Two-step method iron phosphate aging wastewater resourceful treatment device and method

Abstract

The invention relates to the technical field of new energy material production wastewater treatment, and discloses a two-step method iron phosphate aging wastewater resourceful treatment device and method, and the method comprises the following steps: firstly, intercepting and recovering more than 99% of iron phosphate in two-step mother liquor and two-step washing water by using a polytetrafluoroethylene filter with the filtration precision of 50 nm; secondly, phosphoric acid in the second-step mother liquor is concentrated through an acid-resistant reverse osmosis membrane, and phosphoric acid with the concentration being 8%-12% is recycled; and 3, carrying out two-stage purification on the two-step washing water by using a reverse osmosis membrane to produce pure water with TDS (Total Dissolved Solids) of less than or equal to 2 mg / L and conductivity of less than or equal to 5 [mu] S / cm, thereby realizing resource utilization of iron phosphate, phosphoric acid and pure water in the two-step method iron phosphate aging wastewater.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment in the production of new energy materials, and particularly to a device and method for resource treatment of aged wastewater from the production of iron phosphate by a two-step method. Background Art

[0002] Iron phosphate is an important precursor for the positive electrode material of lithium-ion batteries. The mainstream production of iron phosphate adopts the ammonia process, which uses ferrous sulfate by-produced in the production of titanium dioxide by the sulfuric acid method to react with phosphoric acid or ammonium dihydrogen phosphate, and at the same time adds hydrogen peroxide to oxidize divalent iron to trivalent iron, and then synthesizes iron phosphate; for some manufacturers that use ferrous chloride by-produced in the production of titanium dioxide by the hydrochloric acid method, they use ferrous chloride to react with phosphoric acid or ammonium dihydrogen phosphate, and add hydrogen peroxide to oxidize divalent iron to trivalent iron, and then synthesize iron phosphate; in the production process of iron phosphate, the two-step method of first synthesizing and then aging is a common production process, and phosphoric acid aging is one of the key steps.

[0003] In the aging process of the two-step method for producing iron phosphate, the purpose of phosphoric acid aging is to make the iron phosphate particles grow and dissolve continuously under the conditions of controlling the temperature at 60-90°C, the time at 1 to several hours, and the phosphoric acid concentration at 1-3%, and finally form a stable and uniform crystal structure; the aged iron phosphate is filtered and washed again to remove residual impurities and further purify the iron phosphate product.

[0004] During the aging process of iron phosphate by the two-step method, a high-concentration two-step mother liquor containing a large amount of phosphoric acid and trace metal ions and low-concentration two-step washing water are produced. Resource treatment of the phosphoric acid aging wastewater (two-step mother liquor and two-step washing water) can not only reduce environmental pollution but also realize the recycling of phosphoric acid, further improving the economy and sustainability of the iron phosphate production project by the two-step method. At present, some solutions given by existing patented technologies still need to be improved. For example, in the patent with the patent number 202310646485.0 and the patent name "A method for recycling phosphorus elements in the production process of iron phosphate", when preparing the dihydrate iron phosphate slurry, the mother liquor replacement is directly carried out on the dihydrate iron phosphate filter cake, and then the dihydrate iron phosphate slurry is subjected to multi-stage reverse washing to recover the mother liquor and the first washing water for use in acid preparation, acid supplementation, and water supplementation. The mother liquor and washing water are directly used without concentration and purification, making it difficult to balance the water quality and quantity. For the aging mother liquor containing high concentrations of phosphate, sulfate, and ammonium ions produced during the production of iron phosphate using ferrous sulfate, there is a patent with the patent number 202211172930.6 and the patent name "A resource treatment process for aging mother liquor in the production process of iron phosphate". First, pretreatment is used to remove metal impurities in the aging mother liquor and perform concentration reduction, then iron salts are used to generate iron phosphate, and finally ammonium sulfate is crystallized by evaporation. It is not suitable for the direct recycling of phosphoric acid in the aging wastewater of iron phosphate by the two-step method. For the iron phosphate mother liquor wastewater, there is a patent with the patent number 202211082185.6 and the patent name "A method and system for treating iron phosphate mother liquor wastewater". The synthetic mother liquor and aging mother liquor in the production of iron phosphate are mixed, and magnesium ammonium phosphate is recovered by ammonia addition reaction precipitation. However, the market prospect of magnesium ammonium phosphate as a slow-release fertilizer is poor. Additionally, for the aging mother liquor containing a large amount of dilute phosphoric acid, a small amount of heavy metals, and sodium sulfate produced by the sodium method of iron phosphate, there is a patent with the patent number 202121565236.1 and the patent name "A resource treatment device for aging mother liquor in the production of sodium method iron phosphate". Phosphoric acid iron is directly recovered by ultrafiltration membrane filtration, and then phosphoric acid is concentrated and recovered by acid-resistant reverse osmosis, lacking the concentration and deep purification of the two-step washing water for the aging of phosphoric acid iron. In view of the characteristics of the aging wastewater of iron phosphate by the two-step method, which contains a large amount of phosphoric acid and trace metal ions, and combining the problems of difficult balance of water quality and quantity, difficult direct recovery of phosphoric acid, difficult sales of the produced slow-release fertilizer magnesium ammonium phosphate, and lack of concentration and deep purification of the two-step washing water for the aging of phosphoric acid iron in the existing relevant patents, a new solution for the resource treatment of the aging wastewater of iron phosphate by the two-step method (divided into two-step washing water and two-step mother liquor) is provided. Summary of the Invention

[0005] Aiming at the above-mentioned existing technical deficiencies, the technical problem to be solved by the present invention is to provide a device and method for resource treatment of the aging wastewater of iron phosphate by the two-step method, aiming to realize the resource utilization of iron phosphate, phosphoric acid, and pure water in the aging wastewater of iron phosphate by the two-step method.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions: The present invention provides a two-step resource treatment device for aged wastewater of iron phosphate, including: mother liquor treatment system, acid-resistant reverse osmosis security filter, acid-resistant reverse osmosis high-pressure pump, acid-resistant reverse osmosis device, recovered acid tank, recovered phosphoric acid transfer pump, washing water adjustment tank, washing water filtration pump, washing water filter, washing water sludge tank, washing water sludge pump, washing water sludge filter press, washing water intermediate water tank, washing water booster pump, primary reverse osmosis security filter, primary reverse osmosis high-pressure pump, primary reverse osmosis device, primary reverse osmosis concentrated water tank, concentrated water reverse osmosis booster pump, concentrated water reverse osmosis security filter, concentrated water reverse osmosis high-pressure pump, concentrated water reverse osmosis device, primary reverse osmosis product water tank, secondary reverse osmosis booster pump, secondary reverse osmosis security filter, secondary reverse osmosis high-pressure pump, secondary reverse osmosis device, pure water tank and pure water transfer pump; The mother liquor treatment system is connected to the water inlet of the acid-resistant reverse osmosis device through the acid-resistant reverse osmosis security filter and the acid-resistant reverse osmosis high-pressure pump. The product water outlet of the acid-resistant reverse osmosis device is connected to the 2# water inlet of the primary reverse osmosis concentrated water tank. The concentrated water outlet of the acid-resistant reverse osmosis device is connected to the acid inlet of the recovered acid tank. The acid outlet of the recovered acid tank is sent out the recovered phosphoric acid through the recovered phosphoric acid transfer pump; The two-step washing water is connected to the 1# water inlet of the washing water adjustment tank. The water outlet of the washing water adjustment tank is connected to the water inlet of the washing water filter through the washing water filtration pump. The water outlet of the washing water filter is connected to the 1# water inlet of the washing water intermediate water tank. The sludge discharge port of the washing water filter is connected to the sludge inlet of the washing water sludge tank. The sludge outlet of the washing water sludge tank is connected to the sludge inlet of the washing water sludge filter press through the washing water sludge pump. The filtrate outlet of the washing water sludge filter press is connected to the 2# water inlet of the washing water adjustment tank. The sludge outlet of the washing water sludge filter press sends out the washing water filter cake; The water outlet of the washing water intermediate water tank is successively connected to the water inlet of the primary reverse osmosis device through the washing water booster pump, the primary reverse osmosis security filter and the primary reverse osmosis high-pressure pump. The concentrated water outlet of the primary reverse osmosis device is connected to the 1# water inlet of the primary reverse osmosis concentrated water tank. The water outlet of the primary reverse osmosis concentrated water tank is successively connected to the water inlet of the concentrated water reverse osmosis device through the concentrated water reverse osmosis booster pump, the concentrated water reverse osmosis security filter and the concentrated water reverse osmosis high-pressure pump. The concentrated water outlet of the concentrated water reverse osmosis device is connected to the mother liquor treatment system. The product water outlet of the concentrated water reverse osmosis device is connected to the 2# water inlet of the washing water intermediate water tank; The product water outlet of the primary reverse osmosis device is connected to the water inlet of the primary reverse osmosis product water tank. The water outlet of the primary reverse osmosis product water tank is successively connected to the water inlet of the secondary reverse osmosis device through the secondary reverse osmosis booster pump, the secondary reverse osmosis security filter and the secondary reverse osmosis high-pressure pump. The concentrated water outlet of the secondary reverse osmosis device is connected to the 3# water inlet of the washing water intermediate water tank. The product water outlet of the secondary reverse osmosis device is connected to the water inlet of the pure water tank. The water outlet of the pure water tank is sent out pure water through the pure water transfer pump.

[0007] Further, the mother liquor treatment system includes: a mother liquor regulating tank, a mother liquor filtration pump, a mother liquor filter, a mother liquor sludge tank, a mother liquor sludge pump, a mother liquor sludge filter press, a mother liquor intermediate water tank, and a mother liquor booster pump; Among them, the secondary mother liquor is connected to the 1# water inlet of the mother liquor regulating tank. The water outlet of the mother liquor regulating tank is connected to the water inlet of the mother liquor filter through the mother liquor filtration pump. The water outlet of the mother liquor filter is connected to the 1# water inlet of the mother liquor intermediate water tank. The sludge discharge port of the mother liquor filter is connected to the sludge inlet of the mother liquor sludge tank. The sludge outlet of the mother liquor sludge tank is connected to the sludge inlet of the mother liquor sludge filter press through the mother liquor sludge pump. The filtrate outlet of the mother liquor sludge filter press is connected to the 2# water inlet of the mother liquor regulating tank. The mud cake of the mother liquor is sent out from the sludge outlet of the mother liquor sludge filter press. The water outlet of the mother liquor intermediate water tank is successively connected to the water inlet of the acid-resistant reverse osmosis device through the mother liquor booster pump, the acid-resistant reverse osmosis security filter, and the acid-resistant reverse osmosis high-pressure pump.

[0008] Further, the concentrated water outlet of the concentrated water reverse osmosis device is connected to the 2# water inlet of the mother liquor intermediate water tank.

[0009] Further, the filter elements of the mother liquor filter and the washing water filter are made of PTFE material with a filtration accuracy of 50 nm, so as to effectively intercept and recover more than 99% of the iron phosphate in the mother liquor and the washing water.

[0010] Further, the acid-resistant reverse osmosis device uses a spiral wound acid-resistant polyamide composite membrane. The desalination rate of a single RO membrane is 99.7%, and the maximum working pressure is 83.3 bar, concentrating phosphoric acid to 8% - 12%.

[0011] The treatment method of the two-step iron phosphate aging wastewater resource treatment device includes the following steps: (1) Two-step washing water filtration treatment: effectively intercept and recover more than 99% of the iron phosphate in the two-step washing water through a washing water filter with a filtration accuracy of 50 nm; (2) Two-step washing water purification and concentration treatment: deeply purify the pre-filtered two-step washing water through two-stage reverse osmosis to produce pure water with TDS ≤ 2 mg / L and conductivity ≤ 5 μS / cm, effectively recover water resources, and at the same time use the concentrated water reverse osmosis to further concentrate the concentrated water of the first-stage reverse osmosis; (3) Two-step mother liquor filtration treatment: effectively intercept and recover more than 99% of the iron phosphate in the two-step mother liquor through a mother liquor filter with a filtration accuracy of 50 nm; (4) Two-step mother liquor phosphoric acid concentration treatment: concentrate the pre-filtered two-step mother liquor to a phosphoric acid content of 8% - 12% through acid-resistant reverse osmosis to realize the resource utilization of phosphoric acid.

[0012] Further, the two-step washing water filtration treatment in step (1) includes a washing water regulating tank, a washing water filtration pump, a washing water filter, a washing water sludge tank, a washing water sludge pump, a washing water sludge filter press, and a washing water intermediate water tank; the washing water regulating tank is used to adjust the water quality and water volume of the two-step washing water, and the washing water filter with a filtration accuracy of 50 nm is used to effectively intercept iron phosphate in the two-step washing water, filtering the suspended solid content of the two-step washing water from 50 - 100 mg / L to less than 0.5 mg / L. The sludge discharge of the washing water filter is pressed out as washing water filter cake through the washing water sludge tank, the washing water sludge pump, and the washing water sludge filter press, effectively recovering more than 99% of the iron phosphate in the two-step washing water.

[0013] Further, the two-step washing water purification and concentration treatment in step (2) includes a washing water booster pump, a primary reverse osmosis security filter, a primary reverse osmosis high-pressure pump, a primary reverse osmosis device, a primary reverse osmosis concentrated water tank, a concentrated water reverse osmosis booster pump, a concentrated water reverse osmosis security filter, a concentrated water reverse osmosis high-pressure pump, a concentrated water reverse osmosis device, a primary reverse osmosis product water tank, a secondary reverse osmosis booster pump, a secondary reverse osmosis security filter, a secondary reverse osmosis high-pressure pump, a secondary reverse osmosis device, a pure water tank, and a pure water transfer pump; two-stage purification is carried out through reverse osmosis. First, the TDS content of the pre-filtered two-step washing water is reduced from 600 - 1000 mg / L to TDS ≤ 20 mg / L by the primary reverse osmosis, and then pure water with TDS ≤ 2 mg / L and conductivity ≤ 5 μS / cm is produced by the secondary reverse osmosis, effectively recovering water resources. At the same time, the TDS of the primary reverse osmosis concentrated water is concentrated from 2400 - 5000 mg / L to TDS ≥ 10000 mg / L by the concentrated water reverse osmosis and treated together with the pre-filtered two-step mother liquor. The TDS of the concentrated water reverse osmosis product water is 120 - 500 mg / L and is returned to the washing water intermediate water tank for treatment.

[0014] Further, the two-step mother liquor filtration treatment in step (3) includes a mother liquor regulating tank, a mother liquor filtration pump, a mother liquor filter, a mother liquor sludge tank, a mother liquor sludge pump, a mother liquor sludge filter press, and a mother liquor intermediate water tank; the mother liquor regulating tank is used to adjust the water quality and water volume of the two-step mother liquor, and the mother liquor filter with a filtration accuracy of 50 nm is used to effectively intercept iron phosphate in the two-step mother liquor, filtering the suspended solid content of the two-step mother liquor from 100 - 500 mg / L to less than 1 mg / L. The sludge discharge of the mother liquor filter is pressed out as mother liquor filter cake through the mother liquor sludge tank, the mother liquor sludge pump, and the mother liquor sludge filter press, effectively recovering more than 99% of the iron phosphate in the two-step mother liquor.

[0015] Further, the phosphoric acid concentration treatment of the secondary mother liquor in step (4) includes using a mother liquor booster pump, an acid-resistant reverse osmosis security filter, an acid-resistant reverse osmosis high-pressure pump, an acid-resistant reverse osmosis device, a recovered acid tank, and a recovered phosphoric acid transfer pump; the phosphoric acid content in the pre-filtered secondary mother liquor is concentrated from 10,000 - 30,000 mg / L to 8% - 12% through acid-resistant reverse osmosis composed of a spiral-wound acid-resistant polyamide composite membrane, realizing the resource utilization of phosphoric acid in the aged wastewater of iron phosphate by the two-step method. The phosphoric acid concentration in the acid-resistant reverse osmosis produced water is 2,000 - 6,000 mg / L, which is returned to the first-stage reverse osmosis concentrated water tank for treatment.

[0016] The beneficial effects of the present invention are as follows: Firstly, the present invention uses a polytetrafluoroethylene filter with a filtration accuracy of 50 nm to intercept and recover more than 99% of iron phosphate in the secondary mother liquor and secondary washing water; secondly, it uses an acid-resistant reverse osmosis membrane to concentrate phosphoric acid in the secondary mother liquor to recover phosphoric acid with a concentration of 8% - 12%; thirdly, it uses a reverse osmosis membrane to perform two-stage purification on the secondary washing water to produce pure water with TDS ≤ 2 mg / L and conductivity ≤ 5 μS / cm, realizing the resource utilization of iron phosphate, phosphoric acid, and pure water in the aged wastewater of iron phosphate by the two-step method. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0018] Figure 1 It is a schematic diagram of the system structure of the device for resource treatment of aged wastewater of iron phosphate by the two-step method provided by the embodiment of the present invention.

[0019] In the attached drawings, ML represents the secondary mother liquor, MLBT represents the mother liquor regulating tank, P2 represents the mother liquor filtration pump, MLFS represents the mother liquor filter, MLST represents the mother liquor sludge tank, P4 represents the mother liquor sludge pump, MLBF represents the mother liquor sludge filter press, MLSC represents the mother liquor cake; MLMT represents the mother liquor intermediate water tank, P6 represents the mother liquor booster pump, SAF4 represents the acid-resistant reverse osmosis security filter, HP4 represents the acid-resistant reverse osmosis high-pressure pump, AROS represents the acid-resistant reverse osmosis device, CAT represents the recovered acid tank, P10 represents the recovered phosphoric acid delivery pump, RUPA represents the recovered phosphoric acid; WW represents the secondary washing water, WWBT represents the washing water regulating tank, P1 represents the washing water filtration pump, WWFS represents the washing water filter, WWST represents the washing water sludge tank, P3 represents the washing water sludge pump, WWBF represents the washing water sludge filter press, WWSC represents the washing water cake; WWMT represents the washing water intermediate water tank, P5 represents the washing water booster pump, SAF1 represents the first-stage reverse osmosis security filter, HP1 represents the first-stage reverse osmosis high-pressure pump, ROS1 represents the first-stage reverse osmosis device, CWT1 represents the first-stage reverse osmosis concentrated water tank, P8 represents the concentrated water reverse osmosis booster pump, SAF3 represents the concentrated water reverse osmosis security filter, HP3 represents the concentrated water reverse osmosis high-pressure pump, CROS represents the concentrated water reverse osmosis device, PWT1 represents the first-stage reverse osmosis product water tank, P7 represents the second-stage reverse osmosis booster pump, SAF2 represents the second-stage reverse osmosis security filter, HP2 represents the second-stage reverse osmosis high-pressure pump, ROS2 represents the second-stage reverse osmosis device, PWT represents the pure water tank, P9 represents the pure water delivery pump, PW represents the pure water. Detailed implementation mode

[0020] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. Embodiment

[0021] Such as Figure 1As shown in the figure, this embodiment provides a two-step resource treatment device for aging wastewater of iron phosphate, including: mother liquor adjustment tank MLBT, mother liquor filtration pump P2, mother liquor filter MLFS, mother liquor sludge tank MLST, mother liquor sludge pump P4, mother liquor sludge filter press MLBF, mother liquor intermediate water tank MLMT, mother liquor booster pump P6, acid-resistant reverse osmosis security filter SAF4, acid-resistant reverse osmosis high-pressure pump HP4, acid-resistant reverse osmosis device AROS, recycled acid tank CAT, recycled phosphoric acid delivery pump P10, washing water adjustment tank WWBT, washing water filtration pump P1, washing water filter WWFS, washing water sludge tank WWST, washing water sludge pump P3, washing water sludge filter press WWBF, washing water intermediate water tank WWMT, washing water booster pump P5, primary reverse osmosis security filter SAF1, primary reverse osmosis high-pressure pump HP1, primary reverse osmosis device ROS1, primary reverse osmosis concentrated water tank CWT1, concentrated water reverse osmosis booster pump P8, concentrated water reverse osmosis security filter SAF3, concentrated water reverse osmosis high-pressure pump HP3, concentrated water reverse osmosis device CROS, primary reverse osmosis product water tank PWT1, secondary reverse osmosis booster pump P7, secondary reverse osmosis security filter SAF2, secondary reverse osmosis high-pressure pump HP2, secondary reverse osmosis device ROS2, pure water tank PWT, pure water delivery pump P9; wherein the two-step mother liquor ML is connected to the 1# water inlet of the mother liquor adjustment tank MLBT, the water outlet of the mother liquor adjustment tank MLBT is connected to the water inlet of the mother liquor filter MLFS through the mother liquor filtration pump P2, the water outlet of the mother liquor filter MLFS is connected to the 1# water inlet of the mother liquor intermediate water tank MLMT, the sludge discharge port of the mother liquor filter MLFS is connected to the sludge inlet of the mother liquor sludge tank MLST, the sludge outlet of the mother liquor sludge tank MLST is connected to the sludge inlet of the mother liquor sludge filter press MLBF through the mother liquor sludge pump P4, the filtrate outlet of the mother liquor sludge filter press MLBF is connected to the 2# water inlet of the mother liquor adjustment tank MLBT, and the sludge outlet of the mother liquor sludge filter press MLBF sends out the mother liquor sludge cake MLSC; the water outlet of the mother liquor intermediate water tank MLMT is successively connected to the water inlet of the acid-resistant reverse osmosis device AROS through the mother liquor booster pump P6, the acid-resistant reverse osmosis security filter SAF4, and the acid-resistant reverse osmosis high-pressure pump HP4, the product water outlet of the acid-resistant reverse osmosis device AROS is connected to the 2# water inlet of the primary reverse osmosis concentrated water tank CWT1, the concentrated water outlet of the acid-resistant reverse osmosis device AROS is connected to the acid inlet of the recycled acid tank CAT, and the acid outlet of the recycled acid tank CAT sends out the recycled phosphoric acid RUPA through the recycled phosphoric acid delivery pump P10;The two-step washing water WW is connected to the 1# inlet of the washing water adjustment tank WWBT. The outlet of the washing water adjustment tank WWBT is connected to the inlet of the washing water filter WWFS through the washing water filtration pump P1. The outlet of the washing water filter WWFS is connected to the 1# inlet of the washing water intermediate water tank WWMT. The sludge discharge port of the washing water filter WWFS is connected to the sludge inlet of the washing water sludge tank WWST. The sludge outlet of the washing water sludge tank WWST is connected to the sludge inlet of the washing water sludge filter press WWBF through the washing water sludge pump P3. The filtrate outlet of the washing water sludge filter press WWBF is connected to the 2# inlet of the washing water adjustment tank WWBT. The sludge cake WWSC of the washing water is sent out from the sludge outlet of the washing water sludge filter press WWBF. The outlet of the washing water intermediate water tank WWMT is successively connected to the inlet of the first-stage reverse osmosis device ROS1 through the washing water booster pump P5, the first-stage reverse osmosis security filter SAF1, and the first-stage reverse osmosis high-pressure pump HP1. The concentrated water outlet of the first-stage reverse osmosis device ROS1 is connected to the 1# inlet of the first-stage reverse osmosis concentrated water tank CWT1. The outlet of the first-stage reverse osmosis concentrated water tank CWT1 is successively connected to the inlet of the concentrated water reverse osmosis device CROS through the concentrated water reverse osmosis booster pump P8, the concentrated water reverse osmosis security filter SAF3, and the concentrated water reverse osmosis high-pressure pump HP3. The concentrated water outlet of the concentrated water reverse osmosis device CROS is connected to the 2# inlet of the mother liquor intermediate water tank MLMT. The produced water outlet of the concentrated water reverse osmosis device CROS is connected to the 2# inlet of the washing water intermediate water tank WWMT. The produced water outlet of the first-stage reverse osmosis device ROS1 is connected to the inlet of the first-stage reverse osmosis produced water tank PWT1. The outlet of the first-stage reverse osmosis produced water tank PWT1 is successively connected to the inlet of the second-stage reverse osmosis device ROS2 through the second-stage reverse osmosis booster pump P7, the second-stage reverse osmosis security filter SAF2, and the second-stage reverse osmosis high-pressure pump HP2. The concentrated water outlet of the second-stage reverse osmosis device ROS2 is connected to the 3# inlet of the washing water intermediate water tank WWMT. The produced water outlet of the second-stage reverse osmosis device ROS2 is connected to the inlet of the pure water tank PWT. The pure water PW is sent out through the pure water delivery pump P9.;

[0022] Specifically, this embodiment also provides a two-step method for resource treatment of iron phosphate aging wastewater, including the following steps: (1) Two-step washing water filtration treatment: The washing water filter with a filtration accuracy of 50 nm effectively intercepts and recovers more than 99% of the iron phosphate in the two-step washing water.

[0023] (2) Two-step washing water purification and concentration treatment: The pre-filtered two-step washing water is deeply purified through two-stage reverse osmosis to produce pure water with TDS ≤ 2 mg / L and conductivity ≤ 5 μS / cm, effectively recovering water resources. At the same time, the concentrated water of the first-stage reverse osmosis is further concentrated by the concentrated water reverse osmosis.

[0024] (3) Two-step mother liquor filtration treatment: By using a mother liquor filter with a filtration accuracy of 50 nm, more than 99% of the iron phosphate in the two-step mother liquor can be effectively intercepted and recovered.

[0025] (4) Two-step mother liquor phosphoric acid concentration treatment: Through acid-resistant reverse osmosis, the pre-filtered two-step mother liquor is concentrated to a phosphoric acid content of 8% - 12%, realizing the resource utilization of phosphoric acid.

[0026] Step (1) Two-step washing water filtration treatment, including using a washing water adjustment tank, a washing water filtration pump, a washing water filter, a washing water sludge tank, a washing water sludge pump, a washing water sludge filter press, and a washing water intermediate water tank. Specifically, the washing water adjustment tank is used to adjust the water quality and quantity of the two-step washing water. The washing water filter with a filtration accuracy of 50 nm is used to effectively intercept the iron phosphate in the two-step washing water, and the suspended solid content of the two-step washing water is filtered from 50 - 100 mg / L to less than 0.5 mg / L. The sludge discharged from the washing water filter is pressed out of the washing water filter cake through the washing water sludge tank, the washing water sludge pump, and the washing water sludge filter press, and more than 99% of the iron phosphate in the two-step washing water is effectively recovered.

[0027] Step (2) Two-step washing water purification and concentration treatment, including using a washing water booster pump, a primary reverse osmosis security filter, a primary reverse osmosis high-pressure pump, a primary reverse osmosis device, a primary reverse osmosis concentrated water tank, a concentrated water reverse osmosis booster pump, a concentrated water reverse osmosis security filter, a concentrated water reverse osmosis high-pressure pump, a concentrated water reverse osmosis device, a primary reverse osmosis product water tank, a secondary reverse osmosis booster pump, a secondary reverse osmosis security filter, a secondary reverse osmosis high-pressure pump, a secondary reverse osmosis device, a pure water tank, and a pure water transfer pump. Specifically, two-stage purification is carried out through reverse osmosis. First, the TDS content of the pre-filtered two-step washing water is reduced from 600 - 1000 mg / L to TDS ≤ 20 mg / L by using the primary reverse osmosis, and then pure water with TDS ≤ 2 mg / L and conductivity ≤ 5 μS / cm is produced by using the secondary reverse osmosis, effectively recovering water resources. At the same time, the TDS of the concentrated water from the primary reverse osmosis is concentrated from 2400 - 5000 mg / L to TDS ≥ 10000 mg / L by using the concentrated water reverse osmosis and is treated together with the pre-filtered two-step mother liquor. The TDS of the concentrated water reverse osmosis product water is 120 - 500 mg / L and is returned to the washing water intermediate water tank for treatment.

[0028] Step (3) Filtration treatment of the secondary mother liquor, including using a mother liquor regulation tank, a mother liquor filtration pump, a mother liquor filter, a mother liquor sludge tank, a mother liquor sludge pump, a mother liquor sludge filter press, and a mother liquor intermediate water tank. Specifically, the mother liquor regulation tank is used to adjust the water quality and quantity of the secondary mother liquor. The mother liquor filter with a filtration accuracy of 50 nm effectively intercepts ferric phosphate in the secondary mother liquor, filtering the suspended solids content of the secondary mother liquor from 100 - 500 mg / L to less than 1 mg / L. The sludge discharged from the mother liquor filter is pressed into mother liquor filter cakes through the mother liquor sludge tank, the mother liquor sludge pump, and the mother liquor sludge filter press, effectively recovering more than 99% of the ferric phosphate in the secondary mother liquor.

[0029] Step (4) Phosphoric acid concentration treatment of the secondary mother liquor, including a mother liquor booster pump, an acid-resistant reverse osmosis pre-filter, an acid-resistant reverse osmosis high-pressure pump, an acid-resistant reverse osmosis device, a recovered acid tank, and a recovered phosphoric acid transfer pump. Specifically, the phosphoric acid content in the pre-filtered secondary mother liquor is concentrated from 10,000 - 30,000 mg / L to 8% - 12% through the acid-resistant reverse osmosis composed of a spiral-wound acid-resistant polyamide composite membrane, realizing the resource utilization of phosphoric acid in the aged wastewater of ferric phosphate by the two-step method. The phosphoric acid concentration in the acid-resistant reverse osmosis produced water is 2,000 - 6,000 mg / L, which is returned to the first-stage reverse osmosis concentrated water tank for treatment. Example

[0030] This example is the second example of the present invention. The difference between this example and the first example is that it provides a verification test of the resource treatment device and method for the aged wastewater of ferric phosphate by the two-step method, verifying and explaining the technical effects adopted in this method.

[0031] A new energy material enterprise has built a 25,000-ton annual production line of ferric phosphate by the two-step method. The raw material uses ferrous chloride by-produced from titanium dioxide chloride production. Hydrogen peroxide is used to oxidize ferrous iron to ferric iron, which reacts with phosphoric acid and ammonium dihydrogen phosphate to synthesize ferric phosphate. In the second step of aging, phosphoric acid is used. During the aging process of ferric phosphate, a large amount of secondary mother liquor and secondary washing water containing phosphoric acid are generated. Using the resource treatment technology for the aged wastewater of ferric phosphate by the two-step method given in this patent, a treatment system for the aged wastewater of ferric phosphate by the two-step method is constructed.

[0032] The basic technical parameters of the treatment system for the aged wastewater of ferric phosphate by the two-step method are as follows: System influent water quality and quantity The wastewater quality and quantity of the ferric phosphate aging system by the two-step method are shown in Table 1 below: Table 1: Wastewater quality and quantity of the ferric phosphate aging system by the two-step method.

[0033]

[0034] Note: The amounts of other ions are very small and not listed.

[0035] Two-step Ferric Phosphate Aging Wastewater Treatment System The resource treatment process of two-step ferric phosphate aging wastewater is as follows: Firstly, the two-step washing water is adjusted in the washing water adjustment tank for water quality and quantity, and then successively passes through the washing water filtration pump and the washing water filter to intercept the suspended solids in the two-step washing water. The backwash sludge of the washing water filter passes through the washing water sludge tank, the washing water sludge pump, and the washing water filter press to recover ferric phosphate; the filtered two-step washing water, the concentrated water of the second-stage reverse osmosis, and the produced water of the concentrated water reverse osmosis enter the washing water intermediate water tank, and then successively pass through the washing water booster pump, the first-stage reverse osmosis security filter, the first-stage reverse osmosis high-pressure pump, and the first-stage reverse osmosis for preliminary purification. The produced water of the first-stage reverse osmosis then successively passes through the second-stage reverse osmosis booster pump, the second-stage reverse osmosis security filter, the second-stage reverse osmosis high-pressure pump, and the second-stage reverse osmosis for deep purification. The pure water produced by the second-stage reverse osmosis passes through the pure water tank and the pure water transfer pump for reuse; the concentrated water of the first-stage reverse osmosis and the produced water of the acid-resistant reverse osmosis enter the first-stage reverse osmosis concentration tank, and successively pass through the concentrated water reverse osmosis booster pump, the concentrated water reverse osmosis security filter, the concentrated water reverse osmosis high-pressure pump, and the concentrated water reverse osmosis for concentration; the two-step mother liquor firstly passes through the mother liquor adjustment tank for water quality and quantity adjustment, and then passes through the mother liquor filtration pump and the mother liquor filter to intercept the suspended solids in the two-step mother liquor. The backwash sludge of the mother liquor filter passes through the mother liquor sludge tank, the mother liquor sludge pump, and the mother liquor filter press to recover ferric phosphate; the filtered two-step mother liquor and the concentrated water of the concentrated water reverse osmosis enter the mother liquor intermediate water tank, and finally successively pass through the mother liquor booster pump, the acid-resistant reverse osmosis security filter, the acid-resistant reverse osmosis high-pressure pump, and the acid-resistant reverse osmosis for concentration. The concentrated acid-resistant reverse osmosis is recycled through the recovered acid tank and the recovered phosphoric acid transfer pump to recover phosphoric acid; in addition, the system is equipped with a dosing device and a reverse osmosis chemical cleaning device.

[0036] Treatment Effect of System Equipment The treatment effects of each equipment of the two-step ferric phosphate aging system are shown in Table 2 below: Table 2: Treatment Effects of Each Equipment of the Two-step Ferric Phosphate Aging System.

[0037]

[0038] Note: The influent of the first-stage reverse osmosis in the table includes the two-step washing water after pre-filtration, the concentrated water of the second-stage reverse osmosis, and the produced water of the concentrated water reverse osmosis. The influent of the second-stage reverse osmosis is the produced water of the first-stage reverse osmosis. The influent of the concentrated water reverse osmosis is composed of the concentrated water of the first-stage reverse osmosis and the produced water of the acid-resistant reverse osmosis. The influent of the acid-resistant reverse osmosis includes the two-step mother liquor after pre-filtration and the concentrated water of the concentrated water reverse osmosis.

[0039] Main Equipment of the System The main equipment of the two-step ferric phosphate aging system is shown in Table 3 below: Table 3: Main Equipment of the Two-step Ferric Phosphate Aging System.

[0040]

[0041]

[0042]

[0043]

[0044] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. Two-step resource treatment device for aged wastewater of iron phosphate, characterized in that, Including: Mother liquor treatment system, acid-resistant reverse osmosis security filter, acid-resistant reverse osmosis high-pressure pump, acid-resistant reverse osmosis device, recycled acid tank, recycled phosphoric acid transfer pump, washing water adjustment tank, washing water filtration pump, washing water filter, washing water sludge tank, washing water sludge pump, washing water sludge filter press, washing water intermediate water tank, washing water booster pump, primary reverse osmosis security filter, primary reverse osmosis high-pressure pump, primary reverse osmosis device, primary reverse osmosis concentrated water tank, concentrated water reverse osmosis booster pump, concentrated water reverse osmosis security filter, concentrated water reverse osmosis high-pressure pump, concentrated water reverse osmosis device, primary reverse osmosis product water tank, secondary reverse osmosis booster pump, secondary reverse osmosis security filter, secondary reverse osmosis high-pressure pump, secondary reverse osmosis device, pure water tank and pure water transfer pump; The mother liquor treatment system is connected to the water inlet of the acid-resistant reverse osmosis device through the acid-resistant reverse osmosis security filter and the acid-resistant reverse osmosis high-pressure pump. The product water outlet of the acid-resistant reverse osmosis device is connected to the 2# water inlet of the primary reverse osmosis concentrated water tank. The concentrated water outlet of the acid-resistant reverse osmosis device is connected to the acid inlet of the recycled acid tank. The acid outlet of the recycled acid tank is sent out the recycled phosphoric acid through the recycled phosphoric acid transfer pump. The two-step washing water is connected to the 1# water inlet of the washing water adjustment tank. The water outlet of the washing water adjustment tank is connected to the water inlet of the washing water filter through the washing water filtration pump. The water outlet of the washing water filter is connected to the 1# water inlet of the washing water intermediate water tank. The sludge discharge port of the washing water filter is connected to the sludge inlet of the washing water sludge tank. The sludge outlet of the washing water sludge tank is connected to the sludge inlet of the washing water sludge filter press through the washing water sludge pump. The filtrate outlet of the washing water sludge filter press is connected to the 2# water inlet of the washing water adjustment tank. The sludge outlet of the washing water sludge filter press sends out the washing water filter cake. The water outlet of the washing water intermediate water tank is successively connected to the water inlet of the primary reverse osmosis device through the washing water booster pump, the primary reverse osmosis security filter and the primary reverse osmosis high-pressure pump. The concentrated water outlet of the primary reverse osmosis device is connected to the 1# water inlet of the primary reverse osmosis concentrated water tank. The water outlet of the primary reverse osmosis concentrated water tank is successively connected to the water inlet of the concentrated water reverse osmosis device through the concentrated water reverse osmosis booster pump, the concentrated water reverse osmosis security filter and the concentrated water reverse osmosis high-pressure pump. The concentrated water outlet of the concentrated water reverse osmosis device is connected to the mother liquor treatment system. The product water outlet of the concentrated water reverse osmosis device is connected to the 2# water inlet of the washing water intermediate water tank. The product water outlet of the primary reverse osmosis device is connected to the water inlet of the primary reverse osmosis product water tank. The water outlet of the primary reverse osmosis product water tank is successively connected to the water inlet of the secondary reverse osmosis device through the secondary reverse osmosis booster pump, the secondary reverse osmosis security filter and the secondary reverse osmosis high-pressure pump. The concentrated water outlet of the secondary reverse osmosis device is connected to the 3# water inlet of the washing water intermediate water tank. The product water outlet of the secondary reverse osmosis device is connected to the water inlet of the pure water tank. The water outlet of the pure water tank sends out the pure water through the pure water transfer pump.

2. The two-step aging wastewater resource treatment device for iron phosphate as described in claim 1, wherein The mother liquor treatment system includes: mother liquor adjustment tank, mother liquor filtration pump, mother liquor filter, mother liquor sludge tank, mother liquor sludge pump, mother liquor sludge filter press, mother liquor intermediate water tank and mother liquor booster pump; Among them, the secondary mother liquor is connected to the 1# water inlet of the mother liquor adjustment tank. The water outlet of the mother liquor adjustment tank is connected to the water inlet of the mother liquor filter through the mother liquor filtration pump. The water outlet of the mother liquor filter is connected to the 1# water inlet of the intermediate mother liquor water tank. The sludge discharge port of the mother liquor filter is connected to the sludge inlet of the mother liquor sludge tank. The sludge outlet of the mother liquor sludge tank is connected to the sludge inlet of the mother liquor sludge filter press through the mother liquor sludge pump. The filtrate outlet of the mother liquor sludge filter press is connected to the 2# water inlet of the mother liquor adjustment tank. The sludge cake of the mother liquor is sent out from the sludge outlet of the mother liquor sludge filter press. The water outlet of the intermediate mother liquor water tank is successively connected to the water inlet of the acid-resistant reverse osmosis device through the mother liquor booster pump, acid-resistant reverse osmosis security filter, and acid-resistant reverse osmosis high-pressure pump.

3. The two-step iron phosphate aging wastewater resource treatment device according to any one of claims 1 or 2, characterized in that The concentrated water outlet of the concentrated water reverse osmosis device is connected to the 2# water inlet of the intermediate mother liquor water tank.

4. The two-step aging wastewater resource treatment device for iron phosphate as described in claim 1, characterized in that, The filter elements of the mother liquor filter and the washing water filter are made of PTFE material with a filtration accuracy of 50 nm, so as to effectively intercept and recover more than 99% of the iron phosphate in the mother liquor and washing water.

5. The two-step aging wastewater resource treatment device for iron phosphate as described in claim 1, characterized in that, The acid-resistant reverse osmosis device uses a spiral-wound acid-resistant polyamide composite membrane. The desalination rate of a single RO membrane is 99.7%, and the maximum working pressure is 83.3 bar, concentrating the phosphoric acid to 8% - 12%.

6. The treatment method of the two-step aging wastewater resource treatment device for iron phosphate as claimed in claim 1, characterized in that, It includes the following steps: (1) Two-step washing water filtration treatment: More than 99% of the iron phosphate in the two-step washing water is effectively intercepted and recovered through a washing water filter with a filtration accuracy of 50 nm. (2) Two-step washing water purification and concentration treatment: The pre-filtered two-step washing water is deeply purified through two-stage reverse osmosis to produce pure water with TDS ≤ 2 mg / L and conductivity ≤ 5 μS / cm, effectively recovering water resources. At the same time, the concentrated water of the first-stage reverse osmosis is further concentrated by the concentrated water reverse osmosis. (3) Two-step mother liquor filtration treatment: More than 99% of the iron phosphate in the two-step mother liquor is effectively intercepted and recovered through a mother liquor filter with a filtration accuracy of 50 nm. (4) Two-step mother liquor phosphoric acid concentration treatment: The pre-filtered two-step mother liquor is concentrated to a phosphoric acid content of 8% - 12% through acid-resistant reverse osmosis, realizing the resource utilization of phosphoric acid.

7. The treatment method of the two-step aging wastewater resource treatment device for iron phosphate according to claim 6, characterized in that, The two-step washing water filtration treatment in step (1) includes using a washing water adjustment tank, a washing water filtration pump, a washing water filter, a washing water sludge tank, a washing water sludge pump, a washing water sludge filter press, and a washing water intermediate water tank. The washing water adjustment tank is used to adjust the water quality and quantity of the two-step washing water. The iron phosphate in the two-step washing water is effectively intercepted by a washing water filter with a filtration accuracy of 50 nm, and the suspended solid content of the two-step washing water is filtered from 50 - 100 mg / L to less than 0.5 mg / L. The sludge discharged from the washing water filter is pressed out as a washing water filter cake through the washing water sludge tank, the washing water sludge pump, and the washing water sludge filter press, effectively recovering more than 99% of the iron phosphate in the two-step washing water.

8. The treatment method of the two-step iron phosphate aging wastewater resource treatment device according to claim 6, characterized in that, The second-step washing water purification and concentration treatment in step (2) includes using a washing water booster pump, a primary reverse osmosis security filter, a primary reverse osmosis high-pressure pump, a primary reverse osmosis device, a primary reverse osmosis concentrate tank, a concentrate reverse osmosis booster pump, a concentrate reverse osmosis security filter, a concentrate reverse osmosis high-pressure pump, a concentrate reverse osmosis device, a primary reverse osmosis product water tank, a secondary reverse osmosis booster pump, a secondary reverse osmosis security filter, a secondary reverse osmosis high-pressure pump, a secondary reverse osmosis device, a pure water tank, and a pure water transfer pump; two-stage purification is carried out through reverse osmosis. First, the TDS content of the pre-filtered second-step washing water is reduced from 600 - 1000 mg / L to TDS ≤ 20 mg / L by the primary reverse osmosis, and then pure water with TDS ≤ 2 mg / L and conductivity ≤ 5 μS / cm is produced by the secondary reverse osmosis, effectively recovering water resources. At the same time, the TDS of the primary reverse osmosis concentrate is concentrated from 2400 - 5000 mg / L to TDS ≥ 10000 mg / L by the concentrate reverse osmosis and treated together with the pre-filtered second-step mother liquor. The TDS of the concentrate reverse osmosis product water is 120 - 500 mg / L and is returned to the washing water intermediate water tank for treatment.

9. The treatment method of the two-step aging wastewater resource treatment device for iron phosphate according to claim 6, characterized in that, The second-step mother liquor filtration treatment in step (3) includes using a mother liquor adjustment tank, a mother liquor filtration pump, a mother liquor filter, a mother liquor sludge tank, a mother liquor sludge pump, a mother liquor sludge filter press, and a mother liquor intermediate water tank; the mother liquor adjustment tank is used to adjust the water quality and quantity of the second-step mother liquor, and the mother liquor filter with a filtration accuracy of 50 nm effectively intercepts ferric phosphate in the second-step mother liquor, reducing the suspended solid content of the second-step mother liquor from 100 - 500 mg / L to less than 1 mg / L. The sludge discharge of the mother liquor filter is pressed out as mother liquor filter cake through the mother liquor sludge tank, the mother liquor sludge pump, and the mother liquor sludge filter press, effectively recovering more than 99% of the ferric phosphate in the second-step mother liquor.

10. The treatment method of the two-step iron phosphate aging wastewater resource treatment device according to claim 6, characterized in that, The second-step mother liquor phosphoric acid concentration treatment in step (4) includes using a mother liquor booster pump, an acid-resistant reverse osmosis security filter, an acid-resistant reverse osmosis high-pressure pump, an acid-resistant reverse osmosis device, a recovered acid tank, and a recovered phosphoric acid transfer pump; the phosphoric acid content in the pre-filtered second-step mother liquor is concentrated from 10000 - 30000 mg / L to 8% - 12% through the acid-resistant reverse osmosis composed of a spiral-wound acid-resistant polyamide composite membrane, realizing the resource utilization of phosphoric acid in the two-step ferric phosphate aging wastewater. The phosphoric acid concentration of the acid-resistant reverse osmosis product water is 2000 - 6000 mg / L and is returned to the primary reverse osmosis concentrate tank for treatment.

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