Method for full extraction of de-alumination calcium and magnesium and recovery of nickel from waste hydrogenation catalyst acid leaching solution

Abstract

This application discloses a method for the complete extraction of aluminum-removing calcium and magnesium and recovery of nickel from the acid leaching solution of a spent hydrogenation catalyst, belonging to the field of hydrometallurgical technology. The method includes the following steps: S1: Take the acid leaching solution containing nickel, aluminum, calcium, and magnesium from the spent hydrogenation catalyst, adjust the pH of the acid leaching solution, and perform a first-stage multi-stage countercurrent extraction using a composite organic extraction phase to obtain an aluminum-loaded organic phase and an aluminum-removing raffinate; S2: Adjust the pH of the aluminum-removing raffinate, and perform a second-stage multi-stage countercurrent extraction using a composite organic extraction phase to obtain a calcium- and magnesium-loaded organic phase and a purified nickel sulfate solution; S3: Evaporate and crystallize the purified nickel sulfate solution to obtain the nickel sulfate product; wherein the composite organic extraction phase includes a main extractant, co-extractant A, and co-extractant B. The method of this application has advantages such as high nickel recovery rate, thorough impurity removal, short process flow, and no slag or dust pollution.

Description

Technical Field

[0001] This application relates to the field of hydrometallurgical technology, and in particular to a method for the complete extraction of dealuminized calcium and magnesium and recovery of nickel from acid leaching solutions of spent hydrogenation catalysts. Background Technology

[0002] Waste hydrorefining catalysts are a typical type of hazardous solid waste generated by the petrochemical industry. They are mainly composed of porous alumina supports and supported active metal components such as nickel, molybdenum, vanadium, and cobalt. Nickel, as an important strategic metal for new energy, is a core raw material for manufacturing ternary precursors for power batteries. Therefore, the efficient recovery of nickel from waste catalysts has extremely high economic value and environmental significance. In hydrometallurgical recovery processes, inorganic acids (such as sulfuric acid) are typically used to dissolve the waste catalysts to obtain nickel-containing acid leaching solutions. However, due to the chemical composition of the catalysts themselves, the acid leaching solutions contain impurity ions such as aluminum, calcium, magnesium, and iron. Among them, calcium and magnesium ions have similar chemical properties to nickel, making them difficult to separate deeply. Battery-grade nickel sulfate has extremely stringent requirements for the content of calcium and magnesium impurities, which makes the deep removal of impurities from the acid leaching solution a core technical bottleneck restricting the recovery of high-quality nickel.

[0003] Currently, the main industrial treatment of nickel-containing acid leaching solutions relies on hydrolysis neutralization precipitation, which involves adding lime, lime milk, or sodium carbonate as a neutralizing agent to adjust the pH value, causing aluminum and iron to be removed as hydroxide precipitates. While this method is simple and inexpensive, it has serious drawbacks in actual production: First, the aluminum hydroxide colloid generated by aluminum ion hydrolysis has a very large specific surface area, which encapsulates and adsorbs a large number of nickel ions into the slag phase during precipitation, significantly reducing the direct nickel recovery rate. Second, to control costs, companies often choose inexpensive calcium-based neutralizing agents, which, while removing aluminum, introduce a high concentration of calcium ions into the system, leading to excessive calcium content in subsequent products, making it difficult to meet the requirements for battery-grade materials. Furthermore, the large amount of neutralization slag produced has poor filtration performance and high water content, causing both metal loss and significant environmental pressure. To overcome the drawbacks of precipitation, solvent extraction has gradually been applied to the removal of impurities from nickel solutions. Traditional extraction processes often use di(2-ethylhexyl)phosphoric acid (P2O4) as a single extractant. Although P2O4 exhibits good aluminum removal efficiency at low pH, it presents challenges in treating complex systems such as spent hydrogenation catalysts, including low calcium-nickel separation coefficients, significant nickel loss, and a tendency for third-phase emulsification. In aluminum-containing acidic systems, P2O4 readily forms complex gel-like polymers with aluminum, leading to difficulty in oil-water separation and severe emulsification. Industrially, large amounts of higher alcohols (such as isooctanol) are typically added as modifiers to suppress emulsification. However, this not only reduces the effective loading of the extractant but also increases the water solubility loss of the organic phase and the chemical oxygen demand (COD) load of the wastewater.

[0004] In summary, single extractants or traditional binary systems are no longer sufficient to simultaneously meet the triple requirements of deep aluminum removal, extremely low calcium and magnesium residues, and high nickel recovery rates. Therefore, it is particularly necessary to develop a method that can avoid nickel loss, prevent the introduction of new impurities, and achieve deep impurity removal. Summary of the Invention

[0005] This application provides a method for the complete extraction of aluminum-dealuminated calcium and magnesium and the recovery of nickel from the acid leaching solution of waste hydrogenation catalyst. By constructing a specific ternary / quaternary synergistic extraction system of "main extractant + acidic phosphorus co-extractant + neutral phosphorus co-extractant", and with stepwise pH control, it can achieve deep removal of aluminum, calcium and magnesium and efficient recovery of nickel without neutralization precipitation or the introduction of exogenous calcium impurities. It also effectively avoids the formation of third-phase emulsions, and has a short process flow and no slag or dust pollution.

[0006] This application provides a method for the complete extraction of dealuminized calcium and magnesium and recovery of nickel from the acid leaching solution of a spent hydrogenation catalyst, comprising the following steps: S1: Take the acid leaching solution containing nickel, aluminum, calcium, and magnesium from the spent hydrogenation catalyst, adjust the pH of the acid leaching solution, and perform a first-stage multi-stage countercurrent extraction using a composite organic extraction phase to obtain an aluminum-loaded organic phase and an aluminum-removing raffinate; S2: Adjust the pH of the aluminum-removing raffinate, and perform a second-stage multi-stage countercurrent extraction using a composite organic extraction phase to obtain a calcium- and magnesium-loaded organic phase and a purified nickel sulfate solution; S3: Evaporate and crystallize the purified nickel sulfate solution to obtain the nickel sulfate product; wherein: the composite organic extraction phase includes a main extractant, a co-extractant A, and a co-extractant B.

[0007] In the above technical solution, by constructing a multi-element synergistic extraction system consisting of a main extractant, co-extractant A, and co-extractant B, combined with a two-stage countercurrent extraction process with stepped pH control, selective separation of aluminum, calcium, and magnesium and efficient recovery of nickel can be achieved in the acid leaching solution of waste hydrogenation catalyst. The first stage preferentially extracts aluminum using P204 at a lower pH, while the second stage utilizes the synergistic effect of co-extractant A and P204 for deep extraction of calcium and magnesium at a higher pH. Co-extractant B also acts as a phase modifier to prevent emulsification of the third phase in the high-aluminum system. This full extraction technology completely eliminates the traditional neutralization and precipitation steps, avoiding the adsorption loss of nickel by aluminum hydroxide colloids and the introduction of exogenous calcium ions. The final nickel sulfate solution obtained has calcium and magnesium impurity contents of less than 20 mg / L, meeting the production requirements for battery-grade nickel sulfate.

[0008] In some embodiments, in step S1, the pH of the acid leaching solution is adjusted to 2.0-2.5; and / or, in step S2, the pH of the aluminum removal residue is adjusted to 3.5-4.2.

[0009] In the above technical solution, the pH of the first extraction stage is controlled at 2.0~2.5. Under lower pH conditions, P204 has a strong extraction ability for aluminum but a weak extraction ability for calcium and magnesium, thus preferentially extracting aluminum into the organic phase. The pH of the second extraction stage is controlled at 3.5~4.2. Under higher pH conditions, the synergistic effect of co-extractant A and P204 is used to extract calcium and magnesium into the organic phase, while nickel remains in the aqueous phase due to antagonistic effects, thereby achieving stepwise selective separation of aluminum, calcium, and magnesium. This stepwise pH control strategy avoids mutual interference between aluminum, calcium, and magnesium during the extraction process and ensures that each impurity ion is efficiently removed, laying the foundation for obtaining high-purity nickel sulfate.

[0010] In some embodiments, the primary extractant includes di(2-ethylhexyl)phosphoric acid (P204); and / or, the co-extractant A is selected from at least one of acidic organophosphorus extractants, including at least one of: 2-ethylhexyl phosphate mono-2-ethylhexyl ester (P507), di(2,4,4-trimethylpentyl)phosphonic acid (Cyanex 272), di(2,4,4-trimethylpentyl)dithiophosphonic acid (Cyanex 301), and di(2,4,4-trimethylpentyl)monothiophosphonic acid (Cyanex 302); and / or, the co-extractant B is selected from at least one of neutral organophosphorus extractants, including at least one of: tributyl phosphate (TBP), trioctylphosphine oxide (TOPO), trialkylphosphine oxide (TRPO), dimethylheptyl methylphosphonate (P350), and tributylphosphine oxide (TBPO).

[0011] In the above technical solution, P204 serves as the main extractant, exhibiting excellent extraction selectivity for aluminum under low pH conditions. Co-extractant A forms a synergistic extraction system with P204, significantly amplifying the extraction capacity for calcium and magnesium under higher pH conditions. Simultaneously, it inhibits nickel co-extraction due to its antagonistic effect, achieving efficient separation of calcium, magnesium, and nickel. Co-extractant B not only participates in synergistic extraction to further enhance the extraction selectivity for calcium and magnesium but also acts as a phase modifier in the system, preventing the formation of a third-phase emulsion without the need for additional alcohol modifiers. This multi-element synergistic extraction system, combined with a stepped pH control process, enables deep removal of aluminum, calcium, and magnesium. The final nickel sulfate product contains calcium and magnesium contents below 20 mg / L, meeting the requirements for battery-grade materials.

[0012] In some embodiments, the volume content of each component in the composite organic extract phase is as follows: main extractant: 20%~40%; co-extractant A: 5%~15%; co-extractant B: 5%~10%; preferably, the composite organic extract phase further includes a diluent; the diluent is selected from at least one of sulfonated kerosene, No. 260 solvent oil, n-heptane or isooctane.

[0013] In the above technical solution, by controlling the content of the main extractant, co-extractant A, and co-extractant B, the optimal ratio of the multi-element synergistic extraction system can be achieved. With the help of the diluent, the stability and phase separation effect of the extraction process are effectively guaranteed, which greatly improves the calcium and magnesium extraction rate while controlling the nickel loss rate to below 5%. Finally, the calcium and magnesium impurity content in the nickel sulfate product is less than 20 mg / L.

[0014] In some embodiments, in step S1, the first extraction segment satisfies at least one of the following conditions:

[0015] (1) The equilibrium pH value for extraction is 2~2.5;

[0016] (2) The extraction ratio (O / A) is 1:1~5;

[0017] (3) The number of extraction stages is 4 to 6.

[0018] In the above technical solution, the equilibrium pH value of the first stage of extraction is 2~2.5, which can ensure the preferential extraction ability of P2O4 for aluminum, while inhibiting the co-extraction of calcium and magnesium ions, and achieving efficient separation of aluminum from nickel, calcium and magnesium; the extraction ratio (O / A) is 1:1~5, which can ensure the extraction efficiency while taking into account the utilization rate of organic phase; the number of extraction stages is controlled at 4~6 stages, and the extraction rate of aluminum can reach more than 95% through multi-stage countercurrent extraction, while the loss rate of nickel is less than 5%.

[0019] In some embodiments, in step S1, the aluminum extraction rate is greater than 95% and the nickel loss rate is less than 5%.

[0020] The above technical solution ensures the high purity of the final nickel sulfate product, making it meet the production requirements of battery-grade nickel sulfate.

[0021] In some embodiments, the second extraction stage satisfies at least one of the following conditions:

[0022] (1) The equilibrium pH for extraction is 3.5~4.2;

[0023] (2) The extraction ratio (O / A) is 1:1~5;

[0024] (3) The number of extraction stages is 3 to 5.

[0025] In the above technical solution, the equilibrium pH value of the second stage extraction is controlled at 3.5~4.2, which can optimize the synergistic effect of co-extractant A and P204, achieving efficient extraction of calcium and magnesium while inhibiting co-extraction of nickel; the extraction ratio (O / A) is controlled at 1:1~5, which can maintain a suitable organic phase loading while ensuring the calcium and magnesium extraction rate; the number of extraction stages is controlled at 3~5 stages, and calcium and magnesium can be deeply removed through multi-stage countercurrent extraction, and the calcium and magnesium contents in the final nickel sulfate solution are both less than 20 mg / L.

[0026] In some embodiments, in step S2, the calcium and magnesium contents in the purified nickel sulfate solution are both less than 20 mg / L.

[0027] The above technical solution ensures the high purity of the final nickel sulfate product, making it meet the production requirements of battery-grade nickel sulfate.

[0028] In some embodiments, in steps S1 and S2, the aluminum-loaded organic phase and the calcium-magnesium-loaded organic phase are regenerated by sulfuric acid back-extraction, and the resulting blank organic phase is returned to S1 for recycling; the concentration of sulfuric acid is 1~3 mol / L.

[0029] In the above technical solution, sulfuric acid in this concentration range can effectively back-extract the loaded aluminum, calcium, and magnesium ions to obtain a blank organic phase, that is, an organic phase in which the loaded aluminum, calcium, magnesium, and other metal ions have been removed. Its main components are still P2O4, co-extractant A, co-extractant B, and diluent, which restores its ability to extract metal ions. It can be returned to step S1 for recycling, thereby realizing the reuse of the extractant and reducing reagent consumption and cost.

[0030] In some embodiments, the concentration of nickel ions in the acid leaching solution of the waste hydrogenation catalyst is 10 g / L to 30 g / L, the concentration of aluminum ions is 0.1 g / L to 1.5 g / L, the concentration of calcium ions is 0.1 g / L to 1 g / L, and the concentration of magnesium ions is 0.1 g / L to 1 g / L.

[0031] The above technical solution embodies the characteristics of a complex system dominated by nickel and containing aluminum and calcium and magnesium impurities.

[0032] This application has the following beneficial effects:

[0033] 1. The traditional calcium oxide / sodium carbonate neutralization and precipitation process was abandoned, and the acid leaching solution was treated by a full solvent extraction method. This avoided the physical adsorption and encapsulation of nickel ions by aluminum hydroxide colloidal precipitate, reducing the loss pathways of nickel from the source and significantly improving the direct recovery rate of nickel.

[0034] 2. An innovative composite extraction system of P204 + acidic phosphorus (co-extractant A) + neutral phosphorus (co-extractant B) was constructed. In this system, co-extractants A and B have a synergistic effect with P204, which greatly amplifies the separation coefficients of calcium / nickel and magnesium / nickel in the pH range of 3.5 to 4.2. This enables the deep removal of calcium and magnesium (<20 mg / L) while inhibiting the co-extraction of nickel, thus solving the problem of nickel loss that accompanies calcium removal with traditional P204.

[0035] 3. The neutral phosphorus extractant introduced into the system not only participates in synergistic extraction but also acts as an excellent phase modifier. It effectively destroys the structure of the aluminum extract through solvation, preventing the formation of a third-phase emulsion even under high aluminum concentration conditions, ensuring the continuous and stable operation of the extraction process, and reducing the water solubility loss of the organic phase.

[0036] 4. Since no calcium-based neutralizing agent is used, no exogenous calcium ions are introduced throughout the entire process, and calcium and magnesium in the raw solution are deeply removed. The resulting nickel sulfate solution has high purity and can be directly crystallized to produce battery-grade products without complex purification. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0038] The following are definitions of terms used in this application:

[0039] The equilibrium pH of extraction refers to the pH value of the aqueous phase when the extraction system reaches mass transfer equilibrium during multi-stage countercurrent extraction.

[0040] Extraction ratio (O / A): refers to the volume flow rate or volume ratio of the organic phase to the aqueous phase during the extraction process.

[0041] Extraction stage: refers to the number of times the aqueous phase and organic phase pass through the mixing-clarification unit during countercurrent extraction.

[0042] Blank organic phase: refers to the organic phase obtained after the aluminum-loaded organic phase and the calcium-magnesium-loaded organic phase are back-extracted and regenerated with sulfuric acid. The loaded aluminum, calcium, magnesium and other metal ions have been removed. Its main components are still P2O4, co-extractant A, co-extractant B and diluent, restoring the original composition and extraction capacity of the composite organic extraction phase.

[0043] Full extraction: refers to a technical approach that uses solvent extraction to treat acid leaching solutions without neutralization or precipitation steps, and all impurity metals are separated and removed through extraction.

[0044] Existing technologies for treating acid leaching solutions from spent hydrogenation catalysts have several shortcomings: Firstly, while traditional neutralization precipitation methods are simple to operate, the adsorption of nickel by aluminum hydroxide colloids leads to significant nickel loss, and the use of calcium-based neutralizing agents introduces new calcium impurities, generating large amounts of difficult-to-treat neutralization slag. Secondly, the single P204 extraction process suffers from low calcium-nickel separation coefficients, significant nickel loss, and susceptibility to third-phase emulsification when treating complex high-alumina systems. Industrially, large amounts of higher alcohol modifiers are required, increasing costs and environmental burden. Current technologies struggle to simultaneously meet the triple demands of deep aluminum removal, extremely low calcium and magnesium residues, and high nickel recovery rates.

[0045] To address the aforementioned technical problems, this application proposes a method for the complete extraction of aluminum-removed calcium and magnesium and the recovery of nickel from the acid leaching solution of spent hydrogenation catalysts. By constructing a multi-element synergistic extraction system composed of P2O4, acidic phosphorus co-extractants, and neutral phosphorus co-extractants, combined with a two-stage countercurrent extraction process with stepped pH control, deep removal of aluminum, calcium, and magnesium and efficient recovery of nickel can be achieved. The aluminum extraction rate is greater than 95%, the nickel loss rate is less than 5%, and the final nickel sulfate product has calcium and magnesium impurity content below 20 mg / L, meeting the requirements for battery-grade materials. Specifically, the method for the complete extraction of aluminum-removed calcium and magnesium and the recovery of nickel from the acid leaching solution of spent hydrogenation catalysts includes the following steps:

[0046] S1: Take the acid leaching solution of the waste hydrogenation catalyst containing nickel, aluminum, calcium and magnesium, adjust the pH of the acid leaching solution, and use a composite organic extraction phase to carry out the first stage of multi-stage countercurrent extraction to obtain an aluminum-loaded organic phase and aluminum-removed raffinate.

[0047] Specifically, in some embodiments of this application, the composite organic extraction phase includes a main extractant, a co-extractant A, and a co-extractant B; the main extractant includes di(2-ethylhexyl)phosphoric acid (P204); co-extractant A is selected from at least one of acidic organophosphorus extractants, including: 2-ethylhexyl phosphate mono-2-ethylhexyl ester (P507), bis(2,4,4-trimethylpentyl)phosphonic acid (Cyanex 272), bis(2,4,4-trimethylpentyl)dithiophosphonic acid (Cyanex 301), and bis(2,4,4-trimethylpentyl)monothiophosphonic acid (Cyanex 272). At least one of 302); the co-extractant B is selected from at least one of neutral organophosphorus extractants, including at least one of: tributyl phosphate (TBP), trioctylphosphine oxide (TOPO), trialkylphosphine oxide (TRPO), dimethylheptyl methylphosphonate (P350) and tributylphosphine oxide (TBPO).

[0048] In some embodiments of this application, the volume content of each component in the composite organic extract phase is as follows: main extractant: 20%~40%; co-extractant A: 5%~15%; co-extractant B: 5%~10%; preferably, the composite organic extract phase further includes a diluent; the diluent is selected from at least one of sulfonated kerosene, No. 260 solvent oil, n-heptane or isooctane.

[0049] In this step, before extraction, the pH of the acid leaching solution is adjusted to 2.0~2.5 to preferentially extract aluminum and iron into the organic phase.

[0050] In some embodiments of this application, in order to ensure the preferential extraction capability of P204 for aluminum while suppressing the co-extraction of calcium and magnesium ions and achieving efficient separation of aluminum from nickel, calcium, and magnesium, the equilibrium pH value of the first stage of extraction is 2.0 to 2.5. For example, the equilibrium pH value of the first stage of extraction can be a value within the range of 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, or any two of them.

[0051] In some embodiments of this application, in order to ensure extraction efficiency while taking into account the utilization rate of organic phase, the first extraction ratio (O / A) is 1:1 to 5. For example, the first extraction ratio (O / A) can be a value within the range of 1:1, 1:2, 1:3, 1:4, 1:5 or any two of them.

[0052] In some embodiments of this application, the number of the first extraction stages is controlled to be 4 to 6 stages. For example, the number of the first extraction stages can be 4, 5, or 6 stages. When the number of the first extraction stages meets the above range, the extraction rate of aluminum can reach more than 95%, while the loss rate of nickel is less than 5%.

[0053] In addition, in some embodiments of this application, in order to achieve the reuse of the extractant and reduce reagent consumption and cost, the blank organic phase obtained after the aluminum-supported organic phase is regenerated by sulfuric acid back-extraction is returned to S1 for recycling. The concentration of sulfuric acid is 1~3 mol / L, for example, it can be a value within the range of 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L or any combination thereof.

[0054] S2: Adjust the pH of the aluminum-removing extract and perform a second-stage multi-stage countercurrent extraction using a composite organic extraction phase to obtain a calcium-magnesium-loaded organic phase and a purified nickel sulfate solution.

[0055] In this step, the pH of the aluminum-removed raffinate is adjusted to 3.5-4.2. Calcium and magnesium are extracted into the organic phase using a synergistic effect, while nickel is retained in the aqueous phase, thus achieving a stepwise selective separation of aluminum, calcium, and magnesium.

[0056] In some embodiments of this application, the equilibrium pH value of the second-stage extraction is 3.5 to 4.2, for example, it can be a value within the range of 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, or any two of these ranges. When the equilibrium pH value of the second-stage extraction meets the above range, efficient extraction of calcium and magnesium can be achieved while suppressing the co-extraction of nickel.

[0057] In some embodiments of this application, the second extraction ratio (O / A) is 1:1 to 5, for example, it can be a value within the range of 1:1, 1:2, 1:3, 1:4, 1:5, or any two of these. When the second extraction ratio meets the above range, a suitable organic phase loading can be maintained while ensuring the calcium and magnesium extraction rate.

[0058] In some embodiments of this application, the second extraction stage has 3 to 5 stages, for example, 3, 4, or 5 stages. When the number of the second extraction stages meets the above range, calcium and magnesium can be deeply removed, and the calcium and magnesium content in the final nickel sulfate solution is less than 20 mg / L.

[0059] In addition, in some embodiments of this application, the blank organic phase obtained after back-extraction and regeneration of the calcium-magnesium-loaded organic phase with sulfuric acid is returned to S1 for recycling. The concentration of sulfuric acid is 1~3 mol / L, for example, it can be a value within the range of 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, or any combination thereof.

[0060] S3: Evaporate and crystallize the purified nickel sulfate solution to obtain the nickel sulfate product.

[0061] The present application will be further described in detail below with reference to the embodiments. Unless otherwise specified, the raw materials used in the following embodiments are all from commercially available products, and the devices or equipment used are all purchased from conventional commercial sales channels.

[0062] In the specific embodiments of this application, the acid leaching solution of the waste hydrogenation catalyst used is taken from the same batch of treatment solution, and its main components are analyzed as follows: nickel ion concentration is 20 g / L, aluminum ion concentration is 1.2 g / L, calcium ion concentration is 0.8 g / L, magnesium ion concentration is 0.6 g / L, and the pH of the acid leaching solution is 1.2.

[0063] Example 1

[0064] The method for complete extraction of dealuminated calcium and magnesium and recovery of nickel from spent hydrogenation catalyst acid leaching solution in this embodiment includes the following steps:

[0065] (1) Prepare a composite organic extract phase with the following volume content of each component:

[0066] 30% P204, 10% Cyanex 272, 8% TBP, and the remainder sulfonated kerosene were mixed evenly to obtain a composite organic extract phase, which was then saponified with nickel carbonate.

[0067] (2) Perform the first stage of multi-stage countercurrent extraction:

[0068] The pH of the acid leaching solution was adjusted to 2.2. The acid leaching solution and the composite organic extraction phase were mixed at an extraction ratio (O / A) of 1:3 and subjected to 5 stages of countercurrent extraction to obtain an aluminum-loaded organic phase and aluminum-removed raffinate.

[0069] (3) Perform the second stage of multi-stage countercurrent extraction:

[0070] The pH of the aluminum-removed raffinate was adjusted to 3.8. The aluminum-removed raffinate was mixed with the composite organic extraction phase at a ratio (O / A) of 1:5 and subjected to 5 stages of countercurrent extraction to obtain a calcium-magnesium loaded organic phase and a purified nickel sulfate solution.

[0071] (4) The aluminum-loaded organic phase and the calcium-magnesium-loaded organic phase were back-extracted with 1 mol / L sulfuric acid. The back-extraction ratio O / A was 1:5, and the back-extraction stage was 4. The blank organic phase obtained was returned to the extraction process for recycling.

[0072] (5) Evaporate the purified nickel sulfate solution to crystallize and obtain nickel sulfate product.

[0073] Example 2

[0074] The difference from Example 1 is as follows:

[0075] (1) Composite organic extraction phase: 25% P204, 8% Cyanex 272, 5% TBP, the remainder being sulfonated kerosene.

[0076] Example 3

[0077] The difference from Example 1 is as follows:

[0078] (1) Composite organic extraction phase: 35% P204, 12% Cyanex 272, 10% TBP, the remainder being sulfonated kerosene.

[0079] Example 4

[0080] The difference from Example 1 is as follows:

[0081] (1) Composite organic extraction phase: 30% P204, 10% P507, 8% TOPO, and the remainder is No. 260 solvent oil.

[0082] Example 5

[0083] The difference from Example 1 is as follows:

[0084] (2) Perform the first stage of multi-stage countercurrent extraction: adjust the pH of the acid leaching solution to 2.0;

[0085] (3) Perform the second stage of multi-stage countercurrent extraction: adjust the pH of the aluminum-removed extract to 3.6.

[0086] Example 6

[0087] The difference from Example 1 is as follows:

[0088] (2) Perform the first stage of multi-stage countercurrent extraction: adjust the pH of the acid leaching solution to 2.4;

[0089] (3) Perform the second stage of multi-stage countercurrent extraction: adjust the pH of the aluminum-removed extract to 4.0.

[0090] Comparative Example 1

[0091] The difference from Example 1 is as follows:

[0092] (1) Composite organic extraction phase: 10% Cyanex 272, 8% TBP, and the remainder is sulfonated kerosene.

[0093] Comparative Example 2

[0094] The difference from Example 1 is as follows:

[0095] (1) Composite organic extraction phase: 30% P2O4, 8% TBP, and the remainder is sulfonated kerosene.

[0096] Comparative Example 3

[0097] The difference from Example 1 is as follows:

[0098] (2) Perform the first stage of multi-stage countercurrent extraction: adjust the pH of the acid leaching solution to 3.0;

[0099] (3) Perform the second stage of multi-stage countercurrent extraction: adjust the pH of the aluminum-removed extract to 3.0.

[0100] Comparative Example 4

[0101] The extraction was performed using a single P204 extractant, without any co-extractant, which differs from Example 1 in that:

[0102] (1) Organic extraction phase: P204.

[0103] Test methods

[0104] The concentrations of various metal ions in the aluminum-removed raffinate and purified nickel sulfate solution of each example and comparative example were determined using an inductively coupled plasma spectrometer (Thermo Fisher ICAP6000). The test results are shown in Table 1.

[0105] Table 1 Test results for each embodiment and comparative example

[0106]

[0107] A comparison of Examples 1-4 and Comparative Examples 1-2 shows that the multi-component synergistic extraction system composed of P204, acidic phosphorus co-extractants, and neutral phosphorus co-extractants constructed in this application in Examples 1-4 achieved aluminum extraction rates of over 95%, calcium and magnesium removal rates of over 95%, and nickel loss rates of less than 5%. In contrast, Comparative Example 1, lacking co-extractant A, saw its calcium and magnesium removal rates plummet to 91% and 90%, respectively. Comparative Example 2, lacking co-extractant B, experienced the appearance of a third phase in the first extraction step, making further experiments impossible. This indicates that the synergistic effect of co-extractant A and P204 is crucial for achieving deep calcium and magnesium extraction, while co-extractant B ensures stable process operation through phase modification; both are indispensable.

[0108] A comparison of Examples 1, 5, and 6 with Comparative Example 3 shows that Examples 1, 5, and 6, employing a stepped pH control process, achieved aluminum extraction rates exceeding 95% and calcium and magnesium removal rates exceeding 95%. In contrast, Comparative Example 3, using a non-stepped pH control process, while increasing the aluminum extraction rate to 99.5%, resulted in a nickel loss rate of 5.2% in the first extraction stage, reduced calcium and magnesium removal rates to 31% and 19% respectively, and a nickel loss rate of 6.6%. The resulting nickel sulfate solution contained excessively high levels of calcium and magnesium impurities, rendering it unusable. This demonstrates that stepped pH control, through stepwise extraction, effectively avoids mutual interference among various impurity ions during the extraction process, ensuring highly efficient and selective separation of aluminum, calcium, and magnesium.

[0109] A comparison of Examples 1-6 and Comparative Example 4 shows that Examples 1-6, employing the full extraction technology route of this application, achieved aluminum extraction rates exceeding 95%, nickel loss rates below 5%, and calcium and magnesium contents in the purified nickel sulfate solution below 20 mg / L. In contrast, Comparative Example 4, using single P2O4 extraction, achieved calcium and magnesium removal rates of only 84% and 85%, respectively, with a nickel loss rate as high as 8%, and was prone to severe emulsification. This demonstrates that this application completely abandons the traditional neutralization and precipitation process, employing a full solvent extraction method to treat the acid leaching solution, thereby avoiding nickel adsorption loss and the introduction of exogenous calcium ions at the source, and improving separation selectivity and process stability.

[0110] Through the comparison of the above embodiments and comparative examples, it can be clearly seen that the method of separating aluminum, calcium, and magnesium and recovering nickel from the acid leaching solution of waste hydrogenation catalyst of this application by full extraction, by constructing a multi-element synergistic extraction system composed of P204, acidic phosphorus co-extractant and neutral phosphorus co-extractant, combined with a two-stage countercurrent extraction process with stepped pH control, can achieve efficient and selective separation of aluminum, calcium and magnesium and high-purity recovery of nickel. The final nickel sulfate solution obtained has high purity and can be directly crystallized to produce battery-grade products without complicated purification.

[0111] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for the complete extraction of dealuminated calcium and magnesium and recovery of nickel from spent hydrogenation catalyst acid leaching solution, characterized in that, Includes the following steps: S1: Take the acid leaching solution of the waste hydrogenation catalyst containing nickel, aluminum, calcium and magnesium, adjust the pH of the acid leaching solution to 2.0~2.5, and use a composite organic extraction phase to perform the first stage of multi-stage countercurrent extraction to obtain an aluminum-supported organic phase and aluminum-removed raffinate. S2: Adjust the pH of the aluminum-removing raffinate to 3.5~4.2, and perform a second-stage multi-stage countercurrent extraction using the composite organic extraction phase to obtain a calcium-magnesium-loaded organic phase and a purified nickel sulfate solution; S3: Evaporate and crystallize the purified nickel sulfate solution to obtain the nickel sulfate product; Wherein: the composite organic extraction phase includes a main extractant, co-extractant A, and co-extractant B; The main extractant includes di(2-ethylhexyl)phosphoric acid (P204); The co-extractant A is selected from at least one of acidic organophosphorus extractants, which includes at least one of: 2-ethylhexyl phosphate mono-2-ethylhexyl ester (P507), bis(2,4,4-trimethylpentyl)phosphonic acid (Cyanex 272), bis(2,4,4-trimethylpentyl)dithiophosphonic acid (Cyanex 301), and bis(2,4,4-trimethylpentyl)monothiophosphonic acid (Cyanex 302); The co-extractant B is selected from at least one of neutral organophosphorus extractants, which includes at least one of: tributyl phosphate (TBP), trioctylphosphine oxide (TOPO), trialkylphosphine oxide (TRPO), dimethylheptyl methylphosphonate (P350), and tributylphosphine oxide (TBPO); The volume content of each component in the composite organic extract phase is as follows: Main extractant: 20%~40%; Co-extractant A: 5%~15%; Synergist B: 5%~10%.

2. The method according to claim 1, characterized in that, The composite organic extraction phase also includes a diluent; The diluent is selected from at least one of sulfonated kerosene, No. 260 solvent oil, n-heptane, or isooctane.

3. The method according to claim 1, characterized in that, In step S1, the first stage of multi-stage countercurrent extraction satisfies at least one of the following conditions: (1) The equilibrium pH for extraction is 2.0~2.5; (2) The extraction ratio of O / A is 1:1~5; (3) The number of extraction stages is 4 to 6.

4. The method according to claim 1, characterized in that, In step S1, the extraction rate of aluminum is greater than 95%; the loss rate of nickel is less than 5%.

5. The method according to claim 1, characterized in that, In step S2, the second stage multi-stage countercurrent extraction satisfies at least one of the following conditions: (1) The equilibrium pH for extraction is 3.5~4.2; (2) The extraction ratio of O / A is 1:1~5; (3) The number of extraction stages is 3 to 5.

6. The method according to claim 1, characterized in that, In step S2, the calcium and magnesium contents in the purified nickel sulfate solution are both below 20 mg / L.

7. The method according to claim 1, characterized in that, In steps S1 and S2, the aluminum-supported organic phase and the calcium-magnesium-supported organic phase are respectively regenerated by sulfuric acid back-extraction, and the resulting blank organic phase is returned to S1 for recycling; the concentration of the sulfuric acid is 1~3 mol / L.

8. The method according to claim 1, characterized in that, The concentration of nickel ions in the acid leaching solution of the waste hydrogenation catalyst is 10 g / L to 30 g / L, the concentration of aluminum ions is 0.1 g / L to 1.5 g / L, the concentration of calcium ions is 0.1 g / L to 1 g / L, and the concentration of magnesium ions is 0.1 g / L to 1 g / L.

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