JP2019123915A - Method of producing nickel powder - Google Patents

Abstract

To provide a method of producing nickel powder having large bulk density by controlling particle diameter of the nickel powder.SOLUTION: The method of producing nickel powder is provided that comprises: an initial operation in which a nickel sulfate ammine complex solution containing nickel at concentration of 5 to 75 g/L or less is stored and temperature- raised together with a dispersant containing a seed crystal and lignin sodium sulfonate as components to a reaction temperature in a pressurized container equipped with a stirrer, hydrogen gas is then blown into the pressurized container and reduction reaction is performed, thereby obtaining nickel powder in which a complex ion is deposited in the solution on the seed crystal as a deposition; then following A operation is repeated at least once, thus nickel powder having median diameter of 50 to 100 μm and bulk density of 3.0 to 4.5 g/cmis obtained. (A operation) the complex solution in the same amount as the complex solution used during the initial operation, and all amount of the resulting nickel powder is stored into the pressurized container compression container, then temperature-raised to a prescribed reaction temperature, the hydrogen gas is then blown to the pressurized container and a reduction reaction is performed, thus the nickel powder having the deposition formed on the nickel powder is obtained.SELECTED DRAWING: None

Description

  The present invention relates to a method of producing high density nickel powder by hydrogen reduction.

  As a method of industrially producing nickel powder expected to be used as a conductive paste material or a positive electrode active material such as a nickel hydrogen battery, there is a method using a wet process. There are also various methods for industrially producing nickel powder in a wet process, in which a reducing agent is added to a solution containing nickel to reduce nickel ions in the solution to produce nickel powder. There is a way. Among them, a method of blowing hydrogen gas into an acidic solution having nickel as a complex for reduction can be industrially performed at low cost and is widely used.

In this method, as shown in Patent Document 1, an ammine complex solution containing nickel is placed in a pressure vessel, sealed and then heated, and hydrogen gas is blown into it to obtain nickel powder by reduction with hydrogen. It is
The obtained nickel powder tends to have a low density, and the low density nickel powder is apt to be bulky and takes handling time, and there is also a problem that impurities contained in the solution before reduction are easily precipitated. Therefore, nickel powder having a relatively large particle size of about 50 to 100 μm and a large bulk density, that is, a high density nickel powder is required at the same time.

However, Patent Document 1 discloses only the addition of an organic additive in the particle diameter control method, and it is difficult to obtain high density nickel powder only by this method, and another method is to be found. Was an issue.
Further, Non-Patent Document 1 discloses a method for industrially producing nickel powder, but no method for obtaining high density nickel powder has been found.

JP, 2015-140480, A

POWDER METALLURGY, 1958, no. 1/2, P. 40-52

  The present invention controls the particle size of nickel powder and provides a method for producing large bulk density nickel powder, but in particular provides a method for producing large bulk density nickel powder having a median diameter in the range of 50 to 100 μm. It is a thing.

A first invention of the present invention for solving the above-mentioned problems comprises a nickel sulfate sulfate solution containing nickel at a concentration of 5 g / L to 75 g / L, a seed crystal and sodium lignin sulfonate as components After the temperature is raised to a predetermined reaction temperature, hydrogen gas is blown into the pressure vessel to carry out a hydrogen reduction reaction, and the nickel complex ion in the nickel sulfate ammonium complex solution is After performing the initial operation to obtain nickel powder precipitated as precipitates on the seed crystals, the following procedure A is repeated at least once to obtain a median diameter of 50 μm to 100 μm, and 3.0 to 4 It is a method for producing a nickel powder characterized by obtaining a nickel powder having a bulk density of ⁵ g / cm ³ .

(A operation)
The nickel sulfate ammonium complex solution containing nickel at a concentration of 5 g / L or more and 75 g / L or less, which is the same amount as the nickel sulfate ammonium complex solution used in the first operation, and the total amount of nickel powder obtained in the previous operation After charging and storing in a pressure vessel equipped with a stirrer, heating, raising temperature and holding to a predetermined reaction temperature range, hydrogen gas is blown into the pressure vessel to carry out a hydrogen reduction reaction, and nickel precipitates on the nickel powder Operation to obtain formed nickel powder.

  According to a second aspect of the present invention, there is provided a nickel according to the first aspect, wherein the nickel has a weight ratio of 0.3 to 1.0 or less, and a particle diameter of 0.5 to 5.0 μm, relative to the weight of nickel in the nickel sulfate ammonium complex solution. It is a manufacturing method of nickel powder characterized by using powder as a seed crystal.

  The third invention of the present invention is characterized in that the dispersant consisting of sodium lignin sulfonate according to the first invention is added in a weight ratio of 0.03 to 0.13 or less with respect to the weight of the seed crystals. It is a manufacturing method of nickel powder.

  A fourth invention of the present invention is the method for producing nickel powder, wherein the predetermined reaction temperature in the first invention is in the range of 150 to 185 ° C.

  According to the present invention, it is possible to suppress the growth of particles and obtain a nickel powder having a large bulk density.

It is a graph showing transition of the bulk density by the addition amount of a dispersing agent, and repetition frequency. It is a graph showing transition of the particle size by the addition amount of a dispersing agent, and repetition frequency.

  The present invention relates to a method of blowing hydrogen gas into a sulfuric acid complex solution containing nickel ions and ammonia to hydrogen reduce nickel ions to obtain a nickel powder, wherein the obtained nickel powder is used as a seed crystal to form a sulfuric acid complex solution and a pressure vessel. It is characterized by repeatedly charging into the inside, blowing hydrogen gas, and performing a hydrogen reduction reaction to obtain a nickel powder, and at the same time, a dispersant containing sodium lignin sulfonate as a component before the first hydrogen reduction reaction. The seed crystals are dispersed by adjusting the amount thereof to disperse the seed crystals, and the particle diameter of the obtained nickel particles is controlled.

In the raw material used in the present invention, the nickel sulfate ammonium complex solution preferably has a nickel concentration of 5 g / L or more and 75 g / L or less, preferably sodium lignin sulfonate as the dispersant, and the weight ratio to the weight of seed crystals It is preferable to add in the range of 0.03 or more and 0.13 or less.
Further, the seed crystals added at the time of the first operation are nickel powder having a weight ratio of 0.3 or more and 1.0 or less and a particle diameter of 0.5 to 5.0 μm with respect to the weight of nickel in the nickel sulfate ammonium complex solution. Use

In the present invention, after the raw materials are stored in a pressurized container equipped with a stirrer, the temperature is raised and maintained at the reaction temperature, and the material is subjected to a hydrogen reduction reaction by blowing in hydrogen gas. The pressure is preferably in the range of 150 to 185 ° C., and the pressure of hydrogen gas blown into the vessel is in the range of 2.5 to 3.5 MPa, which is a desirable range as a range for efficiently advancing the hydrogen reduction reaction.
In addition, the time during which the reaction temperature is maintained is within the range of 10 to 120 minutes, and most of the nickel complex ions in the nickel sulfate ammonium complex solution can be reduced to nickel powder.

A nickel powder is produced by a hydrogen reduction reaction using the above raw materials, a pressure vessel and hydrogen gas, and the production method according to the present invention will be described below.
[First operation]
Prepare a nickel sulfate ammonium complex solution in which the nickel concentration is adjusted to a range of 5 to 75 g / L. The preparation of this nickel sulfate ammonium complex solution is carried out, for example, to form 1 liter of nickel sulfate ammonium complex solution, using 336 g of nickel sulfate hexahydrate serving as a nickel source and “ammonium sulfate to form an amine complex. The solution volume is made 1 liter by adding pure water to "330 g of" and "25% ammonia water" to 191 ml. A predetermined volume of a nickel sulfate ammonium complex solution is prepared at such a ratio.

Nickel sulfate having a weight ratio of 0.3 to 1.0 or less with respect to the weight of nickel in the prepared solution of nickel sulfate ammonium complex solution and using nickel powder having a particle diameter of 0.5 to 5.0 μm as a seed crystal Add to ammine complex solution.
Furthermore, a dispersant consisting of sodium lignin sulfonate is added at a weight ratio of 0.03 to 0.13 or less based on the weight of the seed crystals, and a slurry of a nickel source is prepared to produce a nickel powder by stirring. Do.

The prepared slurry is charged into a pressurized container equipped with a stirrer and stored, and then the pressurized container is sealed. The slurry stored in the closed pressure vessel is heated to 150 ° C to 185 ° C in the reaction temperature range, heated and maintained in a state of holding hydrogen gas introduced into the pressure vessel, and the slurry in the reaction temperature range From the nickel complex ion in the hydrogen reduction reaction, nickel powder precipitated as a precipitate on the seed crystals is formed.
It is desirable to maintain the pressure in the pressurized container by introduction of hydrogen gas at that time in the range of 2.5 to 3.5 MPa.

After the hydrogen reduction reaction by the hydrogen gas is performed for a predetermined time, the introduction of the hydrogen gas is stopped to stop the reaction, and the slurry in which the nickel powder is formed is cooled and cooled, and then the nickel powder is formed from the pressure vessel Discharge the slurry, separate solid and liquid, and collect nickel powder.
The recovered nickel powder is used as a seed crystal in "Operation A" described below, and the nickel powder produced and recovered by this operation A is again subjected to "A operation" as a seed crystal to produce nickel powder. The process is repeatedly performed until the obtained nickel powder has a predetermined particle size.

[A operation]
A total of the nickel sulfate ammonium complex solution containing nickel at a concentration of 5 g / L or more and 75 g / L or less, which is the same amount as the nickel sulfate ammonium complex solution used in the first operation, and the total amount of nickel powder obtained in the previous operation are stirred The reactor is charged with hydrogen and stored in a pressure vessel, heated to a predetermined reaction temperature range, heated and maintained, hydrogen gas is blown into the pressure vessel and subjected to a hydrogen reduction reaction to deposit nickel on the seed powder nickel powder. It is operation to obtain nickel powder which formed a thing.

By repeating the operation A at least once after the initial operation, it is possible to obtain a nickel powder having a median diameter of 50 μm to 100 μm and a bulk density of 3.0 to 4.5 g / cm ³ .
The various conditions such as the reaction temperature and the pressure in the pressure vessel in the operation A may be the same as the conditions in the “first operation”.

  Hereinafter, the present invention will be described using examples.

(Step 1)
22.5 g of nickel powder with a particle size (median diameter) of 0.5 to 5.0 μm, 336 g of nickel sulfate hexahydrate, 330 g of ammonium sulfate, and about 440 ml of pure water in 191 ml of 25% ammonia water; The original solution prepared to be 4 parts is added, and it is added to each original solution which collected 0.75 g, 1.5 g, 2.0 g and 3.0 g of sodium lignin sulfonate, and 4 samples with different dispersant concentration Prepared.

(Step 2)
Four samples prepared in the above-mentioned operation procedure 1 were put into inner cans of 3 L autoclave respectively, and the inner cans were installed in the autoclave.

(Step 3)
At a stirring speed of 750 rpm, the solution temperature in the autoclave was 185 ° C., and hydrogen gas was blown into the solution at 2 L / min so that hydrogen gas was 3.5 MPa in total pressure.

(Step 4)
After 60 minutes from the start of hydrogen blowing, the hydrogen gas blowing was stopped and the temperature of the autoclave was lowered.

(Step 5)
After lowering the temperature to 70 ° C. or less, the inner can was taken out, the liquid was filtered to collect nickel powder, and a part of the collected nickel powder was separated for evaluation, washed and vacuum dried.

(Step 6)
Four kinds of raw materials prepared so that the total volume of nickel powder was collected in procedure 5 and filled with 336 g of nickel sulfate hexahydrate, 330 g of ammonium sulfate, 191 ml of 25% ammonia water and pure water to make the liquid volume 1 liter The solution was made.

(Step 7)
The four types of stock solutions prepared in step 6 were subjected to nine repetitions (first to tenth times) of reduction reaction as in steps 2 to 6, respectively.
The particle diameter (median diameter) of the nickel powder that has been separated and dried in step 5 is measured with a particle size distribution analyzer every time each reduction reaction is completed, and the nickel powder is placed in a measuring cylinder for 3 minutes. After tapping, the bulk density was measured by a known method.

The measurement results are shown in FIG. 1 and FIG.
FIG. 1 shows the number of repetitions of the reduction reaction including the reduction reaction of the first operation on the horizontal axis, and the bulk density [g / cm ³ ] on the vertical axis, and FIG. 2 shows the reduction reaction including the reduction reaction of the first operation on the horizontal axis. The particle diameter (median diameter) gradually increases as the number of repetitions of reduction, and the number of repetitions of reduction reaction is increased so that the particle diameter [μm] is shown on the vertical axis, but 50 to 100 μm or less under the conditions of the present invention in the particle size, the bulk density was found to large nickel powder bulk density in the range of 3.0~4.5g / cm ³ is obtained.

(Comparative example 1)
Tests in procedure 2 and subsequent steps were performed in the same manner as in example 1 except that no dispersing agent was added in step 1 of example 1.

The measurement results show that there is almost no change in particle diameter (median diameter) even if the number of repetitions of reduction reaction is increased, and the bulk density is 1 to 4 with a particle diameter of 100 to 160 μm under the conditions of the present invention. It was found that a nickel powder in the range of 5 g / cm ³ was obtained.

Claims (4)

A solution of nickel ammine complex containing nickel at a concentration of 5 g / L or more and 75 g / L or less is stored in a pressure vessel equipped with a stirrer together with a seed crystal and a dispersant containing sodium lignin sulfonate as a component to obtain a predetermined reaction temperature After the temperature rise, hydrogen gas is blown into the pressure vessel to carry out a hydrogen reduction reaction to obtain a nickel powder in which nickel complex ions in the nickel sulfate ammonium complex solution are deposited as precipitates on the seed crystals. After doing
A nickel powder having a median diameter of 50 μm to 100 μm and a bulk density of 3.0 to 4.5 g / cm ³ is obtained by repeating the following operation A at least once: Production method.
(A operation)
The nickel sulfate ammonium complex solution containing nickel at a concentration of 5 g / L or more and 75 g / L or less, which is the same amount as the nickel sulfate ammonium complex solution used in the first operation, and the total amount of nickel powder obtained in the previous operation After charging and storing in a pressure vessel equipped with a stirrer, heating, raising temperature and holding to a predetermined reaction temperature range, hydrogen gas is blown into the pressure vessel to carry out a hydrogen reduction reaction, and nickel powder of the seed crystal Operation to obtain the nickel powder which formed the nickel deposit.   A nickel powder having a weight ratio of 0.3 to 1.0 or less and a particle diameter of 0.5 to 5.0 μm with respect to the weight of nickel in the nickel sulfate ammonium complex solution, which is used as a seed crystal The method for producing nickel powder according to claim 1.   The method according to claim 1, wherein the dispersant comprising sodium lignin sulfonate is added in a weight ratio of 0.03 to 0.13 or less with respect to the weight of the seed crystals. The method for producing nickel powder according to claim 1, wherein the predetermined reaction temperature is in the range of 150 to 185 ° C.

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