Treatment system for iron phosphate production wastewater

Abstract

The utility model discloses a treatment system for iron phosphate production wastewater, which comprises a recycled phosphoric acid purification and recovery section for treating washing water to obtain recycled phosphoric acid and first clear liquid; the recycled produced water preparation section is used for treating the first clear liquid to obtain impurity concentrated liquid and recycled produced water; the deep purification and discharge section is used for purifying the impurity concentrated liquor and the reaction mother liquor to obtain produced water reaching the standard; wherein the recycled phosphoric acid purifying and recycling section comprises a filtering unit, a recycling unit and a recycling unit, and the filtering unit is used for filtering washing water and then outputting filtrate; the heat exchange unit is used for cooling the filtrate and then outputting cooling liquid; the resin adsorption unit is used for carrying out adsorption treatment on the cooling liquid and then outputting an adsorbed liquid; the ultra-filtration unit is used for carrying out ultra-filtration treatment on the adsorbed liquid and then outputting ultra-filtration clear liquid; and the phosphoric acid concentration unit is used for concentrating the ultrafiltration clear liquid and then outputting recycled phosphoric acid and first clear liquid.

Description

Technical Field

[0001] The utility model relates to the technical field of wastewater treatment, and more specifically, to a treatment system for wastewater produced in the production of iron phosphate. Background Art

[0002] Anhydrous iron phosphate (with the molecular formula FePO4) is an important chemical raw material and is widely used as the cathode material of lithium-ion batteries. The iron method (Fe + H3PO4 → FePO4 + H2) and the iron red method (Fe2O3 + 2H3PO4 → 2FePO4 + 3H2O) are common methods for producing battery-grade anhydrous iron phosphate. The production process of the iron method / iron red method mainly includes the steps of synthesis - solid-liquid separation (usually by pressure filtration) - washing - drying - pulverizing and packaging. In the above production process, reaction mother liquor is generated in the solid-liquid separation section, and washing water is generated in the washing section. The iron phosphate production wastewater composed of washing water and reaction mother liquor contains rich recoverable resources and water pollutants, and needs to be discharged after purification and resource recovery.

[0003] In the prior art, there are mainly three treatment methods for iron phosphate production wastewater. The first is to directly mix the washing water and reaction mother liquor for treatment. The second is to treat the washing water and reaction mother liquor separately. The third is to first perform pretreatment for impurity removal on the washing water and reaction mother liquor respectively, and then mix them for resource recovery treatment. Among them, the second and third methods are usually carried out in parallel and adopt generally the same process.

[0004] First, taking the production of a certain anhydrous iron phosphate as an example, the water volume of the washing water is 40m 3 / h, the TDS is 15.68 g / L, the phosphoric acid concentration is 15.32 g / L, the silicon element concentration is 22.3 mg / L, and the fluoride ion concentration is 10 mg / L. While the water volume of the reaction mother liquor is only 0.5m 3 / h, the TDS is 179.29 g / L, the phosphoric acid concentration is 159.47 g / L, the silicon element concentration is 1113.5 mg / L, and the fluoride ion concentration is 500 mg / L. By comparison, there are huge differences in the water volume and water quality parameter concentrations between the washing water and the reaction mother liquor. Among them, the water volume of the washing water is large, and the contents of silicon element and fluoride ion are less. While the water volume of the reaction mother liquor is small. Although the phosphoric acid content is high, the contents of silicon element and fluoride ion are high. Therefore, the above three treatment methods are not conducive to the efficient recovery of resources and the deep removal of pollutants, and cannot balance low cost, high benefit and zero discharge. Moreover, both the washing water and the reaction mother liquor contain more phosphoric acid. The traditional method uses calcium hydroxide for neutralization precipitation, with high alkali consumption and the generation of a large amount of solid waste.

[0005] Secondly, the target resource recoveries in the current treatment of phosphoric iron production wastewater are usually ammonium sulfate and ammonium phosphate salts obtained by evaporation crystallization at the end. These resources cannot be directly reused in the enterprise itself and are usually sold externally, which increases the sales cost. Although the Chinese Utility Model Patent Application CN114873824A and the Chinese Utility Model Patent CN219991386U disclose technical solutions for phosphoric acid as the target resource recovery, the treatment method still directly mixes the washing water and the reaction mother liquor for treatment, and there are still many impurities in the end liquid after phosphoric acid recovery, which cannot be directly reused or discharged. Utility Model Content

[0006] The technical problem to be solved by the present utility model is to provide a treatment method and a treatment system for phosphoric iron production wastewater that can not only recover phosphoric acid for reuse in the phosphoric iron synthesis section, but also take into account low cost, high efficiency and zero discharge.

[0007] To achieve the above object, the present utility model first provides a treatment method for phosphoric iron production wastewater, and the technical solution is as follows:

[0008] The treatment method for phosphoric iron production wastewater, wherein the phosphoric iron production wastewater includes washing water and reaction mother liquor generated during the production of phosphoric iron by the iron method / iron red method, and includes the following steps:

[0009] (1) Reuse the phosphoric acid purification and recovery process, including:

[0010] Pre-treat the washing water in sequence, and the pre-treatment includes filtration treatment, cooling treatment, resin adsorption treatment and ultrafiltration treatment to obtain an ultrafiltration clear liquid;

[0011] Perform phosphoric acid recovery treatment on the ultrafiltration clear liquid to obtain recycled phosphoric acid and a first clear liquid;

[0012] (2) Reuse the produced water preparation process, including:

[0013] Adjust the pH of the first clear liquid with an alkali solution to obtain raw water;

[0014] Concentrate the first mixture including the raw water and make-up water to obtain a concentrated impurity liquid and recycled produced water;

[0015] (3) Deep purification and discharge process, including:

[0016] Purify the second mixture including the concentrated impurity liquid, the reaction mother liquor and the resin regeneration liquid to obtain qualified produced water.

[0017] As a further improvement of the above treatment method for phosphoric iron production wastewater:

[0018] The TDS of the washing water is ≤ 16500 mg / L, the phosphoric acid concentration is ≤ 16200 mg / L, the sulfate radical concentration is ≤ 150 mg / L, the sodium ion concentration is ≤ 15 mg / L, the total iron ion concentration is ≤ 30 mg / L, the manganese ion concentration is ≤ 30 mg / L, the calcium ion concentration is ≤ 3 mg / L, the magnesium ion concentration is ≤ 0.5 mg / L, the copper ion concentration is ≤ 1 mg / L, the zinc ion concentration is ≤ 0.5 mg / L, the silicon element concentration is ≤ 28 mg / L, and the fluoride ion concentration is ≤ 14 mg / L;

[0019] The TDS of the ultrafiltration permeate is ≤ 16500 g / L, the phosphoric acid concentration is ≤ 16200 mg / L, the sulfate radical concentration is ≤ 150 mg / L, the sodium ion concentration is ≤ 15 mg / L, the total iron ion concentration is ≤ 0.5 mg / L, the manganese ion concentration is ≤ 0.5 mg / L, the calcium ion concentration is ≤ 0.5 mg / L, the magnesium ion concentration is ≤ 0.5 mg / L, the copper ion concentration is ≤ 0.5 mg / L, the zinc ion concentration is ≤ 0.5 mg / L, the silicon element concentration is ≤ 28 mg / L, and the fluoride ion concentration is ≤ 14 mg / L;

[0020] The TDS of the recycled phosphoric acid is ≤ 95000 mg / L, the phosphoric acid concentration is ≤ 94000 mg / L, the sulfate radical concentration is ≤ 610 mg / L, the sodium ion concentration is ≤ 60 mg / L, the total iron ion concentration is ≤ 3 mg / L, the manganese ion concentration is ≤ 3 mg / L, the calcium ion concentration is ≤ 3 mg / L, the magnesium ion concentration is ≤ 3 mg / L, the copper ion concentration is ≤ 3 mg / L, the zinc ion concentration is ≤ 2.5 mg / L, the silicon element concentration is ≤ 140 mg / L, and the fluoride ion concentration is ≤ 20 mg / L.

[0021] As a further improvement of the above method for treating phosphoric acid iron production wastewater: The process of phosphoric acid recovery treatment for the ultrafiltration permeate is as follows:

[0022] The ultrafiltration permeate is subjected to reverse osmosis membrane concentration treatment to obtain a phosphoric acid concentrate with a mass fraction of 8 - 10% and a purity ≥ 96% and the first produced water;

[0023] The phosphoric acid concentrate is subjected to reverse osmosis membrane concentration treatment to obtain a recycled phosphoric acid with a mass fraction of 20 - 85% and the second produced water; wherein, the first produced water and the second produced water constitute the first clear liquid.

[0024] As a further improvement of the above method for treating phosphoric acid iron production wastewater:

[0025] The resin adsorption treatment uses a strong acid cation resin;

[0026] The resin used for resin adsorption treatment is regenerated with a dilute sulfuric acid with a mass fraction of 8 - 10%, and the resin regeneration liquid with a sulfuric acid mass fraction of 6 - 7% obtained enters the second mixture;

[0027] The regenerated resin is rinsed with pure water, and the obtained rinse water is recycled and mixed with the wash water for filtration treatment.

[0028] As a further improvement to the above method for treating phosphoric acid iron production wastewater:

[0029] The makeup water is obtained by successively subjecting tap water to sand filtration and activated carbon adsorption. The TDS of the makeup water is ≤ 250 mg / L, the sulfate ion concentration is ≤ 160 mg / L, the sodium ion concentration is ≤ 12 mg / L, the calcium ion concentration is ≤ 50 mg / L, the magnesium ion concentration is ≤ 9 mg / L, and the silicon element concentration is ≤ 9 mg / L.

[0030] The TDS of the raw water is ≤ 1100 mg / L, the phosphoric acid concentration is ≤ 860 mg / L, the sulfate ion concentration is ≤ 7 mg / L, the sodium ion concentration is ≤ 210 mg / L, the total iron ion concentration is ≤ 0.05 mg / L, the manganese ion concentration is ≤ 0.05 mg / L, the calcium ion concentration is ≤ 0.05 mg / L, the magnesium ion concentration is ≤ 0.05 mg / L, the copper ion concentration is ≤ 0.05 mg / L, the zinc ion concentration is ≤ 0.04 mg / L, the silicon element concentration is ≤ 2.5 mg / L, and the fluoride ion concentration is ≤ 13 mg / L. The pH of the raw water is 6 - 7.

[0031] The TDS of the impurity concentrated solution is ≤ 14200 mg / L, the phosphoric acid concentration is ≤ 9400 mg / L, the sulfate ion concentration is ≤ 1500 mg / L, the sodium ion concentration is ≤ 2400 mg / L, the total iron ion concentration is ≤ 0.5 mg / L, the manganese ion concentration is ≤ 0.5 mg / L, the calcium ion concentration is ≤ 400 mg / L, the magnesium ion concentration is ≤ 75 mg / L, the copper ion concentration is ≤ 0.5 mg / L, the zinc ion concentration is ≤ 0.4 mg / L, the silicon element concentration is ≤ 90 mg / L, and the fluoride ion concentration is ≤ 110 mg / L.

[0032] As a further improvement to the above method for treating phosphoric acid iron production wastewater: It also includes using a part of the impurity concentrated solution to backwash the sand filter tank used for sand filtration treatment and the activated carbon tank used for activated carbon adsorption. The obtained backwash water is mixed with the impurity concentrated solution, the reaction mother liquor, and the resin regeneration liquid to form a second mixture, which then enters the deep purification and discharge process.

[0033] As a further improvement to the above method for treating phosphoric acid iron production wastewater: The process of concentrating the first mixture is as follows:

[0034] The first mixture is subjected to reverse osmosis membrane concentration treatment to obtain first-stage concentrated water and first-stage product water.

[0035] The first-stage concentrated water is subjected to reverse osmosis membrane concentration treatment to obtain impurity concentrated solution and second-stage product water.

[0036] The primary effluent and secondary effluent are subjected to reverse osmosis membrane concentration treatment to obtain secondary concentrated water and recycled effluent; wherein, the secondary concentrated water is refluxed into the first mixture.

[0037] As a further improvement of the above method for treating phosphoric acid iron production wastewater:

[0038] The TDS of the resin regeneration liquid ≤ 100000 mg / L, the sulfate ion concentration ≤ 95000 mg / L, the total iron ion concentration ≤ 2450 mg / L, the manganese ion concentration ≤ 2200 mg / L, the calcium ion concentration ≤ 165 mg / L, the magnesium ion concentration ≤ 30 mg / L, the copper ion concentration ≤ 80 mg / L, the zinc ion concentration ≤ 21 mg / L;

[0039] The TDS of the reaction mother liquor ≤ 188000 mg / L, the phosphoric acid concentration ≤ 168000 mg / L, the sulfate ion concentration ≤ 15900 mg / L, the sodium ion concentration ≤ 1450 mg / L, the total iron ion concentration ≤ 30 mg / L, the manganese ion concentration ≤ 30 mg / L, the calcium ion concentration ≤ 2.8 mg / L, the magnesium ion concentration ≤ 0.5 mg / L, the copper ion concentration ≤ 1 mg / L, the zinc ion concentration ≤ 0.5 mg / L, the silicon element concentration ≤ 1150 mg / L, the fluoride ion concentration ≤ 520 mg / L;

[0040] The TDS of the second mixture ≤ 54000 mg / L, the phosphoric acid concentration ≤ 36000 mg / L, the sulfate ion concentration ≤ 14500 mg / L, the sodium ion concentration ≤ 2000 mg / L, the total iron ion concentration ≤ 330 mg / L, the manganese ion concentration ≤ 300 mg / L, the calcium ion concentration ≤ 330 mg / L, the magnesium ion concentration ≤ 60 mg / L, the copper ion concentration ≤ 12 mg / L, the zinc ion concentration ≤ 4 mg / L, the silicon element concentration ≤ 220 mg / L, the fluoride ion concentration ≤ 150 mg / L.

[0041] As a further improvement of the above method for treating phosphoric acid iron production wastewater: The deep purification and discharge process specifically includes:

[0042] A precipitant is added to the second mixture, and then flocculation sedimentation and solid-liquid separation treatment are carried out to obtain a second clear liquid;

[0043] The pH of the second clear liquid is adjusted to 4 - 5 with an acid solution to obtain a third clear liquid.

[0044] As a further improvement of the above method for treating phosphoric acid iron production wastewater: The deep purification and discharge process further includes:

[0045] The third clear liquid is subjected to Fenton oxidation treatment, and then flocculation sedimentation and solid-liquid separation treatment are carried out to obtain a fourth clear liquid;

[0046] Adjust the pH of the fourth clarified liquid to 6 - 9 with lye to obtain qualified product water.

[0047] To achieve the above object, the present utility model secondly provides three treatment systems for phosphoric acid iron production wastewater, and the technical solutions are as follows:

[0048] The first treatment system for phosphoric acid iron production wastewater includes:

[0049] A recycled phosphoric acid purification and recovery section for treating wash water to obtain recycled phosphoric acid and a first clarified liquid;

[0050] A recycled product water preparation section for treating the first clarified liquid to obtain an impurity concentrated liquid and recycled product water;

[0051] A deep purification and discharge section for purifying the impurity concentrated liquid and reaction mother liquor to obtain qualified product water;

[0052] Among them, the recycled phosphoric acid purification and recovery section includes:

[0053] A filtration unit that filters the wash water and outputs a filtrate;

[0054] A heat exchange unit that cools the filtrate and outputs a coolant;

[0055] A resin adsorption unit that adsorbs the coolant and outputs an adsorbed liquid;

[0056] An ultrafiltration unit that ultrafilters the adsorbed liquid and outputs an ultrafiltration clarified liquid;

[0057] A phosphoric acid concentration unit that concentrates the ultrafiltration clarified liquid and outputs recycled phosphoric acid and a first clarified liquid.

[0058] As a further improvement of the first treatment system for phosphoric acid iron production wastewater described above: the filtration unit includes a precision filter and a first filter press. The precision filter filters the wash water to obtain a filtrate and a filter cake. The filtrate is stored in a filtrate storage tank, and the filter cake is collected by back blowing and the formed slag liquid is stored in a slag liquid storage tank; the first filter press filters the slag liquid and the obtained first filtered liquid flows back to the wash water storage tank.

[0059] As a further improvement of the first treatment system for phosphoric acid iron production wastewater described above: the heat exchange unit includes a plate heat exchanger.

[0060] As a further improvement to the above-mentioned first treatment system for phosphoric iron production wastewater: The resin adsorption unit includes a resin adsorption tower, a resin regeneration mechanism, and a resin rinsing mechanism. A strong acid cation resin is provided in the resin adsorption tower. The resin regeneration mechanism sprays and regenerates the strong acid cation resin with dilute sulfuric acid to obtain the resin regeneration liquid. The resin rinsing mechanism rinses the strong acid cation resin with pure water, and the rinsing liquid obtained is refluxed to the wash water storage tank.

[0061] As a further improvement to the above-mentioned first treatment system for phosphoric iron production wastewater: The resin regeneration mechanism includes a graphite diluter, which processes pure water and concentrated sulfuric acid to obtain dilute sulfuric acid for spray regeneration; The resin rinsing mechanism includes a first pipeline for inputting pure water into the graphite diluter and a second pipeline for inputting pure water into the resin adsorption tower.

[0062] As a further improvement to the above-mentioned first treatment system for phosphoric iron production wastewater: The resin adsorption unit further includes an adsorbed liquid storage tank, a concentrated sulfuric acid storage tank, a dilute sulfuric acid storage tank, a resin regeneration liquid storage tank, a rinsing liquid storage tank, and a pure water storage tank.

[0063] As a further improvement to the above-mentioned first treatment system for phosphoric iron production wastewater: The ultrafiltration unit includes an ultrafiltration device and an ultrafiltration clear liquid storage tank. The ultrafiltration device uses an internal pressure type hollow PES membrane sheet.

[0064] As a further improvement to the above-mentioned first treatment system for phosphoric iron production wastewater: The ultrafiltration concentrated liquid obtained after the ultrafiltration unit filters and processes the adsorbed liquid is refluxed to the wash water storage tank.

[0065] As a further improvement to the above-mentioned first treatment system for phosphoric iron production wastewater: The phosphoric acid concentration unit includes:

[0066] A first reverse osmosis device that concentrates the ultrafiltration clear liquid to obtain a phosphoric acid concentrate and a first product water;

[0067] A second reverse osmosis device that concentrates the phosphoric acid concentrate to obtain recycled phosphoric acid and a second product water; Among them, the first product water and the second product water constitute the first clear liquid.

[0068] As a further improvement to the above-mentioned first treatment system for phosphoric iron production wastewater: The phosphoric acid concentration unit further includes a phosphoric acid concentrate storage tank, a recycled phosphoric acid storage tank, and a first clear liquid storage tank.

[0069] The second treatment system for phosphoric iron production wastewater includes:

[0070] A recycled phosphoric acid purification and recovery section for treating wash water to obtain recycled phosphoric acid and a first clear liquid;

[0071] The recycled water preparation section is used to treat the first supernatant to obtain impurity concentrated liquid and recycled water for reuse.

[0072] The advanced purification and discharge section is used to purify the impurity concentrated liquid and reaction mother liquor to obtain qualified produced water.

[0073] Among them, the recycled water preparation section includes:

[0074] The pH adjustment unit adjusts the pH of the first supernatant and outputs raw water.

[0075] The impurity concentration unit concentrates the first mixture including raw water and makeup water and outputs impurity concentrated liquid and recycled water for reuse.

[0076] The makeup water unit is used to input makeup water into the impurity concentration unit.

[0077] As a further improvement of the above-mentioned second treatment system for phosphoric acid iron production wastewater: The pH adjustment unit includes a pH adjustment tank and a first sodium hydroxide dosing device for dosing sodium hydroxide into the pH adjustment tank.

[0078] As a further improvement of the above-mentioned second treatment system for phosphoric acid iron production wastewater: The impurity concentration unit includes a first mixture storage tank and:

[0079] A first-stage reverse osmosis device that concentrates the first mixture to obtain first-stage concentrated water and first-stage produced water.

[0080] A second-stage reverse osmosis device that concentrates the first-stage concentrated water to obtain impurity concentrated liquid and second-stage produced water.

[0081] A third-stage reverse osmosis device that concentrates the first-stage produced water and second-stage produced water to obtain second-stage concentrated water and recycled water for reuse; among them, the second-stage concentrated water is refluxed to the first mixture storage tank.

[0082] As a further improvement of the above-mentioned second treatment system for phosphoric acid iron production wastewater: The impurity concentration unit further includes a first-stage concentrated water storage tank, a two-stage produced water storage tank, an impurity concentrated liquid storage tank, and a recycled water for reuse storage tank. The first-stage produced water and second-stage produced water are stored in the two-stage produced water storage tank.

[0083] As a further improvement of the above-mentioned second treatment system for phosphoric acid iron production wastewater: The makeup water unit includes a tap water storage tank, a sand filter tank, and an activated carbon tank for treating tap water.

[0084] As a further improvement to the above-mentioned second treatment system for phosphoric iron production wastewater: the recycled water production preparation section further includes a backwashing unit for flushing the sand filter tank and the activated carbon tank.

[0085] As a further improvement to the above-mentioned second treatment system for phosphoric iron production wastewater: the backwashing unit includes a third pipeline connecting the impurity concentrated liquid storage tank and the sand filter tank, a fourth pipeline connecting the impurity concentrated liquid storage tank and the activated carbon tank, and a backwashing water storage tank for storing the backwashing water formed by flushing.

[0086] As a further improvement to the above-mentioned second treatment system for phosphoric iron production wastewater:

[0087] The recycled phosphoric acid purification and recovery section includes:

[0088] A filtration unit that filters the washing water and outputs the filtrate;

[0089] A heat exchange unit that cools the filtrate and outputs the coolant;

[0090] A resin adsorption unit that adsorbs the coolant and outputs the post-adsorption liquid;

[0091] An ultrafiltration unit that ultrafilters the post-adsorption liquid and outputs the ultrafiltration clear liquid;

[0092] A phosphoric acid concentration unit that concentrates the ultrafiltration clear liquid and outputs the recycled phosphoric acid and the first clear liquid.

[0093] The deep purification and discharge section includes a homogenization unit that is used to mix the impurity concentrated liquid, the reaction mother liquor, the resin regeneration liquid, and the backwashing water into a second mixture.

[0094] The third treatment system for phosphoric iron production wastewater includes:

[0095] A recycled phosphoric acid purification and recovery section for treating the washing water to obtain recycled phosphoric acid and the first clear liquid;

[0096] A recycled water production preparation section for treating the first clear liquid to obtain the impurity concentrated liquid and the recycled water;

[0097] A deep purification and discharge section for purifying the impurity concentrated liquid and the reaction mother liquor to obtain the qualified produced water;

[0098] Among them, the recycled phosphoric acid purification and recovery section includes:

[0099] A filtration unit that filters the washing water and outputs the filtrate;

[0100] A heat exchange unit that cools the filtrate and outputs coolant.

[0101] A resin adsorption unit that adsorbs the coolant and outputs the post-adsorption liquid.

[0102] An ultrafiltration unit that ultrafilters the post-adsorption liquid and outputs ultrafiltration filtrate.

[0103] A phosphoric acid concentration unit that concentrates the ultrafiltration filtrate and outputs recycled phosphoric acid and first clarified liquid.

[0104] The recycled water preparation section includes:

[0105] A pH adjustment unit that adjusts the pH of the first clarified liquid and outputs raw water.

[0106] An impurity concentration unit that concentrates a first mixture including raw water and makeup water and outputs impurity concentrated liquid and recycled water.

[0107] A makeup water unit that inputs makeup water into the impurity concentration unit.

[0108] The advanced purification and discharge section includes:

[0109] A homogenization unit that mixes the impurity concentrated liquid, reaction mother liquor, and resin regeneration liquid to obtain a second mixture.

[0110] A softening unit that removes impurity ions from the second mixture and outputs second clarified liquid.

[0111] An organic matter degradation unit that removes organic matter from the second clarified liquid and outputs qualified product water.

[0112] As a further improvement of the above-mentioned third phosphoric acid iron production wastewater treatment system: The resin adsorption unit includes a resin adsorption tower, a resin regeneration mechanism, and a resin rinsing mechanism. Strong acid cation resin is provided in the resin adsorption tower. The resin regeneration mechanism sprays and regenerates the strong acid cation resin with dilute sulfuric acid to obtain the resin regeneration liquid. The resin rinsing mechanism rinses the strong acid cation resin with pure water, and the rinsing liquid obtained is returned to the washing water storage tank.

[0113] As a further improvement of the above-mentioned third phosphoric acid iron production wastewater treatment system: The phosphoric acid concentration unit includes:

[0114] A first reverse osmosis device that concentrates the ultrafiltration filtrate to obtain phosphoric acid concentrated liquid and first product water.

[0115] A second reverse osmosis device, which concentrates the phosphoric acid concentrate to obtain recycled phosphoric acid and second produced water; wherein, the first produced water and the second produced water constitute the first clear liquid.

[0116] As a further improvement of the above-mentioned third treatment system for phosphoric acid iron production wastewater: The impurity concentration unit includes a first mixture storage tank and:

[0117] A first-stage reverse osmosis device, which concentrates the first mixture to obtain first-stage concentrated water and first-stage produced water;

[0118] A second-stage reverse osmosis device, which concentrates the first-stage concentrated water to obtain impurity concentrated water and second-stage produced water;

[0119] A third-stage reverse osmosis device, which concentrates the first-stage produced water and the second-stage produced water to obtain second-stage concentrated water and recycled produced water; wherein, the second-stage concentrated water is refluxed to the first mixture storage tank.

[0120] As a further improvement of the above-mentioned third treatment system for phosphoric acid iron production wastewater: The water replenishment unit includes a tap water storage tank, a sand filter tank and an activated carbon tank for treating tap water;

[0121] The recycled produced water preparation section further includes a backwashing unit for flushing the sand filter tank and the activated carbon tank; The backwashing unit includes a third pipeline connecting the impurity concentrated liquid storage tank and the sand filter tank, a fourth pipeline connecting the impurity concentrated liquid storage tank and the activated carbon tank, and a backwashing water storage tank for storing the backwashing water formed by flushing.

[0122] As a further improvement of the above-mentioned third treatment system for phosphoric acid iron production wastewater: The homogenization unit includes a homogenization tank, and the impurity concentrated liquid, the reaction mother liquid, the resin regeneration liquid and the backwashing water are mixed in the homogenization tank to form a second mixture.

[0123] As a further improvement of the above-mentioned third treatment system for phosphoric acid iron production wastewater: The softening unit includes a chemical reaction tank, a flocculation tank, a sludge tank, a second filter press, a precipitant dosing device for adding a precipitant to the chemical reaction tank, and a first flocculant dosing device for adding a flocculant to the flocculation tank, which are connected in sequence.

[0124] As a further improvement of the above-mentioned third treatment system for phosphoric acid iron production wastewater: The precipitant dosing device includes a second sodium hydroxide dosing device and a calcium hydroxide dosing device, and the calcium hydroxide dosing device includes a bin for storing quicklime or slaked lime and a pulping tank for making calcium hydroxide slurry.

[0125] As a further improvement to the above-mentioned third treatment system for phosphoric iron production wastewater: the organic matter degradation unit includes a pH adjustment tank, a Fenton reaction tank, a sedimentation tank, a pH callback tank connected in sequence, and an acid liquid dosing device for dosing acid liquid into the pH adjustment tank, a ferrous sulfate dosing device for dosing ferrous sulfate into the Fenton reaction tank, a hydrogen peroxide dosing device for dosing hydrogen peroxide into the Fenton reaction tank, a second flocculant dosing device for dosing flocculant into the sedimentation tank, and a third sodium hydroxide dosing device for dosing sodium hydroxide into the pH callback tank.

[0126] As a further improvement to the above-mentioned third treatment system for phosphoric iron production wastewater: the sedimentation tank is an inclined plate sedimentation tank, and the sludge deposited in the inclined plate sedimentation tank flows into the second filter press.

[0127] The treatment method and treatment system for phosphoric iron production wastewater of the present utility model have the following advantages:

[0128] (1) The present utility model fully considers the differences in water volume and water quality parameters between washing water and reaction mother liquor. First, taking the washing water with a large water volume and fewer impurities as the object of action, the phosphoric acid and produced water in the washing water are recovered first, and then the residual liquid (i.e., impurity concentrated liquid) is mixed with the reaction mother liquor for deep purification, significantly improving the treatment efficiency and reducing the treatment cost.

[0129] (2) The target resource recovery products of the present utility model are phosphoric acid and produced water, which can be directly reused in the phosphoric iron synthesis section without external sales, saving raw material costs and sales costs.

[0130] (3) The process and structure of the present utility model are simple, the equipment investment cost is low, the energy consumption is low, realizing the resource reuse and up-to-standard discharge of wastewater, taking into account low cost, high benefit and zero discharge, and having extremely strong practicability.

[0131] The following further describes the embodiments of the utility model provided in this specification in conjunction with the drawings and specific implementation manners. The additional aspects and advantages of the embodiments of the utility model provided in this specification will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the embodiments of the utility model provided in this specification. Description of the Drawings

[0132] The drawings constituting a part of the embodiments of the utility model provided in this specification are used to assist in understanding the embodiments of the utility model provided in this specification. The content provided in the drawings and the related descriptions in the embodiments of the utility model provided in this specification can be used to explain the embodiments of the utility model provided in this specification, but do not constitute an improper limitation to the embodiments of the utility model provided in this specification.

[0133] Figure 1This is a schematic structural diagram of the specific implementation mode of the treatment system for phosphoric iron production wastewater of the present utility model.

[0134] Figure 2 This is a water quality change diagram of each treatment unit in the phosphoric acid purification and recovery process in the specific implementation mode of the treatment method for phosphoric iron production wastewater of the present utility model.

[0135] Figure 3 This is a water quality change diagram of each treatment unit in the recycled water production process in the specific implementation mode of the treatment method for phosphoric iron production wastewater of the present utility model.

[0136] Figure 4 This is a water quality change diagram of each treatment unit in the deep purification and discharge process in the specific implementation mode of the treatment method for phosphoric iron production wastewater of the present utility model.

[0137] The relevant markings in the above-mentioned drawings are as follows:

[0138] 100 - washing water storage tank, 111 - precision filter, 112 - first filter press, 113 - filtrate storage tank, 114 - residue liquid storage tank, 120 - plate heat exchanger, 131 - resin adsorption tower, 132 - graphite diluter, 1331 - first pipeline, 1332 - second pipeline, 134 - post-adsorption liquid storage tank, 135 - dilute sulfuric acid storage tank, 136 - resin regeneration liquid storage tank, 137 - eluent storage tank, 138 - pure water storage tank, 141 - ultrafiltration equipment, 142 - ultrafiltration filtrate storage tank, 151 - first reverse osmosis equipment, 152 - second reverse osmosis equipment, 153 - concentrated phosphoric acid storage tank, 154 - recycled phosphoric acid storage tank, 155 - first clear liquid storage tank, 210 - pH adjustment tank, 221 - first mixture storage tank, 222 - first-stage reverse osmosis equipment, 223 - second-stage reverse osmosis equipment, 224 - third-stage reverse osmosis equipment, 225 - first-stage concentrated water storage tank, 226 - two-stage produced water storage tank, 227 - impurity concentrated liquid storage tank, 228 - recycled produced water storage tank, 231 - sand filter tank, 232 - activated carbon tank, 233 - backwashing water storage tank, 234 - third pipeline, 235 - fourth pipeline, 310 - reaction mother liquid storage tank, 320 - homogenization tank, 331 - chemical reaction tank, 332 - flocculation tank, 333 - sludge tank, 334 - second filter press, 335 - bunker, 336 - pulping tank, 341 - pH adjustment pool, 342 - Fenton reaction pool, 343 - inclined plate sedimentation tank, 344 - pH callback pool. Specific implementation mode

[0139] The following clearly and completely describes the embodiments of the utility model provided in this specification in conjunction with the accompanying drawings. Those of ordinary skill in the art will be able to implement the embodiments of the utility model provided in this specification based on these descriptions. Before describing the embodiments of the utility model provided in this specification in conjunction with the accompanying drawings, it should be particularly noted that:

[0140] In the embodiments of the utility model provided in this specification, the technical solutions and technical features provided in each part including the following descriptions can be combined with each other without conflict.

[0141] In addition, the embodiments of the utility model provided in this specification mentioned in the following description are usually only a partial embodiment rather than all embodiments of the embodiments of the utility model provided in this specification. Therefore, based on the embodiments of the utility model provided in this specification, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the scope of protection of the embodiments of the utility model provided in this specification.

[0142] Regarding the terms and units in the embodiments of the utility model provided in this specification: The terms "including", "comprising", "having" and any variations thereof in the description and claims of the embodiments of the utility model provided in this specification and related parts are intended to cover non-exclusive inclusion. In addition, other relevant terms and units in the embodiments of the utility model provided in this specification can be reasonably explained based on the relevant content of the embodiments of the utility model provided in this specification.

[0143] The specific implementation manner of the method for treating phosphoric acid iron production wastewater of the present utility model includes the following steps:

[0144] (1) Recycling the phosphoric acid purification and recovery process, including: sequentially pre-treating the washing water, the pre-treatment including filtration treatment, cooling treatment, resin adsorption treatment and ultrafiltration treatment to obtain an ultrafiltration clear liquid; performing phosphoric acid recovery treatment on the ultrafiltration clear liquid to obtain recycled phosphoric acid and a first clear liquid; specifically as follows:

[0145] Step110, performing filtration treatment on the washing water to remove larger particulate matters and suspended matters to obtain a filtrate with SS≤2mg / L;

[0146] Step120, performing cooling treatment on the filtrate to adapt to the treatment effect of subsequent processes to obtain a coolant with a temperature after cooling treatment≤35°C;

[0147] Step130, performing resin adsorption treatment on the coolant to remove metals such as iron, manganese, and copper to obtain an adsorbed liquid;

[0148] Step 140, perform ultrafiltration treatment on the adsorbed liquid to remove larger particulate matters and suspended solids, obtaining an ultrafiltration filtrate; wherein, the resin adsorption treatment uses strong acid cation resin; the resin used for the resin adsorption treatment is regenerated with dilute sulfuric acid having a mass fraction of 8-10%, and the resin regeneration liquid with a sulfuric acid mass fraction of 6-7% obtained enters the second mixture; the regenerated resin is rinsed with pure water, and the rinsing water obtained is refluxed to be mixed with the washing water and then subjected to filtration treatment;

[0149] Step 150, perform reverse osmosis membrane concentration treatment on the ultrafiltration filtrate, obtaining a phosphoric acid concentrated liquid with a mass fraction of 8-10% and a purity ≥ 96% and the first produced water;

[0150] Step 160, perform reverse osmosis membrane concentration treatment on the phosphoric acid concentrated liquid, obtaining a recycled phosphoric acid with a mass fraction of 20-85% and the second produced water; wherein, the first produced water and the second produced water constitute the first clear liquid.

[0151] Wherein, the TDS of the washing water ≤ 16500 mg / L, the phosphoric acid concentration ≤ 16200 mg / L, the sulfate ion concentration ≤ 150 mg / L, the sodium ion concentration ≤ 15 mg / L, the total iron ion concentration ≤ 30 mg / L, the manganese ion concentration ≤ 30 mg / L, the calcium ion concentration ≤ 3 mg / L, the magnesium ion concentration ≤ 0.5 mg / L, the copper ion concentration ≤ 1 mg / L, the zinc ion concentration ≤ 0.5 mg / L, the silicon element concentration ≤ 28 mg / L, the fluoride ion concentration ≤ 14 mg / L; the temperature of the washing water is 60 °C, and SS ≤ 50 mg / L.

[0152] The TDS of the ultrafiltration filtrate ≤ 16500 g / L, the phosphoric acid concentration ≤ 16200 mg / L, the sulfate ion concentration ≤ 150 mg / L, the sodium ion concentration ≤ 15 mg / L, the total iron ion concentration ≤ 0.5 mg / L, the manganese ion concentration ≤ 0.5 mg / L, the calcium ion concentration ≤ 0.5 mg / L, the magnesium ion concentration ≤ 0.5 mg / L, the copper ion concentration ≤ 0.5 mg / L, the zinc ion concentration ≤ 0.5 mg / L, the silicon element concentration ≤ 28 mg / L, the fluoride ion concentration ≤ 14 mg / L.

[0153] The TDS of the recycled phosphoric acid ≤ 95000 mg / L, the phosphoric acid concentration ≤ 94000 mg / L, the sulfate ion concentration ≤ 610 mg / L, the sodium ion concentration ≤ 60 mg / L, the total iron ion concentration ≤ 3 mg / L, the manganese ion concentration ≤ 3 mg / L, the calcium ion concentration ≤ 3 mg / L, the magnesium ion concentration ≤ 3 mg / L, the copper ion concentration ≤ 3 mg / L, the zinc ion concentration ≤ 2.5 mg / L, the silicon element concentration ≤ 140 mg / L, the fluoride ion concentration ≤ 20 mg / L.

[0154] (2) Reclaimed water production process, including: adjusting the pH of the first supernatant with an alkali solution to obtain raw water; concentrating a first mixture including the raw water and makeup water to obtain a concentrated impurity solution and reclaimed water; specifically as follows:

[0155] Step210, adjusting the pH of the first supernatant with a sodium hydroxide solution with a mass fraction of 32% to obtain raw water with a pH of 6-7;

[0156] Step220, performing reverse osmosis membrane concentration treatment on the first mixture to obtain first-stage concentrated water and first-stage produced water;

[0157] Step230, performing reverse osmosis membrane concentration treatment on the first-stage concentrated water to obtain a concentrated impurity solution and second-stage produced water;

[0158] Step240, performing reverse osmosis membrane concentration treatment on the first-stage produced water and the second-stage produced water to obtain second-stage concentrated water and reclaimed water; wherein, the second-stage concentrated water is refluxed to the first mixture;

[0159] Step250, using a part of the concentrated impurity solution to backwash the sand filter tank for sand filtration treatment and the activated carbon tank for activated carbon adsorption to obtain backwash water.

[0160] Wherein, the makeup water is obtained by sequentially performing sand filtration treatment and activated carbon adsorption on tap water, and the TDS of the makeup water ≤ 250mg / L, the sulfate ion concentration ≤ 160mg / L, the sodium ion concentration ≤ 12mg / L, the calcium ion concentration ≤ 50mg / L, the magnesium ion concentration ≤ 9mg / L, and the silicon element concentration ≤ 9mg / L.

[0161] The TDS of the raw water ≤ 1100mg / L, the phosphoric acid concentration ≤ 860mg / L, the sulfate ion concentration ≤ 7mg / L, the sodium ion concentration ≤ 210mg / L, the total iron ion concentration ≤ 0.05mg / L, the manganese ion concentration ≤ 0.05mg / L, the calcium ion concentration ≤ 0.05mg / L, the magnesium ion concentration ≤ 0.05mg / L, the copper ion concentration ≤ 0.05mg / L, the zinc ion concentration ≤ 0.04mg / L, the silicon element concentration ≤ 2.5mg / L, and the fluoride ion concentration ≤ 13mg / L.

[0162] The TDS of the concentrated impurity solution ≤ 14200mg / L, the phosphoric acid concentration ≤ 9400mg / L, the sulfate ion concentration ≤ 1500mg / L, the sodium ion concentration ≤ 2400mg / L, the total iron ion concentration ≤ 0.5mg / L, the manganese ion concentration ≤ 0.5mg / L, the calcium ion concentration ≤ 400mg / L, the magnesium ion concentration ≤ 75mg / L, the copper ion concentration ≤ 0.5mg / L, the zinc ion concentration ≤ 0.4mg / L, the silicon element concentration ≤ 90mg / L, and the fluoride ion concentration ≤ 110mg / L.

[0163] (3) Deep purification and discharge process, including: purifying the second mixture including impurity concentrated solution, reaction mother liquor, and resin regeneration liquid to obtain qualified product water; specifically as follows:

[0164] Step310, add sodium hydroxide solution with a mass fraction of 32% and calcium hydroxide solution with a mass fraction of 15% (precipitant) to the second mixture, then perform flocculation sedimentation and solid-liquid separation treatment to obtain a second clear liquid;

[0165] Step320, adjust the pH of the second clear liquid to 4 - 5 with sulfuric acid with a mass fraction of 30% to obtain a third clear liquid;

[0166] Step330, perform Fenton oxidation treatment on the third clear liquid with ferrous sulfate solution with a mass fraction of 30% and hydrogen peroxide solution with a mass fraction of 30%, then perform flocculation sedimentation and solid-liquid separation treatment to obtain a fourth clear liquid;

[0167] Step340, adjust the pH of the fourth clear liquid to 6 - 9 with alkali solution to obtain qualified product water.

[0168] Among them, the TDS of the resin regeneration liquid ≤ 100000 mg / L, the sulfate ion concentration ≤ 95000 mg / L, the total iron ion concentration ≤ 2450 mg / L, the manganese ion concentration ≤ 2200 mg / L, the calcium ion concentration ≤ 165 mg / L, the magnesium ion concentration ≤ 30 mg / L, the copper ion concentration ≤ 80 mg / L, the zinc ion concentration ≤ 21 mg / L.

[0169] The TDS of the reaction mother liquor ≤ 188000 mg / L, the phosphoric acid concentration ≤ 168000 mg / L, the sulfate ion concentration ≤ 15900 mg / L, the sodium ion concentration ≤ 1450 mg / L, the total iron ion concentration ≤ 30 mg / L, the manganese ion concentration ≤ 30 mg / L, the calcium ion concentration ≤ 2.8 mg / L, the magnesium ion concentration ≤ 0.5 mg / L, the copper ion concentration ≤ 1 mg / L, the zinc ion concentration ≤ 0.5 mg / L, the silicon element concentration ≤ 1150 mg / L, the fluoride ion concentration ≤ 520 mg / L.

[0170] The TDS of the second mixture ≤ 54000 mg / L, the phosphoric acid concentration ≤ 36000 mg / L, the sulfate ion concentration ≤ 14500 mg / L, the sodium ion concentration ≤ 2000 mg / L, the total iron ion concentration ≤ 330 mg / L, the manganese ion concentration ≤ 300 mg / L, the calcium ion concentration ≤ 330 mg / L, the magnesium ion concentration ≤ 60 mg / L, the copper ion concentration ≤ 12 mg / L, the zinc ion concentration ≤ 4 mg / L, the silicon element concentration ≤ 220 mg / L, the fluoride ion concentration ≤ 150 mg / L.

[0171] The flocculants used for flocculation sedimentation are PAM and / or PAC. Total iron ion refers to Fe3+ and Fe 2+ 。

[0172] Among them, the third supernatant has reached the third-level discharge standard of the Comprehensive Wastewater Discharge Standard (GB 8978-1996). No pollutants are detected in the obtained qualified product water, achieving zero discharge, and it can also be directly discharged or reused in the water-required sections of the system.

[0173] In order to implement the above-mentioned treatment method for phosphoric acid iron production wastewater, the specific implementation manner of the treatment system for phosphoric acid iron production wastewater adopted by the present utility model is as follows.

[0174] Figure 1 It is a structural schematic diagram of the specific implementation manner of the treatment system for phosphoric acid iron production wastewater of the present utility model.

[0175] As Figure 1 shown, the treatment system for phosphoric acid iron production wastewater includes a recycled phosphoric acid purification and recovery section, a recycled product water preparation section, and a deep purification and discharge section.

[0176] The recycled phosphoric acid purification and recovery section is used to treat wash water to obtain recycled phosphoric acid and the first supernatant. The recycled phosphoric acid purification and recovery section includes a filtration unit, a heat exchange unit, a resin adsorption unit, an ultrafiltration unit, and a phosphoric acid concentration unit.

[0177] The filtration unit filters the wash water and outputs filtrate. The filtration unit includes a precision filter 111 and a first filter press 112. The precision filter 111 filters the wash water to obtain filtrate and filter cake. The filtrate is stored in a filtrate storage tank 113, and the slag liquid formed by collecting the filter cake through back blowing is stored in a slag liquid storage tank 114. The first filtrate obtained by the first filter press 112 filtering the slag liquid is refluxed to a wash water storage tank 100.

[0178] The heat exchange unit cools the filtrate and outputs coolant. The heat exchange unit includes a plate heat exchanger 120.

[0179] The resin adsorption unit outputs the post-adsorption liquid after adsorbing and treating the coolant. The resin adsorption unit includes a resin adsorption tower 131, a resin regeneration mechanism, and a resin rinsing mechanism. Strong acid cation resin is provided in the resin adsorption tower 131. The resin regeneration mechanism obtains the resin regeneration liquid by spraying and regenerating the strong acid cation resin with dilute sulfuric acid. The resin regeneration mechanism includes a graphite diluter 132, and the graphite diluter 132 processes pure water and concentrated sulfuric acid to obtain dilute sulfuric acid for spraying and regeneration. The resin rinsing mechanism returns the rinsing liquid obtained by rinsing the strong acid cation resin with pure water to the wash water storage tank 100. The resin rinsing mechanism includes a first pipeline 1331 for inputting pure water into the graphite diluter 132 and a second pipeline 1332 for inputting pure water into the resin adsorption tower 131. The resin adsorption unit further includes a post-adsorption liquid storage tank 134, a concentrated sulfuric acid storage tank, a dilute sulfuric acid storage tank 135, a resin regeneration liquid storage tank 136, a rinsing liquid storage tank 137, and a pure water storage tank 138.

[0180] The ultrafiltration unit outputs the ultrafiltration filtrate after ultrafiltering the post-adsorption liquid. The ultrafiltration unit includes an ultrafiltration device 141 and an ultrafiltration filtrate storage tank 142. The ultrafiltration device 141 uses an internal pressure type hollow PES membrane sheet. The ultrafiltration concentrate obtained by filtering the post-adsorption liquid by the ultrafiltration unit is returned to the wash water storage tank 100.

[0181] The phosphoric acid concentration unit outputs recycled phosphoric acid and a first clear liquid after concentrating the ultrafiltration filtrate. The phosphoric acid concentration unit includes a first reverse osmosis device 151 and a second reverse osmosis device 152. The first reverse osmosis device 151 concentrates the ultrafiltration filtrate to obtain a phosphoric acid concentrate and a first produced water; the second reverse osmosis device 152 concentrates the phosphoric acid concentrate to obtain recycled phosphoric acid and a second produced water; wherein, the first produced water and the second produced water constitute the first clear liquid. The phosphoric acid concentration unit further includes a phosphoric acid concentrate storage tank 153, a recycled phosphoric acid storage tank 154, and a first clear liquid storage tank 155.

[0182] The recycled water preparation section is used for treating the first clear liquid to obtain an impurity concentrate and recycled water. The recycled water preparation section includes a pH adjustment unit, an impurity concentration unit, a water replenishment unit, and a backwashing unit.

[0183] The pH adjustment unit adjusts the pH of the first clear liquid and outputs raw water. The pH adjustment unit includes a pH adjustment tank 210 and a first sodium hydroxide dosing device for dosing sodium hydroxide into the pH adjustment tank 210.

[0184] The impurity concentration unit concentrates the first mixture including raw water and make-up water and outputs concentrated impurity liquid and recycled product water. The impurity concentration unit includes a first mixture storage tank 221, a first-stage reverse osmosis device 222, a second-stage reverse osmosis device 223, and a third-stage reverse osmosis device 224. The first-stage reverse osmosis device 222 concentrates the first mixture to obtain first-stage concentrated water and first-stage product water; the second-stage reverse osmosis device 223 concentrates the first-stage concentrated water to obtain concentrated impurity liquid and second-stage product water; the third-stage reverse osmosis device 224 concentrates the first-stage product water and the second-stage product water to obtain second-stage concentrated water and recycled product water; wherein, the second-stage concentrated water is returned to the first mixture storage tank 221. The impurity concentration unit further includes a first-stage concentrated water storage tank 225, a two-stage product water storage tank 226, a concentrated impurity liquid storage tank 227, and a recycled product water storage tank 228. The first-stage product water and the second-stage product water are stored in the two-stage product water storage tank 226.

[0185] The make-up water unit is used to input make-up water into the impurity concentration unit. The make-up water unit includes a tap water storage tank, a sand filter tank 231 for treating tap water, and an activated carbon tank 232.

[0186] The backwashing unit is used to wash the sand filter tank 231 and the activated carbon tank 232. The backwashing unit includes a third pipeline 234 connecting the concentrated impurity liquid storage tank 227 and the sand filter tank 231, a fourth pipeline 235 connecting the concentrated impurity liquid storage tank 227 and the activated carbon tank 232, and a backwashing water storage tank 233100 for storing the backwashing water formed by washing.

[0187] The advanced purification and discharge section is used to purify the second mixture including concentrated impurity liquid, reaction mother liquor (from the reaction mother liquor storage tank 310), resin regeneration liquid, and backwashing water to obtain qualified product water. The advanced purification and discharge section includes a homogenization unit, a softening unit, and an organic matter degradation unit.

[0188] The homogenization unit is used to mix the concentrated impurity liquid, reaction mother liquor, and resin regeneration liquid to obtain a second mixture. The homogenization unit includes a homogenization tank 320, and the concentrated impurity liquid, reaction mother liquor, resin regeneration liquid, and backwashing water are mixed in the homogenization tank 320 to form a second mixture.

[0189] The softening unit is used to remove impurity ions in the second mixture and output a second clarified liquid. The softening unit includes a chemical reaction tank 331, a flocculation tank 332, a sludge tank 333, a second filter press 334, which are connected in sequence, a precipitant dosing device for dosing a precipitant into the chemical reaction tank 331, and a first flocculant dosing device for dosing a flocculant into the flocculation tank 332. The precipitant dosing device includes a second sodium hydroxide dosing device and a calcium hydroxide dosing device. The calcium hydroxide dosing device includes a bin 335 for storing quicklime or slaked lime and a pulping tank 336 for making calcium hydroxide slurry.

[0190] The organic matter degradation unit is used to remove the organic matter in the second supernatant and output qualified product water. The organic matter degradation unit includes a pH adjustment tank 341, a Fenton reaction tank 342, a sedimentation tank, a pH callback tank 344 connected in sequence, an acid addition device for adding acid solution to the pH adjustment tank 341, a ferrous sulfate addition device for adding ferrous sulfate to the Fenton reaction tank 342, a hydrogen peroxide addition device for adding hydrogen peroxide to the Fenton reaction tank 342, a second flocculant addition device for adding flocculant to the sedimentation tank, and a third sodium hydroxide addition device for adding sodium hydroxide to the pH callback tank 344. The sedimentation tank is an inclined plate sedimentation tank 343, and the sludge deposited in the inclined plate sedimentation tank 343 flows into the second filter press 334.

[0191] The beneficial effects of the present invention are illustrated by the following specific application examples.

[0192] First, in the process of recycling and purifying phosphoric acid, the Figure 1 recycling and purifying section of phosphoric acid is used to treat the washing water. Through the collaborative cooperation of the filtration unit, heat exchange unit, resin adsorption unit, ultrafiltration unit, and phosphoric acid concentration unit, the phosphoric acid resources in the washing water are effectively enriched in the recycled phosphoric acid. The water quality changes of each treatment unit in this process are shown in Figure 2 .

[0193] Then, for the first supernatant composed of the first product water and the second product water, the Figure 1 recycled product water preparation section is used for treatment. The obtained recycled product water has a large water volume, with a TDS content as low as 0.8 mg / L and a sulfate content as low as 0.55 mg / L, and can be recycled for the iron phosphate synthesis process or other processes. The water quality changes of each treatment unit in this process are shown in Figure 3 .

[0194] Finally, for the second mixture composed of all by-product wastewaters and reaction mother liquors generated in the process of recycling and purifying phosphoric acid and preparing recycled product water, the Figure 1 deep purification and discharge section is used for treatment. Among them, the dosage of sodium hydroxide solution in the chemical reaction tank 331 is 0.081 m 3 / h, the dosage of calcium hydroxide solution is 0.432 m 3 / h, the dosage of sulfuric acid in the pH adjustment tank 341 is 0.1 m 3 / h, the dosage of ferrous sulfate solution in the Fenton reaction tank 342 is 11.83 m 3 / h, and the dosage of hydrogen peroxide solution is 6.13 m 3 / h. Eventually, the pollutants are deeply removed. The water quality changes of each treatment unit in this process are shown in Figure 4 .

[0195] It has been verified that by using the treatment method and treatment system of the present utility model to treat the wastewater from iron phosphate production, the benefits generated from recycling phosphoric acid and recycled water are significant, far higher than the equipment investment and operating costs of the treatment system, and ultimately bring excellent economic benefits to the enterprise, making it very suitable for use by iron phosphate production enterprises.

[0196] The above has described the relevant content of the embodiments of the utility model provided in this specification. Those of ordinary skill in the art will be able to implement the embodiments of the utility model provided in this specification based on these descriptions. Based on the above content of the embodiments of the utility model provided in this specification, all other preferred embodiments and examples obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the embodiments of the utility model provided in this specification.

Claims

1. A treatment system for wastewater from ferric phosphate production, characterized by: include: The reuse phosphoric acid purification and recovery section is used to treat the wash water to obtain the reuse phosphoric acid and the first clear liquid; The recycled produced water preparation section is used to treat the first clear liquid to obtain an impurity concentrated liquid and recycled produced water; The deep purification and discharge section is used to purify the impurity concentrate and reaction mother liquor to obtain qualified produced water; Wherein, the reuse phosphoric acid purification and recovery section includes: A filtering unit, wherein the filtering unit filters the wash water and outputs a filtrate; A heat exchange unit, wherein the heat exchange unit cools the filtrate and then outputs a coolant; A resin adsorption unit, wherein the resin adsorption unit performs adsorption treatment on the coolant and then outputs adsorbed liquid; An ultrafiltration unit, wherein the ultrafiltration unit performs ultrafiltration treatment on the adsorbed liquid and outputs ultrafiltration clear liquid; The phosphoric acid concentration unit concentrates the ultrafiltration clear liquid and outputs the recycled phosphoric acid and the first clear liquid.

2. The system for treating wastewater from iron phosphate production according to claim 1, characterized in that: The filtration unit comprises a precision filter (111) and a first filter press (112); the precision filter (111) filters the wash water to obtain a filtrate and a filter cake; the filtrate is stored in a filtrate storage tank (113); the filter cake is collected by back-blowing to form a slag liquid which is stored in a slag liquid storage tank (114); and the first filter press (112) filters the slag liquid to obtain a first filtrate which flows back into the wash water storage tank (100).

3. The system for treating wastewater from iron phosphate production according to claim 1, characterized in that: The heat exchange unit comprises a plate heat exchanger (120).

4. The system for treating wastewater from ferric phosphate production according to claim 1, characterized in that: The resin adsorption unit comprises a resin adsorption tower (131), a resin regeneration mechanism and a resin elution mechanism. A strong acid cationic resin is arranged in the resin adsorption tower (131). The resin regeneration mechanism uses dilute sulfuric acid to spray and regenerate the strong acid cationic resin to obtain a resin regeneration liquid. The resin elution mechanism uses pure water to elute the strong acid cationic resin to obtain an elution liquid which flows back into the washing water storage tank (100).

5. The system for treating wastewater from ferric phosphate production as claimed in claim 4, characterized in that: The resin regeneration mechanism comprises a graphite diluter (132), wherein the graphite diluter (132) processes pure water and concentrated sulfuric acid to obtain dilute sulfuric acid for spray regeneration; the resin eluting mechanism comprises a first pipe (1331) for inputting pure water into the graphite diluter (132) and a second pipe (1332) for inputting pure water into the resin adsorption tower (131).

6. The system for treating wastewater from ferric phosphate production as claimed in claim 5, characterized in that: The resin adsorption unit further comprises a post-adsorption liquid storage tank (134), a concentrated sulfuric acid storage tank, a dilute sulfuric acid storage tank (135), a resin regeneration liquid storage tank (136), a washing liquid storage tank (137) and a pure water storage tank (138).

7. The system for treating wastewater from ferric phosphate production according to claim 1, characterized in that: The ultrafiltration unit comprises an ultrafiltration device (141) and an ultrafiltration clear liquid storage tank (142), and the ultrafiltration device (141) adopts an internal pressure hollow PES membrane.

8. The system for treating wastewater from ferric phosphate production according to claim 1, characterized in that: The ultrafiltration concentrate obtained after the ultrafiltration unit filters the adsorbed liquid is refluxed into the wash water storage tank (100).

9. The system for treating wastewater from ferric phosphate production according to claim 1, characterized in that: The phosphoric acid concentration unit comprises: A first reverse osmosis device (151), wherein the first reverse osmosis device (151) performs a concentration treatment on the ultrafiltration clear liquid to obtain a phosphoric acid concentrate and a first produced water; A second reverse osmosis device (152), wherein the second reverse osmosis device (152) performs a concentration treatment on the phosphoric acid concentrate to obtain recycled phosphoric acid and second produced water; wherein the first produced water and the second produced water constitute the first clear liquid.

10. The system for treating wastewater from ferric phosphate production according to claim 9, characterized in that: The phosphoric acid concentration unit further includes a phosphoric acid concentrate storage tank (153), a recycled phosphoric acid storage tank (154) and a first clear liquid storage tank (155).

Images