Full-chain integrated method for recovering nickel and cobalt from waste ternary battery powders

Abstract

The present disclosure relates to the technical field of recovery of waste ternary power batteries, and provides a full-chain integrated method for recovering nickel and cobalt from waste ternary battery powders. In the present disclosure, roasted battery powders and unroasted battery powders are mixed and pressurized for synergistic leaching, wherein since the roasted battery powders have certain reducibility, the utilization of H2O2 during an acid leaching process can be omitted, and therefore the valuable metal elements of nickel, cobalt, manganese and lithium in the waste ternary battery powders can be efficiently extracted without consuming a reducing agent, the leaching rate is improved, and the generation of hydrogen can also be avoided; and a buffer solution consisting of Mg(OH)2 and MgSO4 is then used for precipitating valuable metals, and therefore the solution can be ensured to have a stable pH, which is maintained within a stable pH range, and the growth speed of nickel-cobalt hydroxide particles is slowed down at the same time, thereby greatly improving the product purity and obtaining a product having a low water content and large particles.

Description

A fully integrated method for recovering nickel and cobalt from waste ternary battery powder Technical Field

[0001] The present disclosure relates to the technical field of recycling waste ternary power batteries, and in particular to a full-chain integrated method for recycling nickel and cobalt from waste ternary battery powder. Background Art

[0002] With the rapid development of new energy electric vehicles in recent years, and the fact that lithium-ion batteries typically reach end-of-life after 5-8 years of use, the stockpile of used batteries is steadily increasing. Heavy metals in used batteries pose a significant environmental risk, and their concentrations of rare and precious metals, such as nickel, cobalt, manganese, and lithium, are extremely high, far exceeding those found in common ores, making them a typical "urban ore." Therefore, comprehensive recycling of used batteries not only offers high economic value but also contributes to ecological and environmental protection.

[0003] At present, the main methods used in the wet recycling process of waste ternary lithium batteries are inorganic acid leaching, organic acid leaching, and biological leaching. Among them, the biological leaching method has low cost, low energy consumption, no pollution, and a relatively simple process flow, but the leaching cycle is long, the leaching conditions are difficult to control, and it is still in the laboratory research stage. Organic acid leaching mainly uses oxalic acid, citric acid, and malic acid, and is mainly used in university research, with low prospects for industrial application. For inorganic acid leaching processes, hydrochloric acid, phosphoric acid, sulfuric acid, etc. are mainly used as the main leaching agents, among which the H2SO4+H2O2 leaching system is the most common, but H2O2 is expensive, easy to decompose, has low utilization rate, and requires high storage conditions. It is a flammable and explosive product and has certain constraints in industrial production. At the same time, the amount of sulfuric acid used is large.

[0004] Existing wet recycling processes for used batteries typically separate metal ions from leachate using alkaline substances such as quicklime, sodium carbonate, and sodium hydroxide to adjust the solution pH and thereby precipitate the metal ions. However, this method often suffers from "localized over-alkalinity," resulting in products with high impurity content, high moisture content, and low metal content. Furthermore, this method consumes a large amount of alkali, leading to high production costs.

[0005] In view of this, the present disclosure is proposed.

[0006] Summary of the Invention

[0007] The purpose of the present disclosure is to provide a full-chain integrated method for recovering nickel and cobalt from waste ternary battery powder, which can realize the efficient extraction of nickel, cobalt, manganese and lithium metal elements without reducing agents, and at the same time, the nickel and cobalt hydroxide products have low water content and high purity.

[0008] The present disclosure is achieved as follows:

[0009] In a first aspect, the present disclosure provides a fully integrated process for recovering nickel and cobalt from waste ternary battery powder, comprising:

[0010] Mixing and slurrying: mixing the calcined battery powder and the uncalcined battery powder to obtain slurry;

[0011] Pressure leaching: mixing the slurry with acid and leaching under pressure, separating the solid and liquid after leaching to obtain pressure leaching liquid and pressure leaching residue;

[0012] Precipitation and impurity removal: after mixing the pressurized leaching solution with an oxidant, adjusting the solution pH to 4.5-6.0 to remove impurities such as iron, aluminum, and silicon, and separating the solid and liquid after impurity removal to obtain impurity-removed slag and impurity-removed liquid;

[0013] One-stage hydrolysis precipitation: the impurity-removed liquid is mixed with a buffer solution composed of Mg(OH)2 and MgSO4 to precipitate nickel ions and cobalt ions, wherein the solid content of magnesium hydroxide in the buffer solution is 1%-40%, and the solid content of Mg(OH)2 is 1%-40%. 2+ The concentration is 5-45g / L, and solid-liquid separation is performed to obtain the product nickel cobalt hydroxide and a post-precipitation liquid.

[0014] In an optional embodiment, the mass ratio of the calcined battery powder to the uncalcined battery powder is 1:5-20.

[0015] In an optional embodiment, during the pulping process, the solid-liquid ratio is 3-5:1.

[0016] In an optional embodiment, the solvent used in the slurrying is water.

[0017] In an optional embodiment, the calcined battery powder is obtained by placing battery black powder of waste ternary batteries in a tube furnace and calcining it at 500-1500° C. for 1-3 hours.

[0018] In an optional embodiment, the mixing and slurrying further includes ball milling and activating the slurry.

[0019] In an optional embodiment, the ball milling activation time is 30-90 minutes.

[0020] In an optional embodiment, in the pressure leaching step, the reaction pressure is 0.3-3.0 MPa.

[0021] In an optional embodiment, in the pressure leaching step, the reaction temperature is 150-250°C.

[0022] In an optional embodiment, in the pressure leaching step, the leaching time is 0.5-3.0 hours.

[0023] In an optional embodiment, in the pressure leaching step, the acid added is sulfuric acid, the amount of sulfuric acid added is 80%-200% of the theoretical sulfuric acid consumption for leaching all metals in the slurry, and the liquid-to-solid ratio of the sulfuric acid to the slurry is 2-4:1.

[0024] In an optional embodiment, the oxidant includes at least one of hydrogen peroxide, manganese dioxide and chlorine.

[0025] In an optional embodiment, the amount of the oxidant added is 1-2% of the volume of the pressure leachate.

[0026] In an optional embodiment, in the precipitation and impurity removal step, a first alkaline substance is used to adjust the pH value of the solution, and the first alkaline substance includes at least one of limestone, sodium carbonate and calcium oxide.

[0027] In an optional embodiment, the mixing and stirring time in the hydrolysis and precipitation step is 1-3 hours.

[0028] In an optional embodiment, after the first-stage hydrolysis precipitation, a second-stage hydrolysis precipitation is further included: the first-stage precipitation liquid is mixed with a second alkaline substance to adjust the pH value of the system to 7.0-9.0, and a second-stage hydrolysis precipitation is performed to completely precipitate nickel ions, cobalt ions and manganese ions, and solid-liquid separation is performed to obtain an intermediate product nickel cobalt hydroxide and the second-stage precipitation liquid.

[0029] In an optional embodiment, the second alkaline substance includes at least one of lime milk, sodium carbonate and sodium hydroxide.

[0030] In an optional embodiment, the intermediate product nickel cobalt hydroxide is returned to the precipitation and impurity removal.

[0031] In an optional embodiment, after the second-stage hydrolysis precipitation, lithium extraction is further included: the liquid after the second-stage precipitation is mixed with a third alkaline substance to adjust the pH value of the system to 10-11 for precipitation and lithium extraction, and solid-liquid separation is performed to obtain lithium carbonate and magnesium sulfate waste liquid.

[0032] In an optional embodiment, the third alkaline substance includes at least one of sodium carbonate, potassium carbonate, ammonium carbonate and carbon dioxide.

[0033] In an optional embodiment, the magnesium sulfate waste liquid is returned to the first-stage hydrolysis precipitation to prepare a buffer solution.

[0034] In an optional embodiment, the solid-liquid separation in the pressure leaching, the precipitation and impurity removal, the first-stage hydrolysis precipitation, the second-stage hydrolysis precipitation and the lithium extraction steps are independently selected from filtration, membrane filtration, filter press, centrifugation or sedimentation.

[0035] The present disclosure has the following beneficial effects:

[0036] The present disclosure provides a full-chain integrated method for recovering nickel and cobalt from waste ternary battery powder, which utilizes calcined battery powder and uncalcined battery powder for mixed pressurized synergistic leaching, wherein the calcined battery powder has a certain reducing property, which can omit the use of H2O2 in the acid leaching process, and thus can efficiently extract nickel, cobalt, manganese and lithium valuable metal elements from the waste ternary battery powder without consuming a reducing agent, thereby improving the leaching rate and avoiding the generation of hydrogen; then, a buffer solution composed of Mg(OH)2 and MgSO4 is used to precipitate the valuable metals, and the present disclosure controls the solid content of magnesium hydroxide and Mg in the buffer solution. 2+ The concentration can be adjusted to achieve the pH of the system being mainly precipitated nickel ions and cobalt ions, while manganese ions are not precipitated or precipitated in small amounts, thereby ensuring the purity of the nickel cobalt hydroxide product. At the same time, since the present disclosure adopts a buffer solution to regulate the pH of the solution, the system can be maintained within a stable pH range without the phenomenon of local over-alkalinity. At the same time, the growth rate of the nickel cobalt hydroxide particles is slowed down, and the adverse effects of impurities being "entrained, coated, and adsorbed" are reduced, thereby greatly improving the purity of the product and obtaining a product with low water content and large particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0038] Figure 1 is a process flow chart of the full-chain integrated method for recovering nickel and cobalt from waste ternary battery powder provided by the present invention. DETAILED DESCRIPTION

[0039] The embodiments of the present disclosure will be described in detail below with reference to the examples. However, those skilled in the art will appreciate that the following examples are intended only to illustrate the present disclosure and should not be construed as limiting the scope of the present disclosure. Where specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. Where the manufacturer of the reagents or instruments is not specified, all are commercially available conventional products.

[0040] The endpoints of the ranges and any values ​​disclosed in this disclosure are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0041] Referring to FIG1 , the present disclosure provides a fully integrated method for recovering nickel and cobalt from waste ternary battery powder, which comprises the following steps:

[0042] (1) Mixing and pulping.

[0043] The battery black powder mixed with positive and negative electrode materials obtained by discharging, disassembling, crushing and sorting the waste ternary battery is placed in a tube furnace and roasted at 500-1500°C for 1-3 hours to obtain roasted battery powder, wherein the roasted battery powder has a certain reducing property. The battery black powder of the unroasted waste ternary battery is referred to as the unroasted battery powder.

[0044] The reaction equation during the calcination process is as follows: LiNi x Co y Mn (1-x-y) O2+C→Li2CO3+MnO+NiO+CoO+Co-Ni-Mn.

[0045] The calcined battery powder and the uncalcined battery powder are mixed in a mass ratio of 1:5-20, and pure water is added to mix and slurry. During the slurrying process, the solid-liquid ratio is 3-5:1 to obtain a slurry. Since the calcined battery powder alone will produce hydrogen when it reacts with acid later, it will explode under pressure and the pressurized reaction cannot be carried out. Therefore, in the present disclosure, the amount of calcined battery powder used is less than that of the uncalcined battery powder. The calcined battery powder is mixed with the uncalcined battery powder, which not only overcomes the problem of hydrogen produced by the reaction of the single calcined battery powder with acid, but also makes full use of the reducing property of the calcined battery powder, so that the high-valent nickel, cobalt and manganese metals can be converted into ionic state, which is beneficial to improve the subsequent leaching effect.

[0046] In other embodiments of the present disclosure, the mass ratio of the calcined battery powder to the uncalcined battery powder can be, for example, any one of 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:13, 1:15, 1:16, 1:18, and 1:20, or a range between any two of them. The solid-liquid ratio during the slurrying process can be, for example, any one of 3:1, 4:1, and 5:1, or a range between any two of them. After the mixed slurrying, the slurry is further subjected to ball milling activation, and the ball milling activation time is 30-90 minutes. Ball milling can activate the battery black powder, expose more of the positive electrode material, and better react with sulfuric acid in the pressure leaching section, thereby accelerating the reaction rate and improving the pressure leaching efficiency.

[0047] (2) Pressure leaching.

[0048] The activated slurry is mixed with acid and subjected to pressure leaching. The acid added is sulfuric acid, and the amount of sulfuric acid added is 80%-200% of the theoretical sulfuric acid consumption for leaching all metals in the slurry. The liquid-to-solid ratio of sulfuric acid to slurry is 2-4:1. The reaction pressure is 0.3-3.0 MPa, the reaction temperature is 150-250°C, and the leaching time is 0.5-3.0 hours. After leaching, the solid and liquid are separated to obtain a pressurized leachate and a pressurized leaching residue.

[0049] In other embodiments of the present disclosure, the amount of sulfuric acid added is 80%, 90%, 100%, 110%, 120%, 130%, 140%, 150%, 160%, 170%, 180%, 190%, 200% of the theoretical consumption of sulfuric acid for leaching all metals in the slurry, or a range value between any two of them. The liquid-solid ratio of sulfuric acid to the slurry is 2:1, 3:1, 4:1, or a range value between any two of them. The reaction pressure can be, for example, 0.3 MPa, 0.5 MPa, 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, or 3.0 MPa, or a range value between any two of them. The present disclosure has found that further increasing the reaction pressure has little effect on the leaching rate, while reducing the reaction pressure will lead to a worse leaching rate. Therefore, selecting the reaction pressure of 0.3-3.0 MPa provided in the present disclosure can obtain a good leaching rate. The reaction temperature can be, for example, any one of 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, and 250°C, or a range between any two of them, and the leaching time can be any one of 0.5h, 1h, 1.5h, 2h, 2.5h, and 3.0h, or a range between any two of them.

[0050] In the present disclosure, the slurry contains calcined battery powder with reducing properties. Therefore, the use of H2O2 can be avoided in the pressure leaching process. Without consuming reducing agents, the valuable metal elements of nickel, cobalt, manganese and lithium in the waste ternary battery powder can be efficiently extracted, and the generation of hydrogen can be avoided at the same time.

[0051] (3) Precipitation and impurity removal.

[0052] The pressurized leaching solution is mixed with an oxidant in an amount of 1-2% of the volume of the pressurized leaching solution, and a first alkaline substance is added to adjust the pH value of the solution to 4.5-6.0 to remove impurities such as iron, aluminum, and silicon. After impurities are removed, solid and liquid are separated to obtain impurity-removed slag and impurity-removed liquid.

[0053] The oxidant includes at least one of hydrogen peroxide, manganese dioxide and chlorine. The oxidant can oxidize the divalent iron ions in the pressurized leachate into trivalent iron ions, so that the pressurized leachate can be leached under a lower pH condition. The first alkaline substance includes but is not limited to at least one of limestone, sodium carbonate and calcium oxide. The present disclosure takes lime water as the first alkaline substance as an example. Limestone is slightly soluble in water, and carbonate undergoes hydrolysis reaction. At this time, the system contains OH - , at pH 4.5-6.0, OH - It can react with impurities such as iron, aluminum, and silicon in the system to form precipitates, but will not precipitate with the valuable metals to be recovered, thereby effectively removing impurities.

[0054] (4) One-stage hydrolysis and precipitation.

[0055] The impurity-removed liquid is mixed with a buffer solution consisting of Mg(OH)2 and MgSO4 and stirred for 1-3 hours to precipitate nickel ions and cobalt ions, and the solid-liquid separation is performed to obtain the product nickel-cobalt hydroxide and a precipitated liquid.

[0056] The solid content of magnesium hydroxide in the buffer solution is 1%-40%, Mg 2+ The concentration is 5-45 g / L. In other embodiments of the present disclosure, the solid content of magnesium hydroxide in the buffer solution is 1%, 3%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 20%, 25%, 29%, 31%, 35%, 36%, 38%, 40% or any range between two of them, Mg 2+The concentration can be, for example, 5 g / L, 6 g / L, 7 g / L, 8 g / L, 9 g / L, 10 g / L, 12 g / L, 15 g / L, 18 g / L, 20 g / L, 22 g / L, 24 g / L, 25 g / L, 28 g / L, 30 g / L, 32 g / L, 34 g / L, 35 g / L, 38 g / L, 40 g / L, 42 g / L, 45 g / L, or a range between any two of them. In the present disclosure, by controlling the solid content of magnesium hydroxide and Mg in the buffer solution, the magnesium hydroxide content can be increased. 2+ The concentration can be adjusted to achieve the pH of the system to mainly precipitate nickel ions and cobalt ions, while manganese ions are not precipitated or precipitated in small amounts, thereby ensuring the purity of the nickel cobalt hydroxide product. At the same time, since the present disclosure adopts a buffer solution to regulate the pH of the solution, the system can be maintained in a stable pH range without the phenomenon of local over-alkalinity. At the same time, the growth rate of the nickel cobalt hydroxide particles is slowed down, the adverse effects of impurities being "entrained, coated, and adsorbed" are reduced, the water content of the product is reduced, and the purity and particle size of the product are improved.

[0057] (5) Second stage hydrolysis and precipitation.

[0058] The first-stage precipitation liquid is mixed with a second alkaline substance. The amount of the second alkaline substance added is such that the pH value of the system is adjusted to 7.0-9.0, and a second-stage hydrolysis precipitation is performed to completely precipitate nickel ions, cobalt ions and manganese ions. The solid-liquid separation is performed to obtain the intermediate product nickel cobalt hydroxide and the second-stage precipitation liquid.

[0059] In the present disclosure, the second alkaline substance includes but is not limited to at least one of lime milk, sodium carbonate, and sodium hydroxide. The pH value of the second-stage hydrolysis precipitation is relatively high. At this time, the nickel ions, cobalt ions, and manganese ions that were not completely precipitated in the first-stage hydrolysis can be fully precipitated, ensuring that the valuable metals in the pressurized leachate are fully recovered. Since a large amount of manganese ions are precipitated during the second-stage hydrolysis precipitation, the obtained nickel cobalt hydroxide has poor purity and can only be used as an intermediate product. The intermediate nickel cobalt hydroxide can be returned to the precipitation and impurity removal step. The intermediate nickel cobalt hydroxide is alkaline. Returning it to the precipitation and impurity removal step can, on the one hand, reduce the amount of limestone added, and on the other hand, further recover the nickel, cobalt, and manganese in the intermediate nickel cobalt hydroxide.

[0060] (6) Lithium extraction.

[0061] The liquid after the second stage precipitation is mixed with a third alkaline substance to precipitate and extract lithium, and solid-liquid separation is performed to produce lithium carbonate and magnesium sulfate waste liquid. The third alkaline substance is added in an amount sufficient to adjust the system pH to 10-11. The magnesium sulfate waste liquid can be returned to the first stage hydrolysis precipitation to prepare a buffer solution. In the present disclosure, the third alkaline substance includes but is not limited to at least one of sodium carbonate, potassium carbonate, ammonium carbonate, and carbon dioxide. In the present disclosure, carbonate ions are used to precipitate the liquid after the second stage precipitation to produce lithium carbonate.

[0062] All solid-liquid separation methods involved in the present disclosure include but are not limited to filtration, membrane filtration, filter press, centrifugation or sedimentation, and can be selected according to actual conditions during actual recovery.

[0063] The features and performance of the present disclosure are further described in detail below with reference to the embodiments.

[0064] Example 1

[0065] This embodiment provides a fully integrated method for recovering nickel and cobalt from waste ternary battery powder, which comprises the following steps:

[0066] (1) The battery black powder obtained by discharging, disassembling, crushing and sorting the waste ternary batteries is placed in a tube furnace for reaction for 1 hour at a reaction temperature of 600° C. to obtain a calcined battery powder with reducing properties;

[0067] (2) The calcined battery powder and the uncalcined waste ternary battery powder are mixed uniformly in proportion to obtain a ternary battery powder mixture, and pure water is added to mix and prepare a slurry; in the ternary battery powder mixture, the calcined battery powder: uncalcined battery = 1:5, and the solid-liquid ratio is 4:1. The mixture is placed in a ball mill and mechanically activated for 60 minutes to obtain an activated slurry;

[0068] (3) adding the activated slurry and sulfuric acid into a high-pressure reactor for pressure leaching, wherein the amount of sulfuric acid added is 110% of the theoretical consumption of sulfuric acid for leaching all metals in the slurry added into the reactor, the liquid-solid ratio is 3:1, the reaction temperature is 150°C, the reaction pressure is 0.4 MPa, the leaching time is 1 hour, and after leaching, the solid and liquid are separated to obtain a pressure leaching solution and a pressure leaching residue;

[0069] (4) 30% hydrogen peroxide is added to the pressurized leaching solution and stirred continuously to convert the divalent iron ions in the solution into trivalent iron ions. The amount of hydrogen peroxide added is 1% of the volume of the pressurized leaching solution. The solution is kept at a constant temperature of 50°C, and limestone is added to adjust the pH to 5.0. Impurities such as iron, aluminum, and silicon are removed and separated by precipitation to obtain a decontaminated slag and a decontaminated liquid.

[0070] (5) The impurity-removed liquid was continuously added to the buffer solution, the temperature was maintained at 40°C, and stirred for 2.0 hours. In the buffer solution, the solid content of magnesium hydroxide was 10%, Mg 2+ The concentration is 15g / L, nickel and cobalt are precipitated, and the product nickel and cobalt hydroxide and a post-precipitation liquid are obtained by filtration;

[0071] (6) adding lime milk to the liquid after the first stage precipitation, adjusting the solution pH to 8.5, performing a second stage hydrolysis precipitation, filtering to obtain an intermediate product nickel cobalt hydroxide and the liquid after the second stage precipitation, and returning the intermediate product nickel cobalt hydroxide to the precipitation and impurity removal step;

[0072] (7) Sodium carbonate is added to the liquid after the second stage precipitation, and the pH of the solution is adjusted to 10. Lithium is extracted by precipitation, and lithium carbonate and magnesium sulfate waste liquid are obtained by filtration. The magnesium sulfate waste liquid can be returned to the first stage precipitation to prepare a buffer solution.

[0073] Pass ICP element test:

[0074] Battery black powder: Ni content 21.77%, Co content 3.29%, Mn content 4.27%, Fe content 0.21%, Al content 0.21%, Cu content 0.24%;

[0075] Pressure leaching residue: Ni content 1.27%, Co content 0.58%, Mn content 0.88%, Fe content 0.08%, Al content 0.07%, Cu content 0.08%;

[0076] Pressure leachate: Ni concentration 18.31 g / L, Co concentration 2.78 g / L, Mn concentration 4.52 g / L, Fe concentration 0.15 g / L, Al concentration 0.07 g / L, Cu concentration 0.006 g / L;

[0077] Product nickel cobalt hydroxide: Ni content 40.21%, Co content 4.86%, Mn content 6.17%, Fe content 0.01%, Al content 0.01%, Cu content 0.002%, Mg content 1.47%;

[0078] Liquid after the first stage of precipitation: Ni concentration 0.42g / L, Co concentration 0.026g / L, Mn concentration 2.86g / L, Fe concentration 0.003g / L, Al concentration 0.002g / L, Cu concentration 0.001g / L.

[0079] Example 2

[0080] This embodiment provides a fully integrated method for recovering nickel and cobalt from waste ternary battery powder, which comprises the following steps:

[0081] (1) The battery black powder obtained by discharging, disassembling, crushing and sorting the waste ternary batteries is placed in a tube furnace for reaction for 2 hours at a reaction temperature of 700°C to obtain a calcined battery powder with reducing properties;

[0082] (2) The calcined battery powder and the uncalcined waste ternary battery powder are mixed uniformly in proportion to obtain a ternary battery powder mixture, and pure water is added to mix and prepare a slurry; in the ternary battery powder mixture, the calcined battery powder: uncalcined battery = 1:10, the solid-liquid ratio is 4:1, and the mixture is placed in a ball mill and mechanically activated for 60 minutes to obtain an activated slurry;

[0083] (3) adding the activated slurry and sulfuric acid into a high-pressure reactor for pressure leaching, wherein the amount of sulfuric acid added is 150% of the theoretical consumption of sulfuric acid for leaching all metals in the slurry added into the reactor, the liquid-solid ratio is 3:1, the reaction temperature is 210°C, the reaction pressure is 2.3 MPa, the leaching time is 2 h, and after leaching, the solid and liquid are separated to obtain a pressure leaching solution and a pressure leaching residue;

[0084] (4) 30% hydrogen peroxide is added to the pressurized leaching solution and stirred continuously to convert the divalent iron ions in the solution into trivalent iron ions. The amount of hydrogen peroxide added is 1% of the volume of the leaching solution. The solution is kept at a constant temperature of 50°C, and limestone is added to adjust the pH to 5.0. Impurities such as iron, aluminum, and silicon are removed and separated by precipitation to obtain a decontaminated slag and a decontaminated liquid.

[0085] (5) The impurity-removed liquid was continuously added to the buffer solution, the temperature was maintained at 40°C, and stirred for 1.0h. In the buffer solution, the solid content of magnesium hydroxide was 20%, Mg 2+ The concentration is 30g / L, nickel and cobalt are precipitated, and the product nickel and cobalt hydroxide and a post-precipitation liquid are obtained by filtration;

[0086] (6) adding lime milk to the liquid after the first stage precipitation, adjusting the solution pH to 8.5, performing a second stage hydrolysis precipitation, filtering to obtain an intermediate product nickel cobalt hydroxide and the liquid after the second stage precipitation, and returning the intermediate product nickel cobalt hydroxide to the precipitation and impurity removal step;

[0087] (7) Sodium carbonate is added to the liquid after the second stage precipitation, and the pH of the solution is adjusted to 10.5. Lithium is extracted by precipitation, and lithium carbonate and magnesium sulfate waste liquid are obtained by filtration. The magnesium sulfate waste liquid can be returned to the first stage precipitation to prepare the buffer solution.

[0088] Pass ICP element test:

[0089] Battery black powder: Ni content 21.77%, Co content 3.29%, Mn content 4.27%, Fe content 0.21%, Al content 0.21%, Cu content 0.24%;

[0090] Pressure leaching residue: Ni content 0.11%, Co content 0.01%, Mn content 0.04%, Fe content 0.18%, Al content 0.01%, Cu content 0.0001%;

[0091] Pressure leachate: Ni concentration 22.38 g / L, Co concentration 3.41 g / L, Mn concentration 5.14 g / L, Fe concentration 0.18 g / L, Al concentration 0.09 g / L, Cu concentration 0.01 g / L;

[0092] Product nickel cobalt hydroxide: Ni content 46.52%, Co content 6.75%, Mn content 7.52%, Fe content 0.01%, Al content 0.009%, Cu content 0.003%, Mg content 1.50%;

[0093] Liquid after the first stage of precipitation: Ni concentration 0.07g / L, Co concentration 0.0001g / L, Mn concentration 2.54g / L, Fe concentration 0.002g / L, Al concentration 0.001g / L, Cu concentration 0.001g / L.

[0094] Example 3

[0095] This embodiment provides a fully integrated method for recovering nickel and cobalt from waste ternary battery powder, which comprises the following steps:

[0096] (1) The battery black powder obtained by discharging, disassembling, crushing and sorting the waste ternary batteries is placed in a tube furnace for reaction for 1 hour at a reaction temperature of 1500° C. to obtain a calcined battery powder with reducing properties;

[0097] (2) The calcined battery powder and the uncalcined waste ternary battery powder are mixed uniformly in proportion to obtain a ternary battery powder mixture, and pure water is added to mix and prepare a slurry; in the ternary battery powder mixture, the calcined battery powder: uncalcined battery = 1:20, the solid-liquid ratio is 5:1, and the mixture is placed in a ball mill and mechanically activated for 90 minutes to obtain an activated slurry;

[0098] (3) adding the activated slurry and sulfuric acid into a high-pressure reactor for pressure leaching, wherein the amount of sulfuric acid added is 200% of the theoretical consumption of sulfuric acid for leaching all metals in the slurry added into the reactor, the liquid-solid ratio is 2:1, the reaction temperature is 250°C, the reaction pressure is 3 MPa, the leaching time is 0.5 h, and after leaching, the solid and liquid are separated to obtain a pressure leaching solution and a pressure leaching residue;

[0099] (4) 30% hydrogen peroxide is added to the pressurized leaching solution and stirred continuously to convert the divalent iron ions in the solution into trivalent iron ions. The amount of hydrogen peroxide added is 1% of the volume of the pressurized leaching solution. The solution is kept at a constant temperature of 50°C, and limestone is added to adjust the pH to 4.5. Impurities such as iron, aluminum, and silicon are removed and separated by precipitation to obtain a decontaminated slag and a decontaminated liquid.

[0100] (5) The impurity-removed liquid was continuously added to the buffer solution, the temperature was maintained at 40°C, and stirred for 1.0h. In the buffer solution, the solid content of magnesium hydroxide was 40%, Mg 2+ The concentration is 45g / L, nickel and cobalt are precipitated, and the product nickel and cobalt hydroxide and a post-precipitation liquid are obtained by filtration;

[0101] (6) adding lime milk to the liquid after the first stage precipitation, adjusting the solution pH to 8.5, performing a second stage hydrolysis precipitation, filtering to obtain an intermediate product nickel cobalt hydroxide and the liquid after the second stage precipitation, and returning the intermediate product nickel cobalt hydroxide to the precipitation and impurity removal step;

[0102] (7) Sodium carbonate is added to the liquid after the second stage precipitation, and the pH of the solution is adjusted to 10.5. Lithium is extracted by precipitation, and lithium carbonate and magnesium sulfate waste liquid are obtained by filtration. The magnesium sulfate waste liquid can be returned to the first stage precipitation to prepare the buffer solution.

[0103] Pass ICP element test:

[0104] Battery black powder: Ni content 21.77%, Co content 3.29%, Mn content 4.27%, Fe content 0.21%, Al content 0.21%, Cu content 0.24%;

[0105] Pressure leaching residue: Ni content 0.05%, Co content 0.001%, Mn content 0.02%, Fe content 0.07%, Al content 0.03%, Cu content 0.0001%;

[0106] Pressure leachate: Ni concentration 23.38 g / L, Co concentration 3.51 g / L, Mn concentration 5.34 g / L, Fe concentration 0.23 g / L, Al concentration 0.12 g / L, Cu concentration 0.05 g / L;

[0107] Product nickel cobalt hydroxide: Ni content 43.52%, Co content 6.25%, Mn content 7.82%, Fe content 0.001%, Al content 0.005%, Cu content 0.002%, Mg content 1.53%;

[0108] Liquid after the first stage of precipitation: Ni concentration 0.003g / L, Co concentration 0.0001g / L, Mn concentration 1.44g / L, Fe concentration 0.002g / L, Al concentration 0.0001g / L, Cu concentration 0.0001g / L.

[0109] Comparative Example 1

[0110] This comparative example discloses a method for recovering nickel and cobalt from ternary battery powder, which adopts the method of H2SO4 atmospheric pressure leaching-NaOH / Na2CO3 precipitation of nickel, cobalt and manganese, and specifically comprises the following steps:

[0111] (1) The battery black powder mixed with positive and negative electrode materials obtained by discharging, disassembling, crushing and sorting the waste ternary batteries was mixed with pure water to prepare a slurry with a solid-liquid ratio of 4:1, placed in a ball mill, and mechanically activated for 60 minutes to obtain an activated slurry;

[0112] (2) adding the activated slurry and sulfuric acid into a beaker for leaching, wherein the amount of sulfuric acid added is 150% of the theoretical consumption of sulfuric acid for leaching all metals in the slurry added into the reactor, the liquid-solid ratio is 3:1, the reaction temperature is 80°C, the reaction pressure is 0.1 MPa, the leaching time is 2 h, and after leaching, the solid and liquid are separated to obtain atmospheric pressure leachate and atmospheric pressure leaching residue;

[0113] (3) 30% hydrogen peroxide is added to the pressurized leaching solution and stirred continuously to convert the divalent iron ions in the solution into trivalent iron ions. The amount of hydrogen peroxide added is 1% of the volume of the pressurized leaching solution. The solution is kept at a constant temperature of 50°C, and limestone is added to adjust the pH to 5.0. Impurities such as iron, aluminum, and silicon are removed and separated by precipitation to obtain a decontaminated slag and a decontaminated liquid.

[0114] (4) continuously adding NaOH or Na2CO3 solution to the impurity-removed liquid, maintaining the temperature at 40°C, stirring for 2.0 hours, adjusting the pH to 8.0, precipitating nickel and cobalt, and filtering to obtain the product nickel cobalt hydroxide and a first precipitated liquid;

[0115] (5) adding lime milk to the liquid after the first stage precipitation, adjusting the pH of the solution to 8.5, performing a second stage hydrolysis precipitation, and filtering to obtain the intermediate product nickel cobalt hydroxide and the liquid after the second stage precipitation;

[0116] (6) Sodium carbonate is added to the liquid after the second stage precipitation, and the pH of the solution is adjusted to 10.5. Lithium is extracted by precipitation, and lithium carbonate and magnesium sulfate waste liquid are obtained by filtration.

[0117] Pass ICP element test:

[0118] Battery black powder: Ni content 21.77%, Co content 3.29%, Mn content 4.27%, Fe content 0.21%, Al content 0.21%, Cu content 0.24%;

[0119] Atmospheric pressure leaching residue: Ni content 17.32%, Co content 2.52%, Mn content 3.34%, Fe content 0.13%, Al content 0.11%, Cu content 0.11%;

[0120] Atmospheric pressure leachate: Ni concentration 4.28 g / L, Co concentration 0.47 g / L, Mn concentration 1.10 g / L, Fe concentration 0.124 g / L, Al concentration 0.05 g / L, Cu concentration 0.01 g / L;

[0121] Product nickel cobalt hydroxide: Ni content 36.54%, Co content 3.45%, Mn content 5.36%, Fe content 0.06%, Al content 0.01%, Cu content 0.02%, Mg content 1.1%;

[0122] Liquid after the first stage of precipitation: Ni concentration 0.07g / L, Co concentration 0.0001g / L, Mn concentration 0.84g / L, Fe concentration 0.002g / L, Al concentration 0.001g / L, Cu concentration 0.001g / L.

[0123] This comparative example is a method of H2SO4 atmospheric pressure leaching-NaOH / Na2CO3 precipitation of nickel, cobalt and manganese, which does not include the synergistic pressure leaching of calcined-uncalcined battery powder and buffer solution as a precipitant in the present disclosure. The leaching efficiency is low and the leaching rate is low. The prepared nickel cobalt hydroxide product has a low Ni+Co+Mn metal content. Due to the strong alkalinity, the product grains grow too fast, resulting in excessively fine grains, and a large number of coated water molecules and impurities. The leaching efficiency and leaching rate of this process are low. The produced nickel cobalt hydroxide has a finer particle size, a higher water content and a lower nickel and cobalt content than that in the embodiment.

[0124] Comparative Example 2

[0125] This comparative example is basically the same as Example 1, except that this comparative example only uses unfired battery powder for activation, wherein, step (1): discharging, disassembling, crushing, and sorting waste ternary batteries to obtain battery black powder; step (2): adding pure water to the unfired waste ternary battery powder for mixing and slurrying; the solid-liquid ratio is 4:1, and the mixture is placed in a ball mill and mechanically activated for 60 minutes to obtain an activated slurry.

[0126] Pass ICP element test:

[0127] Pressure leaching residue: Ni content 15.27%, Co content 2.48%, Mn content 2.57%, Fe content 0.08%, Al content 0.07%, Cu content 0.08%;

[0128] Pressure leachate: Ni concentration 4.88 g / L, Co concentration 0.53 g / L, Mn concentration 1.26 g / L, Fe concentration 0.15 g / L, Al concentration 0.07 g / L, Cu concentration 0.006 g / L;

[0129] From the data of Example 1 and Comparative Example 2, it can be seen that without adding the reducing calcined battery powder, the leaching effect is extremely poor, wherein the high-valent nickel, cobalt and manganese metals cannot be converted into ionic state and cannot be recycled.

[0130] Comparative Example 3

[0131] This comparative example is basically the same as Example 1, except that activation is not performed in this comparative example, wherein, step (2): the calcined battery powder and the uncalcined waste ternary battery powder are mixed uniformly in proportion to obtain a ternary battery powder mixture, and pure water is added to mix and slurry; in the ternary battery powder mixture, the calcined battery powder: uncalcined battery = 1:5, and the solid-liquid ratio is 4:1.

[0132] Pass ICP element test:

[0133] Pressure leaching residue: Ni content 2.27%, Co content 0.65%, Mn content 1.02%, Fe content 0.11%, Al content 0.11%, Cu content 0.12%;

[0134] Pressurized leaching solution: Ni concentration 16.51 g / L, Co concentration 2.48 g / L, Mn concentration 4.02 g / L, Fe concentration 0.11 g / L, Al concentration 0.05 g / L, Cu concentration 0.005 g / L.

[0135] From the data of Example 1 and Comparative Example 3, it can be seen that without activation of the battery powder, the leaching effect is slightly worse than that after activation, and the reaction time is longer.

[0136] Comparative Example 4

[0137] This comparative example is substantially the same as Example 1, except that atmospheric pressure leaching is employed in this comparative example. Step (3): adding the activated slurry and sulfuric acid to a reactor for atmospheric pressure leaching, wherein the amount of sulfuric acid added is 110% of the theoretical sulfuric acid consumption for leaching all metals in the slurry added to the reactor, the liquid-to-solid ratio is 3:1, the reaction temperature is 80° C., the reaction pressure is 0.1 MPa, the leaching time is 1 hour, and after leaching, solid-liquid separation is performed to obtain a leachate and a leaching residue.

[0138] Pass ICP element test:

[0139] Atmospheric pressure leaching residue: Ni content 3.17%, Co content 0.88%, Mn content 1.12%, Fe content 0.15%, Al content 0.12%, Cu content 0.14%;

[0140] Atmospheric pressure leachate: Ni concentration 14.35 g / L, Co concentration 1.96 g / L, Mn concentration 3.82 g / L, Fe concentration 0.10 g / L, Al concentration 0.04 g / L, Cu concentration 0.004 g / L.

[0141] It can be seen from the data of Example 1 and Comparative Example 4 that when leaching battery powder at normal pressure is carried out, the leaching rate decreases within the same leaching time, resulting in a longer reaction time and a decreased leaching effect.

[0142] Comparative Example 5

[0143] This comparative example is basically the same as Example 1, except that the solid content of magnesium hydroxide in the buffer solution is 60%, Mg 2+ The concentration is 60g / L.

[0144] Pass ICP element test:

[0145] Product nickel cobalt hydroxide: Ni content 30.54%, Co content 1.86%, Mn content 3.36%, Fe content 0.06%, Al content 0.02%, Cu content 0.02%, Mg content 10.21%;

[0146] It can be seen from the data of Example 1 and Comparative Example 5 that when the solid content of magnesium hydroxide in the buffer solution exceeds a certain range, the nickel and cobalt contents in the product nickel cobalt hydroxide decrease and the impurities increase.

[0147] Comparative Example 6

[0148] This comparative example is basically the same as Example 1, except that the buffer solution in this comparative example is NH4Cl and NH3·H2O, wherein the amount of NH4Cl is 50g, the amount of NH3·H2O is 3.5mL, and 500mL of buffer solution is prepared.

[0149] Pass ICP element test:

[0150] Product nickel cobalt hydroxide: Ni content 38.21%, Co content 4.36%, Mn content 5.67%, Fe content 0.02%, Al content 0.02%, Cu content 0.003%, Mg content 1.3%;

[0151] Liquid after the first stage of precipitation: Ni concentration 0.46g / L, Co concentration 0.056g / L, Mn concentration 2.97g / L, Fe concentration 0.004g / L, Al concentration 0.002g / L, Cu concentration 0.001g / L, Cl concentration 30g / L.

[0152] From the data of Example 1 and Comparative Example 6, it can be seen that the precipitation effect in Comparative Example 6 is slightly worse than that in Example 1, wherein the proportion of valuable metals in the product nickel cobalt hydroxide is slightly lower, and the liquid after one stage of precipitation contains a large amount of impurity chloride ions, requiring unnecessary wastewater treatment, which greatly increases the cost.

[0153] In summary, the present disclosure provides a full-chain integrated method for recovering nickel and cobalt from waste ternary battery powder, which utilizes calcined battery powder and uncalcined battery powder for mixed pressurized synergistic leaching, wherein the calcined battery powder has a certain reducing property, which can omit the use of H2O2 in the acid leaching process, and thus can efficiently extract nickel, cobalt, manganese and lithium valuable metal elements from waste ternary battery powder without consuming reducing agents, thereby improving the leaching rate and avoiding the generation of hydrogen; then, a buffer solution composed of Mg(OH)2 and MgSO4 is used to precipitate the valuable metals, and the present disclosure controls the solid content of magnesium hydroxide and Mg in the buffer solution. 2+The concentration can be adjusted to achieve the pH of the system being mainly precipitated nickel ions and cobalt ions, while manganese ions are not precipitated or precipitated in small amounts, thereby ensuring the purity of the nickel cobalt hydroxide product. At the same time, since the present disclosure adopts a buffer solution to regulate the pH of the solution, the system can be maintained within a stable pH range without the phenomenon of local over-alkalinity. At the same time, the growth rate of the nickel cobalt hydroxide particles is slowed down, and the adverse effects of impurities being "entrained, coated, and adsorbed" are reduced, thereby greatly improving the purity of the product and obtaining a product with low water content and large particles.

[0154] The above describes in detail the optional embodiments of the present disclosure, but the present disclosure is not limited thereto. Within the technical concept of the present disclosure, various simple variations of the technical solution of the present disclosure can be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as the contents disclosed by the present disclosure and fall within the scope of protection of the present disclosure. Industrial Applicability

[0155] The present disclosure provides a full-chain integrated method for recovering nickel and cobalt from waste ternary battery powder, which utilizes calcined battery powder and uncalcined battery powder for mixed pressurized synergistic leaching, wherein the calcined battery powder has a certain reducing property, which can omit the use of H2O2 in the acid leaching process, and thus can efficiently extract nickel, cobalt, manganese and lithium valuable metal elements from the waste ternary battery powder without consuming a reducing agent, thereby improving the leaching rate and avoiding the generation of hydrogen; then, a buffer solution composed of Mg(OH)2 and MgSO4 is used to precipitate the valuable metals, and the present disclosure controls the solid content of magnesium hydroxide and Mg in the buffer solution. 2+ The concentration can be adjusted to achieve the pH of the system being mainly precipitated nickel ions and cobalt ions, while manganese ions are not precipitated or precipitated in small amounts, thereby ensuring the purity of the nickel cobalt hydroxide product. At the same time, since the present disclosure adopts a buffer solution to regulate the pH of the solution, the system can be maintained within a stable pH range without the phenomenon of local over-alkalinity. At the same time, the growth rate of the nickel cobalt hydroxide particles is slowed down, and the adverse effects of impurities being "entrained, coated, and adsorbed" are reduced, thereby greatly improving the purity of the product and obtaining a product with low water content and large particles.

Claims

1. A method for recovering nickel and cobalt from waste ternary battery powder with a full chain integration, characterized in that: It includes: Mixed Pulping: Mixing the calcined battery powder and the uncalcined battery powder to obtain slurry; Pressure leaching: mixing the slurry with acid and leaching under pressure, separating the solid and liquid after leaching to obtain pressure leaching liquid and pressure leaching residue; Precipitation and impurity removal: after mixing the pressurized leaching solution with an oxidant, adjusting the solution pH to 4.5-6.0 to remove impurities such as iron, aluminum and silicon, and separating the solid and liquid after impurity removal to obtain impurity-removed slag and impurity-removed liquid; One-stage hydrolysis precipitation: the impurity-removed liquid is mixed and stirred with a buffer solution composed of Mg(OH)2 and MgSO4 to precipitate nickel ions and cobalt ions, wherein the solid content of magnesium hydroxide in the buffer solution is 1%-40%, and the solid content of Mg(OH)2 and MgSO4 is 1%-40%. 2+ The concentration is 5-45g / L, and the solid-liquid separation obtains the product nickel cobalt hydroxide and a post-precipitation liquid.

2. The method for recovering nickel and cobalt from waste ternary battery powder in a full-chain integrated manner according to claim 1, characterized in that: The mass ratio of the calcined battery powder to the uncalcined battery powder is 1:5-20.

3. The method for recovering nickel and cobalt from waste ternary battery powder according to any one of claims 1 to 2, characterized in that: The solid-liquid ratio during the pulping process is 3-5:

1.

4. The method for recovering nickel and cobalt from waste ternary battery powder according to any one of claims 1 to 3, characterized in that: The solvent used in the pulping is water.

5. The method for recovering nickel and cobalt from waste ternary battery powder according to any one of claims 1 to 4, characterized in that: The calcined battery powder is obtained by placing battery black powder of waste ternary batteries in a tubular furnace and calcining at 500-1500° C. for 1-3 hours.

6. The method for recovering nickel and cobalt from waste ternary battery powder according to any one of claims 1 to 5, characterized in that: The mixing and slurrying process further comprises ball milling and activating the slurry.

7. The method for recovering nickel and cobalt from waste ternary battery powder according to claim 6, characterized in that: The ball milling activation time is 30-90 minutes.

8. The method for recovering nickel and cobalt from waste ternary battery powder according to any one of claims 1 to 7, characterized in that: In the step of pressurized leaching, the reaction pressure is 0.3-3.0 MPa.

9. The method for recovering nickel and cobalt from waste ternary battery powder according to any one of claims 1 to 8, characterized in that: In the step of pressure leaching, the reaction temperature is 150-250°C.

10. The method for recovering nickel and cobalt from waste ternary battery powder according to any one of claims 1 to 9, characterized in that: In the step of pressurized leaching, the leaching time is 0.5-3.0h.

11. The method for recovering nickel and cobalt from waste ternary battery powder according to any one of claims 1 to 10, characterized in that: In the pressure leaching step, the acid added is sulfuric acid, the amount of sulfuric acid added is 80%-200% of the theoretical sulfuric acid consumption for leaching all metals in the slurry, and the liquid-to-solid ratio of the sulfuric acid to the slurry is 2-4:

1.

12. The method for recovering nickel and cobalt from waste ternary battery powder according to any one of claims 1 to 11, characterized in that: The oxidant includes at least one of hydrogen peroxide, manganese dioxide and chlorine.

13. The method for recovering nickel and cobalt from waste ternary battery powder according to any one of claims 1 to 12, characterized in that: The amount of the oxidant added is 1-2% of the volume of the pressure leaching solution.

14. The method for recovering nickel and cobalt from waste ternary battery powder according to any one of claims 1 to 13, characterized in that: In the step of precipitation and impurity removal, a first alkaline substance is used to adjust the pH value of the solution, and the first alkaline substance includes at least one of limestone, sodium carbonate and calcium oxide.

15. The method for recovering nickel and cobalt from waste ternary battery powder according to any one of claims 1 to 14, characterized in that: The mixing and stirring time in the hydrolysis and precipitation step is 1-3 hours.

16. The method for recovering nickel and cobalt from waste ternary battery powder according to any one of claims 1 to 15, characterized in that: After the first stage hydrolysis precipitation, the method further comprises a second stage hydrolysis precipitation: the first stage precipitation liquid is mixed with a second alkaline substance to adjust the pH value of the system to 7.0-9.0 to perform a second stage hydrolysis precipitation to completely precipitate nickel ions, cobalt ions and manganese ions, and solid-liquid separation is performed to obtain an intermediate product of nickel cobalt hydroxide and the second stage precipitation liquid.

17. The method for recovering nickel and cobalt from waste ternary battery powder according to claim 16, characterized in that: The second alkaline substance includes at least one of lime milk, sodium carbonate and sodium hydroxide.

18. The method for recovering nickel and cobalt from waste ternary battery powder according to any one of claims 16 to 17, characterized in that: The intermediate product nickel-cobalt hydroxide is returned to the precipitation and impurity removal.

19. The method for recovering nickel and cobalt from waste ternary battery powder according to any one of claims 16 to 18, characterized in that: After the second-stage hydrolysis precipitation, the method further includes lithium extraction: mixing the second-stage precipitation liquid with a third alkaline substance to adjust the pH value of the system to 10-11 to perform precipitation and lithium extraction, and solid-liquid separation to obtain lithium carbonate and magnesium sulfate waste liquid.

20. The method for recovering nickel and cobalt from waste ternary battery powder according to claim 19, characterized in that: The third alkaline substance includes at least one of sodium carbonate, potassium carbonate, ammonium carbonate and carbon dioxide.

21. The method for recovering nickel and cobalt from waste ternary battery powder according to any one of claims 19 to 20, characterized in that: The magnesium sulfate waste liquid can be returned to the first-stage hydrolysis precipitation to prepare a buffer solution.

22. The method for recovering nickel and cobalt from waste ternary battery powder according to any one of claims 19 to 21, characterized in that: The solid-liquid separation in the steps of pressure leaching, precipitation and impurity removal, the first-stage hydrolysis precipitation, the second-stage hydrolysis precipitation and lithium extraction are independently selected from filtration, membrane filtration, filter pressing, centrifugation or sedimentation.

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