U.S. patent application number 16/309209 was filed with the patent office on 2019-10-10 for nickel powder production method and nickel powder production device.
This patent application is currently assigned to SUMITOMO METAL MINING CO., LTD.. The applicant listed for this patent is SUMITOMO METAL MINING CO., LTD.. Invention is credited to Shin-ichi Heguri, Yoshitomo Ozaki, Kazuyuki Takaishi.
Application Number | 20190308249 16/309209 |
Document ID | / |
Family ID | 60783484 |
Filed Date | 2019-10-10 |
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United States Patent
Application |
20190308249 |
Kind Code |
A1 |
Takaishi; Kazuyuki ; et
al. |
October 10, 2019 |
NICKEL POWDER PRODUCTION METHOD AND NICKEL POWDER PRODUCTION
DEVICE
Abstract
Provided is a method with which it is possible to prevent
equipment, such as piping and valves, used to discharge and recover
a nickel powder-containing slurry from a high pressure reaction
tank from being damaged and trapping the nickel powder therein and
to enable continuous operation, thereby improving the productivity.
This nickel powder production method comprises a step of reacting a
nickel sulfate-amine complex solution with hydrogen gas under high
pressure in a reaction tank, thereby obtaining a nickel powder
slurry containing nickel powder. The method is characterized in
that the nickel powder slurry is discharged and transferred through
discharge piping from the reaction tank in which the nickel
powder-containing slurry has been produced, and then a washing
solution is supplied to the discharge piping at a predetermined
pressure to wash the discharge piping.
Inventors: |
Takaishi; Kazuyuki;
(Niihama-shi, JP) ; Ozaki; Yoshitomo;
(Niihama-shi, JP) ; Heguri; Shin-ichi;
(Niihama-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SUMITOMO METAL MINING CO., LTD. |
Tokyo |
|
JP |
|
|
Assignee: |
SUMITOMO METAL MINING CO.,
LTD.
Tokyo
JP
|
Family ID: |
60783484 |
Appl. No.: |
16/309209 |
Filed: |
June 14, 2017 |
PCT Filed: |
June 14, 2017 |
PCT NO: |
PCT/JP2017/021980 |
371 Date: |
December 12, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01J 3/02 20130101; B22F
9/26 20130101 |
International
Class: |
B22F 9/26 20060101
B22F009/26 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 21, 2016 |
JP |
2016-122309 |
Claims
1. A nickel powder production method, the method comprising
reacting a nickel sulfate-amine complex solution with hydrogen gas
under a high pressure in a reaction tank to obtain a nickel powder
slurry containing nickel powder, wherein the nickel powder slurry
is discharged and transferred through discharge piping from the
reaction tank in which the slurry containing nickel powder is
produced, and then a washing solution is supplied to the discharge
piping at a predetermined pressure to wash the discharge
piping.
2. The nickel powder production method according to claim 1,
wherein the washing solution is supplied to the discharge piping at
a pressure lower than an internal pressure of the reaction tank by
0.2 MPa to 1.0 MPa.
3. The nickel powder production method according to claim 1,
wherein a filtrate obtained by subjecting the recovered nickel
powder slurry to solid-liquid separation is used as the washing
solution.
4. A nickel powder production device in which a nickel
sulfate-amine complex solution is reacted with hydrogen gas under a
high pressure to obtain a nickel powder slurry containing nickel
powder, the device comprising: a reaction tank in which a nickel
sulfate-amine complex solution is reacted with hydrogen gas to
produce nickel powder; a depressurization tank that depressurizes
the nickel powder slurry discharged from the reaction tank to
normal pressure; discharge piping for connecting the reaction tank
and the depressurization tank and discharging the nickel powder
slurry from the reaction tank to the depressurization tank; and
washing piping that is connected to the discharge piping and
supplies a washing solution to the discharge piping.
5. The nickel powder production method according to claim 2,
wherein a filtrate obtained by subjecting the recovered nickel
powder slurry to solid-liquid separation is used as the washing
solution.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method of subjecting a
nickel sulfate-amine complex solution to hydrogen reduction to
obtain nickel powder, and more specifically, to a nickel powder
production method and a nickel powder production device which are
capable of stably discharging a nickel powder slurry produced in a
reaction tank.
BACKGROUND ART
[0002] As a method for industrially producing nickel powder, there
is a nickel powder production method in which a raw material
containing nickel is dissolved in a sulfuric acid solution, a
treatment of removing impurities contained in the raw material is
performed, ammonia is then added to the obtained nickel sulfate
solution to form nickel in the form of amine complex, and nickel in
the nickel sulfate-amine complex solution is reduced by bringing
the nickel sulfate-amine complex solution into contact with
hydrogen gas, for example, at a high temperature and a high
pressure around 150.degree. C. to 250.degree. C. and 2.5 MPa to 3.5
MPa to produce nickel powder (for example, Patent Document 1).
[0003] Such a method is a method by which a high quality nickel
metal can be efficiently obtained with a compact facility; on the
other hand, there is a problem in that continuous operation which
is industrially advantageous is difficult to perform since reaction
is performed using a high-pressure container.
[0004] That is, the raw material and hydrogen gas are relatively
easily supplied to a high-temperature high-pressure reaction tank;
on the other hand, when a discharge side is constantly opened to
external air, an internal pressure of the reaction tank easily
becomes equal to the external air, and reaction cannot be performed
under a high pressure. For this reason, it is necessary to
appropriately adjust the pressure inside the reaction tank while a
balance between supply and discharge is maintained.
[0005] In the related art, as a process of performing continuous
reaction under a high temperature and a high pressure, for example,
a high pressure acid leaching (HPAL) process as described in Patent
Document 2 is known in which nickel oxide ore is charged together
with sulfuric acid in an autoclave, a valuable metal such as nickel
contained in the ore in a trace amount is leached in a sulfuric
acid solution by heating the autoclave to about 250.degree. C., and
the valuable metal is recovered.
[0006] In the HPAL process, a flash vessel (depressurization tank)
and a flash valve (discharge valve) are provided at an ejection
side of the autoclave (reaction tank), control, for example, as
disclosed in Patent Document 3 or Patent Document 4 is performed,
and opening and closing of the flash valve are repeated while the
internal pressure of the reaction tank is managed, so that the
continuous operation is executed.
[0007] Such a method using the flash vessel and the flash valve is
an excellent method in which steam generated at the time of
depressurization is recovered as energy and used again. However, it
is not easy to apply the continuous operation using the reaction
tank in a high-pressure state as illustrated in the HPAL process to
a complexing reduction process of obtaining nickel powder by
subjecting the aforementioned nickel sulfate-amine complex solution
to hydrogen reduction.
[0008] The reason for this is that there is a problem in that,
since metal of nickel powder to be produced by reaction is fine and
hard, the metal of nickel powder easily wears out piping or a
member attached to the piping such as a valve when the metal of
nickel powder is discharged from the reaction tank and cost and
time and effort for maintenance are largely required.
[0009] In particular, when the pressure is intended to be
depressurized from the reaction tank to atmospheric pressure, a
flow velocity of a nickel powder-containing slurry passing through
the flash valve reaches a furious speed close to a velocity of
sound, frictional force significantly increases, and further, the
slurry is hit by an inner wall of the flash vessel when the slurry
is ejected and recovered, so that damage occurs.
[0010] Further, in the complexing reduction process, since a liquid
in the middle of the nickel powder being precipitated from the
solution is discharged from the reaction tank in some cases, the
liquid is precipitated also on the inner wall of the piping after
discharging to cause clogging, or the liquid is precipitated inside
a valve controlling discharging or the valve traps the nickel
powder therein so that opening and closing of the valve cannot be
performed.
[0011] For this reason, it is necessary to perform maintenance such
as frequent disassembling and washing of piping and a valve, and
thus the continuous operation for a long time is difficult to
perform. Further, there is no industrially actual case of the
continuous operation, batch reaction in which a liquid is replaced
from the reaction tank with respect to each reaction is a
mainstream in commercial production, and a problem of an
improvement in productivity arises. [0012] Patent Document 1:
Japanese Unexamined Patent Application, Publication No. 2015-212411
[0013] Patent Document 2: Japanese Unexamined Patent Application,
Publication No. 2005-350766 [0014] Patent Document 3: Japanese
Unexamined Patent Application, Publication No. 2010-59489 [0015]
Patent Document 4: Japanese Unexamined Patent Application,
Publication No. 2014-240524
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0016] The present invention is proposed in view of such
circumstances, and an object thereof is to provide a method capable
of preventing equipment, such as piping and valves, used to
discharge and recover a nickel powder-containing slurry from a
high-pressure reaction tank from being damaged and trapping the
nickel powder therein and enabling the continuous operation to
improve productivity.
Means for Solving the Problems
[0017] The present inventor has conducted intensive studies, and as
a result, found that the aforementioned problems can be solved by
discharging and transferring a slurry containing nickel powder
obtained in a reaction tank through discharge piping and then
supplying a washing solution at a predetermined pressure to the
discharge piping to perform a washing treatment, thereby completing
the present invention.
[0018] (1) A first invention of the present invention is a nickel
powder production method, the method including reacting a nickel
sulfate-amine complex solution with hydrogen gas under a high
pressure in a reaction tank to obtain a nickel powder slurry
containing nickel powder, in which the nickel powder slurry is
discharged and transferred through discharge piping from the
reaction tank in which the slurry containing nickel powder is
produced, and then a washing solution is supplied to the discharge
piping at a predetermined pressure to wash the discharge
piping.
[0019] (2) A second invention of the present invention is the
nickel powder production method in the first invention, in which
the washing solution is supplied to the discharge piping at a
pressure lower than an internal pressure of the reaction tank by
0.2 MPa to 1.0 MPa.
[0020] (3) A third invention of the present invention is the nickel
powder production method in the first or second invention, in which
a filtrate obtained by subjecting the recovered nickel powder
slurry to solid-liquid separation is used as the washing
solution.
[0021] (4) A fourth invention of the present invention is a nickel
powder production device in which a nickel sulfate-amine complex
solution is reacted with hydrogen gas under a high pressure to
obtain a nickel powder slurry containing nickel powder, the device
including: a reaction tank in which a nickel sulfate-amine complex
solution is reacted with hydrogen gas to produce nickel powder; a
depressurization tank that depressurizes the nickel powder slurry
discharged from the reaction tank to normal pressure; discharge
piping for connecting the reaction tank and the depressurization
tank and discharging the nickel powder slurry from the reaction
tank to the depressurization tank; and washing piping that is
connected to the discharge piping and supplies a washing solution
to the discharge piping.
Effects of the Invention
[0022] According to the present invention, it is possible to
prevent equipment, such as piping and valves, used to discharge and
recover a nickel powder-containing slurry from a high-pressure
reaction tank from being damaged and trapping the nickel powder
therein. Accordingly, time and effort and cost for maintenance are
reduced and continuous operation is enabled, so that productivity
can be improved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a diagram illustrating the flow of a nickel powder
production method and is a diagram illustrating the flow of a
solution or the like to various treatment tanks.
[0024] FIG. 2 is a diagram illustrating a configuration of a nickel
powder production device.
PREFERRED MODE FOR CARRYING OUT THE INVENTION
[0025] Hereinafter, a specific embodiment of the present invention
(hereinafter, referred to as "the present embodiment") will be
described in detail. Incidentally, the present invention is not
limited to the following embodiment, and various modifications can
be made within the range that does not change the spirit of the
present invention. Further, in the present specification, the
description "X to Y" (X and Y are arbitrary numerical values) means
"X or more and Y or less" unless otherwise specified.
<<1. Nickel Powder Production Method>>
[0026] A nickel powder production method according to the present
embodiment is a method of charging a nickel sulfate-amine complex
solution in a reaction tank, and reducing nickel ions to nickel in
the solution by the solution being brought into contact with
hydrogen gas under pressure, thereby obtaining a nickel powder
slurry containing nickel powder.
[0027] Specifically, in the production method, the nickel
sulfate-amine complex solution is supplied to the reaction tank and
the pressure of a gas phase part inside the reaction tank is
adjusted by continuous supply of hydrogen gas while a temperature
inside the reaction tank is maintained in a predetermined range, so
that nickel ions in the nickel sulfate-amine complex solution is
reduced to nickel under pressure. In the reaction tank, the nickel
powder as seed crystals can be added together with the nickel
sulfate-amine complex solution, and hydrogen reduction reaction is
caused by supplying a mixed slurry of the nickel sulfate-amine
complex solution and the nickel powder to the reaction tank, so
that nickel produced by reduction is precipitated on the surface of
the nickel powder as seed crystals.
[0028] According to such a method, it is possible to efficiently
produce nickel powder having a high quality and an optimum shape by
continuous operation.
(Regarding Hydrogen Reduction Reaction in Reaction Tank)
[0029] Specifically, FIG. 1 is a diagram illustrating the flow of a
nickel powder production method and illustrates the flow of a
solution or the like to various treatment tanks. As illustrated in
FIG. 1, in the production method, first, a mixed slurry of a nickel
sulfate-amine complex solution and nickel powder (nickel powder
slurry) as seed crystals is supplied to a reaction tank. Then,
hydrogen gas for reduction is continuously supplied to the reaction
tank in which the mixed slurry of a nickel sulfate-amine complex
solution and nickel powder as seed crystals is charged.
[0030] The nickel sulfate-amine complex solution is a solution
containing nickel in the form of an amine complex, and can be
obtained, for example, by adding ammonia gas or ammonia water
(NH.sub.4OH) to a nickel sulfate (NiSO.sub.4) solution.
[0031] When the nickel sulfate-amine complex solution is produced,
the concentration of ammonia to be added is not particularly
limited, but for example, it is preferable to add ammonia to be 1.9
or more in a molar ratio with respect to the nickel concentration
in the solution. According to this, it can be prevented that nickel
in the solution becomes nickel hydroxide deposition without forming
an amine complex.
[0032] As the nickel powder to be added as seed crystals, nickel
powder with an average particle size of 0.1 .mu.m to 300 .mu.m is
preferably used, and nickel powder with an average particle size of
10 .mu.m to 200 .mu.m is more preferably used. When the particle
size of the nickel powder as seed crystals is less than 0.1 .mu.m,
the nickel powder to be obtained is too fine, and thus there is a
possibility that the effect as seed crystals is not sufficiently
exhibited. On the other hand, when the particle size of the nickel
powder as seed crystals is more than 300 .mu.m, the nickel powder
is coarse, and thus the effect of suppressing abrasion of the
facility is not obtainable and it is economically disadvantageous
that such coarse nickel powder is prepared.
[0033] As the nickel powder as seed crystals, commercially
available nickel powder can be used, and nickel powder chemically
precipitated by a known method can be classified and used. Further,
produced nickel powder can also be repeatedly used. Incidentally,
the nickel powder as seed crystals is continuously supplied
together with the nickel sulfate-amine complex solution as a raw
material to the reaction tank by a supply device such as a slurry
pump.
[0034] The temperature inside the reaction tank, that is, the
reaction temperature of the hydrogen reduction reaction is set to a
range of 150.degree. C. to 250.degree. C. Further, the temperature
is set preferably to 150.degree. C. to 185.degree. C. The
temperature inside the reaction tank is adjusted, for example, by
heating using a heating device or the like, and is maintained. When
the reaction temperature is lower than 150.degree. C., reduction
efficiency of nickel ions in the nickel sulfate-amine complex
solution is degraded. On the other hand, even when the reaction
temperature is higher than 250.degree. C., the reduction reaction
is not affected, and instead, the loss of hydrogen gas to be
supplied to the reaction tank and the loss of thermal energy
occur.
[0035] In this production method, in a state where the temperature
of the reaction tank is maintained at 150.degree. C. to 250.degree.
C., hydrogen gas is continuously supplied to the gas phase part at
which the solution is not filled in the reaction tank. By supplying
the hydrogen gas in this way, the pressure of the gas phase part is
set, for example, to a range of 2.5 MPa to 3.5 MPa. Specifically,
hydrogen gas is directly blown to the gas phase part in the
reaction tank, for example, from a cylinder or the like, or is
blown into the slurry.
[0036] Regarding the pressure of the gas phase part, when the
internal pressure is less than 2.5 MPa, the efficiency of reduction
reaction of nickel ions is degraded. On the other hand, even by
setting a high pressure condition such that the internal pressure
is more than 3.5 MPa, the reduction reaction is not affected, and
instead, the loss of the supplied hydrogen gas increases.
[0037] As described above, in the nickel powder production method
according to the present embodiment, hydrogen gas is blown to the
mixed slurry of a nickel sulfate-amine complex solution and nickel
powder as seed crystals to adjust the pressure to a predetermined
pressure, so that nickel ions contained in the nickel sulfate-amine
complex solution is reduced to nickel under pressure. According to
this, nickel produced by reduction is precipitated on the surface
of the nickel powder supplied as seed crystals so that reduced
nickel powder can be obtained.
(Regarding Extraction of Nickel Powder Slurry)
[0038] Next, the nickel powder slurry containing nickel powder that
is a reacted slurry produced in the reaction tank is discharged and
extracted from the reaction tank to a depressurization tank. The
nickel powder slurry is produced by reduction reaction in the
reaction tank under pressure and has an extremely high pressure.
Therefore, by discharging and transferring such a nickel powder
slurry to the depressurization tank, the pressure is gradually
reduced in the depressurization tank, and for example, is set to
the same pressure as atmospheric pressure.
[0039] The reaction tank and the depressurization tank are
connected by piping (discharge piping) for transferring the nickel
powder slurry, and the nickel powder slurry ejected from the
reaction tank is discharged to the depressurization tank through
the discharge piping.
[0040] Herein, in the nickel powder production method according to
the present embodiment, the nickel powder slurry produced in the
reaction tank is discharged and transferred through the discharge
piping, and then a washing solution is supplied at a predetermined
pressure to the discharge piping to wash the inside of the
discharge piping or a valve provided in the discharge piping.
According to such a method, it is possible to wash and remove
nickel powder and other precipitates precipitated during the
process of discharging the nickel powder slurry, nickel powder
trapped in the valve, and the like, and it is possible to
effectively prevent abrasion and clogging of the piping and the
valves caused by the precipitated nickel powder, or the like.
According to this, time and effort and cost for maintenance can be
effectively reduced and the continuous operation is enabled, so
that productivity can be improved.
[0041] Incidentally, washing of the discharge piping using the
washing solution will be described in detail together with the
description of the configuration of a production device described
later.
(Regarding Recovery of Nickel Powder from Nickel Powder Slurry)
[0042] When the pressure of the nickel powder slurry is reduced in
the depressurization tank to atmospheric pressure, next, the nickel
powder slurry is extracted from the depressurization tank and
transferred to a solid-liquid separation tank.
[0043] In the solid-liquid separation tank, the nickel powder
slurry is subjected to a solid-liquid separation treatment based on
a known method, so that the nickel powder slurry is separated into
nickel powder and a filtrate to recover nickel powder.
Incidentally, although specifically described later, the filtrate
separated herein can be reused as the washing solution of the
discharge piping in order to transfer the nickel powder slurry from
reaction tank to the depressurization tank.
<<2. Nickel Powder Production Device>>
[0044] Next, a production device for performing the nickel powder
production method will be described in more detail. The nickel
powder production method according to the present embodiment can be
performed using a nickel powder production device to be described
specifically below.
[0045] FIG. 2 is a diagram illustrating an example of the
configuration of a nickel powder production device. This nickel
powder production device 1 is a production device in which a nickel
sulfate-amine complex solution is reacted with hydrogen gas under a
high pressure to obtain a nickel powder slurry containing nickel
powder.
[0046] Specifically, a nickel powder production device 1
(hereinafter, simply also referred to as "production device 1")
includes a reaction tank 11 in which a nickel sulfate-amine complex
solution is reacted with hydrogen gas, a depressurization tank 12
that depressurizes the nickel powder slurry produced in the
reaction tank 11 to normal pressure, and discharge piping 13 that
connects the reaction tank 11 and the depressurization tank 12 and
discharges and transfers the nickel powder slurry. Further, this
production device 1 is provided with washing piping 14 that is
connected to the discharge piping 13 and supplies a washing
solution to the discharge piping 13.
[0047] As described above, in the nickel powder production device
1, by providing the washing piping 14 connected to the discharge
piping 13, the washing solution is supplied to the discharge piping
13 so that it is possible to effectively wash the inside of the
discharge piping 13 or a valve and the like provided in the
discharge piping 13, and thus operation failure is prevented to
enable stable operation and improvement in production efficiency
can be achieved.
[Reaction Tank]
[0048] The reaction tank 11 is a place in which the nickel
sulfate-amine complex solution is reacted with hydrogen gas. In
this reaction tank 11, the reaction in which nickel ions in the
nickel sulfate-amine complex solution are reduced to produce nickel
powder, is caused by the supplied hydrogen gas. For example,
hydrogen reduction reaction is caused by adjusting and maintaining
the pressure of the gas phase part inside the reaction tank 11 to a
range of 2.5 MPa to 3.5 MPa by continuous supply of hydrogen
gas.
[0049] The reaction tank 11 is not particularly limited as long as
it is a pressurized reaction tank which can be adjusted to a
predetermined temperature condition and a predetermined pressure
condition and maintained. For example, an autoclave or the like can
be used. The material of the autoclave is not particularly limited,
and for example, an autoclave made of austenitic stainless steel
such as SUS316L or SUS304L can be used. Further, the size thereof
can also be appropriately set depending on a treated amount of the
mixed slurry of a nickel sulfate-amine complex solution as a raw
material and nickel powder as seed crystals, or the like.
[0050] The reaction tank 11 is provided with at least a charging
port 11A in which the nickel sulfate-amine complex solution as a
raw material is charged, a hydrogen gas supply port 11B to which
hydrogen gas for hydrogen reduction is supplied, and an ejection
port 11C that ejects (discharges) a slurry containing nickel powder
produced by hydrogen reduction reaction (nickel powder slurry).
(Charging Port)
[0051] The charging port 11A is connected to charging piping (not
illustrated), and is connected, for example, to a storage tank for
the nickel sulfate-amine complex solution by the charging piping.
In the reaction tank 11, the nickel sulfate-amine complex solution
transferred through the charging piping is charged in the inside
through the charging port 11A. Incidentally, the raw material
charged from the charging port 11A may be the nickel sulfate-amine
complex solution alone or may be a mixed slurry obtained by mixing
nickel powder as seed crystals in the complex solution in
advance.
(Hydrogen Gas Supply Port)
[0052] The hydrogen gas supply port 11B is connected to hydrogen
gas supply piping 21, and is connected, for example, to a hydrogen
gas supply device such as a hydrogen gas cylinder by the hydrogen
gas supply piping 21. In the reaction tank 11, hydrogen gas
supplied through the hydrogen gas supply piping 21 is supplied to
the inside through the hydrogen gas supply port 11B.
[0053] Herein, the hydrogen gas supply piping 21 is, as described
above, piping that is connected to a hydrogen gas cylinder or the
like and is used for supplying hydrogen gas into the reaction tank
11. In this hydrogen gas supply piping 21, a gas supply valve 21a
is provided at a predetermined position and the supply of hydrogen
gas is controlled. Incidentally, the gas supply valve 21a may be an
ON/OFF valve that controls ON (with supply) and OFF (without
supply) of the supply of hydrogen gas, or may be a control valve
that can control the amount of hydrogen gas supplied.
(Ejection Port)
[0054] The ejection port 11C is an ejection port for ejecting and
discharging the nickel powder slurry produced by hydrogen reduction
reaction in the reaction tank 11 from the reaction tank 11. The
discharge piping 13 described later is connected to the ejection
port 11C, and the nickel powder slurry ejected from the ejection
port 11C is discharged and transferred to the depressurization tank
12 through the discharge piping 13.
[Depressurization Tank]
[0055] The depressurization tank 12 is a tank for depressurizing
the nickel powder slurry produced in the reaction tank 11, for
example, to normal pressure. The depressurization tank 12 includes,
for example, a flash tank (flash vessel).
[0056] The depressurization tank 12 is provided with a charging
port 12A for charging the nickel powder slurry discharged from the
reaction tank 11 in the inside at a predetermined position of the
top board thereof. The charging port 12A is connected to the
discharge piping 13 described later, and the nickel powder slurry
from the reaction tank 11 is transferred through the discharge
piping 13 and charged in the inside of the depressurization tank 12
through the charging port 12A.
[Discharge Piping]
[0057] The discharge piping 13 is piping for connecting the
reaction tank 11 and the depressurization tank 12 and discharging
and transferring the nickel powder slurry produced in the reaction
tank 11 to the depressurization tank 12. The nickel powder slurry
discharged from the reaction tank 11 and passing through the
discharge piping 13 is in a state of maintaining a high pressure,
and the nickel powder slurry flows in the discharge piping 13 at a
flow velocity close to a velocity of sound under the high pressure
and is charged in the depressurization tank 12.
[0058] The discharge piping 13 is provided with at least an
ejection valve 13a positioned in the vicinity of the reaction tank
11 side and a flash valve 13b positioned in the vicinity of the
depressurization tank 12.
(Ejection Valve)
[0059] The ejection valve 13a is a control valve for controlling
the amount of the nickel powder slurry ejected from the ejection
port 11C of the reaction tank 11, that is, the amount of the nickel
powder slurry transferred in the discharge piping 13. The ejection
valve 13a may be an ON/OFF valve that controls ON (with transfer)
and OFF (without transfer) of the transfer of the nickel powder
slurry, or may be a control valve that can control the amount of
the nickel powder slurry transferred.
(Flash Valve)
[0060] The flash valve 13b is a control valve for controlling
charging the nickel powder slurry when the nickel powder slurry
transferred through the inside of the discharge piping 13 is
charged in the depressurization tank 12. When the nickel powder
slurry is charged in the depressurization tank 12 by opening and
closing the flash valve 13b while the internal pressure of the
reaction tank 11 is appropriately managed, the continuous operation
can be performed. The flash valve 13b may be an ON/OFF valve that
controls ON (with charge) and OFF (without charge) of the charging
of the nickel powder slurry to the depressurization tank 12, or may
be a control valve that can control the amount of the nickel powder
slurry charged.
[Washing Piping]
[0061] The washing piping 14 is piping that is connected to the
discharge piping 13 and supplies a washing solution to the
discharge piping 13. The washing piping 14 is connected, for
example, to the discharge piping 13 while branching is provided at
a predetermined site of the discharge piping 13 (for example, "P"
in FIG. 2). A connection site on the discharge piping 13 with the
washing piping 14 is not particularly limited, but can be a site in
the vicinity of the ejection valve 13a or in the vicinity of the
flash valve 13b, and can be an intermediate position of the
discharge piping 13 connecting the reaction tank 11 and the
depressurization tank 12.
[0062] The washing piping 14 is provided with a washing solution
supply valve 14a. The washing solution supply valve 14a is provided
in the vicinity of a washing solution tank storing a washing
solution to be supplied to the discharge piping 13 through the
washing piping 14, or the like and controls the supply of the
washing solution. The washing solution supply valve 14a may be an
ON/OFF valve that controls ON (with supply) and OFF (without
supply) of the supply of the washing solution through the washing
piping 14, or may be a control valve that can control the amount of
the washing solution transferred.
[0063] The nickel powder production device 1 according to the
present embodiment includes, as described above, the washing piping
14 connected to the discharge piping 13 for discharging the nickel
powder slurry from the reaction tank 11, and by supplying the
washing solution to the discharge piping 13 through the washing
piping 14, the inside of the discharge piping 13 or a valve (the
ejection valve 13a or the flash valve 13b) and the like provided in
the discharge piping 1 can be washed. According to this, the nickel
powder and other precipitates precipitated to the discharge piping
13, the flash valve 13b, and the like can be washed and removed,
and for example, clogging or trapping of the flash valve 13b can be
effectively prevented.
[0064] The washing solution is not particularly limited, and for
example, water (washing water) or the like can be used. Further,
other than this, drain generated after heat is recovered from steam
generated when pressure is depressurized to normal pressure in the
depressurization tank can be used, and further, a filtrate obtained
by subjecting the recovered nickel powder slurry to solid-liquid
separation by a known method may be reused.
[0065] Further, inert gas supply piping 22 for supplying an inert
gas such as nitrogen gas or argon gas is connected to the washing
piping 14 at a predetermined position. The inert gas such as
nitrogen gas is used for adjusting the internal pressure of the
washing piping 14 and the discharge piping 13 to adjust the
pressure when the washing solution is supplied from the washing
piping 14 to the discharge piping 13. The inert gas supply piping
22 is connected, for example, to a gas cylinder for nitrogen gas or
the like and is provided with a gas supply valve 22a for adjusting
the flow rate of gas at a predetermined position. The pressure of
the inert gas is controlled by the gas supply valve 22a and the
inert gas is supplied to the washing piping 14 through the inert
gas supply piping 22.
[0066] Incidentally, the pressure of the washing solution is not
limited to be controlled by the supply of the inert gas as
described above, but for example, a liquid feeding pump may be
connected to the washing piping 14 and the washing solution in the
washing piping 14 may be pressurized. Further, by the
aforementioned inert gas supply piping 22 being connected directly
to a washing solution storage tank connected with the washing
piping 14, the inert gas may be supplied into the storage tank, so
that the washing solution can be supplied at a predetermined
pressure.
(Supply of Washing Solution Through Washing Piping)
[0067] Herein, it is preferable to supply, to the washing piping
14, the washing solution at a pressure lower than the internal
pressure of the reaction tank 11 by a range of 0.2 MPa to 1.0 MPa.
Further, more preferably, the pressure is set to be lower than the
internal pressure of the reaction tank 11 by a range of 0.5 MPa to
1.0 MPa. Incidentally, the pressure of the washing solution is, as
described above, controlled by the gas supply valve 22a provided in
the washing piping 14. Specifically, since the internal pressure in
the reaction tank 11 is maintained in a range of 2.5 MPa to 3.5 MPa
by the supply of hydrogen gas, the washing solution is supplied
through the washing piping 14 at a pressure lower than the internal
pressure of the reaction tank 11 by a range of 0.2 MPa to 1.0 MPa,
for example, at a pressure of 2.0 MPa to 2.5 MPa.
[0068] When a difference between the supply pressure of the washing
solution and the internal pressure of the reaction tank 11 is less
than 0.2 MPa, the removal force by the flow velocity at the time of
supplying the washing solution becomes small and thus there is
possibility that sufficient washing cannot be performed. On the
other hand, even when the difference with the internal pressure of
the reaction tank 11 is larger than 1.0 MPa, the washing effect is
not further improved, and instead, there is possibility that piping
and valves are worn out or damaged by the nickel powder removed by
washing, or the like.
Examples
[0069] Hereinafter, the present invention will be described in more
detail by means of Examples of the present invention, but the
present invention is not limited to the following Examples at
all.
Example 1
[0070] Nickel powder was produced using the device as schematically
illustrated in FIG. 2. That is, an autoclave made of austenitic
stainless steel such as SUS316L or SUS304L with a capacity of 200 L
was used as a reaction tank, and hydrogen gas was continuously
supplied to a nickel sulfate-amine complex solution to cause
hydrogen reduction reaction. Further, a flash tank with a capacity
of 1000 L was used as a depressurization tank, and a slurry of the
nickel powder produced in the reaction tank was charged in the
flash tank and was depressurized to atmospheric pressure. Then, the
reaction tank and the depressurization tank were connected by
discharge piping with an inner diameter of 10 mm. Incidentally, an
ejection valve was provided at an ejection port of the reaction
tank, a flash valve for controlling the charging of the nickel
powder slurry into the depressurization tank was provided at a
ceiling part of the depressurization tank, and charging control was
performed by opening and closing the valve.
[0071] Further, in the production device, washing piping was
connected while branching was provided in the middle of the
discharge piping, and a washing solution was enabled to be supplied
to the discharge piping through the washing piping. Incidentally,
the washing piping was connected while branching was provided at
the side close to the reaction tank in the discharge piping.
Further, piping for industrial water was connected to the washing
piping, and the industrial water as the washing solution was
supplied under the supply control by a washing solution supply
valve. Furthermore, supply piping supplying nitrogen gas as an
inert gas was connected to the washing piping, and the nitrogen gas
was enabled to be supplied under the supply control by a gas supply
valve.
[0072] The nickel sulfate-amine complex solution with a nickel
concentration of 82.5 g/L was supplied at a flow rate of 1.0 L/min
to the reaction tank by using such a production device. Further, a
slurry containing 33 g/L of nickel powder with a diameter of 75
.mu.m or less as seed crystals was supplied at a flow rate of 0.5
L/min.
[0073] Further, the internal temperature of the reaction tank was
maintained at 185.degree. C., and the pressure inside the reaction
tank was adjusted to a range of 2.5 MPa to 3.5 MPa by blowing
hydrogen gas from a cylinder. Incidentally, in order to maintain
the amount of the solution in the reaction tank to be 90 L, the
flash valve attached to the top part of the depressurization tank
was intermittently opened and closed to extract the nickel powder
slurry into the depressurization tank through the discharge
piping.
[0074] After the nickel powder was extracted, the ejection valve of
the reaction tank and the flash valve were sequentially closed in
this order. Next, the washing solution supply valve Provided in the
washing piping was opened to supply 4 L of washing solution
(industrial water) into the discharge piping through the washing
piping, and then the washing solution supply valve was closed.
Incidentally, 1 to 2 L space was allowed to remain inside the
washing piping and the discharge piping. Then, the gas supply valve
was opened to adjust the internal pressure of the washing piping
and the discharge piping to a range of 2.0 MPa to 2.5 MPa that is
lower than the internal pressure of the reaction tank by 0.5 MPa to
1.0 MPa, and the washing solution was supplied to the discharge
piping at such a pressure.
[0075] The discharge piping and the flash valve were washed by
opening the flash valve under the supply of the washing solution
through the washing piping. After the completion of washing, the
ejection valve of the reaction tank and the flash valve were
opened, and discharging of the nickel powder slurry from the
reaction tank to the depressurization tank was repeated.
[0076] Although the operation as described above was continued for
6 hours, abrasion, or adhering or trapping of the nickel powder or
the like in the flash valve and the discharge piping did not occur,
and it was possible to stably perform extraction of the nickel
powder slurry from the reaction tank to the depressurization tank
without any trouble.
Example 2
[0077] The operation was performed using the same production device
as in Example 1, except that the washing piping was connected to a
350 L washing solution storage tank, and nitrogen gas supply piping
was connected directly to the washing solution storage tank to
enable nitrogen gas to be supplied.
[0078] As the washing solution, 300 L of filtrate obtained by
subjecting the nickel powder slurry recovered from the
depressurization tank by the operation in Example 1 to solid-liquid
separation using Nutsche was used. Incidentally, the filtrate was
stored in the washing solution storage tank and used as the washing
solution. Further, nitrogen gas was supplied to the washing
solution storage tank to adjust the internal pressure of the
washing solution storage tank to a range of 2.0 MPa to 2.5 MPa, the
washing solution supply valve was controlled such that 4 L of the
washing solution was ejected at one time, and the washing solution
was supplied to the discharge piping through the washing
piping.
[0079] Although the operation as described above was continued for
7 hours, abrasion, or adhering or trapping of the nickel powder or
the like in the flash valve and the discharge piping did not occur,
and it was possible to stably perform extraction of the nickel
powder slurry from the reaction tank to the depressurization tank
without any trouble.
Comparative Example 1
[0080] The operation was performed using the same production device
as in Example 1, except that the washing piping was not provided.
That is, the operation was performed using the production device
not including the mechanism of supplying the washing solution to
the discharge piping at a predetermined pressure.
[0081] Although the operation was performed for 6 hours under the
same condition as in Example 1, after 1 hour from the operation
start, opening and closing of the flash valve were not able to be
controlled, an excessive amount of the nickel powder slurry was
discharged and transferred from the reaction tank to the
depressurization tank, so that the amount of the solution in the
reaction tank was not able to be maintained to 90 L and the
operation was stopped.
[0082] After the operation stop, when the flash valve was observed,
the nickel precipitate or fine nickel powder was precipitated or
trapped in the valve.
EXPLANATION OF REFERENCE NUMERALS
[0083] 1 NICKEL POWDER PRODUCTION DEVICE [0084] 11 REACTION TANK
[0085] 11A CHARGING PORT [0086] 11B HYDROGEN GAS SUPPLY PORT [0087]
11C EJECTION PORT [0088] 12 DEPRESSURIZATION TANK [0089] 12A
CHARGING PORT [0090] 13 DISCHARGE PIPING [0091] 13a EJECTION VALVE
[0092] 13b FLASH VALVE [0093] 14 WASHING PIPING [0094] 14a WASHING
SOLUTION SUPPLY VALVE [0095] 21 HYDROGEN GAS SUPPLY PIPING [0096]
21a GAS SUPPLY VALVE [0097] 22 INERT GAS SUPPLY PIPING [0098] 22a
GAS SUPPLY VALVE
* * * * *