JP2001110619A - Method for manufacturing ferrite magnetic powder and ferrite magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of ferrite magnetic powder, whose composition and grain size are uniform and fine. SOLUTION: There is included a process for manufacturing ferrite material powder by spraying mixed solution in which chloride of iron and chloride of strontium are dissolved, with a heating atmosphere. The mixed solution to be sprayed contains FeCl2 of at least 25% and at most 35% and SrCl2 of at least 2.4% and at most 4.4%. The powder particles formed by spraying has magnetoplumbite type hexagonal system crystal structure whose basic composition is expressed by SrO.nFe2O3 (5.0<=n<=6.5), and exhibit superior magnetic characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing ferrite magnetic powder and a ferrite magnet by a spray pyrolysis method. This ferrite magnet is suitably used for motors, speakers, and the like.

[0002]

2. Description of the Related Art Ferrite is a general term for a compound formed by a divalent cation metal oxide and a trivalent iron oxide. Ferrite magnets are used for various applications such as motors and generators. As a raw material of a ferrite magnet, Sr ferrite (S) having a magnetoplumbite-type hexagonal structure is used.
rFe ₁₂ O ₁₉ ) or Ba ferrite (BaFe ₁₂ O ₁₉ )
Is widely used.

[0003] The basic composition of magnetoplumbite ferrite is usually represented by the chemical formula "MO.nFe2O3". The element M is a metal that becomes a divalent cation,
It is selected from r, Ba, Pb, Ni and others. The iron ion (Fe3 +) at each site in the ferrite has a spin magnetic moment, and is linked by superexchange interaction via oxygen ions (O-2). At each Fe3 + site, the magnetic moment of Fe3 + is "up" or "down" along the c-axis. Number of sites with "up" magnetic moment and "down"
Therefore, the crystal as a whole exhibits ferromagnetism (ferrimagnetic material).

[0004] Magnetoplumbite type ferrite has been conventionally produced as follows.

First, iron oxide and a carbonate such as strontium (Sr) or barium (Ba) are used as raw materials and mixed at a predetermined molar ratio. This is calcined at a temperature of 1150 to 1400 ° C., and then pulverized by using a ball mill or the like to be powdered. This powder is formed into a predetermined shape and sintered.

[0006]

However, such a conventional manufacturing method has the following problems.

(1) Since the solid raw material mixed powder is mixed and dispersed, uniform mixing of the composition is not always sufficient, and the magnetic properties of the product do not reach a sufficient level.

(2) Since the calcination temperature is as high as 1150-1400 ° C., the cost increases.

(3) Since the magnetic powder grows in the calcining step,
It takes a long time to mechanically pulverize with a ball mill or the like down to 1 μm or less in the next pulverization step. At this time, mixing of impurities due to abrasion of the pulverization medium or a composition shift occurs. Problems such as the particle size distribution not being sharpened occur and the magnetic properties of the product deteriorate.

The present invention has been made in view of the above points, and a main object of the present invention is to provide a method for producing fine ferrite magnetic powder having a uniform composition and particle size.

Another object of the present invention is to provide a method for producing a ferrite magnet having excellent magnetic properties using the above ferrite magnetic powder.

[0012]

According to the present invention, there is provided a method for producing a magnetoplumbite-type ferrite magnetic powder, comprising: spraying a mixed solution in which a chloride of iron and a chloride of strontium are dissolved into a heated atmosphere to thereby reduce the ferrite raw material powder. A method for producing magnetoplumbite-type ferrite magnetic powder including a step of producing, wherein the mixed solution contains 25% to 35% by mass of FeCl ₂ (ferrous chloride), and 2.4% to 4%. .4% or less SrCl
₂ (Strontium chloride) is dissolved.

Another method for producing magnetoplumbite-type ferrite magnetic powder according to the present invention comprises a step of producing a ferrite raw material powder by spraying a mixed solution in which iron chloride and strontium chloride are dissolved in a heated atmosphere. A method for producing magnetoplumbite-type ferrite magnetic powder, wherein the mixed solution further contains a chloride of cobalt and a chloride of lanthanum.

The mixed solution contains 25% or more and 35% or less by mass of FeCl ₂ , 1.9% or more and 4.2% or less of SrCl ₂ , and 0.09% or more and 0.73% or less of CoC.
l ₂ , and 0.16% to 1.18% of LaCl ₃
Is preferably dissolved.

Preferably, a flammable solvent such as alcohol is mixed with the mixed solution.

The spraying of the mixed solution is preferably performed in a furnace at a temperature of 800 ° C. to 1300 ° C., and more preferably in a furnace at a temperature of 1000 ° C. to 1200 ° C.

Preferably, the concentration of FeCl _{2 in} the mixed solution is 27% or more and 33% or less.

As a raw material of the mixed solution, a waste liquid generated by pickling at an ironworks may be used.

The mixed solution may be sprayed by using a hydrochloric acid recovery device in the steel mill.

The method may further include a step of performing a heat treatment on the ferrite raw material powder.

Preferably, the heat treatment is performed at a temperature of 800 ° C. or more and 1200 ° C. or less.

More preferably, the heat treatment is performed at a temperature of 900 ° C. or more and 1050 ° C. or less.

A method for producing a ferrite magnet according to the present invention comprises the steps of: preparing a magnetoplumbite-type ferrite magnetic powder produced by any of the above-described methods for producing ferrite magnetic powder; and providing a sintered magnet using the ferrite magnetic powder. And a step of manufacturing a permanent magnet such as a bonded magnet.

Before the step of manufacturing the permanent magnet, the magnetoplumbite-type ferrite magnetic powder may be further finely pulverized.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors sprayed a mixed solution in which iron chloride and strontium chloride were dissolved in a heated atmosphere, whereby a fine magnetoplumbite hexagonal crystal having a uniform composition and particle size was obtained. Various experiments for producing ferrite magnet powder (magnetic powder) were performed. As a result, they have found that fine powder of hard ferrite having excellent magnetic properties can be obtained by adjusting the concentration of each chloride contained in the above mixed solution within an appropriate range.

The present inventors have also found that the powder produced by spraying may contain a phase (such as α-Fe ₂ O ₃ or SrCl ₂ ) other than ferrite crystals depending on various conditions such as a heating atmosphere temperature. Even when the powder contains such an unreacted phase (unferritized phase), if heat treatment is performed later in an appropriate temperature range, the powder particles have excellent magnetic properties while suppressing coarsening of the powder particles. It has been found that ferrite magnetic powder can be obtained. For this reason, in this specification,
Regardless of whether the powder produced by spraying contains phases other than ferrite crystals (such as α-Fe ₂ O ₃ or SrCl ₂ ) or not, the powder obtained by spraying is referred to as “ferrite. Raw material powder ".

When ferrite magnetic powder is produced by the spray pyrolysis method, various steps such as dispersion, dehydration, calcination, and pulverization can be omitted, so that productivity is improved and production cost is reduced. In addition, it is also possible to avoid problems such as mixing of foreign substances and deviation of the composition in the pulverizing step, and problems such as broadening of particle size distribution due to formation of ultrafine powder. Furthermore, in the mixed solution to be sprayed, the elements of iron and strontium are uniformly dispersed at the atomic level, so that the uniformity of the composition between the powder particles is improved, and as a result, the final magnet is obtained. The composition is also made uniform. In addition, the spraying produces fine powder particles having a submicron particle size, so that it is possible to shorten the time of the subsequent pulverization step or omit the pulverization step itself.

The basic composition of Sr ferrite produced by the method of the present invention is SrO.nFe ₂ O ₃ (5.0 ≦
It has a magnetoplumbite-type hexagonal structure represented by (n ≦ 6.5). As described above, the powder immediately after spraying may contain fine powder of an unreacted phase (such as α-Fe ₂ O ₃ or SrCl ₂ ). However, if heat treatment is performed later, the unreacted phase disappears and substantially disappears. Finally, all the powder particles have a magnetoplumbite type hexagonal structure.

When the above-mentioned Sr ferrite is formed, the mixed solution to be sprayed is FeCl ₂ : 25 to 35%, Sr
Cl _2: use 2.4 to 4.4% of water or hydrochloric acid solution.
The concentration of FeCl ₂ is more preferably from 27 to 32%, and the concentration of SrCl ₂ is more preferably from 3.0 to 3.7%.

In this specification, the notation “%” or “wt%” means “mass percentage of solute with respect to the mixed solution”, for example, “25 to 35%”.
Indicates "25% or more and 35% or less" in terms of mass percentage.

The Sr ferrite produced in the present invention has the above
It is not limited to those having the composition of
−x) SrO · (x / 2) La_TwoO_Three・ (Ny / 2) F
e_TwoO_Three・ Magneto plumbite type expressed by yCoO
It may have a hexagonal structure. here,
x, y and n represent a molar ratio, and 0.05 ≦ x ≦ 0.
2, 0.05 ≦ y ≦ 0.2, 5.0 ≦ n ≦ 6.5
You. In this case, the mixed solution is FeCl_Two: 25-
35%, SrCl_Two1.9-4.2%, LaCl _Three:
0.16 to 1.18%, CoCl_Two: 0.09 to 0.7
Use a 3% water or hydrochloric acid solution.

If necessary, the spray solution may contain B ₂ O ₃ or another compound such as Ca, Si, Al, Ga, In, or L.
i, Mg, Mn, Ni, Cr, Cu, Ti, Zr, G
A compound containing e, Sn, V, Nb, Ta, Sb, As, W, Mo, a rare earth element (including Y), or the like may be added. Further, the mixed solution may contain impurities such as unavoidable components as long as the amount is small.

When the above mixed solution is sprayed into a furnace such as a roasting furnace and heated, a flammable liquid such as alcohol (0 to 50) is used.
%) Is preferably mixed with the solution and sprayed.
Note that a flammable gas may be blown into the solution instead of adding the flammable liquid to the solution. Due to the addition of flammable substances, even if the ambient temperature in the furnace is relatively low,
It becomes easy to change the mixed solution into a form of magnetoplumbite-type Sr ferrite powder. However, if the content of the combustible substance is more than 50%, the chloride concentration in the mixed solution is relatively reduced, so that the powder particles generated by spraying are too fine. If the powder particles are too fine, it will be difficult to magnetically orient the powder particles even when performing wet press molding in a magnetic field. Further, since the grain growth occurs remarkably during sintering, the magnetic properties of the magnet product are deteriorated.

In addition, iron and strontium chlorides are mainly used.
Water or hydrochloric acid solution of mixed chloride as a component is 800 to 1
When sprayed into a roasting furnace at a relatively low temperature of about
Mag as raw material for Gnetoplumbite Sr ferrite
Netoprubite type Sr ferrite, iron oxide (α-Fe
_TwoO_Three) And / or strontium chloride (SrC
l _Two) Is liable to be formed. Such mixed powder
The powder is a magnetoplumbite with a particle size of 0.1 to 0.5 μm.
G type Sr ferrite and / or iron oxide (α-Fe_TwoO_Three)
Strontium chloride (SrCl_Two) Super fine particles
It has a structure in which children are dispersed. Because of this,
The mixed powder is at a normal calcining temperature (1150-1400 ° C).
Magnetoplan at lower temperature (800-1200 ° C)
Changes to bite type Sr ferrite powder.

The spray solution may be prepared by mixing the solution and a strontium chloride solution, but is prepared by directly dissolving a strontium raw material such as strontium carbonate and strontium chloride in a ferrous chloride solution. Then, it is efficient.

As the ferrous chloride solution, it is also possible to use a waste liquid produced when hydrochloric acid and pickling of a steel plate or the like is performed in a rolling process of an ironworks. The strontium chloride solution can be obtained by directly dissolving a strontium raw material such as strontium carbonate and strontium chloride in an aqueous ferrous chloride solution, and also by dissolving the strontium raw material in hydrochloric acid.

(1-x) SrO. (X / 2) La ₂ O _3.
(N-y / 2) when forming a ferrite Fe ₂ O ₃ · yCoO is lanthanum chloride, lanthanum oxide, cobalt chloride, cobalt oxide, lanthanum such as cobalt carbonate, and hydrochloric acid or an aqueous solution of ferrous chloride of cobalt material It should just dissolve in.

Incidentally, nitrate may be used as a raw material of the above iron, strontium, lanthanum and cobalt.

By spraying the aqueous solution of the mixed chloride or the hydrochloric acid solution using a hydrochloric acid recovery device at an ironworks, ferrite powder can be efficiently produced.

FIG. 1 is a cross-sectional view showing a schematic configuration example of a spray roasting furnace 10 used for producing a powder by spraying a mixed solution. The above mixed solution (Solution)
4 and blown into the interior 13 of the furnace 10. Furnace interior 1
The atmosphere gas of No. 3 is heated by a burner gas (shown by a thick arrow in the figure) introduced through the opening 12. The sprayed droplets of the mixed solution come into contact with a heated atmosphere (hot air), and are dried and thermally decomposed to form ferrite. The ferrite crystal powder 16 thus generated is taken out from the bottom 15 of the furnace interior 13. Water vapor, hydrochloric acid, ultrafine particles of ferrite powder, and the like generated in the furnace interior 13 by the ferrite-forming reaction are discharged out of the furnace through the exhaust port 11. In this example, a configuration is employed in which a burner gas is blown onto the atmosphere gas, thereby forming a vortex in the furnace interior 13.

In the furnace 10, a burner gas is used to heat the atmospheric gas, but an electric heater may be used instead. In addition, air may be used as the atmosphere gas.

[0042]

Embodiments of the present invention will be described below.

(Example 1) First, Sr in terms of oxide weight.
Ferrous chloride and strontium chloride were weighed to obtain O.5.8Fe ₂ O ₃ , and these were dissolved in pure water. At this time, the concentration of ferrous chloride was 29%. Ethanol was added to this solution and mixed well. The concentration of ethanol for the solution was 0, 20, 40, 50, and 6
0%.

The above solution was heated at an atmospheric temperature of 1 in the body.
The powder was sprayed into a spray roasting furnace at 000 ° C. to produce a powder. X
The material constituting the powder was identified using a line diffraction apparatus. As shown in Table 1, when ethanol was added to the solution, the obtained powder was almost magnetoplumbite type S
It can be seen that the ferrite was composed of a single ferrite phase.

[0045]

[Table 1]

The magnetic properties of the powder were measured using a VSM. Table 2 shows the measurement results. As can be seen from Table 2, the magnetic properties of the powder, especially the coercive force, are excellent.

Additives (CaCO ₃ : 0.9%, S
iO ₂ : 0.45%), and 45% using a pure water solvent.
A slurry liquid was prepared. After performing the mixing process for 1 hour in a wet ball mill, a sintering process was performed through a wet press molding process. Sintering was performed at a maximum sintering temperature of 1210 ° C. 2, the residual magnetic flux density of the thus obtained sintered body shows a (residual magnetization) B _r. As can be seen from FIG. 2, the amount of ethanol added to the solution is preferably 20% or more and 50% or less in terms of mass percentage.

Comparative Example 1 Iron oxide and a carbonate such as strontium (Sr) or barium (Ba) were used as raw materials, and these were mixed at a predetermined molar ratio. 13 mixed ingredients
After calcining at a temperature of 30 ° C., the calcined body was pulverized using a ball mill or the like to obtain a magnetoplumbite-type Sr ferrite powder. After subjecting this powder to a heat treatment at 1100 ° C. for 1 hour, the magnetic properties of the powder were measured using VSM. Table 2 shows the measurement results.

[0049]

[Table 2]

As can be seen from Table 2, according to the present invention,
Residual magnetic flux density B at a level comparable to the comparative example_rYou
And saturation magnetization J_sWhile maintaining higher security
Magnetic force H _cJCan show hard ferrite magnet
You.

(Example 2) Ferrous chloride and strontium chloride
SrO.5.8Fe in terms of oxide in terms of oxide _TwoO_ThreeWhen
It was weighed so as to be dissolved in pure water. Ferrous chloride concentration
The degrees are 23, 25, 27, 29, 31, 33, 35 and
And 37%. Add ethanol to this solution and add
The ethanol concentration with respect to was 40%. The resulting solution
Into a spray roasting furnace with a body atmosphere temperature of 1080 ° C
To form a powder. Additive to powder (CaCO_Three: 0.
9%, SiO_Two: 0.45%) and using pure water solvent
Thus, a 45% slurry liquid was prepared. 1 hour with wet ball mill
After performing the mixing process between, through the wet press molding process,
A sintering step was performed. Sintering is performed at a maximum sintering temperature of 1210 ° C.
Ran. FIG. 3 shows the residual magnetic flux density of the sintered body thus obtained.
B_rIs shown. As can be seen from FIG.
When the concentration of ferrous chloride is 25-35%,
Magnetic flux density B_rIs preferably 0.35 Tesla or more.
In addition, the concentration of 27-33% ferrous chloride is 27-33%.
In some cases, favorable characteristics are exhibited.
Those showing good properties were obtained.

As a result of experiments by the present inventors, it has been found that if the concentration of ferrous chloride is too low outside the above-mentioned preferable range, the particle size obtained by spraying is too small, which is not preferable. It was also found that when the concentration of ferrous chloride was too high outside the above-mentioned preferred range, precipitation and the like occurred in the solution to be sprayed, and the uniformity of the powder composition was lowered, which was not preferable.

(Example 3) SrO.
Ferrous chloride and strontium chloride were weighed so that 5.8 Fe ₂ O ₃ was obtained, and these were dissolved in pure water.
At this time, the concentration of ferrous chloride was 29%. Ethanol was added to this solution to adjust the concentration of ethanol to the solution to 40%.

The above solution was sprayed into a spray roasting furnace having a body atmosphere temperature of 700 to 1350 ° C. to form a powder. Additives to powder (CaCO ₃ : 0.9%, SiO ₂ : 0.45)
%), And a 45% slurry liquid was prepared using a pure water solvent. After performing the mixing process for 1 hour in a wet ball mill,
A sintering process was performed through a wet press molding process. Sintering was performed at a maximum sintering temperature of 1210 ° C. Figure 4 shows the remanence B _r of the sintered bodies obtained in this way. FIG.
As can be seen from FIG.
Preferably, the temperature is about 300 ° C. and the ambient temperature is about 110 ° C.
The best properties are obtained at 0 ° C.

When the furnace atmosphere temperature during spraying is low, unreacted iron oxide (α-Fe) is contained in the powder obtained by spraying.
₂ O ₃ ) and / or strontium chloride (SrC
l ₂ ) of the powder particles. Therefore, when the ambient temperature is below 1000 ° C., the residual magnetic flux density B _r decreases as decrease in ambient temperature. However, as will be described in detail below, if an additional heat treatment is performed on the mixed powder of ferrite, iron oxide, and / or strontium chloride, unreacted powders easily react with each other, and ferrite formation is promoted. . As a result, a hard ferrite magnet showing sufficient magnetic properties can be obtained. Therefore, when heat treatment is performed later, the ambient temperature during spraying is 800 to 1000 ° C.
May be in the range. However, if the ambient temperature at the time of spraying is 1000 ° C. or higher, no additional heat treatment step is required, and the manufacturing process is simplified, which is suitable for mass production.

Meanwhile, if the furnace atmosphere temperature during the spray is high, particles obtained by spray are aggregated, the magnetic orientation degree of the sintered body decreases, there is a tendency that the residual magnetic flux density B _r decreases . Therefore, the temperature during spraying is 1200 ° C.
It is desirable that:

From the above, the furnace atmosphere temperature during spraying was 8
It is preferably from 1000 to 1300 ° C, and from 1000 to 1300 ° C.
It can be said that 200 ° C. is more preferable.

In this embodiment, during the spraying, the powder was dropped while floating in the furnace for about 10 to 20 seconds, for example, and was directly exposed to the heating atmosphere.

Example 4 Ferrous chloride and strontium chloride weighed so that the ferrous chloride concentration was 29% and the strontium chloride concentration was 2.0 to 5.0% were dissolved in pure water. . Ethanol was added to this solution to adjust the concentration of ethanol to the solution to 40%. The obtained solution was sprayed into a spray roasting furnace having a body atmosphere temperature of 1080 ° C. during spraying, and a sintered body was prepared from the obtained powder in the same manner as in Example 2.

[0060] Figure 5 shows the remanence B _r of the sintered bodies obtained in this way. As can be seen from FIG. 5, the concentration of strontium chloride is preferably in the range of 2.4 to 4.4%, and the best characteristics were obtained at about 3.3%. This is because when the concentration of strontium chloride is in this range, the molar ratio of strontium to iron is optimized, and strontium ferrite having a desired composition is obtained.

(Example 5) Ferrous chloride, strontium chloride, lanthanum chloride,
Cobalt chloride was dissolved in pure water. Ethanol was added to this solution to adjust the concentration of ethanol to the solution to 40%. The body atmosphere temperature at the time of spraying the obtained solution is 1080.
The powder was sprayed into a spray roasting furnace at a temperature of ℃. A sintered body was produced from this powder in the same manner as in Example 2. Figure 6 shows a B _r of the sintered bodies obtained in this way. As can be seen from FIG. 6, the best characteristics were obtained with the composition of x = y = 0.2.

[0062]

[Table 3]

The basic composition of the Sr ferrite obtained in this example is (1-x) SrO. (X / 2) La.
It has a magnetoplumbite-type hexagonal structure represented by ₂ O ₃ · (ny / 2) Fe ₂ O ₃ · yCoO. Here, x, y and n indicate a molar ratio, and 0.05 ≦ x ≦
0.2, 0.05 ≦ y ≦ 0.2, 5.0 ≦ n ≦ 6.5.

According to the experiment, the mixed solution used for producing the above ferrite was FeCl ₂ : 25 to 35.
_{%, SrCl 2: 1.9~4.2%,} LaCl 3: 0.1
6~1.18%, CoCl _2: is preferably from 0.09 to 0.73% of water or hydrochloric acid solution. By using this mixed solution, a ferrite structure in which part of Fe is replaced by Co and part of Sr is replaced by La is obtained. Such substitutions improve magnetic properties.

Example 6 Ferrous chloride and strontium chloride were weighed so as to be SrO.5.8Fe ₂ O _{3 in} terms of oxide and dissolved in pure water. The concentration of ferrous chloride was 29%. The obtained solution was sprayed into a spray roasting furnace having a body atmosphere temperature of 900 ° C. during spraying to produce powder. After the obtained powder was heat-treated in the atmosphere at 700 to 1300 ° C. for 3 hours, a substance constituting the powder was identified using an X-ray diffractometer. Table 4 shows the results. As can be seen from Table 4, the temperature of the heat treatment performed on the powder was 10
When the temperature exceeds 00 ° C, almost magnetoplumbite Sr
A ferrite single phase powder is produced.

The magnetic properties of the powder were measured using a VSM. Results The results are shown in FIG. As can be seen from FIG. 7, the temperature of the additional heat treatment is preferably in the range of 800 to 1200 ° C. from the viewpoint of improving the residual magnetic flux density. However, if the heat treatment temperature exceeds 1050 ° C., grain growth occurs remarkably during the heat treatment, resulting in a decrease in coercive force. Therefore, in order to improve the characteristics of both the residual magnetic flux density and the coercive force, the range of the heat treatment temperature is set to 9
It is preferable to set the temperature within the range of 00 to 1050 ° C.

[0067]

[Table 4]

It should be noted that such a heat treatment also has a secondary effect of sufficiently volatilizing chlorine remaining in powder particles generated by spraying. Therefore, even if the powder particles obtained by spraying are sufficiently ferritized, it is significant to perform additional heat treatment. Further, additional heat treatment may promote powder particle growth.

In the above embodiment, a sintered magnet was manufactured using ferrite magnetic powder generated by spraying, but the present invention is not limited to this. A bonded magnet may be manufactured using the ferrite magnetic powder.

[0070]

According to the present invention, a fine ferrite magnetic powder of sub-crons having a uniform particle size can be obtained, so that the magnetic properties of a magnet manufactured using the ferrite magnetic powder are improved.
In addition, since the magnetic powder manufacturing process is shortened, manufacturing costs are reduced.

Further, a magnetoplumbite-type hexagonal ferrite can be produced at a lower heat treatment temperature as compared with the conventional method. Heat treatment equipment can be reduced in size, or energy consumption can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one configuration example of a spray roasting furnace suitably used in a method for producing ferrite magnetic powder according to the present invention.

FIG. 2 is a graph showing a relationship between an amount of ethanol added to a spray solution and a residual magnetic flux density (B _r ) of a ferrite magnetic powder sintered body.

FIG. 3 shows the composition of the spray solution as ferrous chloride and strontium chloride.
SrO · 5.8Fe_TwoO_ThreeAnd fixed
Ferrous chloride concentration and residual magnetic flux density (B
_rFIG.

FIG. 4 shows a spray roasting furnace in which the composition of the spray solution is fixed at SrO · 5.8Fe ₂ O ₃ and the ferrous chloride concentration is 29% in terms of oxide weight of ferrous chloride and strontium chloride. 5 is a graph showing a relationship between a body atmosphere temperature during spraying and a residual magnetic flux density (B _r ) of a sintered body.

FIG. 5 is a graph showing the relationship between the concentration of strontium chloride and the residual magnetic flux density (B _r ) of a sintered body when the concentration of ferrous chloride is fixed at 29 ° C., and the atmosphere temperature of the body in the spray roasting furnace is fixed at 1080 ° C. It is a graph showing the relationship.

FIG. 6 shows the composition (1) when the concentration of ferrous chloride is fixed at 29% and the body temperature at the time of spraying in a spray roasting furnace is fixed at 1080 ° C.
-X) SrO · (x / 2 ) La 2 O 3 · (5.5-y /
2) A graph showing the relationship between x, y in Fe ₂ O ₃ .yCoO and the residual magnetic flux density (B _r ) of the sintered body.

FIG. 7 is a graph showing a relationship between magnetic properties of a powder produced by a spray pyrolysis method and a heat treatment temperature when the powder is heat-treated.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Spray roasting furnace 12 Opening 13 Furnace interior 14 Nozzle 16 Ferrite powder

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G002 AA08 AA10 AB03 AC02 AE02 4G004 EA01 4G018 AA01 AA09 AA13 AA22 AB04 AC01 AC16 4G030 AA09 AA13 AA27 AA28 BA01 BA13 CA01 GA01 GA05 GA33 5E040 AB04 CA01 HB17 NN02 NN18

Claims (13)

[Claims] 1. A method for producing magnetoplumbite-type ferrite magnetic powder, comprising a step of producing a ferrite raw material powder by spraying a mixed solution in which iron chloride and strontium chloride are dissolved in a heated atmosphere. the mixed solution, a method of manufacturing magnetoplumbite ferrite magnetic powder, wherein 25% or more than 35% of FeCl _2, which and 2.4% more than 4.4% or less of SrCl ₂ is dissolved . 2. A method for producing a magnetoplumbite-type ferrite magnetic powder, which comprises a step of producing a ferrite raw material powder by spraying a mixed solution in which iron chloride and strontium chloride are dissolved in a heated atmosphere. The method for producing magnetoplumbite-type ferrite magnetic powder, wherein the mixed solution further contains a chloride of cobalt and a chloride of lanthanum. 3. The mixed solution contains 25% or more and 35% or less of FeCl ₂ , 1.9% or more and 4.2% or less of SrCl ₂ , 0.09% or more and 0.73% or less of CoCl ₂ , and _{3. The} method for producing magnetoplumbite-type ferrite magnetic powder according to claim 2, wherein 0.16% to 1.18% of LaCl ₃ is dissolved. 4. The method for producing magnetoplumbite ferrite magnetic powder according to claim 1, wherein a flammable solvent is mixed with the mixed solution. 5. The spray of the mixed solution has a temperature of 800 ° C.
The method for producing magnetoplumbite-type ferrite magnetic powder according to claim 1, wherein the method is performed in a furnace at a temperature of 1300 ° C. or lower. 6. The spray of the mixed solution has a temperature of 1000.
The method for producing magnetoplumbite-type ferrite magnetic powder according to claim 5, wherein the method is carried out in a furnace at a temperature of not less than 1200C and not more than 1200C. 7. The method for producing a magnetoplumbite ferrite magnetic powder according to claim 1, wherein the concentration of FeCl _{2 in} the mixed solution is 27% or more and 33% or less. 8. The method according to claim 7, wherein a waste liquid generated by pickling at an ironworks is used as a raw material of the mixed solution. 9. The method according to claim 8, wherein the spraying of the mixed solution is performed using a hydrochloric acid recovery device in the steel mill.
The method for producing a magnetoplumbite-type ferrite magnetic powder described in 1 above. 10. The method for producing a magnetoplumbite-type ferrite magnetic powder according to claim 1, further comprising a step of performing a heat treatment on the ferrite raw material powder. 11. The heat treatment is performed at 800 ° C. or more and 1200 ° C.
The method according to claim 10, wherein the method is performed at the following temperature. 12. The heat treatment is performed at 900 ° C. or higher and 1050 ° C.
The method according to claim 11, wherein the method is performed at the following temperature. 13. A step of preparing a magnetoplumbite-type ferrite magnetic powder manufactured by the method of manufacturing a ferrite magnetic powder according to claim 1, and a step of manufacturing a permanent magnet using the ferrite magnetic powder. A method for producing a ferrite magnet comprising: