Method for homologous modification complementary leaching of cobalt-containing waste lithium battery

Abstract

The application discloses a method for homologous modification complementary leaching of cobalt-containing waste lithium batteries, which comprises the steps of discharging, preparing positive black powder and alloy powder, complementary leaching, removing copper, iron and aluminum, preparing ternary hydroxide, evaporating ammonia and depositing lithium, etc. The cobalt-containing waste lithium batteries are prepared into positive black powder and alloy powder respectively. The positive black powder is directly added with acid for complementary leaching by using the oxidizability of the positive black powder and the reducibility of the alloy powder, without adding additional reducing agent and oxidizing agent, so that the harm of SO2 gas generated by adding sulfite during acid leaching of the positive black powder is avoided, and the safety hidden danger of a large amount of hydrogen gas generated during direct acid leaching of the alloy powder obtained by the traditional pyrometallurgical process is also avoided. The leaching speed of the process is fast, and the leaching rates of valuable elements cobalt, nickel, manganese, copper and lithium are all higher than 99.5%. The production safety of the process is good, the process is economic and environmentally friendly, and is easy to be applied to industrialization.

Description

Technical Field

[0001] This invention relates to a method for recycling waste lithium batteries in the metallurgical field, and more specifically to a method for homogeneous modification and complementary leaching of cobalt-containing waste lithium batteries (lithium cobalt oxide batteries, ternary lithium batteries). Background Technology

[0002] There are numerous methods for treating and recycling waste lithium batteries, typically including pyrometallurgical, hydrometallurgical, and bioleaching methods. Pyrometallurgical processes are relatively simple, but energy consumption is high, generating a large amount of waste gas. Hydrometallurgical processes mainly use inorganic or organic acids to leach the metals. Using inorganic acids (HCl, H2SO4, HNO3, etc.) as leaching agents results in high leaching rates and large processing volumes, but produces toxic and harmful gases (Cl2, SO2, NO2), and the residual acidic waste liquid is difficult to treat, leading to secondary pollution. Using organic acids (citric acid, oxalic acid, ascorbic acid, gluconic acid, etc.) as leaching agents is effective for treating ternary lithium-ion power batteries, producing acidic waste liquid with low acidity, facilitating subsequent treatment and recycling; however, organic acid raw materials are more expensive than inorganic acids, and the subsequent nickel-cobalt-manganese separation process is more complex, further increasing recycling costs. Bioleaching is low-cost and environmentally friendly, but bacteria are difficult to cultivate, the leaching cycle is long, and the leaching rate is low, which limits its industrial application. Therefore, existing technologies still need improvement and development. Optimized combinations of various leaching methods may be the most ideal treatment approach, and many researchers are continuously studying and optimizing them. Summary of the Invention

[0003] In view of the defects and shortcomings of the existing technology, the purpose of this invention is to provide a method for homogeneous modification and complementary leaching of cobalt-containing waste lithium batteries.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for homogeneous modification and complementary leaching of cobalt-containing waste lithium batteries, the method comprising the following steps:

[0006] S1 Discharge: Put the cobalt-containing waste lithium battery into a discharge battery containing a sodium salt solution of NaCl and / or Na2SO4, discharge for 24h to 48h, drain, and the drained water is reused in the discharge battery.

[0007] S2 Preparation of cathode black powder and alloy powder: The discharged cobalt-containing waste lithium batteries are divided into two parts according to their size. The large-sized cobalt-containing waste lithium batteries are used to prepare cathode black powder, and the small-sized cobalt-containing waste lithium batteries are used to prepare alloy powder.

[0008] S3 complementary leaching: The obtained positive electrode black powder and alloy powder are mixed according to the principle of electron gain and loss balance, and the weight ratio of the two is 1:1 to 3:1. The mixture is then leached in dilute acid.

[0009] S4 Copper, Iron and Aluminum Removal: After leaching, add ammonium bicarbonate or ammonia to adjust the pH to 2.5-3, add ammonium sulfide to precipitate Cu and separate solid and liquid, and recover copper sulfide slag; add ammonium bicarbonate or ammonia to the filtrate to raise the pH to 5-6, precipitate Fe and Al and separate solid and liquid, to obtain impurity-removed filtrate and iron and aluminum slag;

[0010] S5 Preparation of ternary hydroxide: The filtrate containing Mn, Co, Ni and Li obtained in step S4 is supplemented with an appropriate amount of one or two of Mn salt, Co salt and Ni salt as needed; NaOH solution and ammonia water are added in an inert atmosphere at 45℃~55℃ for co-precipitation, and nickel-cobalt-manganese ternary hydroxide and co-precipitated liquid are obtained after solid-liquid separation;

[0011] S6 Ammonia stripping: The co-precipitated liquid obtained in step S5 is heated with steam to strip ammonia, resulting in a stripped liquid and ammonia gas.

[0012] S7 Lithium precipitation: Add a carbonate solution to the liquid obtained after ammonia stripping in step S6 to precipitate lithium, and obtain lithium carbonate.

[0013] It should be noted that step S2 further includes:

[0014] S2.1 Preparation of cathode black powder: Large-sized cobalt-containing waste lithium batteries after draining are disassembled, the battery shells are removed, and low-temperature pyrolysis is carried out at 500℃~700℃ for 1h~2h to remove materials with no recycling value; Graphite powder and iron filings are removed by flotation, magnetic separation and sieving, taking advantage of the differences in powder density, magnetic properties and particle size after physical crushing, and high-purity copper filings, aluminum filings and cathode black powder are obtained.

[0015] S2.2 Preparation of alloy powder: The drained small-sized cobalt-containing waste lithium batteries are put into a high-temperature furnace for roasting. Under the conditions of air isolation, protective atmosphere or negative pressure, the roasting temperature is 1000℃~1200℃ and the temperature is held for 1h~4h. The graphite contained in the cobalt-containing waste lithium batteries is used to modify the nickel, cobalt and manganese compounds, reduce the compounds to alloys, and use physical crushing to crush the alloys into alloy powders of less than 10 mesh.

[0016] It should be noted that the ammonia gas obtained in step S5 can be absorbed by water to obtain ammonia water, which can then be reused in step S4.

[0017] It should be noted that the cobalt-containing waste lithium batteries are lithium cobalt oxide batteries and ternary lithium batteries.

[0018] It should be noted that the large-size cobalt-containing waste lithium battery is a power lithium battery, and the small-size cobalt-containing waste lithium battery is a 3C lithium battery.

[0019] It should be noted that the dilute acid in step S3 is dilute sulfuric acid.

[0020] It should be noted that the leaching process in step S3 has the following parameters: pH 1.5 to 2.0, temperature 60°C to 90°C, time 2 hours to 5 hours, and stirring speed 50 r / min to 200 r / min.

[0021] It should be noted that the temperature is 70℃~80℃, the time is 3h~4h, and the stirring speed is 60r / min~120r / min.

[0022] It should be noted that the Fe, Al, and Cu contents of the filtrate obtained in step S4 are all less than 1 mg / L.

[0023] The beneficial effects of this invention are as follows:

[0024] 1. Low-acid leaching is used. The 0-valence alloy powder mainly reacts with the high-valence cathode black powder (mainly metal oxides). Only a small amount of alloy powder reacts with acid, resulting in low hydrogen production. This avoids the safety hazard of generating a large amount of hydrogen when leaching alloy powder with acid after obtaining it in the pyrometallurgical recycling of waste lithium batteries.

[0025] 2. The self-immersion process uses alloy powder and positive electrode black powder as reducing agent and oxidizing agent respectively, eliminating the need to add oxidizing agent and reducing reducing agent, saving auxiliary materials and reducing leaching cost.

[0026] 3. The self-immersion process only adds sulfuric acid, which avoids the hazards of SO2 and other gases generated when adding reducing agents during the leaching process of waste lithium batteries in wet recycling.

[0027] 4. The leaching rates of nickel, cobalt, manganese, copper and lithium exceed 99%. The copper and aluminum shavings obtained in step (b) are of high purity and can be sold directly, with a recovery rate of over 92%. Detailed Implementation

[0028] The present invention will be further described below. It should be noted that this embodiment is based on the present technical solution and provides detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to this embodiment.

[0029] Example 1

[0030] This invention relates to a method for homogeneous modification and complementary leaching of cobalt-containing waste lithium batteries, the method comprising the following steps:

[0031] S1 Discharge: Put the cobalt-containing waste lithium battery into a discharge battery containing a sodium salt solution of NaCl and / or Na2SO4, discharge for 24h to 48h, drain, and the drained water is reused in the discharge battery.

[0032] S2 Preparation of cathode black powder and alloy powder: The discharged cobalt-containing waste lithium batteries are divided into two parts according to their size. The large-sized cobalt-containing waste lithium batteries are used to prepare cathode black powder, and the small-sized cobalt-containing waste lithium batteries are used to prepare alloy powder.

[0033] S3 complementary leaching: The obtained positive electrode black powder and alloy powder are mixed according to the principle of electron gain and loss balance, and the weight ratio of the two is 1:1 to 3:1. The mixture is then leached in dilute acid.

[0034] S4 Copper, Iron and Aluminum Removal: After leaching, add ammonium bicarbonate or ammonia to adjust the pH to 2.5-3, add ammonium sulfide to precipitate Cu and separate solid and liquid, and recover copper sulfide slag; add ammonium bicarbonate or ammonia to the filtrate to raise the pH to 5-6, precipitate Fe and Al and separate solid and liquid, to obtain impurity-removed filtrate and iron and aluminum slag;

[0035] S5 Preparation of ternary hydroxide: The filtrate containing Mn, Co, Ni and Li obtained in step S4 is supplemented with an appropriate amount of one or two of Mn salt, Co salt and Ni salt as needed; NaOH solution and ammonia water are added in an inert atmosphere at 45℃~55℃ for co-precipitation, and nickel-cobalt-manganese ternary hydroxide and co-precipitated liquid are obtained after solid-liquid separation;

[0036] S6 Ammonia stripping: The co-precipitated liquid obtained in step S5 is heated with steam to strip ammonia, resulting in a stripped liquid and ammonia gas.

[0037] S7 Lithium precipitation: Add a carbonate solution to the liquid obtained after ammonia stripping in step S6 to precipitate lithium, and obtain lithium carbonate.

[0038] Furthermore, step S2 of the present invention further includes:

[0039] S2.1 Preparation of cathode black powder: Large-sized cobalt-containing waste lithium batteries after draining are disassembled, the battery shells are removed, and low-temperature pyrolysis is carried out at 500℃~700℃ for 1h~2h to remove materials with no recycling value; Graphite powder and iron filings are removed by flotation, magnetic separation and sieving, taking advantage of the differences in powder density, magnetic properties and particle size after physical crushing, and high-purity copper filings, aluminum filings and cathode black powder are obtained.

[0040] S2.2 Preparation of alloy powder: The drained small-sized cobalt-containing waste lithium batteries are put into a high-temperature furnace for roasting. Under the conditions of air isolation, protective atmosphere or negative pressure, the roasting temperature is 1000℃~1200℃ and the temperature is held for 1h~4h. The graphite contained in the cobalt-containing waste lithium batteries is used to modify the nickel, cobalt and manganese compounds, reduce the compounds to alloys, and use physical crushing to crush the alloys into alloy powders of less than 10 mesh.

[0041] It is worth noting that in the implementation steps of the present invention, the alloy powder preparation process in step S2.2 not only decomposes and volatilizes substances with no recycling value such as binders, separators, and electrolytes in the battery cell, but also causes a reaction in which metal compounds are reduced by carbon, 2MeO+C=Me+CO2↑, or MeO+C=Me+CO↑.

[0042] On the other hand, in step S3, the reducing properties of the alloy and the oxidizing properties of the cathode black powder are mainly utilized to react directly under acidic conditions, generating soluble low-valence metal ions, such as Co. 2+ Ni 2+ Mn 2+ Cu 2+ Etc. Because some battery casings are made of iron, and the complementary leaching system contains a small amount of iron, iron reacts under acidic conditions as Fe. 2+ Fe 3+ The state exists in solution, and as an electron transfer medium, it accelerates the solid-solid redox reaction between the cathode black powder and the alloy powder, thereby increasing the leaching rate.

[0043] Furthermore, the ammonia gas obtained in step S5 of the present invention can be absorbed by water to obtain ammonia water, and the obtained ammonia water can be reused in step S4.

[0044] Furthermore, the cobalt-containing waste lithium battery described in this invention is a lithium cobalt oxide battery or a ternary lithium battery.

[0045] Furthermore, the large-size cobalt-containing waste lithium battery of the present invention is a power lithium battery, and the small-size cobalt-containing waste lithium battery is a 3C lithium battery.

[0046] Furthermore, in step S3 of the present invention, the dilute acid is dilute sulfuric acid.

[0047] Furthermore, the leaching process in step S3 of the present invention has the following process parameters: pH 1.5 to 2.0, temperature 60°C to 90°C, time 1 h to 4 h, and stirring speed 50 r / min to 200 r / min.

[0048] Furthermore, the temperature is 70℃~80℃, the time is 3h~4h, and the stirring speed is 60r / min~120r / min.

[0049] Furthermore, the impurity-removed filtrate obtained in step S4 of the present invention has Fe, Al, and Cu contents of less than 1 mg / L.

[0050] Examples 2-5:

[0051] The process flow is the same as in Example 1, but the process parameters are adjusted. The process parameters and implementation effects of Examples 1 to 5 are shown in the table below.

[0052]

[0053] As can be seen from the process parameters and results of Examples 1-5, the present invention obtains two materials with oxidizing and reducing properties respectively from cobalt-containing waste lithium batteries through different methods. These two materials are then mixed and acid is added for complementary leaching, avoiding the addition of reducing and oxidizing agents, and the generation of SO2 and NO. x The elimination of the hazards of gases saves on leaching costs and significantly reduces the safety risks of H2 generation during pyrometallurgical recovery. It also has the advantage of high recovery rate of valuable metals.

[0054] For those skilled in the art, various other corresponding changes and modifications can be made based on the technical solutions and concepts described above, and all such changes and modifications should fall within the protection scope of the claims of this invention.

Claims

1. A method for homogeneous modification and complementary leaching of cobalt-containing waste lithium batteries, characterized in that, The method includes the following steps: S1 Discharge: Immerse the cobalt-containing waste lithium battery in a discharge battery containing a sodium salt solution of NaCl and / or Na2SO4, discharge for 24h to 48h, drain, and reuse the drained water in the discharge battery. S2 Preparation of cathode black powder and alloy powder: The discharged cobalt-containing waste lithium batteries are divided into two parts according to their size. The large-sized cobalt-containing waste lithium batteries are used to prepare cathode black powder, and the small-sized cobalt-containing waste lithium batteries are used to prepare alloy powder. S3 Complementary Leaching: The obtained positive electrode black powder and alloy powder are mixed according to the principle of electron gain and loss balance, and the weight ratio of the two is 1:1 to 3:

1. The mixture is then leached in dilute acid. S4 Removal of Copper, Iron and Aluminum: After leaching, add ammonium bicarbonate or ammonia to adjust the pH to 2.5-3, add ammonium sulfide to precipitate Cu and separate solid and liquid, and recover copper sulfide slag; add ammonium bicarbonate or ammonia to the filtrate to raise the pH to 5-6, precipitate Fe and Al and separate solid and liquid, and obtain impurity-removed filtrate and iron and aluminum slag. S5 Preparation of ternary hydroxide: The filtrate containing Mn, Co, Ni and Li obtained in step S4 is supplemented with an appropriate amount of one or two of Mn salt, Co salt and Ni salt as needed; NaOH solution and ammonia water are added in an inert atmosphere at 45℃~55℃ for co-precipitation, and nickel-cobalt-manganese ternary hydroxide and co-precipitated liquid are obtained after solid-liquid separation; S6 Ammonia stripping: The co-precipitated liquid obtained in step S5 is heated with steam to strip ammonia, resulting in a stripped liquid and ammonia gas. S7 Lithium precipitation: Add a carbonate solution to the ammonia stripping liquid obtained in step S6 to precipitate lithium, and obtain lithium carbonate. Step S2 further includes: S2.1 Preparation of cathode black powder: The large-sized cobalt-containing waste lithium batteries after draining are disassembled. After removing the battery shell, they are subjected to low-temperature pyrolysis at 500℃~700℃ and kept at this temperature for 1h~2h to remove materials with no recycling value. Utilizing the differences in powder density, magnetic properties and particle size after physical crushing, graphite powder and iron filings are removed by flotation, magnetic separation and sieving to separate copper filings, aluminum filings and cathode black powder with high purity. S2.2 Preparation of alloy powder: The drained small-sized cobalt-containing waste lithium batteries are put into a high-temperature furnace for roasting. Under the conditions of isolation from air, protective atmosphere or negative pressure, the roasting temperature is 1000℃~1200℃ and the temperature is held for 1h~4h. The graphite contained in the cobalt-containing waste lithium batteries is used to modify the nickel, cobalt and manganese compounds, reduce the compounds to alloys, and crush the alloys into alloy powder with a physical crushing method. The large-sized cobalt-containing waste lithium battery is a power lithium battery, and the small-sized cobalt-containing waste lithium battery is a 3C lithium battery.

2. The method for homogeneous modification and complementary leaching of cobalt-containing waste lithium batteries according to claim 1, characterized in that, The ammonia gas obtained in step S5 can be absorbed by water to obtain ammonia water, which can then be reused in step S4.

3. The method for homogeneous modification and complementary leaching of cobalt-containing waste lithium batteries according to claim 1, characterized in that, The cobalt-containing waste lithium batteries are lithium cobalt oxide batteries and ternary lithium batteries.

4. The method for homogeneous modification and complementary leaching of cobalt-containing waste lithium batteries according to claim 1, characterized in that, The dilute acid in step S3 is dilute sulfuric acid.

5. The method for homogeneous modification and complementary leaching of cobalt-containing waste lithium batteries according to claim 1, characterized in that, The leaching process in step S3 has the following parameters: pH 1.5–2.0, temperature 60°C–90°C, time 2–5 h, and stirring speed 50 r / min–200 r / min.

6. The method for homogeneous modification and complementary leaching of cobalt-containing waste lithium batteries according to claim 5, characterized in that, The temperature is 70℃~80℃, the time is 3h~4h, and the stirring speed is 60r / min~120r / min.

7. The method for homogeneous modification and complementary leaching of cobalt-containing waste lithium batteries according to claim 1, characterized in that, The impurity-removed filtrate obtained in step S4 has Fe, Al, and Cu contents of less than 1 mg / L.

Images