Ternary precursor washing water treatment method and system

Abstract

The invention discloses a method for treating ternary precursor washing water, comprising the following steps: (1) pre-treating the ternary precursor washing water; (2) passing the pre-treated ternary precursor washing water into an ultrafiltration membrane filtration system; (3) the liquid filtered by the ultrafiltration membrane filtration system enters a reverse osmosis membrane system, the concentrated water obtained by the reverse osmosis membrane system is passed into an evaporation system for concentration and evaporation, and the clear liquid obtained by filtering the reverse osmosis membrane system is passed into an EDI system. The invention also discloses a treatment system for the above-mentioned ternary precursor washing water treatment method.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and in particular to a method and system for treating ternary precursor washing water. Background Art

[0002] Ternary material [LiNixCoyMn1-x-yO2] is one of the most promising positive electrode materials for power lithium batteries. The current international mainstream nickel-cobalt-manganese ternary precursor production adopts the hydroxide co-precipitation process.

[0003] Sulfate and sodium ions are the most common impurities in the coprecipitation process for preparing nickel-cobalt-manganese ternary precursors. They are also the two most common ion forms in the ternary wash water. In addition, lithium, nickel, cobalt, manganese and other cations are also present, and some may also contain a certain amount of ammonium. The existing technology for treating ternary precursor wash water is difficult and costly. Summary of the Invention

[0004] The main purpose of the present invention is to provide a ternary precursor water washing treatment method and system to solve the problem of poor ternary precursor water washing treatment effect in the prior art.

[0005] In order to achieve the above object, according to one aspect of the present invention, a ternary precursor washing water treatment method is provided, comprising the following steps:

[0006] (1) pre-treating the ternary precursor by washing water;

[0007] (2) passing the pretreated ternary precursor washing water into the ultrafiltration membrane filtration system;

[0008] (3) The liquid filtered through the ultrafiltration membrane filtration system enters the reverse osmosis membrane system. The concentrated water obtained by the reverse osmosis membrane system is passed into the evaporation system for concentration and evaporation. The clear liquid obtained by the reverse osmosis membrane system is passed into the EDI system.

[0009] Furthermore, step (1) is specifically to place the ternary precursor washing water into a pH regulating tank, the pH of which is 9-11, and is first pretreated to reduce it to 6-8, and then cooled by a heat exchange system.

[0010] Furthermore, the ultrafiltration membrane filtration system filters out particles with a molecular weight greater than 500 and a particle diameter greater than 10 nm.

[0011] Furthermore, step (3) is specifically as follows: the liquid obtained by filtration through the ultrafiltration membrane filtration system enters the first-stage reverse osmosis membrane unit for concentration, and the concentrated water obtained enters the MVR evaporation system. The MVR evaporation system evaporates the concentrated water to realize lithium salt recovery. The clear liquid obtained by the first-stage reverse osmosis membrane unit and the condensed water obtained during the evaporation process of the MVR evaporation system enter the second-stage reverse osmosis membrane unit and are filtered in the second-stage reverse osmosis membrane unit. The concentrated liquid obtained by the second-stage reverse osmosis membrane unit is returned to the first-stage reverse osmosis membrane unit for circulation treatment. The produced water obtained by filtration of the second-stage reverse osmosis membrane unit continues to enter the third-stage reverse osmosis membrane unit. The produced water obtained by filtration of the third-stage reverse osmosis membrane unit enters the EDI system to obtain ultrapure water. The concentrated liquid obtained by the third-stage reverse osmosis membrane unit is returned to the second-stage reverse osmosis membrane unit for circulation treatment. The concentrated water obtained by the EDI system is returned to the third-stage reverse osmosis membrane unit for circulation treatment.

[0012] In order to achieve the above-mentioned purpose, according to another aspect of the present invention, a ternary precursor washing water treatment system is also provided, which includes a pretreatment system, a heat exchange system, an ultrafiltration membrane filtration system, a reverse osmosis membrane system, an evaporation system connected to the concentrated liquid outlet of the reverse osmosis membrane system, and an EDI system connected to the clear liquid outlet of the reverse osmosis membrane system.

[0013] Furthermore, the pretreatment system includes a pH adjustment tank and a heat exchanger connected to the pH adjustment tank.

[0014] Furthermore, the ultrafiltration membrane filtration system is a membrane filtration system that filters out particles with a molecular weight greater than 500 and a particle diameter greater than 10 nm.

[0015] Furthermore, the reverse osmosis membrane system includes a first-stage reverse osmosis membrane unit, a second-stage reverse osmosis membrane unit, and a third-stage reverse osmosis membrane unit connected in sequence, wherein the concentrated water outlet of the first-stage reverse osmosis membrane unit is connected to the evaporation system, the clear liquid outlet of each stage of the reverse osmosis membrane unit is connected to the liquid inlet of the next stage of the reverse osmosis membrane unit, and the concentrated liquid outlet of each stage of the reverse osmosis membrane unit is connected to the liquid inlet of the previous stage of the reverse osmosis membrane unit.

[0016] Furthermore, the EDI system is an EDI system that reduces the conductivity of the clear liquid obtained from the reverse osmosis membrane system to below 5 μS / cm.

[0017] Furthermore, the evaporation system is an MVR evaporation system.

[0018] It can be seen that the advantages of the treatment method and system for ternary precursor washing water of the present invention are: the use of this process enables the precursor production process to achieve zero wastewater discharge; the use of a membrane system to concentrate the raw liquid greatly reduces the MVR processing volume, which is conducive to reducing the processing difficulty and saving processing costs; reducing energy consumption and having obvious environmental benefits; the system is easy to control and simple to operate; through the combined process of the membrane treatment system and the EDI system, the water quality of the produced water reaches the standard of ultrapure water, which generates direct economic benefits and effectively avoids the waste of a large amount of water resources.

[0019] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Additional aspects and advantages of the present invention will be partially given in the following description, partially become apparent from the following description, or be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings that constitute part of this invention are intended to assist in understanding the invention. The contents provided in the drawings and their related descriptions in the present invention may be used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0021] Figure 1 This is a flow chart of the ternary precursor water washing treatment process equipment of the present invention. DETAILED DESCRIPTION

[0022] The present invention is described clearly and completely below with reference to the accompanying drawings. A person skilled in the art will be able to implement the present invention based on these descriptions. Before describing the present invention with reference to the accompanying drawings, it should be noted that:

[0023] The technical solutions and technical features provided in each part of the present invention, including the following description, may be combined with each other unless there is any conflict.

[0024] In addition, the embodiments of the present invention described below are generally only partial embodiments of the present invention, rather than all embodiments. Therefore, all other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.

[0025] Regarding the terms and units in the present invention: The terms "include", "have" and any variations thereof in the description and claims of the present invention and the related parts are intended to cover non-exclusive inclusions.

[0026] The term "EDI system" in the present invention refers to EDI pure water equipment including EDI technology, which is a pure water manufacturing technology that combines ion exchange technology, ion exchange membrane technology and ion electromigration technology.

[0027] In order to achieve the above object, according to one aspect of the present invention, a ternary precursor washing water treatment method is provided, comprising the following steps:

[0028] (1) pre-treating the ternary precursor by washing water;

[0029] (2) passing the pretreated ternary precursor washing water into the ultrafiltration membrane filtration system;

[0030] (3) The liquid filtered through the ultrafiltration membrane filtration system enters the reverse osmosis membrane system. The concentrated water obtained by the reverse osmosis membrane system is passed into the evaporation system for concentration and evaporation. The clear liquid obtained by the reverse osmosis membrane system is passed into the EDI system.

[0031] Furthermore, step (1) is specifically to place the ternary precursor washing water into a pH regulating tank, the pH of which is 9-11, and is first pretreated to reduce it to 6-8, and then cooled by a heat exchange system.

[0032] Furthermore, the ultrafiltration membrane filtration system filters out particles with a molecular weight greater than 500 and a particle diameter greater than 10 nm.

[0033] Furthermore, step (3) is specifically as follows: the liquid obtained by filtration through the ultrafiltration membrane filtration system enters the first-stage reverse osmosis membrane unit for concentration, and the concentrated water obtained enters the MVR evaporation system. The MVR evaporation system evaporates the concentrated water to realize lithium salt recovery. The clear liquid obtained by the first-stage reverse osmosis membrane unit and the condensed water obtained during the evaporation process of the MVR evaporation system enter the second-stage reverse osmosis membrane unit and are filtered in the second-stage reverse osmosis membrane unit. The concentrated liquid obtained by the second-stage reverse osmosis membrane unit is returned to the first-stage reverse osmosis membrane unit for circulation treatment. The produced water obtained by filtration of the second-stage reverse osmosis membrane unit continues to enter the third-stage reverse osmosis membrane unit. The produced water obtained by filtration of the third-stage reverse osmosis membrane unit enters the EDI system to obtain ultrapure water. The concentrated liquid obtained by the third-stage reverse osmosis membrane unit is returned to the second-stage reverse osmosis membrane unit for circulation treatment. The concentrated water obtained by the EDI system is returned to the third-stage reverse osmosis membrane unit for circulation treatment.

[0034] In order to achieve the above-mentioned purpose, according to another aspect of the present invention, a ternary precursor washing water treatment system is also provided, which includes a pretreatment system, a heat exchange system, an ultrafiltration membrane filtration system, a reverse osmosis membrane system, an evaporation system connected to the concentrated liquid outlet of the reverse osmosis membrane system, and an EDI system connected to the clear liquid outlet of the reverse osmosis membrane system.

[0035] Furthermore, the pretreatment system includes a pH adjustment tank and a heat exchanger connected to the pH adjustment tank.

[0036] Furthermore, the ultrafiltration membrane filtration system is a membrane filtration system that filters out particles with a molecular weight greater than 500 and a particle diameter greater than 10 nm.

[0037] Furthermore, the reverse osmosis membrane system includes a first-stage reverse osmosis membrane unit, a second-stage reverse osmosis membrane unit, and a third-stage reverse osmosis membrane unit connected in sequence, wherein the concentrated water outlet of the first-stage reverse osmosis membrane unit is connected to the evaporation system, the clear liquid outlet of each stage of the reverse osmosis membrane unit is connected to the liquid inlet of the next stage of the reverse osmosis membrane unit, and the concentrated liquid outlet of each stage of the reverse osmosis membrane unit is connected to the liquid inlet of the previous stage of the reverse osmosis membrane unit.

[0038] Furthermore, the EDI system is an EDI system that reduces the conductivity of the clear liquid obtained from the reverse osmosis membrane system to below 5 μS / cm.

[0039] Furthermore, the evaporation system is an MVR evaporation system.

[0040] It can be seen that the advantages of the treatment method and system for ternary precursor washing water of the present invention are: the use of this process enables the precursor production process to achieve zero wastewater discharge; the use of a membrane system to concentrate the raw liquid greatly reduces the MVR processing volume, which is conducive to reducing the processing difficulty and saving processing costs; reducing energy consumption and having obvious environmental benefits; the system is easy to control and simple to operate; through the combined process of the membrane treatment system and the EDI system, the water quality of the produced water reaches the standard of ultrapure water, which generates direct economic benefits and effectively avoids the waste of a large amount of water resources.

[0041] The ternary precursor washing water is placed in a pH adjustment tank. The pH of the ternary precursor washing water is 9-11. It is first pre-treated to reduce it to 6-8. After passing through a heat exchange system, the ternary precursor washing water is placed in an ultrafiltration membrane filtration system. The ultrafiltration membrane filtration system filters out particles with a molecular weight greater than 500 and a particle diameter greater than 10 nm.

[0042] The liquid filtered through the ultrafiltration membrane filtration system enters the primary reverse osmosis membrane unit, and the concentrated water obtained by the primary reverse osmosis membrane unit enters the MVR evaporation system. The MVR evaporation system evaporates the concentrated water to recover lithium salts. The clear liquid obtained from the primary reverse osmosis membrane unit and the condensed water obtained during the evaporation process of the MVR evaporation system enter the secondary reverse osmosis membrane unit and are filtered in the secondary reverse osmosis membrane unit. The concentrated liquid obtained by the secondary reverse osmosis membrane unit is returned to the primary reverse osmosis membrane unit for circulation treatment. The produced water obtained by filtration of the secondary reverse osmosis membrane unit continues to enter the tertiary reverse osmosis membrane unit. The produced water obtained by filtration of the tertiary reverse osmosis membrane unit enters the EDI system to obtain ultrapure water. The concentrated liquid obtained by the tertiary reverse osmosis membrane unit is returned to the secondary reverse osmosis membrane unit for circulation treatment. The concentrated water obtained by the EDI system is returned to the tertiary reverse osmosis membrane unit for circulation treatment.

[0043] In the above steps:

[0044] The pH of the ternary wash water with a pH of 9-11 is first reduced to 6-8 by pretreatment, firstly to meet the membrane feeding requirements, and secondly to convert the ammonia nitrogen in it into ammonium ions with a higher interception rate;

[0045] The heat exchange system uses a heat exchanger to reduce the wastewater temperature (preferably 20-40°C) and regulate the heat release during the pH reduction reaction process;

[0046] Among them, the ultrafiltration membrane filtration system further removes large particles in the liquid and reduces turbidity. The ultrafiltration membrane filtration system is a membrane filtration system that filters out particles with a molecular weight greater than 500 and a particle diameter greater than 10nm. Among them, the reverse osmosis membrane system concentrates and separates the solution, and the produced water can meet the reuse standards. The produced water continues to use EDI technology to reduce the conductivity to below 5μS / cm.

[0047] like Figure 1 As shown, the present invention also relates to a ternary precursor washing water treatment system, which includes a pretreatment system, a heat exchange system, an ultrafiltration membrane filtration system 3, a reverse osmosis membrane system, an evaporation system 5 connected to the concentrated liquid outlet of the reverse osmosis membrane system, and an EDI system 8 connected to the clear liquid outlet of the reverse osmosis membrane system.

[0048] The pretreatment system includes a pH adjustment tank 1 and a heat exchanger 2 connected to the pH adjustment tank 1 .

[0049] The ultrafiltration membrane filtration system 3 is a membrane filtration system that filters out particles with a molecular weight greater than 500 and a particle diameter greater than 10 nm.

[0050] The reverse osmosis membrane system includes a first-stage reverse osmosis membrane unit 4, a second-stage reverse osmosis membrane unit 6, and a third-stage reverse osmosis membrane unit 7 connected in sequence, wherein the concentrated water outlet of the first-stage reverse osmosis membrane unit is connected to the evaporation system, the clear liquid outlet of each stage of the reverse osmosis membrane unit is connected to the liquid inlet of the next stage of the reverse osmosis membrane unit, and the concentrated liquid outlet of each stage of the reverse osmosis membrane unit is connected to the liquid inlet of the previous stage of the reverse osmosis membrane unit.

[0051] The EDI system 8 is an EDI system that reduces the conductivity of the clear liquid obtained from the reverse osmosis membrane system to below 5 μS / cm.

[0052] The above describes the relevant contents of the present invention. Based on this description, a person skilled in the art will be able to implement the present invention. Based on the above contents of the present invention, all other embodiments obtained by a person skilled in the art without making any creative efforts should fall within the scope of protection of the present invention.

Claims

1. A ternary precursor washing water treatment method, comprising the following steps: (1) pre-treating the ternary precursor washing water; (2) passing the pre-treated ternary precursor washing water into an ultrafiltration membrane filtration system; (3) The liquid obtained by filtration through the ultrafiltration membrane filtration system enters the reverse osmosis membrane system, and the concentrated water obtained by the reverse osmosis membrane system is passed into the evaporation system for concentration and evaporation, and the clear liquid obtained by filtration through the reverse osmosis membrane system is passed into the EDI system; Step (1) is specifically placed in a pH adjustment tank, the pH of the ternary precursor washing water is 9-11, first pre-treated to reduce it to 6-8, and then cooled by a heat exchange system; the ultrafiltration membrane filtration system filters out particles with a molecular weight greater than 500 and a particle diameter greater than 10nm; Step (3) is specifically the liquid obtained by filtration through the ultrafiltration membrane filtration system enters the primary reverse osmosis membrane unit, and the concentrated water obtained by concentration enters the MVR evaporation system, and the MVR The evaporation system evaporates the concentrated water to recover lithium salts. The clear liquid obtained from the primary reverse osmosis membrane unit and the condensed water obtained during the evaporation process of the MVR evaporation system enter the secondary reverse osmosis membrane unit and are filtered in the secondary reverse osmosis membrane unit. The concentrated liquid obtained by concentration in the secondary reverse osmosis membrane unit is returned to the primary reverse osmosis membrane unit for circulation treatment. The produced water obtained by filtration in the secondary reverse osmosis membrane unit continues to enter the tertiary reverse osmosis membrane unit. The produced water obtained by filtration in the tertiary reverse osmosis membrane unit enters the EDI system to obtain ultrapure water. The concentrated liquid obtained by concentration in the tertiary reverse osmosis membrane unit is returned to the secondary reverse osmosis membrane unit for circulation treatment. The concentrated water obtained in the EDI system is returned to the tertiary reverse osmosis membrane unit for circulation treatment.

2. The ternary precursor washing water treatment system is characterized by: A ternary precursor washing water treatment method for claim 1; the system comprises a pretreatment system, a heat exchange system, an ultrafiltration membrane filtration system, a reverse osmosis membrane system, an evaporation system (5) connected to a concentrated liquid outlet of the reverse osmosis membrane system, and an EDI system connected to a clear liquid outlet of the reverse osmosis membrane system, which are connected in sequence; the pretreatment system comprises a pH adjustment tank (1) and a heat exchanger (2) connected to the pH adjustment tank (1); the ultrafiltration membrane filtration system (3) is a membrane filtration system for filtering out particles with a molecular weight greater than 500 and a particle diameter greater than 10 nm; the reverse osmosis membrane system comprises a primary reverse osmosis membrane unit (4), a secondary reverse osmosis membrane unit (6), and a tertiary reverse osmosis membrane unit (7) connected in sequence, wherein the concentrated water outlet of the primary reverse osmosis membrane unit (4) is connected to the evaporation system (5), the clear liquid outlet of each reverse osmosis membrane unit is connected to a liquid inlet of a next reverse osmosis membrane unit, and the concentrated liquid outlet of each reverse osmosis membrane unit is connected to a liquid inlet of a previous reverse osmosis membrane unit.

3. The ternary precursor washing water treatment system according to claim 2, characterized in that: The EDI system (8) is an EDI system for reducing the conductivity of the clear liquid obtained from the reverse osmosis membrane system to below 5 μS / cm.

4. The ternary precursor washing water treatment system according to claim 2, characterized in that: The evaporation system (5) is an MVR evaporation system.

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