KR20210080078A - Treatment method of wastewater of spent lithium ion battery - Google Patents

Abstract

The present invention provides a method for treating wastewater of a waste lithium secondary battery. The method for treating wastewater of a waste lithium secondary battery according to an embodiment of the present invention includes the steps of: leaching a positive electrode material of a waste lithium secondary battery with an acid to manufacture a leachate; adjusting the pH of the leachate with an alkaline substance; separating valuable metals and wastewater from the pH-adjusted leachate; and recovering lithium and acid through bipolar electrodialysis of the wastewater.

Description

Wastewater treatment method of waste lithium ion battery {TREATMENT METHOD OF WASTEWATER OF SPENT LITHIUM ION BATTERY}

The present invention relates to a wastewater treatment method of a waste lithium-ion battery. More specifically, it relates to a method for efficiently treating wastewater generated after recovering valuable metals from a waste lithium-ion battery.

As the demand for eco-friendly technologies such as electric vehicles and energy storage as well as portable batteries increases, the demand for lithium-ion batteries is rapidly increasing.

The lifespan of lithium-ion batteries varies from several days to several decades, depending on the type, charge/discharge cycle, and usage environment.

Waste lithium-ion batteries at the end of their lifespan can cause environmental problems when buried, and contain expensive metals such as cobalt, nickel, manganese, and lithium. Therefore, the environmental load is reduced and valuable metals are recovered through recycling, but cobalt, nickel, manganese, etc., which are expensive and have a large content, are mainly recovered.

In general, the wet method is mainly used to recover valuable metals from waste lithium-ion batteries. After separating the cathode material powder from the disassembled battery, it is leached into metal ions with sulfuric acid, and then through precipitation using alkali, solvent extraction, etc. Sulfates or hydroxides of cobalt, nickel and manganese are obtained.

When cobalt, nickel, and manganese are recovered in this way, a large amount of wastewater is inevitably generated, and the wastewater mainly contains lithium, sodium, and sulfate ions. Wastewater contains a large amount of salts, so treatment is required for discharge, and lithium is one of the main raw materials for battery manufacturing, and its recovery technology is required.

The present invention provides a method for treating wastewater of a waste lithium-ion battery. More specifically, there is provided a method for efficiently treating wastewater generated after recovering valuable metals from a waste lithium-ion battery.

According to an embodiment of the present invention, there is provided a method for treating wastewater of a waste lithium-ion battery, comprising the steps of: leaching a cathode material of a waste lithium-ion battery with an acid to prepare a leachate; adjusting the pH of the leachate with an alkaline substance; Separation of valuable metals and wastewater from the pH-adjusted leachate; and bipolar electrodialysis of the wastewater to recover lithium and acid.

In the step of adjusting the pH of the leachate with an alkali substance, the alkali substance may be lithium hydroxide (LiOH), lithium hydroxide monohydrate (LiOH·H ₂ O), or an aqueous solution thereof.

Lithium hydroxide, which is an alkaline material, may be in a recycled form of lithium recovered in the step of bipolar electrodialysis of wastewater to recover lithium and acid.

Lithium hydroxide, which is an alkaline material, is recycled in the step of: recovering lithium and acid by bipolar electrodialysis of wastewater; 10 to 90 wt% of 100 wt% of lithium recovered in the step of adjusting the pH of the leachate with an alkaline material; can

The method may further include: recovering lithium and acid by bipolar electrodialysis of wastewater; in the step, lithium is recovered in the form of an aqueous lithium hydroxide solution, and carbonation of the recovered lithium hydroxide aqueous solution to prepare lithium carbonate.

The method may further include a step of recovering lithium and acid by bipolar electrodialysis of wastewater; in the step, lithium is recovered in the form of an aqueous lithium hydroxide solution, and the recovered lithium hydroxide aqueous solution is concentrated to prepare solid lithium hydroxide.

The acid recovered in the bipolar electrodialysis of wastewater to recover lithium and acid may be reused as acid in the step of leaching a cathode material of a spent lithium ion battery with acid to prepare a leachate.

In the step of leaching the cathode material of the spent lithium ion battery with an acid to prepare a leachate, the acid may be sulfuric acid.

Meanwhile, in the step of adjusting the pH of the leachate with an alkali substance, the alkali substance may be sodium hydroxide (NaOH) or sodium hydroxide (NaOH) aqueous solution.

In the step of recovering lithium and acid by bipolar electrodialysis of wastewater, an aqueous sodium hydroxide solution may be recovered.

The recovered aqueous sodium hydroxide solution may be reused as an alkaline material in the step of adjusting the pH of the leachate with an alkaline material.

The wastewater treatment method of a waste lithium ion battery according to an embodiment of the present invention can reduce the environmental load by recovering resources from wastewater generated while recovering valuable metals from the waste lithium ion battery, and minimizing the amount of wastewater generated.

In the wastewater treatment method of a waste lithium ion battery according to an embodiment of the present invention, lithium in wastewater can be recovered and acid and alkali solutions can be prepared, and the prepared acid and alkali solutions are cobalt, nickel, It can be used as a raw material to recover valuable metals such as manganese. That is, it can be recycled.

Lithium carbonate may be prepared by injecting carbonate ions into the alkali solution prepared in the wastewater treatment method of a spent lithium ion battery according to an embodiment of the present invention, or lithium hydroxide or lithium hydroxide monohydrate may be prepared by evaporation.

1 is a schematic process diagram of Example 1 of the present invention.
2 is a schematic process diagram of Example 2 of the present invention.

In this specification, terms such as first, second and third are used to describe, but are not limited to, various parts, components, regions, layers and/or sections. These terms are used only to distinguish one part, component, region, layer or section from another part, component, region, layer or section. Accordingly, a first part, component, region, layer or section described below may be referred to as a second part, component, region, layer or section without departing from the scope of the present invention.

In the present specification, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components unless otherwise stated.

In this specification, the terminology used is for the purpose of referring to specific embodiments only, and is not intended to limit the present invention. As used herein, the singular forms also include the plural forms unless the phrases clearly indicate the opposite. The meaning of "comprising," as used herein, specifies a particular characteristic, region, integer, step, operation, element and/or component, and includes the presence or absence of another characteristic, region, integer, step, operation, element and/or component. It does not exclude additions.

In the present specification, the term "combination of these" included in the expression of the Markush form means one or more mixtures or combinations selected from the group consisting of the components described in the expression of the Markush form, and the components It means to include one or more selected from the group consisting of.

In this specification, when a part is referred to as being “on” or “on” another part, it may be directly on or on the other part, or the other part may be accompanied in between. In contrast, when a part refers to being "directly above" another part, the other part is not interposed therebetween.

Although not defined otherwise, all terms including technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Commonly used terms defined in the dictionary are additionally interpreted as having a meaning consistent with the related technical literature and the presently disclosed content, and unless defined, they are not interpreted in an ideal or very formal meaning.

In addition, unless otherwise specified, % means weight %, and 1 ppm is 0.0001 weight %.

In an embodiment of the present invention, the meaning of further including the additional element means that the remaining iron (Fe) is included by replacing the additional amount of the additional element.

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein.

According to an embodiment of the present invention, there is provided a method for treating wastewater of a waste lithium-ion battery, comprising the steps of: leaching a cathode material of a waste lithium-ion battery with an acid to prepare a leachate; adjusting the pH of the leachate with an alkaline substance; Separation of valuable metals and wastewater from the pH-adjusted leachate; and bipolar electrodialysis of the wastewater to recover lithium and acid.

The following describes each step.

First, a leachate is prepared by leaching a cathode material of a spent lithium ion battery with an acid.

The acid in this step may be a strong acid, more specifically sulfuric acid.

Elements leached in this step may include cobalt, nickel, manganese, lithium, or a combination thereof.

Thereafter, the leachate is pH-adjusted with an alkaline substance.

The alkali material in this step may include lithium hydroxide (LiOH), and more specifically, lithium hydroxide (LiOH), lithium hydroxide monohydrate (LiOH·H ₂ O), or an aqueous solution thereof.

In this case, lithium hydroxide (LiOH), lithium hydroxide monohydrate (LiOH·H ₂ O), or an aqueous solution thereof, which is an alkaline material, is subjected to bipolar electrodialysis of wastewater to recover lithium and acid; lithium recovered in the recycling process may be in the form

In addition, lithium hydroxide (LiOH), lithium hydroxide monohydrate (LiOH·H ₂ O), or an aqueous solution thereof, which is an alkaline material, is obtained by bipolar electrodialysis of wastewater to recover lithium and acid; lithium recovered in 100 weight 10 to 90% by weight of the % may be recycled by adjusting the pH of the leachate with an alkaline substance. More specifically, 30 to 80% by weight may be recycled in the step of adjusting the pH of the leachate with an alkaline material. If the amount of recovered lithium recycled to the step of adjusting the pH is large, the process cost increases, and if it is small, the process cost may be lowered.

Meanwhile, the alkali material in this step may be sodium hydroxide (NaOH) or sodium hydroxide (NaOH) aqueous solution.

Thereafter, the pH-adjusted leachate is separated into valuable metals and wastewater.

In this step, a leachate obtained by leaching cobalt, nickel, manganese, lithium, etc. by reacting a cathode material of a spent lithium ion battery with an acid may be recovered as a valuable metal by precipitation, solvent extraction, or the like. The wastewater generated after the valuable metal is recovered is mainly Na ⁺ , Li ⁺ , SO ₄ ^-2 ions, and trace amounts of other ions may exist.

In this case, the Li ⁺ concentration in the wastewater containing lithium may be 1.5 g/L or more.

Thereafter, the wastewater is subjected to bipolar electrodialysis to recover lithium and acid.

More specifically, this step may be to separate ^{Na +} , Li ⁺ and SO ₄ ^{-2 by bipolar electrodialysis of wastewater.} Bipolar electrodialysis generates OH ^- and H ⁺ , and Na ⁺ , Li ⁺ moves to a chamber in which ^{OH -} _{is produced, and SO 4} ^-2 moves to a chamber in which H ⁺ is produced. So NaOH, LiOH aqueous solution and H ₂ SO ₄ solutions can be prepared. At this time, the efficiency of bipolar electrodialysis can be increased by diluting the wastewater, concentrating, or pretreatment such as ion exchange.

Alkali and acidic solutions can be prepared by electrodialysis of wastewater as described above, which is an acid and alkali raw material such as a precipitant used for leaching, pH adjustment, or recovery of salts of cobalt, nickel, and manganese when treating a waste lithium ion battery can be used as At this time, the acid or alkali concentration may be increased by evaporating the solution.

In the wastewater, the main ions Na ⁺ , Li ⁺ , and SO ₄ ^-2 were mostly moved to the chamber where the NaOH, LiOH, H ₂ SO ₄ solution was produced by bipolar electrodialysis, so the next leachate was prepared with a very low electrolyte concentration. It can be used as water for bipolar electrodialysis. In addition, it is possible to prepare a solution in which the electrolyte concentration is further lowered by electrodialysis.

First, in the step of recovering lithium and acid by bipolar electrodialysis of wastewater; an aqueous solution of sodium hydroxide (NaOH) or an aqueous solution of lithium hydroxide (LiOH) may be recovered. In this case, the recovered sodium hydroxide (NaOH) aqueous solution or lithium hydroxide (LiOH) aqueous solution may be reused as an alkaline material in the step of adjusting the pH of the leachate with an alkaline material. In particular, when lithium hydroxide (LiOH), lithium hydroxide monohydrate (LiOH·H ₂ O), or an aqueous solution thereof, which is an alkaline material, bipolar electrodialysis of wastewater to recover lithium and acid; lithium recovered in the recycling process may be in the form

The method may further include a step of carbonating the recovered lithium hydroxide (LiOH) aqueous solution to prepare lithium carbonate. Lithium carbonate may be prepared by adding carbonate ions such as _{CO 2} (g) or Na ₂ CO ₃ in NaOH or LiOH aqueous solution.

The method may further include a step of concentrating the recovered lithium hydroxide (LiOH) aqueous solution to prepare solid lithium hydroxide.

_{That is, lithium carbonate can be prepared by adding carbonate ions such as CO 2} (g) or Na ₂ CO _{3 to an} aqueous solution of NaOH or LiOH prepared by electrodialysis, and when concentrated, lithium hydroxide (or monohydrate) can be obtained. have. In the case of lithium carbonate, since the solubility of _{Na 2} CO ₃ or NaHCO _{3 is higher than that of Li 2} CO ₃ or LiHCO ₃ , Na ions do not precipitate, so that lithium carbonate with high purity can be manufactured. As a method of increasing the recovery rate of lithium carbonate, there is a method of increasing the reaction temperature or evaporating.

In addition, the acid recovered in the bipolar electrodialysis of wastewater to recover lithium and acid may be reused as an acid in the step of preparing a leachate by leaching a cathode material of a spent lithium ion battery with acid.

On the other hand, when valuable metals such as cobalt, nickel, manganese, etc. are recovered by precipitation or solvent extraction by leaching a spent lithium ion battery with sulfuric acid, an alkali material such as NaOH may be used as a pH control or precipitating agent. When LiOH or LiOH·H ₂ O is used as an alkali material or an aqueous solution thereof is used, valuable metals such as cobalt, nickel, and manganese are recovered from the leachate and the resulting wastewater is mainly composed of Li ⁺ , SO ₄ ^-2 , and bipolar. By electrodialysis, a high concentration of LiOH aqueous solution and H ₂ SO ₄ solution can be prepared. This can be carbonated to obtain lithium carbonate.

Meanwhile, before the step of bipolar electrodialysis of the wastewater to recover lithium and acid, the wastewater to be used may be diluted or pretreated by concentration, ion exchange, or the like.

Hereinafter, the present invention will be described in more detail through examples. However, these examples are only for illustrating the present invention, and the present invention is not limited thereto.

Example

[Example 1]

1. Separation of wastewater

Valuable metals such as cobalt, nickel, and manganese are recovered using powder such as anode material separated from a waste lithium-ion battery as a raw material, and the resulting wastewater is generally generated through the following process.

First, a powder such as a cathode material is reacted with an inorganic acid such as sulfuric acid to be leached. At this time, various impurities including valuable metals such as cobalt, nickel, manganese, and lithium are ionized and present in the solution.

Thereafter, the leachate is separated using an acid/alkali substance to adjust its pH, or valuable metals such as cobalt, nickel, and manganese are separated from the leachate in the form of sulfate or hydroxide by solvent extraction or precipitation.

In Example 1 of the present invention, NaOH was used as an alkali material for adjusting pH.

After the above processes, valuable metals such as cobalt, nickel, and manganese are recovered from the leachate and the remaining wastewater is generated, and the chemical composition is shown in Table 1. That is, Table 1 below means the composition of wastewater generated during recycling of the waste lithium ion battery, and the unit of concentration of each element is g/L.

sample Li SO ₄ Ca Na K wastewater 2.35 69.08 0.02 21.18 0.04

2. Lithium recovery from wastewater

The solution was introduced into a bipolar electrodialysis machine.

Table 2 below shows the ion concentration of each solution after bipolar electrodialysis of wastewater as a result. In this case, the concentration unit of each element is g/L.

Looking at the results in Table 2, the Li ⁺ concentration of demineralized water, which is wastewater, was lowered to 0.21 _{g/L, SO 4} ^-2 was 3.51 g/L, and Na ⁺ was lowered to 0.31 g/L, etc. Total ions analyzed in wastewater Silver can be removed from 90.32 g/L to 4.03 g/L at the initial stage, and more than 95.5% can be removed.

The main ion concentration of the base chamber is 5.35 g/L ^{for Li + and 69.17 g/L for Na +} , so it can be confirmed that LiOH and NaOH aqueous solution is prepared, and SO ₄ ^-2 concentration of the acid chamber about 12% of sulfuric acid was prepared at 119.32 g/L.

These results indicate that alkali and acid solutions can be effectively prepared by bipolar electrodialysis of wastewater.

sample Li SO ₄ Ca Na K Demineralized water 0.21 3.51 - 0.31 - Base chamber 5.35 2.00 0.04 69.17 0.11 Acid chamber 0.10 119.32 0.02 1.06 -

1 shows a schematic process diagram of Example 1 when NaOH was used as an alkali raw material. Sulfuric acid and NaOH separated by bipolar electrodialysis can be recycled, and the separated lithium hydroxide can be carbonated to lithium carbonate and crystallized to obtain solid lithium hydroxide.

[Example 2]

1. Separation of wastewater

_{LiOH·H 2} O was used instead of NaOH as an alkali raw material used for pH control and precipitation when recovering valuable metals such as cobalt, nickel, and manganese using powder such as anode material separated from a waste lithium ion battery as a raw material.

Other experimental procedures were the same as in Example 1.

The chemical composition of the wastewater generated at this time is shown in Table 3. The concentration unit of each raw material at this time is g/L.

^{The Li +} concentration of the generated wastewater was increased, and the Na ⁺ concentration was 0.10 g/L, which was very low.

sample Li SO ₄ Ca Na K wastewater 8.74 69.08 0.02 0.10 0.04

2. Lithium recovery from wastewater

The solution was introduced into a bipolar electrodialysis machine.

Table 4 below shows the ion concentration of each solution after bipolar electrodialysis of wastewater as a result. In this case, the unit of concentration of each element is g/L.

^{The Li +} concentration of the demineralized wastewater was reduced to 0.78 g/L, SO ₄ ^-2 was 3.53 g/L, and other ions were not detected. The analyzed total ions of wastewater can be removed from the initial 78.00g/L to 4.31g/L, and more than 94.5% can be removed.

The concentration of Li ^{+ in the} base chamber is 19.90 g/L, and the concentration of Na ⁺ is 0.32 g/L, so it can be seen that an aqueous LiOH solution is mainly prepared, and SO ₄ ^-2 in the acid chamber is 119.5 g/L. about 12% sulfuric acid was prepared.

In particular, since an aqueous LiOH solution with a low Na content is prepared in the base chamber, high-purity lithium carbonate can be produced by supplying carbonate ions, and high-purity lithium hydroxide (or monohydrate) can be produced by concentration. .

sample Li SO ₄ Ca Na K Demineralized water 0.78 3.53 - - - Base chamber 19.9 2.00 0.04 0.32 0.10 Acid chamber 0.37 119.50 0.02 0.01 -

2 shows a schematic process diagram of Example 2 when LiOH was used as an alkali raw material. Sulfuric acid and LiOH separated by bipolar electrodialysis can be recycled (recycled), and the separated lithium hydroxide can be carbonated to lithium carbonate, and crystallized to obtain solid lithium hydroxide.

At this time, the recovered lithium was recycled in the step of adjusting the pH of the leachate with an alkaline material. The recycled amount was 10 to 90% by weight.

Table 5 shows the effect of lithium recovery rate according to the amount of recovered lithium (lithium hydroxide) recycled to the pH control step. According to the results of Table 5, when the recycled amount was 30 to 80 wt%, the lithium recovery rate was 50 wt% or more.

Amount of recycled lithium lithium recovery rate 10% by weight 45% by weight 30% by weight 55% by weight 70% by weight 95% by weight 80% by weight 69% by weight 90% by weight 33% by weight

The present invention is not limited to the embodiments, but may be manufactured in various different forms, and those of ordinary skill in the art to which the present invention pertains may develop other specific forms without changing the technical spirit or essential features of the present invention. It will be appreciated that this may be practiced. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

Claims (11)

leaching a cathode material of a spent lithium-ion battery with an acid to prepare a leachate;
adjusting the pH of the leachate with an alkaline substance;
separating valuable metals and wastewater from the pH-adjusted leachate; and
bipolar electrodialysis of the wastewater to recover lithium and acid;
A wastewater treatment method of a waste lithium-ion battery comprising a.
According to claim 1,
In the step of adjusting the pH of the leachate with an alkali material;
The alkali material is lithium hydroxide (LiOH), lithium hydroxide monohydrate (LiOH · H ₂ O), or an aqueous solution thereof.
3. The method of claim 2,
Lithium hydroxide (LiOH), lithium hydroxide monohydrate (LiOH · H ₂ O), or an aqueous solution thereof, which is the alkali material,
Recovering lithium and acid by bipolar electrodialysis of the wastewater; a wastewater treatment method of a waste lithium-ion battery in which the lithium recovered in the process is in a recycled form.
4. The method of claim 3,
Lithium hydroxide (LiOH), lithium hydroxide monohydrate (LiOH · H ₂ O), or an aqueous solution thereof, which is the alkali material,
Bipolar electrodialysis of the wastewater to recover lithium and acid; 10 to 90% by weight of 100% by weight of lithium recovered in the step of adjusting the pH of the leachate with an alkaline substance; Wastewater treatment method.
According to claim 1,
Recovering lithium and acid by bipolar electrodialysis of the wastewater;
The lithium is recovered in the form of an aqueous lithium hydroxide solution,
Carbonating the recovered lithium hydroxide aqueous solution to produce lithium carbonate; Wastewater treatment method of a waste lithium ion battery further comprising a.
According to claim 1,
Recovering lithium and acid by bipolar electrodialysis of the wastewater;
The lithium is recovered in the form of an aqueous lithium hydroxide solution,
Concentrating the recovered lithium hydroxide aqueous solution to prepare solid lithium hydroxide; wastewater treatment method of a waste lithium ion battery further comprising a.
According to claim 1,
recovering lithium and acid by bipolar electrodialysis of the wastewater;
leaching the cathode material of the waste lithium ion battery with an acid to prepare a leachate; a method for treating wastewater of a waste lithium ion battery in which the acid is reused.
According to claim 1,
leaching the cathode material of the spent lithium ion battery with an acid to prepare a leachate; in,
The method for treating wastewater of a waste lithium ion battery is that the acid is sulfuric acid.
According to claim 1,
In the step of adjusting the pH of the leachate with an alkali material;
The alkali material is sodium hydroxide (NaOH) or sodium hydroxide (NaOH) aqueous solution of a wastewater treatment method of a waste lithium ion battery.
According to claim 1,
Recovering lithium and acid by bipolar electrodialysis of the wastewater;
A wastewater treatment method of a waste lithium ion battery in which the sodium hydroxide aqueous solution is recovered.
11. The method of claim 10,
The recovered aqueous sodium hydroxide solution,
A method for treating wastewater of a waste lithium ion battery, wherein the leachate is reused as an alkali material in the step of adjusting the pH with an alkali material.

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