Device and method for treating laterite nickel ore using sulfuric acid method

Abstract

A device and method for treating laterite nickel ore using a sulfuric acid method. The device comprises a horizontal reaction kettle (2), wherein the horizontal reaction kettle (2) comprises: a horizontal reaction kettle body, a first feed port, a first steam inlet, and a first discharge port; and N vertical reaction kettles (3) connected in parallel to the first discharge port, wherein each vertical reaction kettle (3) comprises a vertical reaction kettle body, a second feed port, a second steam inlet, and a second discharge port. The device can achieve continuous acid treatment of laterite nickel ore, and facilitates improving treatment efficiency. The present invention achieves an excellent leaching effect, and the leaching rates of nickel and cobalt reach up to 95 wt%. The resulting leaching solution has low acidity, can effectively reduce the consumption of alkali or oxides required for subsequent neutralization treatment and minimize the generation of neutralization slag, facilitates saving costs and reducing the generation of solid waste residues, and is greener and more environmentally friendly.

Description

An apparatus and method for treating laterite nickel ore using the sulfuric acid process. Technical Field

[0001] This invention relates to an apparatus and method for treating laterite nickel ore using the sulfuric acid process, belonging to the field of hydrometallurgy. Background Technology

[0002] Nickel is an important metal, and laterite nickel ore is an important mineral resource for producing nickel products. Laterite nickel ore resources are surface weathering crust deposits formed by the weathering, leaching, and deposition of sulfide nickel ore bodies. Laterite nickel ore contains 1%-2% nickel and 20%-50% iron.

[0003] Currently, most laterite nickel ores with high nickel and low iron content are smelted using pyrometallurgical methods, such as rotary kiln-electric furnace smelting and sintering-blast furnace smelting. However, most surface laterite nickel ores with low nickel and high iron content are stockpiled. As the resources of laterite nickel ores with high nickel and low iron content decrease, the development and utilization of the large stockpiled surface laterite nickel ores (low nickel and high iron) has been put on the agenda. In this type of surface laterite nickel ores, nickel mainly exists in the form of nickel goethite, and nickel is dispersed in gangue minerals in a homogeneous manner. Pyrometallurgical production for processing this type of laterite nickel ores is costly. Therefore, hydrometallurgical processes are mainly used for processing. Hydrometallurgical processes mainly include reduction roasting ammonia leaching, atmospheric pressure acid leaching, and high pressure acid leaching. Reduction roasting ammonia leaching is a pyrometallurgical-hydrometallurgical process, characterized by high energy consumption and high production costs. Atmospheric pressure acid leaching results in a large amount of iron being leached into the solution, leading to high costs for subsequent iron removal. High-pressure acid leaching includes sulfuric acid, nitric acid, and hydrochloric acid methods. Hydrochloric acid methods suffer from high iron leaching rates and equipment corrosion, while nitric acid methods require high-temperature calcination to decompose nitrates, incurring significant heat costs. Sulfuric acid methods utilize waste heat steam generated during acid production, meeting production needs and resulting in low energy consumption. Therefore, high-pressure sulfuric acid leaching is currently the mainstream hydrometallurgical process for treating lateritic nickel ore (low nickel, high iron). However, when treating high-iron lateritic nickel ore with acid methods, iron slag deposition and scaling can easily occur in the reactor during iron precipitation, affecting normal production operations. Summary of the Invention

[0004] In view of the shortcomings of the prior art, one of the objectives of the present invention is to provide an apparatus for treating laterite nickel ore by sulfuric acid process, so as to realize the continuous production operation of the apparatus; another objective of the present invention is to provide a method for treating laterite nickel ore by sulfuric acid process, so as to realize the continuous processing of laterite nickel ore.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] An apparatus for treating laterite nickel ore using the sulfuric acid process, comprising:

[0007] A horizontal reactor, wherein the horizontal reactor has:

[0008] A horizontal reactor body, wherein a first reaction space is defined within the horizontal reactor body for performing a first acid leaching treatment in the first reaction space and obtaining a first acid leaching slurry;

[0009] The first feed inlet is located on the body of the horizontal reactor and is connected to the first reaction space so as to input raw materials such as slurry and acid into the first reaction space;

[0010] The first steam inlet is located on the body of the horizontal reactor and communicates with the first reaction space, and is used to input steam into the first reaction space;

[0011] The first discharge port is located on the body of the horizontal reactor and communicates with the first reaction space, and is used to discharge the first acid-leaching slurry out of the first reaction space.

[0012] N vertical reactors, wherein the vertical reactors have:

[0013] A vertical reactor body, wherein a second reaction space is defined within the vertical reactor body for performing a second acid leaching treatment in the second reaction space and obtaining a second acid-leached slurry;

[0014] The second feed inlet is located on the body of the vertical reactor and communicates with the second reaction space, and is used to input the first acid-leaching slurry into the second reaction space; each second feed inlet is connected to the first discharge outlet.

[0015] The second steam inlet is located on the body of the vertical reactor and communicates with the second reaction space, and is used to input steam into the second reaction space;

[0016] The second discharge port is located on the body of the vertical reactor and communicates with the second reaction space, and is used to discharge the second acid-leaching slurry into the second reaction space.

[0017] Where N is an integer ≥ 2, preferably 2-4.

[0018] Thus, the laterite nickel ore can first undergo high-pressure acid leaching in a horizontal reactor located upstream. At this stage, the acidity in the reaction system is relatively high, and iron in the liquid phase typically does not hydrolyze and precipitate. After the first acid leaching, the slurry enters a vertical reactor located downstream. During high-pressure acid leaching, a large amount of iron continues to enter the liquid phase. The acid in the slurry is consumed, and the acidity reaches a lower level. At this point, the iron in the liquid phase hydrolyzes and precipitates, and some of the resulting iron slag deposits and forms scale in the vertical reactor. Because this invention uses N vertical reactors connected in parallel to the first discharge port, each reactor can serve as a backup for the others, taking turns for the second acid leaching treatment and cleaning. This allows the entire process to operate continuously and stably for extended periods, improving processing efficiency and annual throughput while ensuring good leaching results. Therefore, this application, through the combination of horizontal and vertical reactors, can achieve continuous production operation of the device while ensuring good leaching results.

[0019] Furthermore, the device also includes:

[0020] A flash evaporation discharge device, connected to each vertical reactor, is used to cool and depressurize the second acid-leaching slurry to obtain a mixed slurry; and

[0021] A solid-liquid separation device, which is connected to the flash discharge device, is used to perform solid-liquid separation on the mixed slurry to obtain leachate and leachate residue.

[0022] Furthermore, the flash discharge device includes at least two flash tanks connected in series; the upstream flash tank is connected to each vertical reactor, and the downstream flash tank is connected to a solid-liquid separation device. This facilitates multi-stage flash cooling and depressurization treatment.

[0023] Furthermore, it also includes a steam conveying pipeline, with a first steam inlet and a second steam inlet connected to the steam conveying pipeline.

[0024] Furthermore, a first valve is provided at the second feed inlet, and the inlet end of each first valve is connected to the first discharge outlet; a second valve is provided at the second discharge outlet, and the outlet end of each second valve is connected to the inlet of the flash discharge device. This facilitates the opening and closing of each vertical reactor for convenient operation or cleaning.

[0025] Furthermore, the volume of the horizontal reactor is greater than that of the vertical reactor. Preferably, the volume of the horizontal reactor is 2-6 times that of the vertical reactor, and more preferably 3-5 times.

[0026] Based on the same inventive concept, the present invention also provides a method for treating laterite nickel ore using the sulfuric acid process, which is carried out using the apparatus described above; comprising the following steps:

[0027] S1. Grind and prepare the laterite nickel ore to be processed to obtain a slurry;

[0028] S2. The slurry is fed into the first reaction space for the first acid leaching treatment, and the first acid-leached slurry is obtained at the first discharge port.

[0029] During the first acid leaching treatment, the initial concentration of sulfuric acid in the reaction system within the first reaction space is controlled at 180-200 g / L, the temperature at 250-260℃, the pressure at 4-5 MPa, and the residence time at 0.8-1.2 h.

[0030] S3

[0031] S3-1. The first acid-leaching slurry is fed into M vertical reactors, and steam is fed into the M vertical reactors to carry out a second acid leaching treatment in the second reaction space of the M vertical reactors to obtain the second acid-leaching slurry.

[0032] S3-2. After the target running time of the M vertical reactors, stop feeding the first acid-leaching slurry into the M vertical reactors, and feed the first acid-leaching slurry into H other vertical reactors. Also, feed steam into the H vertical reactors to perform a second acid leaching treatment in the second reaction space of the H vertical reactors to obtain a second acid-leaching slurry. During the operation of the H vertical reactors, clean the M vertical reactors.

[0033] S3-3. After the target running time of the H vertical reactors, stop feeding the first acid-leaching slurry into the H vertical reactors, and feed the first acid-leaching slurry into M other vertical reactors. Also, feed steam into the M vertical reactors to perform a second acid leaching treatment in the second reaction space of the M vertical reactors to obtain a second acid-leaching slurry. During the operation of the M vertical reactors, clean the H vertical reactors.

[0034] S3-4, Repeat S3-2~S3-3;

[0035] During the second acid leaching treatment, the temperature in the second reaction space of the vertical reactor during operation is controlled at 250-260℃, the pressure at 4-5MPa, and the residence time at 0.2-0.3h.

[0036] M is an integer ≥ 1 and < N; H is an integer ≥ 1 and ≤ (NM);

[0037] S4. After cooling and depressurizing the slurry after the second acid leaching, solid-liquid separation is performed to obtain leachate and leach residue.

[0038] By controlling relevant parameters during the first and second acid leaching processes, iron hydrolysis and scaling in the upstream horizontal reactor can be effectively avoided, ensuring that iron hydrolysis and scaling occur in the downstream vertical reactor, thus guaranteeing good leaching results. Furthermore, iron hydrolysis means that the acidity of the slurry has decreased to a certain level after the first acid leaching, thereby reducing the consumption of alkali or oxides required for subsequent neutralization of the leachate, decreasing the amount of neutralization residue generated, helping to save costs, and reducing the amount of solid waste.

[0039] Furthermore, in S1, after grinding, the proportion of minerals with a particle size ≤200 mesh in the total obtained minerals is ≥90wt%, preferably ≥95wt%;

[0040] Preferably, the iron content in the laterite nickel ore to be treated is ≥20wt%, more preferably 25-60wt%, and even more preferably 30-50wt%; preferably, the nickel content in the laterite nickel ore to be treated is 0.5-1.5wt%, more preferably 0.8-1.3wt%; preferably, the cobalt content in the laterite nickel ore to be treated is 0.05-0.18wt%, more preferably 0.08-0.15wt%.

[0041] Optionally, the laterite nickel ore to be processed contains 0.8-1.3 wt% nickel, 0.08-0.18 wt% cobalt, and 40-50 wt% iron.

[0042] Furthermore, in S2, during the first acid leaching treatment, the initial liquid-to-solid ratio of the reaction system in the first reaction space is controlled to be 1-3 mL:1 g, preferably 1.5-2 mL:1 g.

[0043] In S3, the target time is 30-80 days, preferably 40-70 days.

[0044] Furthermore, during the first acid leaching treatment, the initial concentration of sulfuric acid in the reaction system within the first reaction space is controlled at 185-195 g / L, the temperature at 252-258℃, the pressure at 4.2-4.8 MPa, and the residence time at 0.9-1.1 h; during the second acid leaching treatment, the temperature within the second reaction space of the vertical reactor during operation is controlled at 252-258℃, the pressure at 4.2-4.8 MPa, and the residence time at 0.22-0.28 h.

[0045] Optionally, the temperature and pressure are the same during both the first and second acid leaching treatments.

[0046] Optionally, after S4, it also includes:

[0047] S5. After the leachate undergoes a first neutralization treatment, solid-liquid separation is performed to obtain a primary neutralization residue and a primary neutralization liquid.

[0048] During the first neutralization process, the temperature is controlled at 80-90℃, the neutralization time is 1.5-2.0h, and the reaction endpoint is pH 3-4; the residue from the first neutralization can be sent to downstream processes to recover aluminum and scandium.

[0049] S6. After the primary neutralization liquid undergoes a second neutralization treatment, solid-liquid separation is performed to obtain secondary neutralization residue and secondary neutralization liquid.

[0050] During the second neutralization process, the temperature is controlled at 70-80℃, the neutralization time is 1.5-2.0h, and the reaction endpoint is pH 7-8. The secondary neutralization residue is a nickel-cobalt enrichment and can be sent to subsequent processes for nickel-cobalt recovery. The secondary neutralization liquid can be returned to the first acid leaching process.

[0051] Optionally, neutralization treatment may be performed using magnesium oxide and / or magnesium hydroxide.

[0052] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0053] The apparatus of the present invention enables continuous acid processing of laterite nickel ore, which helps to improve processing efficiency.

[0054] The present invention has a good leaching effect, with nickel and cobalt leaching rates as high as 95 wt% or more.

[0055] This invention can utilize steam produced from pyrite or sulfuric acid production, achieving a balance between steam supply and demand and low energy consumption.

[0056] The leachate obtained by this invention has a low acidity, which can effectively reduce the consumption of alkali or oxides required for subsequent neutralization treatment and reduce the amount of neutralization residue generated, thus helping to save costs and reduce the amount of solid waste generated, making it more green and environmentally friendly. Attached Figure Description

[0057] Figure 1 is a process flow diagram of the sulfuric acid process for treating laterite nickel ore according to the present invention.

[0058] Figure 2 is a simplified structural diagram of an apparatus for treating laterite nickel ore using the sulfuric acid process according to the present invention. Detailed Implementation

[0059] The present invention will be described in detail below with reference to embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other. For ease of description, the words "upper," "lower," "left," and "right" appearing below only indicate that they are consistent with the upper, lower, left, and right directions of the drawings themselves, and do not limit the structure. Example 1

[0060] Referring to Figure 2, the apparatus for treating laterite nickel ore using the sulfuric acid process in this embodiment includes:

[0061] Horizontal reactor 2, wherein the horizontal reactor has:

[0062] A horizontal reactor body, wherein a first reaction space is defined within the horizontal reactor body for performing a first acid leaching treatment in the first reaction space and obtaining a first acid leaching slurry;

[0063] The first feed inlet is located on the body of the horizontal reactor and is connected to the first reaction space;

[0064] The first steam inlet is located on the body of the horizontal reactor and is connected to the first reaction space;

[0065] The first discharge port is located on the body of the horizontal reactor and is connected to the first reaction space;

[0066] Two vertical reactors 3, wherein the vertical reactors have:

[0067] A vertical reactor body, wherein a second reaction space is defined within the vertical reactor body for performing a second acid leaching treatment in the second reaction space and obtaining a second acid-leached slurry;

[0068] The second feed inlet is located on the body of the vertical reactor and communicates with the second reaction space; each second feed inlet is connected in parallel to the first discharge outlet;

[0069] The second steam inlet is located on the body of the vertical reactor and communicates with the second reaction space;

[0070] A second discharge port, which is located on the vertical reactor body and communicates with the second reaction space; and

[0071] A manhole is provided on the vertical reactor body to facilitate the cleaning of sludge and scale inside the vertical reactor body.

[0072] The device further includes:

[0073] A flash evaporation discharge device 4, connected to each vertical reactor 3, is used to cool and depressurize the second acid-leaching slurry to obtain a mixed slurry; and

[0074] A solid-liquid separation device 5, connected to the flash evaporation discharge device 4, is used to separate the mixed slurry into solid and liquid components to obtain leachate and leachate residue. The solid-liquid separation device 5 includes a thickener.

[0075] The flash discharge device 4 includes three flash tanks connected in series; the upstream flash tank is connected to each of the vertical reactors 3, and the downstream flash tank is connected to the solid-liquid separation device 5. Each flash tank has an exhaust port, and a sixth valve 15 is installed at the exhaust port.

[0076] It also includes a steam conveying pipeline 13 and a feed pipe 14, with a first steam inlet and a second steam inlet connected to the steam conveying pipeline 13. A pressure pump 1 is installed on the feed pipe 14. A third valve 7 is installed at the first feed inlet, and the outlet end of the feed pipe 14 is connected to the inlet of the third valve 7. A fourth valve 8 is installed at the first discharge outlet. A seventh valve 9 is installed at the first steam inlet, and an eighth valve 16 is installed at the second steam inlet, with the inlets of the seventh valve 9 and the eighth valve 16 connected to the steam conveying pipeline 13.

[0077] A first valve 10 is provided at the second feed inlet, and the inlet end of each first valve 10 is connected to the outlet end of the fourth valve 8; a second valve 11 is provided at the second discharge outlet, and the outlet end of each second valve 11 is connected to the inlet of the flash discharge device 4; a fifth valve 12 is provided at the inlet of the flash discharge device 4, and the outlet end of each second valve 11 is connected to the inlet end of the fifth valve 12.

[0078] Examples 2-4

[0079] A method for treating laterite nickel ore using sulfuric acid, employing the apparatus described in Example 1, includes the following steps:

[0080] S1. Grind the laterite nickel ore to be processed so that the proportion of minerals with a particle size of ≤200 mesh in the total minerals obtained is ≥90wt%, and then mix it with sulfuric acid solution to prepare a slurry.

[0081] S2. The slurry is fed into the first reaction space for the first acid leaching treatment to obtain the first acid-leached slurry.

[0082] S3

[0083] S3-1. The first acid-leaching slurry is fed into a vertical reactor 3 (referred to as "first vertical reactor"), and steam is fed into the first vertical reactor to carry out a second acid leaching treatment in the second reaction space of the first vertical reactor to obtain the second acid-leaching slurry.

[0084] S3-2. After the first vertical reactor has been running for the target time, stop feeding the first acid-leaching slurry into the first vertical reactor, feed the first acid-leaching slurry into another vertical reactor (referred to as the "second vertical reactor"), and feed steam into the second vertical reactor to perform a second acid leaching treatment in the second reaction space of the second vertical reactor to obtain a second acid-leaching slurry; during the operation of the second vertical reactor, clean the first vertical reactor through the manhole;

[0085] S3-3. After the second vertical reactor has been running for the target time, stop feeding the first acid-leaching slurry into the second vertical reactor, feed the first acid-leaching slurry into the first vertical reactor, and feed steam into the first vertical reactor to perform a second acid leaching treatment in the second reaction space of the first vertical reactor to obtain a second acid-leaching slurry; during the operation of the first vertical reactor, clean the second vertical reactor through the manhole;

[0086] S3-4, Repeat S3-2~S3-3;

[0087] S4. After cooling and depressurizing the slurry following the second acid leaching, solid-liquid separation is performed to obtain leachate and leachate residue. The produced leachate residue is stockpiled.

[0088] S5. Add magnesium oxide to the leachate for primary neutralization, control the temperature at 85℃, neutralization time at 2.0h, and the final pH at 3.5. After the reaction is completed, separate the liquid and solid. The primary neutralization residue is sent to the subsequent process to recover aluminum and scandium, and the primary neutralization solution is sent to the secondary neutralization.

[0089] S6. Add magnesium oxide to the primary neutralization solution for secondary neutralization, control the temperature at 75℃, neutralization time at 1.8h, and the final pH at 8.0. After the reaction is completed, separate the liquid and solid. The secondary neutralization residue is a nickel-cobalt enrichment and is sent to the subsequent process to recover nickel and cobalt. The secondary neutralization solution can be returned to S1.

[0090] Please refer to Table 1 for relevant parameters and leaching results.

[0091] Table 1

[0092]

[0093] Note: The volume of the horizontal reactor for the first acid leaching treatment is 4 × 100 m³. 3 The vertical reactor for the second acid leaching treatment has a volume of 100m³. 3 .

[0094] The results showed that in the above four embodiments, no significant scaling was observed in the horizontal reactor after 220 days of continuous operation; the cleaning cycles for the vertical reactor were 40 days, 45 days, 55 days, and 60 days, respectively.

[0095] It is evident that by employing the apparatus and method of the present invention, high nickel and cobalt leaching rates can be obtained, both reaching over 95 wt%, and each vertical reactor can serve as a backup for the others, enabling continuous operation of the process.

[0096] Comparative Example 1

[0097] Example 1 was repeated, except that during the first acid leaching treatment, the initial concentration of sulfuric acid in the reaction system was controlled to be 210 g / L.

[0098] As a result, the H2SO4 content of the leachate in S4 was 38 g / L, the Fe content was 7.4 g / L, the nickel leaching rate was 96.0%, and the cobalt leaching rate was 95.6%.

[0099] Example 5

[0100] Example 1 was repeated, except that during the first acid leaching treatment, the initial concentration of sulfuric acid in the reaction system was controlled to be 180 g / L.

[0101] As a result, the H2SO4 content of the leachate in S4 was 22 g / L, the Fe content was 2.4 g / L, the leaching rate of nickel was 95.2%, and the leaching rate of cobalt was 95.0%.

[0102] Comparative Example 2

[0103] Example 1 was repeated, except that during the first acid leaching treatment, the initial concentration of sulfuric acid in the reaction system was controlled to be 170 g / L.

[0104] As a result, the leaching rate of nickel was 92.8%, and the leaching rate of cobalt was 92.0%.

[0105] Comparative Example 3

[0106] Example 1 was repeated, except that the volume of the vertical reactor was 60m³ during the second acid leaching treatment. 3 The residence time during the second acid leaching treatment was controlled to be 0.14 h.

[0107] As a result, the Fe content of the leachate in S4 was 5.8 g / L, the leaching rate of nickel was 95.3%, and the leaching rate of cobalt was 95.2%.

[0108] Comparative Example 4

[0109] Example 1 was repeated, except that the volume of the horizontal reactor was 300 m³ during the first acid leaching treatment. 3 The residence time during the first acid leaching treatment was controlled to be 0.72 h.

[0110] As a result, the leaching rate of nickel was 92.5% and the leaching rate of cobalt was 91.0%.

[0111] The above embodiments should be understood as being used only to illustrate the present invention more clearly, and not to limit the scope of the present invention. After reading the present invention, any modifications of the present invention in various equivalent forms by those skilled in the art fall within the scope defined by the appended claims.

Claims

1. An apparatus for treating laterite nickel ore using the sulfuric acid process, characterized in that, include: Horizontal reactor (2), wherein the horizontal reactor has: A horizontal reactor body, wherein a first reaction space is defined within the horizontal reactor body for performing a first acid leaching treatment in the first reaction space and obtaining a first acid leaching slurry; The first feed inlet is located on the body of the horizontal reactor and is connected to the first reaction space; The first steam inlet is located on the body of the horizontal reactor and is connected to the first reaction space; The first discharge port is located on the body of the horizontal reactor and is connected to the first reaction space; N vertical reactors (3), where N is an integer ≥ 2, wherein the vertical reactors have: A vertical reactor body, wherein a second reaction space is defined within the vertical reactor body for performing a second acid leaching treatment in the second reaction space and obtaining a second acid-leached slurry; The second feed inlet is located on the body of the vertical reactor and communicates with the second reaction space; each second feed inlet is connected in parallel to the first discharge outlet; The second steam inlet is located on the body of the vertical reactor and communicates with the second reaction space; The second discharge port is located on the body of the vertical reactor and is connected to the second reaction space.

2. The apparatus for treating laterite nickel ore using the sulfuric acid process according to claim 1, characterized in that, Also includes: Flash discharge device (4), which is connected to each vertical reactor (3), is used to cool and depressurize the second acid-leaching slurry and obtain a mixed slurry; as well as Solid-liquid separation device (5), which is connected to the flash discharge device (4), is used to perform solid-liquid separation on the mixed slurry to obtain leachate and leachate residue.

3. The apparatus for treating laterite nickel ore using the sulfuric acid process according to claim 2, characterized in that, The flash discharge device (4) includes at least two flash tanks connected in series; The flash tank at the uppermost end is connected to each vertical reactor (3), and the flash tank at the lowermost end is connected to the solid-liquid separation device (5).

4. The apparatus for treating laterite nickel ore using the sulfuric acid process according to claim 1, characterized in that, It also includes a steam conveying pipeline (13), with a first steam inlet and a second steam inlet connected to the steam conveying pipeline (13).

5. The apparatus for treating laterite nickel ore using the sulfuric acid process according to claim 1, characterized in that, A first valve (10) is provided at the second feed inlet, and the inlet end of each first valve (10) is connected to the first discharge port; a second valve (11) is provided at the second discharge port, and the outlet end of each second valve (11) is connected to the inlet of the flash discharge device (4).

6. A method for treating laterite nickel ore using sulfuric acid, characterized in that, Performed using the apparatus as described in any one of claims 1-5; comprising the following steps: S1. Grind and prepare the laterite nickel ore to be processed to obtain a slurry; S2. The slurry is fed into the first reaction space for a first acid leaching treatment to obtain a first acid-leached slurry; wherein, during the first acid leaching treatment, the initial concentration of sulfuric acid in the reaction system in the first reaction space is controlled to be 180-200 g / L, the temperature to be 250-260℃, the pressure to be 4-5 MPa, and the residence time to be 0.8-1.2 h. S3, S3-1, The first acid-leached slurry is fed into M vertical reactors (3), and steam is fed into the M vertical reactors to carry out the second acid leaching treatment in the second reaction space of the M vertical reactors to obtain the second acid-leached slurry; S3-2. After the target running time of the M vertical reactors, stop feeding the first acid-leaching slurry into the M vertical reactors, and feed the first acid-leaching slurry into H other vertical reactors. Also, feed steam into the H vertical reactors to perform a second acid leaching treatment in the second reaction space of the H vertical reactors to obtain a second acid-leaching slurry. During the operation of the H vertical reactors, clean the M vertical reactors. S3-3. After the target running time of the H vertical reactors, stop feeding the first acid-leaching slurry into the H vertical reactors, and feed the first acid-leaching slurry into M other vertical reactors. Also, feed steam into the M vertical reactors to perform a second acid leaching treatment in the second reaction space of the M vertical reactors to obtain a second acid-leaching slurry. During the operation of the M vertical reactors, clean the H vertical reactors. S3-4, repeat S3-2~S3-3; wherein, during the second acid leaching treatment, the temperature in the second reaction space of the vertical reactor during operation is controlled at 250-260℃, the pressure at 4-5MPa, and the residence time at 0.2-0.3h; M is an integer ≥1 and <N; H is an integer ≥1 and ≤ (NM); S4. After cooling and depressurizing the slurry after the second acid leaching, solid-liquid separation is performed to obtain leachate and leach residue.

7. The method according to claim 6, characterized in that, In S1, after grinding, the proportion of minerals with a particle size ≤200 mesh in the total obtained minerals is ≥90wt%, preferably ≥95wt%; preferably, the iron content in the laterite nickel ore to be processed is ≥20wt%, preferably 25-60wt%, more preferably 30-50wt%; preferably, the nickel content in the laterite nickel ore to be processed is 0.5-1.5wt%, preferably 0.8-1.3wt%; preferably, the cobalt content in the laterite nickel ore to be processed is 0.05-0.18wt%, preferably 0.08-0.15wt%.

8. The method according to claim 6, characterized in that, In S2, during the first acid leaching treatment, the initial liquid-to-solid ratio of the reaction system in the first reaction space is controlled to be 1-3 mL:1 g, preferably 1.5-2 mL:1 g.

9. The method according to claim 6, characterized in that, In S3, the target time is 30-80 days, preferably 40-70 days.

10. The method according to claim 6, characterized in that, During the first acid leaching treatment, the initial concentration of sulfuric acid in the reaction system within the first reaction space is controlled at 185-195 g / L, the temperature at 252-258℃, the pressure at 4.2-4.8 MPa, and the residence time at 0.9-1.1 h. During the second acid leaching treatment, the temperature within the second reaction space of the vertical reactor during operation is controlled at 252-258℃, the pressure at 4.2-4.8 MPa, and the residence time at 0.22-0.28 h.

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