A circulating nickel dissolving device with a settler

Abstract

The present invention discloses a circulating nickel dissolution device with a settler, which includes a main reactor, a settler, an overflow pipe, a clear liquid return pipe, a discharge pipe, and a nickel powder return pipe. The main reactor includes an upper buffer zone, a middle accumulation reaction zone, and a bottom reflux inlet zone. A baffle is arranged vertically inside the overflow liquid inlet, the upper end of the baffle is connected to the top of the settler, and the lower end of the baffle extends to a position below the middle of the settler. In the device disclosed by the present invention, the baffle can not only isolate the overflow liquid inlet and the liquid outlet, but also play a role in guiding the overflow liquid entering the settler from the overflow liquid inlet, effectively preventing the overflow liquid mixed with nickel powder flowing in from the overflow liquid inlet from directly flowing out from the liquid outlet; the nickel powder return pipe is connected behind the reflux pump, which can not only use the thrust of the reflux pump to promote the circulation of nickel powder, but also allow the nickel powder not to pass through the reflux pump, thus avoiding the wear of the reflux pump by the nickel powder.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrometallurgy, and particularly to a circulating nickel dissolving device with a settler. Background Art

[0002] In the prior art, in a device for producing nickel sulfate by reacting nickel beans (or nickel powder, nickel blocks, nickel grains) with sulfuric acid solution, a circulating dissolution method is mostly adopted. The nickel solution circulated contains nickel powder. Due to its large density, the nickel powder causes great wear to the circulating pump, and the water pump is easily damaged. In a circulating nickel bean dissolver, the circulating pump is the heart. Once the circulating pump is damaged or under repair, the whole reaction has to be suspended forcedly. Summary of the Invention

[0003] Aiming at the problems existing in the prior art, the present invention provides a circulating nickel dissolving device with a settler, which specifically includes the following:

[0004] A circulating nickel dissolution device with a settler, comprising a main reactor, a settler, an overflow pipe, a clear liquid return pipe, a discharge pipe and a nickel powder return pipe. The main reactor includes an upper buffer zone, a middle accumulation reaction zone and a bottom reflux inlet zone. An overflow liquid outlet is provided on the side wall of the upper buffer zone. A porous support plate is arranged between the middle accumulation reaction zone and the bottom reflux inlet zone. The periphery of the support plate is connected to the inner wall of the main reactor. The function of the support plate is to support nickel beans. The porous support plate can facilitate the circulation of the solution on the one hand and prevent the nickel beans from being directly placed at the bottom of the reactor, resulting in insufficient reaction of the nickel beans accumulated at the bottom on the other hand. An acid feed inlet, a pure water feed inlet and a reflux inlet are provided on the side wall of the bottom reflux zone. An overflow liquid inlet and a liquid outlet are respectively provided on the opposite directions of the upper part of the side wall of the settler. A baffle is arranged vertically inside the overflow liquid inlet. The upper end of the baffle is connected to the top of the settler, and the lower end of the baffle extends to a position below the middle of the settler. The overflow liquid inlet and the liquid outlet are arranged on the opposite sides of the side wall of the settler, and a baffle is arranged at the overflow liquid inlet, which can play a guiding role in the overflow liquid entering the settler from the overflow liquid inlet, effectively preventing the overflow liquid mixed with nickel powder flowing in from the overflow liquid inlet from directly flowing out from the liquid outlet. A stirring device is arranged inside the settler. The stirring device stirs slowly, which can not only prevent the precipitation of nickel powder, but also prevent the nickel powder from entering the supernatant and running out from the discharge port due to too fast stirring. A nickel powder reflux outlet is arranged at the bottom end of the settler. The overflow liquid outlet of the main reactor is connected to the overflow liquid inlet of the settler through an overflow pipe. The reflux inlet of the main reactor is connected to the liquid outlet of the settler through a clear liquid return pipe. A reflux pump is arranged on the clear liquid return pipe. A nickel powder reflux inlet is arranged between the reflux pump on the clear liquid return pipe and the reflux inlet of the main reactor. The nickel powder reflux outlet of the settler is connected to the nickel powder reflux inlet of the clear liquid return pipe through a nickel powder return pipe. The specific connection method can adopt a tee connection. Here, the nickel powder return pipe is connected behind the reflux pump, which can not only use the thrust of the reflux pump to promote the circulation of nickel powder, but also allow the nickel powder not to pass through the reflux pump, thus avoiding the wear of the nickel powder on the reflux pump, greatly improving the service life of the circulation pump, and essentially improving the stability of the reaction system, which is beneficial to increasing the output. The liquid outlet of the settler is also connected to the discharge pipe. The discharge pipe and the clear liquid return pipe can be connected to the liquid outlet through a tee at the same time, or other connection methods can be adopted according to needs, which are not limited here.

[0005] Specifically, the height of the overflow liquid outlet of the main reactor is higher than the height of the overflow liquid inlet of the settler, and an overflow valve is arranged on the overflow pipe. The height of the overflow liquid outlet is higher than the height of the flowing liquid inlet, and the overflow liquid can flow into the settler from the overflow pipe under the action of gravity.

[0006] Specifically, the bottom of the settler is in the shape of a funnel that gradually narrows from top to bottom, and the nickel powder reflux outlet is arranged at the funnel opening of the funnel-shaped bottom of the settler; the stirring device includes a power device, a stirring rod connected to the power device, and a stirring paddle arranged at the bottom of the stirring rod. The stirring rod is arranged on the center line of the settler; the stirring paddle includes at least two paddle blades, one end of the paddle blade is connected to the stirring rod, and the paddle blade is arranged parallel to the funnel-shaped bottom of the settler. During operation, the stirring speed of the stirring device should not be too fast. Slow stirring can not only prevent nickel powder from precipitating but also prevent nickel powder from entering the supernatant and running out from the discharge port due to too fast stirring.

[0007] Specifically, a reflux valve is arranged on the clear liquid reflux pipe; a nickel powder reflux valve is arranged on the nickel powder reflux pipe; a discharge valve is arranged on the discharge pipe.

[0008] Specifically, the bottom of the bottom reflux liquid inlet area of the main reactor is in the shape of a funnel that gradually narrows from top to bottom. An emergency vent is also arranged in the bottom liquid inlet area. The emergency vent is arranged on the side wall or bottom of the bottom reflux liquid inlet area, preferably at the lowest point of the funnel-shaped bottom. The emergency vent is externally connected to an emergency vent pipe to facilitate complete discharge when emptying is required.

[0009] Specifically, it further includes a nitrogen-sealed feeding device. A feeding port is also arranged on the side wall of the upper buffer area of the main reactor, and the feeding port is connected to the nitrogen-sealed feeding device.

[0010] Specifically, a hydrogen peroxide feeding port and a liquid alkali feeding port are also arranged on the side wall of the upper buffer area below the feeding port. The hydrogen peroxide feeding port is connected to the hydrogen peroxide feeding pipe, and a hydrogen peroxide feeding valve is arranged on the hydrogen peroxide feeding pipe; the liquid alkali feeding port is connected to the liquid alkali feeding pipe, and a liquid alkali feeding valve is arranged on the liquid alkali feeding pipe.

[0011] Specifically, a negative pressure exhaust device is arranged on the top of the main reactor, and the negative pressure exhaust device is connected to a hydrogen detection and alarm instrument. The negative pressure exhaust device can timely discharge the hydrogen generated by the reaction to achieve safe production. The hydrogen detection and alarm instrument can monitor the hydrogen concentration in the reaction system in real time and provide early warnings in a timely manner.

[0012] Advantages of the present invention:

[0013] (1) The overflow liquid inlet and the liquid outlet are arranged on opposite sides of the side wall of the settler, and a baffle is arranged at the overflow liquid inlet. The baffle can not only isolate the overflow liquid inlet and the liquid outlet but also play a role in guiding the overflow liquid entering the settler from the overflow liquid inlet, effectively preventing the overflow liquid mixed with nickel powder flowing in from the overflow liquid inlet from directly flowing out from the liquid outlet;

[0014] (2) The nickel powder reflux pipe is connected behind the reflux pump. It can utilize the thrust of the reflux pump to promote the circulation of nickel powder and also allow the nickel powder to bypass the reflux pump, thus avoiding the wear of the reflux pump by nickel powder, greatly increasing the service life of the circulation pump, essentially improving the stability of the reaction system, and being conducive to increasing the output. Description of the Drawings

[0015] Figure 1 It is a schematic structural diagram of the device disclosed in the present invention. Detailed Embodiments

[0016] The present invention will be described in detail below with reference to the drawings and specific embodiments. The following embodiments do not limit the content of the invention described in the claims in any way. In addition, all the contents of the configurations shown in the following embodiments are not necessarily essential for the solution of the invention described in the claims.

[0017] A circulating nickel dissolving device with a settler, comprising a main reactor, a settler 4, an overflow pipe 5, a clear liquid return pipe 6, a discharge pipe 7 and a nickel powder return pipe 8. The main reactor includes an upper buffer zone 1, a middle accumulation reaction zone 2 and a bottom return liquid inlet zone 3. An overflow liquid outlet is arranged on the side wall of the upper buffer zone 1. A porous supporting plate 9 is arranged between the middle accumulation reaction zone 2 and the bottom return liquid inlet zone 3. The periphery of the supporting plate 9 is connected with the inner wall of the main reactor. The function of the supporting plate 9 is to support nickel beans. The porous supporting plate 9 can facilitate the flow of the solution on the one hand, and on the other hand, it can also prevent the nickel beans from being directly placed at the bottom of the reactor, resulting in insufficient reaction of the nickel beans accumulated at the bottom. An acid feed port, a pure water feed port and a return inlet are arranged on the side wall of the bottom return liquid inlet zone 3. The acid feed port is externally connected to an acid feed pipe 18, and an acid feed valve is arranged on the acid feed pipe 18. The pure water feed port is externally connected to a pure water feed pipe 19, and a pure water feed valve is arranged on the pure water feed pipe 19. The acid solution and pure water are fed from the bottom of the main reactor from bottom to top, and then penetrate through the holes of the supporting plate 9 into the nickel beans accumulated thereon and react with the nickel beans, so that all the nickel beans accumulated in the middle accumulation reaction zone 2 can fully contact with the acid solution, making the reaction efficiency higher.An overflow liquid inlet and a liquid outlet are respectively arranged in opposite directions on the upper part of the side wall of the settler 4. A baffle plate 10 is arranged vertically inside the overflow liquid inlet. The upper end of the baffle plate 10 is connected to the top end of the settler 4, and the lower end of the baffle plate 10 extends to a position below the middle of the settler 4. The overflow liquid inlet and the liquid outlet are arranged on opposite sides of the side wall of the settler 4, and the baffle plate 10 is arranged at the overflow liquid inlet, which can play a role in guiding the overflow liquid entering the settler 4 from the overflow liquid inlet, effectively preventing the overflow liquid mixed with nickel powder flowing in from the overflow liquid inlet from directly flowing out from the liquid outlet; A stirring device 11 is arranged inside the settler 4. The stirring device 11 stirs slowly, which can not only prevent nickel powder from precipitating, but also prevent nickel powder from entering the supernatant and running out from the discharge port due to too fast stirring; A nickel powder return outlet is arranged at the bottom end of the settler 4; The overflow liquid outlet of the main reactor is connected to the overflow liquid inlet of the settler 4 through an overflow pipe 5; The return inlet of the main reactor is connected to the liquid outlet of the settler 4 through a clear liquid return pipe 6; A return pump 20 is arranged on the clear liquid return pipe 6. A nickel powder return inlet is arranged between the return pump 20 on the clear liquid return pipe 6 and the return inlet of the main reactor. The nickel powder return outlet of the settler 4 is connected to the nickel powder return inlet of the clear liquid return pipe 6 through a nickel powder return pipe 8. The specific connection method can adopt a tee connection. Here, the nickel powder return pipe 8 is connected behind the return pump 20, which can not only use the thrust of the return pump 20 to promote the circulation of nickel powder, but also allow nickel powder not to pass through the return pump 20, thereby avoiding the wear of the return pump 20 by nickel powder, greatly improving the service life of the circulation pump, and essentially improving the stability of the reaction system, which is beneficial to increasing the output; The liquid outlet of the settler 4 is also connected to a discharge pipe 7. The discharge pipe 7 and the clear liquid return pipe 6 can be connected to the liquid outlet through a tee at the same time, or other connection methods can be adopted according to needs, which are not limited here.

[0018] In an embodiment of the present invention, the height of the overflow liquid outlet of the main reactor is higher than the height of the overflow liquid inlet of the settler 4, and an overflow valve is arranged on the overflow pipe 5. The height of the overflow liquid outlet is higher than the height of the flowing liquid inlet, and the overflow liquid can flow into the settler 4 from the overflow pipe 5 under the action of gravity. Valves are arranged on all pipelines to facilitate the control of the inlet, outlet and circulation of materials.

[0019] In an embodiment of the present invention, the bottom of the settler 4 is in the shape of a funnel that gradually narrows from top to bottom, and the nickel powder reflux outlet is arranged at the funnel opening of the funnel-shaped bottom of the settler 4; the stirring device 11 includes a power device, a stirring rod connected to the power device, and a stirring paddle arranged at the bottom of the stirring rod. The stirring rod is arranged on the center line of the settler 4; the stirring paddle includes at least two paddle blades, one end of the paddle blade is connected to the stirring rod, and the paddle blade is arranged parallel to the funnel-shaped bottom of the settler 4. During operation, the stirring speed of the stirring device 11 should not be too fast. Slow stirring can not only improve the reaction efficiency but also prevent nickel powder from entering the supernatant and running out from the discharge port due to too fast stirring. The settler 4 is arranged in a funnel shape to prevent nickel powder from depositing in the corners at the bottom of the settler 4 and reduce the yield. The paddle blades of the stirring device 11 are arranged in a V shape centered on the stirring rod and parallel to the bottom of the funnel-shaped settler 4. On the one hand, it can prevent the funnel-shaped bottom from blocking the paddle blades and better realize the stirring function. On the other hand, when scraping the material at the funnel-shaped bottom is required, the height of the paddle blades can be adjusted to rotate the paddle blades to scrape the material at the bottom.

[0020] In an embodiment of the present invention, a reflux valve is arranged on the clear liquid reflux pipe 6; a nickel powder reflux valve is arranged on the nickel powder reflux pipe 8; a discharge valve is arranged on the discharge pipe 7. Valves are arranged on the pipelines to facilitate the control of the flow of materials.

[0021] In an embodiment of the present invention, the bottom of the bottom reflux liquid inlet area 3 of the main reactor is in the shape of a funnel that gradually narrows from top to bottom, and an emergency vent 12 is further arranged in the bottom liquid inlet area. The emergency vent 12 is arranged on the side wall or bottom of the bottom reflux liquid inlet area 3. The emergency vent 12 is externally connected to an emergency vent pipe. Preferably, the emergency vent 12 is arranged at the lowest point of the funnel-shaped bottom. The bottom reflux liquid inlet area 3 is arranged in a funnel shape and the emergency air defense port is arranged at the lowest point of the bottom, which is convenient for complete discharge when emptying is required.

[0022] In an embodiment of the present invention, a nitrogen-sealed feeding device 13 is further included, and a feeding port 14 is further arranged on the side wall of the upper buffer area 1 of the main reactor. The feeding port 14 is connected to the nitrogen-sealed feeding device 13.

[0023] In an embodiment of the present invention, a hydrogen peroxide feeding port and a liquid caustic feeding port are further arranged on the side wall of the upper buffer area 1 below the feeding port 14. The hydrogen peroxide feeding port is connected to the hydrogen peroxide feeding pipe 15, and a hydrogen peroxide feeding valve is arranged on the hydrogen peroxide feeding pipe 15; the liquid caustic feeding port is connected to the liquid caustic feeding pipe 16, and a liquid caustic feeding valve is arranged on the liquid caustic feeding pipe 16.

[0024] In one embodiment of the present invention, a negative pressure exhaust device 17 is provided at the top of the main reactor, and the negative pressure exhaust device 17 is connected to a hydrogen detection and alarm instrument. The negative pressure exhaust device 17 can also be equipped with a standby UPS power supply as needed. The negative pressure exhaust device 17 can timely discharge the hydrogen generated by the reaction to achieve safe production. The hydrogen detection and alarm instrument can monitor the hydrogen concentration in the reaction system in real time and provide early warnings in a timely manner.

[0025] In one embodiment of the present invention, a support plate 9 for supporting nickel beans is provided at the bottom of the main reactor. The support plate 9 is arranged at the boundary between the middle accumulation reaction zone 2 and the bottom reflux liquid inlet zone 3. The bottom reflux liquid inlet zone 3 below the support layer is a funnel-shaped trough with a V-shaped cross-section. Nickel powder solids and nickel sulfate liquid are mixed in the bottom reflux liquid inlet zone 3. An acid feed port and a pure water feed port are provided on the side wall of the bottom reflux liquid inlet zone 3. A nitrogen sealed feed device 13 is provided at a position near the upper part of the side wall of the main reactor. A hydrogen peroxide feed port and a liquid alkali feed port are provided below the nitrogen sealed feed device 13. A negative pressure exhaust device 17 is provided at the top of the main reactor. A hydrogen detection and alarm instrument is provided on the negative pressure exhaust device 17. The negative pressure exhaust device 17 is externally connected to an alkali spray tower. An overflow liquid outlet is provided on the side wall of the main reactor opposite to the feed port position. The overflow liquid outlet is connected to a settler 4 through an overflow pipe 5. Nickel powder is discharged from the bottom of the settler 4, and nickel sulfate solution is discharged from the upper part.

[0026] When the device disclosed in the present invention is in use, with the continuous addition of sulfuric acid and pure water, the liquid level in the main reactor continuously rises, the nickel beans begin to dissolve, and hydrogen gas starts to be generated. The hydrogen gas carries the nickel sulfate solution and nickel powder and continuously rises. When the three-phase mixture of hydrogen gas, nickel sulfate solution, and nickel powder reaches the overflow port, the hydrogen gas continues to rise and is discharged from the negative pressure exhaust device 17, and the nickel sulfate solution and nickel powder mixture enters the settler 4. In the settler 4, the nickel powder settles to the bottom under the action of gravity, and the supernatant is the nickel sulfate solution. Thus, the gas-liquid-solid three-phase separation is achieved. The supernatant is pumped back into the main reaction tower through the reflux pump 20. The nickel powder slides down into the nickel powder reflux pipe 8 under the action of gravity. The supernatant reflux pipe 6 and the nickel sulfate reflux pipe form a Y shape, and the interface of the nickel powder reflux pipe 8 is arranged behind the reflux pump 20. The thrust of the supernatant reflux pump 20 can be used to pump the nickel sulfate-nickel powder mixture back into the main reaction tower. In this device, the overflow liquid inlet and the liquid outlet are arranged on two opposite sides of the side wall of the settler 4, and a baffle 10 is arranged at the overflow liquid inlet. The baffle 10 can not only isolate the overflow liquid inlet and the liquid outlet, but also play a guiding role in the overflow liquid entering the settler 4 from the overflow liquid inlet, and can effectively prevent the overflow liquid mixed with nickel powder flowing in from the overflow liquid inlet from directly flowing out from the liquid outlet. In addition, the nickel powder reflux pipe 8 is connected behind the reflux pump 20, which can not only use the thrust of the reflux pump 20 to promote the circulation of the nickel powder, but also allow the nickel powder not to pass through the reflux pump 20, thus avoiding the wear of the nickel powder on the reflux pump 20, greatly improving the service life of the circulation pump, and essentially improving the stability of the reaction system, which is beneficial to increasing the output.

[0027] When using this device to dissolve nickel beans, the acid used is sulfuric acid, and the optimal pH range is 0.5 - 1.0. When the hydrogen gas alarm detects that the hydrogen gas concentration > 10000 ppm, stop adding acid to the main reactor, and start adding liquid alkali and hydrogen peroxide solution into the main reactor to inhibit the generation of hydrogen gas (adding liquid alkali and hydrogen peroxide solution simultaneously can achieve double insurance to prevent the hydrogen gas concentration in the reaction device from being too high and causing an explosion hazard). When the hydrogen gas concentration < 6000 ppm, stop adding liquid alkali and hydrogen peroxide, and resume adding acid to maintain the pH at 0.5 - 1.0. When the reaction is completed, that is, when Ni 2+ > 125 g / L, discharge the nickel sulfate from the discharge port of the settler 4. The nickel sulfate solution enters an external storage tank through the discharge pipe 7, and hydrogen peroxide solution is added to the storage tank to oxidize the divalent iron in the reaction solution.

[0028] It should be noted that when using the device disclosed in the present invention to dissolve nickel beans, when the hydrogen gas concentration > 10000 ppm, stop adding acid to the main reactor, and start adding liquid alkali and hydrogen peroxide solution into the main reactor. The principle of adding hydrogen peroxide to inhibit the generation of hydrogen gas is as follows:

[0029] ①: Ni + H2O2 → NiO + H2O

[0030] ②: NiO + H2SO4 → NiSO4 + H2O

[0031] ③ = ① + ②: Ni + H2O2 + H2SO4 → NiSO4 + 2H2O

[0032] ④: Ni + H2SO4 → NiSO4 + H2↑

[0033] In the whole reaction system, the hydrogen production rate is only related to the acidity and the amount of nickel participating in the reaction. After adding hydrogen peroxide, in an acidic environment, reaction ① occurs preferentially. The nickel beans will first be oxidized by hydrogen peroxide to nickel oxide and then react with sulfuric acid. During this reaction process, due to the generation of water, the acidity decreases and the pH of the solution increases. Therefore, the hydrogen production rate will decrease. At the same time, due to the existence of reaction ③, the Ni participating in reaction ④ decreases, and the hydrogen production decreases.

[0034] In addition, it should be specifically noted that when using the device disclosed in the present invention to dissolve nickel beans, not all nickel beans are dissolved at one time. Instead, a part is dissolved each time. When the Ni in the reaction solution 2+ > 125 g / L, first discharge the nickel sulfate solution from the discharge port, and then supplement the feed from the nitrogen-sealed feeding device 13. After that, carry out the next cycle, and so on.

[0035] Unless otherwise clearly specified and limited, the terms "set" and "connect" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific situations.

[0036] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A circulating nickel dissolving device with a settler, characterized in that, It includes a main reactor, a settler, an overflow pipe, a clear liquid return pipe, a discharge pipe and a nickel powder return pipe. The main reactor includes an upper buffer zone, a middle accumulation reaction zone and a bottom return liquid inlet zone. An overflow liquid outlet is provided on the side wall of the upper buffer zone; a porous support plate is provided between the middle accumulation reaction zone and the bottom return liquid inlet zone, and the periphery of the support plate is connected to the inner wall of the main reactor; an acid feed inlet, a pure water feed inlet and a return inlet are provided on the side wall of the bottom return zone; on the opposite directions of the upper part of the side wall of the settler, an overflow liquid inlet and a liquid outlet are respectively provided. A baffle is arranged vertically inside the overflow liquid inlet, the upper end of the baffle is connected to the top end of the settler, and the lower end of the baffle extends to a position below the middle of the settler; a stirring device is arranged inside the settler; a nickel powder return outlet is provided at the bottom end of the settler; the overflow liquid outlet of the main reactor is connected to the overflow liquid inlet of the settler through the overflow pipe; the return inlet of the main reactor is connected to the liquid outlet of the settler through the clear liquid return pipe; a return pump is provided on the clear liquid return pipe, and a nickel powder return inlet is provided between the return pump on the clear liquid return pipe and the return inlet of the main reactor. The nickel powder return outlet of the settler is connected to the nickel powder return inlet of the clear liquid return pipe through the nickel powder return pipe; the liquid outlet of the settler is also connected to the discharge pipe; a hydrogen peroxide feed inlet and a liquid caustic feed inlet are also provided on the side wall of the upper buffer zone below the feed inlet. The hydrogen peroxide feed inlet is connected to a hydrogen peroxide feed pipe, and a hydrogen peroxide feed valve is provided on the hydrogen peroxide feed pipe; the liquid caustic feed inlet is connected to a liquid caustic feed pipe, and a liquid caustic feed valve is provided on the liquid caustic feed pipe; a negative pressure exhaust device is provided at the top of the main reactor, and the negative pressure exhaust device is connected to a hydrogen detection alarm.

2. The circulating nickel dissolving device with a settler according to claim 1, characterized in that, The height of the overflow liquid outlet of the main reactor is higher than the height of the overflow liquid inlet of the settler, and an overflow valve is provided on the overflow pipe.

3. The circulating nickel dissolving device with a settler according to claim 2, characterized in that, The bottom of the settler is in a funnel shape that gradually narrows from top to bottom, and the nickel powder return outlet is arranged at the funnel mouth of the funnel-shaped bottom of the settler; the stirring device includes a power device, a stirring rod connected to the power device, and a stirring paddle arranged at the bottom of the stirring rod. The stirring rod is arranged on the center line of the settler; the stirring paddle includes at least two paddle blades, one end of the paddle blade is connected to the stirring rod, and the paddle blade is arranged parallel to the funnel-shaped bottom of the settler.

4. A circulating nickel dissolving device with a settler according to claim 1, characterized in that, A return valve is provided on the clear liquid return pipe; a nickel powder return valve is provided on the nickel powder return pipe; a discharge valve is provided on the discharge pipe.

5. A circulating nickel dissolving device with a settler according to claim 1, characterized in that, The bottom of the bottom return liquid inlet zone of the main reactor is in a funnel shape that gradually narrows from top to bottom; an emergency vent is also provided in the bottom liquid inlet zone, and the emergency vent is arranged on the side wall or the bottom of the bottom return liquid inlet zone.

6. The circulating nickel dissolving device with a settler according to any one of claims 1-5, characterized in that, It further includes a nitrogen-sealed feeding device. A feed inlet is also provided on the side wall of the upper buffer zone of the main reactor, and the feed inlet is connected to the nitrogen-sealed feeding device.

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