JPH1068007A - Production of fine metallic grain and atomizing device for producing fine metallic grain - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently producing uniform fine metallic grains of high quality at a high yield and at a low cost at the time of producing fine metallic grains and to provide an atomizing device used as a device for producing fine metallic grains. SOLUTION: This method for producing fine metallic grains is the one in which a metallic ion soln. is atomized by a gas fed from a gas feed opening part 72 disposed in the vicinity of a metallic ion soln. feed opening part 71, which is subjected to reducing treatment in reducing flame, and furthermore, a gas for protection is fed thereto to protect the metallic ion soln. feed opening part 71. The atomizing device 1 has a metallic ion soln. feed opening part, a gas feed opening part 72 for atomizing a metallic ion soln. and a gas feed opening part 73 for protection for protecting the metallic ion soln. feed opening part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for producing fine metal particles. The method and apparatus for producing fine metal particles according to the present invention can be applied to both heavy metals and light metals as long as they can be ionized. Further, the present invention is applicable to metal fine particles ranging from ultrafine particles that behave as colloids in a solvent to relatively large particles such as metal mud and powder.

[0002] Metal fine particles are useful as a catalyst because of their large surface area. In particular, it has excellent oxidation-reduction ability, and is attracting attention as a catalyst for removing and purifying various harmful gases. Some combinations of metals can also be powerful magnetic materials. Other applications include various sensors and molecular wiring.

[0003]

2. Description of the Related Art Methods for producing colloidal metal fine particles are roughly classified into an arc method in which an electrode is provided in a metal ion solution to cause electrophoresis by a high voltage to produce a metal colloid, There are two known combustion methods of obtaining a metal colloid by supplying metal into a flame and reducing metal ions. As a method for producing colloidal metal fine particles by a combustion method, a method in which hydrogen is blown into a metal ion solution container to atomize the metal ion solution and burn the atomized metal ions (Japanese Patent Publication No. 28-1999), a metal ion solution And hydrogen are mixed and atomized and burned (Japanese Patent Publication No. 43801) A method for reducing metal ions (JP-A-7-173511) has been proposed.

[0004] In each of these methods, a metal ion solution as a raw material is sprayed into the atmosphere under pressure to atomize the solution. The particle size of the metal ion solution particles generated at this time is determined by the difference between the pressure at which the metal ion solution is delivered and the atmospheric pressure, and the opening diameter of the delivery port. That is, in the prior art, the dominant factors that determine the particle size of the metal ion solution particles are the pressure difference between the metal ion solution delivery pressure and the atmospheric pressure and the opening diameter of the metal ion delivery unit. In order to generate ultrafine metal particles having a small particle size, it is necessary to maintain a high delivery pressure of the metal ion solution. For this purpose, a high pressure is applied to the circuit from the metal ion solution container to the delivery port, and it is difficult to stably operate for a long time.

[0005] Further, since the atomization state is also affected by the atmospheric pressure, the surrounding pressure changes due to convection due to the combustion flame, and the spray state is liable to change, so that the target metal particles have a uniform particle diameter. Is difficult. Further, since the metal ion solution delivery pressure is set so as to optimize the atomization state of the metal ion solution, the particle size and delivery amount of the atomized particles cannot be independently controlled.

In addition, since the metal ion solution delivery section is located immediately above the combustion section, the metal ion solution delivery section is damaged or deformed due to overheating, and solid matter adheres to the metal ion solution delivery port due to convection of reaction products. This significantly reduces the durability of the apparatus and also changes the shape of the metal ion solution sending section, which contributes to non-uniformity of the generated metal fine particles. That is, in these methods, the hydrogen flame rises upward, and the outlet of the metal ion solution is surrounded by the hydrogen flame. For this reason, solid matter adheres to the metal ion solution delivery port, and the matter gradually grows. Therefore, there is a problem that the amount of the metal ion solution delivered decreases with the elapse of the operation time and the particle size of the generated metal fine particles also changes. When solid matter adheres to the metal ion solution delivery port, it is necessary to replace the atomizer itself after a certain period of time. This significantly impairs the efficiency of metal fine particle production.
In addition, there is a risk of explosion, and the rise of combustion flame
Increased risk of burns to workers.

As described above, according to the conventional method for producing metal fine particles, it is difficult to obtain uniform metal fine particles, and the recovery rate of metal fine particles is low.
Problems such as clogging of the metal ion solution delivery port easily occur and there is a danger of explosion, low efficiency of metal fine particle production, and burns to workers due to rising combustion flame are recognized.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and provides a method for efficiently producing uniform high-quality metal fine particles at low cost and an atomizing apparatus used in a metal fine particle producing apparatus. It is intended to provide.

[0009]

The gist of the present invention is to provide a method for producing metal fine particles, wherein metal ions are supplied from a metal ion solution supply opening and the supplied metal ions are supplied to the metal ion solution supply opening. The method is a method for producing fine metal particles, wherein the fine particles are atomized by a gas supplied from a gas supply opening provided in the vicinity of the portion, and the atomized metal ions are reduced in a reducing flame to generate fine metal particles.

In the method for producing metal fine particles, when the metal ions are supplied from a metal ion solution supply opening and reduced in a reducing flame to produce metal fine particles, the metal ion solution supply opening is connected to a combustion flame. A method for producing metal fine particles, characterized by blowing a gas to protect the fine particles from metal.

In the method for producing metal fine particles, metal ions are supplied from a metal ion solution supply opening, and the supplied metal ions are supplied to a gas supply opening provided near the metal ion solution supply opening. Atomizing with the gas supplied from the gas, and when the atomized metal ions are reduced in the reducing flame to generate metal fine particles, the gas is blown to protect the metal ion solution supply opening from the combustion flame. This is a method for producing metal fine particles.

Further, in an apparatus for producing metal fine particles, a metal ion solution supply opening for supplying metal ions,
And a gas supply opening provided in the vicinity of the metal ion solution supply opening for supplying a gas for atomizing the metal ion solution.

In an apparatus for manufacturing metal fine particles, a metal ion solution supply opening for supplying metal ions,
And a protective gas supply opening for protecting the metal ion solution supply opening from a combustion flame.

In the apparatus for producing metal fine particles, a metal ion solution supply opening for supplying metal ions,
A gas supply opening provided in the vicinity of the metal ion solution supply opening for supplying gas for atomizing the metal ion solution, and a protection gas supply for protecting the metal ion solution supply opening from combustion flame An atomizing device for producing fine metal particles, comprising an opening.

The atomizing device of the present invention is provided with an opening for gas supply for atomization near the opening for supplying the metal ion solution. With this atomization mechanism, the atomization state of the metal ion solution is determined by the pressure difference between the metal ion solution supply opening and the gas supply opening, and is hardly affected by the surrounding atmosphere after atomization. Therefore, it becomes easy to stably maintain a desired particle diameter. Further, since atomization of the metal ion solution is realized by adjusting the pressures of both openings, it is not necessary to use a particularly high pressure, and it is easy to stably operate the apparatus. Further, the pressure of both openings can be easily adjusted, and the amount of the metal ion solution to be delivered can be adjusted within the range of the pressure adjusting function while maintaining the atomized state in an optimum state.

Next, a protective gas is supplied to protect the metal ion solution supply opening, so that the metal ion solution supply opening is protected from the burning flame to prevent deformation due to overheating, and at the same time to prevent the reaction product metal Adhesion to the ion solution supply opening can be reduced. Therefore, it is possible to maintain the optimal atomization state at the start of operation without adjustment for a long time. Thereby, it is easy to ensure the uniformity of the generated metal fine particles.

Further, in the atomization apparatus of the present invention, an opening for gas supply for atomization is provided in the vicinity of the opening for supplying the metal ion solution, and in addition, the opening for supplying the metal ion solution is protected. Therefore, by providing the protective gas supply opening for supplying the protective gas, a more efficient device can be provided.

The atomizing device is a key when producing fine metal particles. The most important role of the atomizer is to eject the metal ion solution in a uniform and fine mist. The metal ion solution is supplied to the metal ion solution supply opening by pumping by a pressurized gas or a pump, and is sent out. A gas is supplied from the gas supply opening to the vicinity of the metal ion solution supply opening, and the delivered metal ion solution is formed into a uniform fine mist. Note that a needle valve may be used to adjust the supply amount of the metal ion solution.

The atomized metal ion solution is guided into a combustion flame on a separately provided combustion burner. The metal ions are reduced in the combustion flame into metal fine particles, and the fine particles are collected in a water tank provided below the atomizing device. It is advisable to stir the water in the water tank to improve the recovery efficiency. For the combustion, a reducing flame is used. As a reducing flame,
Usually, a hydrogen flame is used, but not limited to this.
Other examples of the reducing flame include flames such as carbon monoxide gas and methane gas.

In the conventional method, the combustion flame is lighter than air and necessarily rises to the metal ion solution supply opening. For this reason, solids adhere to the metal ion solution supply opening, which gradually grows until the metal ion solution supply opening is closed. In addition, the rise of the flame may cause the metal ion solution supply opening to be deformed due to overheating, or may cause a burn to the operator. In the present invention, in order to solve these problems, a protective gas supply opening is provided, from which a protective gas is supplied to protect the metal ion solution supply opening. By supplying the protective gas, the rise of the combustion flame is reduced, and there is also a direct cooling effect by the supply of the protective gas itself, thereby suppressing the rise in the temperature near the metal ion solution supply opening. As a result, the adhesion of solids to the metal ion solution supply opening is significantly reduced. Furthermore, the deformation of the metal ion solution supply opening can be reduced, and the risk of burns to the operator can be reduced.

According to the present invention, when producing fine metal particles from a metal ion solution, the metal ion solution is atomized by a gas supplied from a gas supply opening provided near the metal ion solution supply opening, and this is reduced. A method for producing metal fine particles, characterized by performing a reduction treatment in a flame, and further comprising, in producing metal fine particles from a metal ion solution, a metal ion solution supply opening when reducing the metal ion solution in a reducing flame. A method for producing metal fine particles, characterized in that a protective gas is supplied to a portion to protect a metal ion solution supply opening. Then, the metal ion solution is atomized by the gas supplied from the gas supply opening provided near the metal ion solution supply opening, and when the metal ion solution is subjected to reduction treatment in a reducing flame, the metal ion solution is supplied to the metal ion solution supply opening. A method for producing metal fine particles, wherein a protective gas is supplied to protect a metal ion solution supply opening.

Further, in order to realize the present invention, an atomizing device is used. The atomization device of the present invention has a metal ion solution supply opening and a gas supply opening near the vicinity thereof for supplying gas for atomizing the metal ion solution.
Further, it may have a metal ion solution supply opening and a protection gas supply opening for supplying a protection gas for protecting the metal ion solution supply opening. Further, a metal ion solution supply opening, a gas supply opening for supplying a gas for atomizing the metal ion solution in the vicinity thereof, and a protective gas for protecting the metal ion solution supply opening, It may have a protective gas supply opening. These openings may be provided in parallel, may have a multi-layer structure, or may have a part in a multi-layer structure and the other in parallel.

An embodiment of a conventional method for producing metal fine particles by a combustion method will be described. FIG. 6 shows a conventional method for producing fine metal particles by a typical combustion method. The metal ion solution 12 is pumped by compressed air 16 pressurized by a compressor 13. The flow rate of the ionic solution 12 is adjusted by the solution flow rate control valve 18 and sent to the spray pipe 50, where it is combined with the hydrogen supplied from the hydrogen cylinder 5 and jetted from the jet port 51.
The ejected matter is ignited, and the metal ions are reduced in a hydrogen flame to become metal fine particles. The generated metal fine particles are collected by the metal fine particle collection liquid 27. At this time, the metal fine particle recovery liquid 27 is stirred by the electromagnetic stirrer 25.

In this embodiment, the hydrogen flame rises and wraps the spray tube 50 with the flame, so that solid matter adheres to the jet port 51, the spray tube is deformed, the particle diameter of the obtained metal fine particles is not uniform, Problems such as a short continuous operation time, an explosion easily occurring, and a worker being easily burned occur. On the other hand, FIG. 4 shows an embodiment in which the supply of hydrogen and the supply of the metal ion solution are separated. In this embodiment, although some improvements have been made, the phenomenon in which the hydrogen flame rises is the same, solids adhere to the jet port 55, and the supply amount of the metal ion solution fluctuates with time. As a result, it is necessary to replace the closed spray tube 53, and the productivity of the metal fine particles is reduced. Further, the spray tube 53 undergoes deformation due to overheating. FIG. 5 is an enlarged view of the spray tube 53.

[0025]

Next, an embodiment of the present invention will be described. FIG. 7 is a simple example of an embodiment of the present invention. The metal ion solution supplied from the metal ion solution supply opening 71 is atomized by the gas supplied from the gas supply pipe opening 72. The atomization state of the metal ion solution can be controlled by adjusting the pressure of the gas supplied for atomization. The gist of the present invention is to supply the gas for atomization separately from the supply of the metal ion solution, instead of supplying the gas together with the metal ion solution.

FIG. 2 is a sectional view showing an example of the atomizing device of the present invention. The atomizing device includes a metal ion solution supply pipe 2,
It consists of a gas supply pipe 3 and a protective gas supply pipe 4, all of which are housed in a container, i.e. the atomization device 1. A gas supply pipe 3 is provided on the outer periphery of the metal ion solution supply pipe 2, and a protective gas supply pipe 4 is provided on the outer periphery of the gas supply pipe 3. These three are spout 30
At each opening, that is, the metal ion solution supply opening 7
1. Gas supply opening 72 and protective gas supply opening 73
have. In an example of this embodiment, the present invention provides:
It is needless to say that a device without the protective gas supply pipe 4 and the protective gas supply opening 73 can be used, and a device without the gas supply pipe 3 and the gas supply opening 72 can also be used.

In the embodiment shown in FIG. 2, the atomizing device has a multilayer structure, but is not limited to the multilayer structure. FIG. 8 shows the simple embodiment shown in FIG. 7 in which a protective gas supply pipe 4 for supplying a protective gas and a protective gas supply opening 73 are provided. FIG. 9 shows an atomizing apparatus having a multilayer structure, in which a gas supply pipe 3 is provided in the innermost layer. As described above, in the atomizing device having a multilayer structure, the positions where the gas supply pipe 3, the protective gas supply pipe 4, and the metal ion solution supply pipe 2 are provided are not limited. Also in this embodiment, a device without the protective gas supply pipe 4 and the protective gas supply opening 73 for supplying the protective gas can be used, and the gas supply pipe 3 and the gas supply opening 72 are provided. Needless to say, a device that does not exist can be used.

FIG. 3 shows an example of an embodiment using the atomizing device of the present invention. The metal ion solution is supplied from the metal ion solution supply pipe 2 and sent out from the metal ion solution supply opening 71. The supplied metal ion solution is atomized by the gas supplied from the gas supply pipe 3 and sent out from the gas supply opening 72. The atomized metal ion solution is guided into a hydrogen flame generated by the hydrogen burner 8, where the metal ions are reduced and metal fine particles are generated. The generated metal fine particles are collected by a metal fine particle recovery liquid 2 set on a metal fine particle recovery device 10 provided below the atomizing device.
Collected at 7. The metal fine particle recovery liquid 27 is stirred by the electromagnetic stirrer 25 or the like. At this time, it is needless to say that an apparatus without the protective gas supply pipe 4 and the protective gas supply opening 73 or an apparatus without the gas supply pipe 3 and the gas supply opening 72 can also be used in the present invention. Nor.

In order to avoid the problem of causing the rising combustion flame, a protective gas is supplied from the protective gas supply opening 73. The protective gas is blown in the vicinity of the metal ion solution supply opening 71 to protect the metal ion solution supply opening. Further, since the protective gas is supplied downward, there is an effect of suppressing the rise of the combustion flame. Since the protective gas directly cools the metal ion solution opening 71, the amount of solids attached to the opening 71 is significantly reduced, and the deformation of the opening is reduced. Since the amount of deposits is small and the deformation of the opening is small, the metal ion solution can be supplied stably for a long time.

Since the metal ion solution can be supplied stably over a long period of time, the obtained metal fine particles have high uniformity. At the same time, the frequency of replacing the atomizing device is reduced, and metal fine particles can be stably produced, and the productivity is increased. Also, the risk of burns or the like by the operator is reduced. Further, the protective gas supplied from the protective gas supply opening 73 causes the generated metal fine particles to be sprayed on the metal fine particle recovery liquid 27, and the rate of contact with the metal fine particle recovery liquid 27 increases, and The amount of metal fine particles dissipated therein is reduced, and as a result, the recovery rate of metal fine particles is increased.

The gas used for atomizing the metal ion solution is generally air, but is not limited to this. Other gases such as nitrogen, argon, oxygen, carbon dioxide, or a mixed gas thereof can be used as appropriate. In addition, air is generally used as the protective gas, but this is not limited to air. Other similar gases can be used as appropriate.

FIG. 1 shows an example of an embodiment in which metal fine particles are actually produced by using the atomizing apparatus of the present invention. The metal ion solution 12 is pumped by compressed air 16 pressurized by a compressor 13. Alcohols may be added to the metal ion solution in the sense of assisting combustion.
The supply of metal ion solution is not limited to pumping,
It can be supplied by a pump or the like. The flow rate of the metal ion solution 12 is adjusted by the solution flow rate control valve 18 and sent to the metal ion solution supply opening 71. The metal ion solution is atomized by air ejected from the gas supply opening 72. Here, air is used for atomization, but it is not limited to air. Nitrogen, carbon dioxide, oxygen, mixed gas, and other gases may be used. As the air used for atomization, air compressed by the compressor 14 is used. However, a cylinder having compressed air may be used.

On the other hand, the hydrogen used for combustion is used after adjusting the pressure from the hydrogen cylinder 5 with the pressure control valve 6. The hydrogen whose pressure has been adjusted is sent to a hydrogen burner 8 where it is burned. Although only one hydrogen burner 8 is illustrated in FIG. 1, a plurality of hydrogen burners may be used. The metal ion solution supplied from the ejection port 30 of the atomization device 1 is reduced in a hydrogen flame to become metal fine particles. The generated metal fine particles are collected as metal fine particles in a metal fine particle recovery device 10 provided below the atomizing device. The metal particle collection device 10 includes a metal particle collection liquid 2 for collecting metal particles.
7 generally uses water. Generally, hydrogen is used as the combustion flame, but other reducing flames such as methane gas and carbon monoxide can also be used.

The metal fine particle recovery liquid 27 is appropriately replaced depending on the condition of use. Further, since the temperature of the metal fine particle recovery liquid 27 increases, cooling water is passed through the metal fine particle recovery liquid or the metal fine particle recovery liquid is passed through a heat exchanger to be cooled. In order to improve the recovery rate of the metal fine particles, the metal fine particle recovery liquid is stirred by, for example, the electromagnetic stirrer 25 or the like. The stirring means is not limited to the electromagnetic stirrer.

Further, protection of the metal ion solution opening 71,
That is, a protective gas is supplied from the protective gas supply pipe 4 in order to prevent solids from adhering and to reduce deformation of the opening due to overheating of the combustion flame. The protective gas is supplied around the metal ion solution supply opening 71 near the ejection port 30 of the atomization device. In general, since the combustion flame rises to the metal ion solution supply opening 71, solids adhere to the opening 71 due to the high temperature of the combustion flame, and the opening is deformed. The protective gas serves to prevent solid matter from adhering to the metal ion solution supply opening 71 and to prevent the opening from being deformed. Since the protective gas is supplied downward, the rise of the combustion flame is suppressed. Due to both the direct protection by the protective air and the effect of pushing the combustion flame downward, the temperature rise of the metal ion solution supply opening 71 is suppressed, and the adhesion of solid matter at the opening 71 is significantly reduced. Part deformation can also be reduced. In this embodiment, it goes without saying that an apparatus without the gas supply pipe 3 or the protective gas supply pipe 4 can be used.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.
Platinum colloid was produced using the apparatus shown in FIG. The preparation conditions of the used solution and the like, and the manufacturing conditions such as the combustion condition are as follows. Dissolve 10 g of platinum in 50 ml of aqua regia,
To this, 120 ml of 95% ethanol was added, and distilled water was further added to make the whole 300 ml, and the platinum ion solution was adjusted. The metal fine particle recovery liquid was prepared by adding 1% of a surfactant to 5 l of distilled water. On the other hand, hydrogen has a combustion temperature of 6
The hydrogen flow rate was adjusted to be in the range of 20 to 680 ° C.
The manufacturing operation was performed according to the procedure already described. The results obtained are shown in Table 1.

[0037]

[Table 1]

In Comparative Example 1, metal fine particles were produced according to the conventional embodiment shown in FIG.
Is a conventional embodiment in which metal fine particles are manufactured according to FIG. From these results, it can be seen that, when the metal fine particles are manufactured according to the present invention, the recovery rate of the metal fine particles is high, and the metal fine particles can be continuously produced stably.

[0039]

According to the present invention, the metal ion solution is supplied by atomizing the metal ion solution with a gas, reducing the atomized gas in a reducing flame, and supplying protective air to protect the metal ion solution supply opening. The adhesion of solids at the openings is significantly reduced, and the metal ion solution can be supplied stably over a long period of time. Also, the overheating deformation of the metal ion solution supply opening is small. Therefore, the obtained metal fine particles have high uniformity. At the same time, the frequency of replacing the atomizing device is reduced, metal particles can be produced stably, and productivity is increased. Also, the risk of burns or the like by the operator is reduced. Due to the protective gas supplied from the protective gas supply opening, the rate at which the generated metal fine particles come into contact with the metal fine particle collection liquid 27 increases, and the amount of metal fine particles scattered into the air decreases. The recovery rate of fine particles is increased.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an embodiment of the present invention.

FIG. 2 is a diagram showing an example of an atomizing device of the present invention.

FIG. 3 is a diagram showing an example of an embodiment of the atomization device of the present invention.

FIG. 4 is a diagram showing an example of an embodiment in the conventional production of metal fine particles.

FIG. 5 is a diagram showing an example of an embodiment of a conventional atomizing device.

FIG. 6 is a view showing another example of the embodiment in the conventional production of metal fine particles.

FIG. 7 is a view showing another example of the atomizing device of the present invention.

FIG. 8 is a diagram showing another example of the atomizing device of the present invention.

FIG. 9 is a view showing another example of the multilayer structure type atomization apparatus of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 atomization device 2 metal ion solution supply pipe 3 gas supply pipe 4 protective gas supply pipe 5 hydrogen cylinder 6 pressure control valve 7 pressure gauge 8 combustion burner 9 thermometer (thermocouple) 10 metal particle recovery apparatus 11 metal ion solution container 12 Metal ion solution 13, 14, 15 Compressor 16 Compressed air 17 Pressure regulator 18 Solution flow control valve 19, 20, 21 Pressure gauge 22 Thermometer 23 Recovered liquid outlet 24 Recovered liquid inlet 25 Electromagnetic stirrer 26 Stirrer 27 Metal particles Recovered liquid 30, 51, 55 Spout 50, 53 Spray tube 54 Needle valve 71 Metal ion solution supply opening 72 Gas supply opening 73 Protective gas supply opening

Claims (6)

[Claims] In a method for producing metal fine particles, metal ions are supplied from a metal ion solution supply opening, and the supplied metal ions are supplied to a gas supply opening provided near the metal ion solution supply opening. Atomized by the gas supplied from
A method for producing metal fine particles, wherein atomized metal ions are reduced in a reducing flame to generate metal fine particles. 2. In the method for producing metal fine particles, when metal ions are supplied from a metal ion solution supply opening and reduced in a reducing flame to generate metal fine particles, the metal ion solution supply opening is connected to a combustion flame. A method for producing metal fine particles, wherein a gas is blown to protect the fine particles from metal. 3. A method for producing metal fine particles, wherein metal ions are supplied from a metal ion solution supply opening, and the supplied metal ions are supplied to a gas supply opening provided near the metal ion solution supply opening. Atomized by the gas supplied from
A method for producing metal fine particles, comprising blowing gas to protect metal ion solution supply openings from combustion flame when reducing atomized metal ions in a reducing flame to generate metal fine particles. 4. An apparatus for producing metal fine particles, wherein a metal ion solution supply opening for supplying metal ions and a metal ion solution provided in the vicinity of the metal ion solution supply opening are atomized. An atomizing device for producing fine metal particles, comprising a gas supply opening for supplying a gas. 5. An apparatus for producing metal fine particles, comprising: a metal ion solution supply opening for supplying metal ions; and a protective gas supply opening for protecting the metal ion solution supply opening from a combustion flame. An atomizing apparatus for producing metal fine particles, comprising: 6. An apparatus for producing metal fine particles, comprising: a metal ion solution supply opening for supplying metal ions; and a gas for atomizing the metal ion solution provided near the metal ion solution supply opening. An atomizing apparatus for producing fine metal particles, comprising: a gas supply opening for supply; and a protective gas supply opening for protecting the metal ion solution supply opening from a combustion flame.