JP2019218591A - Recovery method of nickel powder - Google Patents

Abstract

To provide a recovery method of nickel powder that suppresses scaling inside a piping or sticking to a valve to stably generate nickel powder by a continued process, through providing a mechanism capable of cleaning the piping or the valve, in a method of reducing a nickel complex ion by hydrogen gas to obtain nickel powder.SOLUTION: A recovery method is for nickel powder included in reduction slurry containing the nickel powder generated by reducing, with hydrogen, a nickel complex ion contained in a raw material liquid supply containing a sulfuric acid nickel ammine complex solution continuously from the solution. The raw material liquid supply is mixed slurry further containing a seed crystal, the nickel powder has nickel precipitated on the seed crystal by the reduction process and the recovery method for nickel powder is conducted using a recovery apparatus appropriate for the recovery method.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for recovering nickel powder from a nickel ammine sulfate complex solution, and more particularly to a method for stably recovering a nickel powder slurry of a reduced slurry containing nickel powder generated from a high-temperature and high-pressure reaction tank.

  As a method for industrially producing nickel powder using a hydrometallurgical process, as shown in Patent Document 1, a nickel-containing raw material is dissolved in a sulfuric acid solution, and then a purification step of removing impurities contained in the solution. After that, ammonia is added to the obtained nickel sulfate solution to form an ammine complex of nickel. There is known a method for producing nickel powder by reducing nickel.

In the above-mentioned production method, since the reaction is carried out at a high temperature and a high pressure, a production method using a batch method is often used from the viewpoint of easy handling and equipment cost.
However, in a batch-type manufacturing method, a series of steps are performed in which a reaction vessel is opened, a solution is charged, a stopper is provided, the temperature is increased, the temperature and pressure are controlled, hydrogen gas is blown, reduced, cooled, and the reactants are taken out. The operation had to be performed for each stage, which required a great deal of labor and time, and the operation rate was low, which was not efficient. In addition, the effects of heating and cooling during and before and after the reaction cannot be ignored, and during this time, non-uniform precipitation called "scaling" and variation in particle size may occur. It was difficult to maintain the reaction availability and keep the product quality constant.

  In addition, the nickel powder obtained by the above-mentioned batch method has a problem in terms of impurity quality as compared with a plate (sheet) -like electric nickel obtained by general electrolytic smelting. Specifically, in order to obtain certification of a high-purity grade in LME (London Metal Exchange), which is an international trading market for nickel, the sulfur grade is required to be 0.01% by weight or less. However, in the nickel powder obtained by using the batch method, the sulfur grade may be higher than the above-mentioned high-purity LME grade specification, and it is difficult to use the nickel powder for completely replacing electric nickel. .

Therefore, in order to increase the productivity and obtain a certain quality, it has been proposed to generate nickel powder by continuous processing. Specifically, the above-mentioned nickel ammine complex solution or seed crystal is supplied to a high-temperature and high-pressure reactor, and hydrogen gas is blown under a constant high-temperature and high-pressure to generate nickel powder. It is to take out, to separate solid and liquid, and to recover nickel powder.
However, in the above method, when the slurry is directly taken out of the high-pressure reaction tank, there is a problem in terms of operational safety such as the slurry being scattered due to a sudden pressure reduction.

For this reason, a low-pressure tank (also called a “flash vessel”) is provided below the high-pressure reaction tank, and a valve (valve) provided at the entrance (liquid supply side) of the low-pressure tank is controlled, so that a high-temperature high-pressure tank is provided. An operation of safely reducing the pressure of the slurry discharged from the reaction tank to normal pressure is performed. There is also an advantage that the generated steam can be collected and used effectively by using the pressure reducing tank.
In actual operation, it is general that the high-temperature high-pressure reaction tank and the pressure-reducing tank are connected via a connection pipe. For this reason, it is preferable from the viewpoint of the pressure resistance of the connection pipe that the valve be provided on both the discharge port of the high-temperature and high-pressure reaction tank and the liquid supply side of the pressure-reducing tank.

However, when the nickel powder slurry or the like is supplied via the valve, there is a concern that a solid portion such as the nickel powder may bite or be caught in the valve mechanism.
In particular, an electromagnetic valve is generally used industrially to perform automatic control. However, in the case of a ferromagnetic powder such as nickel, there is a strong possibility that it reacts to the magnet of the electromagnetic valve and magnetically attaches to the opening / closing mechanism.

If it gets stuck or magnetically attached to the opening and closing mechanism of the valve, it cannot be controlled and the slurry is discharged from the high-temperature and high-pressure reactor in an unreacted state, or an excessive load is applied to the pressure-reducing tank. It becomes a problem.
Further, nickel powder was sometimes deposited inside the pipe in the middle of the connection pipe to form scale.

For this reason, it was necessary to provide a plurality of valves to enhance safety measures, and to frequently disassemble and clean the valves and pipes, which required labor and cost, making continuous operation difficult.
It is necessary to overcome such obstacles for the continuation of the generation of nickel powder. Therefore, the industrial recovery method of nickel powder has mainly been generated by a batch reaction with low productivity.

JP 2015-140480 A

  The present invention provides a method for obtaining nickel powder by reducing nickel complex ions with hydrogen gas, by providing a mechanism capable of washing pipes and valves, thereby suppressing scaling inside the pipes and biting into valves and stably. An object of the present invention is to provide a method for recovering nickel powder, which can produce nickel powder by a continuous process.

  A first invention of the present invention for solving the above-mentioned problem is to reduce the nickel complex ions contained in the nickel ammine complex solution continuously with hydrogen from a raw material supply solution containing the nickel ammine complex solution with hydrogen. A method for recovering nickel powder contained in a reduced slurry containing generated nickel powder, wherein the raw material supply liquid is a mixed slurry further containing a seed crystal, and the nickel powder is formed on the seed crystal by the reduction treatment. A method for recovering nickel powder, characterized in that the method comprises the following apparatus:

(Record)
A supply pipe with an on-off valve for supplying a raw material supply liquid, a hydrogen introduction pipe with an on-off valve for blowing hydrogen gas into the raw material supply liquid, and a discharge pipe with an on-off valve for discharging the reduced slurry; Storing and stirring, a reaction tank for forming a reduced slurry containing nickel powder generated by reducing nickel complex ions in the raw material supply liquid with the hydrogen gas,
An on-off valve with an on-off valve connected to a connection pipe having one end connected to the discharge pipe, and an on-off valve with an on-off valve connected to the solid-liquid separator are provided. The reduced slurry is supplied from the reaction tank through a connection pipe. After storing, the reduced slurry is reduced to normal pressure to be reduced to normal pressure, and a reduced pressure tank is discharged to a solid-liquid separator through the discharge pipe in order to recover nickel powder from the reduced slurry after normal pressure. ,
One end has a cleaning pipe with an on-off valve branching off at an intermediate portion of the connection pipe, and a cleaning water supply pipe with an on-off valve, stores cleaning water through the cleaning water supply pipe, and passes through the cleaning pipe. A washing water storage tank for supplying washing water to the reaction tank or the pressure-reducing tank, or both the reaction tank and the pressure-reducing tank;
The washing water is supplied from the washing water storage tank through the washing pipe to the connection pipe, and washing in the direction from the connection pipe to the pressure reduction tank and back washing in the direction from the connection pipe to the reaction tank are performed. Nickel powder recovery device with possible structure.

Further, in the second invention of the present invention, the back washing in the direction from the connection pipe to the reaction tank in the first invention causes the pressure of the washing water supplied from the washing water storage tank to decrease. than the internal pressure _{P R,} at a pressure of _P R +0.5 [MPa] from P R +0.2 [MPa], a method of recovering nickel powder characterized in that it is supplied to the wash pipe.

  In a third aspect of the present invention, a nickel powder characterized in that a filtrate obtained by solid-liquid separation of the reduced slurry is used as washing water supplied to the connection pipe according to the first or second aspect. It is a method of collecting.

  According to the present invention, in a method for recovering nickel powder by a process in which nickel complex ions are reduced by hydrogen gas and nickel powder is made continuous, by providing a mechanism capable of cleaning pipes and valves, the inside of nickel powder pipes is provided. In this case, the scaling and the biting of the valve are suppressed, and an industrially remarkable effect of stably generating nickel powder is achieved.

It is a schematic structure figure explaining the recovery device of nickel powder concerning the present invention.

  The present invention provides a method for recovering nickel powder using a nickel powder recovery device including a reaction tank and a pressure-reducing tank, wherein a pipe in the reaction tank and a reaction tank to a pressure-reducing tank are used in the recovery device at a high temperature and a high pressure. This is a recovery device that can perform "backwashing" that reduces the scaling of nickel metal into piping and various devices and the biting of nickel powder into valves and the like, and enables continuous operation of the reaction tank.

Specifically, the nickel complex ions in the nickel ammine complex solution are subjected to a reduction reaction with hydrogen gas at a predetermined high temperature and high pressure to precipitate nickel powder using a nickel powder recovery device 1 schematically shown in FIG. Since the process is performed by a continuous processing method, in order to stably perform a continuous process with high productivity, when the storage amount in the reaction tank 10 reaches an upper limit value of a predetermined level. , by opening the discharge valve V ₁ of the on-off valve provided in the discharge pipe 11 of the reaction vessel 10 is taken out reducing slurry 41 there nickel powder slurry was transferred through the connection pipe 13a, 13 in the step-down tank 20, a predetermined it is intended to repeat the operations of closing the discharge valve V ₁ When turned to the lower limit.

In doing so, the present invention supplies the cleaning water Ww through the cleaning pipe 14 from the cleaning water reservoir 30 which is separately provided, connecting the discharge pipe 11 of the pipe 13,13a and reaction tank 10, and the like discharge valve V ₁ by washing the easy part cause of obstruction, in particular, not only the cleaning of the on-off valve in which the inlet valve V ₂ to the connecting pipe 13 and the step-down tank 20 toward the buck tank 20, washing toward the reaction vessel 10 it is, connection pipe 13a and discharge valve V ₁ toward the reaction vessel _10, and discharge pipe 11, further washing water reaches to the inside of the reaction vessel 10, by performing the "reverse washing", effectively closed It is preventing.

For this reason, in the present invention, the cleaning water storage tank 30 for storing the cleaning water Ww is also configured to be pressurized to a pressure higher than the pressure of the reaction tank 10, and when performing “backwashing” at least toward the reaction tank 10. In addition, continuous operation can be performed without stopping operation in the reaction tank 10. The pressure _{P W} of the washing water during the washing respect intracisternal pressure _{P R} in the reaction vessel _10, as the P _W = P R +0.2 becomes _P W ₌ P R +0.5 [MPa] the pressure of the water, and the pressure of the washing water by (in the embodiment, nitrogen gas) atmosphere gas flowing through the pressure regulating valve GV ₂ to adjust the flow rate of the IG performed work to maintain the above range.

  The washing water Ww used for “washing” and “backwashing” is not only ordinary water W such as industrial water, but also a normal-pressure reduction slurry containing nickel powder generated by a reduction reaction, using a Nutsche, filter press, or centrifuge. The filtrate 51 separated from the nickel powder using a solid-liquid separation device such as a machine (for example, a solid-liquid separation device indicated by reference numeral 50) can also be used.

Next, the flow of the nickel powder in the recovery device 1 during “washing” and “backwashing” will be described.
Usually, a supply pipe 15, 15a, the supply valve _{V 4,} storing the mixed slurry (raw material liquid supply) 40 of a predetermined volume into the reaction vessel 10 through the supply valve _{V 4a.} The mixed slurry 40 may be supplied separately to the nickel ammine complex solution 60 and the seed crystal slurry 61 to the reaction tank 20 to form the mixed slurry 40 in the tank, or may be supplied in the form of a mixed slurry that is a mixture thereof. May be stored.
At the time of liquid supply, the discharge valve V ₁ was "closed" state, the supply valve V _4, V _4a is performed in "open".

After confirming that the mixed slurry 40 of predetermined volume in the reaction vessel is stored, with stirring to the mixed slurry 40 stored by stirrer M, mixing the hydrogen gas hydrogen introduction valve GV ₁ as a state "open" The reduced slurry 41 is formed by blowing into the slurry 40 to reduce nickel complex ions and precipitate nickel components to generate nickel powder.

Reducing slurry 41 that is formed, contains nickel powder, the discharge pipe 11, the discharge valve _{V 1,} the connection pipe 13a, the branch point A, the connection pipe 13, inlet valve _{V 2,} through the inlet pipe 21, the step-down tank 20 And reduced slurry 42 at normal pressure after being reduced to normal pressure. Thereafter, extraction pipe 18, through the evacuation valve V _6, is transferred to solid-liquid separator 50, it is solid-liquid separation of nickel powder and filtrate 51. In addition, a part or all of the filtrate 51 is transferred to the washing water storage tank 30 to be used as washing water.

  “Washing” and “backwashing” are performed according to the following timing and method. An example is shown below.

[Washing]
The reduced slurry 41 containing the nickel powder stored in the reaction tank 10 is discharged to the pressure reducing tank 20, and the reduced pressure tank 20 is changed to the normal pressure post-reduced slurry 42, and then the extraction valve V ₆ is “opened”. The entire amount is transferred to the solid-liquid separation device 50 to make the inside of the pressure reducing tank 20 “empty”. Then, the evacuation valve V ₆ is "closed", the connection is located at the C-side of the inlet valve V ₂ and cleaning water control valve V ₃ by flowing washing water Ww in the "open" state branching point A pipe 13 and the inflow valve V ₂ , and the step-down tank 20 storing the washing water Ww are washed. When cleaning is finished, or the washing water Ww is discharged to the outside from the drain provided in the step-down tank 20 (not shown), some evacuation valve V _6, shed solid-liquid separator 50, the cleaning thereof used.

[Backwash]
It can be performed simultaneously with or separately from the above “washing”.
In the case where the cleaning water adjustment valve V ₃ and the inflow valve V ₂ are kept “open”, the discharge valve V ₁ is kept “open”. the reaction vessel 10 side of the connection pipe 13a at a, the discharge valve V _1, the discharge pipe 11, by the washing water flows in the order of the reaction vessel 10, each part of the cleaning is performed. In addition, since the direction of the flow of the washing water is opposite to the direction in which the reduced slurry is transferred, it is referred to as “backwashing”.
Further, when performed separately, the inlet valve V ₂ is set to "closed" state, the wash water regulating valve V _3, by the discharge valve V ₁ is "open" state, facing the branch point A in the direction B , the reaction vessel 10 side of the connection pipe 13a, the discharge valve _{V 1,} the discharge pipe 11, and performs cleaning in the order of the reaction vessel 10.

[Washing water storage tank]
Washing water reservoir 30, supplies the washing water Ww, and the cleaning water supply valve V ₅ with the cleaning water supply pipe 16 of the on-off valve for storing, cleaning water Ww reaction vessel 10, the step-down tank 20, various pipes, accompanying comprising a cleaning water regulating valve V ₃ to play a discharge pipe 31 and the flow rate adjusted to supply the valve, the tank internal pressure regulating valve GV with ₂ to introduce an atmospheric gas IG to the wash water reservoir 30 further responsible for the pressure adjustment of the washing water It has a pressure adjusting pipe 17.
The transfer, supply, supply, withdrawal, and discharge of various solutions and slurries are performed using a high-pressure pump or the like not shown in FIG.

Hereinafter, the present invention will be described in more detail with reference to examples.
The embodiment is performed using the nickel powder recovery apparatus 1 shown in FIG.

Using a stainless steel reactor 10 (autoclave) having an internal capacity of 190 L and capable of holding high temperature and pressure, a nickel sulfate ammine complex solution having a nickel concentration of 82.5 g / L was pumped at a flow rate of 1.0 L / min by a high pressure pump (shown in the figure). ) Was continuously supplied into the reaction tank 10.
At the same time, a high-pressure slurry pump (not shown) was used at a supply rate of 0.5 L / min using a seed slurry 61 containing nickel powder having a particle size of 45 μm or less as a seed crystal at a concentration of 66 to 124 g / L. And continuously supplied into the reaction tank 10.

Incidentally, as shown in FIG. 1, the discharge valve V ₁ is an electromagnetic valve is provided in the discharge pipe 11 of the reaction vessel, the connecting pipe 13a, electromagnetic installed in the inlet pipe 21 of the step-down tank 20 through the connecting pipe 13 was connected to the inlet valve V ₂ is a valve.
Further, the cleaning pipe 14 is connected to the discharge pipe 31 of the washing water storage tank 30, the cleaning pipe 14 connecting pipe 13 at a branch point A through the wash water regulating valve V ₃ of the solenoid valve, connected to the connecting pipe 13a .

Inside the reaction tank 10, a cylinder or a hydrogen gas supply device, such as a hydrogen generator hydrogen gas supplied from the (not shown) (H ₂₎ is Fukikomeru structure, with the hydrogen supply valve GV ₁ on-off valve A hydrogen inlet tube 12 was provided.

The washing water reservoir 30 had adjustable water pressure of washing water so as to put blowing an inert gas (nitrogen gas) IG through the tank internal pressure regulating valve GV ₂ of the solenoid valve. Further, it is provided with a cleaning water supply valve V ₅ of the solenoid valve for supplying the filtrate 51 after the recovery of nickel powder by solid-liquid separation of industrial water W to reducing slurry.

Then, keeping the internal temperature of the reaction vessel 10 that Harikon the mixed slurry 40 of above 185 ° C., the hydrogen supply hydrogen gas by blowing (not shown) via a hydrogen feed pipe 12, the pressure P _R While maintaining the pressure in the range of 2.9 to 3.1 MPa, a reduction treatment was performed, and nickel was precipitated on the surface of the seed crystal to produce nickel powder, thereby forming a reduced slurry 41 as a nickel powder slurry.

  The reduction slurry 41 was intermittently drawn out toward the pressure-reducing tank 20 while continuing the liquid supply so that the volume of the content stored in the reaction tank 10 was maintained at 90 liters on average.

Specific extraction process, the washing water cleaning water supply valve V ₅ in the open state to the wash water reservoir 30 of FIG. 1 (Example of this time using industrial water) imposition of, intracisternal pressure regulating valve GV blowing high pressure nitrogen gas through _2, the tank internal pressure _{P R} of the washing water storage tank 30 has been boosted to 3.3～3.5MPa.
Further, the pressure _{P R} in the reaction vessel to adjust the blow amount of the hydrogen gas was maintained at 2.9～3.1MPa. When effusion amount becomes 92 liters reactor high temperature and high pressure conditions, reducing slurry 41 by opening the discharge valve V ₁ and the inflow valve V _2, it is discharged through the discharge pipe 11 from the reaction vessel 10 of the high-temperature, high-pressure state Is transferred to the pressure-reducing tank 20 through the connecting pipes 13a and 13; the pressure is reduced to normal pressure in the pressure-reducing tank 20; the liquid is separated and sent to the solid-liquid separator 50 to be separated into nickel powder and filtrate 51. did.

The discharge valve V ₁ and the inflow valve V ₂ at the time was reduced to 83 liters of stop sampling as "closed". Thereafter, the inflow valve V ₂ is "open", the discharge pipe 31 from the wash water reservoir 30 to the wash water regulating valve V ₃ as "open", and supplies the washing water Ww through washing pipe 14, the step-down tank direction of the connecting pipe and washed with 4 liter wash water once (C connection pipe 13 and the inlet valve V ₂ valve from a in Figure 1).

After washing the predetermined time, the inlet valve V ₂ is "closed", then the cleaning water regulating valve V ₃ in a few seconds as a "closed", the pressure was maintained connection pipe 13 to 3.3～3.5MPa. Next, the discharge valve V ₁ and the washing water regulating valve V ₃ at the same time as "open", the A in the reaction vessel 10 direction (Figure 1 high-temperature high-pressure state from the branch point A and the connecting pipe 13a of the B discharge valves V ₁ ) Was performed.
After a predetermined cleaning time, to complete the wash cycle discharge valve V ₁ and the washing water regulating valve V ₃ as "closed". The cleaning time from the connection pipe 13a through the discharge pipe 11 to the direction of the reaction tank 10 in a high temperature and high pressure state (the connection pipe 13a from A to B and the discharge valve V ₁ ) is such that the internal temperature change of the reaction tank 10 is 1.0 ° C. Adjusted to be less than.

After completion of the washing, the discharge of the reduced slurry 41, which is a nickel powder slurry, from the reaction tank 10 to the pressure reducing tank 20 and the water washing are repeated until the liquid level in the reaction tank 10 reaches the above-mentioned 92 liters. Was.
Due to the effect of this washing and back washing, continuous operation was possible without blocking pipes and valves even after 24H or more.

(Comparative Example 1)
A nickel sulfate ammine complex solution 60 having the same composition is supplied to the same reaction tank 10 as in Example 1 at the same rate of 1.0 L / min, and a seed crystal slurry 61 having the same particle size as the seed crystal is similarly supplied at a rate of 0.5 L / min. It was supplied at a flow rate. The temperature of the reaction vessel 10 also maintained at 185 ° C., the hydrogen gas blown, the pressure _{P R} in the reaction vessel 10 was subjected to reduction treatment as 3.1 MPa.

The nickel powder slurry was intermittently extracted from the pressure-reducing tank in the same manner as in Example 1 while maintaining the capacity of the reaction tank at the standard 90 L.
However, different from Example 1, the washing from the washing water storage tank 30 to the pressure reducing tank 20 side and the back washing to the reaction tank 10 side in a high temperature and high pressure state were not performed.

Time the reaction time of the reduction treatment has passed for 1 hour, and the discharge valve V ₁ of the discharge pipe 11 of the reaction vessel 10, the step-down tank 20 flows into valve V ₂ for supplying a reducing slurry 41 is, and nickel powder and reduction precipitation of nickel As a result, the valve could not be controlled, and the liquid volume in the reaction tank could not be maintained at 90 L.

(Comparative Example 2)
Using the same reaction vessel 10 and the nickel ammine complex solution and seed crystals sulfate as in Example 1, the same flow rate, while at a temperature, a discharge valve V ₁ and the inflow valve V ₂ is opened at the time when the same was 92 liters Through the discharge pipe 11 and the connection pipes 13 a and 13, the reduced slurry 41 was withdrawn intermittently into the pressure-reducing tank 20.
After discharging the reduced slurry 41 to the pressure reduction tank 20, “cleaning” was performed from the cleaning pipe 14 to the pressure reduction tank 20 side in the same manner as in Example 1.
However, "backwashing" from the washing pipe 14 to the reaction tank 20 was not performed.

As a result, the discharge valve V ₁ to discharge the reducing slurry from the reaction tank 10 after the lapse of 8 hours, can not be controlled to close by nickel powder and the reducing precipitated nickel, are unable to maintain the liquid volume of the high-temperature high-pressure reaction tank 90L Was.

DESCRIPTION OF SYMBOLS 1 Nickel powder collection apparatus 10 Reaction tank 11, 31 Discharge pipe 12 Hydrogen introduction pipe 13, 13a Connection pipe 14 Cleaning pipe 15, 15a Supply pipe 16 Cleaning water supply pipe 17 Pressure adjustment pipe 18 Extraction pipe 20 Pressure reduction tank 21 Inflow pipe 30 Washing water storage tank 40 Mixed slurry 41 Reduced slurry 42 After-pressure reduced slurry 50 Solid-liquid separator 51 Filtrate 60 Nickel ammine complex solution (feeding material)
61 seed slurry

A Branch point B Reaction tank direction C Pressure reducing tank direction M Stirrer V ₁ Discharge valve V ₂ Inflow valve V ₃ Wash water adjustment valve V ₄ , V _4a Raw material supply valve V ₅ Wash water supply valve V ₆ Extraction valve GV ₁ Hydrogen Supply valve GV ₂ tank pressure regulating valve W Water (industrial water, etc.)
Ww Wash water

Claims (3)

A method for recovering nickel powder contained in a reduced slurry containing nickel powder produced by subjecting a nickel complex ion contained in the nickel ammine complex solution to a reduction treatment with hydrogen continuously from a raw material supply solution containing the nickel ammine sulfate complex solution And
The raw material feed is a mixed slurry further containing a seed crystal,
The nickel powder has nickel precipitated on the seed crystal by the reduction treatment,
A method for recovering nickel powder, which is manufactured using the following recovery apparatus.
(Record)
A supply pipe with an on-off valve for supplying a raw material supply liquid, a hydrogen introduction pipe with an on-off valve for blowing hydrogen gas into the raw material supply liquid, and a discharge pipe with an on-off valve for discharging the reduced slurry,
A reactor for storing and stirring the raw material supply liquid, forming a reduced slurry containing nickel powder generated by reducing nickel complex ions in the raw material supply liquid with the hydrogen gas,
An on-off valve-equipped inflow pipe connected at one end to a connection pipe connected to the discharge pipe, and an on-off valve-equipped discharge pipe connected to the solid-liquid separator,
After storing the reduced slurry from the reaction tank via a connecting pipe, the reduced slurry is reduced to normal pressure to form a reduced slurry after normal pressure, and the discharge pipe is collected to recover nickel powder from the reduced slurry after normal pressure. A pressure-reducing tank discharged to the solid-liquid separation device through
One end has a cleaning pipe with an on-off valve branched at an intermediate portion of the connection pipe, and a cleaning water supply pipe with an on-off valve,
A washing water storage tank that stores washing water through the washing water supply pipe and supplies the washing water to the reaction tank or the pressure reducing tank through the washing pipe, or to both the reaction tank and the pressure reducing tank.
The washing water is supplied from the washing water storage tank through the washing pipe to the connection pipe, and washing in the direction from the connection pipe to the pressure reduction tank and back washing in the direction from the connection pipe to the reaction tank are performed. Nickel powder recovery device with possible structure. Backwashing in a direction toward the reaction vessel from the connection pipe, the pressure of the washing water supplied from the cleaning water reservoir, than the internal pressure P _R of the reactor, P _R +0.2 [MPa] The nickel powder recovery method according to claim 1, wherein the nickel powder is supplied to the cleaning pipe at a pressure of P _R +0.5 [MPa]. The method for recovering nickel powder according to claim 1 or 2, wherein a filtrate obtained by solid-liquid separation of the reduced slurry is used as washing water supplied to the connection pipe.

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