WO1998045073A1

WO1998045073A1 - Method of producing magnetic metal powder

Info

Publication number: WO1998045073A1
Application number: PCT/JP1998/001586
Authority: WO
Inventors: Yoshinori Hama; Shunji Arita; Shuhei Arikita
Original assignee: Kao Corporation
Priority date: 1997-04-10
Filing date: 1998-04-06
Publication date: 1998-10-15
Also published as: JPH10280013A

Abstract

A method of efficiently producing, on an industrial scale, a magnetic metal powder exhibiting excellent magnetic characteristics while preventing the shape change of skeletal particles in the production stage and mutual sintering of the skeletal particles and while keeping the form of granules. Specifically, a method of producing a magnetic metal powder by thermally reducing granules of an iron compound powder in the presence of a reducing gas, comprising putting the granules on a transfer container having a construction capable of allowing the passage of the gas, conveying the container into a thermal reduction furnace, and thermally reducing the granules in the presence of the reducing gas.

Description

Description Manufacturing method of magnetic metal powder Technical field

The present invention relates to a method for producing a magnetic metal powder. More particularly, the present invention relates to a method for producing a metal magnetic powder useful for magnetic recording. Background art

In recent years, there have been remarkable developments in various recording methods, and in particular, there has been a remarkable progress in reducing the size and weight of magnetic recording / reproducing devices. Accordingly, 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, a metal magnetic powder having a high coercive force and a high saturation magnetization is required.

As a method of producing such a metal magnetic powder, generally, a needle-shaped iron compound powder mainly containing hydrated iron oxide or iron oxide is heated in a reducing gas atmosphere such as hydrogen to reduce it to metallic iron. Is used. In this method, as the reduction is performed at a higher temperature, the growth of the crystallites of metallic iron constituting the acicular shaped particles, which are primary particles, is promoted, and the coercive force and saturation magnetization of the metallic magnetic powder can be increased. it can. However, conversely, if the reduction is performed at a high temperature, the needle-like shape of the skeleton particles collapses and sintering of the skeleton particles occurs, and as a result, the coercive force, the squareness ratio, etc. of the metal magnetic powder are reduced. Deterioration of characteristics causes problems. Therefore, in order to obtain a metal magnetic powder having satisfactory performance, it is an issue to be solved how to obtain a metal magnetic powder having good crystallinity while maintaining the acicularity of the raw material particles.

In order to solve this problem, for example, a method using a gas flow type belt-type reactor

(Japanese Unexamined Patent Publication No. Hei 6-933212, Japanese Unexamined Patent Publication No. Hei 6-187281, USP 547) 0 3 7 4).

The method using a gas flow belt furnace is a technology that enables mass production of metal magnetic powder with uniform and excellent magnetic properties, since it is reduced in a substantially stationary state at a low bed height, but the raw material particles are granulated. Therefore, there are the following problems.

Granules having a high porosity are used so that the water vapor generated by the following equations (1) and (2) is easily diffused and removed in the particles, but after the reduction reaction, the granules are used. Since the volume of the formed skeleton particles shrinks, the strength of the granulated material is significantly reduced. Such granules are brittle and easily broken when removed from the reduction reactor, transported to the gas-phase stabilization reactor, and fed to the gas-phase stabilization reactor. If the granulated material is broken, the number of paddy particles increases, so that when placed in a gas-phase stabilization reactor, the powder layer is compacted, the gas flow becomes poor, and the reaction becomes uneven. In addition, fine granules are likely to be in a fluidized state, and the magnetic properties may be degraded due to collision between the granules. In addition, the fine powder scatters outside the reactor or falls off the belt, which lowers the yield.

3 Fe ₂ 0 ₃ + H ₂ → 2 Fe ₃ 0 ₄ + H ₂ 〇 (1)

_{_{F e 3 0 4 + 4 H}} 2 → 3 F e + 4 H 2 〇 (2)

The above problem can be solved by reducing the porosity when forming the granulated material, or by adding a binder to increase the strength of the granulated material so that it does not break easily. When the ratio is small, the water vapor generated in the granulated particles is difficult to be diffused and removed, so that the shape change of the shaped particles and sintering of the shaped particles are likely to occur. In addition, when a binder is added, it is necessary for the binder to remain in the particles even after a high-temperature reduction reaction, but such a binder may reduce the magnetic properties of the reduced product. It is an object of the present invention to provide a method for manufacturing a magnetic metal powder of such fine particles, which prevents the shape change of the shaped particles and the sintering of the shaped particles while maintaining the shape of the granulated material. An object of the present invention is to provide a production method for mass-producing metal magnetic powder exhibiting magnetic properties on an industrial scale with high efficiency.

These and other objects of the present invention will become apparent from the following description. Disclosure of the invention

That is, the gist of the present invention is:

[1] In a method for producing a metal magnetic powder in which an iron compound powder containing hydrous iron oxide and Z or iron oxide as a main component is heated and reduced in the presence of a reducing gas, a granulated product of the iron compound powder can be gas-flowed. A metallic magnetic powder characterized in that it is placed in a transport container having a simple structure, and the transport container is carried into a heat reduction reactor, and the granulated iron compound powder is heated and reduced in the presence of a reducing gas. Method,

[2] A metal that is heated and reduced in the presence of reducing gas in the presence of reducing iron and powdered iron oxides containing iron oxide hydroxide and Z or iron oxide, and the resulting reduced product is subjected to gas phase oxidation in the presence of oxygen-containing gas. In a method for producing a magnetic powder,

(A) The granules of the iron compound powder are placed on a transfer container having a structure capable of flowing gas, and the transfer container is carried into a heating and reduction reaction furnace, and the granules of the iron compound powder are transferred in the presence of a reducing gas. A step of reducing by heating to obtain a reduced product, and

(B) carrying the transport vessel on which the reduced product obtained in the step (A) is placed into a heated gas-phase oxidation reactor, and subjecting the reduced product to gas-phase oxidation in the presence of an oxygen-containing gas;

A method for producing a metal magnetic powder, characterized by providing

C 3] An iron compound powder containing hydrous iron oxide as a main component is thermally dehydrated in the presence of a non-reducing gas, and the obtained thermally dehydrated product is thermally reduced in the presence of a reducing gas to obtain a reduced product. In a method for producing a metal magnetic powder that is subjected to gas phase oxidation in the presence of an oxygen-containing gas,

(C) The granules of the iron compound powder are placed in a transfer container having a structure capable of gas flow, and the transfer container is carried into a heating / dehydration reactor, and the granules of the iron compound powder are subjected to the presence of a non-reducing gas. A step of heating and dehydrating to obtain a dehydrated substance under heating,

(D) The transfer vessel on which the heated dehydrated product obtained in the step (C) is placed, is carried into a thermal reduction reaction furnace, and the heated dehydrated product is reduced by heating in the presence of a reducing gas to obtain a reduced product. Process , as well as

(E) carrying the transport vessel on which the reduced product obtained in the step (D) is placed into a heated gas-phase oxidation reactor, and subjecting the reduced product to gas-phase oxidation in the presence of an oxygen-containing gas;

And a method for producing a metal magnetic powder. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic explanatory view of a gas flow type reactor constituting a production apparatus used in the present invention.

FIG. 2 is a schematic explanatory view of an example of a transport container constituting the manufacturing apparatus used in the present invention.

FIG. 3 is a schematic explanatory view of an example of a transport container constituting the manufacturing apparatus used in the present invention.

FIG. 4 is a schematic explanatory view of an example of a manufacturing apparatus used in the present invention.

FIG. 5 is a schematic explanatory view of an example of a manufacturing apparatus used in the present invention.

FIG. 6 is a schematic explanatory view of an example of a manufacturing apparatus used in the present invention.

FIG. 7 is a longitudinal sectional view showing an example of a heating-reduction reactor, which is a gas-flow reactor, constituting a production apparatus used in the present invention.

FIG. 8 is a cross-sectional view of the manufacturing apparatus of FIG.

The meanings of the symbols in the figure are as follows.

1: reactor body, 2: gas dispersion plate, 3: heating means, 4: gas inlet, 5: gas outlet, 6: transport container, 7: transfer means, 8: carry-in, 9: carry-out, 1 1: Feeder 1, 1 2 ··· Carrier vessel, 1 3: Heated dehydration reactor, 1 4 · · Heat reduction reactor, 15: Heated gas phase oxidation reactor, 16: Transfer means, 1 7: Transfer means, 21: Reinforcing member, 31: Reactor body, 32: Gas dispersion plate, 33: Conveyor vessel, 34: Electric heater for heating overnight, 35: Heat insulator, 36: Drive Mouth roller, 37: supply hopper, 38: inlet, 39: outlet, 40: gas inlet, 41: gas outlet, 50: shaft seal, 51: Drive motor, 52: Roller-one drive shaft, 53: Gas seal wall, 61: Heat reduction reactor, 62: Heated gas phase oxidation reactor, 63: Transfer means. BEST MODE FOR CARRYING OUT THE INVENTION

The production method of the present invention includes, for example, 1) an embodiment in which an iron compound powder containing iron oxide hydroxide and / or iron oxide as a main component is heated and reduced in the presence of a reducing gas (aspect 1), 2) an iron oxide hydroxide And iron compound powder containing iron oxide or iron oxide as the main component is heated and reduced in the presence of reducing gas, and the resulting reduced product is oxidized in the gas phase in the presence of oxygen-containing gas to stabilize the metal magnetic powder. (Embodiment 2), and 3) The iron compound powder containing hydrous iron oxide as a main component is heated and dehydrated in the presence of a non-reducing gas, and the obtained heated dehydrate is reduced by heating in the presence of a reducing gas. An embodiment (Embodiment 3) in which the obtained reduced product is oxidized in the gas phase in the presence of an oxygen-containing gas to stabilize the metal magnetic powder.

First, a gas flow type reaction furnace constituting a production apparatus used in the method for producing a metal magnetic powder of the present invention will be described with reference to FIG. 1 which is a schematic explanatory diagram. Such a reactor can be applied to any of a thermal dehydration reactor, a thermal reduction reactor, and a thermal gas phase oxidation reactor.

The reactor body 1 has a gas inlet 4 and a gas outlet 5, and a carry-in port 8 and a carry-out port 9 of a transfer container 6. It is desirable that the entrance 8 and the exit 9 are provided with gas shut-off means by a conventional method. A heating means 3 is provided around the reactor main body.

The method of the heating means is not particularly limited as long as it can heat an object to be treated such as a granulated iron compound powder, a reduced product, and a heated dehydrated product to a processing 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 processing temperature in the reactor main body constant, it is preferable to perform heat insulation using a commonly used heat insulating material or the like. The transfer means 7 is a means for carrying the transport container 6 into the flow-type reactor and carrying out the transport container 6 after predetermined processing. The transfer device is not particularly limited. For example, the transfer container may be transferred by driving a transfer member using a variable-speed motor, or a transfer port. It is also possible to adopt a configuration in which the transfer containers are sequentially pushed in from 8 and the transfer containers are sequentially unloaded from the discharge port 9.

The transport container 6 is not particularly limited as long as it has a structure through which gas can flow. For example, as shown in FIGS. 2 and 3, the transport container has a ventilated structure with an opening on the bottom and a box-type with an open top. The size of the pores of the opening structure on the bottom surface may be any size that can hold the object to be processed, and is, for example, preferably 0.3 to 20 mm, and more preferably 0.5 to 10 mm. Further, the opening ratio of the bottom surface is not particularly limited, but it is preferable that the pressure loss when gas flows through the bottom surface is smaller, for example, 20 to 90% of the area of the entire bottom surface is preferable, and 30 to 7%. 0% is more preferred.

In such a transport container, the bottom surface serves as a gas flow surface, and the structure of the bottom surface is, for example, a mesh, a perforated plate, or the like. In order to increase the strength of the transport container, it is preferable that the transport container has a structure having a reinforcing member 21 or the like as shown in FIGS. The reinforcing member is desirably disposed so as not to prevent the gas placed in the transfer container from suitably contacting the gas to be processed.

The gas supply means is a means for supplying a predetermined gas into the reactor, and includes at least a gas inlet 4 and a gas outlet 5.

It is preferable to provide a gas dispersing means for uniformly dispersing and supplying the gas introduced from the gas inlet 4 to the transfer container 6 on which the object to be processed is loaded, in the reactor main body. In FIG. 1, a gas dispersion plate 2 is provided as a means for that purpose.

As the gas dispersion plate, various shapes such as a perforated plate, a sintered metal plate, a wire mesh type, a cap type, and a slit type can be adopted. The position of the gas dispersion plate 2 is not particularly limited as long as the gas can be uniformly distributed and supplied to the transport container 6 on which the object to be processed is loaded. . At this time, one dispersion plate may be installed according to the effective treatment length in the reactor main body, or may be divided into several dispersion plates and installed. Further, the gas dispersion plate 2 is preferably installed at a position where the gas can be supplied perpendicularly to the gas flow surface of the transfer container 6. The gas dispersion plate 2 may be installed on the upper part of the transport container 6 as shown in FIG. In this case, gas can be supplied vertically downward with respect to the gas flow surface of the transfer container 6. Alternatively, the gas dispersion plate 2 may be installed at the lower part of the transfer container 6 and gas may be supplied vertically upward with respect to the gas flow surface of the transfer container 6. The supply of the gas to the gas dispersion plate 2 is suitably performed by a blower having a discharge pressure equal to or higher than the pressure loss when the gas flows through the gas dispersion plate 2, the transfer container 6, the object layer, and the like.

The reaction furnace used in the present invention is preferably provided with an appropriate gas sealing structure so that the gas ejected from the gas dispersion plate effectively flows through the inside of the object to be processed mounted on the transfer container. This structure has a seal wall on the side of the gas dispersion plate and the transfer container, a structure in which the gas dispersion plate and the side of the transfer container are in close contact with the side wall of the reactor body, and a close contact between the transfer containers in the unloading direction of the transfer container. And the like. Next, the manufacturing method of the present invention will be described.

1) Aspect 1

Suitable manufacturing apparatuses used in the present embodiment include, for example, a heating reduction reactor having a reducing gas supply means, a transport container having a gas permeable structure, and loading the transport container into the thermal reduction reactor. A transfer means for carrying out after the heat-reduction treatment, wherein the granules of the iron compound powder containing iron oxide hydroxide and / or iron oxide as a main component placed in the transfer container are provided in the presence of a reducing gas. There is a manufacturing apparatus characterized by having a structure capable of being reduced by heating.

FIG. 4 is a schematic explanatory view of an example of a production apparatus suitable for the method for producing a metal magnetic powder of the present embodiment.

The transfer container 6 on which the granulated iron compound powder is placed is carried into the reactor body 1 heated at a predetermined reduction temperature by the heating means 3 from the carry-in port 8, and the granulated iron compound powder is transferred. Heat reduction treatment is performed by flowing a reducing gas through the bed, and the resulting reduced product is carried out from the outlet 9. The reducing gas is supplied into the reactor by the following reducing gas supply means. That is, the gas is introduced from the gas inlet 4, then dispersed and supplied to the transport container 6 by the gas dispersion plate 2, and is discharged from the gas outlet 5 through the holes in the gas flow surface of the transport container. Further, the reducing gas introduced from the gas inlet 4 may be heated by an external heat exchanger (not shown) or the like. The transfer container may be unloaded after the heating and reduction process is completed by stopping in the reactor, or the transfer container may be reduced while being transferred in the direction of arrow A in FIG. The transfer may be a continuous transfer or an intermittent transfer. In consideration of production efficiency, it is preferable to heat and reduce the granulated iron compound powder while transferring the transfer container in the heating and reducing reaction furnace. With such a structure, the granulated iron compound powder placed in the transport container is reduced by heating in the presence of the reducing gas.

The raw material used in this embodiment is an iron compound powder containing iron oxide hydroxide and Z or iron oxide as a main component. Examples of hydrous iron oxide include Hi-FeOOH, S-Fe0OH, and 7-Fe〇OH. The iron oxide, for example, shed one F e ₂ 〇 _{_{_{3, 7- F e 2 0 3}}} , F e 3 0 4 and the like. Elements such as cobalt, zinc, copper, chromium, nickel, silicon, aluminum, tin, and silicon may be added to these hydrous iron oxide and iron oxide. The particle shape of the iron compound powder is not particularly limited as long as it is acicular, and specific examples include a strip shape, a spindle shape, a spindle shape, and a rice grain shape. Among these, the effect of the present invention is more effective when needle-shaped fine particles having a length of 0.3 m or less and an axial ratio of 5 or more are used.

In this embodiment, the iron compound powder is further held in such a manner that the iron compound powder is held in a transfer container having a structure capable of gas flow, and in order to prevent the iron compound powder from being brought into a fluidized state by gas flow and contacting the powder, In order to prevent the particles from scattering, a granulated material having a larger particle size than the iron compound powder as the raw material, that is, a granulated material of the iron compound powder is supplied to the transport container. At this time, the particle size of the granulated product is not particularly limited, but preferably has a weight average particle size of 1 to 2 Omm, more preferably 2 to 1 Omm. It is preferably l mm or more from the viewpoint of suppressing the fluidization of the granulated material during gas supply, and is preferably 2 Omm or less from the viewpoint of keeping the diffusibility of the reducing gas and generated steam in the granulated material good. . When the granulated material is fluidized, fine powder is generated and the granulated material tends to jump out of the transport container. In addition, if the diffusivity of the gas in the granulated material deteriorates, the reduction tends to be uneven.

The method of granulating the iron compound powder is not particularly limited, and a known method is used. For example, a stirring tumbling granulation method, a flow granulation method, an extrusion granulation method, a crushing granulation method and the like can be mentioned.

As the reducing gas, pure hydrogen gas, CO gas, or a mixed gas containing an inert component therein can be used, but pure hydrogen gas is preferably used.

The preferred gas flow rate of the reducing gas depends on the particle size of the granulated iron compound powder, but is preferably 10 cm, sec or more in the gas linear velocity in the direction perpendicular to the gas flow surface (bottom surface) of the transfer container. It is more preferably at least 30 cmZ seconds, particularly preferably at least 5 Ocm / second. From the viewpoint of suppressing the partial pressure of steam generated by the reduction reaction, the gas linear velocity is preferably 10 cmZ seconds or more. When the partial pressure of water vapor increases, the size of the crystallites (X-ray crystal grain size) of metallic iron constituting the acicular shaped particles, which are the primary particles, becomes too large, resulting in deformation of the acicular shape and the interstices between the shaped particles. Sintering occurs, and the magnetic properties of the finally obtained magnetic metal powder tend to decrease. The gas linear velocity is the velocity at the reduction temperature.

The layer thickness of the granulated iron compound powder in the transport container is not particularly limited, but is preferably 25 cm or less, more preferably 20 cm or less. When the layer becomes thicker, the granulated iron compound powder on the gas discharge side in the transport container is reduced by hydrogen gas containing more water vapor generated on the gas supply side, and as a result, the gas discharge side The X-ray crystal grain size of the reduced product may increase and the magnetic properties may decrease, which is not preferable. Further, the reduction rate on the gas discharge side may decrease, and the reduction may become uneven. Even if the gas linear velocity of the reducing gas is increased, the effect of the partial pressure of water vapor on the gas discharge side cannot be ignored if the layer thickness is large. From this viewpoint, the layer thickness is

It is preferably 25 cm or less.

The reduction temperature is not particularly limited, and may be a commonly-known temperature range. For example, it is preferably from 300 to 700 ° C, more preferably from 350 to 600 ° C. The temperature is preferably at least 300 ° C. from the viewpoint of sufficiently reducing the iron compound powder to obtain a reduction product having effective magnetic properties, and is preferably at most 700 ° C. from the viewpoint of suppressing the collapse of the needle-like shape of the skeleton particles. When the needle-shaped collapse of the skeleton particles occurs, the magnetic properties tend to decrease.

The residence time of the iron compound powder granules in the reactor body, that is, the time from when the transfer container on which the iron compound powder granules are placed to the reactor body to when it leaves the reactor body (from the reduction time) ) Is preferably 0.5 to 10 hours, more preferably 1 to 8 hours, depending on the above conditions. The time is preferably 0.5 hours or more from the viewpoint of sufficient reduction, and 10 hours or less from the viewpoint of productivity. In the case where the processing is performed while transferring the transport container, such a residence time can be usually adjusted by changing the transport speed of the transport container by drive control of the transport unit or the like.

In the reduced product thus obtained, the transfer and the reduction reaction are performed in a state where the individual granulated material is substantially stationary, so that the shape of the granulated material used for the reduction reaction is substantially maintained as it is. I have. Such a reduced product may be used as it is as a metal magnetic powder, or may be powdered by a known method to obtain a metal magnetic powder.

The magnetic metal powder obtained in this way is chemically unstable and undergoes rapid oxidation in air, which significantly impairs its magnetic properties. It is more preferable to do so. For example, the metal magnetic powder may be immersed in toluene and then air-dried in the air. Since the reduced product is carried out of the furnace while being placed in the transport container, the reduced product is carried into a gas flow type reactor similar to the reactor used in the above-described reduction step, and is reduced by gas phase oxidation. By performing the stabilization process, a metal magnetic powder can be efficiently produced.

2) Aspect 2

In this embodiment, the reduced product obtained in the step (A) is carried out of the furnace while being placed in the transport container, and in the step (B), the reduced product is placed in the transport container while remaining in the transport container. Then, since the granulated material is subjected to gas phase oxidation while maintaining its shape, a stabilized metal magnetic powder can be efficiently produced.

Suitable manufacturing apparatuses used in this embodiment include, for example, a heating reduction reactor having a reducing gas supply means, a transfer container having a structure capable of flowing gas, and loading the transfer container into the heating reduction reactor. Transfer means for carrying out after the heat-reduction treatment, wherein the granules of the iron compound powder containing iron oxide hydroxide and Z or iron oxide as a main component placed in the transfer container are provided in the presence of a reducing gas. A heating gas-phase oxidation reactor having an oxygen-containing gas supply means, and a transfer container unloaded from the heating-reduction reactor to the heating gas-phase oxidation reactor. And a transfer means for carrying in after carrying out the gas-phase oxidation treatment and carrying out the gas-phase oxidation treatment, and a production apparatus provided with a device having a structure for performing a gas-phase oxidation of the reduced product heated and reduced in the presence of an oxygen-containing gas.

FIG. 5 is a schematic explanatory view of an example of a production apparatus suitable for the method for producing a metal magnetic powder of the present embodiment. As shown in the figure, this production system is configured by connecting a heating reduction reactor 61 and a heating gas phase oxidation reactor 62 in series, and between the respective reactors, unloads from the heating reduction reactor 61. It is connected via a transfer means 63 for carrying the transfer container 12 on which the reduced product is placed into the heated gas-phase oxidation reactor 62. The transfer means 63 is not particularly limited as long as the reduced matter in the transfer container 12 is not directly in contact with the atmosphere, and is capable of transferring the reduced matter in a stationary state. Except for using an oxygen-containing gas as the gas, the heated gas-phase oxidation reactor 62 can be a gas-flow reactor having substantially the same structure as the thermal reduction reactor of Embodiment 1 which is a gas flow type reactor. . With such a structure As a result, the reduced product is oxidized in the gas phase in the presence of the oxygen-containing gas. Various processing conditions in the step (A) are the same as the processing conditions for the reduction reaction in the first embodiment. The same applies to the raw material used in the present embodiment and the granulated material placed in the transport container as in the first embodiment.

Next, the step (B) will be described.

The oxygen-containing gas used in the present embodiment includes, for example, a mixed gas of oxygen or air and an inert gas. The inert gas is a gas that does not substantially react with the reduced product obtained in the step (A) under the contact treatment conditions, and specifically, N ₂ , He, Ne, Ar, C 0 _2, and the like. These may be used alone or in combination. The oxygen concentration in the oxygen-containing gas is preferably 100 to 250 ppm,

50-200 ppm is more preferred. The oxygen concentration is preferably 100 ppm or more from the viewpoint of promptly performing the gas phase oxidation treatment, and 250% from the viewpoint of suppressing the occurrence of a rapid oxidation reaction.

O ppm or less is preferred. When a rapid oxidation reaction occurs, the reaction temperature rises, and it may be difficult to maintain a predetermined temperature range.

The preferred gas flow rate of the oxygen-containing gas depends on the particle size of the granulated product, the reduced product obtained in step (A), but the gas linear velocity in the direction perpendicular to the gas flow surface (bottom surface) of the transfer container. Is preferably 5 cm, second or more, more preferably 10 cm, second or more, and particularly preferably 15 to 100 cmZ second. The gas linear velocity is the velocity at the gas phase oxidation temperature. The gas linear velocity is preferably 5 cm / sec or more from the viewpoint of exhibiting the effect of removing the reaction heat due to the gas flow and suppressing the occurrence of gas drift.

If the effect of removing the reaction heat is small, it is difficult to keep the reaction temperature constant, the reaction heat is partially accumulated, and only a certain part becomes high temperature, and the saturation magnetization may be reduced more than necessary. If gas drift occurs, it may not be oxidized and some parts may be formed. As a result, a metal magnetic powder having a very variable saturation magnetization is obtained. In some cases, when taken out into the atmosphere, the unoxidized portion generates heat or ignites due to a rapid oxidation reaction, and the inherently preserved material is retained. Significant loss of magnetic force and saturation magnetization It is not preferable because of fear.

The gas phase oxidation temperature is not particularly limited, and may be a known temperature range usually used. For example, the temperature is preferably from 40 to 150 ° C, more preferably from 50 to 130 ° C. Particularly preferably, it is 50 to 100 ° C. The gas phase oxidation temperature is preferably 40 ° C. or higher from the viewpoint of sufficiently performing surface oxidation, and is preferably 150 ° C. or lower from the viewpoint of suppressing excessive surface oxidation. If the surface oxidation is not sufficiently performed, the obtained metal magnetic powder may ignite when taken out to the atmosphere. If surface oxidation proceeds more than necessary, high saturation magnetization may not be obtained.

Further, since the saturation magnetization of the metal magnetic powder after the gas phase oxidation is uniquely determined by the gas phase oxidation temperature which is the reaction temperature in this step, the gas phase oxidation temperature is set according to the desired saturation magnetization. It is necessary to maintain a substantially constant temperature within the range. Here, the substantially constant temperature means ± 5 ° C. If the gas phase oxidation temperature fluctuates beyond ± 5 ° C., it may be difficult to obtain a metal magnetic powder having a desired saturation magnetization.

The residence time of the reduced product in the main body of the heated gas-phase oxidation reactor, that is, the time (stabilization time) from the time when the transport container on which the reduced product is loaded is carried into the reactor body to the time when the reduced product exits through the exit port is as described above. Although it depends on the above conditions, it is preferably 1 to 20 hours, more preferably 1.5 to 18 hours. The residence time is preferably 1 hour or more from the viewpoint of sufficiently performing the stabilization treatment by gas phase oxidation, and is preferably 20 hours or less from the viewpoint of production efficiency. When processing while transporting the transport container, such a residence time can usually be adjusted by changing the transport speed of the transport container by drive control of the transport means or the like.

Further, the transfer may be continuous transfer or intermittent transfer. Considering the production efficiency, in this embodiment, the transfer container is transferred in the heating reduction reactor while the granules of the iron compound powder are reduced by heating, and the transfer container is transferred in the heating gas phase oxidation reaction furnace and reduced. An embodiment in which the substance is oxidized in the gas phase is more preferable.

The oxide obtained in this way is transported with the individual granules substantially stationary. Since the reduction reaction and the gas phase oxidation reaction are performed, the shape of the granulated material when subjected to the reduction reaction is substantially maintained. Such an oxide may be used as it is as a metal magnetic powder, or may be powdered by a known method to obtain a metal magnetic powder.

The raw material for the reduction step used in Embodiments 1 and 2 is an iron compound powder containing iron oxide hydroxide and / or iron oxide as a main component as described above. When iron oxide is used, hydrated iron oxide can be heated and dehydrated to form iron oxide. In the present invention, by performing this heating and dehydration step using the same gas flow type reaction furnace as that used in the above-described reduction step and gas phase oxidation step, the metal magnetic powder can be efficiently and continuously produced. Can be manufactured.

3) Aspect 3

In this embodiment, the heating and dehydrating step of heating and dehydrating the hydrated iron oxide to form iron oxide is performed in a variety of ways, using a gas flow type reactor similar to the reactor used in the reduction step and the gas phase oxidation step of Embodiment 2. By doing so, the metal magnetic powder can be efficiently and continuously produced.

As a preferable production apparatus used in the present embodiment, for example, a production apparatus of metal magnetic powder in which a heating dehydration reaction apparatus, a heating reduction reaction apparatus, and a heating gas phase oxidation reaction apparatus are connected in this order. A heating / dehydration reactor having a non-reducing gas supply means, a transport container having a structure capable of flowing gas, and carrying the transport container into the thermal dehydration reactor, A transfer means for unloading after the treatment, wherein the heating and reducing reaction apparatus has a heating and reducing reaction furnace having a reducing gas supply means, and a transfer container unloaded from the heating and dehydrating reaction furnace is loaded into the heating and reduction reaction furnace. A heating gas-phase oxidation reactor having an oxygen-containing gas supply means, and a transfer container carried out of the heating-reduction reactor. The heated gas phase oxidation A transfer means for carrying in the furnace and carrying it out after the gas-phase oxidation treatment, wherein the granulated iron compound powder containing iron oxide hydrous as a main component is sequentially heated and dehydrated in the presence of a non-reducing gas to reduce Heat reduced in the presence of gas and in the presence of oxygen containing gas There is a manufacturing apparatus characterized by having a structure in which gas phase oxidation is performed. FIG. 6 is a schematic explanatory view of an example of a production apparatus suitable for the method for producing a metal magnetic powder of the present embodiment. As shown in Fig. 6, this production system is configured by connecting these reactors in series in the order of heating dehydration reactor 13, heating reduction reactor 14, heating gas phase oxidation reactor 15. Between the reactors, the transfer means 16 for carrying the transport container 12 loaded with the heated dehydrated product from the heating dehydration reactor 13 to the heating reduction reactor 14, and the heating reduction reactor 1 It is connected via a transfer means 17 for carrying the transfer container 12 carrying the reduced product, which is carried out from 4, on which the reduced product is placed, into the heated gas-phase oxidation reactor 15. The transfer means 16 and the transfer means 17 have a structure in which the heated dehydrated product and the reduced product in the transfer container 12 do not come into direct contact with the atmosphere, and can transfer the heated dehydrated product and the reduced product in a stationary state. There is no particular limitation. The thermal dehydration reactor 13 is a gas flow type reactor except that a non-reducing gas is used as a gas. The thermal reduction reactor of Embodiment 1 or 2 is substantially the same as the heating gas phase oxidation reactor. Those having a simple structure can be used. With such a structure, the granulated iron compound powder is subjected to heat dehydration, heat reduction, and heat gas phase oxidation.

Various processing conditions in each step are the same as those in steps (A) and (B) of Embodiment 2 in steps (D) and (E), and thus step (C) will be described.

The raw material used in this embodiment is an iron compound powder containing hydrous iron oxide as a main component. Specifically, the raw materials described in the first embodiment can be used. Also in this embodiment, a granulated iron compound powder obtained by granulating an iron compound powder as in Embodiments 1 and 2 is supplied to a transport container. The particle size and the like of the granulated product are the same as those in the first and second embodiments.

The non-reducing gas used is not particularly limited as long as it has no reducing power, and examples thereof include air and an inert gas. As the inert gas _{N 2, H e, N e} , A r, C 0 2 , and the like. These may be used alone or as a mixture.

The preferred gas flow rate of the non-reducing gas depends on the particle size of the granulated iron compound powder. However, the gas linear velocity in the direction perpendicular to the gas flow surface (bottom surface) of the transfer container is preferably 2 cmZ seconds or more, more preferably 10 cm, seconds or more. The gas linear velocity is the velocity at the heating dehydration temperature. From the viewpoint of suppressing the partial pressure of steam generated by the dehydration reaction, the gas linear velocity is preferably 2 cmZ seconds or more. If the partial pressure of water vapor increases, the size of the needle-like iron oxide crystallites (X-ray crystal grain size) that forms the heat dehydrated skeleton particles becomes too large, causing the needle-like shape to deform and form Sintering may occur, and the magnetic properties of the finally obtained magnetic metal powder may deteriorate.

The layer thickness of the granulated product in the transport container is preferably 25 cm or less, more preferably 20 cm or less. When the layer becomes thicker, the iron compound powder granules on the gas discharge side in the transport container undergo heat dehydration with a non-reducing gas containing more water vapor generated on the gas supply side, and as a result, the gas The needle-like shape of the skeleton particles of the heated dehydrated substance on the discharge side may deteriorate, which may cause the magnetic properties of the finally obtained magnetic metal powder to deteriorate.

The heating and dehydrating temperature is preferably from 350 to 700 ° C, more preferably from 400 to 650 ° C. The temperature is preferably 350 ° C. or higher from the viewpoint of sealing off the dewatering holes formed in the skeleton particles during dehydration. The temperature is preferably 700 ° C. or less from the viewpoint of suppressing the collapse of the needle-like shape of the skeleton particles. If the dewatering holes are not sealed or if the needle-like shape of the skeleton particles collapses, the magnetic properties of the finally obtained magnetic metal powder may deteriorate.

The residence time of the granulated iron compound powder in the thermal dehydration reactor main body, i.e., from the time when the transfer container on which the granulated iron compound powder is loaded is loaded into the reactor main body to the time when it is removed from the outlet. The time (heating dehydration time) is preferably 0.5 to 5 hours, more preferably 0.5 to 2 hours, depending on the above conditions. The time is preferably 0.5 hours or more from the viewpoint of sufficient heat dehydration, and preferably 5 hours or less from the viewpoint of production efficiency. In the case where the processing is performed while transporting the transport container, such a residence time can usually be adjusted by changing the transport speed of the transport container by drive control of the transport unit or the like. Further, the transfer may be continuous transfer or intermittent transfer. In consideration of production efficiency, in this embodiment, the transfer container is transferred in the heating and dehydration reactor while the granulated iron compound powder is heated and dehydrated, and the transfer container is transferred in the heating and reduction reaction furnace and dewatered by heating. More preferably, the reduced product is heated and reduced, and the reduced product is vapor-phase oxidized while transferring the transfer container in a heated gas-phase oxidation reactor.

The oxide obtained in this manner is used when the individual granules are transported in a substantially stationary state and subjected to a thermal dehydration reaction, a reduction reaction, and a gas phase oxidation reaction, so that they are subjected to the thermal dehydration reaction. The shape of the granulated material is substantially maintained. Such an oxide may be used as it is as a metal magnetic powder, or may be powdered by a known method to obtain a metal magnetic powder.

By using the manufacturing method and the manufacturing apparatus of the present embodiment as described above, when transferring the heated dehydrated product from the heating dehydration reactor to the heating reduction reactor, the heated dehydrated product is transferred in a substantially stationary state in the transport container. Therefore, the shape of the granulated material of the thermally dehydrated product can be maintained. As a result, the reduction reaction and the gas phase oxidation reaction can be performed uniformly, and a suitably stabilized metal magnetic powder can be produced.

In addition, a granulated iron compound powder, a heated dehydrated product that retains the shape of the granulated product, and a reduced product that retains the shape of the granulated product are heated and dehydrated in a substantially stationary state in a transport container. Treatment and gas-phase oxidation treatment, so that there is no collision between granules and no generation of fine powder, and because the shape of the granules is maintained, the contact between the object to be treated and the gas Good, uniform and excellent magnetic magnetic metal powder can be industrially advantageously produced. Example 1 (Example of reduction device)

FIG. 7 is a longitudinal sectional view showing an example of the heating and reducing reaction furnace, and FIG. 8 is a sectional view of the manufacturing apparatus.

The size of the reactor body 3 1 is 75 Omm in width, 100 mm in height, and 350 m in length m. As the heating means, an electric furnace system using an electric heater 34 for heating and a heat insulating material 35 is adopted.

The transfer container 33 is an open-top container having a bottom surface of 50 mm square and a height of 200 mm. The bottom surface of the transfer container 33 is formed of a mesh having a diameter of 0.5 mm so that gas can flow. The opening ratio of the transfer container is 40%. The reactor body has a cross-sectional shape as shown in FIG.

Then, the transfer container 33 is transferred by a drive roller 36 and a drive motor 51 provided outside the reactor main body. The driving mechanism has a mechanism capable of variably controlling the number of rotations of the motor, and the transfer container can be transferred by appropriately controlling the roller rotation speed. The roller drive shaft 52 is provided with a shaft seal 50 for sealing the reducing gas.

The gas dispersion plate 32 is a perforated plate having a cross section of 5110 × 510 mm. Five gas dispersion plates are installed in the reactor. In addition, as shown in FIG. 8, a gas seal wall 53 is provided so that the reducing gas ejected from the gas dispersion plate effectively flows through the inside of the object to be processed mounted on the transfer container.

The object to be processed is placed on the transfer container 33 from the supply hopper 37 shown in FIG. The transfer container 33 on which the object is placed is carried into the reaction furnace from the carry-in port 38. The carry-in entrance has a structure that has a door that shuts off gas, and the door is opened only while the transfer container is carried into the reaction furnace.

The object to be treated carried into the reactor is reduced by coming into contact with the reducing gas introduced from the inlet 40 of the reducing gas into the main body of the reactor and ejected from the gas dispersion plate 32. The transport container is moved in the direction of arrow A by one drive roller. In addition, reducing gas is discharged from the gas outlet 41.

The transfer container on which the metal magnetic powder obtained after the completion of the reduction reaction of the object to be processed is transferred to the outside of the reaction furnace from the discharge port 39. The carry-out port has a structure similar to the carry-in port 38 and has a door for shutting off gas, so that the carry-out port is carried out only while the carry-out container is carried out of the reactor. Open the door.

The driving time of the roller is controlled by the residence time of the object in the reactor (the time from when the object is loaded into the reactor body to when it is unloaded from the outlet 39), that is, the reduction time. Adjust with.

(Example of reduction production)

The object to be treated is a needle-shaped crystal grain having 4 parts by weight of A1 with respect to 100 parts by weight of Fe, and a primary particle having a major axis length of 0.22 m and an axial ratio of 10. Granules having a diameter of about 3 mm obtained by granulating Fe OOH by an extrusion granulation method were used. This was reduced at 500 ° C. using hydrogen gas by the production apparatus shown in Example 1. Hydrogen gas flowed so that the gas linear velocity downward and perpendicular to the gas flow surface of the transfer container was 60 cm / sec. The specific operation is as follows.

10 kg of the above-mentioned granulated iron compound powder, which is an object to be treated, was placed on the transfer container 33 from the supply hopper 37. At this time, the layer height of the object to be treated was 10 cm. The transfer container on which the object was placed was transferred from the loading port 38 into the reactor every 36 minutes. The granulated material transferred into the reactor was reduced while being in contact with the hydrogen gas blown from the gas dispersion plate 32. The transport container on which the object was placed was transferred by the drive roller 36 to the next dispersion plate in the direction of arrow A every 36 minutes. The reduction time of the object was 3 hours.

Under the above manufacturing conditions, 6.2 kg of metal magnetic powder could be obtained per transfer container. A part of the metal magnetic powder is immersed in toluene, then air-dried in the air to oxidize the surface, and the magnetic properties are measured by X-ray crystal particle size (VSM) using a sample vibration magnetometer (VSM). The crystallite size of metallic iron was measured using an X-ray diffractometer. At this time, the X-ray crystal grain size was determined from the half width of the iron (110) diffraction peak of X-ray diffraction using the Schiller equation.

As a result, the obtained metal magnetic powder has a coercive force (He): 1610 [O e] Sum magnetization (as): 142 Cemu / g), squareness ratio (bi rZ bi s): 0.50 [1], X-ray crystal grain size 18 1 CA), and excellent magnetic properties Was something.

Example 2 (Example of reduction + gas phase oxidation apparatus)

As shown in FIG. 5, the production apparatus of this embodiment is configured by connecting a heating reduction reactor 61 and a heating gas phase oxidation reactor 62 in series. The transfer of the transfer container from the heat-reduction reactor 61 to the heat-gas-phase oxidation reactor 62 is performed by a driving α-roller under a nitrogen atmosphere so as not to come into contact with the air. That is, while the object to be processed is carried into the heated gas-phase oxidation reactor 62 from the heat-reduction reactor 61, the object can be kept stationary in the transfer container. As the thermal reduction reactor 61, the gas flow type reactor of Example 1 is used. The heating gas-phase oxidation reactor 62 has a reactor body length of 1100 mm, employs a steam trace as a heating means, and has 15 gas distribution plates in the reactor. Except for the installation, the same furnace as the gas-flow reactor used as the heating reduction reactor in Example 1 is used.

(Production example of reduction + vapor phase oxidation)

As the object to be treated, the same one as in Example 1 was used. This was subjected to processes (A) and (B) using the manufacturing apparatus of Example 2 under the following conditions.

[Step (A)]

Using the apparatus of Example 1, a reduced product was produced in the same manner as in Example 1.

[Step (B)]

An air-nitrogen mixed gas containing 100 ppm of oxygen was used as the oxygen-containing gas, and the gas phase oxidation treatment was performed at 70 ° C. This oxygen-containing gas was allowed to flow so that the gas linear velocity vertically downward with respect to the gas flow surface of the transport container was 40 cm / sec. Specific operations are shown below. The reduced product carried out by the driving roller 1 under the nitrogen atmosphere from the step (A) maintained its granulated shape in the transport container, and was sent to the heated gas-phase oxidation reactor in that state.

The transport container on which the reduced product was placed was transferred from the entrance to the heated gas-phase oxidation reactor every 36 minutes. The reduced product transferred into the heated gas-phase oxidation reactor was subjected to a gas-phase oxidation treatment while being in contact with the oxygen-containing gas blown from the gas dispersion plate. The transport container on which the reduced product was placed was transferred to the next dispersion plate by a driving roller every 36 minutes. The residence time of the reduced product in the heated gas-phase oxidation reactor was 9 hours. The transport container on which the reduced product subjected to the gas phase oxidation treatment was placed was carried out of the reactor from the outlet every 36 minutes. Under the above manufacturing conditions, 6.7 kg of metal magnetic powder was obtained per transfer container.

When the magnetic properties and the X-ray crystal grain size of the metal magnetic powder were measured in the same manner as in Example 1, the coercive force (He): 159 [O e], the saturation magnetization (CTS): 121 Cemu Zg], squareness ratio ((T rZ s): 0.50 [1], X-ray crystal grain size of 1172 CA), and the metal magnetic powder obtained by the production method of the present invention has a granulated shape. Had been maintained. Further, after the surface of the metal magnetic powder obtained in the step (B) is adsorbed with 1.0 part by weight of water with respect to 100 parts by weight of the metal magnetic powder, the metal magnetic powder is added to the powder. I took it out. Then, no sudden heat generation was observed in the metal magnetic powder, and it was found that stabilization was suitably performed in the step (B). Example 3

[Step (A)]

Except that the transfer container on which the object is placed is placed in the heating reduction reactor of Example 1 and is stopped in the furnace, and the reaction is performed for 3 hours without transferring the transfer container. Produced a reduced product in the same manner as in Example 1.

After the step (A) is completed, the reduced product carried out by the driving roller under a nitrogen atmosphere maintains its granulated shape in the transfer container, and is sent to the heated gas-phase oxidation reactor in that state.

[Step (B)]

The transfer vessel on which the reduced product obtained in step (A) is placed is transported into the heated gas-phase oxidation reactor, and is stopped in the furnace, and the reaction is performed for 9 hours without transferring the transfer vessel. Except that the gas-phase oxidation treatment was performed in the same manner as in Example 2.

After the completion of the step (B), the transfer vessel on which the reduced product subjected to the gas phase oxidation treatment was carried out of the reactor, and 6.7 kg of metal magnetic powder was obtained per transfer vessel.

When the magnetic properties and the X-ray crystal grain size of the metal magnetic powder were measured in the same manner as in Example 1, the coercive force (He): 158 0 [Oe], the saturation magnetization (crs): 120 [emu / g, squareness ratio (rZ rs): 0.50 [1], X-ray crystal grain size: 173 CA), and the metal magnetic powder obtained by the production method of the present invention maintained a granulated shape. . Further, after the surface of the metal magnetic powder obtained in the step (B) is adsorbed with 1.0 part by weight of water with respect to 100 parts by weight of the metal magnetic powder, the metal magnetic powder is added to the powder. I took it out. As a result, no rapid heat generation was observed in the metal magnetic powder, and it was found that the metal magnetic powder was suitably stabilized in the step (B). Comparative Example 1

The granulated material is continuously supplied and placed on a belt, and while the granulated material is transferred, a reduced product is obtained by a heat reduction treatment with hydrogen gas to obtain a reduced product. The production described in Examples 1 and 4 of US Patent No. 5 470 3 74 (FIGS. 1, 2, 3, and 5 of the patent publication) in which metal magnetic powders are continuously obtained by a gas phase oxidation treatment using a contained gas. Using the apparatus, the processes of step (A) and step (B) were performed under the following conditions. As the object to be treated, the same one as in Example 1 was used. [Step (A)]

The hydrogen gas was circulated so that the gas linear velocity vertically upward to the mesh belt surface was 60 cmZ seconds, and the powder feeder was supplied at a supply speed of 8.O kgZ time. The same manufacturing method as described in Example 2 of US Patent 54 70 374 was used except that the thickness was adjusted with a thickness adjusting plate so that the layer thickness became 10 cm, and the heat reduction treatment was performed at 500 ° C. 4. 9 k hours of reduced product was obtained.

As shown in Fig. 5 of USP atent 54 70 374, this reduced product is transferred from the heat reduction reactor to the heated gas phase oxidation reactor via a storage tank, and cannot retain the granulated shape. Most of them were atomized when they were supplied to the thermal reduction reactor.

[Step (B)]

A mixed gas of air and nitrogen containing 100 ppm of oxygen is flowed so that the gas linear velocity upward and perpendicular to the mesh belt surface is 40 cmZ seconds, and 4 The above-mentioned reduced product was continuously supplied at a rate of 9 kg / hour into the heated gas-phase oxidation reactor body heated to the gas-phase oxidation temperature so that the residence time in the heated gas-phase oxidation reactor was 9 hours. Except for adjusting the running speed of the belt, 4.9 kg / hr of metal magnetic powder was obtained by the same manufacturing method as described in Example 5 of US Patent 5,470,374.

A part of the metal magnetic powder was extracted, and the magnetic properties and the X-ray crystal grain size of the metal magnetic powder were measured in the same manner as in Example 1. The coercive force (He): 160 [〇e] The saturation magnetization (as) was 128 Cemu / g), the squareness ratio (σr / s) was 0.50 [1], and the X-ray crystal grain size was 176 [A].

Further, after the surface of the metal magnetic powder obtained in the step (B) is adsorbed with 1 part by weight of water based on 100 parts by weight of the metal magnetic powder, the metal magnetic powder is exposed to the air. I took it out. Then, the metal magnetic powder partially lacked the stabilization treatment. Because of the rapid heat generation, it oxidized, and most of the metal magnetic powder turned into iron oxide. Example 4 (Example of dehydration + reduction + gas phase oxidation equipment)

As shown in FIG. 6, the manufacturing apparatus of the present embodiment is configured by connecting a heating dehydration reactor 13, a heating reduction reactor 14, and a heating gas phase oxidation reactor 15 in series. The transfer means 16 and the transfer means 17 are provided via a drive roller in a nitrogen atmosphere. As the thermal dehydration reactor 13, the same gas flow type reactor as in Example 1 was used except that the reactor body was 250 Omm long and three gas dispersion plates were installed in the reactor. I have.

As the heat reduction reactor 14, the gas flow type reactor of Example 1 is used. Further, as the heated gas-phase oxidation reactor 15, the gas flow type reactor of Example 2 is used.

(Example of dehydration + reduction + gas phase oxidation production)

The material to be treated contains 3 parts by weight of Si and 5 parts by weight of C0 with respect to 100 parts by weight of Fe, and the primary particles have a major axis length of 0.25 m and an axial ratio of 1 A granulated material having a diameter of about 3 mm obtained by granulating acicular crystal FeOOH, which is 0, by an extrusion granulation method was used. This was subjected to the processes (C), (D) and (E) using the manufacturing apparatus of Example 4 under the following conditions.

[Process (C)]

In the step (C), a nitrogen gas was used as a non-reducing gas, and the above-mentioned object was heated and dehydrated at 500 ° C. Nitrogen gas was passed so that the gas linear velocity downward and perpendicular to the gas flow surface of the transport container was 15 cm / sec. The specific operation is shown below.

First, 1 O kg of the object to be processed was placed from the supply hopper 11 in FIG. At this time, the layer height of the object to be treated was 10 cm. The transport on which the object is placed The transport container was transferred from the loading port into the heating dehydration reactor 13 every 36 minutes. The object transferred into the reactor was dehydrated while being in contact with the nitrogen gas blown from the gas dispersion plate. The transport container on which the object was placed was transferred to the next dispersion plate by a driving roller every 36 minutes. The residence time of the object to be treated in the thermal dehydration reactor was 2 hours. The transfer container on which the object was placed was carried out of the heating / dehydration reactor from the outlet every 36 minutes. The transport container used in this example is the same as that in Example 1.

Under the above manufacturing conditions, 8.7 kg of heated dehydrated product was obtained per one transport container. The heated dehydrated product was sent to the step (D) by a driving porter under a nitrogen atmosphere while being kept still in the transfer container.

[Process (D)]

The heated dehydrated product obtained in the step (C) was subjected to a heat reduction treatment at 480 ° C. in a step (D) using hydrogen gas as a reducing gas. The hydrogen gas flowed so that the gas linear velocity downward and perpendicular to the gas flow surface of the transfer container was 60 cmZ seconds. The specific operation is shown below.

The transfer container on which the heated dehydrated product was placed was transferred into the heating reduction reactor from the loading port every 36 minutes. The heated dehydrated product transferred into the reactor was reduced while contacting the hydrogen gas blown from the gas dispersion plate. The transport container on which the reduced matter was placed was transferred to the next dispersion plate by the driving roller 1 every 36 minutes. The residence time of the heat dehydration product in the heat reduction reactor was 3 hours. The transport container on which the reduced product was placed was carried out of the reactor from the outlet every 36 minutes.

Under the above production conditions, 6.2 kg of reduced product was obtained per one transport container. This reduced product was sent to the step (E) by a driving roller 1 under a nitrogen atmosphere while being kept still in the transfer container.

The magnetic properties and X-ray crystal grain size of the reduced product obtained in the step (D) were measured in the same manner as in Example 1. The coercive force (He): 1630 [Oe], saturation Magnetization (σ s ): 144 [emu / g], squareness ratio (rZ and s): 0.49 [1], and X-ray crystal grain size: 177 CA).

[Step (E)]

As the oxygen-containing gas, an air / nitrogen mixed gas containing 100 ppm of oxygen was used, and a gas phase oxidation treatment was performed at 75 ° C. The oxygen-containing gas was flowed so that the gas linear velocity vertically downward with respect to the gas flow surface of the transport container was 40 cmZ seconds. The reduced product carried out from the heated gas-phase oxidation reactor by a driving roller under a nitrogen atmosphere was sent to the heated gas-phase oxidation reactor while maintaining its granulated shape in a transport container.

The transport container on which the reduced product was placed was transferred from the entrance to the heated gas-phase oxidation reactor every 36 minutes. The reduced product transferred into the heated gas-phase oxidation reactor was subjected to a gas-phase oxidation treatment while being in contact with the oxygen-containing gas blown from the gas dispersion plate. The transport container on which the reduced product was placed was transferred to the next dispersion plate every 36 minutes by a drive port. The residence time of the reduced product in the heated gas-phase oxidation reactor was 9 hours. The transport container on which the reduced product subjected to the gas phase oxidation treatment was carried out of the reactor from the outlet every 36 minutes. Under the above manufacturing conditions, 6.7 kg of metal magnetic powder was obtained per transfer container.

A part of the metal magnetic powder was extracted, and the magnetic properties and the X-ray crystal grain size of the metal magnetic powder were measured in the same manner as in Example 1. The coercive force (He): 165 COe] The saturation magnetization (bi s): 120 [emu / g], the squareness ratio (σ r / bi s): 0.49 [1], and the X-ray crystal grain size: 16 9 [A]. The metal magnetic powder obtained by the production method maintained the granulated shape. Also, after the surface of the metal magnetic powder obtained in the step (E) is adsorbed with 1 part by weight of water with respect to 100 parts by weight of the metal magnetic powder by a conventional method, the metal magnetic powder is placed in the air. I took it out. As a result, no sudden heat generation was observed in the metal magnetic powder, and the metal magnetic powder was suitably stabilized in step (E). Industrial applicability

According to the first aspect, the granulated iron compound powder can be reduced and carried out in a substantially stationary state, so that the shape change of the skeleton particles due to the collision of the particles during the reduction and the influence of the generated water vapor and the morphology particles are caused. During the sintering, a metal magnetic powder having excellent magnetic properties can be obtained while maintaining the shape of the granulated product.

According to the second aspect, since the granulated product or reduced product of the iron compound powder can be subjected to the heat reduction or the gaseous phase oxidation treatment in the transport container in a substantially stationary state, and further, can be transferred in a substantially stationary state. , Collision between particles during the reaction and transfer ゃ no generation of fine powder, good contact of the gas with the granulated and reduced products of iron compound powder, and uniform and excellent magnetic magnetic powder Can be manufactured.

According to the third aspect, the granulated material, the thermally dehydrated product, or the reduced product of the iron compound powder is subjected to thermal dehydration, thermal reduction, or gas phase oxidation treatment in a substantially stationary state in a transport container, and further substantially stationary. Since the particles can be transferred in a state, they do not collide with each other during the reaction and transfer, and no fine powder is generated.In addition, the contact of the gas with the granulated, heated dehydrated and reduced products of the iron compound powder is good, and uniform and excellent. Thus, a metal magnetic powder having excellent magnetic properties can be produced.

Claims

Scope of request 1. In a method for producing a metal magnetic powder in which iron compound powder containing iron oxide hydroxide and Z or iron oxide as a main component is heated and reduced in the presence of a reducing gas, the granulated iron compound powder is used. Is placed in a transfer container having a structure capable of gas flow, and the transfer container is carried into a heat reduction reaction furnace, and the granulated iron compound powder is heated and reduced in the presence of a reducing gas. Manufacturing method of magnetic powder.

2. Metallic magnetic powder obtained by heating and reducing an iron compound powder containing iron oxide hydroxide and / or iron oxide as a main component in the presence of a reducing gas, and subjecting the resulting reduced product to gas phase oxidation in the presence of an oxygen-containing gas. In the manufacturing method of

A method for producing a metal magnetic powder, comprising:

3. The iron compound powder containing hydrous iron oxide as a main component is heated and dehydrated in the presence of a non-reducing gas, and the resultant dehydrated product is reduced by heating in the presence of a reducing gas. In a method for producing a metal magnetic powder to be vapor-phase oxidized in the presence of a contained gas,

(D) The transfer container on which the heated dehydrated product obtained in the step (C) is placed is placed in a heating reduction reactor. Transporting the heated dehydrated product in the presence of a reducing gas to obtain a reduced product; and

A method for producing a metal magnetic powder, comprising:

4. The production method according to claim 1, wherein the granules of the iron compound powder are thermally reduced while being transferred in the heat reduction reaction furnace.

5. The iron compound powder granules are thermally reduced while transferring the transfer container in the heating reduction reactor, and the reduced product is oxidized in the gas phase while transferring the transfer container in the heating gas phase oxidation reactor. 2. The production method according to 2.

6. While transferring the transfer container in the heating and dehydration reaction furnace, the granulated iron compound powder is heated and dehydrated, and while the transfer container is transferred in the heating and reduction reaction furnace, the heated and dehydrated product is heated and reduced. 4. The production method according to claim 3, wherein the reduced product is subjected to gas phase oxidation while transferring the gas in a heated gas phase oxidation reactor.