METHOD FOR RECOVERING WASTE LITHIUM COBALT OXIDE BATTERY

Abstract

Disclosed is a method for recovering a waste lithium cobalt oxide battery, the method comprising: feeding a lithium cobalt oxide battery black powder in a column-shaped container, adding a first acid to the column-shaped container for heat leaching until solids in the column-shaped container are not reduced any more so as to obtain a first leachate and leaching residues, wherein the first acid is a weak acid, and a filtering structure is arranged at the bottom of the column-shaped container; and adding a second acid to the column-shaped container containing the leaching residues for heat leaching until solids in the column-shaped container are not reduced any more so as to obtain a second leachate and graphite, wherein the second acid is a strong acid. According to the present invention, consumption of an inorganic strong acid can be reduced, emission of strong acid gas is reduced, and green and low-carbon heat leaching of the black powder is achieved.

Claims

1. A method for recycling a spent lithium cobalt oxide battery, comprising the following steps: S1: putting black powders from a lithium cobalt oxide battery into a column-shaped container, adding a first acid to the column-shaped container for hot leaching until solids in the column-shaped container no longer decrease, to obtain a first leachate and a leaching residue, wherein the first acid is selected from the group consisting of methanoic acid, acetic acid, benzoic acid and a mixture thereof, and the concentration of the first acid is 0.1-35 wt %; the bottom of the column-shaped container is provided with a filter structure; the first acid has a temperature of 35-80? C., and the first acid further contains sodium thiosulfate in an amount of 0.1-12 wt %; and S2: adding a second acid to the column-shaped container containing the leaching residue for hot leaching until solids in the column-shaped container no longer decrease, to obtain a second leachate and graphite, wherein the second acid is a strong acid.

2. The method according to claim 1, wherein in S1, the black powders from a lithium cobalt oxide battery is obtained by: disassembling the spent lithium cobalt oxide battery to obtain cells, measuring the voltage of the cells to classify the cells into low-voltage cells and high-voltage cells, discharging, pyrolyzing and crushing the low-voltage cells, and removing copper-aluminum foils and separators to obtain the black powders from a lithium cobalt oxide battery.

3. The method according to claim 2, wherein the high-voltage cells are assembled into a battery pack to provide power for heating.

4. The method according to claim 1, further comprising a step of producing cobalt oxalate from the first leachate by adding alkali to the first leachate to adjust pH and separating aluminium hydroxide precipitations; adding the second acid to adjust pH to 3.0-4.5, adding a synergistic extractant for extraction and separating a cobalt-containing phase; adding the second acid to the cobalt-containing phase for back-extraction and separating an aqueous phase by back-extraction; and adding a compound containing oxalate to the aqueous phase from the back-extraction and obtaining a cobalt oxalate by solid-liquid separation.

5. The method according to claim 1, wherein in S2, to the second leachate, adding aluminum powders to separate out copper sponge, and adding alkali to adjust pH to 4.0-6.5, and separating out aluminium hydroxide.

6. (canceled)

7. (canceled)

8. The method according to claim 1, wherein in S2, the second acid is selected from the group consisting of hydrochloric acid, phosphoric acid, sulfuric acid, nitric acid and a mixture thereof; the concentration of the second acid is 0.01-0.2 mol/L; and the second acid has a temperature of 35-80? C.

9. The method according to claim 4, wherein the synergistic extractant consists of extractant and cyclohexane at a mass ratio of (15-50):(30-85), wherein the extractant consists of dialkyl hypophosphorous acid and mono-2-ethylhexyl (2-ethylhexyl)phosphonate at a volume ratio of (1-4):(1-10).

10. The method according to claim 4, wherein the compound containing oxalate is selected from the group consisting of oxalic acid, ammonium oxalate, sodium oxalate and a mixture thereof.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0028] The present disclosure will be further described in conjunction with the accompanying drawings and examples.

[0029] FIG. 1 is a schematic drawing illustrating hot leaching in Example 1 of the present disclosure.

DETAILED DESCRIPTION

[0030] The concept of the present invention and the technical effects produced will be clearly and completely described below with reference to the examples, so as to aid in fully understanding the purpose, characteristics and effects of the present invention. Obviously, the described examples are only a part of the examples of the present invention, rather than all of them. All the other examples, which is based on these examples of this invention, obtained by a person having ordinary skill in the art without creative labor should fall within the protection scope of the present invention.

EXAMPLES

Example 1

[0031] Referring to FIG. 1, provided is a method for recycling spent lithium cobalt oxide battery with a specific process as follows.

[0032] Classification: Spent power battery packs (or modules) were split into cells. These cells were classified into the first spent power cells (<2.5V) and into the second spent power cells (?2.5V), according to their measured residual output voltage. The first spent power cells were immersed in a bucket containing a tap water discharge solution for 5 days to discharge them, then pyrolyzed in a kiln at 840? C. for about 7.5 h, cooled down, crushed, and screened to remove copper-aluminum foils and separators, then black powder was obtained. 5 second spent power cells were connected in series to obtain a single string of 16V cell stack, and then 3 strings of the cell stacks were connected in parallel, connected with circuit protection boards, and cover with refractory film, to obtain a 5S3P 16V battery pack as a heating power. The measured main components of the black powder are shown in Table 1.

TABLE-US-00001 TABLE 1 Components Cobalt Lithium Aluminum Copper Graphite Content (%) 36.4 4.3 3.1 7.8 13.6 [0033] 2. Selective Hot Leaching: 400 g of the black powder was put into a long cylinder with an acid-resistant polytetrafluoroethylene interior (and with a filter screen at the bottom). The 16V battery pack was connected to a heater to heat acetic acid to about 58? C. 15.4 wt % acetic acid (containing 4.7 wt % of sodium thiosulfate) was poured into the long cylinder, to perform hot leaching under stirring. The hot leaching was continued until solids in the container no longer decrease. A total of 6.8 L of acetic acid was consumed. By filtration through the filter screen, 6.6 L of a first leachate flowing through the container (the measured components of the first leachate were: cobalt 19.3 g/L, lithium 2.4 g/L, aluminum 0.16 g/L, and copper 0.20 g/L, from which the calculated leaching rate of cobalt was 87.5%, leaching rate of aluminum was 8.5%, and leaching rate of copper was 4.2%), and a leaching residue inside the container were obtained. The 16V battery pack was connected to the heater to heat sulfuric acid to about 68? C. To the leaching residue, 7.7 wt % of sulfuric acid was added to continue hot leaching until the leaching residue in the container no longer decrease. A total of 0.8 L of sulfuric acid was consumed. By the filtration with the filter screen, graphite and a second leachate were obtained. By adding 9 g of aluminum powder to the second leachate, 29.6 g of copper sponge was obtained through separation. 0.15 mol/L of sodium hydroxide (containing 10.6 wt % of sodium carbonate) was added to adjust the second leachate to pH-6.1. After press-filtration, 59.3 g of aluminium hydroxide was obtained.

[0034] 3. Extraction and Preparation of Cobalt Oxalate: To the first leachate, 0.15 mol/L of sodium hydroxide (containing 10.1 wt % of sodium carbonate) was added to control pH=6.3, and then 3.9 g of aluminium hydroxide precipitate was obtained through separation. Next, 14.1 wt % of sulfuric acid was added to control pH=3.7, and mixed with a novel synergistic extractant (prepared by mixing 1.5:3.5:10 of dialkyl hypophosphorous acid: mono-2-ethylhexyl (2-ethylhexyl)phosphonate: cyclohexane, and adding 0.15 mol/L of sodium hydroxide, 40% saponification) for extraction. The mixture was shaken at 60? C. for 30 min in a shaking box, and stood for 12 min. After separation, the obtained cobalt-containing phase was added with 7.1 wt % of sulfuric acid to perform back-extraction. After separation, an aqueous phase by back-extraction was obtained. To the aqueous phase from the back-extraction, sodium oxalate was added until no more precipitation. After solid-liquid separation, a solid was obtained, washed, and dried, which yielded 323 g of battery-grade light red cobalt oxalate.

Example 2

[0035] A method for recycling spent lithium cobalt oxide battery had a specific process as follows. [0036] 1. Classification: Spent power battery packs (or modules) were split into cells. These cells were classified into the first spent power cells (<2.5V) and the second spent power cells (?2.5V), according to their measured residual output voltage. The first spent power cells were immersed in a bucket containing tap water discharge solution for 5 days to discharge them, then pyrolyzed in a kiln at 840? C. for about 7.5 h, cooled down, crushed, and screened to remove copper-aluminum foils and separators. Black powder was obtained. 5 second spent power cells were connected in series to obtain a single string of 16V cell stack. 3 strings of the cell stacks were connected in parallel, connected with circuit protection boards, and covered with refractory film, to obtain a 5S3P 16V battery pack as a heating power. The measured main components of the black powder are shown in Table 2.

TABLE-US-00002 TABLE 2 Components Cobalt Lithium Aluminum Copper Graphite Content (%) 36.4 4.3 3.1 7.8 13.6 [0037] 2. Selective Hot Leaching: 400 g of the black powder was put into a long cylinder with an acid-resistant polytetrafluoroethylene interior (and with a filter screen at the bottom). The 16V battery pack was connected to a heater to heat acetic acid to about 68? C. 15.4 wt % of acetic acid (containing 4.7 wt % of sodium thiosulfate) was poured into the long cylinder, to perform hot leaching under stirring. The hot leaching was continued until solids in the container no longer decrease. A total of 5.3 L of acetic acid was consumed. By filtration through the filter screen, 5.1 L of a first leachate flowing through the container (the measured components of the first leachate were: cobalt 26.3 g/L, lithium 3.2 g/L, aluminum 0.24 g/L, copper 0.53 g/L, from which the calculated leaching rate of cobalt was 92.1%, leaching rate of aluminum was 9.8%, and leaching rate of copper was 8.6%), and a leaching residue inside the container were obtained. The 16V battery pack was connected to the heater to heat sulfuric acid to about 73? C. To the leaching residue, 7.7 wt % of sulfuric acid was added to continue hot leaching until the leaching residue in the container no longer decrease. A total of 0.7 L of sulfuric acid was consumed. By the filtration with the filter screen, graphite and a second leachate were obtained. By adding 9 g of aluminum powder to the second leachate, and after separation, copper sponge was obtained. 0.15 mol/L of sodium hydroxide (containing 10.1 wt % of sodium carbonate) was added to adjust the second leachate to pH=6.1. After press-filtration, 59.6 g of aluminium hydroxide was obtained. [0038] 3. Extraction and Preparation of Cobalt Oxalate: To the first leachate, 0.10 mol/L of sodium hydroxide (containing 5.1 wt % of sodium carbonate) was added to control pH=6.5, and then 4.1 g of aluminium hydroxide precipitate was obtained through separation. Next, 14.1 wt % of sulfuric acid was added to control pH=3.8, and mixed with a novel synergistic extractant (prepared by mixing 1.5:3:10 of dialkyl hypophosphorous acid: mono-2-ethylhexyl (2-ethylhexyl)phosphonate: cyclohexane, and adding 0.15 mol/L of sodium hydroxide, 40% saponification) to perform extraction. The mixture was blended, shaken at 60? C. for 30 min in a shaking box, and stood for 12 min. After separation, the obtained cobalt-containing phase was added with 7.1 wt % of sulfuric acid to perform back-extraction. After separation, an aqueous phase by back-extraction was obtained. To the aqueous phase from the back-extraction, sodium oxalate was added until no more precipitation. After solid-liquid separation, a solid was obtained, washed, and dried, which yielded 326 g of battery-grade light red cobalt oxalate.

Example 3

[0039] A method for recycling spent lithium cobalt oxide battery had a specific process as follows. [0040] 1. Classification: Spent power battery packs (or modules) were split into cells. These cells were classified into the first spent power cells (<2.5V) and into the second spent power cells (?2.5V), according to their measured residual output voltage. The first spent power cells were immersed in a bucket containing tap water discharge solution for 5 days to discharge them, then pyrolyzed in a kiln at 650? C. for about 12 h, cooled down, crushed, and screened to remove copper-aluminum foils and separators. Black powder was obtained. 5 second spent power cells were connected in series to obtain a single string of 16V cell stack. 3 strings of the cell stacks were connected in parallel, connected with circuit protection boards, and covered with refractory film, to obtain a 5S3P 16V battery pack as a heating power. The measured main components of the black powder are shown in Table 3.

TABLE-US-00003 TABLE 3 Components Cobalt Lithium Aluminum Copper Graphite Content (%) 36.6 4.4 3.2 7.7 13.3 [0041] 2. Selective Hot Leaching: 400 g of the black powder was put into a long cylinder with an acid-resistant polytetrafluoroethylene interior (and with a filter screen at the bottom). The 16V battery pack was connected to a heater to heat acetic acid to about 74? C. 15.4 wt % of acetic acid (containing 4.7 wt % of sodium thiosulfate) was poured into the long cylinder, to perform hot leaching under stirring. The hot leaching was continued until solids in the container no longer decrease. A total of 4.8 L of acetic acid was consumed. By filtration through the filter screen, 4.6 L of a first leachate flowing through the container (the measured components of the first leachate were: cobalt 29.5 g/L, lithium 3.6 g/L, aluminum 0.29 g/L, copper 0.43 g/L, from which the calculated leaching rate of cobalt was 92.7%, leaching rate of aluminum was 10.4%, and leaching rate of copper was 6.5%), and a leaching residue inside the container were obtained. The 16V battery pack was connected to the heater to heat sulfuric acid to about 78? C. To the leaching residue, 7.7 wt % of sulfuric acid was added to continue hot leaching until the leaching residue in the container no longer decrease. A total of 0.6 L of sulfuric acid was consumed. By the filtration with the filter screen, graphite and a second leachate were obtained. By adding 10 g of aluminum powder to the second leachate, and after separation, copper sponge was obtained. 0.15 mol/L of sodium hydroxide (containing 10.1 wt % of sodium carbonate) was added to adjust the second leachate to pH-6.3. After press-filtration, 61.1 g of aluminium hydroxide was obtained. [0042] 3. Extraction and Preparation of Cobalt Oxalate: To the first leachate, 0.15 mol/L of sodium hydroxide (containing 10.1 wt % of sodium carbonate) was added to control pH=6.3, and then 4.3 g of aluminium hydroxide precipitate was obtained through separation. Next, 14.1 wt % of sulfuric acid was added to control pH=3.9, and mixed with a novel synergistic extractant (prepared by mixing 1.5:3:8 of dialkyl hypophosphorous acid: mono-2-ethylhexyl (2-ethylhexyl)phosphonate: cyclohexane, and adding 0.15 mol/L of sodium hydroxide, 45% saponification) to perform extraction. The mixture was blended, shaken at 60? C. for 30 min in a shaking box, and stood for 12 min. After separation, the obtained cobalt-containing phase was added with 7.1 wt % of sulfuric acid to perform back-extraction. After separation, an aqueous phase by back-extraction was obtained. To the aqueous phase from the back-extraction, sodium oxalate was added until no more precipitation. After solid-liquid separation, a solid was obtained, washed, and dried, which yielded 332 g of battery-grade light red cobalt oxalate.

Example 4

[0043] A method for recycling spent lithium cobalt oxide battery had a specific process as follows. [0044] 1. Classification: Spent power battery packs (or modules) were split into cells. These cells were classified into the first spent power cells (<2.5V) and into the second spent power cells (?2.5V), according to their measured residual output voltage. The first spent power cells were immersed in a bucket containing tap water discharge solution for 5 days to discharge them, then pyrolyzed in a kiln at 650? C. for about 12 h, cooled down, crushed, and screened to remove copper-aluminum foils and separators. Black powder was obtained. 6 second spent power cells were connected in series to obtain a single string of 19V cell stack. 4 strings of the cell stacks were connected in parallel, connected with circuit protection boards, cover with refractory film, to obtain a 6S4P 19V battery pack as heating power. The measured main components of the black powder are shown in Table 4.

TABLE-US-00004 TABLE 4 Components Cobalt Lithium Aluminum Copper Graphite Content (%) 36.6 4.4 3.2 7.7 13.3 [0045] 2. Selective Hot Leaching: 400 g of the black powder was put into a long cylinder with an acid-resistant polytetrafluoroethylene interior (and with a filter screen at the bottom). The 19V battery pack was connected to a heater to heat acetic acid to about 87? C. 26.6 wt % of formic acid (containing 7.3 wt % of sodium thiosulfate) was poured into the long cylinder, to perform hot leaching under stirring. The hot leaching was continued until solids in the container no longer decrease. A total of 3.6 L formic acid was consumed. By filtration through the filter screen, 3.4 L of a first leachate flowing through the container (the measured components of the first leachate were: cobalt 40.7 g/L, lithium 4.99 g/L, aluminum 0.47 g/L, copper 0.72 g/L, from which the calculated leaching rate of cobalt was 94.5%, leaching rate of aluminum was 12.5%, and leaching rate of copper was 7.3%), and a leaching residue inside the container were obtained. The 19V battery pack was connected to the heater to heat sulfuric acid to about 85? C. To the leaching residue, 7.9 wt % of sulfuric acid was added to continue hot leaching until the leaching residue in the container no longer decrease. A total of 0.5 L of sulfuric acid was consumed in total sulfuric acid. By the filtration with the filter screen, graphite and a second leachate were obtained. By adding 11 g of aluminum powder to the second leachate, and after separation, copper sponge was obtained. 0.15 mol/L of sodium hydroxide (containing 10.1 wt % of sodium carbonate) was added to adjust the second leachate to pH-6.2. After press-filtration, 63.8 g of aluminium hydroxide was obtained. [0046] 3. Extraction and Preparation of Cobalt Oxalate: To the first leachate, 0.15 mol/L of sodium hydroxide (containing 10.1 wt % of sodium carbonate) was added to control pH=6.3, and then 4.6 g of aluminium hydroxide precipitate was obtained through separation. Then, 14.1 wt % of sulfuric acid was added to control pH-3.6, and mixed with a novel synergistic extractant (prepared by mixing 1.5:2.5:8 of dialkyl hypophosphorous acid: mono-2-ethylhexyl (2-ethylhexyl)phosphonate: cyclohexane, and adding 0.15 mol/L of sodium hydroxide, 50% saponification) to perform extraction. The mixture was blended, shaken at 60? C. for 30 min in a shaking box, and stood for 12 min. After separation, the obtained cobalt-containing phase was added with 7.1 wt % of sulfuric acid to perform back-extraction. After separation, an aqueous phase by back-extraction was obtained. To the aqueous phase from the back-extraction, sodium oxalate was added until no more precipitation. After solid-liquid separation, a solid was obtained, washed, and dried, which yielded 339 g of battery-grade light red cobalt oxalate.

Example 5

[0047] A method for recycling spent lithium cobalt oxide battery had a specific process as follows. [0048] 1. Classification: Spent power battery packs (or modules) were split into cells. These cells were classified into the first spent power cells (<2.5V) and into the second spent power cells (?2.5V), according to their measured residual output voltage. The first spent power cells were immersed in a bucket containing tap water discharge solution for 5 days to discharge them, then pyrolyzed in a kiln at 650? C. for about 12 h, cooled down, crushed, and screened to remove copper-aluminum foils and separators. Black powder was obtained. 6 second spent power cells were connected in series to obtain a single string of 19V cell stack. 4 strings of the cell stacks were connected in parallel, connected with circuit protection boards, cover with refractory film, to obtain a 6S4P 19V battery pack as heating power. The measured main components of the black powder are shown in Table 5.

TABLE-US-00005 TABLE 5 Components Cobalt Lithium Aluminum Copper Graphite Content (%) 36.6 4.4 3.2 7.7 13.3 [0049] 2. Selective Hot Leaching: 400 g of the black powder was put into a long cylinder with an acid-resistant polytetrafluoroethylene interior (and with a filter screen at the bottom). The 19V battery pack was connected to a heater to heat acetic acid to about 95? C. 26.6 wt % of formic acid (containing 7.3 wt % of sodium thiosulfate) was poured into the long cylinder, to perform hot leaching under stirring. The hot leaching was continued until solids in the container no longer decrease. A total of 3.2 L formic acid was consumed. By filtration through the filter screen, 3.1 L of a first leachate flowing through the container (the measured components of the first leachate were: cobalt 45.9 g/L, lithium 6.0 g/L, aluminum 0.65 g/L, copper 0.95 g/L, from which the calculated leaching rate of cobalt was 97.2%, leaching rate of aluminum was 15.7%, and leaching rate of copper was 10.5%), and a leaching residue inside the container were obtained. The 19V battery pack was connected to the heater to heat sulfuric acid to about 95? C. To the leaching residue, 7.7 wt % of sulfuric acid was added to continue hot leaching until the leaching residue in the container no longer decrease. A total of 0.4 L of sulfuric acid was consumed. By the filtration with the filter screen, graphite and a second leachate were obtained. By adding 12 g of aluminum powder to the second leachate, and after separation, copper sponge was obtained. 0.15 mol/L of sodium hydroxide (containing 10.1 wt % of sodium carbonate) was added to adjust the second leachate to pH=6.1. After press-filtration, 65.3 g of aluminium hydroxide was obtained. [0050] 3. Extraction and Preparation of Cobalt Oxalate: To the first leachate, 0.15 mol/L of sodium hydroxide (containing 10.1 wt % of sodium carbonate) was added to control pH-6.3, and then 4.7 g of aluminium hydroxide precipitate was obtained through separation. Then, 14.1 wt % of sulfuric acid was added to control pH=3.5, and mixed with a novel synergistic extractant (prepared by mixing 1.5:3.5:9 of dialkyl hypophosphorous acid: mono-2-ethylhexyl (2-ethylhexyl)phosphonate: cyclohexane, and adding 0.15 mol/L of sodium hydroxide, 50% saponification) to perform extraction. The mixture was blended, shaken at 60? C. for 30 min in a shaking box, and stood for 12 min. After separation, a cobalt-containing phase was obtained. 7.1 wt % of sulfuric acid was added to perform back-extraction. After separation, an aqueous phase by back-extraction was obtained. To the aqueous phase from the back-extraction, sodium oxalate was added until no more precipitation. After solid-liquid separation, a solid was obtained, washed, and dried, which yielded 348 g of battery-grade light red cobalt oxalate.

TABLE-US-00006 TABLE 6 Contents of cobalt and other impurities in cobalt oxalate of Examples 1-5 Cobalt Copper Aluminum Sodium Iron Examples (%) (%) (%) (%) (%) Example 1 31.54 0.00031 0.000071 0.00023 0.00034 Example 2 31.59 0.00024 0.000077 0.00018 0.00031 Example 3 31.54 0.00037 0.00074 0.00021 0.00037 Example 4 31.63 0.00030 0.00060 0.00017 0.00052 Example 5 31.66 0.00034 0.00064 0.00016 0.00053

[0051] It can be seen from Table 6 that cobalt oxalate prepared in Examples 1-5 had a cobalt content >31.5%, a copper content <0.0008%, an aluminum content <0.001%, a sodium content <0.001%, and an iron content <0.001%, and the purities fully meet the requirements of GB/T 26005-2010 for battery-grade cobalt oxalate. This demonstrated that the synergistic extractant of the present disclosure has high selectivity and excellent extraction effect on cobalt.

[0052] Above, the present invention has been described in detail in conjunction with examples, but it is not limited to the above-mentioned examples. Various changes thereof can be made by those of ordinary skill in the art within the scope of their knowledge and without departing from the spirit of the present invention. In addition, the examples of the present invention and features in the examples may be combined with each other without conflict.