Method for processing high-pressure leaching slurry

Abstract

Provided is a method for processing a high-pressure leaching slurry. The method includes: performing a continuous countercurrent washing treatment (also known as countercurrent decantation, CCD) on the high-pressure leaching slurry to obtain a leaching 5 slurry overflow; performing a pre-neutralization treatment on the leaching slurry overflow using a neutralizer to obtain a pre-neutralized slurry; and performing an iron-aluminum removal treatment on the pre-neutralized slurry to obtain iron-aluminum slag and an iron-aluminum-removed leaching solution. With the method of the present disclosure, the CCD is performed on the high-pressure leaching slurry obtained subsequent to a 10 high-pressure acid leaching treatment of nickel laterite, to separate nickel laterite leaching residue into a leaching slurry underflow. The pre-neutralization treatment is performed on the leaching slurry overflow. In this way, the nickel laterite leaching residue is separated from the pre-neutralized slurry. Therefore, conditions are created for respective resource utilization of tailings obtained from further processing of the nickel laterite leaching residue and the 15 pre-neutralized slurry obtained subsequent to the pre-neutralization treatment. 20 25 20 19 88 19 M ar 2 02 5 1 9 M a r 2 0 2 5 A B S T R A C T 2 0 2 5 2 0 1 9 8 8 1 9 M a r 2 0 2 5 A B S T R A C T 2 0 2 5 2 0 1 9 8 8

Description

FIELD

[0001] The present disclosure relates to the field of hydrometallurgy, and specifically, to a 5 method for processing a high-pressure leaching slurry. BACKGROUND

[0002] As nickel ore resources are continuously depleted, proven reserves of nickel-rich sulfide ore worldwide are decreasing. Therefore, development and utilization of nickel-poor nickel laterite will become increasingly important. Since nickel laterite has low grades, 10 pyrometallurgical or hydrometallurgical processes are required to obtain high-grade nickel intermediate products. The hydrometallurgical processing of the nickel laterite not only yields a metal nickel but also generates a large amount of tailings, leading to increased manufacturing costs for smelting the nickel laterite and difficulties in recovering and processing wastewater and waste slag. Consequently, how to more comprehensively and 15 efficiently utilize nickel laterite resources is one of the research directions in this field. SUMMARY

[0003] In a first aspect of the present disclosure, a method for processing a high-pressure leaching slurry is provided. The method includes: performing a continuous countercurrent washing treatment (also known as countercurrent decantation, CCD) on the high-pressure 20 leaching slurry to obtain a leaching slurry overflow; performing a pre-neutralization treatment on the leaching slurry overflow using a neutralizer to obtain a pre-neutralized slurry; and performing an iron-aluminum removal treatment on the pre-neutralized slurry to obtain iron-aluminum slag and an iron-aluminum-removed leaching solution. 2025201988   19 Mar 2025

[0004] With the method for processing the high-pressure leaching slurry of the present disclosure, the CCD is performed on the high-pressure leaching slurry obtained subsequent to a high-pressure acid leaching treatment of nickel laterite, to separate nickel laterite leaching residue into a leaching slurry underflow. Then, the pre-neutralization treatment is performed 5 on the leaching slurry overflow. In this way, the nickel laterite leaching residue is separated from the pre-neutralized slurry. Therefore, conditions are created for respective resource utilization of tailings obtained from further processing of the nickel laterite leaching residue and the pre-neutralized slurry obtained subsequent to the pre-neutralization treatment.

[0005] In some embodiments, a pH value of the pre-neutralized slurry ranges from 1.0 to 10   3.0. In this way, the pH value of the leaching slurry overflow can be adjusted, and a gypsum precipitate can be generated.

[0006] In some embodiments, the continuous countercurrent washing treatment comprises 3 stages to 8 stages. In this way, the nickel laterite leaching residue can be separated from the high-pressure leaching slurry into the leaching slurry underflow, while reducing a content of 15 valuable metallic ions in the high-pressure leaching slurry.

[0007] In some embodiments, the neutralizer includes at least one of quicklime, calcium carbonate, and calcium hydroxide. In this way, the neutralizer can be used to adjust the pH value of the high-pressure leaching slurry.

[0008] In some embodiments, the method further includes, subsequent to the 20 pre-neutralization treatment on the leaching slurry overflow, performing a thickening treatment on 50% to 95% by mass of the pre-neutralized slurry to obtain a pre-neutralized underflow and a pre-neutralized overflow. In this way, the gypsum precipitate can be separated from the pre-neutralized slurry while concentrating metallic ions in the pre-neutralized slurry. 25

[0009] In some embodiments, the method further includes: mixing the pre-neutralized underflow with the leaching slurry overflow; and performing the iron-aluminum removal treatment on the pre-neutralized overflow. In this way, the gypsum precipitate formed in the pre-neutralized slurry is returned and mixed with the leaching slurry overflow to provide a template for crystal growth of gypsum newly formed in the leaching slurry overflow, which 30   favors obtaining gypsum particles with large particle size, facilitating tailings processing. 2025201988   19 Mar 2025

[0010] In some embodiments, the method further includes performing a tailings neutralization treatment on the iron-aluminum slag using the neutralizer to obtain tailings and a tailings-neutralized overflow. In this way, a pH value adjustment and a thickening of the tailings can be achieved. 5

[0011] In some embodiments, the method further includes performing a pressure filtration treatment on the tailings. In this way, a satisfactory solid-liquid separation of the tailings can be achieved.

[0012] In some embodiments, a pH value of the tailings-neutralized overflow ranges from 6.0 to 9.0. In this way, the pH value of the tailings-neutralized overflow approaches neutrality, 10 meeting environmental requirements for wastewater discharge.

[0013] In some embodiments, a pH value of the iron-aluminum-removed leaching solution ranges from 3.0 to 5.0. In this way, contents of elements iron and aluminum in the iron-aluminum-removed leaching solution can be reduced.

[0014] In some embodiments, the method further includes performing a nickel-cobalt 15 precipitation treatment on the iron-aluminum-removed leaching solution to obtain a nickel-cobalt product. In this way, elements nickel and cobalt in the nickel laterite can be precipitated and collected. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above and / or additional aspects and advantages of the present disclosure will 20 become more apparent and more understandable from the following description of embodiments taken in conjunction with the accompanying drawings.

[0016] FIG. 1 is a schematic flowchart of a method for processing a high-pressure leaching slurry according to an embodiment of the present disclosure.

[0017] FIG. 2 is a schematic flowchart of a method for processing a high-pressure 25 leaching slurry according to another embodiment of the present disclosure. DETAILED DESCRIPTION

[0018] Embodiments of the present disclosure are described in detail below. Examples of 2025201988   19 Mar 2025 the embodiments are illustrated in the accompanying drawings; however, unnecessary detailed descriptions may be omitted. For instance, detailed descriptions of well-known matters and repetitive explanations of identical structures are omitted. This is done to avoid making the following descriptions unnecessarily lengthy and to facilitate understanding by 5 those skilled in the art. Further, the drawings and the following descriptions are provided to ensure that those skilled in the art can fully understand the present disclosure and are not intended to limit the subject matter described in the claims as attached.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present 10 disclosure belongs. Terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the present disclosure. Unless otherwise specified, numerical values of various parameters mentioned herein can be measured using common measurement methods known in the field (for example, they can be measured based on methods according to the embodiments of the present disclosure). 15

[0020] Terms “comprise”, “include” and “have” as well as any variations thereof used in the specification and claims of the present disclosure are open-ended expressions including contents specified herein but not excluding other aspects.

[0021] In the descriptions of the present disclosure, all numbers disclosed herein are approximate values, whether or not words “about” or “approximately” are used. Each 20 numerical value may vary by up to 10% or less, or by a reasonable difference as deemed appropriate by those skilled in the art, such as 1%, 2%, 3%, 4%, or 5%.

[0022] Unless specifically stated, all embodiments and alternative embodiments of the present disclosure can be combined to form new technical solutions.

[0023] Unless specifically stated, all technical features and alternative technical features 25 can be combined to form new technical solutions.

[0024] During a hydrometallurgical processing of nickel laterite, a high-pressure acid leaching (HPAL) process is a commonly used method for extracting metals such as nickel and cobalt from the nickel laterite. Due to an indefinite composition of the nickel laterite, the acid content and metallic ion concentration of a high-pressure leaching slurry fluctuate within a 30 certain range after high-pressure acid leaching treatment. Since the nickel laterite is poor ore, 2025201988   19 Mar 2025 the hydrometallurgical processing results in a large amount of tailings. Methods for handling the tailings include deep-sea disposal, wet tailings stacking, dry tailings stacking, and the like, among which the dry tailings stacking is most widely applied. Prior to dry stacking of the tailings, it is necessary to minimize a moisture content in the tailings, which can reduce a 5 storage space and facilitate further utilization of the tailings. Moreover, the tailings contain large amounts of iron, which has economic value. Therefore, achieving resource utilization of the tailings will be of great significance to the hydrometallurgical processing industry of the nickel laterite.

[0025] In a first aspect of the present disclosure, a method for processing a high-pressure 10 leaching slurry is provided. The method includes: performing a continuous countercurrent washing treatment (also known as countercurrent decantation, CCD) on the high-pressure leaching slurry to obtain a leaching slurry overflow; performing a pre-neutralization treatment on the leaching slurry overflow using a neutralizer to obtain a pre-neutralized slurry; and performing an iron-aluminum removal treatment on the pre-neutralized slurry to obtain 15 iron-aluminum slag and an iron-aluminum-removed leaching solution. With the method for processing the high-pressure leaching slurry of the present disclosure, as illustrated in FIG. 1, the CCD is performed on the high-pressure leaching slurry obtained subsequent to the high-pressure acid leaching treatment of the nickel laterite. Flocculants and other additives are added during the CCD. The CCD is performed on the high-pressure leaching slurry obtained 20 subsequent to a high-pressure acid leaching treatment of nickel laterite, to separate nickel laterite leaching residue into a leaching slurry underflow. Then, the pre-neutralization treatment is performed on the leaching slurry overflow. In this way, the nickel laterite leaching residue is separated from the pre-neutralized slurry. Therefore, conditions are created for respective resource utilization of tailings obtained from further processing of the nickel 25 laterite leaching residue and the pre-neutralized slurry obtained subsequent to the pre-neutralization treatment. In addition, the pre-neutralized slurry obtained subsequent to the pre-neutralization treatment has a higher pH value than the high-pressure leaching slurry, which facilitates the generation of gypsum from calcium ions in the neutralizer and from sulfate in the high-pressure leaching slurry. 30

[0026] In some embodiments, a pH value of the pre-neutralized slurry ranges from 1.0 to 2025201988   19 Mar 2025 3.0. In this way, the pH value of the leaching slurry overflow can be adjusted, and a gypsum precipitate can be generated.

[0027] In some embodiments, the gypsum includes at least one of calcium sulfate, calcium bisulfate, calcium sulfate dihydrate, and calcium sulfate hemihydrate. 5

[0028] In some embodiments, the continuous countercurrent washing treatment comprises 3 stages to 8 stages. In this way, the nickel laterite leaching residue can be separated from the high-pressure leaching slurry into the leaching slurry underflow, while reducing a content of valuable metallic ions in the high-pressure leaching slurry.

[0029] In some embodiments, the neutralizer includes at least one of quicklime, calcium 10 carbonate, and calcium hydroxide. In this way, the neutralizer can adjust the pH value of the high-pressure leaching slurry, and introduce calcium ions to react with sulfate ions introduced by the high-pressure acid leaching treatment to generate gypsum, precipitating the sulfate ions.

[0030] In some embodiments, the iron-aluminum removal treatment may include a first 15 iron-aluminum removal treatment and a second iron-aluminum removal treatment. In this way, staged precipitation of elements iron and aluminum can be achieved to adjust a process of the iron-aluminum removal treatment based on different compositions of iron and aluminum in the nickel laterite.

[0031] In some embodiments, the method further includes, subsequent to the 20 pre-neutralization treatment on the leaching slurry overflow, performing a thickening treatment on 50% to 95% by mass of the pre-neutralized slurry to obtain a pre-neutralized underflow and a pre-neutralized overflow. As illustrated in FIG. 2, subsequent to the pre-neutralization treatment performed on the leaching slurry overflow, a pH value of the leaching slurry overflow increases, and the calcium ions in the neutralizer react with the 25 sulfate ions in the leaching slurry overflow to form the gypsum, which is then precipitated. Through the thickening treatment, the generated gypsum can be separated and concentrated in the pre-neutralized underflow, while the metallic ions in the pre-neutralized slurry are concentrated in the pre-neutralized overflow.

[0032] In some embodiments, the iron-aluminum removal treatment is performed on 5% 30 to 50% by mass of the pre-neutralized slurry. 2025201988   19 Mar 2025

[0033] In some embodiments, the method further includes: mixing the pre-neutralized underflow with the leaching slurry overflow; and performing the iron-aluminum removal treatment on the pre-neutralized overflow.

[0034] Subsequent to the pre-neutralization treatment performed on the leaching slurry 5 overflow separately, the pre-neutralized underflow is returned to mix with the leaching slurry overflow that is still undergoing the pre-neutralization treatment to complete an underflow cycling. Calcium sulfate in the leaching solution can use gypsum crystals brought by the pre-neutralized underflow as templates and continue to grow on the surfaces of the gypsum crystals, enabling an increased particle size of the gypsum crystals, and gypsum crystals 10 having the particle size greater than or equal to 20 qm are obtained. In addition, subsequent to the CCD performed on the high-pressure leaching slurry, concentrations of metallic ions and acid in the high-pressure leaching slurry subjected to the CCD are obviously reduced compared with the original high-pressure leaching slurry. Such a relatively neutral environment also favors a formation and growth of gypsum particles. The large particle size 15 of the gypsum particles is conducive to improving properties of the tailings, enhances a pressure filtration efficiency of the tailings, and reduces a moisture content of the tailings, thus increasing a stacking efficiency of the tailings.

[0035] In some embodiments, the method further includes performing a tailings neutralization treatment on the iron-aluminum slag using the neutralizer to obtain tailings and 20 a tailings-neutralized overflow.

[0036] During the iron-aluminum removal treatment, by adding the neutralizer, a pH value range for precipitating iron ions and aluminum ions is reached. Subsequent to a completion of the iron-aluminum removal treatment, a pH value of the obtained iron-aluminum-removed leaching solution ranges from 3.0 to 5.0, and the obtained 25 iron-aluminum slag has a certain moisture content and is acidic. Directly piling up or backfilling the iron-aluminum slag in this condition would cause corrosion and pollution to the environment and facilities. Therefore, a pH value of the iron-aluminum slag needs to be further adjusted, and moisture needs to be separated from the iron-aluminum slag to obtain the tailings and the tailings-neutralized overflow. The tailings-neutralized overflow has a pH 30 value close to neutrality and can be discharged or purified, and the tailings can be further 2025201988   19 Mar 2025 processed or utilized.

[0037] In some embodiments, the leaching slurry underflow obtained after the continuous countercurrent washing treatment can be mixed with the iron-aluminum slag for the tailings neutralization treatment using the neutralizer, to obtain the tailings and the tailings-neutralized 5 overflow. In this way, a pH value of the nickel laterite leaching residue contained in the leaching slurry underflow obtained after the continuous countercurrent washing treatment can be adjusted, and a solid-liquid separation can be performed to obtain the tailings and the tailings-neutralized overflow. In some embodiments, the method further includes performing a pressure filtration treatment on the tailings. 10

[0038] Returning the pre-neutralized underflow to the leaching slurry overflow enables the gypsum crystals in the tailings to have a large particle size. Due to having a great volume and a large mass, the particles with a large particle size settle fast and are more likely to be retained by a filtering medium, which improves a filtration efficiency. Therefore, under same conditions of the pressure filtration treatment, a duration of the pressure filtration treatment on 15 the tailings is shortened, achieving a satisfactory solid-liquid separation result. Considering that the tailings obtained subsequent to the solid-liquid separation performed on solids in the iron-aluminum slag still contain a certain amount of water, performing the pressure filtration treatment on the tailings can further reduce the moisture content of the tailings. Tailings containing less moisture are easier to be stored or backfilled and require a smaller space, 20 which helps to lower handling costs or storage costs, and thus enhances overall economic benefits of the method for processing the high-pressure leaching slurry.

[0039] In some embodiments, a feed pressure for the pressure filtration treatment is 6 bar to 7 bar, and a compression pressure for the pressure filtration treatment is 7 bar to 8 bar.

[0040] In some embodiments, a pH value of the tailings-neutralized overflow ranges from 25   6.0 to 9.0. In this way, the pH value of the tailings-neutralized overflow approaches neutrality. When treated as a waste liquid, the tailings-neutralized overflow has low corrosivity, comprehensively mitigating the impact of nickel laterite smelting on the environment.

[0041] In some embodiments, a pH value of the iron-aluminum-removed leaching solution ranges from 3.0 to 5.0. In this way, the elements iron and aluminum in the 30 iron-aluminum-removed leaching solution are fully precipitated. Through the subsequent 2025201988   19 Mar 2025 solid-liquid separation, the elements iron and aluminum can be separated from the iron-aluminum-removed leaching solution containing the elements nickel and cobalt, allowing for obtaining a nickel-cobalt product through a nickel-cobalt precipitation treatment.

[0042] In some embodiments, the method further includes performing a nickel-cobalt 5 precipitation treatment on the iron-aluminum-removed leaching solution to obtain a nickel-cobalt product. In this way, the elements nickel and cobalt in the nickel laterite can be precipitated to obtain a purer nickel-cobalt product.

[0043] Solutions of the present disclosure are described below through specific examples. It should be noted that the examples described below are only used for illustrating the present 10 disclosure and should not be construed as limiting the scope of the present disclosure. Where specific techniques or conditions are not indicated in the examples, the procedures shall be carried out in accordance with the techniques or conditions described in the literature in the field or in accordance with the product specification. The reagents or instruments used without the indication of the manufacturers are all conventional products that can be 15 purchased commercially.

[0044] Example 1

[0045] For the high-pressure leaching slurry of nickel laterite, six-stage CCD was performed for solid-liquid separation to obtain a leaching slurry overflow and a leaching slurry underflow. 20

[0046] A pre-neutralization treatment was performed on the leaching slurry overflow to obtain a pre-neutralized slurry. The pre-neutralization treatment lasted for 4 hours. The pH value of the pre-neutralized slurry was 1.8.

[0047] A first iron-aluminum removal treatment and a second iron-aluminum removal treatment were performed on the pre-neutralized slurry to obtain an iron-aluminum-removed 25 leaching solution and an iron-aluminum slag. The iron-aluminum removal treatment lasted for 5 hours. The pH value of the iron-aluminum-removed leaching solution was 4.7.

[0048] After solid-liquid separation and washing, the iron-aluminum slag was mixed with the leaching slurry underflow for a tailings neutralization treatment using a neutralizer. The tailings neutralization treatment lasted for 4 hours. The pH value at the reaction endpoint was 30   7.5. After the tailings neutralization treatment, a thickening treatment was performed for 2025201988   19 Mar 2025 solid-liquid separation to obtain tailings. A pressure filtration treatment was performed on the tailings to obtain a tailings cake.

[0049] The cycle time for the pressure filtration treatment performed on the tailings was 14.5 minutes. The moisture content of the obtained tailings cake was 30.5%. 5

[0050] Example 2

[0051] For the high-pressure leaching slurry of nickel laterite, six-stage CCD was performed for solid-liquid separation to obtain a leaching slurry overflow and a leaching slurry underflow.

[0052] A pre-neutralization treatment was performed on the leaching slurry overflow to 10 obtain a pre-neutralized slurry. The pre-neutralization treatment lasted for 3 hours. The pH value of the pre-neutralized slurry was 2.2.

[0053] A first iron-aluminum removal treatment and a second iron-aluminum removal treatment were performed on the pre-neutralized slurry to obtain an iron-aluminum-removed leaching solution and an iron-aluminum slag. The iron-aluminum removal treatment lasted for 15   4 hours. The pH value of the iron-aluminum-removed leaching solution was 4.9.

[0054] After solid-liquid separation and washing, the iron-aluminum slag was mixed with the leaching slurry underflow for a tailings neutralization treatment using a neutralizer. The tailings neutralization treatment lasted for 4 hours. The pH value at the reaction endpoint was 7.6. After the tailings neutralization treatment, a thickening treatment was performed for 20 solid-liquid separation to obtain tailings. A pressure filtration treatment was performed on the tailings to obtain a tailings cake.

[0055] The cycle time for the pressure filtration treatment performed on the tailings was 13.8 minutes. The moisture content of the obtained tailings cake was 29.8%.

[0056] Comparative example 1 25

[0057] For the high-pressure leaching slurry of nickel laterite, a pre-neutralization treatment was performed. The pre-neutralization treatment lasted for 3 hours. The pH value of the pre-neutralized slurry was 2.2. Then, six-stage CCD was performed to obtain a leaching slurry overflow and a leaching slurry underflow.

[0058] A first iron-aluminum removal treatment and a second iron-aluminum removal 30 treatment were performed on the leaching slurry overflow to obtain an 2025201988   19 Mar 2025 iron-aluminum-removed leaching solution and an iron-aluminum slag. The iron-aluminum removal treatment lasted for 4 hours. The pH value of the iron-aluminum-removed leaching solution was 4.9.

[0059] After solid-liquid separation and washing, the iron-aluminum slag was mixed with 5 the leaching slurry underflow for a tailings neutralization treatment using a neutralizer. The tailings neutralization treatment lasted for 4 hours. The pH value at the reaction endpoint was 7.6. After the tailings neutralization treatment, a thickening treatment was performed for solid-liquid separation to obtain tailings. A pressure filtration treatment was performed on the tailings to obtain a tailings cake. 10

[0060] The cycle time for the pressure filtration treatment performed on the tailings was 17.6 minutes. The moisture content of the obtained tailings cake was 34.8%.

[0061] In the description of the present disclosure, the terms “first” and “second” are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. “First feature” 15 and “second feature” may include one or more of these features.

[0062] In the description of the present disclosure, “A and / or B” can include A only, B only, or both A and B, where A and B are examples only and can be any technical feature linked by “and / or” in the present disclosure.

[0063] In the present disclosure, a sequence in which steps are written does not imply a 20 strict sequence of execution and therefore does not impose any limitations on the implementation process. An actual sequence of execution of respective steps should be determined by functions and potential internal logics of the steps. Unless specifically stated otherwise, all steps of the present disclosure can be performed sequentially or randomly. Preferably, all the steps of the present disclosure are performed sequentially. For example, if a 25 method includes steps (a) and (b), it indicates that the method can include the steps (a) and (b) performed sequentially, or the steps (b) and (a) performed sequentially. For example, if the method further includes step (c), it indicates that the step (c) can be integrated into the method in any sequence. For example, the method may include steps (a), (b), and (c), steps (a), (c), and (b), or steps (c), (a), and (b). 30

[0064] It should be noted that the present disclosure is not limited to the above 2025201988   19 Mar 2025 embodiments. The above embodiments are examples only. Embodiments having substantially the same composition as the technical concept and exerting the same functional effect within the scope of the technical solutions of the present disclosure are encompassed in the technical scope of the present disclosure. In addition, without departing from the main idea of the 5 present disclosure, various modifications to the embodiments that can be conceived by those skilled in the art and other methods constructed by combining some elements from the embodiments are also encompassed within the scope of the present disclosure.

Claims

1. A method for processing a high-pressure leaching slurry, the method comprising:performing a continuous countercurrent washing treatment on the high-pressure leaching 5 slurry to obtain a leaching slurry overflow;performing a pre-neutralization treatment on the leaching slurry overflow using a neutralizer to obtain a pre-neutralized slurry; andperforming an iron and aluminum removal treatment on the pre-neutralized slurry to obtain iron-aluminum slag and an iron-aluminum-removed leaching solution.10        2. The method according to claim 1, wherein:a pH value of the pre-neutralized slurry ranges from 1.0 to 3.0; and / orthe continuous countercurrent washing treatment comprises 3 stages to 8 stages.

3. The method according to claim 1, wherein the neutralizer comprises at least one of quicklime, calcium carbonate, and calcium hydroxide.15        4. The method according to claim 1, further comprising:subsequent to the pre-neutralization treatment on the leaching slurry overflow, performing a thickening treatment on 50% to 95% by mass of the pre-neutralized slurry to obtain a pre-neutralized underflow and a pre-neutralized overflow.

5. The method according to claim 4, further comprising:20        mixing the pre-neutralized underflow with the leaching slurry overflow; andperforming the iron-aluminum removal treatment on the pre-neutralized overflow.

6. The method according to any one of claims 1 to 5, further comprising:performing a tailings neutralization treatment on the iron-aluminum slag using the neutralizer to obtain tailings and a tailings-neutralized overflow.25        7. The method according to claim 6, further comprising:performing a pressure filtration treatment on the tailings.

8. The method according to claim 6, wherein a pH value of the tailings-neutralized overflow ranges from 6.0 to 9.0.2025201988   19 Mar 20259. The method according to any one of claims 1 to 5, wherein a pH value of the iron-aluminum-removed leaching solution ranges from 3.0 to 5.0.

10. The method according to any one of claims 1 to 5, further comprising:performing a nickel-cobalt precipitation treatment on the iron-aluminum-removed 5 leaching solution to obtain a nickel-cobalt product.

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