inlet pipe 6, and a first discharge pipe 7. The first discharge pipe 7 is equipped with a first filter 8, and the first filter 8 is equipped with a first filtrate pipe 9, which is connected to the neutralization and adjustment reactor 2. The neutralization and adjustment reactor 2 is equipped with an alkali inlet pipe 10, a PAM inlet pipe 11, and a second discharge pipe 12. The second discharge pipe 12 is connected to a reflux sedimentation tank 23, which is connected to a second filter 14. The second filter 14 is equipped with a second filtrate pipe 15.

[0024] Example 2 like Figure 2As shown, a phosphorus resource recovery and reuse system for ferric phosphate mother liquor using the disodium hydrogen phosphate method includes an oxidation reactor 1 and a neutralization and adjustment reactor 2. The oxidation reactor 1 is equipped with a ferrous solution inlet pipe 3, a mother liquor inlet pipe 4, a hydrogen peroxide inlet pipe 6, and a first discharge pipe 7. The first discharge pipe 7 is equipped with a first filter 8, and the first filter 8 is equipped with a first filtrate pipe 9, which is connected to the neutralization and adjustment reactor 2. The neutralization and adjustment reactor 2 is equipped with an alkali inlet pipe 10, a PAM inlet pipe 11, and a second discharge pipe 12. The second discharge pipe 12 is connected to a reflux sedimentation tank 23, which is connected to a second filter 14. The second filter 14 is equipped with a second filtrate pipe 15.

[0025] Both the first filter 8 and the second filter 14 are filter presses.

[0026] Both the oxidation reactor 1 and the neutralization regulating reactor 2 are equipped with stirring devices 16.

[0027] The reflux sedimentation tank 23 is equipped with an overflow pipe 24 and a sludge pipe 25; the overflow pipe 24 is connected to the second filtrate pipe 15 and then connected to the multi-effect evaporator 26, and the sludge pipe 25 is connected to the second filter 14.

[0028] The first discharge pipe 7 is equipped with a first slurry conveying pump 13; the first filtrate pipe 9 is equipped with a filtrate conveying pump 21; the second discharge pipe 12 is equipped with a second slurry conveying pump 22; and the sludge pipe 25 is equipped with a sludge pump 27.

[0029] The oxidation reactor 1 and the neutralization regulating reactor 2 are respectively equipped with a first pH meter 17 and a second pH meter 18.

[0030] Flow meters 19 are installed on the ferrous solution inlet pipe 3, the mother liquor inlet pipe 4, the hydrogen peroxide inlet pipe 6, the alkali inlet pipe 10, and the PAM inlet pipe 11.

[0031] The ferrous solution inlet pipe 3, the mother liquor inlet pipe 4, the hydrogen peroxide inlet pipe 6, the first discharge pipe 7, the alkali inlet pipe 10, the PAM inlet pipe 11, and the second discharge pipe 12 are all equipped with inlet / outlet valves 20.

[0032] Among them, the first filter 8, the second filter 14, the stirring device 16, the multi-effect evaporator 26, the first slurry conveying pump 13, the filtrate conveying pump 21, the second slurry conveying pump 22, the sludge pump 27, the first pH meter 17, the second pH meter 18, the flow meter 19 and the inlet / outlet valve 20 are all existing technologies and will not be described in detail here.

[0033] Compared with the prior art, this utility model has the following advantages and beneficial effects: I. This utility model provides a phosphorus resource recovery and reuse system for ferric phosphate mother liquor produced by the disodium hydrogen phosphate method. The disodium hydrogen phosphate mother liquor flows into the oxidation reactor 1 through the mother liquor inlet pipe 4. The pH value in the oxidation reactor 1 is adjusted to 1-1.5. Then, ferrous sulfate solution and hydrogen peroxide are added through the ferrous solution inlet pipe 3 and hydrogen peroxide inlet pipe 6, respectively. A crude ferric phosphate solution is synthesized in the oxidation reactor 1. The crude ferric phosphate solution is discharged into the first filter 8 through the first discharge pipe 7. After filtration, the crude ferric phosphate filter cake is used for aging. Step (aging kettle): After filtration, the first filtrate is discharged into the neutralization and adjustment kettle 2 through the first filtrate pipe 9. Sodium hydroxide solution is added to the neutralization and adjustment kettle 2 through the alkali inlet pipe 10 to control the pH of the neutralization and adjustment kettle 2 at 7-8. Then, PAM solution is added through the PAM inlet pipe 11 to precipitate and remove other metal impurities. The supernatant is used for the sodium sulfate recovery process to recover sodium sulfate. The content of impurity metal ions is extremely low. This utility model can achieve a phosphorus recovery rate of over 95% in the mother liquor and a total phosphorus utilization rate of 99.9% in the synthesis of iron phosphate.

[0034] II. The present invention provides a phosphorus resource recovery and reuse system for iron phosphate mother liquor using the disodium hydrogen phosphate method. The first pH meter 17 and the second pH meter 18 facilitate the adjustment of the pH of the oxidation reaction vessel 1 and the neutralization adjustment vessel 2 to the optimal pH value.

[0035] III. The present invention provides a phosphorus resource recovery and reuse system for ferric phosphate mother liquor using the disodium hydrogen phosphate method. The setting of the flow meter 19 and the inlet / outlet valve 20 makes the feeding of mother liquor, hydrogen peroxide and ferrous sulfate solution more precise.

[0036] IV. The present invention provides a phosphorus resource recovery and reuse system for iron phosphate mother liquor produced by the disodium hydrogen phosphate method. The effluent flows into the reflux sedimentation tank 23 through the second discharge pipe 12. The upper clear liquid flows into the multi-effect evaporator 26 through the overflow pipe 24. The lower sludge is sent into the second filter 14. The filtered sludge is sent to the sludge treatment plant. The filtered clear liquid flows into the multi-effect evaporator 26 through the second filtrate pipe 15. The solid obtained by evaporation in the multi-effect evaporator 26 is dried and sold as sodium sulfate. The steam obtained by evaporation is condensed to obtain demineralized water, which is then reused in production.

[0037] V. The present invention provides a phosphorus resource recovery and reuse system for iron phosphate mother liquor produced by the disodium hydrogen phosphate method. The first slurry conveying pump 13, the filtrate conveying pump 21, the second slurry conveying pump 22, the reflux sedimentation tank 23, and the sludge pump 27 provide power to the system to meet production needs.

[0038] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present utility model shall fall within the protection scope of the present utility model.

Claims

1. A system for recovering and reusing phosphorus resources from mother liquor of ferric phosphate produced by the disodium hydrogen phosphate method, characterized in that: The reactor includes an oxidation reactor (1) and a neutralization and adjustment reactor (2). The oxidation reactor (1) is equipped with a ferrous solution inlet pipe (3), a mother liquor inlet pipe (4), a hydrogen peroxide inlet pipe (6), and a first discharge pipe (7). The first discharge pipe (7) is equipped with a first filter (8), and the first filter (8) is equipped with a first filtrate pipe (9). The first filtrate pipe (9) is connected to the neutralization and adjustment reactor (2). The neutralization and adjustment reactor (2) is equipped with an alkali inlet pipe (10), a PAM inlet pipe (11), and a second discharge pipe (12). The second discharge pipe (12) is connected to a reflux sedimentation tank (23). The reflux sedimentation tank (23) is connected to a second filter (14), and the second filter (14) is equipped with a second filtrate pipe (15).

2. The phosphorus resource recovery and reuse system for iron phosphate mother liquor using the disodium hydrogen phosphate method according to claim 1, characterized in that: Both the first filter (8) and the second filter (14) are filter presses.

3. The phosphorus resource recovery and reuse system for ferric phosphate mother liquor using the disodium hydrogen phosphate method according to claim 2, characterized in that: Both the oxidation reactor (1) and the neutralization regulating reactor (2) are equipped with stirring devices (16).

4. The phosphorus resource recovery and reuse system for ferric phosphate mother liquor using the disodium hydrogen phosphate method according to claim 3, characterized in that: The reflux sedimentation tank (23) is equipped with an overflow pipe (24) and a sludge pipe (25); the overflow pipe (24) is connected to the second filtrate pipe (15) and then connected to the multi-effect evaporator (26); the sludge pipe (25) is connected to the second filter (14).

5. The phosphorus resource recovery and reuse system for ferric phosphate mother liquor using the disodium hydrogen phosphate method according to claim 4, characterized in that: A first slurry conveying pump (13) is installed on the first discharge pipe (7); a filtrate conveying pump (21) is installed on the first filtrate pipe (9); a second slurry conveying pump (22) is installed on the second discharge pipe (12); and a sludge pump (27) is installed on the sludge pipe (25).

6. The phosphorus resource recovery and reuse system for ferric phosphate mother liquor using the disodium hydrogen phosphate method according to claim 5, characterized in that: The oxidation reactor (1) and the neutralization regulating reactor (2) are respectively equipped with a first pH meter (17) and a second pH meter (18).

7. A phosphorus resource recovery and reuse system for ferric phosphate mother liquor using the disodium hydrogen phosphate method according to claim 6, characterized in that: Flow meters (19) are installed on the ferrous solution inlet pipe (3), mother liquor inlet pipe (4), hydrogen peroxide inlet pipe (6), alkali inlet pipe (10) and PAM inlet pipe (11).

8. The phosphorus resource recovery and reuse system for iron phosphate mother liquor using the disodium hydrogen phosphate method according to claim 7, characterized in that: The ferrous solution inlet pipe (3), mother liquor inlet pipe (4), hydrogen peroxide inlet pipe (6), first discharge pipe (7), alkali inlet pipe (10), PAM inlet pipe (11) and second discharge pipe (12) are all equipped with inlet / outlet valves (20).

Images