Efficient precipitation treatment process and system for iron phosphate mother liquor wastewater

Abstract

The application discloses a kind of high-efficiency precipitation treatment process and system of iron phosphate mother liquor wastewater, belong to battery raw material grade phosphorus acid iron sewage treatment field, including the following steps: mother liquor and ammonia water are injected into primary mixing pool; pH is adjusted to 6.5~6.8 by mechanical stirring reaction; sludge of flocculation tank and primary sedimentation tank backflow carries out flocculation reaction 30min;Into primary sedimentation tank, the best rising velocity of mother liquor is 0.4m / h~0.6m / h;Part of mother liquor is discharged from effluent area, another part of mother liquor is discharged from bottom sludge concentration area, reduce the sludge amount of primary plate-frame filter press, shorten plate-frame filter press feeding time, bottom concentrated sludge is continuously discharged by sludge backflow pump and primary sludge discharge pump;Part of sludge backflows to flocculation tank, another part of sludge enters primary plate-frame filter press and is dewatered;Backflow sludge and flocculation can be fully mixed to form larger flocculation, and the solid content of sludge is higher after larger flocculation enters primary plate-frame filter press and is filtered again;Primary plate-frame filtrate flows into secondary mixing pool.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of battery raw material grade iron phosphate wastewater treatment, and particularly relates to an efficient precipitation treatment process and system for iron phosphate mother liquor wastewater. BACKGROUND

[0002] The filter press filtrate is the mother liquor of the battery raw material grade iron phosphate production wastewater, about 10% to 20% of iron phosphate is remained in the filter press filtrate, and NH4, Ca, Mg, Zn, Mn, PO4, SO4 and the like are also accompanied, in the general iron phosphate mother liquor wastewater treatment process, by adding ammonia water to adjust the pH, Fe, Zn, Mn, Mg, Ca and the like heavy metal precipitates are generated, the sludge pump is used to send the sludge-water mixture into the plate and frame filter press for pressing, the dry sludge is outsourced for treatment, the filter press filtrate is concentrated to 15% of the salt content through filtration and reverse osmosis membrane, and then evaporation is carried out, and finally the I type product of Fertilizer Grade Ammonium Sulfate GB / T535-2020 is obtained.

[0003] The general treatment process for the mother liquor of the iron phosphate production wastewater includes the direct plate and frame filter pressing method and the traditional precipitation method, the direct plate and frame filter pressing method uses ammonia water to adjust the pH first, and then the plate and frame filter press is directly used to remove the suspended solids, this process has the following shortcomings: 1, all the wastewater with low solid content is treated through the plate and frame filter press, causing long feeding time of the plate and frame filter press; 2, after adding the medicine once to pH 8, the ammonium magnesium phosphate precipitate generated is loose and not easy to precipitate, and is easy to coat various metal precipitates, causing the suspended solids in the effluent to exceed the standard. SUMMARY

[0004] The purpose of the present application is to provide an efficient precipitation treatment process and system for iron phosphate mother liquor wastewater to solve the problems raised in the background.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme: an efficient precipitation treatment process for iron phosphate mother liquor wastewater, comprising the following steps:

[0006] Step S1: the mother liquor and ammonia water react to generate precipitates;

[0007] Step S11: the mother liquor and ammonia water are injected into a primary mixing pool;

[0008] Step S12: the pH is adjusted to 6.5 to 6.8 through mechanical stirring reaction;

[0009] Step S2: flocculation and precipitation;

[0010] Step S21: the flocculation pool and the sludge backflowed from the primary sedimentation pool are subjected to flocculation reaction for 30 minutes;

[0011] Step S22: the primary sedimentation pool is entered, and the optimal upward flow rate of the mother liquor is 0.4 m / h to 0.6 m / h.

[0012] Step S23: The bottom concentrated sludge is continuously discharged to the first plate and frame filter press by a first sludge discharge pump;

[0013] Step S24: A part of the sludge is backflowed to the flocculation tank, and the cycle S2, and another part enters the first plate and frame filter press for dewatering; the filter press liquid flows into the second mixed tank;

[0014] Step S3: Second mixed and sedimentation;

[0015] Step S31: The supernatant of the first sedimentation tank and the filter press liquid of the first plate and frame filter press are combined to enter the second mixed tank;

[0016] Step S32: In the second mixed tank, the mechanical stirring reaction is carried out with the added ammonia water to adjust the pH to 8.0~8.5;

[0017] Step S33: Entering the second sedimentation tank, the upward flow rate of the second sedimentation tank is 1.8m / h~2.5m / h

[0018] Step S34: The supernatant of the second sedimentation tank flows into the clean water tank, and the bottom sludge is intermittently discharged to the second plate and frame filter press by a second sludge discharge pump.

[0019] Further, the mechanical stirring in the first mixed tank is carried out with the added ammonia water for 10min~15min.

[0020] Further, the sludge backflow amount control point of the step S24 is 5%~10% of the influent water quantity.

[0021] Further, the dewatered sludge of the first plate and frame filter press can be recycled.

[0022] Further, the mechanical stirring in the second mixed tank is carried out with the added ammonia water for 10min~15min.

[0023] Further, the dewatered sludge of the second plate and frame filter press is disposed as solid waste.

[0024] Further, the first sludge discharge pump works continuously, and the second sludge discharge pump works intermittently.

[0025] Further, the second sludge discharge pump is discharged once every 3~5 hours, and each time for 1.5~2.5 hours.

[0026] The application discloses a high-efficiency precipitation treatment system for iron phosphate mother liquor wastewater.

[0027] Further, the flocculation tank and the first-stage precipitation tank are provided with a sludge backflow pump.

[0028] Compared with the prior art, the application has the following beneficial effects:

[0029] The first-stage precipitation tank adopts a one-in-two-out mode, part of the mother liquor is discharged from a water outlet area, and the other part of the mother liquor is discharged from a bottom sludge concentration area, so that the sludge amount entering the first-stage plate-and-frame filter press is reduced, the feeding time of the plate-and-frame filter press is shortened, the backflow sludge and flocs can be fully mixed to form larger flocs, and the sludge solid content is higher after the larger flocs are filtered by the first-stage plate-and-frame filter press.

[0030] The two-stage reaction precipitation tanks are provided, the pH meter is arranged in the mixing tank to control different pH values to generate sludge with different properties, and the two-stage reaction precipitation tanks are respectively provided with the precipitation tanks to prevent the magnesium ammonium phosphate from coating other metal precipitates and to promote the metal precipitates to be more easily precipitated and suspended to meet the standard;

[0031] The two-stage precipitation tanks are respectively provided with independent plate-and-frame filter presses, the first-stage precipitates can be recycled as slow-release fertilizers, the first-stage precipitation tank adopts the one-in-two-out mode, so that the surface load of the water outlet area of the first-stage precipitation tank is reduced, and the filter pressing liquid of the plate-and-frame filter press is not backflowed to the front end of the precipitation tank, so that the surface load is also reduced. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is a schematic diagram of the high-efficiency precipitation treatment system for iron phosphate mother liquor wastewater.

[0033] In the drawing: 10, first-stage mixing tank; 101, water inlet pipeline; 20, flocculation tank; 30, first-stage precipitation tank; 40, second-stage mixing tank; 50, second-stage precipitation tank; 60, sludge backflow pump; 710, first-stage sludge discharge pump; 720, first-stage plate-and-frame filter press; 810, second-stage sludge discharge pump; 820, second-stage plate-and-frame filter press; 90, clean water tank. DETAILED DESCRIPTION

[0034] The application will be further described below in combination with the embodiments.

[0035] The following embodiments are used to illustrate the application, but cannot be used to limit the protection scope of the application. The conditions in the embodiments can be further adjusted according to specific conditions, and simple improvements of the method of the application under the concept of the application also belong to the protection scope of the application.

[0036] Referring to Figure 1 The application provides a high-efficiency precipitation treatment system for iron phosphate mother liquor wastewater, which comprises a first mixing pool 10, a flocculation pool 20, a first precipitation pool 30, a second mixing pool 40 and a second precipitation pool 50 arranged in sequence, wherein the flocculation pool 20 and the first precipitation pool 30 are provided with a sludge backflow pump 60, the sludge backflow pump 60 transports the sludge-water mixture in the first precipitation pool to the flocculation pool 20, so as to facilitate flocculation of larger flocculation bodies, a first sludge discharge pump 710 and a first plate-and-frame filter press 720 are arranged in parallel between the first precipitation pool 30 and the second mixing pool 40, the first sludge discharge pump 710 transports the sludge-water mixture to the first plate-and-frame filter press 720, the filtrate separated from the first plate-and-frame filter press 720 enters the second mixing pool 40, and a second sludge discharge pump 810 and a second plate-and-frame filter press 820 are arranged in parallel between the second precipitation pool 50 and a clean water pool 90.

[0037] A high-efficiency precipitation treatment process for iron phosphate mother liquor wastewater comprises the following steps:

[0038] Step S1: reacting the mother liquor and ammonia water to generate a precipitate;

[0039] Step S11: injecting the mother liquor and ammonia water into the first mixing pool 10;

[0040] Step S12: adjusting the pH to 6.5-6.8 through mechanical stirring reaction;

[0041] Step S2: flocculation and precipitation;

[0042] Step S21: the flocculation pool 20 and the first precipitation pool 30 backflow 1%-1.5% of sludge with a solid content (the backflow amount of sludge is an optimal control point of 5%-10% of the water inflow amount) to perform a flocculation reaction for 30 min; Step S22: entering the first precipitation pool 30, and the optimal upward flow rate of the mother liquor is 0.4 m / h-0.6 m / h;

[0043] Step S23: the sludge concentrated at the bottom is continuously discharged to the first plate-and-frame filter press 720 through the first sludge discharge pump 710;

[0044] Step S24: part of the sludge is backflowed to the flocculation pool 20, and the circulation S2 is performed, and the other part enters the first plate-and-frame filter press 720 to perform dewatering, the dewatered sludge is recycled as slow-release fertilizer, and the filtrate flows into the second mixing pool 40;

[0045] Step S3: second mixing and precipitation;

[0046] Step S31: the supernatant of the first precipitation pool 30 and the filtrate of the first plate-and-frame filter press 720 are combined to enter the second mixing pool 40;

[0047] Step S32: mechanical stirring reaction with added ammonia water in the secondary mixing tank 40 to adjust the pH to 8.0~8.5;

[0048] Step S33: enter the secondary sedimentation tank 50, the optimal upward flow rate of the secondary sedimentation tank 50 is 1.8m / h~2.5m / h

[0049] Step S34: the supernatant of the secondary sedimentation tank 50 flows into the clear water tank 90, the bottom sludge is intermittently discharged to the secondary plate and frame filter 820 by the secondary sludge discharge pump 810, and the dewatered sludge of the secondary plate and frame filter 820 is disposed as solid waste.

[0050] Process: mother liquor and ammonia water are injected into the primary mixing tank 10, mechanical stirring is performed for 10min~15min to adjust the pH to 6.5~6.8, and trivalent iron and ammonium magnesium phosphate precipitates are generated.

[0051] The flocculation tank 20 and 1%~1.5% of the sludge with solid content rate (the optimal control point of sludge return flow is 5%~10% of the influent water quantity) of the primary sedimentation tank 30 return flow are subjected to flocculation reaction for 30min, flow into the primary sedimentation tank 30, the upward flow rate of the primary sedimentation tank 30 mother liquor is 0.4m / h~0.6m / h, part of the mother liquor is discharged from the effluent area, and the other part of the mother liquor is discharged from the bottom sludge concentration area, which reduces the sludge quantity of the primary plate and frame filter 720 and shortens the plate and frame filter feeding time. The bottom concentrated sludge is continuously discharged through the sludge return pump 60 and the primary sludge discharge pump 710, part of the sludge returns to the flocculation tank 20, and the return sludge and flocculation can fully mix to form larger flocculation, and the other part of the sludge enters the primary plate and frame filter 720. The dewatered sludge of the primary plate and frame filter 720 is recycled as slow-release fertilizer, and the filter press liquid flows into the secondary sedimentation tank 50. The filter press liquid no longer returns to the front end of the primary sedimentation tank 30, thereby reducing the surface load of the primary sedimentation tank 30 effluent area.

[0052] The primary sedimentation tank 30 mother liquor and the primary plate and frame filter 720 filter press liquid converge into the secondary mixing tank 40, and the secondary mixing tank 40 is subjected to mechanical stirring for 10min~15min to adjust the pH to 8.0~8.5 to mainly generate Zn, Mn and other precipitates.

[0053] The optimal upward flow rate of the secondary sedimentation tank 50 is 1.8m / h~2.5m / h, the supernatant of the secondary sedimentation tank 50 flows into the clear water tank 90, the bottom sludge of the secondary sedimentation tank 50 is intermittently discharged to the secondary plate and frame filter 820 by the secondary sludge discharge pump 810, and the dewatered sludge of the secondary plate and frame filter 820 is disposed as solid waste. The filter press liquid no longer returns to the front end of the secondary sedimentation tank 50, but directly enters the clear water tank 90, thereby reducing the surface load of the secondary sedimentation tank 50 effluent area. Example 1

[0054] Mechanical stirring is set to 13 min, the first sedimentation tank 30 mother liquor up flow rate 0.5 m / h, the second sedimentation tank 50 up flow rate 2.1 m / h, the solid content of the reflux sludge is 1.3%, the sludge reflux volume control point is 8% of the influent water quantity, the first mixed tank 10 reaction adjusts PH 6.5, the second mixed tank 40 reaction adjusts PH 8.0, the effluent turbidity is 8.9 NTU. Example 2

[0055] Mechanical stirring is set to 13 min, the first sedimentation tank 30 mother liquor up flow rate 0.5 m / h, the second sedimentation tank 50 up flow rate 2.1 m / h, the solid content of the reflux sludge is 1.3%, the sludge reflux volume control point is 8% of the influent water quantity, the first mixed tank 10 reaction adjusts PH 6.8, the second mixed tank 40 reaction adjusts PH 8.5, the effluent turbidity is 8.3 NTU. Example 3

[0056] Mechanical stirring is set to 13 min, the first sedimentation tank 30 mother liquor up flow rate 0.5 m / h, the second sedimentation tank 50 up flow rate 2.1 m / h, the solid content of the reflux sludge is 1.3%, the sludge reflux volume control point is 8% of the influent water quantity, the first mixed tank 10 reaction adjusts PH 6.7, the second mixed tank 40 reaction adjusts PH 8.3, the effluent turbidity is 7.2 NTU.

[0057] The above examples of the present application are only examples for clearly illustrating the present application, and are not the limitation of the embodiments of the present application. For those skilled in the art, on the basis of the above description, other different forms of changes or variations can be made, and these changes or variations which are obviously extended from the spirit of the present application are still within the protection scope of the present application.

Claims

1. A high-efficiency precipitation treatment process for ferric phosphate mother liquor wastewater, characterized in that, Includes the following steps: Step S1: The mother liquor reacts with ammonia to form a precipitate; Step S11: Inject the mother liquor and ammonia water into the primary mixing tank (10); Step S12: Adjust the pH to 6.5-6.8 by mechanically stirring the reaction mixture; Step S2: Flocculation and sedimentation; Step S21: The sludge returned from the flocculation tank (20) and the primary sedimentation tank (30) undergoes a flocculation reaction for 30 minutes; Step S22: Enter the primary sedimentation tank (30), the upward flow velocity of the mother liquor is 0.4m / h~0.6m / h; Step S23: The concentrated sludge at the bottom is continuously discharged through a sludge return pump (60) and a primary sludge discharge pump (710); Step S24: A portion of the sludge is returned to the flocculation tank (20) and circulated in S2, while the other portion enters the primary plate and frame filter press (720) for dewatering; the filtrate flows into the secondary mixing tank (40), and the sludge return flow rate control point in step S24 is 5% to 10% of the influent flow rate; Step S3: Secondary mixing and precipitation; Step S31: The supernatant from the primary sedimentation tank (30) and the filtrate from the primary plate and frame filter press (720) are combined and enter the secondary mixing tank (40). Step S32: In the secondary mixing tank (40), mechanically stir the added ammonia water to adjust the pH to 8.0~8.5; Step S33: Enter the secondary sedimentation tank (50), the upward flow velocity of the secondary sedimentation tank (50) is 1.8m / h~2.5m / h; Step S34: The upper clear liquid of the secondary sedimentation tank (50) flows into the clear water tank (90), and the bottom sludge is intermittently discharged to the secondary plate and frame filter press (820) through the secondary sludge discharge pump (810).

2. The efficient precipitation treatment process for ferric phosphate mother liquor wastewater according to claim 1, characterized in that: The mixture is mechanically stirred with added ammonia water in the primary mixing tank (10) for 10 to 15 minutes.

3. The efficient precipitation treatment process for ferric phosphate mother liquor wastewater according to claim 1, characterized in that: The dewatered sludge from the primary plate and frame filter press (720) can be recycled.

4. The efficient precipitation treatment process for ferric phosphate mother liquor wastewater according to claim 1, characterized in that: The ammonia water added to the secondary mixing tank (40) is mechanically stirred for 10 to 15 minutes.

5. The efficient precipitation treatment process for ferric phosphate mother liquor wastewater according to claim 1, characterized in that: The dewatered sludge from the secondary plate and frame filter press (820) is disposed of as solid waste.

6. The efficient precipitation treatment process for ferric phosphate mother liquor wastewater according to claim 1, characterized in that: The primary sludge discharge pump operates continuously, while the secondary sludge discharge pump operates intermittently.

7. The efficient precipitation treatment process for ferric phosphate mother liquor wastewater according to claim 6, characterized in that: The secondary sludge discharge pump discharges sludge every 3 to 5 hours, with each discharge lasting 1.5 to 2.5 hours.

8. The system used in the high-efficiency precipitation treatment process for ferric phosphate mother liquor wastewater according to claim 1, characterized in that: It includes a primary mixing tank (10), a flocculation tank (20), a primary sedimentation tank (30), a secondary mixing tank (40), and a secondary sedimentation tank (50). A primary sludge discharge pump (710) and a primary plate and frame filter press (720) are provided as bypasses between the primary sedimentation tank (30) and the secondary mixing tank (40). A secondary sludge discharge pump (810) and a secondary plate and frame filter press (820) are provided as bypasses between the secondary sedimentation tank (50) and the clear water tank (90).

9. The system used in the high-efficiency precipitation treatment process for ferric phosphate mother liquor wastewater according to claim 8, characterized in that: The flocculation tank (20) and the primary sedimentation tank (30) are equipped with sludge return pumps (60).

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