KR20210066418A - Recovery system of lithium compound and recovery method of lithium compound - Google Patents

Abstract

The present invention relates to a lithium recovery system and a lithium recovery method, and more particularly, to a lithium recovery system and a lithium recovery method capable of recovering metal components from waste lithium batteries at high efficiency in an environmentally-friendly manner by using distilled water through a dry process. The present invention is eco-friendly because only distilled water is used without chemical treatment by strong acid or the like, and the steam used for heat exchange can be reused in a process of washing products obtained after firing, enabling a continuous process and improving recovery efficiency. The lithium recovery system includes a lithium transition metal storage unit, a firing chamber, a first reactor, a second reactor, an evaporator, a selective connection unit, a forced circulation evaporator, and a recirculation transfer line.

Description

Lithium recovery system and lithium recovery method

The present invention relates to a lithium recovery system and a lithium recovery method, and more particularly, a lithium recovery system and recovery method capable of environmentally-friendly and high efficiency recovery of metal components from waste lithium batteries using distilled water through a dry process is about

Lithium batteries usually contain lithium, manganese, cobalt, nickel, etc. as metal components, and accordingly, it is important to recover and recycle metal components including lithium from waste lithium batteries.

In relation to the recycling method of such a waste lithium battery, the recovery of valuable metals has been conventionally made using a wet process. In the case of such a wet process, there is a problem in that the amount of waste solution generated increases because organic substances or chemicals such as strong acids that are harmful to the environment are used, and there is a problem in that the cost for processing the waste solution is added and the production cost increases. Therefore, there is an urgent need for an alternative to a recycling method of a waste lithium battery that is environmentally friendly and has a high recovery efficiency while lowering the recovery cost.

Japanese Laid-Open Patent Publication No. 2013-001990 (published date: 2013.01.07) Japanese Laid-Open Patent Publication No. 2012-229481 (published date: November 22, 2012)

One object of the present invention is to provide a lithium recovery system capable of recovering metal components such as lithium from a waste lithium battery in an environmentally friendly manner and at the same time with high efficiency.

Another object of the present invention is to provide a lithium recovery method applicable to the lithium recovery system as described above.

A lithium recovery system for one purpose of the present invention includes a lithium transition metal storage unit accommodating a lithium transition metal oxide; The lithium transition metal oxide introduced from the lithium transition metal storage unit is calcined at a temperature of 600° C. to 800° C. in a reducing atmosphere under anoxic conditions _{to produce a product containing a lithium carbonate (Li 2} CO ₃ ) compound and a transition metal oxide. firing chamber; a first reactor for washing the product introduced from the calcination chamber with distilled water flowing from the distilled water storage unit _{to generate liquid lithium carbonate (Li 2} CO ₃ ) and phase-separating the solid transition metal oxide; Liquid lithium carbonate (Li ₂ CO ₃ ) introduced from the first reactor reacts with calcium hydroxide (Ca(OH) ₂ ) to produce liquid lithium hydroxide (LiOH) and solid calcium carbonate (CaCO ₃ ) reactor; and an evaporator for generating a concentrated solution obtained by evaporating and concentrating liquid lithium carbonate (Li ₂ CO ₃ ) introduced from the first reactor or liquid lithium hydroxide (LiOH) introduced from the second reactor by heat exchange with high-temperature steam; includes

The lithium recovery system according to the present invention may further include a selective connection part located at the front end of the evaporator and selectively introducing a solution discharged from either the first reactor or the second reactor into the evaporator.

The evaporator is a primary heat exchanger for first evaporating liquid lithium carbonate (Li ₂ CO ₃ ) introduced from the first reactor or liquid lithium hydroxide (LiOH) introduced from the second reactor to form a primary concentrate ; A secondary evaporator for further evaporating the primary concentrate introduced from the primary heat exchanger to form a secondary concentrate; may further include, further evaporating the secondary concentrate to form a tertiary concentrate, It may further include a forced circulation evaporator for storing the heat-exchanged steam.

The lithium recovery system according to the present invention may further include a recirculation transfer line for transferring and recirculating the vapor stored in the forced circulation evaporator to the distilled water storage unit.

The lithium recovery system according to the present invention may further include a water remover for dehydrating the tertiary concentrate introduced from the forced circulation evaporator to generate solid lithium compound crystals.

The lithium recovery system according to the present invention may sinter the lithium transition metal oxide by injecting _{carbon dioxide (CO 2 ) gas into the firing chamber.}

The lithium recovery system according to the present invention may further include a transition metal recovery chamber for recovering the transition metal powder by drying the solid transition metal oxide introduced from the first reactor.

The lithium recovery system according to the present invention may further include a calcium carbonate recovery chamber for recovering the calcium carbonate powder by drying the _{solid calcium carbonate (CaCO 3 ) introduced from the second reactor.}

A method for recovering lithium carbonate for one purpose of the present invention is

1 step of calcining the lithium transition metal oxide at a temperature of 600° C. to 800° C. in a reducing atmosphere under anoxic conditions _{to produce a product including a lithium carbonate (Li 2} CO ₃ ) compound and a transition metal oxide; A second step of always washing the product with distilled water to generate liquid lithium carbonate (Li ₂ CO ₃ ) and phase-separating the solid transition metal oxide; Step 3 of reacting the generated liquid lithium carbonate (Li ₂ CO ₃ ) with calcium hydroxide (Ca(OH) ₂ ) to produce liquid lithium hydroxide (LiOH) and solid calcium carbonate (CaCO _{3 );} and a 4 step of evaporating and concentrating the generated liquid lithium hydroxide (LiOH) by heat exchange with high-temperature steam to obtain solid lithium hydroxide.

In the method for recovering lithium carbonate according to the present invention, a continuous process may be possible by storing the vapor after heat exchange and then transferring it to be used for washing the product.

The heat exchange may be performed at least twice or more, and in order to obtain the solid lithium hydroxide, it may be dehydrated through a water remover after evaporation and concentration by heat exchange.

In the method for recovering lithium carbonate according to the present invention, carbon dioxide (CO ₂ ) gas may be injected during the sintering process to sinter the lithium transition metal oxide.

According to the lithium recovery system and lithium recovery method of the present invention, the following effects are obtained.

1. It is eco-friendly by using distilled water without chemical treatment such as strong acid through dry process, and there is no additional cost for chemical treatment, so the recovery cost can be lowered.

2. Since the steam used for heat exchange can be reused in the process of washing the product of the calcination step, a continuous process is possible, thereby improving the recovery efficiency.

3. According to the user's choice, there is an effect that the lithium metal component can be recovered in the form of lithium carbonate or lithium hydroxide.

1 is a configuration diagram showing the configuration of a lithium recovery system according to an embodiment of the present invention.
2 is a configuration diagram showing the configuration of a lithium recovery system according to another embodiment of the present invention.
3 is a conceptual diagram schematically illustrating a lithium recovery method according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to conventional or dictionary meanings, but should be interpreted as meanings and concepts consistent with the technical spirit of the present invention. Throughout this specification, when a member is said to be located “above” or “below” another member, this includes not only a case in which a member is in contact with another member but also a case in which another member is present between the two members. Throughout this 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 each step, the identification code is used for convenience of description, and the identification code does not describe the order of each step, and each step may be performed differently from the specified order unless the specific order is clearly stated in the context. have. That is, each step may be performed in the same order as specified, may be performed substantially simultaneously, or may be performed in the reverse order. In adding reference numerals to the components of each drawing, it should be noted that the same components are given the same reference numerals as much as possible even though they are indicated on different drawings. In addition, in describing the embodiment of the present invention, if it is determined that a detailed description of a related known configuration or function interferes with the understanding of the embodiment of the present invention, the detailed description thereof will be omitted. In addition, in describing the components of the embodiment of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only for distinguishing the components from other components, and the essence, order, or order of the components are not limited by the terms. When it is described that a component is “connected”, “coupled” or “connected” to another component, the component may be directly connected or connected to the other component, but another component is between each component. It will be understood that may also be "connected", "coupled" or "connected".

1 is a configuration diagram illustrating the configuration of a lithium recovery system according to an embodiment of the present invention, and FIG. 2 is a configuration diagram showing the configuration of a lithium recovery system according to another embodiment of the present invention. 1 and 2 , in order to recover lithium metal and transition metal from a waste lithium battery, etc., lithium transition metal oxide is introduced from the lithium transition metal storage unit 110 into the firing chamber 120 under anaerobic conditions. calcined in a dry process in a reducing atmosphere of

The lithium transition metal oxide may be one typically used as a cathode active material of a lithium secondary battery, and the transition metal is at least one selected from elements belonging to Groups 5 (VB) to 11 (Group VIIIB) on the periodic table. and may include nickel, cobalt, and manganese, which are typically called NCM-based, for example Li[Ni _x Co _(1-x)/2 Mn _(1-x)/2 ]O ₂ (0≤x) ≤1) may have a chemical formula, but is not necessarily limited thereto.

The dry process in the reducing atmosphere is preferably performed by receiving carbon dioxide (CO _{2 ) from the CO 2} supplier 130 , thereby forming an oxygen-free atmosphere without oxygen. In addition, a purging process may be additionally performed to completely remove oxygen from the firing chamber 120 in which the firing is performed.

Due to the injection of carbon dioxide, the firing chamber 120 can continue to maintain a reducing atmosphere, and after the firing chamber 120 is raised to at least 600°C to 800°C, it is preferable to inject it into the firing chamber in a state in which the temperature is increased. Do.

The calcination process is preferably performed at 600° C. to 800° C., and the reaction time of the calcination process may be performed for 1 to 3 hours. When the firing process is performed at a temperature of less than 600° C., the lithium transition metal oxide may not be properly fired, and when it exceeds 800° C., other by-products may be generated. When the reaction time of the calcination process is less than 1 hour, the lithium transition metal oxide may not be completely decomposed, and if the reaction time exceeds 3 hours, the effect of time on the calcination reaction is low and productivity may be reduced.

_{Lithium carbonate (Li 2} CO ₃ ) and transition metal oxide are produced as products after the calcination reaction of the lithium transition metal oxide performed in the dry process in the oxygen-free reducing atmosphere. For example, when the lithium transition metal oxide is LiNiCoMnO ₂ , the calcination reaction is as shown in Scheme 1 below, and the transition metal oxide is cobalt oxide (CoO), nickel oxide (NiO), and manganese oxide (MnO).

[Scheme 1]

LiNiCoMnO ₂ + CO ₂ (g) → Li ₂ CO ₃ + CoO + NiO + MnO + CO (g)

Next, for phase separation according to the difference in solubility of the product, the product generated in the calcination chamber is introduced into the first reactor 140 and then the product is washed with water using distilled water introduced from the distilled water storage unit 150 . do.

Lithium carbonate (Li ₂ CO ₃₎ and because the difference in solubility in water of the transition metal oxide present, the lithium carbonate from the water washing step (Li ₂ CO ₃₎ is present at the liquid lithium carbonate (Li ₂ CO ₃₎ , the transition metal oxide is present in a solid state without being dissolved, so that phase separation is possible.

The volume ratio of the product and water may be 1:1 to 1:30. In addition, the water washing process may be repeated 1 to 3 times, and the process time of one water washing process may be 30 minutes to 2 hours.

Next, for lithium reduction, the second reactor 160 _{reacts the liquid lithium carbonate (Li 2} CO ₃ ) introduced from the first reactor 140 with calcium hydroxide (Ca(OH) ₂ ) to hydrate the liquid phase. Lithium (LiOH) and solid calcium carbonate (CaCO ₃ ) are produced.

According to the user's selection, the liquid lithium carbonate (Li ₂ CO ₃ ) generated in the first reactor 140 may be introduced into the evaporator 200 to be described later without flowing into the second reactor 160 . . To this end, the selective connection unit 170 is located at the front end of the evaporator 200 , and selectively introduces a solution discharged from either the first reactor 140 or the second reactor 160 into the evaporator 200 . If the liquid lithium carbonate (Li ₂ CO ₃ ) generated in the first reactor 140 is introduced into the evaporator 200 without flowing into the second reactor 160 , finally lithium carbonate through the evaporation and concentration process (Li ₂ CO ₃ ) The crystal is recovered.

In order to recover the solid transition metal oxide generated through the water washing process in the first reactor 140 , the transition metal recovery chamber 141 dries the solid transition metal oxide introduced from the first reactor 140 , The transition metal oxide powder is recovered.

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_{In addition, in order to recover the solid calcium carbonate (CaCO 3} ) generated in the second reactor 140 , the calcium carbonate recovery chamber 161 is a solid calcium carbonate (CaCO ₃ ) generated in the second reactor 140 . is dried to recover calcium carbonate powder.

The evaporator 200 heats the liquid lithium carbonate (Li ₂ CO ₃ ) introduced from the first reactor 140 or liquid lithium hydroxide (LiOH) introduced from the second reactor 160 with high-temperature steam to evaporate and concentrate. A concentrated solution is produced.

The evaporator 200 may be configured to include a first heat exchanger 210 and a second heat exchanger 220 for a more efficient evaporation and concentration process. The first heat exchanger 210 converts the liquid lithium carbonate (Li ₂ CO ₃ ) introduced from the first reactor 140 or the liquid lithium hydroxide (LiOH) introduced from the second reactor into the high-temperature steam generator 180 . ) to form a primary concentrate through heat exchange using the high-temperature steam received through Thereafter, the second heat exchanger 220 further evaporates the primary concentrate introduced from the primary evaporator to form a secondary concentrate. The second heat exchanger 220 may be of a vertical tube falling film (VTFF) type, in which the falling film type includes a plurality of evaporation tubes therein, and the concentrated liquid flowing into the heat exchanger passes through the inner wall of the evaporation tube. It is characterized in that it is evaporated by heat exchange with high-temperature steam supplied to the outer wall side of the evaporation tube as it flows through the descending dura mater. This descending film method can suppress the rise of the boiling point without loss of internal pressure, and the heat transfer rate is very high even if the temperature difference with the heating fluid is small, so that the contact time with the heating body such as water vapor can be minimized, and it is maintained at about 1 ~ 2 mm There is an advantage in that the temperature gradient in the liquid dura mater is very small, so that the temperature rise of the heat-sensitive liquid can be minimized.

The second heat exchanger 220 may perform an evaporation concentration process through reduced pressure evaporation inside, and preferably, the evaporation concentration may be performed in a vacuum with an internal pressure of about 10-2 mmHg or less. have.

The steam used after being input to the second heat exchanger 220 may be re-introduced into the second heat exchanger 220 using a mechanical low pressure vapor recompressor (MVR).

The evaporator 200 may further include a forced circulation evaporator 230 for crystallization of the concentrate that has passed through the first and second heat exchangers 210 and 220 . The forced circulation evaporator 230 is a third heat exchanger 231 that heats the concentrated liquid introduced from the second heat exchanger 220 through a heat medium, and the concentrated liquid that has passed through the third heat exchanger is sprayed into the chamber and evaporated. It can be divided by including a gas-liquid separation device 232 that separates the vapor from the concentrate. The concentrated liquid discharged from the gas-liquid separator 232 may be recirculated back to the third heat exchanger 231 according to a predetermined condition through a pump.

The vapor separated in the forced circulation evaporator 200 may be transferred to the distilled water storage unit 150 through the recirculation transfer line 190 and recirculated to be used in the water washing process. At this time, the separated vapor may be first introduced into the compressor 180 and compressed, and then transferred to the distilled water storage unit 150 through the recirculation transfer line 190 .

The degree of concentration performed in the evaporative concentration process through the evaporator 200 is preferably a degree that lithium compound crystals are not generated, otherwise the crystal powder may remain in the heat exchanger, etc., and thus the efficiency may be reduced.

Finally, it is preferable to further include a moisture remover 240 for recovering the solid lithium compound crystals from the tertiary concentrate introduced from the forced circulation evaporator 230 . The water remover 240 may be any device capable of removing water, and may be, for example, a centrifugal separator using centrifugal force.

Next, a lithium recovery method according to an embodiment of the present invention will be described.

3 is a flowchart schematically illustrating a lithium recovery method according to an embodiment of the present invention.

First, a lithium transition metal oxide is calcined at a temperature of 600° C. to 800° C. in an oxygen-free reducing atmosphere _{to produce a product including a lithium carbonate (Li 2} CO ₃ ) compound and a transition metal oxide. (Step S100 ) This step is performed in the firing chamber 120 , and it is preferable that carbon dioxide (CO _{2 ) gas is injected from the CO 2 supplier 130 to be fired.}

Next, the product is washed with distilled water to generate liquid lithium carbonate (Li ₂ CO ₃ ) and phase-separated from the solid transition metal oxide (step S200). This is a product after calcination, lithium carbonate (Li ₂ CO ₃ ) and Since the transition metal oxide has a difference in solubility in water, the lithium carbonate (Li ₂ CO ₃ ) is converted into a liquid lithium carbonate (Li ₂ CO ₃ ) and the transition metal oxide is a solid phase through a water washing process. have. The volume ratio of the product and water may be 1:1 to 1:30. In addition, the water washing process may be repeated 1 to 3 times, and the process time of one water washing process may be 30 minutes to 2 hours.

The liquid lithium carbonate (Li ₂ CO ₃ ) is reacted with calcium hydroxide (Ca(OH) ₂ ) to produce liquid lithium hydroxide (LiOH) and solid calcium carbonate (CaCO ₃ ). (Step S300)

Finally, the liquid lithium hydroxide (LiOH) produced above is evaporated and concentrated by heat exchange with high-temperature steam to obtain a solid lithium-containing compound. (Step S400) Heat exchange in this step is performed at least twice or more. Preferably, the evaporation concentration process is performed through a heat exchanger. At this time, for process efficiency, the heat exchanger is operated at a low temperature and in a vacuum to lower the evaporation temperature, and a vapor recompression method may be applied to minimize the amount of steam used. In addition, the steam after heat exchange is compressed, stored, transferred to the product washing process of the calcination process, and reused, thereby enabling a continuous process.

The concentrated liquid evaporated through the heat exchange is preferably dehydrated through a dehydrating device such as a centrifugal separator to obtain a solid lithium-containing compound.

For reference, the solid transition metal oxide generated in the first reactor may be transferred to a separate transition metal recovery chamber 141 and dried to recover the transition metal oxide form. In this case, a separate wet process (solvent extraction after acid leaching) may be applied to recover the oxide form in the form of transition metal powder.

In addition, the solid calcium carbonate (CaCO ₃ ) generated in the second reactor may be transferred to a separate calcium carbonate recovery chamber 151 and dried to be recovered as calcium carbonate powder.

Although the above has been described with reference to the preferred embodiments of the present invention, those skilled in the art can variously modify and change the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. You will understand that you can.

100: lithium recovery system
110: lithium transition metal storage unit 120: firing chamber
130: CO2 supplier 140: first reactor
141: transition metal recovery chamber 150: distilled water storage unit
151: calcium carbonate recovery chamber 160: second reactor
170: optional connection 180: compressor
200: evaporator 210: first heat exchanger
220: second heat exchanger 230: forced circulation evaporator
231: third heat exchanger 232: gas-liquid separation device
240: moisture eliminator

Claims (14)

a lithium transition metal storage unit accommodating a lithium transition metal oxide;
The lithium transition metal oxide introduced from the lithium transition metal storage unit is calcined at a temperature of 600° C. to 800° C. in a reducing atmosphere under anoxic conditions _{to produce a product containing a lithium carbonate (Li 2} CO ₃ ) compound and a transition metal oxide. firing chamber;
a first reactor for washing the product introduced from the calcination chamber with distilled water flowing from the distilled water storage unit _{to generate liquid lithium carbonate (Li 2} CO ₃ ) and phase-separating the solid transition metal oxide;
Liquid lithium carbonate (Li ₂ CO ₃ ) introduced from the first reactor reacts with calcium hydroxide (Ca(OH) ₂ ) to produce liquid lithium hydroxide (LiOH) and solid calcium carbonate (CaCO ₃ ) reactor; and
an evaporator for generating a concentrated solution obtained by evaporating and concentrating liquid lithium carbonate (Li ₂ CO ₃ ) introduced from the first reactor or liquid lithium hydroxide (LiOH) introduced from the second reactor by heat exchange with high-temperature steam;
Lithium recovery system comprising a.
According to claim 1,
The lithium recovery system further comprising a; located in front of the evaporator, the selective connection for selectively introducing the solution discharged from either the first reactor or the second reactor into the evaporator.
According to claim 1,
The evaporator is a primary heat exchanger for first evaporating liquid lithium carbonate (Li ₂ CO ₃ ) introduced from the first reactor or liquid lithium hydroxide (LiOH) introduced from the second reactor to form a primary concentrate ; A lithium recovery system comprising a; a secondary heat exchanger for further evaporating the primary concentrate introduced from the primary heat exchanger to form a secondary concentrate.
4. The method of claim 3,
The evaporator further includes a forced circulation type evaporator for further evaporating the secondary concentrate to form a tertiary concentrate, and to store the heat-exchanged vapor.
5. The method of claim 4,
A lithium recovery system further comprising a; a recirculation transfer line for recirculating the vapor stored in the forced circulation evaporator by transferring it to the distilled water storage unit.
5. The method of claim 4,
The lithium recovery system further comprising a; water remover for dehydrating the tertiary concentrate introduced from the forced circulation evaporator to produce a solid lithium compound crystal. According to claim 1,
A lithium recovery system for firing a lithium transition metal oxide by injecting carbon dioxide (CO _{2 ) gas into the firing chamber.}
According to claim 1,
The lithium recovery system further comprising; a transition metal recovery chamber for recovering the transition metal powder by drying the solid transition metal oxide introduced from the first reactor.
According to claim 1,
The lithium recovery system further comprising a; calcium carbonate recovery chamber for recovering the calcium carbonate powder by drying the solid calcium carbonate (CaCO _{3 ) introduced from the second reactor.}
1 step of calcining the lithium transition metal oxide at a temperature of 600° C. to 800° C. in a reducing atmosphere under anoxic conditions _{to produce a product including a lithium carbonate (Li 2} CO ₃ ) compound and a transition metal oxide;
a second step of washing the product with distilled water to generate liquid lithium carbonate (Li ₂ CO ₃ ) and phase-separating the solid transition metal oxide;
Step 3 of reacting the generated liquid lithium carbonate (Li ₂ CO ₃ ) with calcium hydroxide (Ca(OH) ₂ ) to produce liquid lithium hydroxide (LiOH) and solid calcium carbonate (CaCO _{3 );} and
a fourth step of evaporating and concentrating the generated liquid lithium hydroxide (LiOH) by heat exchange with high-temperature steam to obtain solid lithium hydroxide;
comprising, a lithium recovery method.
11. The method of claim 10,
Lithium recovery method, characterized in that the steam after heat exchange is transferred for use in the water washing in the second step.
11. The method of claim 10,
The method for recovering lithium, characterized in that the heat exchange is performed at least twice or more.
11. The method of claim 10,
In order to obtain solid lithium hydroxide (LiOH), the lithium recovery method, characterized in that dehydration through a water remover after evaporation and concentration by heat exchange.
11. The method of claim 10,
In the sintering process, carbon dioxide (CO ₂ ) gas is injected to sinter the lithium transition metal oxide, the lithium recovery method.

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