WO2017150717A1

WO2017150717A1 - Nickel powder production method

Info

Publication number: WO2017150717A1
Application number: PCT/JP2017/008562
Authority: WO
Inventors: 佳智尾崎; 伸一平郡; 高石　和幸; 龍馬山隈
Original assignee: 住友金属鉱山株式会社
Priority date: 2016-03-04
Filing date: 2017-03-03
Publication date: 2017-09-08
Also published as: US20200338641A1; JPWO2017150717A1; AU2017226381B2; EP3424627A1; EP3424627A4; PH12018501870A1; CN108778578A; CA3016390A1; JP6816755B2; AU2017226381A1

Abstract

Provided is a production method in which a solution, a seed crystal, and hydrogen gas are continuously supplied into a reaction container so as to achieve production of a nickel powder, and the formed powder is continuously discharged, so that a high operating rate for reactions can be maintained while the product quality is maintained. The nickel powder production method is characterized by supplying a nickel sulfate ammine complex solution and a seed crystal into a reaction container, and by supplying hydrogen gas into the reaction container, so as to subject nickel complex ions in the nickel sulfate ammine complex solution to reduction treatment, thereby to produce a nickel powder, wherein the reduction treatment is characterized in that the temperature in the reaction container is controlled to be within a range of 150-185ºC while the nickel sulfate ammine complex solution is continuously supplied into the reaction container, and in that the supply amount of the hydrogen gas is controlled such that the internal pressure of the reaction container is kept within a range of 2.5-3.5 MPa.

Description

Method for producing nickel powder

The present invention relates to a method of obtaining nickel powder from a nickel sulfate ammine complex solution, and relates to a method of continuously adding a solution, hydrogen gas, etc. to a high-pressure vessel, and continuously discharging and collecting the nickel powder.

As a method for industrially producing nickel powder using a hydrometallurgical process, as shown in Patent Document 1, after dissolving a nickel-containing raw material in a sulfuric acid solution, a purified solution for removing impurities contained in the solution Through the process, ammonia is added to the resulting nickel sulfate solution to form a nickel ammine complex, then this nickel sulfate ammine complex solution is placed in a high-temperature, high-pressure vessel, and hydrogen gas is supplied to the nickel sulfate ammine complex solution. There is known a method for producing nickel powder by reducing nickel contained therein.

In the manufacturing method as described above, since the reaction is performed at a high temperature and a high pressure, a batch type manufacturing method is often used from the viewpoint of ease of handling and equipment cost. However, in the batch type production method, a series of processes are performed in which a reaction vessel is opened, a solution is charged, a cap is plugged, the temperature is raised, the temperature and pressure are controlled, hydrogen gas is blown in, reduced, cooled, and the reactant is taken out. It was necessary to perform the operation step by step, requiring a lot of labor and time, and the operation rate was low, which was not efficient. In addition, the effects of heating during and before and after the reaction are not negligible. During this time, non-uniform precipitation called graining and particle size variation may occur. When powder is generated, equipment is likely to be worn or clogged during handling, resulting in a situation where the operating rate is reduced. It was difficult to keep.

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

Japanese Patent Laid-Open No. 2015-140480

The present invention continuously supplies solution, seed crystals and hydrogen gas to a reaction vessel maintained at high temperature and high pressure to produce nickel powder, and discharges and collects the continuously produced powder. It is intended to provide a production method capable of maintaining a high reaction operation rate while maintaining a quality with small variation in particle size of fine nickel powder while sufficiently growing in purity.

According to a first aspect of the present invention for solving the above problems, a nickel sulfate ammine complex solution and a seed crystal are supplied to a reaction vessel, hydrogen gas is supplied to the reaction vessel, and the nickel sulfate ammine complex solution contains In the method for producing nickel powder, wherein nickel complex ions are reduced to produce nickel powder, the reduction treatment is performed by continuously supplying the nickel sulfate ammine complex solution to the reaction vessel. The temperature is controlled in the range of 150 ° C. or more and 185 ° C. or less, and the supply amount of the hydrogen gas is controlled so that the internal pressure in the reaction vessel is maintained in the range of 2.5 to 3.5 MPa. This is a method for producing nickel powder.

The second invention of the present invention reduces the nickel complex ions in the nickel sulfate ammine complex solution by supplying hydrogen gas into the reaction vessel and supplying the nickel sulfate ammine complex solution and seed crystal into the reaction vessel. In the method for producing nickel powder, which is processed to form nickel powder, the reduction treatment stores a slurry containing ammonium sulfate and nickel powder to form a liquid phase part and a gas phase part in the reaction container, and the reaction container contains Control of the internal pressure of the gas phase by supplying hydrogen gas to the slurry, continuous supply of the slurry containing seed crystals and the nickel sulfate ammine complex solution to the liquid phase, and the reaction vessel internal temperature of 150 ° C. or higher and 185 ° C. or lower While maintaining the internal pressure of the reaction vessel in the range of 2.5 to 3.5 MPa while controlling the amount of hydrogen gas supplied to the range of the nickel sulfate ammonium ammine complex solution. A method for producing a nickel powder which comprises reducing the Le complex ions.

The third invention of the present invention is characterized in that polyacrylic acid is added to the nickel sulfate ammine complex solution in the first or second invention so as to have a concentration of 0.5 to 1.0 g / liter. It is a manufacturing method of nickel powder.

A fourth invention of the present invention is a nickel powder manufacturing method, wherein the seed crystal in the first and second inventions uses nickel powder having an average particle size in the range of 0.1 to 100 μm.
According to a fifth aspect of the present invention, there is provided a nickel powder manufacturing method characterized in that the seed crystal in the first to third aspects uses nickel powder having an average particle diameter in the range of 0.1 to 10 μm. is there.

The sixth invention of the present invention is that the amount of seed crystals added in the first to fifth inventions is in the range of 1 to 100% by weight relative to the weight of nickel in the nickel sulfate ammine complex solution. It is the manufacturing method of the nickel powder characterized.

According to a seventh aspect of the present invention, the nickel sulfate ammine complex solution used for the reduction treatment in the first to sixth aspects is 0.5 to 5 based on the weight of the seed crystal in the nickel sulfate ammine complex solution. A method for producing nickel powder, comprising polyacrylic acid in a range of an amount of% by weight.

According to an eighth aspect of the present invention, there is provided nickel ammine sulfate containing seed crystals so that the reduction treatment in the first to seventh aspects of the invention has a reduction treatment reaction time in the reaction vessel of not less than 5 minutes and not more than 120 minutes. A method for producing nickel powder characterized in that a complex solution is continuously supplied to a reaction vessel.

According to the present invention, nickel powder in which nickel precipitates are formed and grown on the seed crystal can be formed by reduction treatment with nickel precipitation and the repetition thereof, and nickel powder with little variation in size can be continuously formed. Obtainable.
Also, nickel powder can be extracted and recovered from the solution as a fine powdery precipitate with low sulfur grade due to the effect of the dispersant, and depending on the combination of the particle size of the nickel powder and the dispersant concentration, a spherical and smooth surface Coarse nickel powder having can also be obtained.
The nickel powder produced in the present invention can be used as a nickel paste, which is an internal constituent material of a multilayer ceramic capacitor. In addition, the above-described reduction treatment with hydrogen is repeated to grow particles and produce high-purity nickel metal. This is a production method capable of maintaining a high reaction availability while maintaining a possible quality, and has a remarkable industrial effect.

It is an optical microscope photograph (x50) of the nickel powder which concerns on Example 1 of this invention. It is an optical microscope photograph (x100) of the nickel powder which concerns on Example 2 of this invention. It is a SEM photograph (x1000) of nickel powder concerning Example 3 of the present invention. It is a SEM photograph (x500) of nickel powder concerning Example 4 of the present invention. It is an optical microscope photograph of the nickel powder which concerns on Example 4 of this invention, (a) is * 50, (b) is the enlarged photograph (* 100).

The present invention adds a seed crystal to a nickel sulfate ammine complex solution, produces nickel powder by reduction treatment with hydrogen gas blown into a reaction vessel that is a pressurized vessel while continuously supplying it, and pressurizes the nickel powder. A nickel powder production method characterized by continuously discharging from a container. Further, by using a dispersant, it is possible to obtain high purity, uniform and fine nickel powder with low sulfur quality.
Hereafter, the manufacturing method of the nickel powder of this invention is demonstrated.

The nickel sulfate ammine complex solution used in the present invention is not particularly limited, but one or a mixture selected from nickel and cobalt mixed sulfide, crude nickel sulfate, nickel oxide, nickel hydroxide, nickel carbonate, nickel powder and the like. By subjecting nickel-containing materials, such as industrial intermediates, to nickel leaching solution (solution containing nickel) obtained by dissolving with sulfuric acid or ammonia, and subjecting it to liquid purification processes such as solvent extraction, ion exchange, and neutralization. A solution obtained by adding ammonia to a solution obtained by removing impurity elements from the solution to form a nickel sulfate ammine complex solution is suitable.

In the present invention, seed crystals are added to the nickel sulfate ammine complex solution to form a mixed slurry, which is subjected to a reduction treatment.
The seed crystal added here is preferably a powder having an average particle size of 0.1 μm or more and 100 μm or less, more preferably 0.1 μm or more and 10 μm or less.
In addition, it is preferable to use nickel powder as a substance that does not contaminate the final nickel deposit. The nickel powder used as the seed crystal can be produced, for example, by adding a reducing agent such as hydrazine to the nickel sulfate ammine complex solution.

Further, the weight of the seed crystal to be added is preferably 1% by weight or more and 100% by weight or less based on the weight of nickel in the nickel sulfate ammine complex solution. If the amount is less than 1% by weight, the effect of suppressing non-uniform precipitation cannot be sufficiently obtained, and even if an amount exceeding 100% by weight is added, the effect is not affected and excessive addition is caused.

Then, a dispersing agent can be added in order to disperse the seed crystals in the mixed slurry.
The dispersant used here is not particularly limited as long as it is a polyacrylate, but sodium polyacrylate is preferred as an industrially available product.
When a dispersant is added, the addition amount is preferably in the range of 0.5 to 5% by weight with respect to the weight of the seed crystal to be added. If it is less than 0.5%, the dispersion effect cannot be obtained, and even if added over 5%, the dispersion effect is not affected, and the addition is excessive.
Alternatively, the polyacrylic acid to be added may be added so as to have a concentration of 0.5 to 1.0 g / liter relative to the amount of the nickel sulfate ammine complex solution. A seed crystal having a diameter of 0.1 μm or more and 10 μm or less is preferable.
In the present invention, for example, “˜” in the above description of 0.5 to 5% by weight indicates 0.5 to 5% by weight.

Next, a mixed slurry formed by adding seed crystals or seed crystals and a dispersant to a nickel sulfate ammine complex solution is stored in a slurry containing ammonium sulfate and nickel powder, and high pressure resistance and high temperature are controlled by hydrogen gas. The container is continuously charged into a reaction tank, and a liquid phase part and a gas phase part occupied by the mixed slurry are formed in the reaction tank. Alternatively, a slurry containing a seed crystal or a slurry containing a seed crystal and a dispersant, and a nickel sulfate ammine complex solution are stored in a slurry containing ammonium sulfate and nickel powder, and an internal pressure controlled by hydrogen gas is controlled. The slurry is continuously charged into the reaction tank to form a mixed slurry, and a liquid phase part occupied by the mixed slurry and a gas phase part whose internal pressure is controlled by hydrogen gas are formed in the reaction tank.

Then, the nickel complex ions contained in the nickel sulfate ammine complex solution were reduced by hydrogen gas in the mixed slurry in the reaction vessel continuously charged, and the nickel was deposited on the added seed crystal to grow. While making it nickel powder, the nickel powder slurry which is the slurry containing the grown nickel powder is formed, and the grown nickel powder slurry is discharged | emitted continuously.

The reaction temperature at this time is preferably in the range of 150 ° C. or higher and 185 ° C. or lower. If it is less than 150 degreeC, reduction efficiency will fall, and even if it exceeds 185 degreeC, there is no influence on reaction, rather, since loss, such as a heat energy, increases, it is unsuitable.

Furthermore, the pressure in the gas phase portion of the reaction tank during the reaction is preferably maintained in the range of 2.5 to 3.5 MPa. If it is less than 2.5 MPa, the reaction efficiency decreases, and if it exceeds 3.5 MPa, there is no influence on the reaction, and the loss of hydrogen gas increases.

By the reduction treatment accompanied by nickel precipitation under such conditions, nickel powder is formed and grown on the seed crystal, and nickel powder with little variation in size can be obtained continuously.
Moreover, nickel can be extracted and recovered from the solution as a fine powdery precipitate with a low sulfur grade due to the effect of the dispersant. Moreover, coarse nickel powder having a spherical and smooth surface can be obtained by a combination of the particle diameter of nickel powder and the concentration of the dispersant.

The nickel powder produced as described above can be used, for example, as a nickel paste, which is an internal constituent material of a multilayer ceramic capacitor. In addition, the particles are grown by repeating the hydrogen reduction described above, and high purity and suitable for handling. A uniform fine nickel metal of 20 μm or less can be produced.

Hereinafter, the present invention will be described using examples.

A pressure vessel (autoclave) with an internal volume of 190 liters was used as a reaction tank, and 90 liters of a solution slurry containing 269 g / L of ammonium sulfate and 100 g / L of nickel powder was put into this reaction tank, and the temperature was set with a lid. The temperature was maintained at 185 ° C., and then hydrogen gas was blown at a pressure of 3.5 MPa.

Next, an initial solution consisting of 150 g of ammonium sulfate per liter and a nickel sulfate ammine complex solution having a nickel concentration of 110 g / L is added to the pressurized container at a flow rate of 1 liter per minute and a nickel species having a slurry concentration of 300 g / L. The crystal slurry was added at a flow rate of 0.25 liters per minute to proceed with the reduction treatment.
The nickel powder having an average particle diameter of 1 μm was used as the seed crystal constituting the nickel seed crystal slurry. Moreover, hydrogen gas was blown in while controlling the internal pressure of the pressurized container to be 3.5 MPa.

The operation of continuously extracting the nickel powder slurry containing the nickel powder generated by the reduction treatment from the pressure container while controlling the liquid storage amount in the pressure container to be in the range of 90 liters ± 5 liters. Continued for hours. The reduction treatment reaction time in the reaction vessel was 75 minutes from the start of the initial solution and seed crystal slurry to the extraction of the nickel powder slurry.
As shown in Table 1-1, the nickel concentration in the extracted nickel powder slurry was 0.28 g / L, and the reduction rate (reaction rate), that is, the rate at which hydrogen gas was used for the nickel powder precipitation reaction, It was 99.6%.

As shown in Table 1-2, in the particle size distribution, the proportion of 100 μm to 300 μm accounted for 99% or more, and sufficiently grown nickel powder was obtained.
The overall particle size distribution is less than 0.1% over 300 μm, 91% over 150 μm and 300 μm or less, 8.3% over 100 μm and 150 μm or less, over 83 μm and over 100 μm. And those having a diameter of more than 45 μm and 75 μm or less showed a distribution of less than 0.1% and those having a diameter of 45 μm or less were 0.7%.
As shown in FIG. 1, it was confirmed that nickel powder with little variation in particle size distribution can be continuously produced although the shape of the particles is not constant and aggregation is observed. The sulfur grade was 0.062%.

Using the same reaction vessel as in Example 1, 90 liters of a solution slurry containing 205 g / L of ammonium sulfate, 1 g / L of polyacrylic acid, and 105 g / L of nickel powder was placed in this reaction vessel, and the lid was covered. The internal temperature was kept at 185 ° C.

Next, hydrogen gas was blown into the gas phase portion of the reaction vessel, and the pressure in the vessel was adjusted to 3.5 MPa.
Next, a starting solution comprising a nickel sulfate ammine complex solution having a nickel concentration of 83 g / L and ammonium sulfate having a concentration of 120 g / L is supplied to the reaction vessel at a flow rate of 1 liter per minute, and at the same time, the slurry concentration is 150 g / L. The nickel seed slurry of L was continuously supplied to the reaction vessel at a flow rate of 0.5 liters per minute to proceed the reduction treatment.
In addition, the nickel powder which comprises a nickel seed crystal slurry used that whose average particle diameter is 1 micrometer. Moreover, hydrogen gas was blown in while controlling the internal pressure of the reaction vessel to be 3.5 MPa.

The reduced slurry was continuously extracted while controlling the amount of liquid stored in the reaction vessel to be in the range of 90 liters ± 5 liters, and this operation was continued for 16 hours. The extracted reduced slurry was solid-liquid separated into a nickel powder and a filtrate using a Nutsche, and the obtained nickel powder was washed and vacuum dried. The reduction treatment reaction time in the reaction vessel was 60 minutes from the start of the initial solution and the seed crystal slurry to the extraction of the nickel powder slurry.
The reduction rate (reaction rate), that is, the rate at which hydrogen gas was used for the nickel powder precipitation reaction, was 98.9%.
The average particle diameter represented by D50 of the obtained nickel powder was 5.2 μm, which was finer than that of Example 1, but there was little variation (see FIG. 2). Furthermore, the sulfur quality was 0.003%, and a high purity nickel powder having a low sulfur quality that was below the LME grade specification of 0.01% was obtained.

In a reaction vessel having the same structure as in Example 1 and having a capacity of 90 liters, 205 g / L of ammonium sulfate, 105 g / L of nickel powder, and 90 liters of a solution of 1 g / L of polyacrylic acid were added, and the temperature was maintained at 185 ° C., and hydrogen gas was blown in. The pressure was 3.5 MPa.

Next, a starting solution composed of a nickel sulfate ammine complex solution having a nickel concentration of 83 g / L and ammonium sulfate contained at a concentration of 120 g / L is added to the pressure vessel at a rate of 1 liter / minute, and a slurry is also added. A nickel seed crystal slurry having a concentration of 150 g / L was added at a rate of 0.5 l / min. The starting nickel sulfate ammine complex solution was added at a concentration of 1 g / L of polyacrylic acid and supplied to the reaction vessel. Hydrogen gas was blown in so that the pressure in the pressurized container was 3.5 MPa. The average particle diameter of the nickel powder constituting the extracted nickel powder slurry was 5.9 μm.

The nickel powder slurry was continuously extracted while controlling the amount of liquid in the pressurized container in the range of 90 liters ± 5 liters, and this operation was continued for 12 hours. The reduction treatment reaction time in the reaction vessel was 60 minutes from the start of the initial solution and the seed crystal slurry to the extraction of the nickel powder slurry.
At this time, the reduction rate, that is, the reaction rate was 96.8%.
The sulfur grade was 0.003%, which was lower than the LME grade specification of 0.01%.
The particle size was 6.4 μm at D50, and very fine powder could be stably obtained as seen in FIG.

Into the reaction vessel having the same capacity of 90 liters as in Example 1, 200 g / L of ammonium sulfate, 11 g / L of nickel powder, and 90 liters of a starting solution of 0.1 g / L of polyacrylic acid were put, and the temperature was maintained at 185 ° C., and hydrogen gas was supplied. The blowing pressure was 3.5 MPa.

A nickel sulfate ammine complex solution having a nickel concentration of 83 g / L and a starting solution having a composition of ammonium sulfate concentration of 360 g / L were added to the reaction vessel at a flow rate of 1 liter / min, and a nickel seed crystal slurry having a concentration of 33 g / L was added. Added at a rate of 0.5 liters / minute. Moreover, hydrogen gas was blown so that the pressure of the pressurized container was maintained at 3.5 MPa, and the reduction treatment was advanced.

The operation of continuously extracting the reduced nickel powder slurry from the reaction vessel was continued for 6 hours while controlling the amount of liquid stored in the reaction vessel to be in the range of 90 liters ± 5 liters. The average particle diameter of the nickel powder constituting the 33 g / L nickel seed crystal slurry is 53 μm, and the reduction treatment reaction time in the reaction vessel is 60 minutes from the start and introduction of the seed crystal slurry to the extraction of the nickel powder slurry. Met.

The reduction rate or reaction rate was 89.0%.
The recovered nickel powder had a sulfur grade of 0.01%, which satisfied the LME grade specification of 0.01%.
Further, the particle diameter was 78.0 μm at D50, and a sufficiently grown nickel powder was obtained. As shown in FIGS. 4 and 5, the surface of the nickel powder was very smooth and spherical.

A pressure vessel (autoclave) with an inner volume of 190 liters and titanium lined on the inner wall of the vessel was used as a reaction vessel (reaction vessel). 90 liters of a solution slurry containing a powder at a concentration of 105 g / liter was put in, and the inside temperature was maintained at 185 ° C. with a lid.
Subsequently, hydrogen gas was blown into the gas phase portion of the reaction vessel, and the pressure in the vessel was adjusted to 3.5 MPa. Next, a nickel sulfate ammine complex solution having a nickel concentration of 83 g / liter and a solution having an ammonium sulfate concentration of 120 g / liter are supplied to the reaction vessel at a flow rate of 1 liter per minute, and at the same time, 150 g / liter of nickel powder is supplied. The slurry was continuously fed into the reaction vessel at a flow rate of 0.5 liters per minute.
In addition, the nickel powder which comprises a nickel powder slurry used that whose average particle diameter is 1 micrometer. Moreover, hydrogen gas was blown in while controlling the internal pressure of the reaction vessel to be 3.5 MPa.

Next, the nickel powder slurry was continuously extracted while controlling the liquid volume in the reaction vessel to be in the range of 90 liters ± 5 liters, and this operation was continued for 16 hours. The extracted nickel powder slurry was solid-liquid separated into nickel powder and filtrate using a Nutsche, and the obtained nickel powder was washed and vacuum dried.

The reduction rate (reaction rate), that is, the rate at which hydrogen gas was used for the nickel powder precipitation reaction, was 98.9%.
The obtained nickel powder was able to stably obtain a fine nickel powder of 5.2 μm with an average particle diameter represented by D50.

(Comparative Example 1)
A solution of the same composition was continuously supplied at the same flow rate except that it did not contain polyacrylic acid in the same reaction vessel as in Example 1, and reduced with hydrogen gas under the same conditions to obtain a nickel powder slurry. The powder slurry was solid-liquid separated to obtain nickel powder. The reduction rate or reaction rate was 99.6%.

In the particle size distribution of the obtained nickel powder, the ratio of 100 μm to 300 μm occupies 99% or more, but the total particle size distribution is less than 0.1%, more than 300 μm and less than 300 μm. 91%, more than 100μm and less than 150μm 8.3%, more than 75μm and less than 100μm and less than 45μm and less than 75μm are both less than 0.1% and less than 45μm Shows a distribution of 0.7%, and nickel powder as fine as the present invention could not be obtained.
As described above, it was confirmed that fine nickel powder can be obtained continuously and efficiently by using the method of the present invention.

Claims

A nickel sulfate ammine complex solution and a seed crystal are supplied to a reaction vessel, hydrogen gas is supplied to the reaction vessel, and nickel powder in the nickel sulfate ammine complex solution is reduced to produce nickel powder. In the method for producing nickel powder,
While the reduction treatment continuously supplies the nickel sulfate ammine complex solution to the reaction vessel,
Controlling the temperature in the reaction vessel to a range of 150 ° C. or more and 185 ° C. or less,
A method for producing nickel powder, characterized in that the supply amount of hydrogen gas is controlled so that the internal pressure in the reaction vessel is maintained in the range of 2.5 to 3.5 MPa.
Hydrogen gas is supplied into the reaction vessel, and nickel sulfate ammine complex solution and seed crystal are supplied into the reaction vessel to reduce nickel complex ions in the nickel sulfate ammine complex solution, thereby producing nickel powder. In the method for producing nickel powder,
The reduction treatment is
Storing a slurry containing ammonium sulfate and nickel powder to form a liquid phase part and a gas phase part in the reaction vessel, and controlling the internal pressure of the gas phase part by supplying hydrogen gas into the reaction vessel;
Continuous supply of slurry containing seed crystals and nickel sulfate ammine complex solution to the liquid phase part;
Control of the temperature in the reaction vessel to a range of 150 ° C. or higher and 185 ° C. or lower;
The nickel complex ion in the nickel sulfate ammine complex solution is reduced while controlling the supply amount of the hydrogen gas to maintain the internal pressure in the reaction vessel in the range of 2.5 to 3.5 MPa. Powder manufacturing method.
3. The method for producing nickel powder according to claim 1, wherein polyacrylic acid is added to the nickel sulfate ammine complex solution so as to have a concentration of 0.5 to 1.0 g / liter.
The method for producing nickel powder according to claim 1 or 2, wherein the seed crystal uses nickel powder having an average particle diameter in the range of 0.1 to 100 µm.
The method for producing nickel powder according to any one of claims 1 to 3, wherein the seed crystal uses nickel powder having an average particle diameter in the range of 0.1 to 10 µm.
6. The seed crystal according to claim 1, wherein the seed crystal is added in an amount ranging from 1 to 100% by weight based on the weight of nickel in the nickel sulfate ammine complex solution. Of manufacturing nickel powder.
The nickel sulfate ammine complex solution subjected to the reduction treatment contains polyacrylic acid in an amount range of 0.5 to 5% by weight with respect to the weight of the seed crystal in the nickel sulfate ammine complex solution. The method for producing nickel powder according to any one of claims 1 to 6.
Continuously supplying the nickel sulfate ammine complex solution containing the seed crystal to the reaction vessel so that the reduction treatment takes 5 to 120 minutes in the reduction reaction time in the reaction vessel. The method for producing nickel powder according to any one of claims 1 to 7, characterized in that: