JP2001335361A - Ferrite material powder and method for manufacturing ferrite magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetplumbite-type ferrite material powder having fine particles, sharp particle distribution and uniform composition, at a low manufacturing cost. SOLUTION: The chloride-dissolved mixture solution containing a chloride of iron, a chloride of strontium and at least one chloride of metal selected from lanthanum, cobalt, manganese and nickel is sprayed into a roasting furnace 10 in the heated atmosphere, and the chloride-dissolved mixture solution is changed to the magnetoplumbite-type ferrite material powder 16. In this process, an inflammable gas and/or oxygen gas are blown into or an inflammable solvent is sprayed into the area 17 where the above chloride-dissolved solution is changed into the magnetoplumbite-type ferrite material powder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a ferrite raw material powder by a spray pyrolysis method and a method for producing a ferrite magnet using the raw material powder.

[0002]

2. Description of the Related Art Ferrite is a general term for a compound formed from a divalent cation metal oxide and a trivalent iron oxide. Ferrite magnets are used for various applications such as rotating machines and speakers. I have. As a material for ferrite magnets,
Sr ferrite (SrFe ₁₂ O ₁₉ ) or Ba ferrite (Ba) having a hexagonal M-type magnetoplumbite structure
Fe ₁₂ O ₁₉ ) is widely used. The basic composition of M-type magnetoplumbite structure ferrite is usually AO · 6
It is represented by the chemical formula of Fe ₂ O ₃ . The element A is a metal that becomes a divalent cation, and is selected from Sr, Ba, Pb, Ca, and the like. These ferrites are produced at relatively low cost by powder metallurgy using iron oxide and carbonates such as strontium (Sr) and barium (Ba) as raw materials.

[0003]

However, the above conventional manufacturing method has the following problems.

(1) Since a 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) The cost increases because the calcining temperature is as high as 1150-1400 ° C.

(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 deviation of the composition 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 a fine ferrite raw material powder having a uniform composition and particle size.

[0008]

The method for producing a raw material powder of magnetoplumbite type ferrite according to the present invention comprises spraying a mixed chloride aqueous solution in which iron chloride and strontium chloride are dissolved into a roasting furnace in a heating atmosphere. Converting the mixed chloride aqueous solution into a magnetoplumbite-type ferrite raw material powder by applying a combustible gas and / or oxygen to a region where the mixed chloride aqueous solution is converted into a magnetoplumbite-type ferrite raw material powder. Injecting gas.

Another method for producing a magnetoplumbite-type ferrite raw material powder according to the present invention is characterized in that a mixed chloride aqueous solution in which iron chloride and strontium chloride are dissolved is sprayed into a roasting furnace in a heated atmosphere. A step of changing the mixed chloride aqueous solution into a magnetoplumbite-type ferrite raw material powder, and a step of spraying a flammable solvent onto a region where the mixed chloride aqueous solution is changed into a magnetoplumbite-type ferrite raw material powder. .

In a preferred embodiment, the mixed chloride aqueous solution contains at least one selected from the group consisting of iron chloride and strontium chloride, and lanthanum, cobalt, manganese and nickel chloride.
The seed chloride is dissolved, and the mixed chloride aqueous solution is acidic.

The spraying of the mixed chloride aqueous solution has a temperature of 8
It is preferably performed in a furnace at a temperature of from 00 ° C to 1300 ° C.

The temperature of the spray of the mixed chloride aqueous solution is 1
More preferably, it is performed in a furnace at a temperature of from 000 ° C to 1200 ° C.

In a preferred embodiment, a waste liquid produced by pickling in an ironworks is used as a raw material of the mixed chloride aqueous solution.

[0014] In a preferred embodiment, the mixed chloride aqueous solution is sprayed by using a hydrochloric acid recovery device in the steel mill.

In a preferred embodiment, the method further includes a step of performing a heat treatment on the ferrite raw material powder. The heat treatment is preferably performed at a temperature of 800 ° C. or more and 1200 ° C. or less.

The method for producing a ferrite magnet according to the present invention comprises the steps of preparing a ferrite raw material powder produced by any of the above-described methods for producing a magnetoplumbite ferrite raw material powder, and forming a permanent magnet using the ferrite raw material powder. And a manufacturing step.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventor has sprayed a mixed chloride aqueous solution in which iron chloride and strontium chloride are dissolved into a roasting furnace in a heating atmosphere, whereby the composition and particle size are uniform and fine. Various experiments for producing magnetoplumbite-type ferrite raw material powder were performed. As a result, by injecting a combustible gas and / or an oxygen gas into a region where the mixed chloride aqueous solution in the roasting furnace is converted into a magnetoplumbite type ferrite raw material powder, the temperature of the region where the ferrite conversion reaction occurs can be effectively reduced. It has been found that the raw material powder of magnetoplumbite-type ferrite can be efficiently produced at a relatively low roasting furnace temperature.

The inventor has also proposed that a region where the mixed chloride aqueous solution in the roasting furnace is converted into a magnetoplumbite-type ferrite raw material powder is sprayed with a flammable solvent, so that the region where the ferrite-forming reaction occurs also occurs. Has been found to be able to effectively increase the temperature, and thereby the raw powder of magnetoplumbite-type ferrite can be efficiently produced at a relatively low temperature in the roasting furnace.

If a raw material powder substantially consisting of magnetoplumbite type ferrite is produced by the spray pyrolysis method, various steps such as calcination and pulverization can be omitted in the ferrite production process, so that the productivity is reduced. Improved and reduced manufacturing costs. In addition, it is possible to avoid the problem that the characteristics of the product are deteriorated due to foreign substances being mixed in the pulverizing step, the composition being shifted, and the particle size distribution being broadened due to the formation of ultrafine powder. Furthermore, since fine powder particles with a particle size of submicron level are generated,
The time of the subsequent pulverization step can be shortened, or the pulverization step itself can be omitted. In addition, in the mixed chloride aqueous solution, since the elements such as iron and strontium are uniformly dispersed at the atomic level, the uniformity of the composition between the powder particles is improved, and as a result, it is finally obtained. The composition of the magnet is also made uniform.

Further, according to the method of the present invention, since the temperature of the region where the ferrite-forming reaction occurs can be effectively raised, even if the temperature of the entire roasting furnace is relatively low, the magnetoplumbite type can be used. Ferrite raw material powder can be generated, and a reduction in manufacturing cost can be achieved.

The mixed chloride aqueous solution contains iron and strontium chlorides, which are main elements of magnetoplumbite ferrite, and at least one chloride selected from the group consisting of lanthanum, cobalt, manganese and nickel chlorides. And As described above, since at least one chloride selected from the group consisting of lanthanum, cobalt, manganese, and nickel chloride is contained in the mixed chloride aqueous solution, the raw powder of magnetoplumbite-type ferrite and The magnetic properties of the ferrite magnet made from the powder are improved.

The concentration of iron chloride contained in the mixed chloride aqueous solution is preferably from 20% by weight to 35% by weight. The concentration of strontium chloride contained in the mixed chloride aqueous solution is preferably 1.9% by weight or more and 4.9% by weight or less.

The concentration of lanthanum chloride contained in the mixed chloride aqueous solution is preferably from 0% by weight to 2% by weight. Further, cobalt contained in the mixed chloride aqueous solution,
The concentrations of manganese and nickel chloride, respectively,
It is preferably from 0% by weight to 1% by weight.

If the mixed chloride aqueous solution is left in the air for a long time, the iron compound precipitates and the composition uniformity of the solution is lost. By adding an acid such as hydrochloric acid to the aqueous solution and keeping the solution acidic, it is possible to prevent the formation of a precipitate in the aqueous solution, thereby maintaining the composition uniformity of the mixed chloride aqueous solution. The acidity of this aqueous solution is pH ≤
6 is preferable, and pH ≦ 2 is more preferable.

In the mixed chloride aqueous solution, if necessary,
₃ BO ₃ , B ₂ O _3, etc. in an amount of about 0.3% by weight or less and other compounds such as Ca, Si, Pb, Al, Ga, Cr, S
n, In, Co, Ni, Ti, Mn, Cu, Ge, N
b, Zr, Li, Mo, Bi, rare earth element (including Y)
And the like may be added in an amount of about 2% by weight or less.
If the amount is small, it may contain impurities such as unavoidable components.

As the aqueous solution of iron chloride, which is the main raw material of the aqueous solution of the mixed chloride, a waste liquid generated in a pickling step of hydrochloric acid of a steel plate or the like in a rolling step of an ironworks can be used. Aqueous chloride solutions such as strontium, lanthanum, cobalt, manganese and nickel include strontium carbonate, strontium chloride, lanthanum oxide, lanthanum chloride, cobalt oxide, cobalt chloride, metal manganese, manganese oxide, manganese chloride, metal nickel, nickel oxide, chloride It can be obtained efficiently by directly dissolving a strontium raw material such as nickel, a lanthanum raw material, a cobalt raw material, a manganese raw material and a nickel raw material in a hydrochloric acid or iron chloride solution.

The mixed chloride aqueous solution is preferably sprayed into a roasting furnace having a temperature of 800 ° C. or more and 1400 ° C. or less. When the temperature in the roasting furnace is lower than 800 ° C., the reaction of drying, thermal decomposition and oxidation of the sprayed aqueous solution is not sufficient, and a large amount of iron and strontium compounds such as iron and strontium chloride are contained in the prepared raw material powder. And remains unreacted. When the temperature is higher than 1300 ° C., the particles of the produced powder aggregate, and the degree of magnetic orientation of a sintered magnet or the like produced from the raw material powder is reduced. Further, when the temperature in the roasting furnace is 800 or more and less than 1000 ° C., the prepared raw material powder includes strontium such as iron oxide and strontium, lanthanum, cobalt, manganese, and nickel chloride in addition to magnetoplumbite-type ferrite. May contain lanthanum, cobalt, manganese, nickel compounds. Therefore, the mixed chloride aqueous solution has a temperature of 10
More preferably, it is sprayed into a roasting furnace at a temperature of from 00 ° C to 1300 ° C.

According to the present invention, a flammable gas or oxygen gas is blown into a region where the mixed chloride aqueous solution in the roasting furnace is changed into a raw material powder of magnetoplumbite type ferrite, or a flammable solvent is sprayed. The temperature of the reaction zone can be higher than the ambient temperature. For this reason, even when the furnace temperature is relatively low at 1000 ° C. or less,
In the reaction zone, a temperature sufficient for changing to magnetoplumbite ferrite can be obtained. Thereby, the running cost of the roasting furnace can be reduced. Further, by blowing a flammable gas and / or an oxygen gas or spraying a flammable solvent, the particle shape and the like of the prepared raw material powder can be improved. Magnetic properties are improved.

The flammable gas which can be suitably used in the present invention is, for example, LPG, LNG, coal gas, city gas, water gas, generator gas, hydrogen, carbon monoxide, methane, ethane, propane, butane, ethylene. , Propylene, butylene, acetylene and the like. Further, flammable solvents that can be suitably used in the present invention include, for example, methyl alcohol, ethyl alcohol, ether, acetone, benzene, gasoline, light oil and the like.

The temperature in the roasting furnace is 800 or more and 100 or more.
Even when the temperature is lower than 0 ° C., if an additional heat treatment is performed on the prepared raw material powder, unreacted powders easily react with each other,
Ferrite formation is promoted. As a result, hard ferrite magnetic powder exhibiting sufficient magnetic properties can be obtained. It is preferable that the temperature of the additional heat treatment be 800 ° C. or more and 1200 ° C. or less.

The additional heat treatment also has the effect of sufficiently removing chloride remaining in the raw material powder particles produced by the method according to the present invention. Therefore, even if the produced raw material powder is sufficiently ferritized, it is significant to perform additional heat treatment. Further, the raw material powder produced by the additional heat treatment may be grown to a desired average particle size.

The roasting furnace used in the production of the magnetoplumbite type ferrite raw material powder according to the present invention can be efficiently used as a roasting furnace for a hydrochloric acid pickling process used in a steel plate rolling process in a steel mill rolling process. A plumbite type ferrite raw material powder can be manufactured.

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 (indicated by a thick arrow 19 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. Region 17 where ferrite formation occurs is shown in FIG.
Is schematically represented by a broken line.

In the present invention, a flammable gas and / or an oxygen gas is blown into this region 17 or a flammable solvent is sprayed. Such a flammable gas and / or an oxygen gas or a flammable solvent is performed, for example, through the opening 18. In the figure, the gas or the solvent introduced through the opening 18 is indicated by a thick arrow 20.

In this manner, the temperature of the region 17 where the ferrite-forming reaction takes place can be effectively increased, whereby the raw material powder of the magnetoplumbite ferrite can be efficiently produced at a relatively low temperature in the roasting furnace. Can be manufactured.

The generated ferrite crystal powder 16 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.

Although the above-described furnace 10 uses a burner gas to heat the atmospheric gas, an electric heater may be used instead. In addition, air may be used as the atmosphere gas.

The region 17 where the ferrite-forming reaction takes place
The blowing of the flammable gas and / or the oxygen gas into and the spraying of the flammable solvent are not limited by the configuration shown in FIG. The position of the opening 18 may be provided at the same level as the position of the opening 12, or may be provided at a level lower than the position of the opening 12. The direction of gas blowing and the direction of solvent spray are not limited to those shown in the drawings. Furthermore,
A nozzle or the like may be inserted into the opening 18.

[0039]

Embodiments of the present invention will be described below.

Example 1 First, Sr in terms of oxide equivalent weight.
O · 5.8Fe ₂ O ₃ so that FeCl ₂ and S
rCl ₂ was weighed and dissolved in pure water. At this time, the concentration of FeCl ₂ was adjusted to be 28% by weight, and pH = 0 by adding hydrochloric acid to the solution. This solution is blown with oxygen gas into a region to be converted into a magnetoplumbite ferrite raw material powder, and sprayed into a roasting furnace having a temperature of 1100 ° C. in the region to produce a magnetoplumbite ferrite raw material powder. did.

At the stage where the oxygen gas was not blown, the temperature of the region was 1000 ° C., and in this case, the temperature of the region was raised by 100 ° C. by blowing oxygen.

The composition of the prepared raw material powder was Fe: Sr =
The ratio was 91: 9 (weight ratio), and almost no composition deviation was observed. In addition, as a result of examination with an X-ray diffractometer, it was almost single-phase SrFe ₁₂ O ₁₉ . In addition, when the magnetic characteristics were examined with a sample vibration magnetometer (VSM), the results were as shown in Table 1, and excellent characteristics were obtained.

Next, 0.9% by weight of CaCO ₃ and 0.45% by weight of SiO ₂ were added to the prepared raw material powder to form a 45% slurry with a pure water solvent and mixed for 1 hour with a wet ball mill. Press molding was performed in a magnetic field while removing the solvent in the slurry. The compact was sintered at 1210 ° C. for 30 minutes. The magnetic properties of the obtained sintered magnet are as shown in Table 2,
It can be seen that the characteristics are excellent.

Similarly, from the above raw material powder, C
Sintered magnets were fabricated and replaced with conventional sintered magnets in a motor, and operated under rated conditions. As a result, good characteristics were obtained. Also, when the torque was measured, it was higher than before.

When a bonded magnet was prepared from the above raw material powder, the same result as that of the sintered magnet of this example was obtained.

When the above raw material powder was used for a magnetic recording medium, a high output and a high S / N were obtained.

When a magnetic recording medium having a thin-film magnetic layer was produced by sputtering using the above raw material powder as a target, a high output and a high S / N were obtained.

(Example 2) A magnetoplumbite-type ferrite raw material powder and a sintered magnet were produced in the same manner as in Example 1, except that ethanol was sprayed as a flammable solvent in a region to be changed to the magnetoplumbite-type ferrite raw material powder. . The temperature of the area is 80 ° C by spraying ethanol.
The temperature rose to 1080 ° C.

In Example 2, the magnetic properties of the raw material powder and the sintered magnet were as shown in Tables 1 and 2, and were excellent.

[0050] (Comparative Example 1) Fe ₂ O ₃ and SrCO ₃ were used as starting materials and mixed so that SrO · 5.8Fe ₂ O ₃ in terms of oxides by weight, 3 hours calcined Mr 1300 ° C. in air Then, the mixture was pulverized with a roller mill to prepare a calcined ferrite magnet powder. After heat treatment of this powder at 1100 ° C. for 1 hour, the magnetic properties were measured using VSM, and the results shown in Table 1 were obtained. Further, when a sintered magnet was produced from the produced ferrite calcined magnet powder in the same manner as in Example 1, the magnetic properties were as shown in Table 2.

(Comparative Example 2) Except that the mixed chloride aqueous solution was sprayed into a roasting furnace having a temperature of 1000 ° C. without blowing oxygen gas or the like into the region to be changed to the magnetoplumbite type ferrite raw material powder. Produced a raw material powder of magnetoplumbite ferrite and a sintered magnet in the same manner as in Example 1. These magnetic properties are shown in Tables 1 and 2.
It was as follows.

[0052]

[Table 1]

[0053]

[Table 2]

(Examples 3 to 9 and Reference Examples 1 and 2) FeC was added so that SrO · 5.8Fe ₂ O _{3 in} terms of oxide was obtained.
l ₂ and SrCl ₂ were weighed and dissolved in pure water. At this time, the concentration of FeCl ₂ was adjusted to be 28% by weight. 0.93% by weight of LaCl ₃ was added to this solution.
When added (Example 3), when 0.49% by weight of CoCl ₂ was added (Example 4), when 0.48% by weight of MnCl ₂ was added (Example 5), 0.49% by weight of NiCl ₂ was added.
% By weight (Example 6), 0.5% ZnCl ₂ was added.
When 2% by weight was added (Reference Example 1), CuCl ₂ was added in an amount of 0.
When 49% by weight was added (Reference Example 2), when 0.93% by weight of LaCl ₃ and 0.49% by weight of CoCl ₂ were added (Example 7), 0.93% by weight of LaCl ₃ and Mn were added.
When 0.48% by weight of Cl ₂ was added (Example 8), L
0.93% by weight of aCl ₃ and 0.49% by weight of NiCl ₂
In each case of the addition (Example 9), a magnetoplumbite-type ferrite raw material powder and a sintered magnet were produced in the same manner as in Example 1. The magnetic properties of these sintered magnets are as shown in Table 3 and were excellent.

[0055]

[Table 3]

[0056]

According to the present invention, it is possible to produce a magnetoplumbite-type ferrite raw material powder having a fine and sharp particle size distribution and a uniform composition, and the quality of the ferrite magnet produced using this ferrite raw material powder is improved. The characteristics can be improved.

In addition, since various steps such as calcination and pulverization in the conventional steps can be omitted, and the operation in the roasting furnace can be performed at a relatively low temperature, the productivity is improved and the production cost is reduced. You.

[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.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Spray roasting furnace 12 Burner gas introduction opening 13 Inside of furnace 14 Nozzle 16 Ferrite raw material powder 17 Region where ferrite is formed 18 Opening for introduction of flammable gas, oxygen gas, flammable solvent 19 Thick arrow indicating burner gas 20 Thick arrows indicating flammable gas, oxygen gas and flammable solvent

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 4G002 AA08 AB02 AC02 AE02 4G018 AA01 AA09 AA13 AA21 AA22 AA23 AB04 AC13 AC16 5E040 AB04 AB09 BD01 CA01 HB00 HB01 HB09 HB15 HB17 NN18 5E062 CC01 CD01 CD01 CE04 CF01 CG01 CG02

Claims (10)

[Claims] 1. A mixed chloride aqueous solution in which iron chloride and strontium chloride are dissolved is sprayed into a roasting furnace in a heating atmosphere to convert the mixed chloride aqueous solution into a magnetoplumbite type ferrite raw material powder. A method for producing a magnetoplumbite-type ferrite raw material powder, comprising: a step of injecting a combustible gas and / or an oxygen gas into a region where the mixed chloride aqueous solution is changed into the magnetoplumbite-type ferrite raw material powder. 2. A mixed chloride aqueous solution in which iron chloride and strontium chloride are dissolved is sprayed into a roasting furnace in a heating atmosphere to convert the mixed chloride aqueous solution into a magnetoplumbite type ferrite raw material powder. A method for producing a magnetoplumbite-type ferrite raw material powder, comprising: a step of spraying a flammable solvent onto a region where the mixed chloride aqueous solution is converted into the magnetoplumbite-type ferrite raw material powder. 3. The mixed chloride aqueous solution includes iron chloride and strontium chloride, and lanthanum;
3. The mixed chloride aqueous solution according to claim 1, wherein at least one chloride selected from the group consisting of cobalt, manganese, and nickel chlorides is dissolved, and the mixed chloride aqueous solution is acidic. Manufacturing method of magnetoplumbite type ferrite raw material powder. 4. The magnetoplumbite ferrite according to claim 1, wherein the spraying of the mixed chloride aqueous solution is performed in a furnace having a temperature of 800 ° C. or more and 1300 ° C. or less. Production method of raw material powder. 5. The method according to claim 4, wherein the spraying of the mixed chloride aqueous solution is performed in a furnace having a temperature of 1000 ° C. or more and 1200 ° C. or less. . 6. The method for producing a magnetoplumbite-type ferrite raw material powder according to claim 1, wherein a waste liquid generated by pickling at an ironworks is used as a raw material of the mixed chloride aqueous solution. . 7. The method for producing a magnetoplumbite-type ferrite raw material powder according to claim 6, wherein the spraying of the mixed chloride aqueous solution is performed using a hydrochloric acid recovery device in the steel mill. 8. The method for producing a magnetoplumbite-type ferrite raw material powder according to claim 1, further comprising a step of performing a heat treatment on the ferrite raw material powder. 9. The method of claim 8, wherein the heat treatment is performed at a temperature of 800 ° C. or more and 1200 ° C. or less. 10. A step of preparing a ferrite raw material powder produced by the method for producing a magnetoplumbite ferrite raw material powder according to any one of claims 1 to 9,
Producing a permanent magnet using the ferrite raw material powder.