CN113860548A

CN113860548A - Treatment system and treatment method for rinsing water for producing anhydrous iron phosphate

Info

Publication number: CN113860548A
Application number: CN202111141324.3A
Authority: CN
Inventors: 许锦鹏; 何志; 肖松林; 赵聪
Original assignee: Sichuan Sidaneng Environmental Protection Technology Co ltd
Current assignee: Sichuan Sidaneng Environmental Protection Technology Co ltd
Priority date: 2021-09-28
Filing date: 2021-09-28
Publication date: 2021-12-31

Abstract

The invention discloses a treatment system and a treatment method for rinsing water for producing anhydrous iron phosphate, which solve the technical problems of high cost and low recovery rate in rinsing water treatment in the prior art. A processing system, comprising: the rinsing water pretreatment unit is used for converting most polyvalent metal ions in the rinsing water into precipitates, carrying out solid-liquid separation on a generated solid-liquid mixture and outputting clear rinsing water; the clear rinsing water separation unit is used for removing most of particulate matters and polyvalent metal ions in the clear rinsing water and outputting low-salt rinsing water; the primary membrane concentration unit is used for concentrating the low-salt rinsing water and outputting a primary concentrated solution and a primary permeate; the first membrane concentration unit is used for concentrating the primary concentrated solution and outputting a first concentrated solution and a first permeate; a crystallization unit for crystallizing and separating out ammonium sulfate in the first concentrated solution; and the second membrane concentration unit is used for concentrating the first permeate and outputting the water produced at the terminal. The processing method adopts the processing system.

Description

Treatment system and treatment method for rinsing water for producing anhydrous iron phosphate

Technical Field

The invention relates to the technical field of treatment of wastewater generated in anhydrous iron phosphate production, in particular to a treatment system and a treatment method of rinsing water for producing anhydrous iron phosphate.

Background

One important use of anhydrous iron phosphate is as a positive electrode material for batteries. The production process of the battery-grade anhydrous iron phosphate mainly comprises the following steps: pre-dissolving, synthesizing, filter pressing and washing, high-temperature aging, filter pressing and washing, drying, crushing and packaging. In the process, mother liquor and rinsing water are generated, wherein the mother liquor is mainly generated by rough washing and filter pressing first washing of the synthesis tank, and the rinsing water is mainly generated by filter pressing second washing.

Taking anhydrous iron phosphate production with a yield of 2 ten thousand tons per year as an example, the mother liquor and rinsing water are both acidic and generally contain abundant recoverable resources and water pollutants, for example, the ammonia nitrogen content is about 1500-5000 mg/L, the manganese content is about 70-100 mg/L, the iron content is about 6-30 mg/L, the calcium content is about 5-10 mg/L, the magnesium content is about 50-550 mg/L, and the fluorine content is about 15-30 mg/L; in addition, the mother liquor has a high temperature of about 40-50 ℃, and the rinsing water also contains more phosphorus, and the total phosphorus content is about 100-600 mg/L.

The prior water treatment process and system can not realize low cost, high benefit and zero emission when treating the mother liquor and the rinsing water.

Disclosure of Invention

The invention aims to provide a treatment system and a treatment method for mother liquor for producing anhydrous iron phosphate, which aim to solve the technical problems of high cost and low recovery rate in mother liquor treatment in the prior art.

In order to achieve the above object, a first aspect of the present invention provides a processing system and a processing method for a mother liquor for producing anhydrous iron phosphate. The technical scheme is as follows:

a processing system for producing a mother liquor of anhydrous ferric phosphate, comprising: the mother liquor pretreatment unit is used for converting most of polyvalent metal ions and phosphorus in the mother liquor into precipitates, carrying out solid-liquid separation on a generated solid-liquid mixture and outputting clear mother liquor; the clear mother liquor separation unit is used for removing most of particulate matters and polyvalent metal ions in the clear mother liquor and outputting low-salt mother liquor; the first membrane concentration unit is used for concentrating the low-salt mother liquor and outputting a first concentrated solution and a first permeate; a crystallization unit for crystallizing and separating out ammonium sulfate in the first concentrated solution; and the second membrane concentration unit is used for concentrating the first permeate and outputting the water produced at the terminal.

The treatment method of the mother liquor for producing the anhydrous ferric phosphate adopts the treatment system of the mother liquor.

The second purpose of the invention is to provide a treatment system and a treatment method for rinse water for producing anhydrous ferric phosphate, which are used for solving the technical problems of high cost and low recovery rate of rinse water treatment in the prior art.

In order to achieve the above object, a second aspect of the present invention provides a treatment system and a treatment method for rinse water for producing anhydrous iron phosphate. The technical scheme is as follows:

a treatment system for producing rinse water of anhydrous ferric phosphate, comprising: the rinsing water pretreatment unit is used for converting most polyvalent metal ions in the rinsing water into precipitates, carrying out solid-liquid separation on a generated solid-liquid mixture and outputting clear rinsing water; the clear rinsing water separation unit is used for removing most of particulate matters and polyvalent metal ions in the clear rinsing water and outputting low-salt rinsing water; the primary membrane concentration unit is used for concentrating the low-salt rinsing water and outputting a primary concentrated solution and a primary permeate; the first membrane concentration unit is used for concentrating the primary concentrated solution and outputting a first concentrated solution and a first permeate; a crystallization unit for crystallizing and separating out ammonium sulfate in the first concentrated solution; and the second membrane concentration unit is used for concentrating the first permeate and outputting the water produced at the terminal.

The treatment method of the rinsing water for producing the anhydrous ferric phosphate adopts the treatment system of the rinsing water.

The third purpose of the invention is to provide a treatment system and a treatment method for wastewater generated in the production of anhydrous iron phosphate, so as to solve the technical problems of high cost and low recovery rate in wastewater treatment in the prior art.

In order to achieve the above object, a third aspect of the present invention provides a treatment system and a treatment method for wastewater from the production of anhydrous iron phosphate. The technical scheme is as follows:

a first treatment system for wastewater from the production of anhydrous ferric phosphate, said wastewater comprising a mother liquor and a rinse water, comprising: the mother liquor pretreatment unit is used for converting most of polyvalent metal ions and phosphorus in the mother liquor into precipitates, carrying out solid-liquid separation on a generated solid-liquid mixture and outputting clear mother liquor; the clear mother liquor separation unit is used for removing most of particulate matters and polyvalent metal ions in the clear mother liquor and outputting low-salt mother liquor; the rinsing water pretreatment unit is used for converting most polyvalent metal ions in the rinsing water into precipitates, carrying out solid-liquid separation on a generated solid-liquid mixture and outputting clear rinsing water; the clear rinsing water separation unit is used for removing most of particulate matters and polyvalent metal ions in the clear rinsing water and outputting low-salt rinsing water; the primary membrane concentration unit is used for concentrating the low-salt rinsing water and outputting a primary concentrated solution and a primary permeate; the first membrane concentration unit is used for concentrating the low-salt mother liquor and the primary concentrated solution and outputting a primary concentrated solution and a primary permeate; a crystallization unit for crystallizing and separating out ammonium sulfate in the first concentrated solution; and the second membrane concentration unit is used for concentrating the first permeate and outputting the water produced at the terminal.

A second treatment system for wastewater from the production of anhydrous ferric phosphate, said wastewater comprising a mother liquor and a rinse water, comprising: the mother liquor pretreatment unit is used for converting most of polyvalent metal ions and phosphorus in the mother liquor into precipitates, carrying out solid-liquid separation on a generated solid-liquid mixture and outputting clear mother liquor; the rinsing water pretreatment unit is used for converting most polyvalent metal ions in the rinsing water into precipitates, carrying out solid-liquid separation on a generated solid-liquid mixture and outputting clear rinsing water; the mixing and separating unit is used for removing most of particulate matters and polyvalent metal ions in the clear mother liquor and the clear rinsing water and outputting low-salt liquor; the primary membrane concentration unit is used for concentrating the low-salt solution and outputting a primary concentrated solution and a primary permeate; the first membrane concentration unit is used for concentrating the primary concentrated solution and outputting a primary concentrated solution and a primary permeate; a crystallization unit for crystallizing and separating out ammonium sulfate in the first concentrated solution; and the second membrane concentration unit is used for concentrating the first permeate and outputting the water produced at the terminal.

The treatment method of the wastewater for producing the anhydrous ferric phosphate adopts the treatment system of the wastewater.

The invention is further described with reference to the following figures and detailed description. Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to assist in understanding the invention, and are included to explain the invention and their equivalents and not limit it unduly. In the drawings:

fig. 1 is a schematic structural view of an embodiment of the treatment system for producing a mother liquor of anhydrous iron phosphate according to the present invention.

Fig. 2 is a schematic structural view of an embodiment of the rinse water treatment system for producing anhydrous iron phosphate according to the present invention.

Fig. 3 is a schematic structural view of a first embodiment of the wastewater treatment system for producing anhydrous iron phosphate according to the present invention.

Fig. 4 is a schematic structural view of a second embodiment of the wastewater treatment system for producing anhydrous iron phosphate according to the present invention. The relevant references in the above figures are:

110-mother liquor pretreatment unit, 111-first reaction tank, 112-first filtering device, 113-second reaction tank, 114-second filtering device, 115-heat exchange device, 116-first regulating tank, 120-rinsing water pretreatment unit, 121-primary reaction tank, 122-primary filtering device, 123-second regulating tank, 210-clear mother liquor separation unit, 220-clear rinsing water separation unit, 230-mixed separation unit, 241-rough filtering device, 242-ultrafiltration device, 243-resin adsorption device, 300-acid-alkali liquor treatment unit, 310-acid-alkali reaction tank, 320-terminal filtering device, 400-primary membrane concentration unit, 510-first reverse osmosis device, 520-second reverse osmosis device, 610-third reverse osmosis device, 620-fourth reverse osmosis device, 700-crystallization unit.

Detailed Description

The invention will be described more fully hereinafter with reference to the accompanying drawings. Those skilled in the art will be able to implement the invention based on these teachings. Before the present invention is described in detail with reference to the accompanying drawings, it is to be noted that:

the technical solutions and features provided in the present invention in the respective sections including the following description may be combined with each other without conflict.

Moreover, the embodiments of the present invention described in the following description are generally only some embodiments of the present invention, and not all embodiments. Therefore, all other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without any creative effort shall fall within the protection scope of the present invention.

With respect to terms and units in the present invention. The terms "comprising," "having," and any variations thereof in the description and claims of this invention and the related sections are intended to cover non-exclusive inclusions.

As shown in fig. 1, a processing system of a mother liquor for producing anhydrous iron phosphate includes: the system comprises a mother liquor pretreatment unit 110, a clear mother liquor separation unit 210, an acid-base liquor treatment unit 300, a first membrane concentration unit, a crystallization unit 700 and a second membrane concentration unit.

The mother liquor pretreatment unit 110 is configured to convert most of polyvalent metal ions and phosphorus in the mother liquor into a precipitate, perform solid-liquid separation on the generated solid-liquid mixture, and output a clear mother liquor; therefore, most of polyvalent metal ions and phosphorus are removed through the mother liquor pretreatment unit 110 at the front end of the system, so that the treatment capacity and energy consumption of subsequent units can be remarkably reduced, and the operation cost is reduced. The polyvalent metal ions comprise any of iron ions, magnesium ions, calcium ions, nickel ions and manganese ions. The term "phosphorus" as used herein refers to total phosphorus (commonly referred to as TP) having the meaning: refers to the total amount of inorganic phosphorus and organic phosphorus in various forms in water, and includes inorganic salts and organic phosphates such as orthophosphate, pyrophosphate, metaphosphate, and polymeric phosphate.

One specific embodiment of the mother liquor pretreatment unit 110 is as follows: the mother liquor pretreatment unit 110 comprises a first conditioning tank 116, a heat exchange device 115, a first reaction tank 111, a first filtering device 112, a second reaction tank 113 and a second filtering device 114; in order to maintain the stability of the system operation, the mother liquor is first stored in the first regulating reservoir 116 and then introduced into the heat exchange device 115 at a certain flow rate; the temperature of the mother liquor is generally 40-50 ℃, and in order to improve the operation stability of subsequent units, the heat exchange equipment 115 is adopted to carry out heat exchange on the mother liquor and output the mother liquor with the temperature of 20-30 ℃ to the first reaction tank 111; the first reaction tank 111 is used for making Fe in mother liquor²⁺Conversion of Fe³⁺And allowing the precipitate to settle; the first filtering device 112 is used for filtering the sludge settled in the first reaction tank 111; the second reaction tank 113 is used for converting most of the polyvalent metal ions and phosphorus in the supernatant in the first reaction tank 111 into precipitate; the second filtering device 114 is used for filtering the solid-liquid mixture in the second reaction tank 113, so as to obtain a clear mother liquor.

The heat exchange device 115 adopts one heat exchanger or a plurality of heat exchangers connected in parallel or in series, and the heat exchanger can adopt a gas-liquid heat exchanger or a liquid-liquid heat exchanger.

In the first reaction tank 111, Fe²⁺Conversion of Fe³⁺And the specific manner of settling the precipitate may be, but is not limited to: adjusting the pH to 3-4 by adopting ammonia water, and adding Fe by adopting hydrogen peroxide²⁺Conversion of Fe³⁺Forming ferric hydroxide colloid, and flocculating and settling the ferric hydroxide colloid under the action of flocculating agent PAC and/or PAM; in order to improve the sedimentation effect, the first reaction tank 111 is preferably an inclined tube sedimentation tank.

The first filtering device 112 preferably adopts a plate-and-frame filter pressing device, the filter pressing liquid can flow back to the first regulating tank 116 for circulation, and the interception substance mainly consists of ferric hydroxide colloid, so that the effective recovery of iron resources is realized.

In order to convert as much polyvalent metal ions and phosphorus in the supernatant in the first reaction tank 111 into a precipitate, the second reaction tank 113 specifically comprises a first-stage reaction tank, a second-stage reaction tank and a third-stage reaction tank which are connected in sequence; in a first-stage reaction tank, adjusting the pH to 9-9.5 by adopting ammonia water, and reacting magnesium sulfate with magnesium ions and phosphorus in the supernatant to generate magnesium ammonium phosphate (MAP, also called struvite) by taking magnesium sulfate as a precipitator; in the secondary reaction tank, ammonium carbonate is used as a precipitator, and the ammonium carbonate reacts with multivalent metal ions which are precipitated by carbonates such as magnesium ions and manganese ions; and in the third-stage reaction tank, the generated precipitate is flocculated and settled under the action of flocculating agents PAC and/or PAM, so that the precipitate is filtered by the second filtering equipment 114.

The second filtering device 114 preferably adopts a plate-and-frame filter pressing device, the filter pressing liquid is the clear mother liquid, and the interception is rich in MAP and can be used as medicines and fertilizers.

The clear mother liquor separation unit 210 is used for further removing most of particulate matters and polyvalent metal ions in the clear mother liquor and outputting clear low-salt mother liquor; therefore, most of particles and polyvalent metal ions remained in the clear mother liquor are deeply removed by further adopting the clear mother liquor separation unit 210, so that the stable operation of subsequent units is facilitated, such as reduction of membrane scaling and pollution, avoidance of blockage of crystallization equipment, improvement of product purity and the like.

One specific embodiment of the clean mother liquor separation unit 210 is as follows: the clear mother liquor separation unit 210 includes a rough filtration apparatus 241, an ultrafiltration apparatus 242, and a resin adsorption apparatus 243; the rough filtering device 241 is used for filtering the clear mother liquor; the ultrafiltration equipment 242 is used for performing ultrafiltration membrane separation on the filtrate output by the rough filtration equipment 241; the resin adsorption equipment 243 is used for adsorbing most of polyvalent metal ions in the ultrafiltration product water output by the ultrafiltration equipment 242, and low-salt mother liquor is obtained.

The coarse filtration device 241 firstly removes suspended matters remaining in the clear mother liquor, the ultrafiltration device 242 further intercepts impurities of smaller size in the filtrate to obtain clarified ultrafiltration product water, the clarified ultrafiltration product water can improve the adsorption efficiency and the service life of the subsequent resin adsorption device 243, and the intercepted ultrafiltration concentrated water can flow back to the second reaction tank 113 for circulation. The coarse filtration device 241 preferably adopts a V-shaped filter or a multi-medium filter; the ultrafiltration apparatus 242 preferably employs a hollow fiber ultrafiltration membrane; the resin used in the resin adsorption device 243 is preferably a sodium resin. Therefore, the combination of the coarse filtration device 241, the ultrafiltration device 242 and the resin adsorption device 243 can significantly improve the treatment efficiency.

The ultrafiltration water can be temporarily stored in an ultrafiltration water generating tank and then introduced into the resin adsorption equipment 243 at a certain flow rate; also, the ultrafiltration product water may be returned to the ultrafiltration apparatus 242 at intervals to flush the ultrafiltration membrane to restore membrane flux.

The acid-base solution treatment unit 300 is used for treating the acid-base solution output by the resin adsorption device 243 to recover carbonate in the acid-base solution.

One specific embodiment of the acid and alkali solution treatment unit 300 is as follows: the acid-alkali liquid treatment unit 300 comprises an acid-alkali reaction tank 310 and a terminal filtering device 320; the acid-base reaction tank 310 is used for converting most of the multivalent metal ions in the acid-base solution output by the resin adsorption device 243 into precipitates, and particularly, but not limited to, ammonium bicarbonate is used as a precipitating agent; the terminal filtering device 320 is used for filtering a solid-liquid mixture in the acid-base reaction tank 310, the terminal filtering device 320 preferably adopts a plate-and-frame filter pressing device, the interception substance is carbonate sludge mainly composed of calcium carbonate, magnesium carbonate, manganese carbonate and nickel carbonate, and the filter pressing liquid mainly contains ammonium phosphate and can be recycled.

The first membrane concentration unit is used for concentrating the low-salt mother liquor output by the resin adsorption equipment 243 and outputting a first concentrated solution and a first permeate; through concentration, the treatment capacity of the crystallization unit 700 can be obviously reduced, and the energy consumption is saved.

Reverse osmosis equipment is preferably adopted in the first membrane concentration unit so as to effectively intercept salts in the low-salt mother liquor, so that the salts are enriched to 190-200 g/L and are easier to crystallize and separate out. Further, the first membrane concentration unit preferably comprises at least two stages of reverse osmosis devices, which contribute to the stability and concentration effect of the concentration.

One specific embodiment of the first membrane concentration unit is: the first membrane concentration unit comprises a first reverse osmosis device 510 and a second reverse osmosis device 520; the first reverse osmosis equipment 510 is used for concentrating the low-salt mother liquor and outputting first produced water and first concentrated water, wherein the TDS of the first produced water is less than 200mg/L, and the salt content of the first concentrated water is 130-140 g/L; the second reverse osmosis equipment 520 is used for concentrating the first concentrated water and outputting second produced water and first concentrated solution, wherein the TDS of the second produced water is less than 500mg/L, and the salt content of the first concentrated solution is 190-200 g/L; the first and second produced water constitute a first permeate. "TDS" is an abbreviation for Total dissolved solids, also known as Total dissolved solids, and the unit "mg/L" represents the amount of dissolved solids per liter of water, with higher TDS values indicating more dissolved material in the water.

The operating pressure of the first reverse osmosis device 510 is greater than that of the second reverse osmosis device 520, so that the first reverse osmosis device 510 quickly concentrates the low-salt mother liquor, and the second reverse osmosis device 520 efficiently intercepts salts, thereby ensuring a high salt concentration rate.

The crystallization unit 700 is used for crystallizing and separating out ammonium sulfate in the first concentrated solution; after the step-by-step treatment of the front end unit of the crystallization unit 700, the crystallization unit 700 has a high crystallization speed, and the obtained ammonium sulfate salt has high purity and yield, so that the ammonium sulfate salt is convenient for secondary utilization. The condensed water produced by the crystallization unit 700 may also contain higher ammonia nitrogen and other pollutants, and therefore, the condensed water is preferably conveyed to the second membrane concentration unit for advanced treatment. The crystallized raffinate contains more ammonium phosphate, which can be combined with the press filtrate output by the terminal filtering equipment 320 for ammonium phosphateAnd (5) uniformly recycling. The crystallization unit 700 preferably employs an evaporative crystallization apparatus, which may be, but is not limited to, an MVR evaporator. "Ammonia nitrogen" refers to a compound of nitrogen in the form of ammonia or ammonium ions, i.e., free ammonia (NH) in water₃) And ammonium ion (NH)₄ ⁺) Nitrogen in the form present.

The second membrane concentration unit is used for concentrating the first permeate and the condensed water and outputting terminal produced water; the second membrane concentration unit can deeply intercept salts and pollutants in the first permeate liquid and the condensate water, and ensures that the produced water is discharged up to the standard or can be reused in the production of anhydrous iron phosphate.

The second membrane concentration unit preferably adopts reverse osmosis equipment to effectively intercept salts and pollutants in the first permeate and the condensed water, so that the conductivity of the terminal produced water is less than 10 us/cm. Further, the second membrane concentration unit preferably comprises at least two stages of reverse osmosis devices, which contribute to the stability and concentration effect of the concentration.

One specific embodiment of the second membrane concentration unit is: the second membrane concentration unit comprises a third reverse osmosis device 610 and a fourth reverse osmosis device 620; the third reverse osmosis device 610 is used for concentrating the first permeate and the condensed water and outputting third produced water and third concentrated water, wherein the TDS of the third produced water is less than 20mg/L, and the third concentrated water flows back to the first membrane concentration unit; the fourth reverse osmosis device 620 is used for concentrating the third produced water and outputting terminal produced water and fourth concentrated water, the fourth concentrated water flows back to the third reverse osmosis device 610, and the conductivity of the terminal produced water is less than 10 us/cm.

The operating pressure of the third reverse osmosis apparatus 610 is greater than that of the fourth reverse osmosis apparatus 620, so that the third reverse osmosis apparatus 610 first rapidly concentrates the first permeate and the condensate, and then the fourth reverse osmosis apparatus 620 efficiently intercepts the remaining salts and contaminants, thereby ensuring a high concentration rate.

The embodiment of the treatment method of the mother liquor for producing the anhydrous iron phosphate adopts the treatment system of the mother liquor, and the method has the advantages of good operation stability, low operation cost, high efficiency, classification and recovery of valuable substances in the mother liquor, good economic benefit and realization of zero emission in a real sense.

As shown in fig. 2, the treatment system for rinsing water for producing anhydrous iron phosphate includes: a rinsing water pretreatment unit 120, a clear rinsing water separation unit 220, an acid-base solution treatment unit 300, a primary membrane concentration unit 400, a first membrane concentration unit, a crystallization unit 700, and a second membrane concentration unit.

The rinsing water pretreatment unit 120 is configured to convert most of polyvalent metal ions in the rinsing water into a precipitate, perform solid-liquid separation on a generated solid-liquid mixture, and output clear rinsing water; therefore, most of the polyvalent metal ions are removed through the rinsing water pretreatment unit 120 at the front end of the system, so that the treatment capacity and energy consumption of the subsequent units can be remarkably reduced, and the operation cost can be reduced. The polyvalent metal ions comprise any of iron ions, magnesium ions, calcium ions, nickel ions and manganese ions.

One embodiment of the rinsing water pretreatment unit 120 is: the rinsing water pretreatment unit 120 includes a second conditioning tank 123, a primary reaction tank 121, and a primary filtering device 122; in order to maintain the stability of the system operation, the rinsing water is firstly stored in the second regulating tank 123 and then is introduced into the primary reaction tank 121 at a certain flow rate; the primary reaction tank 121 is used to make Fe in the rinsing water²⁺Conversion of Fe³⁺And settling the precipitate to obtain supernatant as rinsing water; the primary filtering device 122 is used for filtering the sludge settled in the primary reaction tank 121.

In the primary reaction tank 121, Fe²⁺Conversion of Fe³⁺And the specific manner of settling the precipitate may be, but is not limited to: adjusting the pH to 3-4 by adopting ammonia water, and adding Fe by adopting hydrogen peroxide²⁺Conversion of Fe³⁺Forming ferric hydroxide colloid, and flocculating and settling the ferric hydroxide colloid under the action of flocculating agent PAC and/or PAM; in order to enhance the sedimentation effect, the primary reaction tank 121 is preferably an inclined tube sedimentation tank.

The primary filtering equipment 122 preferably adopts plate-and-frame filter pressing equipment, filter pressing liquid can flow back to the second regulating tank 123 for circulation, and interception objects mainly consist of ferric hydroxide colloid, so that effective recovery of iron resources is realized.

The clean rinse water separation unit 220 is used for further removing most of particulate matters and polyvalent metal ions in the clean rinse water and outputting clear low-salt rinse water; therefore, most of particles and polyvalent metal ions remained in the clean rinsing water are deeply removed by further adopting the clean rinsing water separation unit 220, so that the stable operation of subsequent units is facilitated, such as reduction of membrane scaling and pollution, avoidance of blockage of evaporative crystallization equipment, improvement of product purity and the like.

One specific embodiment of the clean rinse water separation unit 220 is: the clean rinse water separation unit 220 includes a rough filtration apparatus 241, an ultrafiltration apparatus 242, and a resin adsorption apparatus 243; the rough filtering device 241 is used for filtering the clear rinsing water; the ultrafiltration equipment 242 is used for performing ultrafiltration membrane separation on the filtrate output by the rough filtration equipment 241; the resin adsorption device 243 is used for adsorbing most polyvalent metal ions in the ultrafiltration product water output by the ultrafiltration device 242, and low-salt rinsing water is obtained.

The coarse filtration device 241 firstly removes the suspended matters remaining in the clear rinsing water, the ultrafiltration device 242 further intercepts the smaller-sized impurities in the filtrate to obtain clarified ultrafiltration product water, the clarified ultrafiltration product water can improve the adsorption efficiency and the service life of the subsequent resin adsorption device 243, and the intercepted ultrafiltration concentrated water can flow back to the primary reaction tank 121 for circulation. The coarse filtration device 241 preferably adopts a V-shaped filter or a multi-medium filter; the ultrafiltration apparatus 242 preferably employs a hollow fiber ultrafiltration membrane; the resin used in the resin adsorption device 243 is preferably a sodium resin. Therefore, the combination of the coarse filtration device 241, the ultrafiltration device 242 and the resin adsorption device 243 can significantly improve the treatment efficiency.

The primary membrane concentration unit 400 is configured to concentrate the low-salt rinse water output by the resin adsorption device 243, and output a primary concentrated solution and a primary permeate; taking the production of anhydrous iron phosphate with a yield of 2 ten thousand tons/year as an example, the yield of the mother liquor is generally 40m³The yield of rinsing water is generally 196m³Since the yield of the rinse water is generally high, the rinse water treatment system further includes a primary membrane concentration unit 400 to concentrate the low-salt rinse water, as compared with the mother liquor treatment system, so that the treatment amount of the subsequent membrane concentration can be significantly reduced.

The primary membrane concentration unit 400 includes reverse osmosis equipment, and relatively large pressure is used for rapid concentration as much as possible under the concentration rate that the salt content of the primary concentrated solution is ensured to be 60-70 g/L and the TDS of the primary permeate is less than 100mg/L, so that rapid concentration efficiency is ensured. The primary permeate also contains some contaminants and salts, and therefore, it is preferred to pass the primary permeate to a second membrane concentration unit for further treatment. The primary membrane concentration unit 400 is mainly used to achieve rapid concentration by a large operating pressure, and therefore, only one stage of reverse osmosis equipment is used, and of course, a plurality of stages of reverse osmosis equipment can be used to improve the concentration effect.

The first membrane concentration unit is used for concentrating the primary concentrated solution and outputting a first concentrated solution and a first permeate; through concentration, the treatment capacity of the crystallization unit 700 can be obviously reduced, and the energy consumption is saved.

The first membrane concentration unit preferably adopts reverse osmosis equipment to effectively intercept salts in the primary concentrated solution, so that the salts are enriched to 190-200 g/L and are easier to crystallize and separate out in the crystallization unit 700. Further, the first membrane concentration unit preferably comprises at least two stages of reverse osmosis devices, which contribute to the stability and concentration effect of the concentration.

One specific embodiment of the first membrane concentration unit is: the first membrane concentration unit comprises a first reverse osmosis device 510 and a second reverse osmosis device 520; the first reverse osmosis equipment 510 is used for concentrating the primary concentrated solution and outputting first produced water and first concentrated water, wherein the TDS of the first produced water is less than 200mg/L, and the salt content of the first concentrated water is 130-140 g/L; the second reverse osmosis equipment 520 is used for concentrating the first concentrated water and outputting second produced water and first concentrated solution, wherein the TDS of the second produced water is less than 500mg/L, and the salt content of the first concentrated solution is 190-200 g/L; the first and second produced water constitute a first permeate.

The operating pressure of the first reverse osmosis apparatus 510 is greater than that of the second reverse osmosis apparatus 520, so that the first reverse osmosis apparatus 510 first rapidly concentrates the primary concentrated solution, and then the second reverse osmosis apparatus 520 efficiently intercepts salts, thereby ensuring a high concentration rate.

The crystallization unit 700 is used for crystallizing and separating out ammonium sulfate in the first concentrated solution; after the step-by-step treatment of the front end unit of the crystallization unit 700, the crystallization unit 700 has a high crystallization speed, and the obtained ammonium sulfate salt has high purity and yield, so that the ammonium sulfate salt is convenient for secondary utilization. The condensed water produced by the crystallization unit 700 may also contain higher ammonia nitrogen and other pollutants, and therefore, the condensed water is preferably conveyed to the second membrane concentration unit for advanced treatment. The crystallized residual liquid contains more ammonium phosphate, and the ammonium phosphate can be combined with the filter pressing liquid output by the terminal filtering equipment 320 to be recycled uniformly. The crystallization unit 700 preferably employs an evaporative crystallization apparatus, which may be, but is not limited to, an MVR evaporator.

The second membrane concentration unit is used for concentrating the first permeate and the condensed water and outputting terminal produced water; the second membrane concentration unit can deeply intercept residual salts and pollutants in the first permeate liquid and the condensate water, and ensures that the produced water is discharged up to the standard or can be reused in the production of anhydrous iron phosphate.

The second membrane concentration unit preferably adopts reverse osmosis equipment to effectively intercept salts and pollutants in the primary permeate and the condensate water, so that the conductivity of the terminal produced water is less than 10 us/cm. Further, the second membrane concentration unit preferably comprises at least two stages of reverse osmosis devices, which contribute to the stability and concentration effect of the concentration.

One specific embodiment of the second membrane concentration unit is: the second membrane concentration unit comprises a third reverse osmosis device 610 and a fourth reverse osmosis device 620; the third reverse osmosis device 610 is configured to concentrate the first permeate and the condensate and output a third produced water and a third concentrated water, wherein the TDS of the third produced water is less than 20mg/L, and the third concentrated water flows back to the primary membrane concentration unit 400; the fourth reverse osmosis device 620 is used for concentrating the third produced water and outputting terminal produced water and fourth concentrated water, the fourth concentrated water flows back to the third reverse osmosis device 610, and the conductivity of the terminal produced water is less than 10 us/cm.

The embodiment of the rinse water treatment method for producing the anhydrous iron phosphate adopts the rinse water treatment system, and the method has the advantages of good operation stability, low operation cost, high efficiency, classification and recovery of valuable substances in the rinse water, good economic benefit and realization of zero emission in the true sense.

As shown in fig. 3, the treatment system for wastewater for producing anhydrous iron phosphate includes a mother liquor pretreatment unit 110, a clear mother liquor separation unit 210, a rinsing water pretreatment unit 120, a clear rinsing water separation unit 220, an acid-base liquor treatment unit 300, a primary membrane concentration unit 400, a first membrane concentration unit, a crystallization unit 700, and a second membrane concentration unit.

After combination, the acid-alkali solution treatment unit 300 simultaneously treats the acid-alkali solutions output by the clear mother liquor separation unit 210 and the clear rinse water separation unit 220; the first membrane concentration unit simultaneously performs concentration treatment on the primary concentrated solution output by the primary membrane concentration unit 400 and the low-salt mother solution output by the clear mother solution separation unit 210. In addition, the structure of each unit may be the structure of the corresponding unit described above.

Fig. 4 is a schematic structural view of a second embodiment of the wastewater treatment system for producing anhydrous iron phosphate according to the present invention.

As shown in fig. 4, the treatment system for wastewater for producing anhydrous iron phosphate includes a mother liquor pretreatment unit 110, a rinse water pretreatment unit 120, a mixing separation unit 230, an acid-base liquor treatment unit 300, a primary membrane concentration unit 400, a first membrane concentration unit, a crystallization unit 700, and a second membrane concentration unit.

After combination, the mixing and separating unit 230 simultaneously processes the clear mother liquor output by the mother liquor pretreatment unit 110 and the clear rinse water output by the rinse water pretreatment unit 120, and the structure of the mixing and separating unit 230 may be the structure of the clear mother liquor separation unit 210 or the clear rinse water separation unit 220; the acid-alkali liquor treatment unit 300 is used for treating the acid-alkali liquor output by the mixing and separating unit 230; the primary membrane concentration unit 400 processes the low-salt solution output from the mixed separation unit 230. In addition, the structure of each unit may be the structure of the corresponding unit described above.

The embodiment of the treatment method of the wastewater for producing the anhydrous iron phosphate is the treatment system of the rinsing water adopting any one of the embodiments, the method has the advantages of good operation stability, low operation cost, high efficiency, classification and recovery of valuable substances in the wastewater, good economic benefit and realization of zero discharge in the true sense.

The two embodiments of the treatment system and the treatment method for the wastewater for producing the anhydrous iron phosphate efficiently combine the mother liquor treatment and the rinsing water treatment, and effectively reduce the equipment investment cost and the labor input.

Between the units of the above embodiments, an intermediate tank for temporarily storing liquid may be provided, helping to make the system operate stably.

The contents of the present invention have been explained above. Those skilled in the art will be able to implement the invention based on these teachings. All other embodiments, which can be derived by a person skilled in the art from the above description without inventive step, shall fall within the scope of protection of the present invention.

Claims

1. The treatment system for producing rinsing water of anhydrous ferric phosphate is characterized in that: the method comprises the following steps:

a rinsing water pretreatment unit (120) for converting most of polyvalent metal ions in the rinsing water into precipitates, performing solid-liquid separation on the generated solid-liquid mixture, and outputting clear rinsing water;

a clear rinse water separation unit (220) for removing most of particulate matter and polyvalent metal ions in the clear rinse water and outputting low-salt rinse water;

a primary membrane concentration unit (400) for concentrating the low-salt rinse water and outputting a primary concentrated solution and a primary permeate;

the first membrane concentration unit is used for concentrating the primary concentrated solution and outputting a first concentrated solution and a first permeate;

a crystallization unit (700) for crystallizing and precipitating an ammonium sulfate salt in the first concentrated solution;

and the second membrane concentration unit is used for concentrating the first permeate and outputting the water produced at the terminal.

2. The treatment system for rinse water for producing anhydrous iron phosphate according to claim 1, characterized in that: the rinse water pretreatment unit (120) includes:

a primary reaction tank (121) for making Fe in the rinsing water²⁺Conversion of Fe³⁺And settling the precipitate to obtain supernatant as rinsing water;

and the primary filtering device (122) is used for filtering the sludge settled in the primary reaction tank (121).

3. The treatment system for rinsing water for producing anhydrous iron phosphate according to claim 2, wherein: the pH value in the primary reaction tank (121) is 3-4, the oxidant is hydrogen peroxide, and the flocculating agent is PAC and/or PAM; the primary reaction tank (121) adopts an inclined tube sedimentation tank; the primary filtering equipment (122) adopts plate-and-frame filter pressing equipment.

4. The treatment system for rinse water for producing anhydrous iron phosphate according to claim 1, characterized in that: the rinse water separation unit (220) comprises:

a coarse filtration device (241) for filtering the clear rinse water;

the ultrafiltration device (242) is used for carrying out membrane separation on the filtrate output by the rough filtration device (241);

and the resin adsorption equipment (243) is used for adsorbing most of polyvalent metal ions in the ultrafiltration product water output by the ultrafiltration equipment (242), namely the low-salt clear rinsing water.

5. The treatment system for rinse water for producing anhydrous iron phosphate according to claim 1, characterized in that: the primary membrane concentration unit (400) comprises reverse osmosis equipment, the salt content of primary concentrated solution is 60-70 g/L, and the TDS of primary permeate is less than 100 mg/L; and/or the crystallization unit (700) adopts an evaporation crystallization device, and the obtained condensed water flows into the second membrane concentration unit.

6. The treatment system for rinse water for producing anhydrous iron phosphate according to claim 1, characterized in that: the first membrane concentration unit comprises at least two stages of reverse osmosis equipment; and/or the salt content of the first concentrated solution is 190-200 g/L.

7. The treatment system for rinse water for producing anhydrous iron phosphate according to claim 6, wherein: the first membrane concentration unit includes:

the first reverse osmosis equipment (510) is used for concentrating the primary concentrated solution and outputting first produced water and first concentrated water, wherein the first produced water forms one part of the first permeate, the TDS of the first produced water is less than 200mg/L, and the salt content of the first concentrated water is 130-140 g/L;

and the second reverse osmosis equipment (520) is used for concentrating the first concentrated water and outputting second produced water and first concentrated solution, wherein the second produced water forms one part of the first permeate, and the TDS of the second produced water is less than 500 mg/L.

8. The treatment system for rinse water for producing anhydrous iron phosphate according to claim 1, characterized in that: the second membrane concentration unit comprises at least two stages of reverse osmosis equipment; and/or the conductivity of the end product water is less than 10 us/cm.

9. The treatment system for rinse water for producing anhydrous iron phosphate according to claim 1, characterized in that: the second membrane concentration unit includes:

a third reverse osmosis device (610) for concentrating the first permeate and outputting a third produced water and a third concentrated water, wherein the TDS of the third produced water is less than 20mg/L, and the third concentrated water flows back to the primary membrane concentration unit (400);

and the fourth reverse osmosis equipment (620) is used for concentrating the third produced water and outputting terminal produced water and fourth concentrated water, and the fourth concentrated water flows back to the third reverse osmosis equipment (610).

10. The treatment method of rinsing water for producing anhydrous ferric phosphate is characterized by comprising the following steps: use of a processing system according to any of claims 1 to 9.