JPH06136402A - Method and device for producing magnetic metal powder - Google Patents

Abstract

PURPOSE:To highly efficiently mass-produce a magnetic metal powder without the magnetic characteristic being deteriorated and having a uniform oxide film by continuously supplying a granulated magnetic metal powder consisting essentially of iron on a traveling belt, oxidizing and stabilizing the granulated material in the vapor phase. CONSTITUTION:A magnetic metal powder consisting essentially of iron is granulated to about 1-20mm diameter, oxidized and stabilized in the vapor phase. The granular material to be stabilized is continuously supplied on a gas- permeable belt 3 in a gas-circulated reaction furnace 1 from a raw material storage tank 14. The material is substantially let stand on the belt 3, passed through the furnace and heated to about 40-150 deg.C by a heater 4. An oxygen- contg. gas introduced from an inlet 6 is supplied vertically upwardly through a dispersion plate 2. The linear velocity of the gas is controlled to >=5cm/sec, preferably 15-100cm/sec. A stable magnetic metal powder without the magnetic characteristic being deteriorated and having a uniform oxide film is continuously obtained in this way on an industrial scale.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous method and apparatus for producing metallic magnetic powder. More specifically, the present invention relates to a continuous production method and production apparatus for metal magnetic powder useful for magnetic recording.

[0002]

2. Description of the Related Art In recent years,
Although various recording systems have been developed remarkably, the progress in reduction in size and weight of magnetic recording / reproducing devices is remarkable. Along with this, there is an increasing demand for higher performance of magnetic recording media such as magnetic tapes and magnetic disks. In order to satisfy such requirements for magnetic recording, magnetic powder having high coercive force and high saturation magnetization is required. Conventionally, as magnetic powder for magnetic recording, generally needle-shaped magnetite or maghemite or so-called cobalt-containing iron oxide obtained by modifying these magnetic iron oxide powders with cobalt is used, but in order to obtain a medium with higher output. Has started to use ferromagnetic metal powders with higher coercive force and saturation magnetization, so-called metal magnetic powders.

As a method for producing such metal magnetic powder, generally, iron-like iron compound powder mainly containing acicular hydrous iron oxide or iron oxide is heated in a reducing gas atmosphere such as hydrogen to produce metallic iron. The method of reducing to is used.
However, this magnetic metal powder is chemically unstable and is oxidized in the air, and has a drawback that its magnetic properties deteriorate with the passage of time. In order to solve this drawback, attempts have been made to form an oxide film on the surface of the magnetic metal powder to stabilize it, and various methods have been proposed.

As a conventional stabilization treatment method, a method of suspending a magnetic metal powder to be stabilized in a solvent and blowing an oxidizing gas, so-called liquid phase oxidation (see, for example, JP-A-60
-128202 publication) is known, but the oxidation in the solvent causes the solvent to be oxidized, which has a problem in that the coating film is adversely affected and the safety in handling the solvent is ensured. Also known is a method of forming an oxide film using a gas whose oxygen partial pressure is adjusted in the gas phase, so-called gas-phase oxidation (for example, Japanese Patent Publication No. 59-14081), and this gas-phase oxidation is now known. It is commonplace.

As a reactor used for such gas phase oxidation, a fluidized bed in which gas and solid are in good contact is often used (for example, Japanese Patent Publication No. 59-14081).
59-110701, JP-A-2-192103). However, in the gas-phase oxidation method using a fluidized bed, there is a problem that the agglomeration of the powder particles is promoted by the contact or collision of the powder particles and the magnetic properties are deteriorated, or fine powder is generated and the particles fly out of the reactor. is there.

On the other hand, if the metallic magnetic powder to be stabilized can be gas-phase-oxidized in a stationary state, that is, in a fixed bed, the above problem can be solved, but this stabilizing method has the following problems. That is, the saturation magnetization (σs) of the magnetic metal powder is decreased by the gas phase oxidation, and the amount of decrease is uniquely determined by the gas phase oxidation temperature, but when the gas phase oxidation is performed in the fixed bed, it is generated by the oxidation reaction. Reaction heat may partially accumulate, and only that portion may become high in temperature to lower saturation magnetization more than necessary, or conversely, there may occur a portion that is not oxidized due to gas drift. As a result, the obtained magnetic metal powder has very different saturation magnetization. In some cases, when taken out into the atmosphere, a non-oxidized portion may generate heat or ignite due to a rapid oxidation reaction, and the original coercive force and saturation magnetization may be significantly impaired. Further, such partial accumulation of reaction heat and gas drift are likely to occur as the bed height increases in the fixed bed. Therefore, if (fixed bed layer height / tower diameter) is made small, a metal magnetic powder having a uniform oxide film can be obtained, but such a fixed bed batch gas phase oxidation method has a very high production efficiency. Badly not suitable as an industrial production method.

The present invention has been made in order to solve such a problem, and is a uniform oxide film having no deterioration in magnetic characteristics or variations in magnetic characteristics, particularly saturation magnetization, accompanying a stabilization treatment by vapor phase oxidation. An object of the present invention is to provide a manufacturing method and a manufacturing apparatus for continuously mass-producing the metal magnetic powder having the above-mentioned properties with high efficiency on an industrial scale.

[0008]

Means for Solving the Problems As a result of studying the above-mentioned problems, the present inventors have found that the stabilization treatment by gas phase oxidation is carried out by using a gas flow reactor having a belt through which gas can flow. According to the present invention, it was found that a metal magnetic powder having a uniform oxide film and exhibiting excellent magnetic properties can be obtained, and that such a metal magnetic powder can be continuously produced industrially advantageously, and the present invention has been completed. .

That is, the gist of the present invention is (1) a method for producing a metal magnetic powder, which comprises a step of subjecting a metal magnetic powder containing iron as a main component to a gas phase oxidation using an oxygen-containing gas for stabilization treatment. The stabilized material to be granulated is continuously supplied and placed on a gas flowable belt provided in a gas flow type reaction furnace, while the stabilized material is transferred,
(2) A method for producing a magnetic metal powder, characterized in that gas-phase oxidation with an oxygen-containing gas is performed to continuously perform stabilization treatment,
The manufacturing method according to claim 1, wherein the oxygen-containing gas is supplied vertically upward with respect to the belt surface at a gas linear velocity of 5 cm / sec or more, and (3) an oxygen-containing gas inlet and outlet, and a material to be stabilized. A gas flow type reaction furnace main body having a supply port and a discharge port of the stabilized processed product, a belt conveyor for transferring a stabilized processed product having a belt capable of gas flow provided in the reaction furnace main body, and the oxygen-containing material A gas dispersion plate for uniformly dispersing and supplying the oxygen-containing gas introduced from the gas inlet to the belt surface on which the object to be stabilized is placed, and heating means arranged to heat the inside of the reaction furnace body. And a metal magnetic powder manufacturing apparatus.

First, the manufacturing apparatus used in the method for manufacturing the metallic magnetic powder of the present invention will be described with reference to FIG. 4, which is a schematic explanatory view. The reactor body 40 has an oxygen-containing gas inlet 44
And a sealed horizontal container having an outlet port 45 for oxygen-containing gas, a supply port 46 for the material to be stabilized, and an outlet 47 for the stabilized material. A heating means 4 is provided around the reactor body.
3 is provided. The heating means is not particularly limited as long as it can heat the material to be stabilized to the gas phase oxidation temperature. For example, a combustible fuel combustion method, an electric furnace method, a jacket method, or the like can be used. In the present invention, for the purpose of keeping the gas-phase oxidation temperature in the reaction furnace body 40 constant, heat insulation is usually performed by using a heat insulating material.

A belt conveyor 41 is provided in the reactor body for transferring the material to be stabilized. The shape of the belt is a mesh that can hold the granulated material to be stabilized, and has a ventilation ratio that has an opening ratio that reduces the pressure loss when the oxygen-containing gas flows through the pores of the belt surface. There is no particular limitation as long as it is an endless belt or the like. For example, a mesh belt, a perforated plate belt, etc. may be mentioned. In the present invention, the object to be stabilized is held in a belt through which gas can flow, and the object to be stabilized is brought into a fluidized state on the belt due to the gas flow and the objects to be stabilized come into contact with each other. In order to prevent the stabilization target material from scattering and to prevent the stabilization target material from scattering, the stabilization target material, which is a metal magnetic powder to be stabilized, is a granulated material (hereinafter, "granulation stabilization target material").
May be abbreviated). Also,
The driving device for transfer is not particularly limited, and for example, a rotation speed variable motor or the like is suitable.

An oxygen-containing gas inlet 4 is provided in the reactor body.
A gas dispersion plate 42 is provided in order to uniformly disperse and supply the oxygen-containing gas introduced from No. 4 to the belt surface on which the granulated material to be stabilized is placed. Perforated plate as the gas dispersion plate,
Various shapes such as a sintered metal plate, a wire mesh type, and a cap type can be adopted. Further, the gas dispersion plate may be installed on the upper side of the belt on which the material to be stabilized for granulation is placed, or on the lower side of the return surface of the belt. As shown in, it is installed between the surface on which the granulated material to be stabilized is loaded and the return surface. At that time, one dispersion plate may be installed according to the effective gas phase oxidation reaction length of the belt (the length of the belt surface on which the material to be stabilized is placed), or several dispersion plates may be installed. May be continuously installed in the running direction of the belt. The oxygen-containing gas is preferably supplied to the gas dispersion plate 42 by a blower or the like having a discharge pressure equal to or higher than the pressure loss when the gas flows through the gas dispersion plate, the belt, the granulated material layer to be stabilized, and the like. .

The manufacturing apparatus of the present invention is provided with an appropriate gas seal structure so that the oxygen-containing gas ejected from the gas dispersion plate can effectively flow through the belt surface without passing through the side surface (end portion) of the belt. It is preferably provided. Examples of this structure include a structure in which a seal wall is provided on the side surface of the gas dispersion plate and the belt, and a structure in which the side surface of the gas dispersion plate and the belt are in close contact with the side wall of the reactor body.

Next, a method for producing the metallic magnetic powder of the present invention will be described. The production method of the present invention is a method for producing a metal magnetic powder, which comprises a step of subjecting a metal magnetic powder containing iron as a main component to a gas phase oxidation using an oxygen-containing gas to perform a stabilization treatment, in which an object to be stabilized is granulated. Is continuously supplied and placed on a belt in which a gas can flow, which is provided in a gas flow type reaction furnace, and the substance to be stabilized is transferred and stabilized by gas phase oxidation with an oxygen-containing gas. It is characterized in that the processing is continuously performed. The manufacturing method of the present invention can be suitably performed using the manufacturing apparatus described above.

Explaining this with reference to FIG. 4, the oxygen-containing gas is introduced from the oxygen-containing gas inlet 44 and dispersedly supplied from the gas dispersion plate 42 to the surface of the belt conveyor 41 through which the gas can flow, in the holes on the surface of the belt conveyor 41. And is discharged from the discharge port 45. While the oxygen-containing gas is thus circulated through the belt conveyor, the heating means 43 heats the inside of the reaction furnace body 40 at a predetermined vapor phase oxidation temperature. The oxygen-containing gas introduced from the oxygen-containing gas inlet 44 may be heated by an external heat exchanger (not shown) or the like. On the other hand, the granulated object to be stabilized is continuously supplied on the belt conveyor 41 from the supply port 46 of the object to be stabilized and placed, and the object to be stabilized is shown in the figure by the belt conveyor. While transferring in the direction of arrow A, an oxygen-containing gas is circulated in the material layer to be stabilized to continuously perform stabilization treatment by gas phase oxidation. The obtained stabilized product is collected from the discharge port 47 of the stabilized product.

The substance to be stabilized to be used in the present invention is not particularly limited, but it is usually produced by heating and reducing an iron compound powder mainly containing hydrous iron oxide or iron oxide as a starting material. Examples of hydrous iron oxide include α
-FeOOH, β-FeOOH, γ-FeOOH and the like can be mentioned. Examples of iron oxide include α-Fe ₂ O ₃ and γ
_{-Fe 2 O 3, Fe 3 O} 4 and the like. Elements such as cobalt, zinc, copper, chromium, nickel, silicon, aluminum, tin and titanium may be added to these hydrous iron oxides or iron oxides. The shape of the iron compound powder mainly containing iron oxide hydroxide or iron oxide is not particularly limited as long as it is needle-like, and specifically, a strip shape,
It includes a spindle shape, a spindle shape, a rice grain shape and the like. Among these, the effect of the present invention becomes more effective particularly when fine particles of needle crystals having a length of 0.3 μm or less and an axial ratio of 5 or more are used.

In the present invention, the substance to be stabilized (the metal magnetic powder to be stabilized) produced by heating and reducing them is subjected to gas phase oxidation using a gas containing oxygen to obtain the substance to be stabilized. A stabilizing treatment is performed by forming an oxide film made of an oxide on the surface of the particles. The heating reduction method is not particularly limited, and a commonly known method is used.

In the present invention, for the reasons described above, such an object to be stabilized is used in a granulated state, that is, as an object to be granulated and stabilized. At this time, the shape of the granulated material to be stabilized is not particularly limited, but the weight average particle diameter is 1 mm or more 2
It is preferable to use granules having a size of 0 mm or less. 1
For the granulated material to be stabilized having a diameter of less than mm, when the oxygen-containing gas is brought into contact with the granulated material to be stabilized at a preferable gas flow rate, the granulated material to be stabilized tends to be in a fluidized state, Stabilized products jump out from the belt conveyor,
The magnetic properties may deteriorate due to the collision of granules. If it exceeds 20 mm, the diffusion of the oxygen-containing gas in the granulated material to be stabilized becomes poor and the resulting oxide film becomes non-uniform. As a method for granulating the material to be stabilized, a known method is used, and examples thereof include stirring rolling granulation, fluidized granulation, extrusion granulation and crush granulation.

The oxygen-containing gas used in the present invention includes
A mixed gas of oxygen or air and an inert gas can be used. The inert gas is a gas which does not substantially react with the magnetic metal powder under the contact treatment condition, and specific examples thereof include N ₂ , He, Ne, Ar and CO ₂ alone or in a mixture. The oxygen concentration in the mixed gas is preferably 100 ppm or more and 2500 ppm or less, and 150 ppm or more and 2000
ppm or less is more preferable. Oxygen concentration in mixed gas is 10
If it is less than 0 ppm, it takes a long time for the stabilization treatment, which is not industrially preferable. If it exceeds 2500 ppm, the oxidation reaction rapidly occurs, the reaction temperature rises, and it becomes difficult to maintain a constant reaction temperature, which is not preferable.

The preferred gas flow rate varies depending on the particle size of the granulated material to be stabilized, but it is preferably 5 cm / sec or more, and 10 cm / sec in the gas linear velocity vertically upward with respect to the belt surface.
sec or more is more preferable, 15 cm / sec or more 10
0 cm / sec or less is particularly preferable. The gas linear velocity is the velocity at the gas phase oxidation temperature. Gas linear velocity is 5c
If it is less than m / sec, the effect of removing the reaction heat by the gas flow becomes small, so that it becomes difficult to keep the reaction temperature constant, and the reaction heat is partially accumulated, and only that part becomes high temperature, and the saturation magnetization becomes higher than necessary. May decrease. In addition, since a nonuniform flow of gas is likely to occur, a portion that is not oxidized may occur. As a result, a magnetic metal powder with extremely different saturation magnetization is obtained, and in some cases, when taken out into the atmosphere, the unoxidized part generates heat or ignites due to a rapid oxidation reaction, and the coercive force originally possessed. And the saturation magnetization may be significantly impaired, which is not preferable.

The layer thickness of the granulated material to be stabilized on the belt is usually 30 cm or less, preferably 25 cm or less.
When the layer thickness exceeds 30 cm, even if the gas linear velocity of the oxygen-containing gas is 5 cm / sec or more as described above, the formation of an oxide film may be non-uniform due to partial accumulation of reaction heat or gas drift. This is because.

The gas phase oxidation reaction temperature is preferably 40 ° C. or higher and 150 ° C. or lower, more preferably 50 ° C. or higher and 130 ° C. or lower. It is particularly preferably 50 ° C. or higher and 100 ° C. or lower. If the reaction temperature is lower than 40 ° C, surface oxidation is not sufficiently performed,
It ignites when taken out into the atmosphere. If the temperature exceeds 150 ° C., the surface is oxidized more than necessary and high saturation magnetization cannot be obtained, which is not preferable. Further, since the saturation magnetization of the metal magnetic powder after being stabilized by vapor phase oxidation is uniquely determined by the reaction temperature, it is necessary to maintain the reaction temperature at a substantially constant reaction temperature within the above range depending on the desired saturation magnetization. The substantially constant reaction temperature means a predetermined temperature ± 5 ° C. If the reaction temperature fluctuates beyond ± 5 ° C, a metal magnetic powder having a desired saturation magnetization cannot be obtained.

Residence time in the reaction furnace main body, that is, the time from when the granulated material to be stabilized is supplied onto the belt in the reaction furnace body until it exits from the discharge port of the stabilized material (gas phase oxidation reaction The time) is usually 1 to 20 hours, preferably 1.5 to 18 hours, although it depends on the above conditions. If the time is shorter than 1 hour, the stabilization treatment by vapor phase oxidation is insufficient, and if the time is longer than 20 hours, there is no problem in terms of the quality of the metal magnetic powder, but the production efficiency is low, which is not preferable. In the present invention, the gas phase oxidation is carried out by thus providing a certain residence time, and since the gas phase oxidation can be carried out in a substantially stationary state, the particles collide with each other and the generation of fine powder occurs. In addition, it is possible to produce a metallic magnetic powder which has good contact between the substance to be stabilized and the oxygen-containing gas, has a uniform oxide film, and has excellent magnetic properties. Such a residence time can be usually adjusted by changing the traveling speed of the belt by controlling the driving motor or the like.

By the manufacturing method of the present invention as described above, it is possible to continuously mass-produce metal magnetic powder having a uniform oxide film and exhibiting excellent magnetic characteristics on an industrial scale with high efficiency.

[0025]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Embodiment 1 (Example of Manufacturing Apparatus) FIG. 1 is a longitudinal sectional view showing an example of the manufacturing apparatus of the present invention, and FIGS. 2 and 3 are sectional views showing respective parts of the manufacturing apparatus. is there. The size of the reactor body 1 is 390 m wide
m, height 620 mm, length 3900 mm. As a heating means, an electric furnace system using an electric heater 4 for heating and a heat insulating material 5 is adopted.

The belt 3 is a steel endless mesh belt (mesh diameter 0.15 mm) having a width of 300 mm and an effective gas phase oxidation reaction length of 3000 mm. This belt has a sectional shape as shown in FIG. 3 in order to prevent the granulated material to be stabilized from falling off from the end portion of the belt. Then, this belt travels at a constant speed in the direction of arrow A in the figure by the belt drive roller 11 and the drive motor 21 provided outside the reactor main body. The roller drive shaft 12 has a shaft seal 20 for sealing an oxygen-containing gas.
Is provided. The gas dispersion plate 2 is a perforated plate having a cross section of 300 × 300 mm. This gas dispersion plate has eight dispersion plates continuously installed below the surface of the mesh belt on which the material to be granulated and stabilized is placed. Further, as shown in FIG. 2, the gas seal wall 22 is provided so that the oxygen-containing gas ejected from the gas distribution plate does not pass through the side surface of the belt but effectively flows through the belt surface.

A raw material feeder 13 for continuously supplying the granulated material to be stabilized in the raw material storage tank 14 onto the mesh belt is directly connected to the supply port 8 of the material to be stabilized in the reactor body. . A screw feeder was used as the raw material feeder. Further, the thickness adjusting plate 10 is provided in order to make the granulated material to be stabilized supplied on the mesh belt a constant layer thickness on the mesh belt, and has an adjusting mechanism capable of changing the layer thickness. . The layer thickness can be adjusted by controlling the rotation speed of the raw material feeder 13 and changing the set thickness of the thickness adjusting plate 10 as to the supply speed of the granulated material to be stabilized. The granulated substance to be stabilized having a constant layer thickness moves in the direction of arrow A in the figure by the belt, and is introduced into the reactor main body from the oxygen-containing gas inlet 6 and ejected from the gas dispersion plate. And is continuously vapor-phase oxidized. Residence time of the granulated material to be stabilized (time from when the granulated material to be stabilized is supplied onto the belt in the reactor body until it exits from the discharge port 9 of the material to be stabilized),
That is, the gas-phase oxidation time can be adjusted by the traveling speed of the belt, but in order to appropriately control the traveling speed of the belt, the drive motor 21 has a mechanism capable of variably controlling the rotation speed of the motor. A product storage tank 15 is connected to the discharge port 9 of the stabilized material in order to recover the metal magnetic powder obtained after a predetermined vapor phase oxidation time. Further, the raw material storage tank 14 and the product storage tank 15 are purged with nitrogen gas so that the oxygen-containing gas and the stabilized product do not come into direct contact with the atmosphere.

Example 2 (Production Example) The granulated material to be stabilized used in the stabilization treatment was Al
A needle-like crystal α-FeOOH having a major axis length of 0.22 μm and an axial ratio of 10 containing 4% by weight with respect to e is extruded into a granule having a weight average particle diameter of 3 mm, It is then heat-reduced. The magnetic properties of the material to be stabilized before the stabilization treatment were measured by immersing it in toluene and subsequently air-drying it in the air, and then measuring the coercive force (H
c): 1610 [Oe], saturation magnetization (σs): 142
[Emu / g], squareness ratio (σr / σs): 0.52
It was [-]. This was subjected to gas phase oxidation at 70 ° C. using an air / nitrogen mixed gas containing 500 ppm of oxygen by the manufacturing apparatus shown in Example 1. The oxygen-containing gas has a gas linear velocity of 35c vertically upward with respect to the mesh belt surface.
It was distributed so that it would be m / sec.

The above-described granulated material to be stabilized is filled in the raw material storage tank 14 without exposing it to the atmosphere, and then the raw material feeder 13 is used.
Was continuously fed at a rate of 5.5 kg / hr into the reactor body heated to the gas phase oxidation temperature. The layer thickness of the granulated material to be stabilized on the mesh belt was set to 15 cm by the thickness adjusting plate 10. The granulated material to be stabilized was continuously gas-phase oxidized while moving in the direction of arrow A together with the belt and in contact with the oxygen-containing gas flowing through the mesh belt. The residence time in the reaction furnace main body of the granulated material to be stabilized was set to 8 hours by adjusting the traveling speed of the belt by the belt driving motor 21 provided outside the reaction furnace main body.

Under the above set conditions, 6.1 is stored in the product storage tank.
It was possible to obtain a metal magnetic powder of kg / hr. A sample vibrating magnetometer (VS
The magnetic properties were measured by M), and the retention of the saturation magnetization after standing for one week under the oxidation-promoting conditions of 60 ° C. and 90% relative humidity was measured. As a result, coercive force (Hc): 1575
[Oe], saturation magnetization (σs): 129 [emu / g],
The squareness ratio ([sigma] r / [sigma] s) was 0.52 [-] and the saturation magnetization retention rate was 82 [%], indicating excellent magnetic properties.

Example 3 (Production Example) As a granulated material to be stabilized, a needle containing Si in an amount of 3% by weight and having a primary particle size having a major axis length of 0.25 μm and an axial ratio of 10. It was carried out under the same conditions as in Example 2 except that the crystalline α-Fe ₂ O ₃ was extruded to form a granulated product having a weight average particle diameter of 3 mm, and the granulated product was heated and reduced. The magnetic properties of the object to be stabilized before the stabilization treatment were measured in the same manner as in Example 2, and the coercive force (H
c): 1580 [Oe], saturation magnetization (σs): 148
[Emu / g], squareness ratio (σr / σs): 0.51
It was [-]. As a result, it was possible to obtain a metal magnetic powder which was stabilized at 6.0 kg / hr. The magnetic characteristics of this metal magnetic powder are as follows: Coercive force (Hc): 1550 [O
e], saturation magnetization (σs): 133 [emu / g], squareness ratio (σr / σs): 0.51 [−], saturation magnetization retention rate:
It was 82 [%] and had excellent magnetic properties.

[0033]

EFFECT OF THE INVENTION By using the manufacturing method and the manufacturing apparatus of the present invention, the object to be stabilized can be gas-phase oxidized in a substantially stationary state on the belt, so that there is no collision between particles or generation of fine powder. It is possible to produce a metal magnetic powder that has good contact between the material to be stabilized and the oxygen-containing gas, has a uniform oxide film, and has excellent magnetic properties. Further, it becomes possible to continuously produce such a high-quality metal magnetic powder industrially advantageously.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an example of a manufacturing apparatus of the present invention.

FIG. 2 is a sectional view taken along line II-II of the manufacturing apparatus in FIG.

FIG. 3 is a cross-sectional view of the manufacturing apparatus of FIG. 1 taken along the line I-I.

FIG. 4 is a schematic explanatory view of a manufacturing apparatus of the present invention.

[Explanation of symbols] 1 reactor main body 2 gas dispersion plate 3 belt 4 electric heater for heating 5 heat insulating material 6 inlet for oxygen-containing gas 7 outlet for oxygen-containing gas 8 supply port for stabilized material 9 stabilized material Discharge port 10 Thickness adjusting plate 11 Belt drive roller 12 Roller drive shaft 13 Raw material feeder 14 Raw material storage tank 15 Product storage tank 16 Nitrogen purge gas inlet 17 Nitrogen purge gas outlet 18 Nitrogen purge gas inlet 19 Nitrogen purge gas outlet 20 Shaft seal 21 Drive motor 22 Gas seal Wall 40 Reactor body 41 Belt conveyor 42 Gas dispersion plate 43 Heating means 44 Oxygen-containing gas inlet 45 Oxygen-containing gas discharge port 46 Stabilized product supply port 47 Stabilized product discharge port

Claims (3)

[Claims] 1. A method for producing a metal magnetic powder, which comprises a step of subjecting a metal magnetic powder containing iron as a main component to a gas phase oxidation using an oxygen-containing gas to perform a stabilizing treatment, wherein a granulated substance to be stabilized is gasified. It is continuously supplied and placed on a belt in which a gas can flow, which is provided in a flow-type reaction furnace, and the stabilization treatment is carried out by carrying out gas phase oxidation with an oxygen-containing gas while transferring the substance to be stabilized. A method for producing a magnetic metal powder, which is characterized in that it is carried out continuously. 2. The manufacturing method according to claim 1, wherein the oxygen-containing gas is supplied vertically upward with respect to the belt surface at a gas linear velocity of 5 cm / sec or more. 3. A gas flow type reaction furnace main body having an inlet and an outlet for an oxygen-containing gas, and a supply port and a discharge port for the stabilized material, and a gas flow type reaction furnace body provided in the reactor body. A belt conveyer for transporting an object to be stabilized having a belt through which a gas can flow, and an oxygen-containing gas introduced from the inlet of the oxygen-containing gas is uniformly dispersed and supplied to the belt surface on which the object to be stabilized is placed. An apparatus for producing magnetic metal powder, comprising: a gas dispersion plate for heating; and a heating means arranged to heat the inside of the reaction furnace body.