KR20140009048A - Method of recovering lithium from fly ashes or waste water derived from active material for lithium secondary battery by using electrochemisty process - Google Patents

Abstract

The present invention provides a method for collecting lithium from fly ashes or waste water caused in the production process of active materials for a lithium secondary battery using an electrochemical method. The method comprises the steps of: preparing fly ash water or waste water caused in the production process of active materials for a lithium secondary battery (S10); manufacturing lithium manganese oxide by putting a sorbent into the fly ash water or the waste water caused in the production process of the active materials for a lithium secondary battery (S20); manufacturing slurry by stirring after putting the lithium manganese oxide, a conductive material, a binder, and a solvent into a stirrer (S30); coating the manufactured slurry on aluminum foil or copper foil and drying the coated slurry (S40); checking the reactive potential with a cyclic voltammetry after the slurry-coated aluminum foil or copper foil is put into an electrolytic cell containing an electrode plate and lithium metal (S50); depositing the lithium on the surface of the electrode plate by maintaining the electrolytic cell as the checked reactive potential (S60); and separating the lithium deposited on the surface of the electrode plate (S70). [Reference numerals] (AA) START; (BB) END; (S10) Prepare fly ash water or waste water caused in the production process of active materials for a lithium secondary battery; (S20) Manufacture lithium manganese oxide by putting a sorbent into the fly ash water or the waste water caused in the production process of the active materials for a lithium secondary battery; (S30) Manufacture slurry by stirring a stirrer after the lithium manganese oxide, a conductive material, a binder, and a solvent are put into the stirrer; (S40) Dry the manufactured slurry after the manufactured slurry is coated with aluminum foil or copper foil; (S50) check the reactive potential with a cyclic voltammetry after the slurry-coated aluminum foil or copper foil is put into an electrolytic cell containing an electrode plate and lithium metal; (S60) Deposit lithium on the surface of the electrode plate by maintaining the electrolytic cell as the checked reactive potential; (S70) Separate the lithium deposited on the surface of the electrode plate

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for recovering lithium from wastewater generated in a production process of a fly ash or an active material for a lithium secondary battery by using an electrochemical method. BACKGROUND ART [0002]

The present invention relates to a method for recovering lithium from wastewater generated in a production process of fly ash or a lithium secondary battery active material by using an electrochemical method, and more particularly, to a method for recovering lithium from wastewater that can be recycled for waste, And a method for recovering lithium from fly ash using a chemical method.

Fly ashes are fine particles that are rapidly cooled by the ash in coal when the coal is burned in the furnace at high temperature inside the furnace. Since fly ash belongs to waste and is highly radioactive, conventionally it has been common to fill fly ash in the ground. However, in order to dispose of coal ash, it is costly and environmental pollution problem occurs. Recently, various studies on the recycling of fly ash have been carried out.

Since the fly ash is a by-product generated after burning coal, the fly ash contains a lot of rare metals. In particular, since about 1 kg of fly ash contains about 850 mg of lithium carbonate, fly ash has a higher lithium concentration than seawater having a lithium content of about 0.17 mg per liter.

Lithium is the lightest metal distributed in the world in small amounts. It is used in lithium secondary batteries, ceramic electronic materials, refrigerant adsorbents, and medicines using lithium isotopes. Due to power generation, the use of lithium secondary batteries has exploded. Currently, the lithium secondary battery industry is centered on Korea, Japan and China, and the consumption of lithium, which is a core raw material, is rapidly increasing due to the rapidly increasing demand of lithium secondary batteries. In addition, since lithium is used to multiply tritium in fusion power generation, which is expected to be the next generation energy source, the demand for lithium is further increased.

Lithium is recovered by ion exchange adsorption, solvent extraction, and coprecipitation using seawater. Among these trials, lithium ion recovery using manganese oxide-based inorganic adsorbents with ion exchange properties with very high selectivity This is mainly used.

However, in the process of recovering lithium from the lithium-adsorbed manganese oxide, conventionally, a method of recovering lithium by desorbing lithium ions by treating an adsorbent to which lithium ions are adsorbed with an acid aqueous solution is used. This conventional lithium recovery method has a problem that the separation and drying process of the liquid obtained after the desorption process of lithium ions is added, the process is complicated, the lithium recovery time is long, and the lithium recovery rate is low.

Accordingly, the present inventors have developed a method of recovering lithium from fly ash using an electrochemical process which is simple in process, can be recycled to waste, and has excellent lithium recovery rate.

In addition, water generated or remained while producing the cathode active material for a lithium secondary battery is abandoned as wastewater. The wastewater contains about 400 ppm of lithium ions. Therefore, the inventor of the present invention has found that a method of recovering lithium from fly ash can be applied to the above-mentioned wastewater, and the present invention has developed a method of recovering lithium from wastewater in a process for producing an active material for a lithium secondary battery.

An object of the present invention is to provide a method of recovering lithium from wastewater generated in a production process of fly ash or a lithium secondary battery using an electrochemical process that is simple in process and can be recycled to waste.

Another object of the present invention is to provide a method for recovering lithium from wastewater generated in the production process of a fly ash or a lithium secondary battery active material by using an electrochemical method having an excellent lithium recovery rate.

The above and other objects of the present invention can be achieved by the present invention described below.

A method of recovering lithium from wastewater generated in a production process of a fly ash or a lithium secondary battery by using the electrochemical method according to the present invention includes the steps of preparing wastewater generated in the process of recovering coal or producing an active material for a lithium secondary battery S10); (S20) a step of preparing lithium manganese oxide by injecting an adsorbent into wastewater generated in the production process of the coal recovery or the lithium secondary battery active material; Injecting the lithium manganese oxide, the conductive material, the binder and the solvent in a stirrer to prepare a slurry (S30); Coating the slurry on the aluminum foil or copper foil, and drying the coated slurry (S40); Inserting the slurry-coated aluminum foil or copper foil into an electrolytic bath having an electrode plate and a lithium metal, and confirming a reaction potential by a cyclic voltammetric method (S50); Maintaining an electrolytic cell at the identified reaction potential to deposit lithium on the surface of the electrode plate (S60); And separating the lithium deposited on the surface of the electrode plate (S70).

Here, the coal recovery in the step S10 is characterized in that the coal recovered from the coal plant or the coal storage site or the coal recovered by mixing the fly ash with water is stirred. Further, the wastewater generated in the production process of the active material for a lithium secondary battery is generated in a process for producing a negative electrode or a positive electrode active material for a lithium secondary battery and is characterized by containing lithium ions.

The lithium manganese oxide in step S20 is represented by the following formula (1).

[Formula 1]

Li _x M _y Mn _z O ₄

Wherein M = Ge, Al, B, Ti, V, Cr, Fe, Co, Ni, Cu, Zr, Nb, Mo, Si, Mg or Zn, 1≤x≤2, 0≤y≤0.5 And 1 ≦ z ≦ 2)

The lithium manganese oxide is characterized by having a spinel structure or a pseudo spinel structure.

Wherein the lithium manganese oxide is selected from the group consisting of Li _1.6 Mn _1.6 O ₄ , Li _1.33 Mn _1.67 O ₄ , Li ₂ MnO ₃ , Li _1.6 Al _0.08 Mn _1.52 O ₄ , Li _1.6 Co _0.08 Mn _1.52 O ₄ , Li _1.6 Ti _0.08 Mn _1.52 O ₄ , Li _1.6 B _0.08 Mn _1.52 O ₄ , Li _1.6 Ge _0.08 Mn _1.52 O ₄ , Li _1.6 V _0.08 Mn _1.52 O _4, or Li _1.6 Si _0.08 Mn _1.52 O ₄ .

The conductive material is characterized in that the carbon black.

The binder is characterized in that the polyvinylidene fluoride or carboxymethyl cellulose.

The solvent is characterized by consisting of N-methyl-2-pyrrolidone or water.

The step S30 is characterized in that 25 to 35 parts by weight of the conductive material, and 10 to 20 parts by weight of the binder to 100 parts by weight of the lithium manganese oxide in a stirrer.

In addition, the step S30 is characterized in that the lithium manganese oxide, the conductive material, the binder and the solvent is stirred for 3 hours using a mixer to prepare a slurry.

In the step S40, the coated slurry is dried at 60 ± 5 ° C for 30 minutes using a dry oven, and further dried at 80 ± 5 ° C for 12 to 20 hours in a vacuum oven.

The steps S50, S60 and S70 are characterized in that the dry box or the glove box filled with argon gas.

The electrolyzer in the step S50 is characterized by being filled with a non-aqueous electrolyte in which the salt is dissolved.

The electrode plate of step S60 is formed of a nickel plate or a copper plate, it characterized in that the form of a grid.

The present invention provides a method for recovering lithium from wastewater generated in a production process of fly ash and a lithium secondary battery using an electrochemical process which is simple in process, can be recycled to waste, and has excellent lithium recovery rate. Effect.

1 is a flowchart schematically illustrating a method of recovering lithium from wastewater generated in a production process of fly ash or a lithium secondary battery active material by using the electrochemical method according to the present invention.
FIG. 2 is a graph showing the results of the measurement of the lithium manganese oxide using Li _1.33 Mn _1.67 O ₄ as a lithium manganese oxide in the method of recovering lithium from coal fly ash using the electrochemical method according to the present invention, The photograph of Lithium precipitated on the grid was taken (200 times) by scanning microscope (FE-SEM, Hitachi S-4800).
FIG. 3 is a graph showing the results of the case where Li _1.6 Mn _1.6 O ₄ is used as a lithium manganese oxide in the method of recovering lithium from coal fly ash using the electrochemical method according to the present invention, and when a copper plate grid is used as an electrode plate in the lithium precipitation step, The photograph of Lithium precipitated on the grid was taken (200 times) by scanning microscope (FE-SEM, Hitachi S-4800).
FIG. 4 is a graph showing the results of measurement of lithium manganese oxide using Li _1.33 Mn _1.67 O ₄ as a lithium manganese oxide in the method of recovering lithium from fly ash using the electrochemical method according to the present invention, (FE-SEM, Hitachi S-4800) (100 times) of lithium separated from the surface of the electrode plate when used as a plate.
FIG. 5 is a graph showing the relationship between the lithium manganese oxide and the lithium content of Li _1.6 Al _0.08 Mn _0.52 O ₄ in the method of recovering lithium from fly ash using the electrochemical method according to the present invention, (FE-SEM, Hitachi S-4800) (30 times) of lithium separated from the surface of the electrode plate when the electrode plate is used as the electrode plate.

The above objects, features and other advantages of the present invention will become more apparent by describing the preferred embodiments of the present invention in detail with reference to the accompanying drawings. Hereinafter, a method for recovering lithium from fly ash using an electrochemical method according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a flowchart schematically illustrating a method of recovering lithium from wastewater generated in a production process of fly ash or a lithium secondary battery active material by using the electrochemical method according to the present invention.

As shown in FIG. 1, the method for recovering lithium from wastewater generated in the production process of fly ash or lithium secondary battery active material by using the electrochemical method according to the present invention is characterized in that, in the production process of coal recovery or active material for lithium secondary battery (Step S20), and the step of preparing the lithium manganese oxide by injecting the adsorbent into the wastewater generated in the production process of the coal or the production process of the lithium secondary battery active material (step S20). The lithium manganese oxide, (Step S30) of adding a binder, a binder and a solvent to a stirrer to prepare a slurry (step S30), coating the prepared slurry on an aluminum foil or a copper foil, and drying the coated slurry Slurry-coated aluminum foil or copper foil is placed in an electrolytic cell equipped with an electrode plate and lithium metal, A step of checking the reaction potential (S50), a step of depositing lithium on the surface of the electrode plate by holding the electrolytic bath at the identified reaction potential (S60), and a step of separating lithium deposited on the surface of the electrode plate (Step S70).

Step S10 is a step of preparing wastewater generated in the production process of fly ashes water or an active material for a lithium secondary battery, and the recovering of the coal is performed by collecting coal or fly ashes discharged from a coal plant, Fly ashes water prepared by mixing with water and stirring can be used. When the fly ash is mixed with water and stirred, the weight ratio of the fly ash and water and the stirring conditions are not particularly limited. However, water is added in an amount larger than the fly ash so that the fly ash can be sufficiently dissolved in the water, .

The wastewater generated in the production process of the active material for a lithium secondary battery is generated in a process for producing a negative electrode or a positive electrode active material for a lithium secondary battery, and is characterized by containing lithium ions.

Step S20 is a step of preparing a lithium manganese oxide by adding an adsorbent to wastewater generated in the process of recovering the recovered coal or producing the active material for a lithium secondary battery, and the produced lithium manganese oxide is represented by the following formula (1).

[Formula 1]

Li _x M _y Mn _z O ₄

Wherein M = Ge, Al, B, Ti, V, Cr, Fe, Co, Ni, Cu, Zr, Nb, Mo, Si, Mg or Zn, 1≤x≤2, 0≤y≤0.5 And 1 ≦ z ≦ 2)

Most preferably, the lithium manganese oxide is Li _1.6 Mn _1.6 O ₄ , Li _1.33 Mn _1.67 O ₄ , Li ₂ MnO ₃ , Li _1.6 Al _0.08 Mn _1.52 O ₄ , Li _1.6 Co _0.08 Mn _1.52 O ₄ , Li _1.6 Ti _0.08 Mn _1.52 O ₄ , Li _1.6 B _0.08 Mn _1.52 O ₄ , Li _1.6 Ge _0.08 Mn _1.52 O ₄ , Li _1.6 V _0.08 Mn _1.52 O _4, or Li _1.6 Si _0.08 Mn _1.52 O ₄ . Therefore, the adsorbent uses a material in which lithium is removed from the lithium manganese oxide according to the above formula (1).

In step S30, lithium manganese oxide, a conductive material, a binder, and a solvent are added to a stirrer and stirred to prepare a slurry. The amount of the lithium manganese oxide, the conductive material, and the binder is 25 parts by weight of 35 to 35 parts by weight of the lithium manganese oxide. It is preferable to add 10-20 parts by weight of the binder and the binder to the stirrer. Accordingly, the lithium manganese oxide, the conductive material, the binder and the solvent, N-methyl-2-pyrrolidone (N-methyl-2-pyrrolidone) or water is added to the stirrer to prepare a slurry. The reason for slurrying using the solvent is to make it easy to fix the slurryed material to aluminum foil or copper foil, and the solvent may be smoothly operated by the blade of the mixer used in the stirring process of step S30. It is added slowly until it has a viscosity of about, it is preferable to proceed for 3 hours.

Step S40 is a step of coating the prepared slurry on an aluminum foil or a copper foil and drying the coated slurry. The prepared slurry is coated on an aluminum foil or a copper foil using a doctor blade, It is preferable that drying is carried out at 60 賊 5 캜 for 30 minutes and then at a temperature of 80 짹 5 캜 for 12 to 20 hours in a vacuum oven. The reason for drying the prepared slurry is that the lithium manganese oxide in the slurry state significantly reduces the reactivity in the electrolytic cell, and is intended to dry and remove impurities such as a solvent contained in the slurry. The reason why the drying step is carried out in two stages is that when the drying process is firstly carried out by using a dry oven, the liquid component contained in the slurry is removed to a certain extent, and when it is put into the vacuum oven, Because it is prevented from flowing down from the copper foil, and the primarily dried slurry in the dry oven is secondly completely dried in the vacuum oven.

In step S50, an aluminum foil or a copper foil coated with slurry is placed in an electrode plate and an electrolytic bath provided with lithium metal, and the reaction potential is confirmed by a cyclic voltammetric method. Place the electrode in an electrolytic cell equipped with a plate and a lithium metal, and check the reaction potential by cyclic voltammetry (CV). The step S50 is preferably performed in a state in which the electrolytic cell is filled with a non-aqueous electrolyte in which 1 mol of lithium salt is dissolved. When the electrolytic cell is provided, the slurry-coated aluminum foil or the copper foil is used as a working electrode, the electrode plate is used as a counter electrode, and the cyclic voltammetry is performed using the lithium metal as a reference electrode. the slurry-coated aluminum foil or a copper foil, an electrode plate and a three-electrode cell consisting of a lithium metal while walking down the potential of the range of 3 to 4.3 volts (V) to the electrolytic cell equipped with, cyclic voltammetry with a scan rate of 1mVs ^-1 To confirm the reaction potential. At this time, the electrode plate is formed of a nickel plate or a copper plate, and is preferably in the form of a copper grid.

The step S60 is a step of holding the electrolytic bath at the identified reaction potential to precipitate lithium on the surface of the electrode plate. When a predetermined time elapses after the reaction potential identified by the step S50 is applied to the electrolytic bath, the aluminum foil or copper The lithium component contained in the dry slurry coated on the foil is ionized and moved to the surface of the electrode plate, and then precipitates on the surface of the electrode plate.

Step S70 is a step of separating the lithium deposited on the surface of the electrode plate, if the lithium is deposited to a certain degree on the surface of the electrode plate to separate the electrode plate from the electrolytic cell and scrape off the lithium deposited on the surface of the electrode plate. At this time, it is preferable that the steps S50, S60, and S70 are performed in a glove box filled with a drier or an argon gas. In the glove box filled with a dry room or an argon gas, , High-purity lithium can be obtained.

FIG. 2 is a graph showing the relationship between the lithium manganese oxide Li _1.33 Mn _1.67 O ₄ , lithium foil used for lithium precipitation, and the copper plate grid as an electrode plate in the method of recovering lithium from coal fly ash using the electrochemical method according to the present invention FIG. 3 is a photograph showing a state in which lithium is precipitated on a copper plate grid when it is used, taken by a scanning microscope (FE-SEM, Hitachi S-4800) Li _1.6 Mn _1.6 O ₄ as a lithium manganese oxide was used as a lithium manganese oxide and a copper plate grid was used as an electrode plate in a lithium precipitation step, a state of lithium precipitation on a copper plate grid was observed with an injection microscope (FE-SEM , Hitachi S-4800).

FIG. 4 is a graph showing the results of measurement of lithium manganese oxide using Li _1.33 Mn _1.67 O ₄ as a lithium manganese oxide in the method of recovering lithium from fly ash using the electrochemical method according to the present invention, FIG. 5 is a photograph showing Lithium separated from the surface of the electrode plate when it was used as a plate (100 times) photographed with a scanning electron microscope (FE-SEM, Hitachi S-4800) Li _1.6 Al _0.08 Mn _0.52 O ₄ was used as a lithium manganese oxide in the method of recovering lithium from fly ash, aluminum foil was used for coating, and when the copper plate grid was used as an electrode plate during lithium deposition, (FE-SEM, Hitachi S-4800) (30 times).

As shown in FIGS. 2 to 5, when the electrochemical method according to the present invention is used, lithium can be recovered on a copper plate grid. The method of recovering lithium from the wastewater generated in the production process of fly ash or lithium secondary battery active material by using the electrochemical method according to the present invention has an advantage that the recovery rate of lithium is excellent and the process is simple. In addition, since the electrochemical method is used, the consumption of chemicals used for lithium recovery is low, thereby improving process efficiency and reducing process costs.

Although the preferred embodiments of the present invention have been described, the present invention is not limited to the specific embodiments described above. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the appended claims. All equivalents should be regarded as falling within the scope of the present invention.

Claims (14)

(S10) preparing wastewater generated in a production process of a coal recovery or an active material for a lithium secondary battery;
(S20) a step of preparing lithium manganese oxide by injecting an adsorbent into wastewater generated in the production process of the coal recovery or the lithium secondary battery active material;
Injecting the lithium manganese oxide, the conductive material, the binder and the solvent in a stirrer to prepare a slurry (S30);
Coating the slurry on the aluminum foil or copper foil, and drying the coated slurry (S40);
Inserting the slurry-coated aluminum foil or copper foil into an electrolytic bath having an electrode plate and a lithium metal, and confirming a reaction potential by a cyclic voltammetric method (S50);
Maintaining an electrolytic cell at the identified reaction potential to deposit lithium on the surface of the electrode plate (S60); And
Separating lithium deposited on the surface of the electrode plate (S70);
And recovering lithium from the wastewater generated in the production process of the fly ash or lithium secondary battery active material by using the electrochemical method. The method of claim 1,
Wherein the coal recovery in the step S10 is a recovery of coal discharged from a coal plant or a coal storage site, or a coal recovery in which the fly ash is mixed with water and stirred. The method of claim 1,
Wherein, in step S30, 25 to 35 parts by weight of the conductive material and 10 to 20 parts by weight of the binder are added to 100 parts by weight of the lithium manganese oxide in the agitator. The method of claim 1,
Wherein the lithium manganese oxide is represented by the following Formula 1:
[Chemical Formula 1]
Li _x M _y Mn _z O ₄
Wherein M = Ge, Al, B, Ti, V, Cr, Fe, Co, Ni, Cu, Zr, Nb, Mo, Si, Mg or Zn, 1≤x≤2, 0≤y≤0.5 And 1 ≦ z ≦ 2) 5. The method of claim 4,
Wherein the lithium manganese oxide has a spinel type or pseudo spinel type structure. 2. The method according to claim 1, wherein the lithium manganese oxide has a spinel type or pseudo spinel type structure. 5. The method of claim 4,
Wherein the lithium manganese oxide is selected from the group consisting of Li _1.6 Mn _1.6 O ₄ , Li _1.33 Mn _1.67 O ₄ , Li ₂ MnO ₃ , Li _1.6 Al _0.08 Mn _1.52 O ₄ , Li _1.6 Co _0.08 Mn _1.52 O ₄ , Li _1.6 Ti _0.08 Mn _1.52 O ₄ , Li _1.6 B _0.08 Mn _1.52 O ₄ , Li _1.6 Ge _0.08 Mn _1.52 O ₄ , Li _1.6 V _0.08 Mn _1.52 O _4, and Li _1.6 Si _0.08 Mn _1.52 O ₄ . The method of claim 1,
Wherein the conductive material is carbon black. The method of claim 1,
Wherein the binder is polyvinylidene fluoride or carboxymethylcellulose. The method of claim 1,
Wherein the solvent comprises N-methyl-2-pyrrolidone or water. The method of claim 1,
And the step S30 is performed by using a mixer for 3 hours to prepare a slurry. The method of claim 1,
Wherein the coated slurry is dried in a dry oven at 60 DEG C for 30 minutes and further dried in a vacuum oven at 80 DEG C for 12 to 20 hours. The method of claim 1,
Wherein the steps S50, S60, and S70 are performed in a glove box filled with a dry or argon gas. The method of claim 1,
Wherein the electrolytic bath of step S50 is filled with a nonaqueous electrolyte in which a lithium salt is dissolved. The method of claim 1,
Wherein the electrode plate in step S60 is formed of a nickel plate or a copper plate and is in the form of a grid.

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