CN117446997A - Lithium battery recycling waste liquid treatment method - Google Patents

Abstract

This application discloses a lithium battery recycling waste liquid treatment method. The lithium battery recycling waste liquid includes the first anti-iron back liquid and phosphorus-containing waste water. The lithium battery recycling waste liquid treatment method includes the following steps: A post-antiferrous liquid is mixed with the phosphorus-containing wastewater, and the solid and liquid are separated to obtain a first intermediate liquid; the metal elements and organic matter in the first intermediate liquid are removed to obtain a second intermediate liquid; the second intermediate liquid is Evaporate and crystallize to obtain finished salt and condensed water. This application solves the technical problem of high cost in treating phosphorus-containing wastewater in related technologies.

Description

Lithium battery recycling waste liquid treatment method

Technical field

This application relates to the technical field of waste battery recycling, and in particular to a method for treating waste liquid from lithium battery recycling.

Background technique

During the recycling process of lithium-ion batteries, a large amount of phosphorus-containing wastewater will be generated. This type of wastewater has the characteristics of complex phosphorus forms, high salt content, and strong corrosiveness. The discharge of untreated phosphorus-containing wastewater into water bodies will cause algae growth to lose its ecological balance. Excessive phosphorus will cause red tides, algae blooms, and the death of fish and shrimp. Phosphorus pollution will cause various degrees of harm to the human body, soil, and water bodies. Therefore, phosphorus-containing wastewater needs to be treated.

At present, the treatment methods for phosphorus-containing wastewater include chemical methods, biological methods, coagulation flotation methods, physical and chemical methods, etc. These methods all require the addition of phosphorus removal agents to the phosphorus-containing wastewater. Waste battery recycling companies produce up to 100% of phosphorus-containing wastewater every year. Several hundred tons, the required phosphorus removal agent costs millions, and the cost of wastewater treatment is high.

Contents of the invention

The main purpose of this application is to provide a method for treating lithium battery recycling waste liquid, aiming to solve the high-cost technical problem of treating phosphorus-containing wastewater in related technologies.

In order to achieve the above purpose, the present application also provides a method for treating waste liquid from waste lithium battery recycling. The extracted finished product liquid refers to the aqueous phase obtained after extraction and separation during the process of recovering valuable metals from waste lithium batteries. The lithium The battery recycling waste liquid treatment method includes the following steps:

Mix the first anti-iron post liquid with the phosphorus-containing wastewater, and separate the solid and liquid to obtain a first intermediate liquid;

Remove metal elements and organic matter in the first intermediate liquid to obtain a second intermediate liquid;

The second intermediate liquid is evaporated and crystallized to obtain finished salt and condensed water.

Optionally, the step of removing metal elements and organic matter in the first intermediate liquid to obtain the second intermediate liquid includes:

Add alkali liquid to the first intermediate liquid, separate solid and liquid, and remove metal elements to obtain a third intermediate liquid;

The third intermediate liquid is subjected to chemical oxygen demand reduction treatment to remove organic matter to obtain a second intermediate liquid.

Optionally, the steps of adding alkali liquid to the first intermediate liquid, separating solid and liquid, removing metal elements, and obtaining the third intermediate liquid include:

Add alkali liquid to the first intermediate liquid, adjust the pH value to 9-10, precipitate the metal elements in the first intermediate liquid, and separate the solid and liquid to obtain the third intermediate liquid.

Optionally, in the mixed liquid after mixing the first anti-iron liquid and the phosphorus-containing wastewater, the iron content is greater than the phosphorus content.

Optionally, the lithium battery recycling waste liquid includes a second antiferrous post-liquid, and the step of removing metal elements and organic matter in the first intermediate liquid to obtain the second intermediate liquid includes:

Pass the second anti-iron post liquid through an iron-removing resin exchange column to perform iron-removing treatment;

Backwash the iron-removing resin exchange column with water to obtain backwash water, merge the backwash water into the first intermediate liquid, and remove metal elements and organic matter in the first intermediate liquid and the backwash water, A second intermediate liquid is obtained.

Optionally, the step of passing the second anti-iron solution through an iron-removing resin exchange column for iron removal treatment includes:

Pass the second anti-iron-removed liquid through an iron-removing resin exchange column to perform iron-removing treatment, and collect the iron-removing filtrate;

The iron removal filtrate is configured as a stripping agent.

Optionally, the first anti-iron post-liquid includes at least one of ferric chloride and ferric sulfate, and the phosphorus-containing wastewater includes phosphate.

Optionally, the acidity of the first anti-iron solution is 4-4.5 mol/L.

Optionally, the iron content in the first anti-iron solution is 1.5-2.5g/L;

And/or, the total phosphorus content in the phosphorus-containing wastewater is 450-600 mg/L.

Optionally, the total phosphorus removal rate in the step of mixing the first anti-ferrous post liquid and the phosphorus-containing wastewater, separating the solid and liquid to obtain the first intermediate liquid is greater than 98%.

The present application provides a method for treating lithium battery recycling waste liquid. The lithium battery recycling waste liquid includes a first anti-iron back liquid and phosphorus-containing waste water. By mixing the first anti-iron back liquid and the phosphorus-containing waste water, , solid-liquid separation is performed to obtain the first intermediate liquid, which achieves the purpose of simultaneously treating the first anti-iron back liquid and the phosphorus-containing wastewater. In this way, the first anti-iron back liquid can be effectively used to remove phosphorus-containing wastewater. Phosphorus is obtained to obtain a first intermediate liquid in which phosphorus is removed, and then a second intermediate liquid is obtained by removing metal elements and organic matter in the first intermediate liquid, thereby achieving the removal of metal elements and organic matter, and removing the third intermediate liquid of metal elements and organic matter. The second intermediate liquid is a salt solution, so the finished salt and condensed water can be obtained by evaporating and crystallizing the second intermediate liquid. The finished salt can be produced as a by-product, and the condensed water obtained by evaporation can be recycled, thus achieving zero waste water. emissions purposes. In this way, on the one hand, the impact of wastewater containing salts, heavy metals, and organic matter on the environment can be effectively reduced; on the other hand, since the first anti-iron backwater and phosphorus-containing wastewater are both waste liquids generated during the recycling process of lithium batteries, Utilizing the mutual reaction between waste liquids, the treatment reagents required for waste liquid treatment of the two waste liquids can be saved at the same time, effectively reducing the cost of wastewater treatment. Therefore, the treatment methods for phosphorus-containing wastewater include chemical methods, biological methods, coagulation flotation methods, physical and chemical methods, etc. These methods all require the addition of phosphorus removal agents to the phosphorus-containing wastewater. The phosphorus-containing wastewater produced by waste battery recycling enterprises every year The wastewater amounts to hundreds of tons, and the required phosphorus removal agent costs millions. The technical drawback of high wastewater treatment costs can achieve the purpose of cost reduction and zero discharge at the same time.

Description of the drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description, serve to explain the principles of the application.

In order to more clearly explain the embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to describe the embodiments or the prior art. Obviously, for those of ordinary skill in the art, It is said that other drawings can also be obtained based on these drawings without exerting creative labor.

Figure 1 is a schematic flow chart of an embodiment of the lithium battery recycling waste liquid treatment method of the present application.

The realization of the purpose, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings.

Detailed ways

In order to make the above objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without any creative work shall fall within the scope of protection of the present invention.

The embodiment of the present application provides a lithium battery recycling waste liquid treatment method. Referring to Figure 1, the lithium battery recycling waste liquid includes the first anti-iron back liquid and phosphorus-containing waste water. The lithium battery recycling waste liquid treatment method includes the following steps :

Step S10, mix the first anti-iron post liquid and the phosphorus-containing wastewater, and separate the solid and liquid to obtain the first intermediate liquid;

In this embodiment, it should be noted that lithium precipitation, internal short circuit, separator corrosion, electrode material crushing, electrolyte dissolution, etc. may cause the lithium battery to fail after its service life or during use. For effective recycling, just stacking and placing will cause solid waste pollution. What's more serious is that the large amount of valuable metals in the lithium battery electrode materials will cause acidification or alkalization of the soil in the area. If it migrates for a long time, it will It pollutes groundwater and causes the deterioration of water bodies. Since lithium batteries contain a certain amount of organic solvents, acidic gases or greenhouse gases will be produced when left for a long time, causing the air in the area to be polluted and ultimately posing a threat to human health. Therefore, the recycling of used lithium batteries has attracted widespread attention. In the process of recycling used lithium batteries, the liquid phase will inevitably be introduced during the recycling of different components, so waste liquid will inevitably be produced. Direct discharge of these waste liquids will also cause environmental pollution and ultimately endanger human health, so waste liquid treatment is required. The lithium battery recycling waste liquid refers to the waste liquid produced in the process of recycling used lithium batteries. The lithium battery recycling waste liquid includes anti-iron back liquid and phosphorus-containing wastewater, wherein the anti-iron back liquid refers to the aqueous phase containing iron ions that is stripped out from the extraction agent, and the extraction agent is used for valuable In the process of metal extraction, iron is often extracted into the extraction agent, and then a back-extraction agent needs to be added to back-extract the extraction agent to separate the iron in the extraction agent from the extraction agent. After separation, the iron enters the water phase. That is the anti-iron back liquid. The anti-iron back liquid can be discharged after meeting the discharge requirements through waste liquid treatment, and the organic phase with iron impurities removed can further extract valuable metals; the phosphorus-containing wastewater refers to the recycling of used lithium batteries The waste liquid containing phosphorus elements generated during the process can be discharged after meeting the discharge requirements through waste liquid treatment.

Optionally, the first anti-iron post-liquid includes at least one of ferric chloride and ferric sulfate, and the phosphorus-containing wastewater includes phosphate.

In this embodiment, different stripping agents are used for back-extraction, and the forms of iron in the back-iron solution are different. Iron and phosphorus have better flocculation effect under acidic conditions. Therefore, acid can be used for back-extraction, for example , you can use hydrochloric acid for back extraction, and the formed anti-iron back liquid contains ferric chloride, or you can use sulfuric acid for back extraction, and the formed anti iron back liquid contains iron sulfate, which can save the need to adjust the pH value. of acid.

Optionally, the acidity of the first anti-iron solution is 4-4.5 mol/L.

In this embodiment, the flocculation effect of iron and phosphorus is better under acidic conditions, so the acidity of the first anti-iron solution is determined to be 4-4.5 mol/L, such as 4 mol/L, 4.2 mol/L, 4.5 mol/L etc.

Optionally, the iron content in the first anti-iron solution is 1.5-2.5g/L;

And/or, the total phosphorus content in the phosphorus-containing wastewater is 450-600 mg/L.

In this embodiment, the iron content in the first anti-iron solution is 1.5-2.5g/L, such as 1.5g/L, 2.0g/L, 2.5g/L, etc. The total phosphorus content in the phosphorus-containing wastewater is 450-600 mg/L, such as 450 mg/L, 500 mg/L, 550 mg/L, 600 mg/L, etc.

Optionally, in the mixed liquid after mixing the first anti-iron liquid and the phosphorus-containing wastewater, the iron content is greater than the phosphorus content.

In this embodiment, it should be noted that after the first anti-iron back liquid and the phosphorus-containing wastewater are mixed, the iron ions in the first anti-iron back liquid and the phosphate radicals in the phosphorus-containing wastewater The ions react at a ratio of 1:1 to form flocs. After solid-liquid separation, iron ions and phosphate ions can be removed simultaneously. However, the iron ions themselves will also undergo a flocculation reaction with water, consuming part of the iron. On the one hand , the amount of anti-iron liquid produced during the recycling process of used lithium batteries is relatively large, usually more than the amount of phosphorus-containing wastewater produced. Therefore, an excess of anti-iron liquid is easy to achieve. On the other hand, a slight excess The iron can be removed together with the subsequent precipitation and removal of metal elements. Therefore, excess anti-iron liquid will not add additional processes. Therefore, the added amounts of the first anti-iron back liquid and the phosphorus-containing wastewater should be such that the iron content in the mixed liquid after the first anti-iron back liquid and the phosphorus-containing wastewater are mixed is greater than the phosphorus content, This ensures that phosphorus is fully removed, and excess iron can be removed together with metal elements or through resin alone. The details can be determined according to the actual situation, which is not limited in this embodiment.

Exemplarily, the step S10 includes: mixing the first anti-ferrous liquid and the phosphorus-containing wastewater, so that the iron in the first anti-ferrous liquid and the phosphorus in the phosphorus-containing wastewater undergo a flocculation reaction. , thereby separating the phosphorus in the phosphorus-containing wastewater and the iron in the first anti-iron solution from the liquid phase to form flocs, and then perform solid-liquid separation to remove the phosphorus in the liquid phase and obtain a relatively high phosphorus content. Low first intermediate liquid. The addition amounts of the first anti-iron liquid and the phosphorus-containing wastewater can be determined according to actual conditions, and are not limited in this embodiment.

Optionally, the total phosphorus removal rate in the step of mixing the first anti-ferrous post liquid and the phosphorus-containing wastewater, separating the solid and liquid to obtain the first intermediate liquid is greater than 98%.

In this embodiment, the first anti-iron post liquid mixed with the phosphorus-containing wastewater has a better phosphorus removal effect, and can remove more than 98% of the total phosphorus in the phosphorus-containing wastewater.

Step S20, remove metal elements and organic matter in the first intermediate liquid to obtain a second intermediate liquid;

Exemplarily, the step S20 includes: removing the metal elements in the first intermediate liquid through chemical precipitation, membrane separation, adsorption, ion exchange and other methods, and then removing the metal elements from the first intermediate liquid through oxidation, reverse osmosis, etc. The organic matter in the first intermediate liquid is removed by methods such as flocculation precipitation method and electrolysis method to obtain a second intermediate liquid with lower heavy metal content and lower COD.

Optionally, the step of removing metal elements and organic matter in the first intermediate liquid to obtain the second intermediate liquid includes:

Step A10: Add alkali liquid to the first intermediate liquid, separate the solid and liquid, and remove metal elements to obtain a third intermediate liquid;

Step A20: perform chemical oxygen demand reduction treatment on the third intermediate liquid, remove organic matter, and obtain a second intermediate liquid.

Exemplarily, the steps A10-A20 include: adding alkali liquid to the first intermediate liquid, adjusting the pH value of the first intermediate liquid, and as the pH value increases, the metal in the first intermediate liquid The elements gradually precipitate and separate, and the solid-liquid separation can be used to obtain a third intermediate liquid after removing the metal elements, and then the first intermediate liquid can be removed through oxidation, reverse osmosis, flocculation and precipitation, electrolysis and other methods. organic matter to reduce the chemical oxygen demand in the third intermediate liquid and obtain a second intermediate liquid with lower heavy metal content and lower COD.

Optionally, the steps of adding alkali liquid to the first intermediate liquid, separating solid and liquid, removing metal elements, and obtaining the third intermediate liquid include:

Add alkali liquid to the first intermediate liquid, adjust the pH value to 9-10, precipitate the metal elements in the first intermediate liquid, and separate the solid and liquid to obtain the third intermediate liquid.

For example, alkali solution can be added to the first intermediate liquid to adjust the pH value of the first intermediate liquid. As the pH value increases, the metal elements in the first intermediate liquid gradually precipitate out until When the pH value reaches 9-10, stop adding the alkali solution, so that the metal elements in the first intermediate solution can fully react under the conditions of pH value 9-10. After complete precipitation, solid-liquid separation is performed to obtain the solution after removing the metal elements. The third intermediate liquid.

In an implementable manner, alkali solution is added to the first intermediate solution to adjust the pH value to 9.5.

In this embodiment, an alkali solution is added to the first intermediate liquid, adjusted to different pH values, and metal elements are precipitated. The remaining metal elements in the third intermediate liquid obtained after solid-liquid separation are detected, and the detection results are obtained. As shown in Table 1:

Table 1

It can be seen from Table 1 that when alkali solution is added to the first intermediate liquid and the pH value is adjusted to above 9.5, the precipitation effect of the metal elements in the first intermediate liquid is better. In this case, the solid-liquid separation obtained There are fewer metal elements remaining in the third intermediate liquid.

In addition, since the third intermediate liquid needs to be further processed to reduce chemical oxygen demand, the COD (Chemical Oxygen Demand) of the second intermediate liquid obtained by reducing the chemical oxygen demand of the third intermediate liquid with different pH values is Oxygen content) was tested, and the test results are shown in Table 2:

Table 2

pH 7 8 9 9.5 10 COD-sample 1(mg/L) 719.5 482.1 320.7 117.8 246.4 COD-sample 2(mg/L) 703.6 456.3 311.5 108.8 256.7

It can be seen from Table 2 that when the pH value of the third intermediate solution is 9.5, the effect of chemical oxygen demand reduction treatment is better, and COD can be reduced to less than 120 mg/L.

Optionally, the lithium battery recycling waste liquid includes a second antiferrous post-liquid, and the step of removing metal elements and organic matter in the first intermediate liquid to obtain the second intermediate liquid includes:

Step B10, pass the second anti-iron solution through an iron-removing resin exchange column to perform iron-removing treatment;

Step B20, backwash the iron removal resin exchange column with water to obtain backwash water, merge the backwash water into the first intermediate liquid, and remove the metal elements in the first intermediate liquid and the backwash water. and organic matter to obtain a second intermediate liquid.

In this embodiment, it should be noted that the amount of anti-iron liquid produced during the recycling process of used lithium batteries is larger, usually more than the amount of phosphorus-containing wastewater produced. In the process of reaction with phosphorus-containing wastewater In the process, a slight excess of anti-iron post-fluid can ensure sufficient removal of phosphorus. However, too much anti-ferric post-fluid will increase the pressure of subsequent removal of metal elements, increase the amount of reagents required for subsequent removal of metal elements, increase costs, and may affect Therefore, the slightly excessive amount of the first anti-iron liquid can be determined in advance based on the phosphorus content in the phosphorus-containing wastewater and the iron content in the anti-iron liquid. The back liquid, that is, the second anti-iron back liquid, is processed separately through an iron removal resin exchange column.

Exemplarily, the steps B10-B20 include: adding the second anti-iron back liquid into an iron removal resin exchange column, adsorbing the iron in the second anti-iron back liquid through the iron removal resin exchange column, and the filtrate If the impurity content is small, it can be recycled or processed into by-products, and then pure water is added to the iron-removing resin exchange column, the iron-removing resin exchange column is backwashed, the outflowing backwash water is collected, and the backwash water is Incorporate into the first intermediate liquid, and perform subsequent treatment together with the first intermediate liquid to achieve zero wastewater discharge.

Optionally, the step of passing the second anti-iron solution through an iron-removing resin exchange column for iron removal treatment includes:

Step B11, pass the second anti-iron-removed liquid through an iron-removing resin exchange column for iron-removing treatment, and collect the iron-removing filtrate;

Step B12, configure the iron removal filtrate into a stripping agent.

Exemplarily, the steps B11-B12 include: adding the second anti-iron back liquid into an iron removal resin exchange column, adsorbing the iron in the second anti-iron back liquid through the iron removal resin exchange column, and collecting the removed iron. The main component of the iron filtrate and the iron-removing filtrate is the stripping agent added when stripping the iron in the extraction liquid. Therefore, the iron-removing filtrate can be used to configure the stripping agent. For example, when hydrochloric acid is used to back-extract the iron in P204, the iron-removing filtrate is a hydrochloric acid solution. The collected iron-removing filtrate can be sent to the acid solution preparation workshop, configured into a hydrochloric acid solution, and used again for reaction. extraction. In this way, not only can zero discharge of waste liquid be achieved, but the use of stripping agents can also be reduced, and the amount of alkali added when removing metal elements can also be reduced.

Step S30: The second intermediate liquid is evaporated and crystallized to obtain finished salt and condensed water.

Exemplarily, the step S30 includes: the second intermediate liquid after removing metal elements and organic matter is mainly a salt solution, such as sodium chloride solution, so the finished salt and condensed water can be obtained by evaporation and crystallization, wherein the finished salt It can be sold as a by-product, and the condensed water can be recycled. No waste liquid is produced in the whole process, so the purpose of zero discharge of waste liquid is achieved.

In this embodiment, by mixing the first anti-iron back liquid and the phosphorus-containing wastewater and separating the solid and liquid to obtain the first intermediate liquid, it is possible to simultaneously process the first anti-iron back liquid and the phosphorus-containing wastewater. For the purpose of treating wastewater, in this way, the first anti-iron back liquid can be effectively used to remove phosphorus in phosphorus-containing wastewater, and a first intermediate liquid that removes phosphorus can be obtained, and further by removing metal elements and organic matter in the first intermediate liquid, Obtaining the second intermediate liquid realizes the removal of metal elements and organic matter. The second intermediate liquid with the metal elements and organic matter removed is a salt solution. Therefore, the finished salt and condensed water can be obtained by evaporating and crystallizing the second intermediate liquid. The finished salt can be produced as a by-product, and the condensed water obtained by evaporation can be recycled, thus achieving zero wastewater discharge. In this way, on the one hand, the impact of wastewater containing salts, heavy metals, and organic matter on the environment can be effectively reduced; on the other hand, since the first anti-iron backwater and phosphorus-containing wastewater are both waste liquids generated during the recycling process of lithium batteries, Utilizing the mutual reaction between waste liquids, the treatment reagents required for waste liquid treatment of the two waste liquids can be saved at the same time, effectively reducing the cost of wastewater treatment. Therefore, the treatment methods for phosphorus-containing wastewater include chemical methods, biological methods, coagulation flotation methods, physical and chemical methods, etc. These methods all require the addition of phosphorus removal agents to the phosphorus-containing wastewater. The phosphorus-containing wastewater produced by waste battery recycling enterprises every year The wastewater amounts to hundreds of tons, and the required phosphorus removal agent costs millions. The technical drawback of high wastewater treatment costs can achieve the purpose of cost reduction and zero discharge at the same time.

In fact, taking the annual output of 5,000 tons of ferric phosphate as an example, the excess antiferric acid in this process is used to prepare 4N hydrochloric acid, which reduces the purchase of hydrochloric acid at a cost of about 3 million yuan/year; it also reduces the acid content in wastewater and reduces the use of liquid alkali. , the cost is about 1.5 million yuan/a; the condensate water recovered by evaporation and crystallization is reused about 19,800 m ³ /year, and the cost is about 1.6 million yuan/year; the total cost saving is 6 million yuan/year, and the cost of producing 1 ton of iron phosphate can be saved by 1,200 yuan Yuan. It can be seen that this application can effectively reduce production costs and is of great economic significance.

Further, in order to further understand the present application, the oil removal process of the extracted product liquid provided by the present application will be described in detail below in conjunction with the examples. The examples of the present invention all use commercially available raw materials.

Example 1

A battery recycling company uses hydrochloric acid to back-extract the iron in P204 and P507, and collects the first anti-iron liquid. The main component of the first anti-iron liquid is FeCl ₃ , and the acidity of the residual acid is about 4mol/L. The iron content is about 2g/L. Collect phosphorus-containing wastewater, wherein the total phosphorus content in the phosphorus-containing wastewater is 527.6 mg/L, the COD content is 800 mg/L, and the pH value of the wastewater is 2.5.

Mix the first anti-iron post liquid and the phosphorus-containing wastewater in a ratio of 2.06:1, and separate the solid and liquid to obtain the first intermediate liquid;

Add 30% sodium hydroxide to the first intermediate liquid to adjust the pH value to 9.5. After solid-liquid separation, perform chemical oxygen demand reduction treatment to obtain a second intermediate liquid;

The second intermediate liquid is added to an MVR (mechanical vapor recompression) evaporator for evaporation and crystallization to obtain finished salt and condensed water.

After testing, the total phosphorus content in the first intermediate liquid was 6.8 mg/L, and the total phosphorus removal rate reached 98.7%; the contents of nickel, copper, zinc, and iron in the second intermediate liquid were all less than the detection limit. Metal elements are effectively removed; the COD content in the second intermediate liquid is 108.8 mg/L, and the COD is greatly reduced.

Example 2

A battery recycling company uses hydrochloric acid to back-extract the iron in P204 and P507, and collects the first anti-iron liquid. The main component of the first anti-iron liquid is FeCl ₃ , and the acidity of the residual acid is about 4.5 mol/L. , the iron content is about 1.5g/L. Collect phosphorus-containing wastewater, wherein the total phosphorus content in the phosphorus-containing wastewater is 546.3 mg/L, the COD content is 800 mg/L, and the pH value of the wastewater is 2.

Mix the first anti-iron post liquid and the phosphorus-containing wastewater in a ratio of 2.5:1, and separate the solid and liquid to obtain the first intermediate liquid;

Add 30% sodium hydroxide to the first intermediate liquid to adjust the pH value to 9. After solid-liquid separation, perform chemical oxygen demand reduction treatment to obtain a second intermediate liquid;

The second intermediate liquid is added to the MVR evaporator for evaporation and crystallization to obtain finished salt and condensed water.

After testing, the total phosphorus content in the first intermediate liquid was 9.2 mg/L, and the total phosphorus removal rate reached 98.3%; the contents of nickel, copper, zinc, and iron in the second intermediate liquid were all less than the detection limit. Metal elements are effectively removed; the COD content in the second intermediate liquid is 196.1 mg/L, and the COD is greatly reduced.

Example 3

A battery recycling company uses hydrochloric acid to back-extract the iron in P204 and P507, and collects the first anti-iron liquid. The main component of the first anti-iron liquid is FeCl ₃ , and the acidity of the residual acid is about 4.2mol/L. , the iron content is about 2.5g/L. Collect phosphorus-containing wastewater, wherein the total phosphorus content in the phosphorus-containing wastewater is 502.5 mg/L, the COD content is 800 mg/L, and the pH value of the wastewater is 2.

Mix the first anti-iron post liquid and the phosphorus-containing wastewater in a ratio of 2:1, and separate the solid and liquid to obtain the first intermediate liquid;

Add 30% sodium hydroxide to the first intermediate liquid, adjust the pH value to 10, and after solid-liquid separation, perform chemical oxygen demand reduction treatment to obtain a second intermediate liquid;

The second intermediate liquid is added to the MVR evaporator for evaporation and crystallization to obtain finished salt and condensed water.

After testing, the total phosphorus content in the first intermediate liquid was 7.1 mg/L, and the total phosphorus removal rate reached 98.6%; the contents of nickel, copper, zinc, and iron in the second intermediate liquid were all less than the detection limit. Metal elements are effectively removed; the COD content in the second intermediate liquid is 178.2 mg/L, and the COD is greatly reduced.

The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the description of the present application, or directly or indirectly applied in other related technical fields, shall be regarded as the same. The treatment is included in the patent processing scope of this application.

Claims (10)

1. A lithium battery recycling waste liquid treatment method, characterized in that the lithium battery recycling waste liquid includes the first anti-iron back liquid and phosphorus-containing waste water, and the lithium battery recycling waste liquid treatment method includes the following steps: Mix the first anti-iron post liquid and the phosphorus-containing wastewater, and separate the solid and liquid to obtain a first intermediate liquid; Remove metal elements and organic matter in the first intermediate liquid to obtain a second intermediate liquid; The second intermediate liquid is evaporated and crystallized to obtain finished salt and condensed water. 2. The lithium battery recycling waste liquid treatment method according to claim 1, characterized in that the step of removing metal elements and organic matter in the first intermediate liquid to obtain the second intermediate liquid includes: Add alkali liquid to the first intermediate liquid, separate solid and liquid, and remove metal elements to obtain a third intermediate liquid; The third intermediate liquid is subjected to chemical oxygen demand reduction treatment to remove organic matter to obtain a second intermediate liquid. 3. The lithium battery recycling waste liquid treatment method according to claim 2, characterized in that the step of adding alkali liquid to the first intermediate liquid, solid-liquid separation, removing metal elements, and obtaining a third intermediate liquid include: Add alkali liquid to the first intermediate liquid, adjust the pH value to 9-10, precipitate the metal elements in the first intermediate liquid, and separate the solid and liquid to obtain the third intermediate liquid. 4. The lithium battery recycling waste liquid treatment method according to claim 1, characterized in that, in the mixed liquid after mixing the first anti-iron liquid and the phosphorus-containing wastewater, the iron content is greater than the phosphorus content. 5. The lithium battery recycling waste liquid treatment method as claimed in claim 1, characterized in that, the lithium battery recycling waste liquid includes a second anti-iron back liquid, and the metal elements and metal elements in the first intermediate liquid are removed. Organic matter, the steps to obtain the second intermediate liquid include: Pass the second anti-iron post liquid through an iron-removing resin exchange column to perform iron-removing treatment; Backwash the iron-removing resin exchange column with water to obtain backwash water, merge the backwash water into the first intermediate liquid, and remove metal elements and organic matter in the first intermediate liquid and the backwash water, A second intermediate liquid is obtained. 6. The lithium battery recycling waste liquid treatment method according to claim 5, wherein the step of passing the second anti-iron post liquid through an iron removal resin exchange column for iron removal treatment includes: Pass the second anti-iron-removed liquid through an iron-removing resin exchange column to perform iron-removing treatment, and collect the iron-removing filtrate; The iron removal filtrate is configured as a stripping agent. 7. The lithium battery recycling waste liquid treatment method as claimed in claim 1, characterized in that the first anti-iron back liquid includes at least one of ferric chloride and ferric sulfate, and the phosphorus-containing wastewater includes phosphate. . 8. The lithium battery recycling waste liquid treatment method according to claim 6, characterized in that the acidity of the first anti-iron post-liquid is 4-4.5 mol/L. 9. The lithium battery recycling waste liquid treatment method according to claim 1, wherein the iron content in the first anti-iron liquid is 1.5-2.5g/L; And/or, the total phosphorus content in the phosphorus-containing wastewater is 450-600 mg/L. 10. The lithium battery recycling waste liquid treatment method according to any one of claims 1 to 9, characterized in that the first anti-iron back liquid is mixed with the phosphorus-containing waste water, and solid-liquid separation is carried out. The total phosphorus removal rate of the step of obtaining the first intermediate liquid is greater than 98%.