JPH02221105A - Device for producing metal oxide powder - Google Patents

Abstract

PURPOSE:To obtain the classified coarse particle size and fine particle size metal oxide powders by providing a large-diameter reaction chamber communicating with a small-diameter long tubular reaction chamber and collecting the powder formed by the combustion flame in each reaction chamber from the suction port provided in each reaction chamber. CONSTITUTION:The long tubular first reaction chamber 2 and the second reaction chamber 3 communicating with the first reaction chamber 2 and having an inner diameter larger than that of the first reaction chamber are provided. The metal powder 5 (e.g. Al powder is transported by a carrier gas 6 and supplied into the first reaction chamber 2 via a powder supply passage 10. Gaseous oxygen 7 and an ignition gas 8 (e.g. gaseous propane) are simultaneously supplied into the first reaction chamber 2, and a combustion flame 16 is produced to oxidize the metal powder 5. The coarse particle size metal oxide powder formed in the first reaction chamber 2 is sucked from a first suction port 18 and collected, and the fine particle size metal oxide powder formed in the second reaction chamber 3 is sucked from a second suction port 19 and collected.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an apparatus for producing metal oxide powder, which is a raw material for high-purity ceramic powder, by burning metal powder, and in particular, relates to an apparatus for producing metal oxide powder, which is a raw material for high-purity ceramic powder, by burning metal powder. This relates to a manufacturing device that is capable of classifying and collecting powder according to its particle size.

[Prior Art] Conventionally, in order to produce metal oxide powder by combustion of metal powder, a combustion flame is formed with oxidizing gas and metal powder, and the metal powder is evaporated and burned to extract metal oxide powder from the combustion exhaust gas. was being collected. The particle size of the metal oxide powder obtained by this method tends to have a wide distribution unless it is particularly controlled because the degree of aggregation of the produced powder during production varies depending on the reaction area of the combustion flame.

Therefore, in order to obtain metal oxide powder with a specific particle size range, J3 controls such as adjusting the amount of metal powder supplied during manufacturing and the temperature of the combustion flame are carried out.

For example, Japanese Patent Application Laid-Open No. 60-25602 discloses that metal powder of the highest quality to form a dust cloud is supplied and oxidized in a combustion flame to obtain metal oxide powder with a particle size of 5 to 10 nm. There is. However, this method can only yield particles with a particle size within the above-mentioned specific range.

Therefore, in order to obtain metal oxide powders with different particle sizes at the same time,
It is necessary to classify the product using a sieve or the like without any particular control. However, there are problems in that classifying the produced fine powder into a predetermined particle size requires complicated operations, is inefficient, and is expensive.

[Problems to be Solved by the Invention] An object of the present invention is to provide a manufacturing apparatus that can generate metal oxide powder and at the same time efficiently classify it based on its particle size.

[Means for Solving the Problems] The metal oxide powder manufacturing apparatus of the present invention includes a first reaction chamber having an elongated cylindrical shape, and a second reaction chamber that is connected to the first reaction chamber and has an inner diameter larger than that of the first reaction chamber. a reaction chamber configured with a reaction chamber; and a powder supply opening opened at an end of the first reaction chamber opposite to the second reaction chamber, and a metal powder is transported and supplied into the reaction chamber by a carrier gas. a powder supply passage provided coaxially with the powder supply passage and opened laterally to the powder supply opening to supply oxygen gas into the reaction chamber; a gas supply passage provided on the side wall of the first reaction chamber; , a first suction port that collects by suction large-sized metal oxide powder generated in the combustion flame portion of the first reaction chamber; and a second suction port that suctions and collects the metal oxide powder formed by the metal oxide powder.

The first reaction chamber has a powder supply opening at one end thereof, an opening of a gas supply path for supplying oxygen gas that opens laterally to the powder supply opening, and a side surface facing the powder supply opening for sucking the product. A first suction port is provided, the end opposite the powder supply opening communicating with a second reaction chamber. The first reaction chamber has an elongated cylindrical shape with an inner diameter smaller than that of the second reaction chamber.

This difference in the inner diameter of the first reaction chamber and the second reaction chamber is necessary to classify metal oxides generated in the combustion flame based on particle size, and the inner diameter of the second reaction chamber is the same as that of the first reaction chamber. It is preferable that the amount is at least twice as large.

The powder supply path is a path for supplying metal powder into the reaction chamber using a carrier gas, and the metal powder is transported from a supply source such as a hopper into the reaction chamber through this powder supply path. As the carrier gas, an inert gas such as nitrogen gas or argon gas is mainly used.

As the metal powder, metals active in oxidation reactions such as aluminum, titanium, and zirconium are preferable.

It goes without saying that the smaller the particle size of the metal powder, the better the reactivity. Therefore, any metal powder other than those mentioned above can be used as long as it has a fine particle size and is active.

The gas supply path supplies oxygen gas to burn and oxidize the metal powder. This gas supply path is coaxially connected to the powder supply path, and each opening is concentric.The opening of this gas supply path flows out toward the wall of the first reaction chamber while rotating. It is preferable to form a swirl.This is because the combustion flame forms a swirl in the first reaction chamber, and the generated metal oxide is pushed out to the outer part by the swirl of the combustion flame, separated, and collected. This is for ease of use.

The first suction port is opened in the tangential direction of the combustion flame.

Providing the first suction port at this position makes it easier to collect only the metal oxides generated from the combustion flame in the first reaction chamber.

Since the first reaction chamber has an elongated cylindrical shape with an inner diameter smaller than that of the second reaction chamber, the combustion flame formed has a cylindrical shape. The oxidation reaction mainly occurs at the interface of this combustion flame. Here, the temperature is high and the concentration of the metal oxides produced is also high, so the produced metal oxides aggregate to become coarse particles and are easily pushed out to the outside of the combustion flame.

The first suction port collects metal oxides generated by the combustion flame in the first reaction chamber. The powder collected at this first suction port is
For example, in the case of aluminum oxidation, the grain size is about 10 μm. Therefore, if collected in this part, metal oxides with coarse particles can be obtained.

An ignition gas supply path for supplying ignition gas into the reaction chamber can also be added to the gas supply path.

This ignition gas is ignited in the reaction chamber to form a flame,
An oxidation reaction is caused in the metal powder supplied from the powder supply path. Note that hydrocarbon gas such as methane gas, propane gas, butane gas, and LNG (liquefied natural gas) is used as the ignition gas.

In addition, the first reaction chamber has a small inner diameter and an elongated shape, so the combustion flame and the side wall are close to each other, so it is preferable to flow cooling gas down along the wall surface in order to improve the heat resistance of the side wall. Therefore, a cooling gas outlet that flows down along the side wall can be provided at the powder supply opening of the first reaction chamber. The gas outlet is provided on the side wall of the first reaction chamber on the side of the powder supply opening or on the side of the powder supply opening,
The opening may be such that the ejected gas stream flows down along the side wall and does not participate in the combustion flame. For example, a slot-shaped opening parallel to the side wall around the entire circumference can be formed in the top of the reaction chamber or in the first reaction part of the side wall.

The cooling gas blown out from the gas outlet forms a gas flow layer downward along the side wall. The metal oxide generated by this gas flow layer is discharged from the first suction port and can be easily collected without adhering to the side wall. This cooling gas flow layer, for example, moves air continuously at a constant velocity along the side walls to protect the side walls of the reaction chamber and to prevent products from adhering to the side walls and constricting the reaction chamber space. It is preferable to let it flow down.

The second reaction chamber has one end communicating with the first reaction chamber, has an inner diameter wider than that of the first reaction chamber, and has a second suction chamber for suctioning and collecting metal oxides generated by the combustion flame in the second reaction chamber. have a mouth

In the second reaction chamber, the combustion flame formed in the first reaction chamber is guided to the second reaction chamber, which has an inner diameter larger than that of the communication portion, so that the flow is disturbed and the combustion flame spreads, causing an oxidation reaction. Therefore, unlike in the case of the first reaction chamber, the product is diffused over a wide space and its concentration is reduced, making it difficult for aggregation to occur. Furthermore, the temperature of the combustion flame is lower than that in the first reaction chamber, and the grain growth of the generated powder is inhibited and the grain size becomes smaller.

Further, it is preferable that the continuous portion between the first reaction chamber and the second reaction chamber spread out in a tipper shape, since this can prevent the combustion flame from spreading rapidly and preventing the oxidation reaction from being carried out sufficiently.

The metal oxide produced in this second reaction chamber is collected through the second suction port. The metal oxide powder collected here has a small particle size.

Therefore, the production apparatus can easily classify and collect particles into coarse particles and fine particles through the two suction ports provided in the first reaction chamber and the second reaction chamber, respectively.

[Function] According to the metal oxide powder production apparatus of the present invention, the reaction chamber is divided into a first reaction chamber and a second reaction chamber, which are communicated with each other, and the inner diameter of the first reaction chamber is made smaller than that of the second reaction chamber. It has a small, elongated cylindrical shape, and a suction port is provided in each of the first reaction chamber and the second reaction chamber.

In the first reaction chamber, a small-diameter, elongated cylindrical combustion flame is formed, and the oxidation reaction occurs at the interface.

There, the temperature is high and the concentration of metal oxides produced is also high.

Therefore, the generated metal oxide tends to aggregate and grow into coarse particles, and is easily pushed out to the outside of the combustion flame. If this product is collected through the first suction port, 1q of coarse and large-particle metal oxides will be obtained. On the other hand, since the second reaction chamber has a wider inner diameter than the first reaction chamber, the oxidation reaction in the combustion flame has a lower temperature and a lower concentration of products than in the first reaction chamber. Therefore, the particle size of the product produced is reduced.

As mentioned above, the metal oxides generated in each reaction chamber are collected by suction separately from the suction port provided in each reaction chamber, and the metal oxides are separated into coarse particle size and fine particle size. can be classified. Therefore, metal oxide powders with two different particle sizes can be obtained at the same time.

[Example code] This will be explained in detail below using examples.

FIG. 1 shows a schematic structural explanatory diagram of a metal oxide powder manufacturing apparatus according to an embodiment of the present invention.

This manufacturing apparatus consists of a first reaction chamber 2 having an elongated cylindrical shape whose inner diameter is smaller than the inner diameter of the second reaction chamber 3, and a second reaction chamber 3 having a tipper-shaped opening communicating with the first reaction chamber 2. 1, and a powder supply path 10 having a powder opening opened in the clay wall of the first reaction chamber 2 and supplying aluminum powder 5 into the reaction chamber 1.
a gas supply path 12 that is provided coaxially with the powder supply path 10 and supplies oxygen gas 7 into the reaction chamber 1; and a gas supply path 12 that is provided coaxially with the gas supply path 12 that supplies oxygen gas 7 into the reaction chamber 1. a gas supply path 11 that supplies propane gas 8; a first suction port 14 that collects products in the first reaction chamber 2; and a second suction port 15 that collects products in the second reaction chamber 3; First reaction chamber 2
and a gas outlet 13 that blows out cooling air 17 downward along the side wall.

The inner peripheral surface of the reaction chamber 1 is formed of a heat insulating material.

The inner diameter of this reaction chamber 1 is such that the inner diameter of the first reaction chamber 2 is approximately half the inner diameter of the second reaction chamber 3, and the continuous portion thereof is in a tipper shape and communicates with the second reaction chamber 3.

The powder supply path 10 is provided with a hopper 4 into which aluminum powder 5 is charged, and is supplied to the reaction chamber 1 by nitrogen gas as a carrier gas 6.

Oxygen gas 7 is supplied from the gas supply path 12 to the reaction chamber 1 by opening the valve. The opening of the oxygen gas supply path 12 supplies the oxygen gas while swirling it and causes it to flow out toward the wall of the reaction chamber 1. For example, a swirler is provided to allow the oxygen gas to flow out. As a result, the combustion flame 16 forms a vortex and performs an oxidation reaction.

From the gas supply path 11, propane gas as the ignition gas 8 is supplied to the reaction chamber 1 by opening the valve.

The gas outlet 13 is provided around the side wall of the first reaction chamber 2, and has a narrow groove-like opening such that the discharged air 17 flows downward along the side wall. An enlarged schematic diagram of an example of the gas outlet 13 is shown in FIGS. 2 and 3.

This gas outlet 13 is opened all around the side wall in order to form a gas flow over the entire surface of the side wall. FIG. 2 shows an example in which the gas outlet 13 is provided in a side wall, and FIG. 3 shows an example in which the gas outlet 13 is provided in an earthen wall.

A first suction port 14 that opens tangentially to the circumference of the combustion flame 16- is provided on the side wall at the end of the first reaction chamber 2, and sucks the metal oxide powder generated in the first reaction chamber 2. 18 Collection unit (not shown) that collects and separates combustion exhaust gas and products
It is connected to the.

The combustion flame 16 extending from the first reaction chamber 2 spreads in the second reaction chamber 3, where unreacted metal powder in the combustion flame 16 is oxidized. The oxidized powder is collected by suction 19 from a second suction port 15 provided at the bottom of the second reaction chamber 3, and is connected to a collection unit (not shown) that separates combustion exhaust gas and products. .

A method for producing aluminum oxide powder using the apparatus of this embodiment configured as described above will be explained.

First, 350 meshes of aluminum powder 5 is charged into the hopper 4. Next, listen to the valve and gas supply line 12
At the same time, oxygen gas 7 is supplied to the reaction chamber 1 at a flow rate of 10 to 15 rl/)-1r, and the gas supply path 1 is
Add propane gas 8 for ignition to 1 at 0.7m'/1-1r.
A pilot flame is formed by an ignition means (not shown).

And aluminum powder 5 from hopper 4 to 6 3/[''
An amount of r was supplied to the reaction chamber 1 using the nitrogen gas of the carrier gas 6 at a flow rate of 6 m]/Hr.

The aluminum powder 5 supplied into the reaction chamber 1 is combusted by contacting the pilot flame, and a combustion flame 16 is formed to spread throughout the reaction chamber 1 . The oxygen gas 7 flows out into the reaction chamber 1 by rotating the opening in the tangential direction with respect to the center line of the reaction chamber 1, thereby forming a vortex in the combustion flame 16-.

At this time, in order to prevent the combustion flame 16' from spreading laterally, the diameter of the reaction chamber 1 is set to be half that of the second reaction chamber 3. As a result, the distance between the side wall and the combustion flame 16- becomes short, so in order to increase the heat resistance of the side wall, air 1 is directed downward from the gas outlet.
7 was allowed to flow out at 10-15 m1/Hr over the entire circumference of the side wall.

The metal oxide formed in the first reaction chamber 2 is transferred to the first suction port 1
4 and separated from the combustion exhaust gas by a bag filter. The average particle size of the obtained aluminum oxide powder was 5 to 40 μm.

- The oxides generated in the reaction chamber 3 of the power cylinder 2 were sucked together with the combustion exhaust gas from the second suction port 15 provided directly below the center of the combustion flame 16 and collected by a bag filter 19. The average particle size of the aluminum powder was 0.1-3 μm, thus effectively separating the products based on particle size.

[Effects] The metal oxide powder production apparatus of the present invention is composed of a reaction chamber consisting of two parts: a first reaction chamber that is elongated and cylindrical and has a small inner diameter, and a second reaction chamber that communicates with the first reaction chamber and has a large inner diameter. has been done. Each reaction chamber is provided with a suction port for collecting the product.

Then, the oxides produced by the combustion flame in each reaction chamber are
By collecting with each suction port, it is possible to classify and collect powder into coarse particle size powder and fine particle size powder.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration explanatory diagram of a manufacturing apparatus according to an embodiment, FIGS. 2 and 3 are enlarged schematic diagrams of an example of a gas outlet opening, and FIG. 2 is an example in which a gas outlet is provided on a side wall. FIG. 3 shows an example in which a gas outlet is provided on the upper wall. 1... Reaction chamber 2... First reaction chamber 3...
Second reaction chamber 13... Gas outlet 14... First suction port 15... Second suction port 16.16'...
Combustion flame patent applicant Toyota Motor Corporation representative Patent attorney Hiroshi Okawa

Claims (1)

[Claims] (1) A reaction chamber composed of an elongated cylindrical first reaction chamber and a second reaction chamber communicating with the first reaction chamber and having an inner diameter larger than that of the first reaction chamber; a powder supply passage having a powder supply opening opening at an end opposite to the second reaction chamber and transporting metal powder into the reaction chamber by a carrier gas; and a powder supply passage provided coaxially with the powder supply passage and supplying the powder. a gas supply path that opens concentrically with the supply opening and supplies oxygen gas into the reaction chamber; and a large particle size metal that is provided on the side wall of the first reaction chamber and that is generated in the combustion flame portion of the first reaction chamber. a first suction port that collects the oxide powder by suction; a second suction port that is provided in the second reaction chamber and that collects the metal oxide powder formed in the combustion flame portion of the second reaction chamber by suction; An apparatus for producing metal oxide powder, comprising: