A method for recovering nickel and cobalt.

Abstract

This application provides a method for recovering nickel and cobalt elements, which involves acid leaching a mixed slurry comprising laterite nickel ore and a hard material to separate a solution containing nickel and cobalt elements; wherein the hard material comprises quartz sand and / or mullite. This recovery method utilizes the high hardness of the hard material to achieve online cleaning of scale layers inside the reactor, thus avoiding contamination of the acid leaching system and solving the problem of scale accumulation inside the reactor, thereby effectively improving the production efficiency of nickel and cobalt metals.

Description

Technical Field

[0001] This application relates to the chemical industry, and in particular to a method for recovering nickel and cobalt. Background Technology

[0002] Laterite nickel ore is an important source of nickel and cobalt resources. Its high-pressure acid leaching process selectively leaches valuable metals such as nickel and cobalt by reacting an acidic solution with the ore under high temperature and pressure. The core equipment of this process is a high-pressure autoclave, which must withstand a high-temperature and high-pressure environment. During this process, impurities such as iron, aluminum, and silicon in the ore easily react with the acidic solution to form scale substances such as hematite (Fe2O3) and bauxite (Al(OH)3). These scale substances adhere to the inner wall of the autoclave, the inner wall of the discharge pipe, and the surface of the agitator blades, forming a hard scale layer.

[0003] However, scaling problems can significantly reduce the heat transfer efficiency of the pressure vessel, hinder material flow, and cause wear on the agitator blades, ultimately forcing the equipment to be shut down frequently for cleaning, which seriously restricts production continuity and the improvement of factory capacity. Summary of the Invention

[0004] This application provides a method for recovering nickel and cobalt elements. By subjecting a mixed slurry comprising laterite nickel ore and hard materials to an acid leaching reaction, the problem of scale accumulation in the reactor is solved, thereby effectively improving the production efficiency of nickel and cobalt metal.

[0005] This application provides a method for recovering nickel and cobalt elements, which involves subjecting a mixed slurry comprising laterite nickel ore and hard materials to an acid leaching reaction to separate a solution containing nickel and cobalt elements; wherein the hard materials comprise quartz sand and / or mullite.

[0006] In the recycling method described above, the hard material has a mass fraction of 2% to 15% in the mixed slurry; and / or, the mixed slurry further includes water, the water having a mass fraction of 55% to 75% in the mixed slurry.

[0007] In the recycling method described above, the D80 of the quartz sand is 75μm~100μm; and / or, the D80 of the mullite is 60μm~120μm.

[0008] In the recycling method described above, the hard material includes a first hard material with a D80 of 80~120μm and a second hard material with a D80 of 50~75μm.

[0009] In the recovery method described above, the D80 of the laterite nickel ore is 300μm~350μm.

[0010] In the recycling method described above, the ratio of the D80 of the hard material to the D80 of the laterite nickel ore is (1:2) to (1:5).

[0011] In the recycling method described above, the mixed slurry is obtained by stirring a mixture comprising laterite nickel ore and hard materials at a stirring speed of 50 rpm to 80 rpm.

[0012] The recycling method described above includes, in which the acid leaching reaction comprises, mixing and reacting the mixed slurry with an acidic medium at 180°C to 250°C and 3 MPa to 6 MPa.

[0013] In the recovery method described above, the acidic medium includes at least one of hydrochloric acid, sulfuric acid, and nitric acid.

[0014] In the recovery method described above, the mass ratio of the laterite nickel ore to the acidic medium is 5:(1~2.25).

[0015] The nickel-cobalt element recovery method provided in this application adds quartz sand and / or mullite with high hardness as hard materials to the slurry including laterite nickel ore and causes it to undergo an acid leaching reaction, thereby achieving online cleaning of the scale layer inside the reactor. This method does not contaminate the acid leaching system and effectively solves the problem of scale accumulation inside the reactor, thereby improving the production efficiency of nickel-cobalt metal. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0017] During acid leaching, nickel and cobalt in laterite nickel ore selectively remain in the solution, allowing them to be separated from other elements. However, other impurities such as iron, aluminum, and silicon tend to form hard scale layers during the acid leaching process, adhering to the inner wall of the reactor. This severely affects the material reaction and causes irreversible wear on the equipment. Therefore, regular equipment cleaning is necessary to remove the accumulated scale, significantly limiting the production efficiency of nickel and cobalt metals.

[0018] The inventors analyzed this phenomenon and concluded that the scaling was caused by insufficient scouring force during the acid leaching process, leading to the deposition of precipitated solids on the reactor wall. Therefore, the inventors attempted to add a high-hardness component to the slurry in order to achieve dynamic removal of the scale.

[0019] Quartz sand's main component is silicon dioxide, which has a Mohs hardness of 7, classifying it as a high-hardness material. It is also acidic, making it compatible with acid leaching systems. Furthermore, silicon dioxide is also a component of laterite nickel ore. Therefore, when silicon dioxide is chosen as a high-hardness additive, it does not introduce additional impurities into the leaching solution.

[0020] Mullite is a stable silicate mineral (3Al2O3·2SiO2) formed from alumina and silicon dioxide at high temperatures. With a Mohs hardness of 6-7, it is also considered a high-hardness material and possesses excellent high-temperature resistance and chemical corrosion resistance. It can enhance mechanical strength and stability without introducing external impurities. Based on these characteristics, the inventors have focused their research on quartz sand and mullite.

[0021] Based on this, this application provides a method for recovering nickel and cobalt elements, which involves acid leaching a mixed slurry comprising laterite nickel ore and hard materials to separate a solution containing nickel and cobalt elements; wherein the hard materials include quartz sand and / or mullite.

[0022] In detail, during the acid leaching process, the hard material particles undergo physical friction with the scale (mainly composed of hematite and bauxite) on the inner wall of the reactor and the surface of the stirring blades under the action of stirring. The rough surface structure of the hard material peels off the scale through van der Waals forces. At the same time, the acid insoluble properties of the hard material keep it stable in the acidic environment and continue to perform the scraping function.

[0023] Therefore, the nickel-cobalt element recovery method of this application can effectively solve the scaling problem in the acid leaching process through the dynamic removal mechanism of hard materials, realize continuous production, and thus improve the production efficiency of nickel-cobalt metal.

[0024] In one specific embodiment, the mass fraction of the rigid material in the mixed slurry is 2% to 15%. The specific mass fraction of the rigid material in the mixed slurry may be, but is not limited to, 2%, 5%, 7%, 8%, 10%, 13%, 15%, or any combination thereof.

[0025] By controlling the amount of hard material added within the above-mentioned range, the balance between the dynamic cleaning mechanism and the slurry flowability can be further ensured. Specifically, when the mass fraction of hard material in the mixed slurry is greater than or equal to 2%, the mixed slurry has high scraping strength; when the mass fraction of hard material in the mixed slurry is less than or equal to 15%, it can also effectively avoid problems such as difficult conveying and potential equipment wear caused by excessively high viscosity of the mixed slurry.

[0026] In one specific embodiment, the mixed slurry further includes water, the water having a mass fraction of 55% to 75% in the mixed slurry. The mass fraction of water in the mixed slurry may specifically be, but is not limited to, 55%, 58%, 64%, 68%, 72%, 73%, 75%, or any combination thereof.

[0027] In detail, when the amount of water added is controlled within the above range, the rheological properties of the slurry can be maintained, and the excessive water dilution of the acidic medium concentration can be avoided, thereby further improving the stability of the acid leaching reaction.

[0028] In one specific embodiment, the D80 of the quartz sand is 75 μm to 100 μm. The D80 of the quartz sand may specifically be, but is not limited to, a range of 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 97 μm, 100 μm, or any combination thereof.

[0029] In detail, when the D80 of the silica sand is greater than or equal to 75 μm, the silica sand can provide a high scraping force, thereby effectively removing dense scale layers. When the D80 of the silica sand is less than or equal to 100 μm, it can also prevent silica sand particles from depositing at the bottom of the reactor due to their large particle size, thereby reducing the contact frequency between the silica sand and the equipment surface and reducing wear on the equipment. Therefore, when the D80 of the silica sand is controlled within the above range, a better balance between scraping force and equipment wear can be achieved. Through continuous mechanical impact and surface friction, the attached scale layer is gradually peeled off, and the peeled scale particles are discharged from the reaction system with the slurry flow, thereby avoiding secondary deposition of scale on the equipment surface.

[0030] In one specific implementation, the D80 of mullite is 60 μm to 120 μm. The D80 of mullite may specifically be, but is not limited to, a range of 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, or any combination thereof.

[0031] In detail, when the D80 of mullite is greater than or equal to 60 μm, mullite can provide high scraping force, thereby effectively removing dense scale layers. When the D80 of mullite is less than or equal to 120 μm, it can also prevent mullite particles from depositing at the bottom of the reactor due to their large particle size, thus reducing the contact frequency between mullite and the equipment surface and reducing wear on the equipment. Therefore, when the D80 of mullite is controlled within the above range, a better balance between scraping force and equipment wear can be achieved. Through continuous mechanical impact and surface friction, the attached scale layer is gradually peeled off, and the peeled scale particles are discharged from the reaction system with the slurry flow, thereby avoiding secondary deposition of scale on the equipment surface.

[0032] In one specific embodiment, the hard material includes a first hard material with a D80 of 80-120 μm and a second hard material with a D80 of 50-75 μm. The D80 of the first hard material may specifically be, but is not limited to, a range of 50 μm, 52 μm, 55 μm, 63 μm, 67 μm, 70 μm, 75 μm, or any combination thereof. The D80 of the second hard material may specifically be, but is not limited to, a range of 80 μm, 86 μm, 92 μm, 97 μm, 105 μm, 115 μm, 118 μm, or any combination thereof.

[0033] By introducing a dual-size hard material system, multi-scale removal of scale can be achieved. Specifically, the large-particle-size hard material primarily scrapes away the macroscopic scale layer adhering to the equipment surface; its higher kinetic energy effectively disrupts the structural integrity of the scale layer. The small-particle-size hard material, on the other hand, enhances the penetrating and stripping effect of the scale layer by filling the micropores on the scale surface. The combination of these two materials creates a stable gradation system of particles of different sizes in the slurry, ensuring sufficient scraping strength while avoiding particle stratification caused by excessive particle size differences, thereby further improving scale removal efficiency.

[0034] In one specific embodiment, the D80 of lateritic nickel ore is 300 μm to 350 μm. The D80 of lateritic nickel ore may specifically be, but is not limited to, a range of 300 μm, 312 μm, 325 μm, 337 μm, 340 μm, 346 μm, 350 μm, or any combination thereof.

[0035] Specifically, the selection of this particle size range is based on a comprehensive consideration of the pulverization characteristics and acid leaching kinetics of lateritic nickel ore. More specifically, when the D80 of the lateritic nickel ore is greater than or equal to 300 μm, a relatively mild acid leaching reaction rate can be ensured, effectively avoiding potential localized overheating and excessively rapid scale formation. When the D80 of the lateritic nickel ore is less than or equal to 350 μm, a higher specific surface area can be ensured, which is beneficial for improving the leaching efficiency of nickel and cobalt. Therefore, when the D80 of the lateritic nickel ore meets the above range, both the nickel-cobalt leaching rate and the scale formation rate are further optimized.

[0036] In one specific embodiment, the ratio of the D80 of the hard material to the D80 of the laterite nickel ore is (1:2) to (1:5). The ratio of the D80 of the hard material to the D80 of the laterite nickel ore can be, but is not limited to, 1:1, 1:2, 1:3, 1:4, 1:5, or any combination thereof.

[0037] In detail, when the ratio of the D80 of the hard material to the D80 of the laterite nickel ore is controlled within the above range, it can ensure that the hard material particles have sufficient freedom of movement in the mixed slurry. This avoids the problem of scraping failure due to excessively dense particles, and also prevents the problem of reduced scale removal efficiency due to excessively sparse particles, thereby further improving the scale removal efficiency.

[0038] In one specific embodiment, the mixed slurry is obtained by stirring a mixture comprising laterite nickel ore and hard materials at a stirring speed of 50 rpm to 80 rpm. The stirring speed may specifically be, but is not limited to, 50 rpm, 55 rpm, 60 rpm, 65 rpm, 70 rpm, 75 rpm, 80 rpm, or any combination thereof.

[0039] In detail, stirring is beneficial for controlling the particle size distribution of lateritic nickel ore and hard materials. When the stirring speed is controlled within the above range, it is more conducive to improving the particle size distribution of the mixed slurry, thereby further improving the scale removal efficiency.

[0040] In one specific embodiment, the acid leaching reaction includes: mixing and reacting the mixed slurry with an acidic medium at a temperature of 180°C to 250°C and a pressure of 3 MPa to 6 MPa. The temperature may specifically be, but is not limited to, a range of 180°C, 190°C, 200°C, 220°C, 235°C, 240°C, 250°C, or any combination thereof, and the pressure may specifically be, but is not limited to, a range of 3 MPa, 4 MPa, 5 MPa, 6 MPa, or any combination thereof.

[0041] Acidic media can provide the necessary acidic environment for the acid leaching reaction. The selection of this temperature and pressure range is based on thermodynamic analysis of the nickel-cobalt leaching reaction in laterite nickel ore. Specifically, when the temperature is greater than or equal to 180℃ and the pressure is greater than or equal to 3 MPa, the reaction rate is higher, which is beneficial for shortening the production cycle; when the temperature is less than or equal to 250℃ and the pressure is less than or equal to 6 MPa, the decomposition of the acidic media and equipment corrosion can be effectively avoided. Therefore, when the temperature and pressure of the acid leaching reaction are selected within the above range, the leaching efficiency of nickel and cobalt and production safety are further balanced. Under these conditions, water molecules in the mixed slurry form a supercritical fluid through high temperature and high pressure, thereby enhancing the diffusion capacity of the acidic media. At the same time, hard material particles continuously contact the scale on the equipment surface in turbulent conditions, forming a dynamic cleaning effect.

[0042] In one specific embodiment, the acidic medium includes at least one of hydrochloric acid, sulfuric acid, and nitric acid.

[0043] As mentioned above, an acidic medium can provide the necessary acidic environment for the acid leaching reaction. When the acidic medium is selected as described above, it is beneficial to increase the solubility of nickel and cobalt in water and to reduce the formation of structural components.

[0044] In one specific embodiment, the mass ratio of lateritic nickel ore to acidic medium is 5:(1~2.25). The specific mass ratio of lateritic nickel ore to acidic medium may be, but is not limited to, 5:1, 5:1.25, 5:1.5, 5:1.75, 5:2, 5:2.15, 5:2.25, or any combination thereof.

[0045] When the mixed slurry comes into contact with the acidic medium, the pH of the mixed slurry will change. The pH can be adjusted by changing the amount of acidic medium added. When the mass ratio of laterite nickel ore to acidic medium is within the above range, the risk of equipment corrosion can be effectively reduced, as can the risk of secondary precipitation of some metal elements. Therefore, when the mass ratio of laterite nickel ore to acidic medium is controlled within the above range, the activity of the acidic medium and the scale removal efficiency are better balanced.

[0046] In one specific implementation, magnetic iron oxide particles can also be added to the mixed slurry. By utilizing the Brownian motion and magnetic adsorption of the magnetic particles during the high-pressure acid leaching process, the scale layer can be actively adsorbed and peeled off, while reducing the proportion of hard materials added and lowering the raw material cost.

[0047] In one specific embodiment, polymer microspheres can be added to the mixed slurry. Their elastic impact characteristics are used to apply periodic impact force to the scale layer, thereby achieving dynamic peeling of the scale layer. The elastic impact of the polymer microspheres can reduce mechanical damage to the inner wall of the equipment, while the periodic impact force prevents scale layer regeneration and extends the service life of the equipment.

[0048] In one specific implementation, the surface of the hard material is subjected to micro-nano structuring treatment (such as etching to form sharp-angled protrusions) to increase its contact area and friction coefficient with the scale layer, thereby accelerating the scale layer peeling speed.

[0049] In one specific implementation, the proportion of hard material added is dynamically adjusted according to the reaction process to match the changes in the scale formation rate, avoiding energy waste caused by excessive hard material, while ensuring the continuity of scale removal and improving process stability.

[0050] In one specific embodiment, an ultrasonic dispersion device is introduced into the slurry preparation step. The ultrasonic cavitation effect improves the uniformity of mixing between the hard material and the slurry, reduces the agglomeration of the hard material, makes it more evenly distributed in the slurry, and improves the scale removal efficiency.

[0051] In one specific implementation, the hard material is added in two stages to match the different stages of scale formation. The staged addition can avoid damage to the equipment caused by excessive friction intensity in the initial stage, while ensuring the continuity of scale removal in the later stage of the reaction and extending the equipment life.

[0052] In one specific implementation, acid concentration gradient control is used during the high-pressure acid leaching process. The rate of scale formation is regulated by acidity changes, which inhibits the excessively rapid scaling reaction in the early stage and accelerates the subsequent metal leaching, thereby reducing the amount of scale formed.

[0053] The following detailed description of the nickel-cobalt element recovery method provided in this application is illustrated through specific embodiments.

[0054] Unless otherwise specified, the reagents, materials and instruments used in the following examples are all conventional reagents, materials and instruments in the art, and can be obtained commercially. The reagents involved can also be synthesized by conventional methods in the art.

[0055] Example 1

[0056] The method for recovering nickel and cobalt in this embodiment includes the following steps:

[0057] 1) Laterite nickel ore (D80 of 325 μm) and quartz sand (D80 of 90 μm) were mixed and then stirred in a ball mill at 60 rpm for 2 hours. Water was then added and the mixture was discharged to obtain a slurry. The mass fraction of quartz sand in the slurry was 10%, and the mass fraction of water in the slurry was 60%.

[0058] 2) Add acidic medium (sulfuric acid) to the above mixed slurry, and then transfer it to a high-pressure reactor for acid leaching reaction for 1 h to separate an aqueous solution containing nickel and cobalt elements; wherein, the acid leaching reaction temperature is 250℃, the pressure is 5 MPa, and the mass ratio of laterite nickel ore to acidic medium is 5:1.

[0059] The chemical composition of laterite nickel ore was determined by ICP-MS, as shown in Table 1.

[0060] Table 1

[0061]

[0062] Example 2

[0063] The method for recovering nickel and cobalt in this embodiment includes the following steps:

[0064] 1) Laterite nickel ore (D80 of 300μm) and quartz sand were mixed, and then the mixture was stirred in a ball mill at 60 rpm for 2 hours. Water was then added and the mixture was discharged to obtain a slurry. The quartz sand consisted of first quartz sand with a D80 of 100μm and second quartz sand with a D80 of 75μm. The mass ratio of the first quartz sand to the second quartz sand was 1:5. The mass fraction of quartz sand in the slurry was 15%, and the mass fraction of water in the slurry was 55%.

[0065] 2) Add acidic medium (sulfuric acid) to the above mixed slurry, and then transfer it to a high-pressure reactor for acid leaching reaction for 1 hour to separate an aqueous solution containing nickel and cobalt elements; wherein, the acid leaching reaction temperature is 250℃, the pressure is 5 MPa, and the mass ratio of laterite nickel ore to acidic medium is 5:2.

[0066] Example 3

[0067] The method for recovering nickel and cobalt in this embodiment includes the following steps:

[0068] 1) Laterite nickel ore (D80 of 350 μm) and quartz sand (D80 of 75 μm) were mixed and then stirred in a ball mill at 50 rpm for 2 hours. Water was then added and the mixture was discharged to obtain a slurry. The mass fraction of quartz sand in the slurry was 10%, and the mass fraction of water in the slurry was 60%.

[0069] 2) Add acidic medium (sulfuric acid) to the above mixed slurry, and then transfer it to a high-pressure reactor for acid leaching reaction for 1 hour to separate an aqueous solution containing nickel and cobalt elements; wherein, the acid leaching reaction temperature is 250℃, the pressure is 5 MPa, and the mass ratio of laterite nickel ore to acidic medium is 5:2.25.

[0070] Example 4

[0071] The method for recovering nickel and cobalt in this embodiment includes the following steps:

[0072] 1) Laterite nickel ore (D80 of 340 μm) and quartz sand (D80 of 100 μm) were mixed and then stirred in a ball mill at 80 rpm for 2 hours. Water was then added and the mixture was discharged to obtain a slurry. The mass fraction of quartz sand in the slurry was 10%, and the mass fraction of water in the slurry was 65%.

[0073] 2) Add acidic medium (sulfuric acid) to the above mixed slurry, and then transfer it to a high-pressure reactor for acid leaching reaction for 1 hour to separate an aqueous solution containing nickel and cobalt elements; wherein, the acid leaching reaction temperature is 250℃, the pressure is 5 MPa, and the mass ratio of laterite nickel ore to acidic medium is 5:1.5.

[0074] Example 5

[0075] The method for recovering nickel and cobalt in this embodiment includes the following steps:

[0076] 1) Laterite nickel ore (D80 of 300 μm) and quartz sand (D80 of 80 μm) were mixed and then stirred in a ball mill at 60 rpm for 2 hours. Water was then added and the mixture was discharged to obtain a slurry. The mass fraction of quartz sand in the slurry was 12%, and the mass fraction of water in the slurry was 58%.

[0077] 2) Add acidic medium (sulfuric acid) to the above mixed slurry, and then transfer it to a high-pressure reactor for acid leaching reaction for 1 hour to separate an aqueous solution containing nickel and cobalt elements; wherein, the acid leaching reaction temperature is 250℃, the pressure is 6 MPa, and the mass ratio of laterite nickel ore to acidic medium is 5:1.8.

[0078] Example 6

[0079] The method for recovering nickel and cobalt in this embodiment includes the following steps:

[0080] 1) Laterite nickel ore (D80 of 320 μm) and mullite (D80 of 100 μm) were mixed and then stirred in a ball mill at 60 rpm for 2 hours. Water was then added and the mixture was discharged to obtain a slurry. The mass fraction of mullite in the slurry was 10%, and the mass fraction of water in the slurry was 65%.

[0081] 2) Add acidic medium (sulfuric acid) to the above mixed slurry, and then transfer it to a high-pressure reactor for acid leaching reaction for 1 hour to separate an aqueous solution containing nickel and cobalt elements; wherein, the acid leaching reaction temperature is 250℃, the pressure is 6 MPa, and the mass ratio of laterite nickel ore to acidic medium is 5:1.

[0082] Comparative Example 1

[0083] The method for recovering nickel and cobalt in this embodiment is basically the same as that in Example 1, except that no quartz sand is added during the process.

[0084] Experimental Example 1

[0085] The D80 and scale adhesion of all embodiments and comparative examples of hard materials and laterite nickel ore were measured, and the results are shown in Table 2; among them,

[0086] D80: Measured using a laser particle size analyzer;

[0087] Scale adhesion: After the high-pressure reactor has been running for 20 days, the scale layer was impacted with a high-pressure water gun. After cracking, it was carefully tapped with an aluminum tool to remove the scale sample. The thickness was then measured with a vernier caliper to characterize the scale adhesion.

[0088] Table 2

[0089]

[0090] As shown in Table 2, the nickel and cobalt recovery method of this application can effectively reduce the adhesion of scale during acid leaching, which helps to improve the generation efficiency.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for recovering nickel and cobalt, characterized in that, An acid leaching reaction is carried out on a mixed slurry comprising laterite nickel ore and hard materials to separate a solution containing nickel and cobalt elements; wherein the hard materials include quartz sand and / or mullite.

2. The recycling method according to claim 1, characterized in that, The rigid material has a mass fraction of 2% to 15% in the mixed slurry; and / or, The mixed slurry also includes water, and the water in the mixed slurry has a mass fraction of 55% to 75%.

3. The recycling method according to claim 1 or 2, characterized in that, The quartz sand has a D80 of 75μm to 100μm; and / or, The D80 of the mullite is 60μm~120μm.

4. The recycling method according to any one of claims 1-3, characterized in that, The hard material includes a first hard material with a D80 of 80~120μm and a second hard material with a D80 of 50~75μm.

5. The recycling method according to any one of claims 1-4, characterized in that, The D80 of the laterite nickel ore is 300μm~350μm.

6. The recycling method according to any one of claims 1-5, characterized in that, The ratio of the D80 of the hard material to the D80 of the laterite nickel ore is (1:2) to (1:5).

7. The recycling method according to any one of claims 1-6, characterized in that, The mixed slurry is obtained by stirring a mixture of laterite nickel ore and hard materials at a speed of 50 rpm to 80 rpm.

8. The recycling method according to any one of claims 1-7, characterized in that, The acid leaching reaction includes mixing and reacting the mixed slurry with an acidic medium at 180℃~250℃ and 3Mpa~6Mpa.

9. The recycling method according to claim 8, characterized in that, The acidic medium includes at least one of hydrochloric acid, sulfuric acid, and nitric acid.

10. The recycling method according to claim 8 or 9, characterized in that, The mass ratio of the laterite nickel ore to the acidic medium is 5:(1~2.25).

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