JP4128305B2 - Metal powder production equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for producing metal powder, specifically, conductive paste fillers used for electronic parts, Ti bonding materials, and metals such as Ni, Cu, and Ag suitable for various uses such as catalysts. The present invention relates to an apparatus suitable for producing ultrafine powder.
[0002]
[Prior art]
Among the Ni, Cu, and Ag mentioned above, Ni (hereinafter, referred to as nickel) powder is attracting attention as an internal electrode for multilayer ceramic capacitors because it is less expensive than conventional Pd powder. Above all, nickel powder manufactured by a dry method such as hydrogen reduction of metal chloride is suitable for mass production because its manufacturing process is simpler than that of a wet method. Of these nickel powders, the particle size of 1 μm or less, of course, and the particle size of 0.5 μm or less are required due to the demands for reducing the thickness and reducing the resistance of internal electrodes due to the downsizing of multilayer ceramic capacitors and the increase in capacity. There is a demand for nickel ultrafine powder.
[0003]
As a conventional apparatus for producing the above-mentioned nickel ultrafine powder, nickel chloride gas is generated by heating and evaporating nickel chloride in an evaporation section, and this nickel chloride gas is used as a hydrogen gas (reducing gas) atmosphere. There are some which are transferred to a reaction section through a transfer pipe and cause a gas phase chemical reaction with nickel chloride gas and hydrogen gas to generate ultrafine nickel powder.
[0004]
[Problems to be solved by the invention]
In the above conventional manufacturing apparatus, a heat loss occurs in which the temperature of the nickel chloride gas is lowered while being transferred from the evaporation section to the reaction section through the transfer pipe. For this reason, the nickel chloride gas is cooled and the nickel chloride is transferred into the transfer pipe. There was a risk of precipitation. In order to solve this problem, the transfer pipe is heated. However, the provision of the heating means increases the energy consumption and increases the complexity and size of the apparatus.
[0005]
Further, since nickel chloride is used as a starting material, it is essentially difficult to stably generate nickel chloride gas, the partial pressure of nickel chloride gas varies, and the particle size of the metal powder to be generated is not stable. In addition, since nickel chloride has crystal water, dehydration is required before use, and when the dehydration is insufficient, the oxygen concentration in the metal powder to be generated increases.
[0006]
The metal powder manufacturing apparatus of the present invention has been made in view of the above circumstances, and has the following purposes.
1. The energy required for heating is reduced by suppressing the heat loss of the metal chloride gas during transfer.
2. Simplify and miniaturize equipment.
3. The particle size can be easily controlled with high accuracy, and a high-quality metal powder having a narrow particle size distribution can be obtained stably.
[0007]
[Means for Solving the Problems]
The metal powder production apparatus of the present invention is an apparatus for producing metal powder by reducing metal chloride, filled with a metal raw material, and contacting the metal raw material with chlorine gas to continuously supply the metal chloride gas. A chloride part to be generated automatically, a reaction part which is supplied with a metal chloride gas generated in the chloride part and causes a gas phase chemical reaction with the metal chloride gas and a reducing gas to obtain metal powder, and a chloride part A metal chloride gas that is provided with a metal chloride gas inlet at one end thereof facing the reaction portion and extending in the chloride portion, and that supplies the metal chloride gas introduced from the inlet to the reaction portion And a supply pipe.
[0008]
According to the above configuration, the metal chloride gas generated in the chlorination section is introduced into the metal chloride gas supply pipe from the metal chloride gas inlet and supplied to the reaction section through the supply pipe. And it contacts with reducing gas in a reaction part, raise | generates a gas phase chemical reaction, and produces | generates metal powder. In the present invention, an operation mode in which a carrier gas is introduced into a metal chloride gas supply pipe and the metal chloride gas is supplied to the reaction section together with the carrier gas can be employed.
[0009]
According to the present invention, since the metal chloride gas supply pipe passes through the chloride portion, the metal chloride gas passing through the inside is heated by the chloride portion and supplied to the reaction portion as it is. Therefore, first, the precipitation of nickel chloride in the metal chloride gas supply pipe is prevented. Further, heat loss does not occur in the metal chloride gas being transferred to the reaction section, and it is not necessary to heat the metal chloride gas, so that energy consumption is reduced. Furthermore, simplification and miniaturization of the apparatus can be achieved.
[0010]
Further, the amount of metal chloride gas generated in the chlorination part can be made constant by the supply amount of chlorine gas when the metal material is brought into contact with chlorine gas. Therefore, the amount of metal chloride gas supplied to the reaction section and the partial pressure of the metal chloride gas in the reaction section can be controlled easily and with high accuracy, and the particle size of the metal powder produced in the reaction section must be controlled accurately. Can do. As a result, a high-quality metal powder having a small particle size and a narrow particle size distribution can be stably obtained.
[0011]
In the present invention, it is preferable to dispose the chloride portion adjacent to the reaction portion. With this configuration, the transfer distance of the metal chloride gas supply pipe, that is, the metal chloride gas is further shortened, and the effects of reducing the energy consumption and simplifying and miniaturizing the apparatus are further promoted.
[0012]
In the present invention, the metal chloride gas supply pipe is preferably provided with a negative pressure generating means for sucking the metal chloride gas from the metal chloride gas inlet into the supply pipe. Examples of the negative pressure generating means include a venturi mechanism that generates a negative pressure by increasing the gas flow rate.
[0013]
According to this configuration, for example, when the carrier gas is circulated through the metal chloride gas supply pipe as described above, the carrier gas and the metal chloride gas are well mixed and a uniform diluted state can be obtained.
[0014]
The amount of metal chloride gas introduced into the metal chloride gas supply pipe and the dilution rate of the metal chloride gas with the carrier gas are negative when the amount of metal chloride gas generated and the carrier gas flow rate are constant. It depends on the size. Therefore, by using the magnitude of this negative pressure as a control factor, the supply amount of the metal chloride gas to the reaction part and the partial pressure of the metal chloride gas in the reaction part can be controlled more accurately. From the viewpoint of performing such control more precisely, it is more preferable to adopt a configuration in which the magnitude of the negative pressure generated by the negative pressure generating means can be adjusted.
[0015]
Now, the metal powder that can be produced by the metal powder production apparatus of the present invention is Cu, Ag, etc. in addition to the above nickel, and these powders are conductive paste filler, Ti material bonding material, further catalyst, etc. Suitable for various applications. Among these, the present invention is particularly suitable for producing nickel ultrafine powder.
[0016]
As the carrier gas to be circulated in the metal chloride gas supply pipe, an inert gas such as argon gas or nitrogen gas is preferably used. However, a reducing gas may be mixed in the carrier gas, and further, the reducing gas Can also be used as a carrier gas. Further, as the reducing gas, a reducing gas such as hydrogen gas or hydrogen sulfide gas can be used, but hydrogen gas is preferable in view of the influence on the generated metal powder.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[1] Configuration of Manufacturing Apparatus FIG. 1 shows a manufacturing apparatus for metal powder according to an embodiment. The apparatus is mainly composed of a cylindrical vertical reduction furnace 1, and the inside of the reduction furnace 1 is divided into an upper chlorination chamber (chlorination part) 1A and a lower reaction chamber (reaction part) 1B by a partition 2. Yes. The chlorination chamber 1A and the reaction chamber 1B are heated to predetermined temperatures by heating means 3A and 3B arranged around the reduction furnace 1, respectively. A reducing gas supply pipe 4a for supplying a reducing gas to the reaction chamber 1B is connected to the upper part of the furnace wall constituting the reaction chamber 1B. A recovery tube 4b for recovering the generated metal powder is provided at the lower end of the reaction chamber 1B.
[0018]
A metal chloride gas supply pipe (hereinafter simply referred to as a supply pipe) 5 for supplying metal chloride gas generated in the chloride chamber 1A to the reaction chamber 1B is disposed on the upper portion of the reduction furnace 1. The supply pipe 5 extends along the axis of the reduction furnace 1 from the top of the reduction furnace 1 through the chlorination chamber 1A to the reaction chamber 1B, and its lower end faces the upper portion of the reaction chamber 1B. Carrier gas may flow from outside the reduction furnace 1 to the supply pipe 5, and the supply pipe 5 is provided with a valve 6 that adjusts or shuts off the flow rate of the carrier gas. The lower end portion of the supply pipe 5 is configured as a nozzle 5a that ejects carrier gas into the reaction chamber 1B. Furthermore, a metal chloride gas inlet (hereinafter simply referred to as an inlet) 7 is provided in the circumferential direction in the portion extending to the vapor layer filled with the metal chloride gas in the chloride chamber 1A of the supply pipe 5. They are spaced at regular intervals.
[0019]
At the bottom of the chlorination chamber 1A, a perforated plate 8 is horizontally stretched apart from the partition 2, and a metal raw material is deposited on the perforated plate 8. The perforated plate 8 is made of a material that is not affected by chlorine gas. For example, a ceramic plate is preferably used. A chlorine gas supply pipe 9 for supplying chlorine gas to the space between the partition 2 and the perforated plate 8 is connected to the bottom of the furnace wall constituting the chlorination chamber 1A.
[0020]
[2] Production Example of Nickel Ultrafine Powder Next, a specific example of producing nickel ultrafine powder using the above metal powder production apparatus will be described.
First, solid metallic nickel (metal raw material) is charged and deposited on the porous plate 8 of the chlorination chamber 1A. The form of metallic nickel is not particularly limited, but from the viewpoint of contact efficiency and prevention of an increase in pressure loss, a granular shape with a particle size of 5 to 20 mm, a lump shape, a plate shape, or the like is preferable, and the purity is approximately 99.5% or more. preferable. Next, the chlorination chamber 1A is heated by the heating means 3A, and chlorine gas is supplied from the chlorine gas supply pipe 9 to the chlorination chamber 1A. When the chlorine gas comes into contact with the metallic nickel, the chlorine gas is converted into nickel chloride gas (metal chloride gas).
[0021]
The heating temperature of the chlorination chamber 1A is set to 800 ° C. or higher and 1483 ° C. or lower, which is the melting point of nickel, in order to sufficiently advance the reaction between chlorine gas and metallic nickel. Considering the durability and reaction rate of the reduction furnace 1, the range of 900 to 1100 ° C. is preferable for practical use. The layer height and density of metallic nickel on the porous plate 8 are sufficiently converted to nickel chloride gas based on the supply rate of chlorine gas, the heating temperature of the chlorination chamber 1A, the operating time, the shape of metallic nickel, and the like. The range is set as appropriate.
[0022]
As described above, nickel chloride gas is continuously generated in the chlorination chamber 1A. On the other hand, the reaction chamber 1B is heated to a predetermined reduction temperature by the heating means 3B, and further, an inert gas (argon gas or nitrogen gas) is supplied as a carrier gas to the supply pipe 5 and supplied to the reaction chamber 1B. Is supplied to the reaction chamber 1B by flowing through the reducing gas supply pipe 4a. The reduction temperature is preferably about 900 to 1100 ° C.
[0023]
The nickel chloride gas generated in the chlorination chamber 1A is introduced in a state of being sucked into the supply pipe 5 from the introduction port 7. The nickel chloride gas sucked and introduced into the supply pipe 5 is mixed with the carrier gas and discharged from the nozzle 5a to the reaction chamber 1B. In the reaction chamber 1B, nickel chloride gas diluted with a carrier gas comes into contact with hydrogen gas to cause a gas phase chemical reaction, thereby generating ultrafine nickel powder.
[0024]
The produced nickel ultrafine powder is cooled in the lower part of the reaction chamber 1B together with an inert gas, hydrochloric acid gas by-produced by a gas phase chemical reaction, and the like, and then recovered from the recovery tube 4b. Then, it is separated and recovered from the mixed gas and further washed to obtain a product.
[0025]
According to this embodiment, since the supply pipe 5 penetrates the chlorination chamber 1A, the nickel chloride gas passing through the supply pipe 5 is heated by the chlorination chamber 1A and supplied to the reaction chamber 1B as it is. Therefore, first, the precipitation of nickel chloride in the supply pipe 5 is prevented. Further, no heat loss occurs in the nickel chloride gas being transferred to the reaction chamber 1B, and it is not necessary to heat the nickel chloride gas separately, so that energy consumption is reduced. Further, since the supply pipe 5 penetrates the chlorination chamber 1A and the chlorination chamber 1A is disposed adjacent to the reaction chamber 1B, the transfer distance of the supply pipe 5, that is, nickel chloride gas, is short. Reduction, simplification and miniaturization of the apparatus can be achieved.
[0026]
Further, the amount of nickel chloride gas generated in the chlorination chamber 1A can be made constant by the amount of chlorine gas supplied when the chlorine gas is brought into contact with the metal raw material. Therefore, the amount of nickel chloride gas supplied to the reaction chamber 1B and the partial pressure of the nickel chloride gas in the reaction chamber 1B can be easily and accurately controlled, and the particle diameter of the ultrafine nickel powder generated in the reaction chamber 1B is accurately controlled. can do. As a result, high-quality nickel ultrafine powder having a small particle size and a narrow particle size distribution can be stably obtained.
[0027]
In the above embodiment, an inert gas is used as the carrier gas. However, a reducing gas (hydrogen gas in the above specific example) or chlorine gas may be mixed in the carrier gas, and further, the reducing gas may be mixed. It can also be used as a carrier gas. Further, it is possible to adopt an operation mode in which the carrier gas is not circulated through the supply pipe 5 and the nickel chloride gas generated in the chlorination chamber 1A is supplied as it is to the reaction chamber 1B without being diluted. In this case, the valve 6 is closed, and nickel chloride gas is introduced into the supply pipe 5 from the introduction port 7 by the increase in the internal pressure of the chlorination chamber 1A. The supply amount of nickel chloride gas to the reaction chamber 1B is adjusted by the supply amount of chlorine gas to the chloride chamber 1A.
[0028]
[3] Negative pressure generating means (Venturi mechanism)
By the way, in the present invention, the supply pipe 5 can be provided with a negative pressure generating means for sucking a metal chloride gas (nickel chloride gas in the specific example) from the introduction port 7 into the supply pipe 5. Examples of the negative pressure generating means include a venturi mechanism that generates a negative pressure by increasing a gas flow rate. Hereinafter, such a venturi mechanism will be exemplified.
[0029]
A. As shown in FIG. 2A, a bulging portion 5b is integrally formed over the entire circumference on the inner peripheral portion corresponding to the introduction port 7 of the supply pipe 5, and the bulging portion 5b constitutes a venturi mechanism. The bulging portion 5b is formed in an arc shape so that the thickness of the longitudinal section gradually increases from the upper and lower ends toward the axial central portion, and a plurality of inlets 7 are provided in the circumferential direction at the thickest portion. Are provided at equal intervals.
[0030]
B. As shown in FIG. 2B, a venturi mechanism is constituted by a funnel-shaped throttle member 10 provided on the upstream side of the introduction port 7.
C. As shown in FIG. 2 (c), the nozzle 5 a of the supply pipe 5 is reduced in diameter and throttled, and the introduction port 7 is communicated with the inner pipe 11 passing through the supply pipe 5 to constitute a venturi mechanism.
D. As shown in FIG. 2D, the throttle valve 12 forms a venturi mechanism.
[0031]
By providing the venturi mechanism in the supply pipe 5 as described above, a negative pressure is generated when the carrier gas flowing through the supply pipe 5 toward the reaction chamber 1B passes through the venturi mechanism. The metal chloride gas generated in the chlorination chamber 1A is introduced into the supply pipe 5 from the introduction port 7 using the negative pressure generated by the venturi mechanism. Thereby, carrier gas and metal chloride gas are mixed well, and a uniform dilution state can be obtained.
[0032]
The amount of metal chloride gas introduced into the supply pipe 5 and the dilution rate of the metal chloride gas by the carrier gas are generated by the venturi mechanism when the amount of metal chloride gas generated and the carrier gas flow rate are constant. It depends on the size of the negative pressure. Therefore, by using the magnitude of the negative pressure as a control factor, the supply amount of the metal chloride gas to the reaction chamber 1B and the partial pressure of the metal chloride gas in the reaction chamber 1B can be controlled more accurately. In addition, it is possible to produce an ultrafine metal powder having a particle size of, for example, 0.5 μm or less. The magnitude of the negative pressure generated by the venturi mechanism as described above can be controlled by the narrow state in the supply pipe 5.
[0033]
Furthermore, according to the venturi mechanism constituted by the throttle valve 12 shown in FIG. 2 (d), the magnitude of the negative pressure, that is, the supply amount of the metal chloride gas to the reaction chamber 1B, depending on the opening degree of the throttle valve 12. Can be controlled arbitrarily and easily. Therefore, the particle size control of the produced metal powder can be performed more precisely.
[0034]
【Example】
Next, the Example of this invention which manufactured the nickel ultrafine powder using the manufacturing apparatus shown in FIG. 1 is described.
On the porous plate 8 of the chlorination chamber 1A, 15 kg of solid metal nickel having an average particle diameter of 10 mm as a starting material was charged and deposited. The chlorination chamber 1A was heated to 1100 ° C. by the heating means 3A, chlorine gas was supplied from the chlorine gas supply pipe 9 to the chlorination chamber 1A at a flow rate of 4 Nl / min, and solid metal nickel was chlorinated to generate nickel chloride gas. On the other hand, while flowing argon gas through the supply pipe 5 at a flow rate of 2 Nl / min and feeding it to the reaction chamber 1B, the reaction chamber 1B was heated to 950 ° C. by the heating means 3B. This operation was continued for 60 minutes, and nickel ultrafine powder was continuously generated in the reaction chamber 1B.
[0035]
Next, nitrogen gas and hydrochloric acid vapor by-produced by the reaction and nickel ultrafine powder were led from the collection pipe 4b to the oil scrubber, and the nickel ultrafine powder was separated and recovered. Thereafter, the recovered ultrafine nickel powder was washed with xylene and dried to obtain ultrafine nickel powder. The nickel ultrafine powder had an average particle size of 0.3 μm and was a spherical particle having a substantially uniform shape, and was extremely high quality.
[0036]
【The invention's effect】
As described above, the present invention is characterized in that the metal chloride gas supply pipe for supplying the metal chloride gas generated in the chloride section to the reaction section penetrates the chloride section. There is an effect.
1. Since the metal chloride gas is heated in the chlorination section, precipitation of the metal chloride in the metal chloride gas supply pipe is prevented.
2. There is no heat loss in the metal chloride gas being transferred to the reaction section, and there is no need to heat it, so energy consumption is reduced.
3. The apparatus can be simplified and miniaturized.
4). Since metal chloride gas is generated by bringing chlorine gas into contact with the metal raw material, metal chloride gas can be stably generated, and high-quality metal powder with a narrow particle size distribution can be stably obtained. .
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an apparatus for producing metal powder according to an embodiment of the present invention.
FIGS. 2A to 2D are longitudinal sectional views showing various examples of a venturi mechanism according to the present invention.
[Explanation of symbols]
1 ... Reduction furnace 1A ... Chlorination chamber (chlorination section)
1B ... Reaction chamber (reaction part)
5 ... Metal chloride gas supply pipe 5b ... Swelling part (Venturi mechanism: negative pressure generating means)
7 ... Metal chloride gas inlet 10 ... Throttle member (Venturi mechanism: negative pressure generating means)
11 ... Inner pipe (Venturi mechanism: Negative pressure generating means)
12 ... Throttle valve (Venturi mechanism: negative pressure generating means)

Claims (5)

An apparatus for producing metal powder by reducing metal chloride,
A chlorination section that is filled with a metal raw material and in which a chlorine gas is brought into contact with the metal raw material to continuously generate a metal chloride gas;
A metal chloride gas generated in the chlorination part is supplied, and a reaction part for obtaining a metal powder by causing a gas phase chemical reaction between the metal chloride gas and a reducing gas;
One end opening through the chloride portion faces the reaction portion, and a metal chloride gas inlet is provided in an extended portion in the chloride portion, and the metal chloride gas introduced from the inlet is supplied to the reaction portion. An apparatus for producing metal powder, comprising: a metal chloride gas supply pipe to be supplied. The apparatus for producing metal powder according to claim 1, wherein the chlorination part is disposed adjacent to the reaction part. 2. The metal chloride gas supply pipe is provided with negative pressure generating means for sucking the metal chloride gas from the metal chloride gas inlet into the supply pipe. 2. The apparatus for producing metal powder according to 2. 4. The metal powder manufacturing apparatus according to claim 3, wherein the negative pressure generated by the negative pressure generating means is adjustable. 5. The metal chloride gas introduced into the metal chloride gas supply pipe is supplied to the reaction section together with a carrier gas circulated through the metal chloride gas supply pipe. An apparatus for producing metal powder according to 1.

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