A method for extracting nickel and cobalt from a ternary electrode powder

Abstract

The application discloses a method for extracting nickel and cobalt from ternary electrode plate powder, and comprises the following steps: S1, raw material preparation; S2, CO reduction activation and in-situ pre-carbonation; S3, CO2 recovery; S4, first-stage normal-pressure selective carbonylation for nickel extraction; S5, second-stage pressurized selective carbonylation for cobalt extraction; S6, Ni(CO)4 gas thermal decomposition for preparing nickel powder; S7, Na[Co(CO)4] solution treatment for preparing cobalt products; and S8, carbonylation residue comprehensive recovery. The method realizes selective and efficient separation and recovery of nickel and cobalt through the combination of the processes of reduction-carbonylation in the same reactor in sequence with CO as the main gas source, in-situ pre-carbonation of CO2 for simplifying lithium extraction, step-by-step selective carbonylation and condensation / absorption separation, simultaneously recovers lithium by using reduction byproduct CO2, is short in technological process, mild in conditions, and reagent recycling is utilized, and is provided with safety engineering measures of the system.

Description

Technical Field

[0001] This invention relates to the technical field of waste lithium-ion battery recycling methods, and in particular to a method for extracting nickel and cobalt from ternary electrode powder. Background Technology

[0002] Ternary system (NCM, LiNi) x Co y Mn z Lithium-ion batteries (O2) are rapidly gaining market share due to their high energy density and good low-temperature performance. However, lithium batteries have a limited lifespan, and with the arrival of the retirement wave, a large number of retired ternary lithium-ion batteries will become typical "urban mines." Ternary cathode materials contain approximately 20%-30% nickel, 10%-20% cobalt and manganese, and 5%-7% lithium. These metal contents are far higher than in natural ores, making them highly valuable for recycling.

[0003] The recycling of spent ternary lithium-ion batteries typically involves discharging, dismantling, crushing, sorting, and pyrolyzing the individual battery cells to obtain a black powder, known as "black powder" or "electrode powder," which is a mixture of positive electrode active material (LiNiCoMnO2) and negative electrode carbon powder. Existing recycling technologies are mainly divided into two categories: hydrometallurgy and pyrometallurgy. Among these, the carbonyl process (also known as vapor phase metallurgy) has received considerable attention in recent years as a highly selective pyrometallurgical recycling technology.

[0004] (1) Basic Principles of the Carbonyl Method. The carbonyl method is based on the principle of the reaction between transition metals and carbon monoxide to generate volatile metal carbonyl compounds. Under suitable temperature and pressure, metals such as nickel, cobalt, and iron can react with CO to generate corresponding carbonyl compounds: Ni(CO)4 (boiling point 43.2℃), HCo(CO)4 (boiling point approximately -26.2℃), and Fe(CO)5 (boiling point 103.6℃). These carbonyl compounds have different boiling points and thermal stability, and can be separated by physicochemical methods such as evaporation, condensation, and absorption, and then thermally decomposed to obtain high-purity metals. Among them, the synthesis and thermal decomposition of Ni(CO)4 is the classic Mond process, which has been industrialized for over a century in factories such as Vale Clydach (UK), and is the only mature industrialized metal carbonyl system.

[0005] (2) BASF Reduction-Carbonization Process. Existing literature EP3885458 / CN115516120A (BASF) discloses a method for battery recycling through reduction and carbonylation: battery materials containing nickel oxide and / or cobalt compounds are reduced to elemental nickel and / or cobalt by heating above 350°C, and then carbonylated with carbon monoxide at 30–300°C and 1–300 bar to generate volatile carbonyl nickel and / or carbonyl cobalt, which are then separated from solid residues by evaporation. Step (1.1) of this patent indicates that reduction can be achieved by heating in an inert, hydrogen, or oxygen atmosphere, and in an inert atmosphere, it can be reduced by carbon or organic materials in the battery materials. This patent indicates that nickel and cobalt can be separated through stepwise carbonylation: first, nickel is carbonylated under non-reactive gas conditions, and then cobalt is carbonylated in the presence of a reactive gas (H2), or vice versa. Step (3.2) mentions that volatile carbonyl compounds can be purified and separated through adsorption, condensation, distillation, or vaporization, but does not specifically describe the separation process conditions. This patent treats reduction and carbonylation as two independent steps. After reduction, cooling is required before reheating for carbonylation, and the reduction atmosphere differs from the carbonylation atmosphere (inert / H2 / O2 for reduction, CO for carbonylation), resulting in gas switching. Data from the patent's examples show that under harsh conditions of 170–200°C and 200 bar, the Ni carbonylation rate of battery-grade black powder is only 18–23%, Co is only 14–19%, and the carbonylation rate of pure cobalt powder is only 1%, highlighting the problem of low cobalt carbonylation efficiency.

[0006] (3) Johnson Matthey Nickel Recovery Process. Existing literature WO2022038337 (Johnson Matthey) discloses a method for recovering nickel from waste battery materials: waste battery materials containing nickel compounds are reduced to metallic nickel in an H2 atmosphere at 500–900°C, then reacted with CO at 45–85°C and atmospheric pressure (or 140–200°C and 6–8 MPa high pressure) to generate Ni(CO)4, and finally Ni(CO)4 is reacted with sulfuric acid to generate NiSO4. This method only recovers nickel, directly abandoning the carbonylation recovery of cobalt, leaving the cobalt in the slag for separate treatment, resulting in a waste of cobalt resources. The reduction uses H2 and the carbonylation uses CO, which involves gas switching. This patent specifically warns that the condensation and accumulation of Ni(CO)4 in the scrubbing tower may lead to instantaneous decomposition and explosion, and safety constraints are strict.

[0007] (4) Tesla's carbonyl refining process. Existing literature WO2022140461 (Tesla) discloses a process for recovering materials from spent rechargeable lithium batteries: after reducing a mixture of electrode active materials at 300–1200°C, a first carbonylation (40–120°C, 15–2000 PSIG) is performed to generate Ni(CO)4, which is optionally distilled to separate iron carbonyl (Fe(CO)5), and then Ni(CO)4 is thermally decomposed to obtain nickel metal; subsequently, a second carbonylation (40–120°C, 800–2500 PSIG) is performed to recover cobalt, which is thermally decomposed to obtain cobalt metal. This patent indicates that the reduction can use "hydrogen, carbon-containing materials, hydrocarbon materials or combinations thereof", that is, the reducing agent can be carbonaceous materials (carbothermic reduction), but it does not disclose an integrated scheme using CO as the reducing gas. In this patent, distillation is only used to remove iron (when the raw material contains iron), and the separation of nickel and cobalt still depends on stepwise carbonylation and different pressure conditions. Reduction and carbonylation are two independent steps involving temperature and gas switching. Cobalt carbonylation requires high pressure of 800–2500 PSIG (approximately 5.5–17.2 MPa), which is a demanding process.

[0008] (5) Hydrogen reduction-water leaching lithium extraction process. China ENFI Engineering Technology Co., Ltd. proposed a new hydrogen reduction-water leaching process: using hydrogen to reduce the high-valence nickel, cobalt, and manganese in the cathode material at 450-550℃, dissociating and activating the lithium, and selectively recovering the lithium (in the form of LiOH) through water leaching, leaving the nickel, cobalt, and manganese in the slag. Under optimal process parameters, the lithium recovery rate can reach 95.8%. This process uses H2 reduction, which requires a separate water leaching lithium extraction step after reduction. Moreover, the water vapor generated by H2 reduction causes the reduction slag to clump, affecting subsequent processing.

[0009] Although the carbonyl method for recovering nickel and cobalt has advantages such as high selectivity and high product purity, existing technologies still have the following shortcomings: Defect 1: Reduction and carbonylation are performed in separate steps, resulting in complex gas switching and high energy consumption. In existing carbonylation processes, the reduction and carbonylation steps are two independent operating units. In the BASF patent, reduction is carried out at 350–900°C under an inert / H2 / O2 atmosphere, followed by carbonylation at 30–300°C under a CO atmosphere, requiring gas switching and temperature adjustments. In the Johnson Matthey patent, reduction uses H2 (500–900°C) and carbonylation uses CO (45–85°C), also requiring gas switching. The Tesla patent uses H2 or carbonaceous materials for reduction (300–1200°C) and carbonylation uses CO (40–120°C), also a two-step operation. Gas switching involves reactor purging and replacement, resulting in long process times, high energy consumption, and low equipment utilization. Furthermore, existing technologies primarily use H2 or inert atmospheres as reducing agents, failing to utilize the dual function of CO as both a reducing agent and a carbonylating reagent. Additionally, the CO2 from the reduction tail gas is not integrated with the lithium extraction process system, resulting in insufficient utilization of carbon resources.

[0010] Defect 2: Low or outright abandonment of cobalt carbonylation efficiency, resulting in insufficient cobalt recovery. Data from BASF patent examples show that under extremely harsh conditions—170–200°C, 200 bar, CO+H2 reaction gas, and 10 hours—the cocotylation rate of battery-reduced black powder is only 14–19%, and the carbonylation rate of pure cobalt powder is only 1%. This indicates that cobalt carbonylation itself has extremely slow kinetics, not simply insufficient conditions. Johnson Matthey's patent strategy is to directly abandon cobalt carbonylation recovery, only recovering nickel, leaving the cobalt in the slag for further processing, leading to a waste of cobalt resources. How to improve cobalt carbonylation efficiency and achieve selective cobalt recovery under lower pressure remains a challenge that current technologies have not yet solved.

[0011] Defect 3: Low efficiency or lack of engineering support for carbonyl compound separation methods. While the BASF patent mentions stepwise carbonylation, data from the examples show low separation efficiency of Ni and Co under co-carbonylation conditions. In the Tesla patent, distillation is only used for iron removal, failing to achieve simultaneous separation of the three carbonyl compounds (nickel, cobalt, and iron). HCo(CO)4, as a carbonyl compound of cobalt, has a boiling point (-26.2℃) much lower than Ni(CO)4 (43.2℃) and Fe(CO)5 (103.6℃). Theoretically, it could be separated using boiling point difference distillation. However, HCo(CO)4 requires CO pressure to maintain stability; it decomposes upon depressurization. Furthermore, there is no precedent for large-scale industrial application of HCo(CO)4, making pressurized distillation separation extremely difficult and risky in terms of engineering. Current technology lacks a practical separation scheme that can efficiently separate carbonyl compounds while avoiding the risks associated with HCo(CO)4 distillation.

[0012] Defect 4: The carbonylation conditions for cobalt are demanding. Cobalt carbonylation is more difficult than nickel carbonylation, requiring higher pressure and the presence of reactive gases. BASF's patent requires cobalt carbonylation to be carried out at high pressures of 50–300 bar and in the presence of reactive gases such as H2 or NO; Tesla's patent requires cobalt carbonylation at high pressures of 800–2500 PSIG (approximately 5.5–17.2 MPa). High-pressure operation equipment requires significant investment and carries high safety risks, limiting its industrial-scale application.

[0013] Defect 5: High reduction temperature and high energy consumption. The H2 reduction temperature in Johnson Matthey's patent is 500-900℃ (preferably 600-900℃), while the reduction temperature in Tesla's patent is 300-1200℃ (preferably 450-600℃ or 500-1000℃). The high reduction temperature leads to high energy consumption and high equipment requirements.

[0014] Defect 6: The integration of lithium recovery and carbonylation processes is unsystematic, requiring a separate water leaching step. While Tesla's patent describes lithium recovery via water / acid leaching after carbonylation, the description is rather brief. Existing carbonylation processes primarily focus on nickel and cobalt recovery, lacking a systematic design for comprehensive lithium recovery. Processes using H2 reduction require a separate water leaching step for lithium extraction, and the water vapor generated during H2 reduction causes the reduction slag to agglomerate, affecting subsequent processing. Furthermore, the CO2 in the reduction tail gas is not integrated with the lithium extraction process, resulting in underutilization of carbon resources.

[0015] Defect 7: Safety constraints for Ni(CO)4 are not systematically addressed. Ni(CO)4 is one of the most toxic metal carbonyl compounds known, with an IDLH (instantaneous risk to life and health) of 2 ppm, 600 times more toxic than CO. The OSHA permissible exposure limit is only 0.001 ppm (1 ppb), and it is a flammable liquid (flash point <23°C). Existing patented technologies do not adequately describe safety engineering measures for Ni(CO)4, lacking systematic engineering solutions such as closed-loop negative pressure, ppb-level online monitoring, and emergency decomposition.

[0016] In summary, there is an urgent need for a method for extracting nickel and cobalt from ternary electrode powder that can use CO as the main gas source to achieve sequential reduction-carbonylation in the same reactor, simplify the lithium extraction process through in-situ CO2 pre-carbonation, practically recover nickel and cobalt by stepwise selective carbonylation and condensation / absorption separation, have mild process conditions, achieve comprehensive recovery of valuable metals, and systematically address safety constraints. Summary of the Invention

[0017] To address the aforementioned technical problems, this invention provides a method for extracting nickel and cobalt from ternary electrode powder.

[0018] To achieve the above objectives, the technical solution of the present invention is as follows: A method for extracting nickel and cobalt from ternary electrode powder includes the following steps: S1. Raw material preparation: Remove the positive electrode active material LiNi from the discarded ternary lithium-ion batteries. x CoyMn z Ternary electrode powder containing O2 and negative electrode carbon powder; S2, CO reduction activation and in-situ precarbonation: The ternary electrode powder was placed in a reduction roasting furnace and reduced roasted in a mixed atmosphere mainly composed of carbon monoxide and containing 5-15 vol% hydrogen. The reduction roasting conditions were: reduction temperature 450-600℃, reduction time 1-3h, to obtain reduction slag and CO2. The reduction slag contained metallic nickel, metallic cobalt, metallic iron, MnO, Li2CO3, carbon powder and a small amount of impurities. S3 and CO2 recovery: The residual gas is discharged and CO2 is separated and recovered by a CO2 absorption device. Unreacted CO is compressed and returned to the reduction furnace or used directly in the subsequent carbonylation step. S4, First stage of selective carbonylation for nickel extraction under ambient pressure: The temperature inside the reduction roasting furnace is lowered to 50-80℃, and CO is introduced under a pressure of 0.1-0.5 MPa to carry out the first stage of carbonylation nickel extraction, generating Ni(CO)4 gas and solid residue. The reaction time is 2-12 hours. S5, Second-stage pressurized selective carbonylation for cobalt extraction The solid residue obtained in step S4 is subjected to a second stage of pressurized selective carbonylation under a mixed atmosphere of CO and 10-20 vol% H2, so that the cobalt metal is carbonylated to HCo(CO)4 and carried out with the gas flow. The CO pressure is 5-10 MPa, the reaction temperature is 150-200℃, and the reaction time is 4-24 h. After that, the HCo(CO)4 gas flow is introduced into the alkaline absorption tower and absorbed by NaOH or KOH alkaline solution with a concentration of 5-20 wt% under a CO pressurized atmosphere of 1-5 MPa to obtain Na[Co(CO)4] solution. Nickel powder is prepared by thermal decomposition of S6 and Ni(CO)4 gases; S7. Preparation of cobalt products by treating Na[Co(CO)4] solution; S8, comprehensive recovery of carbonylation residue The solid residue after the second carbonylation in step S5 is subjected to comprehensive recycling treatment.

[0019] In step S2, the reduction calcination conditions are: reduction temperature 500-550℃, reduction time 1.5-2h; and the volume percentage of H2 in the mixed atmosphere is 8-12 vol%.

[0020] In step S2, the reduction residue is leached with pressurized CO2 to leach Li2CO3. After solid-liquid separation, the leachate is heated and decomposed to recover the Li2CO3 product, yielding leaching residue containing Ni, Co, Fe, and MnO for subsequent carbonylation. The CO2 pressure is 0.5–2 MPa, the temperature is 20–60°C, and the heating decomposition temperature is 60–90°C. In step S3, the recovered CO2 is used for pressurized CO2 leaching to achieve internal recycling of CO2.

[0021] In step S3, the CO2 absorption device is an alkaline absorption device or a pressure swing adsorption device.

[0022] In step S4, the temperature inside the reduction calcination furnace is reduced to 55-70°C.

[0023] In step S5, the CO pressure is 5-8 MPa and the reaction temperature is 160-180℃.

[0024] In step S5, a carbonylation catalyst is added in an amount of 0.1% to 5% of the residue weight. The carbonylation catalyst is one or more of hydrogen sulfide, carbon disulfide, sulfur dioxide, and ammonia.

[0025] In step S5, if Fe(CO)5 is generated in the second stage, taking advantage of the fact that the boiling point of Fe(CO)5 (103.6℃) is much higher than that of HCo(CO)4 (-26.2℃), a temperature-controlled condenser is installed before the alkaline absorption tower to condense and liquefy Fe(CO)5, while HCo(CO)4 enters the alkaline absorption in a gaseous state. The temperature range of the temperature-controlled condenser is 0-20℃.

[0026] Specifically, step S6 involves directly introducing the Ni(CO)4 gas obtained in step S4 into the thermal decomposition reactor to avoid intermediate condensation and liquefaction, and performing thermal decomposition at 180–250°C to obtain high-purity nickel powder and CO gas. Alternatively, liquid Ni(CO)4 can be condensed and collected first, and then sent to the thermal decomposition reactor. Or, Ni(CO)4 can be reacted with sulfuric acid without thermal decomposition to generate NiSO4 product.

[0027] Specifically, step S7 involves further processing the (Na[Co(CO)4]) solution obtained from alkaline absorption in step S5 to prepare cobalt products. The subsequent processing technology is thermal oxidation decomposition to prepare Co2O3 / Co3O4, acidification precipitation to prepare Co(OH)2 / CoCO3, or direct preparation of CoSO4 products. Among them, the thermal oxidation decomposition to prepare Co2O3 / Co3O4 involves heating the absorbent to 80-120℃ and introducing air or oxygen to oxidize and decompose sodium cobalt carbonyl into Co3O4 precipitate, while releasing CO and CO2. After filtration, washing and drying, the Co3O4 precipitate is reduced to metallic cobalt powder by hydrogen at 400-600℃, or directly used as a cobalt oxide product. In the process of preparing Co(OH)2 / CoCO3 by acid precipitation, acid is added to the absorption liquid to adjust the pH to 8-9, so that cobalt precipitates in the form of Co(OH)2 or CoCO3. After filtration and washing, cobalt salt products are obtained, or it can be directly reacted with sulfuric acid to generate CoSO4 solution, and then CoSO4•7H2O products are obtained by evaporation and crystallization. One method involves directly preparing CoSO4 by reacting the absorbent with sulfuric acid to convert sodium cobalt carbonyl into CoSO4, while releasing CO and H2. After purification, evaporation, and crystallization, battery-grade CoSO4 is obtained. Step S8 includes: Cobalt recovery: Uncarbonylated cobalt in the residue is recovered by acid leaching. The leaching is carried out with sulfuric acid, with a liquid-to-solid ratio of 3:1 to 5:1, a temperature of 70 to 85°C, a time of 1 to 2 hours, and a pH of 1.5 to 2.5. Cobalt and manganese enter the leaching solution, and impurities are separated by precipitation through pH adjustment. Cobalt and manganese are separated by extraction from the leaching solution. CoSO4 or Co(OH)2 products are prepared from the cobalt solution, and MnSO4 products are prepared from the manganese solution. Iron recovery: The metallic iron in the acid leaching residue after the recovery of residual cobalt is separated by magnetic separation or recovered as FeSO4 by acid leaching; Lithium recovery: The reduction residue obtained in step S2 is slurried with water and pressurized with CO2, wherein the pressure is 0.5-2 MPa and the temperature is 20-60℃. Li2CO3 is converted into soluble LiHCO3. After solid-liquid separation, the leachate is heated and decomposed to recover Li2CO3 product. The CO2 comes from the reduction tail gas recovered in step S3 to realize internal CO2 circulation. The heating decomposition temperature is 60-90℃. Manganese recovery: Manganese exists in the form of MnO. In the residual cobalt recovery process, it enters the leaching solution together with cobalt. After extraction and separation, it is used to prepare MnSO4 or MnCO3 products.

[0028] The beneficial effects of this invention are: (1) This invention achieves selective and efficient separation and recovery of nickel and cobalt by using CO as the main gas source for reduction-carbonylation in the same reactor, CO2 in-situ precarbonization to simplify lithium extraction, stepwise selective carbonylation and condensation / absorption separation. At the same time, lithium is recovered by utilizing the reduction byproduct CO2. The process is short, the conditions are mild, the reagents are recycled, and a complete set of safety engineering measures are provided.

[0029] (2) In the CO reduction process of this invention, high-valence nickel and cobalt in the cathode material are reduced to elemental metals (zero valence state), manganese is reduced to MnO, and impurity iron is reduced to metallic iron. Lithium is dissociated from the stable layered structure Li(NiCoMn)O2 and converted into Li2O. At the same time, the CO2 byproduct generated by CO reduction reacts in situ with Li2O to generate lithium carbonate (Li2CO3), realizing in-situ pre-carbonization and fixation of lithium. The addition of H2 is used to suppress CO disproportionation (Boudouard reaction) carbon deposition and assist reduction. CO reduction destroys the crystal structure of the cathode material, and nickel and cobalt are converted into metallic states (zero valence state), and iron is converted into metallic iron, providing active metal precursors for subsequent carbonylation. Meanwhile, lithium is pre-fixed in the reduction slag in the form of Li2CO3, integrating the independent carbonization process in the traditional process into the reduction furnace, simplifying the subsequent lithium extraction process.

[0030] (3) In this invention, 5-15 vol% H2 is added to the reducing gas, and the balance of the CO / CO2 / CO+H2O system is adjusted by the water-gas shift reaction to suppress the thermodynamic driving force of the Boudouard reaction. At the same time, a fluidized bed or rotary kiln reactor is used to enhance gas-solid contact and avoid local CO concentration. It should be noted that although CO reduction avoids the sintering and agglomeration problem caused by water vapor generated by H2 reduction, Boudouard carbon deposits may bring agglomeration risk of different mechanisms. It must be controlled by the above-mentioned H2 ratio and CO / CO2 partial pressure ratio. A small amount of residual carbon deposits can participate in the reduction reaction as an auxiliary reducing agent or be discharged with carbonylation residue.

[0031] (4) In this invention, the role of CO2 in-situ precarbonation is to pre-convert Li2O / LiOH into Li2CO3, integrating the independent carbonization tower process in the traditional process into the reduction furnace, simplifying rather than completely eliminating the subsequent water leaching lithium extraction. The solubility of Li2CO3 in pure water at room temperature is limited, about 1.3 g / 100mL, and CO2 pressurized water leaching is required to improve the solubility.

[0032] (5) The present invention can complete CO reduction and the first stage carbonylation in the same reactor. After the CO reduction is completed, the gas source composition is not changed. CO is still the main gas source. The reactor is cooled to the carbonylation temperature, 50-80°C, and CO is introduced at 0.1-0.5 MPa to carry out the first stage carbonylation for nickel extraction. The reduction and the first stage carbonylation are carried out in the same reactor in sequence, without the need for intermediate furnace start-up, gas replacement and material transfer.

[0033] (6) This invention, by adding a catalyst and optimizing the H2 ratio, performs a second-stage carbonylation at 5–10 MPa. The expected Co carbonylation recovery rate is 30–50%, which is superior to the BASF patent level. The remaining 50–70% of cobalt remains in the carbonylation residue and is recovered by the acid leaching wet method in step S8. This invention does not require full recovery of cobalt carbonylation, but rather achieves comprehensive cobalt recovery through a combination of "cobalt extraction by carbonylation + cobalt recovery by wet method from residue". The total cobalt recovery rate can reach over 85%, which is significantly better than the BASF (14–19%) and Johnson Matthey (0%, abandoning cobalt recovery) schemes while maintaining process feasibility.

[0034] (7) This invention does not use pressurized distillation to separate HCo(CO)4 because the decomposition of HCo(CO)4 in the low-pressure zone of the distillation column will cause cobalt to deposit at the top of the column, which will disrupt the operation. Instead, it uses in-situ alkaline absorption to convert HCo(CO)4 into a stable cobalt carbonyl salt solution.

[0035] (8) The reduction-carbonylation process using CO as the main gas source is carried out sequentially in the same reactor, eliminating the need for gas source switching and significantly shortening the process flow. This invention uses CO as the main gas source (containing a small amount of H2 to inhibit carbon deposition). After reduction, the gas source composition is not changed; the temperature is directly lowered to 50–80°C for the first stage of atmospheric pressure carbonylation to extract nickel, achieving sequential reduction and the first stage of carbonylation in the same reactor. Compared to existing technologies where reduction and carbonylation are carried out step-by-step, requiring gas switching and temperature adjustments (BASF requires inert / H2 reduction followed by switching to CO carbonylation, and JM requires H2 reduction followed by switching to CO carbonylation), this invention eliminates the need to switch the gas source system, significantly shortening the process flow, increasing equipment utilization, and reducing energy consumption.

[0036] (9) CO2 in-situ precarbonation simplifies the lithium extraction process, and CO2 is recycled internally. This invention utilizes the in-situ reaction of CO2, a byproduct of CO reduction, with Li2O to generate Li2CO3, integrating the independent carbonization tower process in the traditional process into the reduction furnace, thus simplifying the subsequent water leaching lithium extraction process. Lithium extraction is carried out using pressurized CO2 water leaching (Li2CO3+CO2+H2O→2LiHCO3), with CO2 recovered from the reduction tail gas, realizing the internal recycling of CO2 and reducing the purchase and emission of CO2.

[0037] (10) Stepwise selective carbonylation achieves efficient separation of nickel and cobalt under mild process conditions. This invention employs stepwise selective carbonylation: the first stage selectively extracts nickel at atmospheric pressure (0.1–0.5 MPa) and 50–80°C (the industrial conditions of the Mond process for over a century), leaving cobalt and iron residues; the second stage extracts cobalt at 5–10 MPa and 150–200°C. Compared to the low cocarbonylation efficiency of existing technologies (BASF achieves only 18–23% Ni and 14–19% Co at 200 bar), this invention achieves efficient nickel extraction under mild atmospheric pressure conditions and cobalt extraction under moderate pressure (5–10 MPa, far lower than BASF's 200 bar and Tesla's 800–2500 PSIG) through stepwise selective carbonylation.

[0038] (11) In-situ absorption of alkaline solution replaces distillation separation of HCo(CO)4, avoiding engineering risks. Given that HCo(CO)4 requires CO pressure to maintain stability, decomposes upon depressurization, and there is no precedent for large-scale industrial application, this invention does not use pressurized distillation to separate HCo(CO)4. Instead, it uses alkaline solution (NaOH) to absorb HCo(CO)4 in-situ under a CO pressurized atmosphere to generate a stable sodium cobalt carbonyl solution, which is then processed to prepare cobalt products. This scheme avoids engineering risks such as decomposition in the low-pressure zone of the HCo(CO)4 distillation column, cobalt deposition, and the entire pressure vessel being under a CO atmosphere. Furthermore, it is simple to operate and highly safe.

[0039] (12) The overall cobalt recovery rate is significantly better than that of existing technologies. The cobalt recovery rate of the second-stage pressurized carbonylation extraction in this invention is expected to be 30-50% (better than the 14-19% of the BASF patent). The remaining cobalt is recovered by the residue acid leaching wet method, and the total cobalt recovery rate can reach more than 85%. Compared with the Johnson Matthey patent, which directly abandons cobalt carbonylation recovery (cobalt recovery rate of 0%), this invention achieves effective cobalt recovery.

[0040] (13) Ni(CO)4 gas phase is directly fed into thermal decomposition to avoid the safety risks of liquid accumulation. In this invention, the Ni(CO)4 gas generated in the first stage carbonylation is directly fed into the thermal decomposition reactor. Referring to the industrial practice of the Mond process, it is ensured that Ni(CO)4 is in the gaseous state and above the boiling point throughout the process, avoiding the explosion risk caused by the accumulation of liquid Ni(CO)4 (JM patent warns that the accumulation of liquid Ni(CO)4 may decompose and explode instantly).

[0041] (14) Low reduction temperature and low energy consumption. The present invention uses CO reduction to reduce nickel and cobalt to a metallic state at 450-600℃. Compared with the existing technologies of 500-900℃ (JM) and 500-1000℃ (Tesla), the reduction temperature is reduced, which significantly reduces energy consumption.

[0042] (15) Closed-loop recycling of CO and H2 with no waste liquid discharge. The CO and H2 required for carbonylation are released during the thermal decomposition and alkaline absorption processes and then compressed and returned to the reduction furnace or carbonylation reactor for recycling. CO serves both the reduction and carbonylation steps, resulting in high gas utilization. The entire process does not produce waste liquid containing heavy metals (the leachate from the residual acid leaching process can be recycled after extraction and separation), making it green and environmentally friendly.

[0043] (16) Comprehensive recycling of valuable metals. This invention can simultaneously recover five valuable metal products: nickel (nickel powder or NiSO4), cobalt (Co2O3 / CoSO4, etc.), iron (iron powder or FeSO4), lithium (Li2CO3), and manganese (MnCO3 or MnSO4), with high resource utilization rate.

[0044] (17) The process conditions are relatively mild. Compared with the existing technology that requires 50-300 bar (BASF) and 800-2500 PSIG (Tesla) for cobalt carbonylation, the second stage of cobalt extraction in this invention only requires 5-10 MPa, and the first stage of nickel extraction is carried out under normal pressure. The pressure conditions are relatively mild, and the equipment investment and safety risks are reduced. Attached Figure Description

[0045] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of the invention.

[0047] Example 1 like Figure 1 As shown, a method for extracting nickel and cobalt from ternary electrode powder includes the following steps: S1. Raw material preparation: Remove the positive electrode active material LiNi from the discarded ternary lithium-ion batteries. x CoyMn z Ternary electrode powder containing O2 and negative electrode carbon powder; S2, CO reduction activation and in-situ precarbonation: The ternary electrode powder was placed in a reduction roasting furnace and reduced roasted in a mixed atmosphere mainly composed of carbon monoxide and containing 5 vol% hydrogen. The reduction roasting conditions were: reduction temperature 450℃, reduction time 1h, to obtain reduction slag and CO2. The reduction slag contained metallic nickel, metallic cobalt, metallic iron, MnO, Li2CO3, carbon powder and a small amount of impurities. S3 and CO2 recovery: The residual gas is discharged and CO2 is separated and recovered by a CO2 absorption device. Unreacted CO is compressed and returned to the reduction furnace or used directly in the subsequent carbonylation step. S4, First stage of selective carbonylation for nickel extraction under ambient pressure: The temperature inside the reduction roasting furnace was lowered to 50°C, and CO was introduced under a pressure of 0.1 MPa to carry out the first stage of carbonylation nickel extraction, generating Ni(CO)4 gas and solid residue. The reaction time was 2 hours. S5, Second-stage pressurized selective carbonylation for cobalt extraction The solid residue obtained in step S4 is subjected to a second stage of pressurized selective carbonylation under a mixed atmosphere of CO and 10 vol% H2, so that the cobalt metal is carbonylated to HCo(CO)4 and carried out with the gas flow. The CO pressure is 5 MPa, the reaction temperature is 150℃, and the reaction time is 4 h. After that, the HCo(CO)4 gas flow is introduced into the alkaline absorption tower and absorbed by 5 wt% NaOH or KOH alkaline solution under a CO pressurized atmosphere of 1 MPa to obtain Na[Co(CO)4] solution. Nickel powder is prepared by thermal decomposition of S6 and Ni(CO)4 gases; S7. Preparation of cobalt products by treating Na[Co(CO)4] solution; S8, comprehensive recovery of carbonylation residue The solid residue after the second carbonylation in step S5 is subjected to comprehensive recycling treatment.

[0048] Specifically, step S6 involves directly introducing the Ni(CO)4 gas obtained in step S4 into the thermal decomposition reactor to avoid intermediate condensation and liquefaction, and thermally decomposing it at 180°C to obtain high-purity nickel powder and CO gas. Alternatively, liquid Ni(CO)4 can be condensed and collected first, and then sent to the thermal decomposition reactor. Or, Ni(CO)4 can be thermally decomposed but reacted with sulfuric acid to generate NiSO4 product.

[0049] Specifically, step S7 involves further processing the (Na[Co(CO)4]) solution obtained from alkaline absorption in step S5 to prepare cobalt products. The subsequent processing technology is thermal oxidation decomposition to prepare Co2O3 / Co3O4, acidification precipitation to prepare Co(OH)2 / CoCO3, or direct preparation of CoSO4 products. Among them, the thermal oxidation decomposition to prepare Co2O3 / Co3O4 involves heating the absorbent to 80°C and introducing air or oxygen to oxidize and decompose sodium cobalt carbonyl into Co3O4 precipitate, while releasing CO and CO2. After filtration, washing and drying, the Co3O4 precipitate is reduced to metallic cobalt powder by hydrogen at 400°C, or directly used as a cobalt oxide product. In the process of preparing Co(OH)2 / CoCO3 by acid precipitation, acid is added to the absorption liquid to adjust the pH to 8, so that cobalt precipitates in the form of Co(OH)2 or CoCO3. After filtration and washing, cobalt salt products are obtained, or it can be directly reacted with sulfuric acid to generate CoSO4 solution, and then CoSO4•7H2O products are obtained by evaporation and crystallization. One method involves directly preparing CoSO4 by reacting the absorbent with sulfuric acid to convert sodium cobalt carbonyl into CoSO4, while releasing CO and H2. After purification, evaporation, and crystallization, battery-grade CoSO4 is obtained. Step S8 includes: Cobalt recovery: Uncarbonylated cobalt in the residue is recovered by acid leaching. The leaching is carried out with sulfuric acid at a liquid-to-solid ratio of 3:1, a temperature of 70℃, a time of 1 hour, and a pH of 1.5. Cobalt and manganese enter the leaching solution, and impurities are separated by precipitation through pH adjustment. Cobalt and manganese are separated by extraction from the leaching solution. CoSO4 or Co(OH)2 products are prepared from the cobalt solution, and MnSO4 products are prepared from the manganese solution. Iron recovery: The metallic iron in the acid leaching residue after the recovery of residual cobalt is separated by magnetic separation or recovered as FeSO4 by acid leaching; Lithium recovery: The reduction residue obtained in step S2 is slurried with water and pressurized with CO2. The pressure is 0.5 MPa and the temperature is 20℃. Li2CO3 is converted into soluble LiHCO3. After solid-liquid separation, the leachate is heated and decomposed to recover Li2CO3 product. The CO2 comes from the reduction tail gas recovered in step S3, realizing internal circulation of CO2. The heating decomposition temperature is 60℃. Manganese recovery: Manganese exists in the form of MnO. In the residual cobalt recovery process, it enters the leaching solution together with cobalt. After extraction and separation, it is used to prepare MnSO4 or MnCO3 products.

[0050] Example 2 like Figure 1 As shown, a method for extracting nickel and cobalt from ternary electrode powder includes the following steps: S1. Raw material preparation: Remove the positive electrode active material LiNi from the discarded ternary lithium-ion batteries. x CoyMn z Ternary electrode powder containing O2 and negative electrode carbon powder; S2, CO reduction activation and in-situ precarbonation: The ternary electrode powder was placed in a reduction roasting furnace and reduced roasted in a mixed atmosphere mainly composed of carbon monoxide and containing 15 vol% hydrogen. The reduction roasting conditions were: reduction temperature 600℃ and reduction time 3h, to obtain reduction slag and CO2. The reduction slag contained metallic nickel, metallic cobalt, metallic iron, MnO, Li2CO3, carbon powder and a small amount of impurities. S3 and CO2 recovery: The residual gas is discharged and CO2 is separated and recovered by a CO2 absorption device. Unreacted CO is compressed and returned to the reduction furnace or used directly in the subsequent carbonylation step. S4, First stage of selective carbonylation for nickel extraction under ambient pressure: The temperature inside the reduction roasting furnace was lowered to 80℃, and CO was introduced under a pressure of 0.5 MPa to carry out the first stage of carbonylation nickel extraction, generating Ni(CO)4 gas and solid residue. The reaction time was 12 hours. S5, Second-stage pressurized selective carbonylation for cobalt extraction The solid residue obtained in step S4 is subjected to a second stage of pressurized selective carbonylation under a mixed atmosphere of CO and 20 vol% H2, so that the cobalt metal is carbonylated to HCo(CO)4 and carried out with the gas flow. The CO pressure is 10 MPa, the reaction temperature is 200℃, and the reaction time is 24 h. After that, the HCo(CO)4 gas flow is introduced into the alkaline absorption tower and absorbed by 20 wt% NaOH or KOH alkaline solution under a CO pressurized atmosphere of 5 MPa to obtain Na[Co(CO)4] solution. Nickel powder is prepared by thermal decomposition of S6 and Ni(CO)4 gases; S7. Preparation of cobalt products by treating Na[Co(CO)4] solution; S8, comprehensive recovery of carbonylation residue The solid residue after the second carbonylation in step S5 is subjected to comprehensive recycling treatment.

[0051] Specifically, step S6 involves directly introducing the Ni(CO)4 gas obtained in step S4 into the thermal decomposition reactor to avoid intermediate condensation and liquefaction, and then thermally decomposing it at 250°C to obtain high-purity nickel powder and CO gas. Alternatively, liquid Ni(CO)4 can be condensed and collected first, and then sent to the thermal decomposition reactor. Or, Ni(CO)4 can be thermally decomposed but reacted with sulfuric acid to generate NiSO4 product.

[0052] Specifically, step S7 involves further processing the (Na[Co(CO)4]) solution obtained from alkaline absorption in step S5 to prepare cobalt products. The subsequent processing technology is thermal oxidation decomposition to prepare Co2O3 / Co3O4, acidification precipitation to prepare Co(OH)2 / CoCO3, or direct preparation of CoSO4 products. Among them, the thermal oxidation decomposition to prepare Co2O3 / Co3O4 involves heating the absorbent to 120°C and introducing air or oxygen to oxidize and decompose sodium cobalt carbonyl into Co3O4 precipitate, while releasing CO and CO2. After filtration, washing and drying, the Co3O4 precipitate is reduced to metallic cobalt powder by hydrogen at 600°C, or directly used as a cobalt oxide product. In the process of preparing Co(OH)2 / CoCO3 by acid precipitation, acid is added to the absorption liquid to adjust the pH to 9, so that cobalt precipitates in the form of Co(OH)2 or CoCO3. After filtration and washing, cobalt salt products are obtained, or it can be directly reacted with sulfuric acid to generate CoSO4 solution, and then CoSO4•7H2O products are obtained by evaporation and crystallization. One method involves directly preparing CoSO4 by reacting the absorbent with sulfuric acid to convert sodium cobalt carbonyl into CoSO4, while releasing CO and H2. After purification, evaporation, and crystallization, battery-grade CoSO4 is obtained. Step S8 includes: Cobalt recovery: Uncarbonylated cobalt in the residue is recovered by acid leaching. The leaching is carried out with sulfuric acid at a liquid-to-solid ratio of 5:1, a temperature of 85℃, a time of 2 hours, and a pH of 2.5. Cobalt and manganese enter the leaching solution, and impurities are separated by precipitation through pH adjustment. Cobalt and manganese are separated by extraction from the leaching solution. CoSO4 or Co(OH)2 products are prepared from the cobalt solution, and MnSO4 products are prepared from the manganese solution. Iron recovery: The metallic iron in the acid leaching residue after the recovery of residual cobalt is separated by magnetic separation or recovered as FeSO4 by acid leaching; Lithium recovery: The reduction residue obtained in step S2 is slurried with water, and CO2 is introduced and pressurized. The pressure is 2 MPa and the temperature is 60℃. Li2CO3 is converted into soluble LiHCO3. After solid-liquid separation, the leachate is heated and decomposed to recover Li2CO3 product. The CO2 comes from the reduction tail gas recovered in step S3, realizing internal circulation of CO2. The heating decomposition temperature is 90℃. Manganese recovery: Manganese exists in the form of MnO. In the residual cobalt recovery process, it enters the leaching solution together with cobalt. After extraction and separation, it is used to prepare MnSO4 or MnCO3 products.

[0053] Example 3 like Figure 1 As shown, a method for extracting nickel and cobalt from ternary electrode powder includes the following steps: S1. Raw material preparation: Remove the positive electrode active material LiNi from the discarded ternary lithium-ion batteries. x CoyMn z Ternary electrode powder containing O2 and negative electrode carbon powder; S2, CO reduction activation and in-situ precarbonation: The ternary electrode powder is placed in a reduction roasting furnace and reduced roasted in a mixed atmosphere of carbon monoxide and hydrogen to obtain reduction slag and CO2. The reduction slag contains metallic nickel, metallic cobalt, metallic iron, MnO, Li2CO3, carbon powder and a small amount of impurities. S3 and CO2 recovery: The residual gas is discharged and CO2 is separated and recovered by a CO2 absorption device. Unreacted CO is compressed and returned to the reduction furnace or used directly in the subsequent carbonylation step. S4, First stage of selective carbonylation for nickel extraction under ambient pressure: The temperature inside the reduction roasting furnace was lowered to 70℃, and CO was introduced under a pressure of 0.5 MPa to carry out the first stage of carbonylation nickel extraction, generating Ni(CO)4 gas and solid residue. The reaction time was 12 hours. S5, Second-stage pressurized selective carbonylation for cobalt extraction The solid residue obtained in step S4 is subjected to a second stage of pressurized selective carbonylation under a mixed atmosphere of CO and 20 vol% H2, so that the cobalt metal is carbonylated to HCo(CO)4 and carried out with the gas flow. The reaction time is 24 h. After that, the HCo(CO)4 gas flow is introduced into the alkaline absorption tower and absorbed by 20 wt% NaOH or KOH alkaline solution under a CO pressurized atmosphere of 5 MPa to obtain Na[Co(CO)4] solution. Nickel powder is prepared by thermal decomposition of S6 and Ni(CO)4 gases; S7. Preparation of cobalt products by treating Na[Co(CO)4] solution; S8, comprehensive recovery of carbonylation residue The solid residue after the second carbonylation in step S5 is subjected to comprehensive recycling treatment.

[0054] In step S2, the reduction calcination conditions are: reduction temperature 550℃, reduction time 2h; and the volume percentage of H2 in the mixed atmosphere is 12 vol%.

[0055] In step S3, the CO2 absorption device is an alkaline absorption device or a pressure swing adsorption device.

[0056] In step S5, the CO pressure is 8 MPa and the reaction temperature is 180℃.

[0057] In step S5, a carbonylation catalyst is added at a rate of 5% of the residue weight, wherein the carbonylation catalyst is carbon disulfide.

[0058] In step S5, if Fe(CO)5 is generated in the second stage, taking advantage of the fact that the boiling point of Fe(CO)5 (103.6℃) is much higher than that of HCo(CO)4 (-26.2℃), a temperature-controlled condenser is installed before the alkaline absorption tower to condense and liquefy Fe(CO)5, while HCo(CO)4 enters the alkaline absorption in a gaseous state. The temperature range of the temperature-controlled condenser is 0-20℃.

[0059] Example 4 like Figure 1 As shown, a method for extracting nickel and cobalt from ternary electrode powder includes the following steps: S1. Raw material preparation: Remove the positive electrode active material LiNi from the discarded ternary lithium-ion batteries. x CoyMn z Ternary electrode powder containing O2 and negative electrode carbon powder; S2, CO reduction activation and in-situ precarbonation: The ternary electrode powder is placed in a reduction roasting furnace and reduced roasted in a mixed atmosphere of carbon monoxide and hydrogen to obtain reduction slag and CO2. The reduction slag contains metallic nickel, metallic cobalt, metallic iron, MnO, Li2CO3, carbon powder and a small amount of impurities. S3 and CO2 recovery: The residual gas is discharged and CO2 is separated and recovered by a CO2 absorption device. Unreacted CO is compressed and returned to the reduction furnace or used directly in the subsequent carbonylation step. S4, First stage of selective carbonylation for nickel extraction under ambient pressure: The temperature inside the reduction roasting furnace was lowered to 55°C, and CO was introduced under a pressure of 0.1 MPa to carry out the first stage of carbonylation nickel extraction, generating Ni(CO)4 gas and solid residue. The reaction time was 2 hours. S5, Second-stage pressurized selective carbonylation for cobalt extraction The solid residue obtained in step S4 is subjected to a second stage of pressurized selective carbonylation under a mixed atmosphere of CO and 10 vol% H2, so that the cobalt metal is carbonylated to HCo(CO)4 and carried out with the gas flow. The reaction time is 4 h. After that, the HCo(CO)4 gas flow is introduced into the alkaline absorption tower and absorbed by 5 wt% NaOH or KOH alkaline solution under a CO pressurized atmosphere of 1 MPa to obtain Na[Co(CO)4] solution. Nickel powder is prepared by thermal decomposition of S6 and Ni(CO)4 gases; S7. Preparation of cobalt products by treating Na[Co(CO)4] solution; S8, comprehensive recovery of carbonylation residue The solid residue after the second carbonylation in step S5 is subjected to comprehensive recycling treatment.

[0060] In step S2, the reduction calcination conditions are: reduction temperature 500℃, reduction time 1.5h; and the volume percentage of H2 in the mixed atmosphere is 8 vol%.

[0061] In step S3, the CO2 absorption device is an alkaline absorption device or a pressure swing adsorption device.

[0062] In step S5, the CO pressure is 5 MPa and the reaction temperature is 160℃.

[0063] In step S5, a carbonylation catalyst is added at an amount of 0.1% of the residue weight, wherein the carbonylation catalyst is hydrogen sulfide.

[0064] In step S5, if Fe(CO)5 is generated in the second stage, taking advantage of the fact that the boiling point of Fe(CO)5 (103.6℃) is much higher than that of HCo(CO)4 (-26.2℃), a temperature-controlled condenser is installed before the alkaline absorption tower to condense and liquefy Fe(CO)5, while HCo(CO)4 enters the alkaline absorption in a gaseous state. The temperature range of the temperature-controlled condenser is 0-20℃.

[0065] Example 5 like Figure 1 As shown, a method for extracting nickel and cobalt from ternary electrode powder includes the following steps: S1. Raw material preparation: Remove the positive electrode active material LiNi from the discarded ternary lithium-ion batteries. xCoyMn z Ternary electrode powder containing O2 and negative electrode carbon powder; S2, CO reduction activation and in-situ precarbonation: The ternary electrode powder was placed in a reduction roasting furnace and reduced roasted in a mixed atmosphere mainly composed of carbon monoxide and containing 5 vol% hydrogen. The reduction roasting conditions were: reduction temperature 450℃, reduction time 1h, to obtain reduction slag and CO2. The reduction slag contained metallic nickel, metallic cobalt, metallic iron, MnO, Li2CO3, carbon powder and a small amount of impurities. S3 and CO2 recovery: The residual gas is discharged and CO2 is separated and recovered by a CO2 absorption device. Unreacted CO is compressed and returned to the reduction furnace or used directly in the subsequent carbonylation step. S4, First stage of selective carbonylation for nickel extraction under ambient pressure: The temperature inside the reduction roasting furnace was lowered to 50°C, and CO was introduced under a pressure of 0.1 MPa to carry out the first stage of carbonylation nickel extraction, generating Ni(CO)4 gas and solid residue. The reaction time was 2 hours. S5, Second-stage pressurized selective carbonylation for cobalt extraction The solid residue obtained in step S4 is subjected to a second stage of pressurized selective carbonylation under a mixed atmosphere of CO and 10 vol% H2, so that the cobalt metal is carbonylated to HCo(CO)4 and carried out with the gas flow. The CO pressure is 5 MPa, the reaction temperature is 150℃, and the reaction time is 4 h. After that, the HCo(CO)4 gas flow is introduced into the alkaline absorption tower and absorbed by 5 wt% NaOH or KOH alkaline solution under a CO pressurized atmosphere of 1 MPa to obtain Na[Co(CO)4] solution. Nickel powder is prepared by thermal decomposition of S6 and Ni(CO)4 gases; S7. Preparation of cobalt products by treating Na[Co(CO)4] solution; S8, comprehensive recovery of carbonylation residue The solid residue after the second carbonylation in step S5 is subjected to comprehensive recycling treatment.

[0066] In step S2, the reduction residue is leached with pressurized CO2 to leach Li2CO3. After solid-liquid separation, the leachate is heated and decomposed to recover the Li2CO3 product, yielding leaching residue containing Ni, Co, Fe, and MnO for subsequent carbonylation. The CO2 pressure is 0.5 MPa, the temperature is 20°C, and the heating decomposition temperature is 60°C. In step S3, the recovered CO2 is used for pressurized CO2 leaching to achieve internal recycling of CO2.

[0067] Example 6 like Figure 1As shown, a method for extracting nickel and cobalt from ternary electrode powder includes the following steps: S1. Raw material preparation: Remove the positive electrode active material LiNi from the discarded ternary lithium-ion batteries. x CoyMn z Ternary electrode powder containing O2 and negative electrode carbon powder; S2, CO reduction activation and in-situ precarbonation: The ternary electrode powder was placed in a reduction roasting furnace and reduced roasted in a mixed atmosphere mainly composed of carbon monoxide and containing 15 vol% hydrogen. The reduction roasting conditions were: reduction temperature 600℃ and reduction time 3h, to obtain reduction slag and CO2. The reduction slag contained metallic nickel, metallic cobalt, metallic iron, MnO, Li2CO3, carbon powder and a small amount of impurities. S3 and CO2 recovery: The residual gas is discharged and CO2 is separated and recovered by a CO2 absorption device. Unreacted CO is compressed and returned to the reduction furnace or used directly in the subsequent carbonylation step. S4, First stage of selective carbonylation for nickel extraction under ambient pressure: The temperature inside the reduction roasting furnace was lowered to 80℃, and CO was introduced under a pressure of 0.5 MPa to carry out the first stage of carbonylation nickel extraction, generating Ni(CO)4 gas and solid residue. The reaction time was 12 hours. S5, Second-stage pressurized selective carbonylation for cobalt extraction The solid residue obtained in step S4 is subjected to a second stage of pressurized selective carbonylation under a mixed atmosphere of CO and 20 vol% H2, so that the cobalt metal is carbonylated to HCo(CO)4 and carried out with the gas flow. The CO pressure is 10 MPa, the reaction temperature is 200℃, and the reaction time is 24 h. After that, the HCo(CO)4 gas flow is introduced into the alkaline absorption tower and absorbed by 20 wt% NaOH or KOH alkaline solution under a CO pressurized atmosphere of 5 MPa to obtain Na[Co(CO)4] solution. Nickel powder is prepared by thermal decomposition of S6 and Ni(CO)4 gases; S7. Preparation of cobalt products by treating Na[Co(CO)4] solution; S8, comprehensive recovery of carbonylation residue The solid residue after the second carbonylation in step S5 is subjected to comprehensive recycling treatment.

[0068] In step S2, the reduction residue is leached with pressurized CO2 to leach Li2CO3. After solid-liquid separation, the leachate is heated and decomposed to recover the Li2CO3 product, yielding leaching residue containing Ni, Co, Fe, and MnO for subsequent carbonylation. The CO2 pressure is 2 MPa, the temperature is 60℃, and the heating decomposition temperature is 90℃. In step S3, the recovered CO2 is used for pressurized CO2 leaching to achieve internal recycling of CO2.

[0069] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A method for extracting nickel and cobalt from ternary electrode powder, characterized in that, Includes the following steps: S1. Raw material preparation: Remove the positive electrode active material LiNi from the discarded ternary lithium-ion batteries. x CoyMn z Ternary electrode powder containing O2 and negative electrode carbon powder; S2, CO reduction activation and in-situ precarbonation: The ternary electrode powder was placed in a reduction roasting furnace and reduced roasted in a mixed atmosphere mainly composed of carbon monoxide and containing 5-15 vol% hydrogen. The reduction roasting conditions were: reduction temperature 450-600℃, reduction time 1-3h, to obtain reduction slag and CO2. The reduction slag contained metallic nickel, metallic cobalt, metallic iron, MnO, Li2CO3, carbon powder and a small amount of impurities. S3 and CO2 recovery: The residual gas is discharged and CO2 is separated and recovered by a CO2 absorption device. Unreacted CO is compressed and returned to the reduction furnace or used directly in the subsequent carbonylation step. S4, First stage of selective carbonylation for nickel extraction under ambient pressure: The temperature inside the reduction roasting furnace is lowered to 50-80℃, and CO is introduced under a pressure of 0.1-0.5 MPa to carry out the first stage of carbonylation nickel extraction, generating Ni(CO)4 gas and solid residue. The reaction time is 2-12 hours. S5, Second-stage pressurized selective carbonylation for cobalt extraction The solid residue obtained in step S4 is subjected to a second stage of pressurized selective carbonylation under a mixed atmosphere of CO and 10-20 vol% H2, so that the cobalt metal is carbonylated to HCo(CO)4 and carried out with the gas flow. The CO pressure is 5-10 MPa, the reaction temperature is 150-200℃, and the reaction time is 4-24 h. After that, the HCo(CO)4 gas flow is introduced into the alkaline absorption tower and absorbed by NaOH or KOH alkaline solution with a concentration of 5-20 wt% under a CO pressurized atmosphere of 1-5 MPa to obtain Na[Co(CO)4] solution. Nickel powder is prepared by thermal decomposition of S6 and Ni(CO)4 gases; S7. Preparation of cobalt products by treating Na[Co(CO)4] solution; S8, comprehensive recovery of carbonylation residue The solid residue after the second carbonylation in step S5 is subjected to comprehensive recycling treatment.

2. The method for extracting nickel and cobalt from ternary electrode powder according to claim 1, characterized in that, In step S2, the reduction calcination conditions are: reduction temperature 500-550℃, reduction time 1.5-2h; and the volume percentage of H2 in the mixed atmosphere is 8-12 vol%.

3. The method for extracting nickel and cobalt from ternary electrode powder according to claim 1, characterized in that, In step S2, the reduction residue is leached with pressurized CO2 to leach Li2CO3. After solid-liquid separation, the leachate is heated and decomposed to recover the Li2CO3 product, yielding leaching residue containing Ni, Co, Fe, and MnO for subsequent carbonylation. The CO2 pressure is 0.5–2 MPa, the temperature is 20–60°C, and the heating decomposition temperature is 60–90°C. The CO2 recovered in step S3 is used for pressurized CO2 leaching to achieve internal recycling of CO2.

4. The method for extracting nickel and cobalt from ternary electrode powder according to claim 1, characterized in that, In step S3, the CO2 absorption device is an alkaline absorption device or a pressure swing adsorption device.

5. The method for extracting nickel and cobalt from ternary electrode powder according to claim 1, characterized in that, In step S4, the temperature inside the reduction roasting furnace is reduced to 55-70°C.

6. The method for extracting nickel and cobalt from ternary electrode powder according to claim 1, characterized in that, In step S5, the CO pressure is 5-8 MPa and the reaction temperature is 160-180℃.

7. The method for extracting nickel and cobalt from ternary electrode powder according to claim 1, characterized in that, In step S5, a carbonylation catalyst is added in an amount of 0.1% to 5% of the residue weight. The carbonylation catalyst is one or more of hydrogen sulfide, carbon disulfide, sulfur dioxide, and ammonia.

8. The method for extracting nickel and cobalt from ternary electrode powder according to claim 1, characterized in that, In step S5, if Fe(CO)5 is generated in the second stage, taking advantage of the fact that the boiling point of Fe(CO)5 (103.6℃) is much higher than that of HCo(CO)4 (-26.2℃), a temperature-controlled condenser is installed before the alkaline absorption tower to condense and liquefy Fe(CO)5 and separate it, while HCo(CO)4 enters the alkaline absorption in a gaseous state. The temperature range of the temperature-controlled condenser is 0 to 20℃.

9. The method for extracting nickel and cobalt from ternary electrode powder according to claim 1, characterized in that, Specifically, step S6 involves directly introducing the Ni(CO)4 gas obtained in step S4 into the thermal decomposition reactor to avoid intermediate condensation and liquefaction, and then thermally decomposing it at 180–250°C to obtain high-purity nickel powder and CO gas. Alternatively, liquid Ni(CO)4 can be condensed and collected first, and then sent to the thermal decomposition reactor. Or, Ni(CO)4 can be thermally decomposed but reacted with sulfuric acid to generate NiSO4 product.

10. The method for extracting nickel and cobalt from ternary electrode powder according to claim 1, characterized in that, Specifically, step S7 involves further processing the (Na[Co(CO)4]) solution obtained from alkaline absorption in step S5 to prepare cobalt products. The subsequent processing technology is thermal oxidation decomposition to prepare Co2O3 / Co3O4, acidification precipitation to prepare Co(OH)2 / CoCO3, or direct preparation of CoSO4 products. Among them, the thermal oxidation decomposition to prepare Co2O3 / Co3O4 involves heating the absorbent to 80-120℃ and introducing air or oxygen to oxidize and decompose sodium cobalt carbonyl into Co3O4 precipitate, while releasing CO and CO2. After filtration, washing and drying, the Co3O4 precipitate is reduced to metallic cobalt powder by hydrogen at 400-600℃, or directly used as a cobalt oxide product. In the process of preparing Co(OH)2 / CoCO3 by acid precipitation, acid is added to the absorption liquid to adjust the pH to 8-9, so that cobalt precipitates in the form of Co(OH)2 or CoCO3. After filtration and washing, cobalt salt products are obtained, or it can be directly reacted with sulfuric acid to generate CoSO4 solution, and then CoSO4•7H2O products are obtained by evaporation and crystallization. One method involves directly preparing CoSO4 by reacting the absorbent with sulfuric acid to convert sodium cobalt carbonyl into CoSO4, while releasing CO and H2. After purification, evaporation, and crystallization, battery-grade CoSO4 is obtained. Step S8 includes: Cobalt recovery: Uncarbonylated cobalt in the residue is recovered by acid leaching. The leaching is carried out with sulfuric acid, with a liquid-to-solid ratio of 3:1 to 5:1, a temperature of 70 to 85°C, a time of 1 to 2 hours, and a pH of 1.5 to 2.

5. Cobalt and manganese enter the leaching solution, and impurities are separated by precipitation through pH adjustment. Cobalt and manganese are separated by extraction from the leaching solution. CoSO4 or Co(OH)2 products are prepared from the cobalt solution, and MnSO4 products are prepared from the manganese solution. Iron recovery: The metallic iron in the acid leaching residue after the recovery of residual cobalt is separated by magnetic separation or recovered as FeSO4 by acid leaching; Lithium recovery: The reduction residue obtained in step S2 is slurried with water and pressurized with CO2, wherein the pressure is 0.5-2 MPa and the temperature is 20-60℃. Li2CO3 is converted into soluble LiHCO3. After solid-liquid separation, the leachate is heated and decomposed to recover Li2CO3 product. The CO2 comes from the reduction tail gas recovered in step S3 to realize internal CO2 circulation. The heating decomposition temperature is 60-90℃. Manganese recovery: Manganese exists in the form of MnO. In the residual cobalt recovery process, it enters the leaching solution together with cobalt. After extraction and separation, it is used to prepare MnSO4 or MnCO3 products.

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