Method for recovering nickel and cobalt metals in ternary lithium battery by using nitrate-liquid ammonia solution

Abstract

The invention discloses a method for recovering nickel and cobalt metals in a ternary lithium battery by using a nitrate-liquid ammonia solution, and belongs to the field of waste battery recovery and electrochemical metallurgy. The method comprises the following steps: leaching black powder of the waste ternary lithium battery by using a mixture of nitric acid and hydrogen peroxide, and then carrying out solid-liquid separation; the leaching liquid is subjected to impurity removal, extraction and back extraction, and a high-purity nickel / cobalt nitrate solution is obtained; evaporating, concentrating, crystallizing and drying the nickel / cobalt nitrate solution to obtain dried nickel / cobalt nitrate salt; uniformly mixing liquid ammonia, the dried nickel nitrate / cobalt salt and an additive, and removing water through a water removal agent to obtain a nitrate-liquid ammonia solution with low water content as an electrolyte; the polished cathode and anode are immersed in nitrate-liquid ammonia electrolyte, and nickel or cobalt is electrically deposited on the cathode at a certain temperature and current density; and cleaning the cathode to obtain a nickel or cobalt deposition layer with metallic luster, and stripping to obtain metallic nickel or metallic cobalt. According to the method, nickel-cobalt metal in the ternary lithium battery can be recycled in a nitric acid system in a short process.

Description

Technical Field

[0001] This invention belongs to the field of waste battery recycling and electrochemical metallurgy technology, and particularly relates to a method for recovering nickel and cobalt metal from ternary lithium batteries using nitrate-liquid ammonia solution. Background Technology

[0002] As new energy vehicles enter their large-scale retirement phase, the number of used ternary lithium-ion batteries is exploding. The efficient recycling of high-value metals such as nickel, cobalt, manganese, and lithium from these batteries is of significant economic and environmental importance for ensuring strategic resource security and reducing the environmental burden of primary mineral extraction.

[0003] Currently, wet recovery is the mainstream process in the industry, and its typical route is "sulfuric acid ( ) + hydrogen peroxide The process involves leaching with nitric acid (N), followed by solvent extraction to separate the metal. However, this system typically achieves a leaching rate of around 90% for valuable metals, leaving room for improvement. In recent years, nitric acid (N) has been used in leaching... ) + hydrogen peroxide Leaching offers the potential for extremely high leaching rates exceeding 99%, and the acquisition of high-purity nickel / cobalt solutions through extraction. However, it faces a critical bottleneck in producing high-value nickel-cobalt metal products: existing mature electrolytic deposition equipment is only compatible with sulfate or chloride systems. Therefore, nitric acid leaching solutions must undergo a lengthy and energy-intensive "sulfation / chlorination" conversion step (typically involving pH adjustment to generate nickel-cobalt hydroxides, followed by dissolution with sulfuric or hydrochloric acid), which increases process complexity and acid / alkali consumption. Direct use of nitrate-aqueous solution electrolysis not only results in poor product quality but also leads to severe equipment corrosion and the production of toxic nitrogen oxides as cathode byproducts. Issues such as generation.

[0004] Liquid ammonia has excellent solubility for nitrates and can directly dissolve nitric acid leachate, completely eliminating the intermediate step of conversion to sulfate / chloride. Simultaneously, electrowinning metals produced in liquid ammonia significantly reduces equipment corrosion and fundamentally avoids NO pollution. x The generation of byproducts. Therefore, a more streamlined, greener, and more efficient new path for recycling ternary lithium batteries can be constructed using the nitric acid leaching system: "Waste ternary lithium battery black powder → Nitric acid leaching → Extraction, separation, and purification → Nitrate-liquid ammonia solution electrowinning → Nickel-cobalt metal". This shorter process not only has the potential to reduce overall energy and material consumption but also aligns with the development direction of green metallurgy, providing a promising technological option for large-scale, high-efficiency battery recycling in the future. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for recovering nickel-cobalt metal from ternary lithium batteries using a nitrate-liquid ammonia solution. This method eliminates the sulfate / chloride conversion step, directly obtaining high-purity nickel-cobalt metal from nickel-cobalt nitrates; and does not generate acid mist or NO. x It can achieve a simplified, green and efficient recycling process of "waste ternary lithium battery black powder → nitric acid leaching → extraction separation and purification → liquid ammonia solution electrowinning → nickel and cobalt metal".

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] This invention discloses a method for recovering nickel and cobalt metal from ternary lithium batteries using a nitrate-liquid ammonia solution, comprising the following steps:

[0008] Step 1: After leaching the waste ternary lithium battery black powder with a mixture of nitric acid and hydrogen peroxide, solid-liquid separation is performed. The leaching liquid is then purified, extracted, and back-extracted to obtain a high-purity nickel nitrate or cobalt nitrate solution. The high-purity nickel nitrate / cobalt nitrate solution is evaporated, concentrated, crystallized, and further dried to obtain dried nickel nitrate or cobalt nitrate. Liquid ammonia, dried nickel nitrate / cobalt nitrate, and additives are uniformly mixed and dehydrated with a dehydrating agent to obtain a low-water-content nitrate-liquid ammonia solution as the electrolyte.

[0009] Step 2: Immerse the polished cathode and anode in nitrate-liquid ammonia electrolyte. At a certain temperature and current density, deposit nickel or cobalt onto the cathode through electrodeposition. After cleaning the cathode, a nickel or cobalt deposit with a metallic luster is obtained. After peeling, it becomes metallic nickel or metallic cobalt.

[0010] The stripping agent in step one is a nitric acid solution.

[0011] The drying conditions in step one refer to a drying temperature of 60~150 °C, a pressure of -0.1~0.1 MPa, and a duration of 6~96 hours;

[0012] The additive in step one is one or more of potassium nitrate, sodium nitrate, ammonium nitrate, ammonium iodide, and potassium iodide.

[0013] In step one, the amounts of liquid ammonia, nitrate, and additives added are such that the solid-liquid ratio of nickel / cobalt nitrate to liquid ammonia after drying is > 3 g / L; and the solid-liquid ratio of additives to liquid ammonia is 0.1~30 g / L.

[0014] The dehydrating agent in step one is one or more of calcium oxide, calcium chloride, silica gel, montmorillonite, and metallic sodium.

[0015] In step one, the low-water-content nitrate-liquid ammonia electrolyte refers to a liquid ammonia solution in which the mass percentage of water is less than 1 wt.%.

[0016] In step two, the cathode substrate material is one of titanium, stainless steel, copper, cobalt, or nickel. The anode substrate material is one of platinum, nickel, cobalt, graphite carbon, nickel alloy, titanium-coated lead dioxide, or titanium-coated iridium dioxide. The anode-cathode spacing is 0.5 to 5 cm, and the anode-cathode area ratio is 1:0.25 to 4.

[0017] In step two, the temperature is -70 ~ 25 °C, and the current density is 10 ~ 300 A / m. 2 Electrowinning is performed under certain conditions.

[0018] In step two, the solvent of the cleaning solution is one or more of deionized water, acetone, and anhydrous ethanol, and the solute is one or more of oxalic acid, sulfuric acid, hydrochloric acid, citric acid, and carbonic acid. The solid-liquid ratio of the solute to the solvent is 0.5 to 50 g / L.

[0019] Beneficial effects:

[0020] 1. This invention discloses a method for recovering nickel / cobalt metal from ternary lithium batteries using a nitrate-liquid ammonia solution. This method eliminates the sulfate / chloride conversion step, directly obtaining nickel / cobalt metal by electrowinning using nitrate as the solute.

[0021] 2. The present invention discloses a method for recovering nickel and cobalt metals from ternary lithium batteries using a nitrate-liquid ammonia solution. The method employs a non-aqueous nitrate-liquid ammonia electrolyte with nickel nitrate or cobalt nitrate as the solute and liquid ammonia as the solvent for electrodeposition, thereby avoiding the problems of poor product quality, strong corrosiveness of nitric acid, and cathode byproduct pollution present in the nitrate-aqueous solution system.

[0022] 5. The present invention discloses a method for recovering nickel and cobalt metals from ternary lithium batteries using a nitrate-liquid ammonia solution, which realizes the electrochemical extraction of high-purity nickel / cobalt metals in a non-aqueous nitrate-liquid ammonia solution. Attached Figure Description

[0023] Figure 1 This is a flowchart of a method for recovering nickel and cobalt metal from ternary lithium batteries using a nitrate-liquid ammonia solution according to the present invention.

[0024] Figure 2 This is a photograph of the electrolytic cobalt product from Example 1.

[0025] Figure 3 This is a photograph of the electrolytic nickel product from Example 3.

[0026] Figure 4 This is a photograph of the electrolytic cobalt product from Comparative Example 3.

[0027] Figure 5 The cathode results are for Comparative Example 4, cobalt nitrate-aqueous solution. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, see [link to relevant documentation]. Figure 1 The present invention will be further described in detail below with reference to the following embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0029] Example 1:

[0030] Step (1): The waste ternary lithium battery black powder is leached with a mixed solution of nitric acid and hydrogen peroxide. After impurity removal, the leachate is extracted with extractants such as Cynex 272 (bis(2,4,4-trimethylpentyl)phosphonic acid), and then back-extracted with nitric acid solution to obtain a high-purity cobalt nitrate solution. The high-purity cobalt nitrate solution is evaporated, concentrated and crystallized, and then dried at 100 °C and -0.1 MPa for 36 hours to obtain dried cobalt nitrate. 75 mL of liquid ammonia, 1.5 g of dried cobalt nitrate and 0.05 g of ammonia nitrate are mixed evenly in an electrolytic cell, and water is removed with 1 g of calcium oxide to obtain a cobalt nitrate-liquid ammonia electrolyte.

[0031] Step (2): The copper and cobalt sheets are polished to a bright finish using sandpaper of different mesh sizes (100~10000 mesh), then treated with anhydrous ethanol and dried to serve as the cathode and anode, respectively, and inserted into the cobalt nitrate-liquid ammonia electrolyte. The electrode spacing is 1 cm, and the anode-cathode area ratio is 1:2; the temperature is -34°C, and the current density is 100 A / m. 2 Electrowinning under certain conditions for 90 min yielded a cathode deposit. After removing the cathode sample, it was washed sequentially with 5 g / L oxalic acid-anhydrous ethanol solution and deionized water, dried, and then peeled off to obtain metallic cobalt.

[0032] The ICP results of the obtained cobalt metallic product are as follows:

[0033]

[0034] Example 2:

[0035] Step (1): Waste ternary lithium battery black powder is leached with a mixed solution of nitric acid and hydrogen peroxide. After impurity removal, the leachate is extracted with an extractant such as P507 (di(2-ethylhexyl)phosphonic acid), and then back-extracted with nitric acid solution to obtain a high-purity cobalt nitrate solution. The high-purity cobalt nitrate solution is evaporated, concentrated and crystallized, and then dried at 130 °C and -0.1 MPa for 12 hours to obtain dried cobalt nitrate. 100 mL of liquid ammonia and 1.0 g of dried cobalt nitrate are uniformly mixed, and 1 g of calcium oxide is used to remove water to obtain a cobalt nitrate-liquid ammonia electrolyte.

[0036] Step (2): The copper sheet and graphite carbon sheet are polished to a bright finish using sandpaper of different mesh sizes (100~10000 mesh), then treated with anhydrous ethanol and dried to serve as the cathode and anode, respectively, and inserted into the cobalt nitrate-liquid ammonia electrolyte. The electrode spacing is 1.2 cm, and the anode-cathode area ratio is 1:1; the temperature is 0°C, and the current density is 50 A / m. 2 Under the given conditions, a cathode deposit was obtained by electrodeposition for 60 min. After recovering the liquid ammonia, the cathode sample was removed and washed sequentially with 5 g / L oxalic acid-deionized water. After drying, it was peeled off to obtain metallic cobalt.

[0037] The ICP results of the obtained cobalt metallic product are as follows:

[0038]

[0039] Example 3:

[0040] Step (1): Waste ternary lithium battery black powder is leached with a mixed solution of nitric acid and hydrogen peroxide. After impurity removal, the leachate is extracted with extractants such as Cynex 272 (bis(2,4,4-trimethylpentyl)phosphonic acid), and then back-extracted with nitric acid solution to obtain a high-purity nickel nitrate solution. The high-purity nickel nitrate solution is evaporated, concentrated and crystallized, and then dried at 120 °C and atmospheric pressure for 36 hours to obtain dried nickel nitrate. 80 mL of liquid ammonia and 1 g of dried nickel nitrate are mixed evenly, and water is removed with 1 g of calcium oxide to obtain a nickel nitrate-liquid ammonia electrolyte.

[0041] Step (2): The copper sheet and graphite carbon sheet are polished to a bright finish using sandpaper of different mesh sizes (100~10000 mesh), then treated with anhydrous ethanol and dried to serve as the cathode and anode, respectively, and inserted into the cobalt nitrate-liquid ammonia electrolyte. The electrode spacing is 0.5 cm, and the anode-cathode area ratio is 1:2; the temperature is -34°C, and the current density is 75 A / m. 2 Under the given conditions, electrodeposition for 60 min yielded a cathode deposit. After recovering the liquid ammonia, the cathode sample was removed and washed sequentially with a 10 g / L citric acid-anhydrous ethanol solution and deionized water. After drying, it was peeled off to obtain metallic nickel.

[0042] The ICP results of the obtained cobalt metallic product are as follows:

[0043]

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0045] Comparative Example

[0046] Comparative Example 1:

[0047] Unlike Example 1, the stripping agent in step (1) is a sulfuric acid solution, and the resulting cobalt sulfate-liquid ammonia solution is the electrolyte, while the other conditions are the same.

[0048] Unlike Example 1, under these conditions, cobalt sulfate is essentially insoluble, and there are no obvious electrodeposition products at the cathode.

[0049] Comparative Example 2:

[0050] Unlike Example 1, the stripping agent in step (1) is hydrochloric acid solution, and the electrolyte is cobalt chloride-liquid ammonia solution. All other conditions are the same.

[0051] Unlike Example 1, under these conditions, cobalt chloride is essentially insoluble, and there are no obvious electrodeposition products at the cathode.

[0052] Comparative Example 3:

[0053] Unlike Example 1, the cobalt nitrate component in step (1) is Co(NO3)2·6H2O, while all other conditions are the same.

[0054] Unlike Example 1, the cobalt nitrate-liquid ammonia electrolyte under these conditions has a water content greater than 1 wt.% in the liquid ammonia, and its electrowinning product is black.

[0055] Comparative Example 4:

[0056] Unlike Example 1, the solvent used in step (1) is water, while all other conditions are the same.

[0057] Unlike Example 1, under these conditions no metallic products are deposited at the cathode, and a dark green substance is formed near the cathode.

[0058] Comparative Example 5:

[0059] Unlike Example 1, the current density in step (2) is 300 A / m. 2 All other conditions are the same.

[0060] Unlike Example 1, when using this current density for electrodeposition, the electrodeposition products are prone to detachment, and some products are black.

[0061] Comparative Example 6:

[0062] Unlike Example 2, the interpole spacing in step (2) is 6.0 cm, while all other conditions are the same.

[0063] Unlike Example 2, the electrodeposition operation using this electrode spacing produces a black electrodeposition product.

[0064] Comparative Example 7:

[0065] Unlike Example 3, in step (2), the cathode sample was washed directly with deionized water after being taken out, while all other conditions were the same.

[0066] Unlike Example 3, the cathode surface after being washed directly with deionized water will have hydroxide, additives or salt residues.

[0067] Comparative Example 8:

[0068] Unlike Example 3, the stripping agent in step (1) is sulfuric acid solution, and the electrolyte is nickel sulfate-liquid ammonia solution. All other conditions are the same.

[0069] Unlike Example 3, under these conditions, nickel sulfate is essentially insoluble, and there are no obvious electrodeposition products at the cathode.

[0070] Comparative Example 9:

[0071] Unlike Example 3, the stripping agent in step (1) is hydrochloric acid solution, and the electrolyte is nickel chloride-liquid ammonia solution. All other conditions are the same.

[0072] Unlike Example 3, nickel chloride is essentially insoluble under these conditions, and there are no obvious electrodeposition products at the cathode.

[0073] The above detailed description further illustrates the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for recovering nickel-cobalt metal from ternary lithium batteries using a nitrate-liquid ammonia solution, characterized in that: Includes the following steps: Step 1: After leaching the waste ternary lithium battery black powder with a mixture of nitric acid and hydrogen peroxide, solid-liquid separation is performed. The leaching liquid is then purified, extracted, and back-extracted to obtain a high-purity nickel nitrate or cobalt nitrate solution. The high-purity nickel nitrate / cobalt nitrate solution is evaporated, concentrated, crystallized, and further dried to obtain dried nickel nitrate or cobalt nitrate. Liquid ammonia, dried nickel nitrate / cobalt nitrate, and additives are uniformly mixed and dehydrated with a dehydrating agent to obtain a low-water-content nitrate-liquid ammonia solution as the electrolyte. Step 2: Immerse the polished cathode and anode in nitrate-liquid ammonia electrolyte. At a certain temperature and current density, deposit nickel or cobalt onto the cathode through electrodeposition. After cleaning the cathode, a nickel or cobalt deposit with a metallic luster is obtained. After peeling, it becomes metallic nickel or metallic cobalt.

2. The method as described in claim 1, characterized in that: The stripping agent in step one is a nitric acid solution.

3. The method as described in claim 1, characterized in that: The drying conditions in step one refer to a drying temperature of 60~150 °C, a pressure of -0.1~0.1 MPa, and a duration of 6~96 hours.

4. The method as described in claim 1, characterized in that: The additive in step one is one or more of potassium nitrate, sodium nitrate, ammonium nitrate, ammonium iodide, and potassium iodide.

5. The method as described in claim 1, characterized in that: In step one, the amounts of liquid ammonia, nitrate, and additives added are such that the solid-liquid ratio of nickel / cobalt nitrate to liquid ammonia after drying is > 3 g / L; and the solid-liquid ratio of additives to liquid ammonia is 0.1~30 g / L.

6. The method as described in claim 1, characterized in that: The dehydrating agent in step one is one or more of calcium oxide, calcium chloride, silica gel, montmorillonite, and metallic sodium.

7. The method as described in claim 1, characterized in that: In step one, the low-water-content nitrate-liquid ammonia electrolyte refers to a liquid ammonia solution in which the mass percentage of water is less than 1 wt.%.

8. The method as described in claim 1, characterized in that: In step two, the cathode substrate material is one of titanium sheet, stainless steel sheet, copper sheet, cobalt sheet or nickel sheet; the anode substrate material is one of platinum sheet, nickel sheet, cobalt sheet, graphite carbon sheet, nickel alloy sheet, titanium-coated lead dioxide plate or titanium-coated iridium dioxide plate; the anode-cathode spacing is 0.5 ~ 5 cm, and the anode-cathode area ratio is 1:0.25~4.

9. The method as described in claim 1, characterized in that: In step two, the temperature is -70 ~ 25 °C, and the current density is 10 ~ 300 A / m. 2 Electrowinning is performed under certain conditions.

10. The method as described in claim 1, characterized in that: In step two, the solvent of the cleaning solution is one or more of deionized water, acetone, and anhydrous ethanol, and the solute is one or more of oxalic acid, sulfuric acid, hydrochloric acid, citric acid, and carbonic acid. The solid-liquid ratio of the solute to the solvent is 0.5 ~ 50 g / L.

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