Method for multi-stage continuous preparation of MHP from laterite-nickel ore

Abstract

The invention discloses a method for multi-stage continuous preparation of MHP from laterite-nickel ore, which comprises the following steps: firstly, carrying out high-pressure acid leaching, iron removal and aluminum removal on the laterite-nickel ore to obtain a nickel precipitation pre-solution, then inputting the nickel precipitation pre-solution into a first-stage reaction tank, adding magnesium oxide powder, inputting the reaction solution into a second-stage reaction tank, adding magnesium oxide powder again, and carrying out secondary reaction; and inputting the reaction liquid into a third-stage reaction tank, adding sodium hydroxide powder, finally treating by a thickener, and carrying out filter pressing by a filter press to obtain the MHP. The three-stage reaction is adopted, the process is continuous, the nickel laterite ore pickle liquor is subjected to the three-stage reaction, precipitation of Ni < 2 + > is facilitated, and the nickel precipitation rate is higher; only a small amount of sodium hydroxide is added as required during the three-stage reaction, and the alkalinity of magnesium oxide is weaker than that of sodium hydroxide, so that the local'over-alkalinity 'phenomenon is not easy to generate in the use process, and the problem of difficult sedimentation and filtration when magnesium hydroxide is used as a precipitator at present is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of hydrometallurgy, and more specifically to a method for continuously preparing MHP from laterite nickel ore in multiple stages. Background Art

[0002] Nickel is an important metal material. It is not only the basic material for manufacturing nickel alloys, but also widely used in electroplating, catalysts, batteries, etc. In recent years, with the rapid development of the new energy industry, the demand for power batteries has increased dramatically, and the demand for nickel, an important raw material for battery materials, has also increased rapidly.

[0003] At present, the main processes for producing nickel are pyrometallurgy and hydrometallurgy. Hydrometallurgy of laterite nickel ore is the main process for preparing nickel. After high-pressure acid leaching of laterite nickel ore, Ni 2+ 、Co 2+ Mg 2+ , Mn 2+ The ore pulp is neutralized, washed, impurity-removed, and then a precipitant is added to obtain the intermediate product MHP.

[0004] In the process of wet nickel extraction from laterite nickel ore, sodium hydroxide is mostly used as a precipitant in the precipitation process. Excessive sodium hydroxide and low-flow nickel precipitation are added to the pre-nickel precipitation liquid as seeds. After a certain period of reaction, a flocculant is added to the thickener for sedimentation. After sedimentation, more than 50% of the low-flow is returned to the precipitation process as seeds, and the remaining low-flow is filtered by a filter press to obtain MHP. Although the process is simple, most of the low-flow after nickel precipitation returns to the precipitation process for repeated circulation, and the nickel precipitation efficiency is low. In addition, sodium hydroxide is used as a precipitant. Due to its strong alkalinity, the generated nickel hydroxide slurry has the problems of difficult sedimentation and filtration, which not only affects the production efficiency, but also leads to a high water content of MHP, and high energy consumption and transportation costs in the later stage. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is to provide a method for multi-stage continuous preparation of MHP from laterite nickel ore with high efficiency, high nickel precipitation rate and cost advantage.

[0006] In order to solve the above technical problems, the present invention provides the following technical solution: a method for multi-stage continuous preparation of MHP from laterite nickel ore, comprising the following steps:

[0007] Step A: subjecting laterite nickel ore to high pressure acid leaching to remove iron and aluminum to obtain a nickel precipitation pre-liquid;

[0008] Step B: feeding the nickel precipitation pre-liquid into the primary reaction tank from the reserved tube, and continuously and intermittently adding magnesium oxide powder into the primary reaction tank through an intermittent parallel feeder;

[0009] Step C: the reaction liquid in the primary reaction tank overflows into the secondary reaction tank through the first overflow pipe, and at the same time, the intermittent parallel feeder continuously and intermittently adds magnesium oxide powder into the secondary reaction tank;

[0010] Step D: The reaction liquid in the secondary reaction tank overflows into the tertiary reaction tank through the second overflow pipe, and at the same time, the intermittent parallel feeder continuously and intermittently adds sodium hydroxide powder into the tertiary reaction tank;

[0011] Step E: the reaction liquid in the tertiary reaction tank overflows into the thickener through the third overflow pipe;

[0012] Step F: The liquid treated by the thickener is input into a buffer tank, and the buffer tank supplies the liquid into a filter press, and MHP is obtained after filtration by the filter press.

[0013] The above-mentioned method for preparing MHP from laterite nickel ore in multiple stages continuously comprises the following steps: in step A, Ni in the nickel precipitation pre-liquid is 2+ The content is 0.5~10g / L.

[0014] In the above-mentioned method for multi-stage continuous preparation of MHP from laterite nickel ore, the total residence time of the nickel precipitation pre-liquid in the primary reaction tank, the secondary reaction tank and the tertiary reaction tank is 3 to 9 hours, preferably 5 to 7 hours.

[0015] In the above-mentioned method for multi-stage continuous preparation of MHP from laterite nickel ore, the mass ratio of magnesium oxide powder added to the primary reaction tank, magnesium oxide powder added to the secondary reaction tank, and sodium hydroxide powder added to the tertiary reaction tank is 7-9:2-0.5:1-0.5.

[0016] In the above-mentioned method for multi-stage continuous preparation of MHP from laterite nickel ore, the difference in liquid level between the primary reaction tank and the secondary reaction tank is ≥10 cm, and the difference in liquid level between the secondary reaction tank and the tertiary reaction tank is ≥10 cm; the inlet end of the first overflow pipe is inserted into the primary reaction tank and extends toward the bottom of the tank, and the outlet end of the first overflow pipe is located on the top of the secondary reaction tank; the inlet end of the second overflow pipe is inserted into the secondary reaction tank and extends toward the bottom of the tank, and the outlet end of the second overflow pipe is located on the top of the tertiary reaction tank; the inlet end of the third overflow pipe is inserted into the tertiary reaction tank and extends toward the bottom of the tertiary reaction tank, the outlet end of the third overflow pipe is in fluid communication with the thickener, and a delivery pump is installed on the third overflow pipe.

[0017] In the above-mentioned method for multi-stage continuous preparation of MHP from laterite nickel ore, the primary reaction tank, the secondary reaction tank and the tertiary reaction tank are all equipped with stirring motors through support frames, and stirring blades are coaxially fixedly connected to the power output shaft of the stirring motor.

[0018] The above-mentioned method for multi-stage continuous preparation of MHP from laterite nickel ore, the intermittent parallel feeder includes a frame, a drive assembly, a first feeding assembly, a second feeding assembly and a third feeding assembly, the frame is installed above the primary reaction tank, the drive assembly is installed in the middle position of the frame, the first feeding assembly, the second feeding assembly and the third feeding assembly are respectively installed on the frame along the circumferential direction of the drive assembly, the drive assembly drives the first feeding assembly, the second feeding assembly and the third feeding assembly to open when the circumference rotates, the first feeding assembly, the second feeding assembly and the third feeding assembly are respectively connected to different powder storage tanks through feeding pipes, and the first feeding assembly, the second feeding assembly and the third feeding assembly are respectively connected to the primary reaction tank, the secondary reaction tank and the tertiary reaction tank through distribution pipes.

[0019] In the above-mentioned method for multi-stage continuous preparation of MHP from laterite nickel ore, the first feeding assembly, the second feeding assembly and the third feeding assembly have the same structure; the first feeding assembly includes a metering cylinder, a first baffle, a second baffle, a main rotating shaft, a secondary rotating shaft and a linkage arm, a mounting hole is provided on the frame, an elastic sleeve is provided in the mounting hole, the metering cylinder is installed in the elastic sleeve, the first baffle is slidably fitted on the top end of the metering cylinder, the second baffle is slidably fitted on the bottom end of the metering cylinder, a first through hole matching the inner diameter of the metering cylinder is provided on the first baffle, a second through hole matching the inner diameter of the metering cylinder is provided on the second baffle, the positions of the first through hole and the second through hole are staggered, and the main rotating shaft is rotatably fitted on the frame The first end of the second torsion spring is fixedly connected to the main rotating shaft and is parallel to the measuring cylinder, the first end of the main rotating shaft is fixedly connected to the first baffle through the first swing arm, the secondary rotating shaft coaxially rotates and fits in the second end of the main rotating shaft, the end of the secondary rotating shaft is fixedly connected to the second baffle through the second swing arm, one end of the linkage arm is fixedly connected to the main rotating shaft, and the other end of the linkage arm extends toward the direction of the driving assembly and is drivingly connected to the driving assembly, the main rotating shaft is provided with a first torsion spring, one end of the first torsion spring is fixedly connected to the main rotating shaft, and the other end of the first torsion spring is fixedly connected to the frame, and a second torsion spring is installed on the secondary rotating shaft, one end of the second torsion spring is fixedly connected to the main rotating shaft, and the other end of the second torsion spring is fixedly connected to the secondary rotating shaft.

[0020] In the above-mentioned method for multi-stage continuous preparation of MHP from laterite nickel ore, the driving assembly comprises a driving motor, a driving column and a turntable, the driving motor is fixedly mounted on the frame, the driving column is coaxially fixedly connected to the output shaft of the driving motor, and the turntable is coaxially fixed to the end of the driving column;

[0021] The driving column is located between the first feeding component, the second feeding component and the third feeding component. Three driving arms are installed on the outer circumferential surface of the driving column. The axial positions of the three driving arms on the driving column are staggered with each other. The linkage arm of the first feeding component, the linkage arm of the second feeding component and the linkage arm of the third feeding component respectively correspond to the axial position of one of the driving arms. The linkage arm rotates to drive the first swing arm to swing around the main rotation axis.

[0022] A limiting block is coaxially fixedly connected to the end of the secondary rotating shaft, a limiting groove is opened on the surface of the turntable in the circumferential direction, and three release grooves with a width greater than the limiting groove are opened in the circumferential direction of the limiting groove. The limiting groove and the release groove are connected, and the limiting block is inserted and slidably fitted in the limiting groove.

[0023] The technical solution of the present invention achieves the following beneficial technical effects:

[0024] 1. The present invention adopts a three-stage reaction, and the process is continuous. After the laterite nickel ore acid leaching solution undergoes the three-stage reaction, it is beneficial for Ni 2+ The nickel precipitation rate is higher and it is easy to control. The nickel hydroxide precipitate is easy to settle and filter, which can reduce production costs and significantly improve production efficiency. In the primary and secondary nickel precipitation processes, magnesium oxide is used as a precipitant, and only a small amount of sodium hydroxide is added as needed during the tertiary reaction. The alkalinity of magnesium oxide is weaker than that of sodium hydroxide, and it is not easy to produce local "over-alkalinity" during use, avoiding the current sedimentation and filtration difficulties when using magnesium hydroxide as a precipitant. In the primary and secondary reaction processes, the introduction of magnesium oxide precipitant greatly reduces the unit consumption and the precipitant cost is also lower.

[0025] 2. The present invention provides an intermittent parallel feeder, which can add different powders to the primary reaction tank, the secondary reaction tank and the tertiary reaction tank respectively, thereby realizing accurate control of the feeding amount and the feeding time interval. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the process flow of multi-stage continuous preparation of MHP from laterite nickel ore of the present invention;

[0027] Figure 2 A schematic cross-sectional view of a process flow diagram of a multi-stage continuous preparation process of MHP from laterite nickel ore according to the present invention;

[0028] Figure 3 A schematic diagram of the top view of the intermittent parallel feeder of the present invention;

[0029] Figure 4 A partial front view structural schematic diagram of the intermittent parallel feeder of the present invention;

[0030] Figure 5A partial front view stereoscopic structural schematic diagram of the intermittent parallel feeder of the present invention;

[0031] Figure 6 A schematic diagram of a partial side cross-sectional structure of the intermittent parallel feeder of the present invention;

[0032] Figure 7 A schematic diagram of the top view of the rotating disk in the intermittent parallel feeder of the present invention.

[0033] The reference numerals in the figure are as follows: 1-primary reaction tank; 2-secondary reaction tank; 3-tertiary reaction tank; 4-intermittent parallel feeder; 41-frame; 42-driving assembly; 421-driving motor; 422-driving column; 423-turntable; 424-driving arm; 425-restriction slot; 426-release slot; 43-first feeding assembly; 431-quantitative cylinder; 432-first baffle; 433-first through hole; 434-second baffle; 435-second through hole; 436-impact plate; 437- Main rotating shaft; 438-first swing arm; 439-first torsion spring; 440-linkage arm; 441-second rotating shaft; 442-second torsion spring; 443-limiting block; 444-second swing arm; 44-second feeding assembly; 45-third feeding assembly; 5-first overflow pipe; 6-second overflow pipe; 7-third overflow pipe; 8-thickener; 9-buffer tank; 10-filter press; 11-reserved pipe; 12-agitation motor; 13-agitation blade; 14-feed pipe; 15-distribution pipe; 16-elastic sleeve. DETAILED DESCRIPTION

[0034] A method for preparing MHP from laterite nickel ore in multiple stages in this embodiment is as follows: Figure 1-2 , including the following steps:

[0035] Step A: The laterite nickel ore is subjected to high pressure acid leaching to remove iron and aluminum to obtain a nickel precipitation pre-liquid. 2+ The content is 3.55g / L;

[0036] Step B: feeding the nickel precipitation pre-liquid into the primary reaction tank 1 from the reserved pipe 11 at a flow rate of 25 L / min, and continuously and intermittently adding magnesium oxide powder into the primary reaction tank 1 through the intermittent parallel feeder 4;

[0037] Step C: The height difference between the liquid levels in the primary reaction tank 1 and the secondary reaction tank 2 is 50 cm, the reaction liquid in the primary reaction tank 1 overflows into the secondary reaction tank 2 through the first overflow pipe 5, and at the same time, the intermittent parallel feeder 4 continuously and intermittently adds magnesium oxide powder into the secondary reaction tank 2;

[0038] Step D: The height difference between the liquid levels in the secondary reaction tank 2 and the tertiary reaction tank 3 is 50 cm, and the reaction liquid in the secondary reaction tank 2 overflows into the tertiary reaction tank 3 through the second overflow pipe 6, and at the same time, the intermittent parallel feeder 4 continuously and intermittently adds sodium hydroxide powder into the tertiary reaction tank 3;

[0039] Step E: The reaction liquid in the tertiary reaction tank 3 overflows into the thickener 8 through the third overflow pipe 7, and the total residence time of the pre-nickel precipitation liquid in the primary reaction tank 1, the secondary reaction tank 2 and the tertiary reaction tank 3 is 6 hours;

[0040] Step F: The liquid treated by the thickener 8 is input into the buffer tank 9, and the buffer tank 9 supplies the liquid into the filter press 10, and MHP is obtained after filtration by the filter press 10.

[0041] like Figure 2 As shown, the mass ratio of the magnesium oxide powder added in the primary reaction tank 1, the magnesium oxide powder added in the secondary reaction tank 2, and the sodium hydroxide powder added in the tertiary reaction tank 3 is 7-9:2-0.5:1-0.5; the inlet end of the first overflow pipe 5 is inserted into the primary reaction tank 1 and extends toward the bottom of the tank, and the outlet end of the first overflow pipe 5 is located on the top of the secondary reaction tank 2; the inlet end of the second overflow pipe 6 is inserted into the secondary reaction tank 2 and extends toward the bottom of the tank, and the outlet end of the second overflow pipe 6 is located at the top of the tertiary reaction tank 3. On the top of the reaction tank 3; the inlet end of the third overflow pipe 7 is inserted into the tertiary reaction tank 3 and extends to the bottom of the tertiary reaction tank 3, the outlet end of the third overflow pipe 7 is fluidly connected with the thickener 8, and a delivery pump is installed on the third overflow pipe 7; the first-stage reaction tank 1, the second-stage reaction tank 2 and the tertiary reaction tank 3 are all equipped with a stirring motor 12 through a support frame, and a stirring blade 13 is coaxially fixedly connected to the power output shaft of the stirring motor 12, and the stirring blade 13 is driven by the stirring motor 12 to stir.

[0042] like Figure 3-4As shown, the intermittent parallel feeder 4 includes a frame 41, a drive assembly 42, a first feed assembly 43, a second feed assembly 44 and a third feed assembly 45, the frame 41 is installed above the primary reaction tank 1, the drive assembly 42 is installed in the middle position of the frame 41, the first feed assembly 43, the second feed assembly 44 and the third feed assembly 45 are respectively installed on the frame 41 along the circumferential direction of the drive assembly 42, the drive assembly 42 drives the first feed assembly 43, the second feed assembly 44 and the third feed assembly 45 to open when the circumferential rotation, the first feed assembly 43, the second feed assembly 44 and the third feed assembly 45 are respectively connected to different powder storage tanks through the feed pipe 14, and the first feed assembly 43, the second feed assembly 44 and the third feed assembly 45 are respectively connected to the primary reaction tank 1, the secondary reaction tank 2 and the tertiary reaction tank 3 through the distribution pipe 15.

[0043] like Figure 4 , Figure 5 and Figure 6As shown, the structures of the first feeding component 43, the second feeding component 44 and the third feeding component 45 are the same; the first feeding component 43 includes a quantitative cylinder 431, a first baffle 432, a second baffle 434, a main rotating shaft 437, a secondary rotating shaft 441 and a linkage arm 440, the frame 41 is provided with a mounting hole, an elastic sleeve 16 is arranged in the mounting hole, the quantitative cylinder 431 is installed in the elastic sleeve 16, the first baffle 432 is slidably fitted on the top end of the quantitative cylinder 431, the second baffle 434 is slidably fitted on the bottom end of the quantitative cylinder 431, the first baffle 432 is provided with a first through hole 433 matching the inner diameter of the quantitative cylinder 431, the second baffle 434 is provided with a second through hole 435 matching the inner diameter of the quantitative cylinder 431, the positions of the first through hole 433 and the second through hole 435 are staggered, the main rotating shaft 437 is rotatably fitted on the frame 41 and is engaged with the quantitative cylinder 431 is parallel, the first end of the main rotating shaft 437 is fixedly connected to the first baffle 432 through the first swing arm 438, the secondary rotating shaft 441 is coaxially rotatably fitted in the second end of the main rotating shaft 437, the end of the secondary rotating shaft 441 is fixedly connected to the second baffle 434 through the second swing arm 444, one end of the linkage arm 440 is fixedly connected to the main rotating shaft 437, the other end of the linkage arm 440 extends toward the direction of the driving assembly 42 and is drivingly connected to the driving assembly 42, the main rotating shaft 437 is provided with a first torsion spring 439, one end of the first torsion spring 439 is fixedly connected to the main rotating shaft 437, and the other end of the first torsion spring 439 is fixedly connected to the frame 41, and a second torsion spring 442 is installed on the secondary rotating shaft 441, one end of the second torsion spring 442 is fixedly connected to the main rotating shaft 437, and the other end of the second torsion spring 442 is fixedly connected to the secondary rotating shaft 441.

[0044] like Figure 4-6As shown, the driving component 42 includes a driving motor 421, a driving column 422 and a turntable 423, the driving motor 421 is fixedly mounted on the frame 41, the driving column 422 is coaxially fixedly connected to the output shaft of the driving motor 421, and the turntable 423 is coaxially fixed to the end of the driving column 422; the driving column 422 is located between the first feeding component 43, the second feeding component 44 and the third feeding component 45, three driving arms 424 are installed on the outer circumferential surface of the driving column 422, and the axial positions of the three driving arms 424 on the driving column 422 are staggered with each other, and the linkage arm 440 of the first feeding component 43, the linkage arm 440 of the second feeding component 44 and the linkage arm 440 of the third feeding component 45 respectively correspond to the axial position of one of the driving arms 424; the linkage arm 440 rotates to drive the first swing arm 438 to swing around the main rotation axis 437.

[0045] like Figure 4 and Figure 7 As shown, a limiting block 443 is coaxially fixedly connected to the end of the secondary rotating shaft 441, a limiting groove 425 is opened on the surface of the turntable 423 along the circumferential direction, and three release grooves 426 with a width greater than the limiting groove 425 are opened in the circumferential direction of the limiting groove 425, the limiting groove 425 and the release groove 426 are connected, and the limiting block 443 is inserted and slidably fitted in the limiting groove 425.

[0046] The feed pipe 14 on the first feed assembly 43 is connected to the magnesium oxide powder storage tank, and its feed pipe 15 extends to the top of the primary reaction tank 1; the feed pipe 14 on the second feed assembly 44 is connected to another magnesium oxide powder storage tank, and its feed pipe 15 extends to the top of the secondary reaction tank 2; the feed pipe 14 on the third feed assembly 45 is connected to the sodium hydroxide powder storage tank, and its feed pipe 15 extends to the top of the tertiary reaction tank 3. The end of the feed pipe 14 is sealed and slidably fitted with the surface of the first baffle 432, and the edges of the first baffle 432 and the second baffle 434 are formed with convex edges to limit the swing range of the first baffle 432 and the second baffle 434.

[0047] Since it is necessary to add different amounts of powder to each level of the reaction tank, this can be achieved by controlling and adjusting the inner diameter of the quantitative cylinder 431. The specific working principle is as follows: Take the first feeding component 43 as an example for explanation. Figure 4 and Figure 5 As shown, the driving motor 421 drives the driving column 422, the rotating disk 423 and the three driving arms 424 located on the driving column 422 to rotate, and the three driving arms 424 are respectively installed at the upper, middle and lower positions of the driving column 422;

[0048] like Figure 5As shown, in the initial state, the second baffle 434 blocks the lower end of the quantitative cylinder 431, that is, the second through hole 435 is staggered with the lower end of the quantitative cylinder 431, the first through hole 433 on the first baffle 432 is aligned and connected with the upper end of the quantitative cylinder 431, and the quantitative cylinder 431 is filled with powder. When the driving arm 424 corresponding to the linkage arm 440 on the first feeding assembly 43 contacts the linkage arm 440, the linkage arm 440 is pushed to swing, so that the main rotating shaft 437 compresses the first torsion spring 439 and the second torsion spring 442 and rotates, and at the same time, the first swing arm 438 drives the first swing arm 438 to move ...1 to move the first swing arm 431 to move the first swing arm 431 to move the first swing arm 438 to move the first swing arm 438 to move the first swing arm 431 to move the first swing arm 431 to move the first swing arm 431 to move the first swing arm 438 The first baffle plate 432 is driven to swing, so that the first through hole 433 on the first baffle plate 432 is staggered with the metering cylinder 431, that is, the feed pipe 14 and the metering cylinder 431 are cut off; the auxiliary rotating shaft 441 is under the action of the limiting block 443 at its end, the cross-sectional shape of the limiting block 443 is rectangular, the thickness of the limiting block 443 matches the groove width of the limiting groove 425, the limiting block 443 can slide in the limiting groove 425, but cannot rotate, the limiting block 443 can achieve the limiting effect, the auxiliary rotating shaft 441 will not rotate at this time, as the turntable 423 continues to rotate, as shown in FIG. Figure 7 As shown, when the release slot 426 on the rotating disk 423 rotates to the position of the limiting block 443, the limiting block 443 loses its restriction, and the second baffle 434 moves rapidly under the action of the second torsion spring 442, so that the second through hole 435 is connected with the quantitative cylinder 431, and the powder in the quantitative cylinder 431 falls into the distribution tube 15. The second baffle 434 is fixed with an impact plate 436, and the impact plate 436 is used to impact the quantitative cylinder 431 to promote the discharge of all powders and enter the primary reaction tank 1. The structural principles of the other two feeding components are the same, and only the arrangement position of the linkage arm 440 is different. The driving column 422 rotates one circle to toggle the linkage arms 440 of the three feeding components to achieve feeding;

[0049] When the driving arm 424 passes over the linkage arm 440 , the main rotating shaft is reset under the action of the first torsion spring, and the first baffle plate 432 and the second baffle plate 434 are reset at the same time.

[0050] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the claims of this patent application.

Claims

1. A method for continuously preparing MHP from laterite nickel ore in multiple stages, characterized in that: The following steps are involved: Step A: subjecting laterite nickel ore to high pressure acid leaching to remove iron and aluminum to obtain a nickel precipitation pre-liquid; Step B: feeding the nickel precipitation pre-liquid into the primary reaction tank (1) from the reserved tube (11), and continuously and intermittently adding magnesium oxide powder into the primary reaction tank (1) through the intermittent parallel feeder (4); Step C: the reaction liquid in the primary reaction tank (1) overflows into the secondary reaction tank (2) through the first overflow pipe (5), and at the same time, the intermittent parallel feeder (4) continuously and intermittently adds magnesium oxide powder into the secondary reaction tank (2); Step D: the reaction liquid in the secondary reaction tank (2) overflows into the tertiary reaction tank (3) through the second overflow pipe (6), and at the same time, the intermittent parallel feeder (4) continuously and intermittently adds sodium hydroxide powder into the tertiary reaction tank (3); Step E: the reaction liquid in the tertiary reaction tank (3) overflows into the thickener (8) through the third overflow pipe (7); Step F: The liquid treated by the thickener (8) is input into a buffer tank (9), and the buffer tank (9) supplies the liquid into a filter press (10), and MHP is obtained after filtering by the filter press (10).

2. The method for preparing MHP from laterite nickel ore in multiple stages according to claim 1, characterized in that: In step A, Ni in the nickel pre-precipitation solution 2+ The content is 0.5~10g / L.

3. The method for preparing MHP from laterite nickel ore in multiple stages according to claim 1, characterized in that: The total residence time of the nickel precipitation pre-liquid in the primary reaction tank (1), the secondary reaction tank (2) and the tertiary reaction tank (3) is 3 to 9 hours.

4. The method for preparing MHP from laterite nickel ore in multiple stages according to claim 3, characterized in that: The total residence time of the nickel precipitation pre-liquid in the primary reaction tank (1), the secondary reaction tank (2) and the tertiary reaction tank (3) is 5 to 7 hours.

5. The method for preparing MHP from laterite nickel ore in multiple stages according to claim 1, characterized in that: The mass ratio of the magnesium oxide powder added to the primary reaction tank (1), the magnesium oxide powder added to the secondary reaction tank (2), and the sodium hydroxide powder added to the tertiary reaction tank (3) is 7-9:2-0.5:1-0.

5.

6. The method for preparing MHP from laterite nickel ore in multiple stages according to claim 1, characterized in that: The difference in liquid level between the primary reaction tank (1) and the secondary reaction tank (2) is ≥10 cm, and the difference in liquid level between the secondary reaction tank (2) and the tertiary reaction tank (3) is ≥10 cm; the inlet end of the first overflow pipe (5) is inserted into the primary reaction tank (1) and extends toward the bottom of the tank, and the outlet end of the first overflow pipe (5) is located on the top of the secondary reaction tank (2); the inlet end of the second overflow pipe (6) is inserted into the secondary reaction tank (2) and extends toward the bottom of the tank, and the outlet end of the second overflow pipe (6) is located on the top of the tertiary reaction tank (3); the inlet end of the third overflow pipe (7) is inserted into the tertiary reaction tank (3) and extends toward the bottom of the tertiary reaction tank (3), the outlet end of the third overflow pipe (7) is in fluid communication with the thickener (8), and a delivery pump is installed on the third overflow pipe (7).

7. The method for preparing MHP from laterite nickel ore in multiple stages according to claim 1, characterized in that: The first-stage reaction tank (1), the second-stage reaction tank (2) and the third-stage reaction tank (3) are all equipped with stirring motors (12) via support frames, and stirring blades (13) are coaxially fixedly connected to the power output shaft of the stirring motor (12).

8. The method for preparing MHP from laterite nickel ore in multiple stages according to claim 1, characterized in that: The intermittent parallel feeder (4) comprises a frame (41), a drive assembly (42), a first feed assembly (43), a second feed assembly (44) and a third feed assembly (45), wherein the frame (41) is mounted above the primary reaction tank (1), the drive assembly (42) is mounted in the middle of the frame (41), the first feed assembly (43), the second feed assembly (44) and the third feed assembly (45) are respectively mounted on the frame (41) along the circumferential direction of the drive assembly (42), and the drive assembly (42) is mounted on the frame (41). When the part (42) rotates in a circle, it drives the first feeding component (43), the second feeding component (44) and the third feeding component (45) to open respectively; the first feeding component (43), the second feeding component (44) and the third feeding component (45) are respectively connected to different powder storage tanks through the feeding pipe (14); the first feeding component (43), the second feeding component (44) and the third feeding component (45) are respectively connected to the primary reaction tank (1), the secondary reaction tank (2) and the tertiary reaction tank (3) through the distribution pipe (15).

9. The method for preparing MHP from laterite nickel ore in multiple stages according to claim 8, characterized in that: The first feeding assembly (43), the second feeding assembly (44) and the third feeding assembly (45) have the same structure; the first feeding assembly (43) comprises a metering cylinder (431), a first baffle (432), a second baffle (434), a main rotating shaft (437), a secondary rotating shaft (441) and a linkage arm (440); a mounting hole is provided on the frame (41); an elastic sleeve (16) is provided in the mounting hole; the metering cylinder (431) is installed in the elastic sleeve (16); the first baffle (432) is slidably fitted in the main rotating shaft (437), and the second rotating shaft (441) is provided with a linkage arm (440); The second baffle (434) is slidably fitted on the top end of the quantitative cylinder (431), the first baffle (432) is provided with a first through hole (433) matching the inner diameter of the quantitative cylinder (431), the second baffle (434) is provided with a second through hole (435) matching the inner diameter of the quantitative cylinder (431), the first through hole (433) and the second through hole (435) are staggered, the main rotating shaft (437) is rotatably fitted on the frame (41) and is connected to the quantitative cylinder (431), the first end of the main rotating shaft (437) is fixedly connected to the first baffle (432) through a first swing arm (438), the secondary rotating shaft (441) is coaxially rotatably engaged in the second end of the main rotating shaft (437), the end of the secondary rotating shaft (441) is fixedly connected to the second baffle (434) through a second swing arm (444), one end of the linkage arm (440) is fixedly connected to the main rotating shaft (437), and the other end of the linkage arm (440) extends toward the direction of the driving component (42) and The main rotating shaft (437) is drivingly connected to the driving assembly (42), a first torsion spring (439) is arranged on the main rotating shaft (437), one end of the first torsion spring (439) is fixedly connected to the main rotating shaft (437), and the other end of the first torsion spring (439) is fixedly connected to the frame (41), and a second torsion spring (442) is installed on the secondary rotating shaft (441), one end of the second torsion spring (442) is fixedly connected to the main rotating shaft (437), and the other end of the second torsion spring (442) is fixedly connected to the secondary rotating shaft (441).

10. The method for preparing MHP from laterite nickel ore in multiple stages continuously according to claim 9, characterized in that: The driving assembly (42) comprises a driving motor (421), a driving column (422) and a rotating disk (423); the driving motor (421) is fixedly mounted on the frame (41); the driving column (422) is coaxially fixedly connected to an output shaft of the driving motor (421); and the rotating disk (423) is coaxially fixed to an end of the driving column (422); The driving column (422) is located between the first feeding component (43), the second feeding component (44) and the third feeding component (45); three driving arms (424) are installed on the outer circumferential surface of the driving column (422); the axial positions of the three driving arms (424) on the driving column (422) are staggered with each other; the linkage arm (440) of the first feeding component (43), the linkage arm (440) of the second feeding component (44) and the linkage arm (440) of the third feeding component (45) respectively correspond to the axial position of one of the driving arms (424); the linkage arm (440) rotates to push the first swing arm (438) to swing around the main rotation axis (437); A limiting block (443) is coaxially fixedly connected to the end of the secondary rotating shaft (441); a limiting groove (425) is provided on the surface of the rotating disk (423) in a circumferential direction; three releasing grooves (426) with a width greater than that of the limiting groove (425) are provided in the circumferential direction of the limiting groove (425); the limiting groove (425) and the releasing groove (426) are connected; and the limiting block (443) is inserted into and slidably fits in the limiting groove (425).

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