Method for selectively separating and recycling valuable metal from ternary battery positive electrode powder

Abstract

The invention discloses a method for selectively separating and recovering valuable metals from ternary battery positive electrode powder, which comprises the following steps: (1) leaching the ternary battery positive electrode powder to obtain a leaching solution; (2) the pH value of the leachate is controlled to be 2.0-4.0, meanwhile, an oxidation-reduction potential regulator is added into the leachate, the oxidation-reduction potential Eh of the leachate is controlled to be 200-350 mV, under the conditions, a vulcanizing agent is slowly added, CoS, NiS and CuS precipitates are generated through a reaction, and Mn < 2 + > is reserved in the solution; and after the reaction is finished, carrying out solid-liquid separation to obtain sulfide slag rich in cobalt, nickel and copper and purified liquid containing manganese and lithium. According to the method for selectively separating and recycling the valuable metal from the ternary battery positive electrode powder, cobalt, nickel and copper can be selectively vulcanized and precipitated by accurately controlling the pH value and the oxidation-reduction potential Eh.

Description

Technical Field

[0001] This invention belongs to the field of battery material recycling, and in particular relates to a method for recycling cathode materials. Background Technology

[0002] With the rapid development of the new energy vehicle industry, a large number of ternary lithium-ion batteries are entering their retirement period. The cathode materials of ternary batteries contain abundant valuable metals such as nickel, cobalt, manganese, and lithium, possessing extremely high recycling value. Hydrometallurgy is the mainstream technology for recycling these metals, typically including steps such as crushing and sorting, acid leaching, impurity removal, and elemental separation.

[0003] In the separation process of leachate (mainly containing Ni, Co, Mn, and Li), efficiently separating manganese from cobalt and nickel is a technical challenge. Manganese has similar chemical properties to cobalt and nickel, making separation difficult. Traditional methods often employ solvent extraction, but this method is lengthy, consumes large amounts of reagents, and generates significant amounts of organic wastewater. Another common method is sulfide precipitation, which involves adding Na₂S or introducing H₂S gas to precipitate Co, Ni, Cu, etc., as sulfides. However, this method has significant drawbacks: 1. Vulcanizing agents readily react with Mn 2+ The reaction produces MnS precipitate, resulting in a significant loss of manganese and reducing the manganese recovery rate and product value.

[0004] 2. Using sulfiding agents under acidic conditions can easily produce highly toxic and explosive H2S gas, posing a serious threat to safe production and environmental protection.

[0005] 3. The sedimentation process is difficult to control and easily generates colloidal or fine particulate sediments, making filtration difficult.

[0006] Therefore, developing a new process that can efficiently, cleanly, and selectively separate manganese and cobalt-nickel and achieve high-value recovery of each component has become an urgent need in this field. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide a method for selectively separating and recovering valuable metals from ternary battery cathode powder with a short process flow, high separation efficiency, environmental friendliness, and the ability to simultaneously enrich cobalt, nickel and copper.

[0008] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows: A method for selectively separating and recovering valuable metals from ternary lithium battery cathode powder includes the following steps: (1) Leaching the positive electrode powder of a ternary battery to obtain a sample containing Mn 2+ Co 2+ Ni 2+ Cu 2+Li + The leachate; (2) Control the pH of the leachate to 2.0-4.0, and simultaneously add a redox potential regulator to the leachate to control the redox potential Eh of the leachate to 200-350mV. Under the above conditions, slowly add the sulfiding agent to react and generate CoS, NiS and CuS precipitates, while Mn... 2+ The solution is retained; after the reaction is completed, the solid and liquid are separated to obtain a sulfide slag rich in cobalt, nickel, and copper, and a purified liquid containing manganese and lithium.

[0009] In the above method, preferably, step (2) includes two stages, as follows: First stage: Control the pH of the reaction system to 3.5-4.0, the redox potential Eh to 300-350mV, and slowly add the initial vulcanizing agent, which accounts for 10-30% of the total molar amount of the vulcanizing agent, and react for 5-30 minutes; Second stage: Control the pH of the reaction system to 2.5-3.0 and the redox potential Eh to 200-280mV, and slowly add the remaining sulfiding agent to complete the sulfidation precipitation reaction.

[0010] In the above method, preferably, in the second stage, a selective regulator is added to the reaction system, wherein the selective regulator is at least one of a surfactant or a polymeric flocculant; the amount of the selective regulator added is 0.01-0.1% of the mass of the leachate.

[0011] In the above method, preferably, the surfactant is at least one of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate; and the polymeric flocculant is at least one of polyacrylamide and sodium polyacrylate.

[0012] In the above method, preferably, there is a aging time of 10-30 minutes between the first stage and the second stage.

[0013] In the above method, preferably, the redox potential regulator is one or more of hydrogen peroxide, air, or ozone.

[0014] In the above methods, preferably, an online pH meter and a redox potential meter are used to monitor and control the reaction process in real time to ensure the pH value and redox potential Eh of the reaction system.

[0015] In the above method, preferably, the sulfiding agent is sodium thiosulfate or sodium sulfide, and the total amount of the sulfiding agent added is 1.0-1.2 times the theoretical stoichiometry for complete precipitation of Co, Ni, and Cu.

[0016] In the above method, preferably, sulfuric acid and a reducing agent are used for leaching the positive electrode powder of the ternary battery, wherein the reducing agent is hydrogen peroxide or sodium sulfite.

[0017] In the above method, preferably, the purified liquid containing manganese and lithium is subjected to deep purification to remove trace impurities and manganese and lithium are recovered respectively; the deep purification is to extract residual calcium and magnesium ions using P204 extractant.

[0018] In the above method, preferably, the leachate may also contain Fe. 3+ Al 3+ Iron and aluminum can be removed from the leachate using conventional methods.

[0019] The present invention provides a method for selectively separating and recovering valuable metals from ternary lithium battery cathode powder. This method achieves the separation of manganese from cobalt, nickel, and copper by precisely controlling the pH value and redox potential Eh through selective sulfidation precipitation of cobalt, nickel, and copper. However, during the selective precipitation of cobalt, nickel, and copper, the rapid nucleation process during sulfidation precipitation easily forms Mn molecules with large specific surface areas, making them highly adsorbable and prone to entrainment. 2+ The colloidal precipitation results in low manganese recovery rates. To address this issue, this invention provides a method for selectively separating and recovering valuable metals from ternary battery cathode powder based on segmented potential-controlled sulfidation precipitation. This method improves the traditional single-condition sulfidation precipitation into a multi-stage, precisely controlled process, and through the synergistic effect of selective regulators, fundamentally improves the physical morphology and separation performance of the precipitate.

[0020] Specifically: The first stage is the induction of nucleation and seed crystal preparation stage. The pH of the reaction system is controlled at 3.5-4.0, and the redox potential Eh at 300-350 mV. An initial sulfurizing agent, accounting for 10-30% of the total molar amount, is slowly added to gently induce the precipitation of CoS, NiS, and CuS, preferentially forming a small number of uniformly sized and structurally stable crystal nuclei (seed crystals), providing an ideal substrate for subsequent precipitate growth. The second stage is the controlled growth and flocculation stage. The pH of the reaction system is controlled at 2.5-3.0, and the redox potential Eh at 200-280 mV. The remaining sulfurizing agent is slowly added, along with a trace amount of selective regulator. Using the existing seed crystals, the Co in the solution is promoted to precipitate. 2+ Ni 2+ Cu 2+Ions continue to deposit and grow on the seed crystal surface instead of re-nucleating. The addition of selective regulators further inhibits colloid formation and promotes the flocculation of small particles into large, dense, easily settled, and filterable sulfide flocs. The 10-30 minute aging time between the first and second stages also facilitates manganese separation. After the reaction, solid-liquid separation is performed. The resulting sulfide slag has high Co, Ni, and Cu content, while the Mn content is significantly reduced (below 2%), which is beneficial for subsequent metallurgical processes. The purified liquid is rich in Mn and Li and has high purity.

[0021] Compared with the prior art, the advantages of the present invention are as follows: The method for selectively separating and recovering valuable metals from ternary battery cathode powder of the present invention, by precisely controlling the pH value and redox potential Eh, selectively sulfides and precipitates cobalt, nickel, and copper, and efficiently recovers lithium manganese, has the following advantages: High selectivity: By precisely controlling the pH value in the specific window of 2.0-4.0 and Eh in the range of 200-350mV, the formation of MnS is thermodynamically suppressed, while the precipitation of CoS, NiS and CuS is promoted, thus achieving efficient separation of manganese from cobalt, nickel and copper. The loss rate of manganese can be controlled to below 2%.

[0022] Safe and environmentally friendly: Within a controlled pH range, the generation of highly toxic H2S gas is effectively avoided. The use of relatively safe solid sulfurizing agents such as sodium thiosulfate makes it easier to operate and store than using H2S gas directly.

[0023] High product value: The separated cobalt-nickel-copper sulfide slag is of high grade and is a high-quality hydrometallurgical raw material, which greatly improves the economics of the recycling process.

[0024] Controllable process: The use of online monitoring and slow feeding makes the reaction process stable and controllable, and the product morphology and particle size are more uniform, which facilitates subsequent solid-liquid separation. Detailed Implementation

[0025] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0026] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0027] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0028] Example 1: A method for selectively separating and recovering valuable metals from ternary lithium battery cathode powder includes the following steps: (1) Take 1 kg of ternary battery black powder (NCM523) obtained by crushing and sorting, leach it with 2M sulfuric acid and an appropriate amount of hydrogen peroxide at 80°C for 2 hours, and obtain leachate after solid-liquid separation. Add hydrogen peroxide to leachate and adjust the pH value to 4.5 with NaOH solution to precipitate and remove iron and aluminum, and obtain pretreated liquid.

[0029] (2) Transfer the pretreated solution to a reactor equipped with a stirrer, an online pH meter, and an ORP meter. Adjust the pH of the solution to 3.0 with dilute sulfuric acid. Stabilize the ORP value of the system at 300 mV by adding a small amount of hydrogen peroxide.

[0030] (3) Under vigorous stirring, slowly add a 1 mol / L sodium thiosulfate (Na2S2O3) solution. During the addition, maintain the pH at 3.0±0.1 and the ORP at 300±10mV by automatically adding acid / base and redox potential adjuster. Stop adding sodium thiosulfate when the amount added reaches 1.1 times the theoretical amount of Co, Ni, and Cu to be precipitated. Continue stirring and aging for 30 minutes.

[0031] (4) After the reaction was completed, the mixture was filtered to obtain black sulfide slag and light pink filtrate. The final manganese loss rate was only 1.0%. The precipitation rates of cobalt, nickel, and copper were all greater than 99.5%.

[0032] (5) The above filtrate was extracted with P204 to remove trace amounts of calcium and magnesium ions, and then manganese and lithium were recovered respectively.

[0033] Example 2: The conditions were basically the same as in Example 1, except that the pH was controlled at 2.5, the ORP at 250 mV, and air bubbling was used instead of hydrogen peroxide as the redox potential adjuster. The final result showed a manganese loss rate of 1.8% and precipitation rates of cobalt, nickel, and copper all greater than 99.2%.

[0034] Example 3: A method for selectively separating and recovering valuable metals from ternary lithium battery cathode powder includes the following steps: (1) Take 1 kg of ternary battery black powder (NCM523) obtained by crushing and sorting, leach it with 2M sulfuric acid and an appropriate amount of hydrogen peroxide at 80℃ for 2 hours, and obtain leachate after solid-liquid separation. Add hydrogen peroxide to leachate and adjust the pH value to 4.5 with NaOH solution to precipitate and remove iron and aluminum, and obtain pretreated liquid. Analyze its composition: Mn 20g / L, Co 10g / L, Ni 12g / L, Li 3g / L, Cu 0.5g / L.

[0035] (2) The pretreated solution was transferred to a reactor equipped with a stirrer, an online pH meter, and an ORP meter. The pH of the solution was adjusted to 3.8 with dilute sulfuric acid. The ORP value of the system was stabilized at 320 mV by adding a small amount of hydrogen peroxide.

[0036] (3) Under vigorous stirring, slowly add a 1 mol / L sodium thiosulfate (Na2S2O3) solution. During the addition, maintain the pH at 3.8±0.1 and the ORP at 320±10mV by automatically adding acid / base and redox potential adjuster. The amount of sodium thiosulfate added is 10% of the total molar amount of sodium thiosulfate used. React for 20 min, and continue stirring and aging for 30 min.

[0037] (4) The pH of the reaction system was controlled to be 2.6 and the redox potential Eh to be 250mV. The remaining sodium thiosulfate solution was slowly added to the reaction. During the addition, the pH was maintained at 2.6±0.1 and the ORP at 250±10mV by automatically adding acid / base and redox potential adjuster. The total amount of sodium thiosulfate added was 1.1 times the theoretical amount. Stirring and aging continued for 30 minutes.

[0038] (5) After the reaction was completed, the mixture was filtered to obtain black sulfide slag and light pink filtrate. The calculated loss rate of manganese was only 0.7%. The precipitation rates of cobalt, nickel, and copper were all greater than 99.5%.

[0039] (6) The above filtrate was extracted with P204 to remove trace amounts of calcium and magnesium ions, and then manganese and lithium were recovered respectively.

[0040] Example 4: The conditions were basically the same as in Example 3, except that 0.1% sodium dodecylbenzenesulfonate by weight of the leachate was added in step (4). The final manganese loss rate was 0.6%, and the precipitation rates of cobalt, nickel, and copper were all greater than 99.6%.

[0041] Comparative Example 1: The conditions were basically the same as in Example 1, except that the pH value was controlled to be stable at 4.5, and the final loss rate of manganese was 3.9%, while the precipitation rates of cobalt, nickel and copper were all greater than 99.0%.

[0042] Comparative Example 2: The conditions were basically the same as in Example 1, except that the ORP value was controlled to be stable at 150mV, and the final loss rate of manganese was 3.7%, while the precipitation rates of cobalt, nickel and copper were all greater than 99.0%.

[0043] As can be seen from the above examples and comparative examples, controlling the pH and ORP values ​​to be stable is beneficial for the separation of manganese and nickel-cobalt, resulting in less loss of manganese.

Claims

1. A method for selectively separating and recovering valuable metals from ternary lithium battery cathode powder, characterized in that, Includes the following steps: (1) Leaching the positive electrode powder of a ternary battery to obtain a sample containing Mn 2+ Co 2+ Ni 2+ Cu 2+ Li + The leachate; (2) Control the pH of the leachate to 2.0-4.0, and simultaneously add a redox potential regulator to the leachate to control the redox potential Eh of the leachate to 200-350mV. Under the above conditions, slowly add the sulfiding agent to react and generate CoS, NiS and CuS precipitates, while Mn... 2+ The solution is retained; after the reaction is completed, the solid and liquid are separated to obtain a sulfide slag rich in cobalt, nickel, and copper, and a purified liquid containing manganese and lithium.

2. The method according to claim 1, characterized in that, Step (2) consists of two stages, as follows: First stage: Control the pH of the reaction system to 3.5-4.0, the redox potential Eh to 300-350mV, and slowly add the initial vulcanizing agent accounting for 10-30% of the total molar amount of the vulcanizing agent, and react for 5-30 minutes; Second stage: Control the pH of the reaction system to 2.5-3.0 and the redox potential Eh to 200-280mV, and slowly add the remaining sulfiding agent to complete the sulfidation precipitation reaction.

3. The method according to claim 2, characterized in that, In the second stage, a selective regulator is added to the reaction system. The selective regulator is at least one of a surfactant or a polymeric flocculant. The amount of the selective regulator added is 0.01-0.1% of the mass of the leachate.

4. The method according to claim 3, characterized in that, The surfactant is at least one of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate; the polymeric flocculant is at least one of polyacrylamide and sodium polyacrylate.

5. The method according to claim 2, characterized in that, There is a aging time of 10-30 minutes between the first and second stages.

6. The method according to claim 1, characterized in that, The redox potential modifier is one or more of hydrogen peroxide, air, or ozone.

7. The method according to claim 1, characterized in that, The reaction process was monitored and controlled in real time using an online pH meter and a redox potential meter to ensure the pH value and redox potential Eh of the reaction system.

8. The method according to claim 1, characterized in that, The sulfiding agent is sodium thiosulfate or sodium sulfide, and the total amount of the sulfiding agent added is 1.0-1.2 times the theoretical stoichiometry for complete precipitation of Co, Ni, and Cu.

9. The method according to claim 1, characterized in that, The leaching of the positive electrode powder of ternary lithium batteries is carried out using sulfuric acid and a reducing agent, wherein the reducing agent is hydrogen peroxide or sodium sulfite.

10. The method according to claim 1, characterized in that, The purified liquid containing manganese and lithium is subjected to deep purification to remove trace impurities, and manganese and lithium are recovered respectively; the deep purification is carried out by using P204 extractant to extract residual calcium and magnesium ions.