CN115340240B

CN115340240B - Comprehensive treatment method for nickel-cobalt-manganese ternary lithium battery wastewater

Info

Publication number: CN115340240B
Application number: CN202211020981.7A
Authority: CN
Inventors: 赖浪; 仇雅丽; 刘勇奇; 刘长根; 巩勤学; 李长东
Original assignee: Hunan Brunp Recycling Technology Co Ltd; Guangdong Brunp Recycling Technology Co Ltd
Current assignee: Hunan Brunp Recycling Technology Co Ltd; Guangdong Brunp Recycling Technology Co Ltd
Priority date: 2022-08-24
Filing date: 2022-08-24
Publication date: 2023-06-16
Anticipated expiration: 2042-08-24
Also published as: WO2024040904A1; CN115340240A

Abstract

The invention discloses a comprehensive treatment method of nickel-cobalt-manganese ternary lithium battery wastewater, which comprises the following steps of: according to the mole ratio of nitrogen, magnesium and phosphorus of (9-11): (1.5-2.5): and 1, mixing the phosphorus-containing wastewater, the magnesium-containing wastewater and the ammonia-containing wastewater to obtain a mixed solution, reacting, and aging to obtain mother solution and struvite. According to the comprehensive treatment method, phosphorus-containing wastewater, magnesium-containing wastewater and ammonia nitrogen-containing wastewater generated in different working procedures in the lithium battery recovery process are mixed to react and respectively serve as a phosphorus source, a magnesium source and a nitrogen source to form struvite, phosphorus and magnesium resources in the wastewater are utilized to the maximum extent, the comprehensive treatment method can be used as high-quality phosphate fertilizer to be directly used in agriculture and forestry, has higher added value, and does not generate solid waste containing phosphorus or magnesium. In addition, the reaction process does not need process facilities with excessive occupied area.

Description

Comprehensive treatment method for nickel-cobalt-manganese ternary lithium battery wastewater

Technical Field

The application relates to the technical field of wastewater treatment, in particular to a comprehensive treatment method for nickel-cobalt-manganese ternary lithium battery wastewater.

Background

Ternary lithium batteries, particularly nickel cobalt lithium manganate ternary lithium batteries, are of great interest due to their high energy density. The increasing demand of lithium batteries is accompanied by the generation of a large number of waste lithium batteries, and how to effectively recycle retired lithium batteries, alleviate corresponding resource shortage and environmental problems, and gradually become an important problem in the lithium battery industry. At present, an attempt is made to directly prepare a nickel-cobalt-manganese ternary precursor material by taking a product of the recycled waste lithium battery as a raw material after recycling the waste lithium battery. However, in the above-mentioned processes, various waste water is still generated at different stages, for example, in the lithium recovery stage, lithium ions are generally recovered by precipitation using phosphate, which results in the generation of phosphorus-containing waste water; other refining stages like nickel-cobalt-manganese sulfate and synthesis stages of the ternary nickel-cobalt-manganese precursor also respectively generate magnesium-containing wastewater and ammonia-containing wastewater.

For the above-mentioned waste water, there are different treatment methods at present, for example, the common treatment mode of the waste water containing magnesium is that the magnesium element is converted into magnesium hydroxide through liquid-alkali value adjustment mixing reaction sedimentation, solid waste and waste liquid are formed after filter pressing, the waste liquid returns to a sedimentation tank, and the produced water in the sedimentation tank is filtered, the value adjustment is carried out to neutral, and then the waste liquid is discharged outwards or MVR is evaporated; and similarly, the phosphorus-containing wastewater is subjected to mixing reaction and sedimentation through calcium hydroxide solution, phosphorus element in the wastewater is converted into calcium phosphate, solid waste and waste liquid are formed after filter pressing, the waste liquid returns to a sedimentation tank, and water produced by the sedimentation tank is filtered, and the water is adjusted to be neutral and then discharged outwards or MVR is evaporated. It can be seen that the treatment mode of the wastewater consumes liquid alkali or calcium hydroxide, which can cause the increase of total salt and the increase of hardness in the wastewater, and a sedimentation tank with larger occupation of land is needed to finish the treatment, and the obtained magnesium hydroxide solid waste or calcium phosphate solid waste after sedimentation can be used as the preparation auxiliary material of other chemical industrial products by multiple processes, and has low natural added value.

Therefore, it is necessary to provide a comprehensive treatment method for wastewater, which utilizes phosphorus and magnesium resources in the wastewater to the greatest extent, realizes the reduction and even zero output of phosphorus-containing solid waste and magnesium-containing solid waste, can obtain high-added-value byproducts, and has small occupied area for required facilities.

Disclosure of Invention

The present application aims to solve at least one of the technical problems existing in the prior art. Therefore, the application provides a comprehensive treatment method for nickel-cobalt-manganese ternary lithium battery wastewater. The processing method has the advantages of simple processing flow, high processing efficiency and low processing cost.

In a first aspect of the present application, there is provided a method for the integrated treatment of nickel-cobalt-manganese ternary lithium battery wastewater, the wastewater comprising phosphorus-containing wastewater, magnesium-containing wastewater and ammonia-containing wastewater, the integrated treatment method comprising the steps of:

s1: according to the mole ratio of nitrogen, magnesium and phosphorus of (9-11): (1.5-2.5): 1, mixing phosphorus-containing wastewater, magnesium-containing wastewater and ammonia-containing wastewater to obtain mixed liquor;

s2: and (5) after the mixed solution reacts, ageing and separating to obtain mother solution and struvite.

The comprehensive treatment method according to the embodiment of the application has at least the following beneficial effects:

according to the comprehensive treatment method, phosphorus-containing wastewater, magnesium-containing wastewater and ammonia nitrogen-containing wastewater generated in different working procedures in the ternary lithium battery generation process are mixed to react and respectively serve as a phosphorus source, a magnesium source and a nitrogen source to form struvite, phosphorus and magnesium resources in the wastewater are utilized to the maximum extent, the comprehensive treatment method can be used as high-quality phosphate fertilizer to be directly used in agriculture and forestry, has higher added value, and does not generate solid wastes containing phosphorus or magnesium. In addition, the reaction process does not need process facilities with excessive occupied area.

In addition, in the comprehensive treatment method, the components in the ternary lithium battery wastewater are complex, the characteristics of element composition are considered, and in order to reduce the total amount of mother liquor generated after the reaction, the treatment time is prolonged due to overlarge amount of subsequent salt recovery treatment, so that the treatment process is generally adoptedThe wastewater generated in the production line is used as a material for reaction without dilution, thus being different from struvite MgNH ₄ PO ₄ ·6H ₂ Nitrogen, magnesium, phosphorus 1 in O: 1:1, and the molar ratio of the process is (9-11): (1-3): 1, and the nitrogen-magnesium-phosphorus ratio is used for reaction. On the other hand, according to the chemical equilibrium principle, the reaction process is controlled through higher ammonia concentration conditions, and the aging time required after the reaction is reduced.

In some embodiments of the present application, the molar ratio of nitrogen, magnesium and phosphorus is (9-11): (1.5-2.5): and 1, mixing the phosphorus-containing wastewater, the magnesium-containing wastewater and the ammonia-containing wastewater to obtain a mixed solution.

In some embodiments of the present application, S1 comprises:

s11: according to the mole ratio of nitrogen to phosphorus of (9-11): 1, mixing phosphorus-containing wastewater and ammonia-containing wastewater to obtain nitrogen-phosphorus wastewater;

s12: and then according to the mole ratio of magnesium to phosphorus of (1-3): and 1, adding magnesium-containing wastewater into the nitrogen-phosphorus wastewater, and adjusting the pH value to 8-10 to obtain a mixed solution.

In the preparation process, the phosphorus-containing wastewater and the ammonia-containing wastewater are mixed to obtain nitrogen-phosphorus wastewater, and then the magnesium-containing wastewater is added for regulating the value to react, so that struvite rather than magnesium phosphate, magnesium hydroxide and other products are formed as much as possible, the output of magnesium-containing solid waste is reduced, and the yield and purity of struvite are improved.

In some embodiments of the present application, the ammonia-containing wastewater is filtered to remove valuable metal insolubles and adjust the pH to 5-9.5 prior to mixing. In the ammonia-containing wastewater, there may be a certain content of insoluble substances (such as hydroxide) of at least one valuable metal element such as nickel, cobalt, manganese, etc., and the insoluble substances may be doped into the product during the subsequent crystallization of struvite, thereby affecting the purity of struvite. Therefore, it is necessary to remove these metal insolubles by a suitable method in advance, and the filtration method is selected for removal from the viewpoint of the treatment cost and the simplicity of the process. In addition, since the pH of the raw materials affects the pH of the reaction system and thus affects the occurrence of side reactions, and the recovery efficiency of nitrogen, phosphorus and magnesium in wastewater and the crystallization of struvite change, further adjustment of the value of the nitrogen-containing wastewater after filtration to remove valuable metal insoluble substances is comprehensively considered.

In some embodiments of the present application, the ammonia-containing wastewater is an ammonia sulfate-containing wastewater.

In some embodiments of the application, the pH value of the ammonia-containing wastewater is 12-14, and the ammonia nitrogen concentration is 0.1-3 g/L.

In some embodiments of the present application, the solid content of the valuable metal insoluble in the ammonia-containing wastewater is 0.001-0.02 g/L, and the particle size distribution D50 of the valuable metal insoluble particles is 0.1-10 μm.

In some embodiments of the present application, the valuable metal insolubles in the ammonia-containing wastewater comprise predominantly nickel cobalt manganese hydroxides.

In some embodiments of the application, after the ammonia-containing wastewater is filtered to remove valuable metal insoluble substances, the concentration of nickel element in the filtrate is 0.1-2 mg/L, the concentration of cobalt element is 0.1-2 mg/L, and the concentration of manganese element is 0.1-2 mg/L. In the filtered filtrate, metal elements such as nickel, cobalt, manganese and the like mainly exist in the form of soluble complex.

In some embodiments of the present application, the filtration of the valuable metal insolubles in the ammonia-containing wastewater employs a membrane filter, such as an organic membrane filter or an inorganic membrane filter, preferably an organic membrane filter.

In some embodiments of the present application, the pore size of the filter element of the organic membrane filter used for filtering valuable metal insoluble substances in the ammonia-containing wastewater ranges from 0.3 μm to 0.5 μm.

In some embodiments of the present application, the material of the organic membrane filter used for filtering the valuable metal insoluble in the ammonia-containing wastewater is at least one of steel materials such as 304 stainless steel, 316L stainless steel, and the like.

In some embodiments of the present application, the filter element material of the organic membrane filter used for filtering valuable metal insoluble substances in the ammonia-containing wastewater is PVC or ceramic membrane.

In some embodiments of the present application, the ammonia-containing wastewater after filtering to remove valuable metal insolubles further includes adjusting the pH to be weakly acidic, neutral or weakly alkaline, for example, adjusting the pH to about 5 to 9.5. In the step, the reagent used for adjusting the pH can be dilute sulfuric acid, for example, dilute sulfuric acid with the concentration of 0.5-3.0 mol/L, and the specific method for adjusting the pH by the reagent can be self-control feeding by pump interlocking.

In some embodiments of the present application, the magnesium-containing wastewater is adsorbed to remove oil before mixing. The oil content in the magnesium-containing wastewater is used as an organic matter to influence the quality of struvite crystal particles, and the oil content or COD value in mother liquor generated after the reaction is also influenced, so that the oil content in the magnesium-containing wastewater is removed in advance before the magnesium-containing wastewater is used as a reaction raw material to be mixed so as to improve the quality of struvite crystal, and the subsequent possible MVR evaporation process is facilitated.

In some embodiments of the present application, the magnesium-containing wastewater is magnesium-containing sulfate wastewater.

In some embodiments of the application, the pH value of the magnesium-containing wastewater is 1-3, and the concentration of magnesium element in the magnesium-containing wastewater is 5-25 g/L.

In some embodiments of the application, the concentration of nickel element in the magnesium-containing wastewater is 0.1-2 mg/L, the concentration of cobalt element is 0.1-2 mg/L, the concentration of manganese element is 0.1-3 mg/L, the concentration of chlorine element is 0.1-1 g/L, the concentration of sodium element is 5-10 g/L, the concentration of calcium element is 1-3 mg/L, and the oil content is less than or equal to 10mg/L.

In some embodiments of the present application, the means of degreasing is adsorption, and alternative materials for the adsorbent material include, but are not limited to, activated carbon, porous polymers, porous alumina, porous silica, molecular sieves, kaolin, titanium dioxide, ceria, and like porous materials. Preferably, activated carbon is used for adsorption degreasing. The source of the activated carbon can be wood, cotton, peat, coal, coconut shell, asphalt, coke, coal tar, fruits, nuts, carbon black, graphite and the like, and the size of the activated carbon can be different from 20-100 meshes. It is understood that when activated carbon is used for adsorption, at least one of concentrated water (electric conductivity 150 to 350. Mu.s/cm), pure water (electric conductivity 0.5 to 25. Mu.s/cm), tap water (electric conductivity 150 to 220. Mu.s/cm) and the like is preferably used for back washing pretreatment, and the solid-to-liquid ratio of the activated carbon and water during pretreatment is preferably not less than 1: and 5, the washing times can be 2-5 times, and the back flushing can be automatically controlled by using a pressure gauge-valve-pump interlock.

In some embodiments of the present application, the phosphorus-containing wastewater is a phosphorus-containing sulfate wastewater.

In some embodiments of the present application, the pH value of the phosphorus-containing wastewater is 5-9, and the phosphorus element concentration is 0.5-3 g/L.

In some embodiments of the application, the concentration of nickel element in the phosphorus-containing wastewater is 0.1-2 mg/L, the concentration of cobalt element is 0.1-2 mg/L, the concentration of manganese element is 0.1-1 mg/L, the concentration of chlorine element is 0.1-1 g/L, the concentration of sodium element is 0.5-2.0 g/L, the concentration of calcium element is 1-3 mg/L, and the concentration of oil content is less than or equal to 3mg/L. It is understood that when the phosphorus-containing or ammonia-containing wastewater contains an oil component at a certain concentration, it is also contemplated that the phosphorus-containing or ammonia-containing wastewater may be subjected to adsorption degreasing treatment in advance before mixing.

In some embodiments of the present application, when mixing the ammonia-containing wastewater and the phosphorus-containing wastewater, the stirring speed of the mixing is controlled to be 50-200 rpm, the temperature is 10-35 ℃, and the mixing time is 5-30 min.

In some embodiments of the application, when adding magnesium-containing wastewater to nitrogen-phosphorus wastewater, adjusting the pH to 8-10, at least one of liquid caustic soda, ionic membrane caustic soda, filtered ammonia-containing wastewater and the like can be adopted to adjust the pH of the solution. Further, the pH is adjusted to 8 to 9.5. In some embodiments of the present application, pH meter-pump interlocking self-controlled dosing may be used when the filtered ammonia-containing wastewater is used to adjust pH.

In some embodiments of the application, after adding magnesium-containing wastewater to nitrogen-phosphorus wastewater and adjusting pH, controlling the rotation speed of stirring reaction to be 10-60 rpm, the temperature to be 15-25 ℃, the reaction time to be 0.1-5 h, and the further reaction time to be 0.5-1 h.

In some embodiments of the present application, after adding magnesium-containing wastewater to the nitrogen-phosphorus wastewater to adjust the pH and completing the reaction of the mixed solution, standing and aging are performed, the temperature may be kept the same as the reaction temperature, for example, may be 15-25 ℃. After the aging is finished, struvite and aged mother liquor can be separated at least through a filter pressing mode and the like, and specifically, solid-liquid separation can be carried out by adopting a membrane filter press or a box filter press and the like. In some modes, the struvite obtained by solid-liquid separation is subjected to drying and other modes to remove water, for example, the struvite can be dried at a low temperature for 4-8 hours. The low-temperature drying equipment can be a disc dryer or a paddle dryer with an exhaust function.

In some embodiments of the application, the total weight percentage of nickel, cobalt and manganese in the dried struvite is less than or equal to 0.0001%, and meanwhile, the struvite has higher purity and can reach 97.5-99.8%.

In some embodiments of the present application, when the concentrations of the valuable transition metal elements such as nickel, cobalt, manganese and the like in the mother liquor are all very low, for example, all lower than 5, 2, 1, 0.5, 0.2 and 0.1mg/L, the mother liquor can be directly recycled into the mixed liquor. On the other hand, when the concentration of these valuable transition metal elements is high, for example, higher than 0.1, 0.2, 0.5, 1, 2, 5mg/L, they exist in the form of complex in the mother liquor, and it is difficult to separate them by filtration or the like, so that it is necessary to further reduce ammonia nitrogen in the mother liquor by deamination before removing them.

In some embodiments of the application, when the concentration of the valuable heavy metal elements such as nickel, cobalt, manganese and the like in the mother liquor is higher, the valuable heavy metal elements can be further treated in the modes of removing ammonia nitrogen, magnesium and phosphorus, valuable heavy metal and the like through breakpoint chlorination and aeration blowing. Specifically, when the content of the guano is higher, an outlet is needed to be found for valuable heavy metals, magnesium and other elements in the reaction system, so that the increase of the content of the nickel cobalt manganese heavy metals and magnesium hydroxide caused by the increase of the recycling times of the mother solution is prevented, and the quality of the formed guano is finally influenced. In addition, the filtration of magnesium hydroxide and the like by using a filter is extremely difficult to backwash, and if the recovery process is directly operated in a filtration manner, the recovery process is conversely more complicated.

In some embodiments of the present application, the mother liquor has a pH of 7.0 to 8.0.

In some embodiments of the present application, the integrated processing method further includes S3: the mother liquor is subjected to break point chlorination and aeration blowing to remove ammonia nitrogen. Because the filtered ammonia-containing wastewater is adopted in the reaction materials, a large amount of ammonia nitrogen exists in the mother liquor, and therefore, the ammonia nitrogen in the mother liquor is efficiently and simply removed by means of break point chlorination and aeration stripping; meanwhile, as ammonia nitrogen is removed, complex of valuable metal possibly existing in the mother solution can be converted into precipitate and can be removed, so that the purity of the soluble salt component in the mother solution is improved.

In some embodiments of the present application, S3 comprises:

s31: sodium hypochlorite or chlorine gas is introduced into the mother solution for deamination treatment;

s32: and regulating the pH value of the deaminated mother liquor to be alkaline, heating, aerating, and blowing off residual ammonia and residual chlorine.

When the primary deamination is carried out by the first break point chlorination, at least one of sodium hypochlorite and chlorine is used, so that the pH of the mother liquor needs to be controlled to be at least neutral in order to oxidize ammonia gas into nitrogen gas, and the pH of the mother liquor needs to be controlled to be alkaline in the aeration stripping, therefore, if the aeration stripping is carried out by the method of firstly adjusting the value of alkaline substances to be alkaline and then carrying out the aeration stripping, the break point chlorination is carried out after the reaction is finished by adding acidic substances to be neutral. If the subsequent need to continue to remove phosphorus and magnesium, the value still needs to be set to alkaline again. In contrast, the times of value adjustment are reduced by chlorination at break points and aeration stripping, the process is simpler, and the construction cost of treatment facilities, the cost of auxiliary materials and the total salt produced by subsequent evaporation are also more.

In some embodiments of the present application, sodium hypochlorite is used for breakpoint chlorination.

In some embodiments of the application, the oil content in the mother liquor can be reduced by 5-10% at the same time of removing ammonia nitrogen by the break point chlorination reaction.

In some embodiments of the present application, an online ammonia nitrogen detection instrument may be used to automatically sample and detect ammonia nitrogen concentration in the mother liquor.

In some embodiments of the present application, the molar ratio of sodium hypochlorite or chlorine gas added by adding chlorine at the break point to ammonia nitrogen in the mother solution (chlorine element and nitrogen element) is (4-12): 1, for example, may be 4: 1. 5: 1. 6: 1. 7: 1. 8:1. 9: 1. 10: 1. 11: 1. 12:1, further may be (6 to 10): 1,8:1. in some embodiments of the present application, hypochlorous acidSodium can be added in the form of a solution, and the concentration of the sodium hypochlorite solution can be 10-100 kg/m ³ ，20~90 kg/m ³ ，30~80 kg/m ³ ，40~60 kg/m ³ . The sodium hypochlorite solution can be synthesized by DCS or PLC programs through the detection data of an online ammonia nitrogen detector, the detection data of a liquid level meter, the feeding time, the reaction time and other data, so that the adding amount is controlled.

In some embodiments of the present application, after denitrification treatment of the mother liquor by adding chlorine at the break point, the escaped nitrogen, ammonia, chlorine and water vapor can be absorbed by an absorption tower. In some embodiments, the absorption liquid in the absorption tower uses at least one of concentrated water (electric conductivity 150-350 μs/cm), pure water (electric conductivity 0.5-25 μs/cm), and tap water (electric conductivity 150-220 μs/cm).

In some embodiments of the present application, the pH of the mother liquor after deamination treatment may be specifically adjusted to 12-14, and the reagent used for adjusting the pH may be liquid caustic soda, ionic membrane caustic soda, etc. as described above, and pH meter-pump interlocking self-control feeding may be used.

In some embodiments of the present application, the heating after adjusting the pH to the alkaline may be to raise the temperature to 85-95 ℃, for example, a plate heat exchanger may be used to raise the temperature, and the temperature control in the heating process may be controlled by using a thermometer-steam valve interlock.

In some embodiments of the application, compressed air can be used as an aeration air source during aeration stripping, the air pressure of the compressed air can be controlled to be 0.3-0.7 MPa, and the treatment time of aeration stripping can be regulated and controlled according to the ammonia concentration in the mother liquor through a DCS or PLC program. In some embodiments, the aeration stripping reaction is completed when the ammonia concentration is less than or equal to 10mg/L.

In some embodiments of the present application, the concentration of residual ammonia in the mother liquor after aeration stripping is less than or equal to 10mg/L, and the concentration of residual chlorine is less than or equal to 0.5mg/L.

In some embodiments of the present application, nitrogen, ammonia, chlorine, and water vapor escaping from aeration stripping can all be absorbed using an absorber. In some embodiments, the absorption liquid in the absorption tower uses at least one of concentrated water (electric conductivity 150-350 μs/cm), pure water (electric conductivity 0.5-25 μs/cm), and tap water (electric conductivity 150-220 μs/cm).

In some embodiments of the present application, the absorption liquid in the absorption tower can be used for preparing sodium hypochlorite after absorbing the chlorine with set concentration.

In some embodiments of the present application, the oil content in the mother liquor after aeration stripping is reduced by 1 to 5%.

In some embodiments of the present application, the integrated treatment method further comprises: s4: and (5) press-filtering the mother liquor to obtain filtrate and filter residues. After ammonia nitrogen is removed, the mother liquor also contains a certain amount of phosphorus and magnesium, so that a precipitate mainly containing magnesium phosphate and magnesium hydroxide which are insoluble in the filtrate is obtained by a filter pressing mode.

In some embodiments of the present application, the filtrate obtained by pressure filtration is subjected to salt recovery treatment after filtration again to remove insoluble materials. Since the insoluble matter is unlikely to be all involved in the formation of the filter residue during the press filtration, the filtrate is subjected to a filtration treatment again after the press filtration to remove the insoluble components as much as possible, mainly including at least one of nickel-cobalt-manganese hydroxide, magnesium phosphate, magnesium hydroxide, and the like, which are different depending on the specific composition of the three kinds of wastewater, the mother liquor, and the specific selection of the parameters of the foregoing operation steps. In some embodiments, the salt recovery process may be performed by evaporation using an MVR system, for example.

In some embodiments of the present application, the water content of the filter residue is 40.2-45.1%.

In some embodiments of the application, in S4, the concentration of nickel, cobalt and manganese in the filtrate obtained by filtering and filtering the filtrate again to remove insoluble substances is less than or equal to 0.5mg/L, the concentration of magnesium element is less than or equal to 3mg/L, the concentration of phosphorus element is less than or equal to 1mg/L, and the concentration of ammonia element is less than or equal to 10mg/L.

In some embodiments of the present application, the re-filtration uses a membrane filter, which may be, for example, an organic membrane filter.

In some embodiments of the present application, after the organic membrane filter is backwashed after the re-filtration, the rinsed water participates in the filter pressing of the mother liquor after removal of ammonia nitrogen.

In some embodiments of the present application, the filter residue obtained by the pressure filtration in S4 and the insoluble matter obtained by the secondary filtration are adjusted in pH to obtain a magnesium solution, and the magnesium solution is recycled to the mixed liquor. Insoluble matters such as filter residues and the like stored are separated in the filter pressing and subsequent filter processes, and in order to realize zero output of magnesium solid waste, the insoluble matters are formed into a solution containing magnesium ions by adjusting the pH value, and then the solution is recycled into the mixed solution to participate in struvite formation again. As previously described, it will be appreciated that the magnesium solution may also contain trace amounts of nickel cobalt manganese as the insoluble material may also have nickel cobalt manganese hydroxide.

In some embodiments of the present application, the pH of the filter residue and insoluble matter obtained by the pressure filtration in S4 may be adjusted by using dilute sulfuric acid, for example, the pH may be adjusted to 2.0-3.5, and during the adjustment, pH meter-pump interlocking self-control feeding may be used. The concentration of the dilute sulfuric acid used for the adjustment may be, for example, 0.5 to 3.0mol/L.

In a second aspect of the present application, there is provided a comprehensive treatment system for wastewater, comprising a struvite production unit, the struvite production unit comprising:

a wastewater supply device for providing a phosphorus-containing wastewater, an ammonia-containing wastewater and a magnesium-containing wastewater;

the struvite synthesizing device is used for mixing the phosphorus-containing wastewater, the ammonia-containing wastewater and the magnesium-containing wastewater to obtain a mixed solution and reacting to generate struvite;

and the separating device is used for separating struvite from the mixed liquid so as to form mother liquid.

In some embodiments of the present application, a wastewater supply apparatus includes:

a phosphorus-containing wastewater supply device for supplying phosphorus-containing wastewater to the struvite synthesizing device;

the ammonia-containing wastewater supply device is used for providing ammonia-containing wastewater for the struvite synthesis device, and is also provided with a first filtering component which is used for filtering out valuable metal insoluble matters in the ammonia-containing wastewater;

and the magnesium-containing wastewater supply device is used for providing magnesium-containing wastewater for the struvite synthesizing device and is also provided with an oil removing component which is used for removing oil in the magnesium-containing wastewater.

In some embodiments of the present application, the phosphorus-containing wastewater supply device includes a phosphorus-containing wastewater reservoir.

In some embodiments of the present application, the ammonia-containing wastewater supply device includes a first organic film filter and a first organic film filter water producing tank, and the filter component is the first organic film filter.

In some embodiments of the present application, the magnesium-containing wastewater supply device includes a magnesium-containing wastewater tank and an adsorption column, which is an oil removal component.

In some embodiments of the present application, a struvite synthesis device comprises:

the bird droppings Dan Yici reaction tank and the bird droppings Dan Yici reaction tank are used for carrying out preliminary mixing on the phosphorus-containing wastewater and the ammonia-containing wastewater;

the struvite secondary reaction tank is used for receiving the product obtained by primary mixing in the struvite Dan Yici reaction tank and the magnesium-containing wastewater, and mixing to obtain a mixed solution;

the ageing tank is used for allowing the mixed solution to react to generate struvite and ageing to separate struvite crystals.

In some embodiments of the present application, the separation device comprises:

the first filter press is used for separating struvite crystals from the mixed liquid and forming mother liquid;

and the dryer is used for drying the separated struvite crystals.

In some embodiments of the present application, the integrated treatment system further comprises a mother liquor recovery unit comprising:

the ammonia removal device comprises a break point chlorination device and an aeration stripping device, and is used for sequentially carrying out break point chlorination and aeration stripping on the mother liquor to remove ammonia nitrogen;

the magnesium removing device is used for separating magnesium-containing precipitate from the mother solution after ammonia removal;

and the salt recovery device is used for separating soluble salt from the mother solution after magnesium removal.

In some embodiments of the present application, the mother liquor recovery unit further comprises a first liquid receiving tank for receiving mother liquor from the first filter press. The mother liquor received by the first liquid receiving tank is then guided into an ammonia removal device to enter subsequent recovery treatment.

In some embodiments of the present application, the breakpoint chlorination apparatus includes a reaction tank for providing a space for the mother liquor to react with sodium hypochlorite or chlorine gas. In some of these embodiments, the breakpoint chlorination apparatus further includes a sodium hypochlorite or chlorine gas supply member for supplying sodium hypochlorite or chlorine gas to the reaction tank.

In some embodiments of the present application, an aeration stripping apparatus includes an aeration stripping reaction tank and a heating member. In some of these embodiments, the heating component is a heat exchanger, such as a plate heat exchanger.

In some embodiments of the present application, the magnesium removal device comprises a second filter press for separating the magnesium-containing precipitate from the mother liquor by means of filter pressing.

In some embodiments of the present application, the magnesium removal apparatus further comprises a magnesium recovery apparatus for reprocessing the magnesium-containing precipitate into a magnesium-containing solution and recycling the magnesium-containing solution into the mixed liquor in the struvite synthesis apparatus.

In some embodiments of the present application, the salt recovery device comprises an MVR evaporation system.

In some embodiments of the present application, the salt recovery device further comprises a second filter element for filtering insoluble matter in the mother liquor. In some embodiments, the second filter element comprises a second organic film filter and a second organic film filter production tank, the mother liquor produced by the second organic film filter production tank is used to flow to the MVR evaporation system.

Additional aspects and advantages of the application 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 application.

Drawings

Fig. 1 is a flow chart of a comprehensive treatment method of ternary lithium battery wastewater in an embodiment of the present application.

FIG. 2 is a PID diagram of an integrated wastewater treatment system in an embodiment of the present application. Wherein A-G respectively represent phosphorus-containing wastewater, ammonia-containing wastewater, a high-pressure air source, magnesium-containing wastewater, liquid alkali, sodium hypochlorite and high-pressure steam.

Reference numerals: the device comprises a phosphorus-containing wastewater storage tank 1, an ammonia-containing wastewater storage tank 2, a first organic film filter 3, a first organic film filter water producing tank 4, a guano Dan Yici reaction tank 5, a guano stone secondary reaction tank 6, an aging tank 7, a first filter press 8, a magnesium-containing wastewater storage tank 9, an adsorption column 10, a reaction tank 11, a first liquid receiving tank 12, a second filter press 13, an aeration stripping reaction tank 14, a plate heat exchanger 15, a disc dryer 16, a second liquid receiving tank 17, a second organic film filter 18, a second organic film filter water producing tank and an MVR evaporation system 20.

Detailed Description

The conception and technical effects produced by the present application will be clearly and completely described below in connection with the embodiments to fully understand the objects, features and effects of the present application. It is apparent that the described embodiments are only some embodiments of the present application, but not all embodiments, and that other embodiments obtained by those skilled in the art without inventive effort based on the embodiments of the present application are within the scope of the present application.

The following detailed description of embodiments of the present application is exemplary and is provided merely for purposes of explanation and not to be construed as limiting the application.

In the description of the present application, the meaning of a number is one or more, the meaning of a number is two or more, and greater than, less than, exceeding, etc. are understood to exclude the present number, and the meaning of a number above, below, within, etc. are understood to include the present number. The description of the first and second is for the purpose of distinguishing between technical features only and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated. In the following description, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in an order different from that in the flowchart.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of the present application only and is not intended to be limiting of the present application.

In the description of the present application, a description with reference to the terms "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The following description is made with reference to specific examples.

Example 1

In this embodiment, the ammonia-containing wastewater, the phosphorus-containing wastewater and the magnesium-containing wastewater generated in the recovery process of the nickel-cobalt-manganese ternary lithium battery are to be comprehensively treated.

Wherein the pH value of the ammonia-containing wastewater is 13, the ammonia nitrogen concentration, P, mg, ni, co, mn and the oil content are shown in Table 1, and the particle diameter D50 of the nickel-cobalt-manganese insoluble particles is about 1 μm.

The pH value of the magnesium-containing wastewater is 2, the contents of P and Mg, ni, co, mn and the oil content are shown in Table 1, cl is 0.1-1 g/L, na is 5-10 g/L, and Ca is 1-3 mg/L.

The pH value of the phosphorus-containing wastewater is 7, the contents of P and Mg, ni, co, mn and the oil content are shown in Table 1, cl is 0.1-1 g/L, na is 0.5-2 g/L, and Ca is 1-3 mg/L.

The comprehensive treatment method, referring to fig. 1, comprises the following steps:

(1) Filtering the ammonia-containing wastewater by adopting a first organic film filter, filtering to remove insoluble nickel, cobalt and manganese substances in the ammonia-containing wastewater, generating filtered ammonia-containing wastewater in a water production tank of the first organic film filter, and regulating the pH value of the ammonia-containing wastewater to 8.37 by adding 1mol/L dilute sulfuric acid at room temperature;

(2) Introducing the phosphorus-containing wastewater in the phosphorus-containing wastewater storage tank and the ammonia-containing wastewater subjected to the value adjustment in the step (1) into a struvite primary reaction tank for mixing, and controlling the molar ratio of nitrogen to phosphorus to be 10.4:1, stirring and mixing for 5min at a rotating speed of 50 rpm;

(3) Pretreating magnesium-containing wastewater by adopting an activated carbon adsorption column, adsorbing oil in the magnesium-containing wastewater, then entering a magnesium-containing wastewater storage tank, and then introducing the magnesium-containing wastewater storage tank and the mixed liquid stirred in the step (2) into a struvite secondary reaction tank, wherein the molar ratio of nitrogen to magnesium to phosphorus is controlled to be 10.4:2:1, stirring at a rotating speed of 30rpm, adding the ammonia-containing wastewater filtered in the step (1) and before pH adjustment, adjusting the pH value of the mixed wastewater in the step to 9.41, stopping stirring after the pH value is stable, stirring and reacting for 30min, transferring into an aging tank, sealing (preventing ammonia escape loss), standing for 16h for aging treatment, detecting that the pH value of the aging liquid is about 8.13 when alum-like white struvite crystals appear, filtering the aging liquid by a first filter press, wherein filter residues are struvite crystals, and sending the struvite crystals into a disc dryer for drying at 30 ℃ for 4h.

(4) And (3) introducing the mother liquor of the aging liquid after the filter pressing in the step (3) into a first liquid receiving tank, measuring the pH value of the mother liquor to be 8.13, and detecting the concentration of ammonia, phosphorus, magnesium, nickel, cobalt, manganese and oil in the mother liquor. After transferring into a reaction tank, adding sodium hypochlorite solution (the effective chlorine concentration is 10 percent), and controlling the molar ratio of chlorine to nitrogen to be 8:1, stirring and reacting for 1.5h at a rotating speed of 50rpm, and detecting the concentration of residual ammonia to be 53.48mg/L after the reaction is finished.

(5) And (3) regulating the pH value of the mother liquor after the reaction in the step (4) to 12.87 by using liquid alkali, heating the mother liquor after the regulation to 90 ℃ by using a plate heat exchanger, and aerating in an aeration stripping reaction tank for 1.5h. The escaping gas is absorbed by tap water in the heating aeration process.

(6) And (3) performing filter pressing again on the mother liquor after the reaction in the step (5) by adopting a second filter press, enabling filter liquor after the filter pressing to enter a second liquid receiving tank, filtering out magnesium phosphate and magnesium hydroxide by using a second organic film filter, and enabling the filter liquor produced by a water producing tank of the second organic film filter to enter an MVR evaporation system for treatment.

(7) And (3) the filter residue generated by the pressure filtration in the step (6) and insoluble matters filtered by the organic film filter are subjected to pH adjustment by using 1mol/L dilute sulfuric acid to obtain magnesium sulfate solution, and the magnesium sulfate solution is recycled to the struvite secondary reaction tank to participate in struvite crystallization.

The contents of each component in the mother liquor obtained after the filter pressing in the step (4) and the filtrate produced by the filter pressing after the aeration of the mother liquor in the step (6) are shown in the following table 1, the composition of the struvite crystal produced in the step (3) is shown in the table 2, the contents of each component after the filter pressing in the step (6) and the drying of the filter residue are shown in the table 3, and the amounts of sodium hypochlorite solution (effective chlorine concentration 10%) in the step (4) and the liquid alkali (sodium hydroxide mass percentage is 30%) used in the adjustment in the step (5) are shown in the table 4.

TABLE 1 content of the Material Components (mg/L)

TABLE 2 content of components in struvite crystals (%)

TABLE 3 content of components (%)

TABLE 4 Material consumption

The integrated treatment system for wastewater involved in the above integrated treatment method is further described as follows:

the integrated treatment system comprises a struvite production unit and a mother liquor recovery unit, and referring to fig. 2, the struvite production unit comprises a wastewater supply device, a struvite synthesis device and a separation device.

The wastewater supply device comprises a phosphorus-containing wastewater supply device, an ammonia-containing wastewater supply device and a magnesium-containing wastewater supply device. The phosphorus-containing wastewater supply device comprises a phosphorus-containing wastewater tank 1 with a radar level gauge. The ammonia-containing wastewater supply device comprises an ammonia-containing wastewater storage tank 2 with a breather valve, a first organic membrane filter 3 with a pressure gauge and a back flushing function, and a first organic membrane filter water producing tank 4 with a breather valve and a radar liquid level gauge. The magnesium-containing wastewater supply device comprises a magnesium-containing wastewater storage tank 9 with a radar liquid level gauge and an adsorption column 10 formed by active carbon with a pressure gauge and a back flushing function.

The struvite synthesizing device comprises a struvite Dan Yici reaction tank 5 with a radar level gauge, a thermometer and a pH meter, a struvite secondary reaction tank 6 with a radar level gauge, a thermometer and a pH meter and an aging tank 7 with a radar level gauge, a thermometer and a pH meter.

The separation device comprises a first filter press 8 with an air-blowing function and a tray dryer 16.

The mother liquor recovery unit includes a first liquid receiving tank 12 for receiving the mother liquor, an ammonia removal device, a magnesium removal device, and a salt recovery device. The first liquid receiving tank 12 is provided with a radar level gauge.

The ammonia removal device comprises a break point chlorination device and an aeration stripping device. The break point chlorination equipment comprises a reaction tank 11 with a radar level gauge, a thermometer and a pH meter. The aeration stripping device comprises an aeration stripping reaction tank 14 with a radar liquid level meter, a thermometer and a pH meter and a plate heat exchanger 15 with a heat exchange water outlet section thermometer.

The magnesium removal device comprises a second filter press 13 with an air blowing function.

The salt recovery device comprises a second liquid receiving tank 17 with a radar liquid level meter, a second organic film filter 18 with a pressure meter and a back flushing function, a second organic film filter water producing tank 19 with the radar liquid level meter and an MVR evaporation system 20.

Wherein the first organic membrane filter and the second organic membrane filter are made of 304 stainless steel, and the filter element is a PVC membrane with the aperture of 0.4 mu m.

Example 2

The difference between the comprehensive treatment method for the ternary lithium battery wastewater and the embodiment 1 is that in the step (3), the molar ratio of nitrogen, magnesium and phosphorus is controlled to be 9:2:1, and meanwhile, the concentration of nickel, cobalt and manganese in the mother solution of the aging liquid after filter pressing is detected to be less than 0.5mg/L, so that the mother solution is directly recycled to the struvite secondary reaction tank for reuse.

Example 3

The difference between the comprehensive treatment method for the ternary lithium battery wastewater and the embodiment 1 is that in the step (3), the molar ratio of nitrogen, magnesium and phosphorus is controlled to be 11:2:1, introducing equimolar chlorine to replace sodium hypochlorite when deaminating by a break point chlorination method.

The overall treatment effect of examples 2 and 3 is substantially the same as that of example 1, and will not be described here again.

Example 4

The present example provides a comprehensive treatment method for ternary lithium battery wastewater, which is different from example 1 in that the phosphorus-containing wastewater, the filtered ammonia-containing wastewater and the deoiled magnesium-containing wastewater are directly treated with 10.4:2:1, and stirring the mixture in a reaction tank for reaction. The struvite crystals obtained in this example have a purity far below 97.7% converted to nitrogen.

Example 5

The difference between the method for comprehensively treating the ternary lithium battery wastewater and the method for comprehensively treating the ternary lithium battery wastewater in the embodiment 1 is that the steps (4) and (5) are different, and the method specifically comprises the following steps:

(4) And (3) introducing the mother liquor of the aging liquid after filter pressing in the step (3) into a liquid receiving tank, measuring the pH value of the mother liquor to be 8.13, detecting the concentration of ammonia, phosphorus, magnesium, nickel, cobalt, manganese and oil in the mother liquor, adding liquid alkali to adjust the pH value to be 12.87, heating the mother liquor after the adjustment to 90 ℃ through a plate heat exchanger, and aerating in an aeration stripping reaction tank for 1.5h. The escaping gas is absorbed by tap water in the heating aeration process.

(5) Adding 1mol/L dilute sulfuric acid into the aerated mother solution to adjust the value to be neutral, and then adding sodium hypochlorite solution, wherein the molar ratio of chlorine to nitrogen is controlled to be 8:1, stirring and reacting for 1.5 hours at a rotating speed of 50rpm, and then adding liquid alkali to readjust the pH value of the mother solution to 12.

It can be seen that after adjusting the sequence of aeration and break point chlorination, the pH needs to be adjusted multiple times in order for the reaction to proceed smoothly, so the process of this example is more complicated than that of example 1, and the cost is increased, and the total salt amount increases after MVR evaporation.

Comparative example 1

The comparison example provides a comprehensive treatment method for ternary lithium battery wastewater, which is different from the embodiment 1 in that in the step (3), the molar ratio of nitrogen, magnesium and phosphorus is controlled to be 5:2:1.

comparative example 2

The comparative example provides a comprehensive treatment method for ternary lithium battery wastewater, which is different from the embodiment 1 in that in the step (3), the molar ratio of nitrogen, magnesium and phosphorus is controlled to be 1:2:1.

comparative examples 1 and 2 used a lower ammonia concentration for the mixing reaction, and the aging time required for the final crystallization was much longer than 16 hours, and the struvite crystal grain size obtained by crystallization was also larger, and the application effect as a fertilizer was poor.

As can be seen from the above examples and comparative examples, the integrated treatment method provided in the present application has the following effects:

(1) The struvite is prepared by crystallization aging and filtration, a sedimentation tank is not used in the whole process, and the problem of large occupied area of a ternary precursor industrial wastewater treatment facility is solved.

(2) The method has the advantages that the method comprehensively treats residual ammonia and residual chlorine in the mother liquor wastewater prepared by struvite by using a break point chlorination method and an aeration stripping method, solves the problem that struvite synthesized by a sedimentation tank method cannot be discharged due to excessive residual ammonia, can reasonably control the adding amount of sodium hypochlorite in the whole deamination process by using an automatic control device, and reduces aeration time to the greatest extent.

(3) The phosphorus, the magnesium and the heavy metals in the wastewater after the secondary deamination of the synthetic struvite mother liquor are treated by using the combination of filter pressing and organic membrane filtration, a sedimentation tank is not needed, the occupied area of wastewater treatment facilities is small, the concentration of nickel, cobalt and manganese in the filtrate can be controlled to be below 0.5mg/L, the concentration of magnesium is below 3mg/L, the concentration of phosphorus is below 1mg/L and the concentration of ammonia is below 10mg/L.

(4) According to the treatment method, the problems of mother liquor disposal and recycling of residual phosphorus and magnesium resources in the mother liquor generated in the struvite preparation process are comprehensively considered, magnesium and phosphorus resources generated in the nickel-cobalt-manganese ternary cathode material production process are recovered to the greatest extent, high-added-value byproducts struvite are produced, and the used materials are very common in the ternary cathode material production industry and are very easy to obtain.

(5) The method solves the problems of large liquid alkali consumption and increase of total salt in wastewater in the treatment process of magnesium-containing sulfate wastewater in nickel-cobalt-manganese ternary precursor industrial wastewater, large occupied area of treatment facilities, solid waste of magnesium hydroxide and low added value of magnesium hydroxide.

(6) The method solves the problems of large consumption of calcium hydroxide and increase of total hardness of wastewater in the treatment process of the phosphate-containing sulfate wastewater in the industrial wastewater of the nickel-cobalt-manganese ternary precursor, large occupied area of treatment facilities, solid waste of calcium phosphate sludge, and low added value of calcium phosphate.

(7) The method is based on the current main stream ternary battery recovery process, integrates various waste water generated by the battery recovery process, comprehensively disposes the waste water, and can be widely popularized and used in the same industry of ternary battery recycling recovery.

(8) The application takes the industrial wastewater of the nickel-cobalt-manganese ternary precursor as the raw material, prepares the struvite with higher purity by virtue of the proposed process route, and the struvite product does not contain nickel-cobalt-manganese heavy metals, thus being capable of being popularized and applied to the recovery and separation of ammonia nitrogen, phosphorus and magnesium in the wastewater containing nickel, cobalt and manganese.

(9) The ammonia removal and deamination method with the break point chlorination method and the aeration stripping method can reduce oil content in the mother liquor to a certain extent, is favorable for the waste water filtration of the subsequent organic membrane filter and is favorable for the waste water evaporation of the subsequent MVR evaporation system.

The present application has been described in detail with reference to the embodiments, but the present application is not limited to the embodiments described above, and various changes can be made within the knowledge of one of ordinary skill in the art without departing from the spirit of the present application. Furthermore, embodiments of the present application and features of the embodiments may be combined with each other without conflict.

Claims

1. The comprehensive treatment method of the nickel-cobalt-manganese ternary lithium battery wastewater is characterized by comprising the following steps of:

s11: according to the mole ratio of nitrogen to phosphorus of (9-11): 1, mixing the phosphorus-containing wastewater and the ammonia-containing wastewater to obtain nitrogen-phosphorus wastewater, filtering the ammonia-containing wastewater to remove valuable metal insoluble substances before mixing, and adjusting the pH value to be 5-9.5;

s12: according to the mole ratio of magnesium to phosphorus of (1-3): 1, adding the magnesium-containing wastewater into the nitrogen-phosphorus wastewater, and adjusting the pH value to 8-10 to obtain the mixed solution, wherein the magnesium-containing wastewater is adsorbed to remove oil before mixing;

s2: after the mixed solution is reacted, standing and aging are carried out at 15-25 ℃, and filter pressing and separation are carried out to obtain mother solution and struvite;

s31: sodium hypochlorite or chlorine gas is introduced into the mother liquor to carry out deamination treatment;

s32: regulating the pH value of the deaminated mother liquor to 12-14, heating to 85-95 ℃, aerating, and blowing off residual ammonia and residual chlorine;

s4: and (3) filter-pressing the mother solution to obtain filtrate and filter residues, filtering the filtrate again to remove insoluble matters, then carrying out salt recovery treatment, regulating the pH value of the filter residues and the insoluble matters obtained by filtering again to be 2.0-3.5 to obtain a magnesium solution, and recycling the magnesium solution to the mixed solution obtained by the step (S12).

2. The integrated treatment system for wastewater for an integrated treatment process according to claim 1, comprising a struvite production unit comprising:

a wastewater supply device for providing a phosphorus-containing wastewater, an ammonia-containing wastewater, and a magnesium-containing wastewater;

the struvite synthesizing device is used for mixing the phosphorus-containing wastewater, the ammonia-containing wastewater and the magnesium-containing wastewater to obtain mixed liquid and reacting to generate struvite;

and the separating device is used for separating the struvite from the mixed liquid so as to form mother liquor.

3. The integrated treatment system according to claim 2, wherein the wastewater supply device comprises:

the ammonia-containing wastewater supply device is used for providing ammonia-containing wastewater for the struvite synthesis device, and is also provided with a filtering component for filtering valuable metal insoluble matters in the ammonia-containing wastewater;

the magnesium-containing wastewater supply device is used for providing magnesium-containing wastewater for the struvite synthesizing device, and is also provided with an oil removing component which is used for removing oil in the magnesium-containing wastewater.

4. The integrated treatment system of claim 2, further comprising a mother liquor recovery unit comprising:

the ammonia removal device comprises break point chlorination equipment and aeration stripping equipment, and is used for sequentially carrying out break point chlorination and aeration stripping on the mother liquor so as to remove ammonia nitrogen;

5. The integrated treatment system of claim 4, wherein the salt recovery device comprises an MVR evaporation system.