JP2746736B2 - Method for producing composite oxide for ferrite raw material - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing ferrite, and more particularly to a composite for a high-grade soft ferrite raw material using a metal chloride or oxide constituting soft ferrite as a raw material. The present invention relates to a method for producing an oxide.

[Prior art] An industrial method for producing ferrite is to mix a compound such as iron or manganese (or magnesium, nickel or the like) or a metal oxide or carbonate such as zinc in a predetermined molar ratio. In general, high-temperature sintering is generally performed after calcination (preliminary sintering), pulverization, and molding steps. However, this method requires a calcining step at a relatively high temperature and for a long time, and in addition to quality influences such as contamination of impurities during the manufacturing process and nonuniformity of quality when viewed microscopically, There is a problem that it takes a long time to manufacture and the amount of required energy increases.

In general, the iron oxide raw material that accounts for the largest proportion of the ferrite raw material composition is obtained in many cases by subjecting a steel plate hydrochloric acid pickling waste liquid in a rolling process of an ironworks to high-temperature oxidation roasting in a spray roasting furnace.

As a method of producing ferrite which improves the prior art, a production method has been proposed in which a chloride mixed solution of a metal constituting ferrite is used as a starting material and oxidized and roasted (Japanese Patent Publication No. 47-11550).

However, if all starting materials are used in the form of metal chlorides, metal chlorides having a high vapor pressure, such as zinc chloride, will volatilize during roasting, and the concentration of the metal in products formed from the roasting furnace bottom will be reduced. In this case, there is a problem that the value is significantly lower than the target value.

In Japanese Patent Publication No. 63-17776, among the metals constituting ferrite, only the metal having a low vapor pressure of chloride is converted into a mixed oxide by oxidizing and roasting as a mixed chloride solution. A method has been proposed in which a ferrite is produced by mechanically mixing an oxide of a metal having a high vapor pressure as a chloride and then directly sintering it without going through a calcination step.

Although this method has a considerable improvement effect as compared with the above-mentioned method starting from individual powder oxides, the step of mechanical mixing of metal oxides is still left, and from the viewpoint of uniform dispersibility, However, the improvement is hardly enough. That is,
As shown in the publication, if the calcination step is omitted, the uniform mixing property of the metal oxide (generally zinc oxide) is reduced, and the probability of the change during firing and the adhesion of the products are high. And lower the product yield.

[Problems to be solved by the invention]

As described above, in the method for producing a composite oxide for a soft ferrite raw material, a metal chloride having a high vapor pressure such as zinc cannot be simultaneously roasted in a high-temperature roasting step, and mechanical Therefore, there is still room for improvement in terms of uniform dispersibility or contamination with impurities.

Therefore, the present inventors have focused on the above-described problems, and as a result of repeated testing and research, have found that zinc oxide is
By mixing and suspending in a manganese (or magnesium, nickel, etc.) chloride aqueous solution and supplying it simultaneously to the furnace, the main metal constituting soft ferrite 3
It has been discovered that the elements can be reacted simultaneously in the same roasting furnace and the powder composite oxide can be recovered from the furnace bottom with a high yield.

The present invention provides a method for manufacturing a soft ferrite raw material which can be directly fired in a single step without sintering and powder mixing steps in the ferrite manufacturing process and without causing deformation during firing and adhesion of products. The purpose is to do so.

[Means for solving the problem]

The present inventors have conducted intensive studies on a method for producing a complex oxide for a soft ferrite raw material that is inexpensive and efficient in order to achieve the above object, and as a result, a component having a high vapor pressure as a metal chloride such as zinc is obtained. A solution to the problem of volatilization during roasting was found, and the following invention was completed.

That is, the present invention, iron and manganese which are the main elements constituting ferrite, magnesium, magnesium, when producing a powder composite oxide by spray roasting a chloride mixed solution such as nickel, iron chloride, manganese , A mixed chloride aqueous solution containing at least one selected from chlorides of magnesium and nickel, is neutralized with a neutralizing agent to obtain a neutralized chloride mixed solution having a pH of 3.5 or more. This is a method for producing a composite oxide for a ferrite raw material, which comprises spraying and oxidizing and roasting the slurry within 30 minutes after adding and suspending the oxide to form a slurry.

In the present invention, the term "neutralized chloride mixed solution" refers to a solution obtained by neutralizing the free hydrochloric acid component of a mixed chloride solution of iron, manganese, magnesium, nickel or the like with a neutralizing agent comprising the metal.

[Action]

 Hereinafter, the specific configuration of the present invention will be described together with its operation.

Generally most of what is industrially mass-produced soft ferrites are, Fe ₂ O _3: about ^{70wt% M 2+ O: 15~30wt%} ( here M represents Mn, Mg, and Ni, etc.) ZnO: 0 It is constituted as ~ 15wt%. Of these, zinc has a high vapor pressure as a chloride as described above, and when spray roasting at the same temperature as other metals, a large amount of zinc chloride is discharged from the furnace top and contained in oxides recovered from the furnace bottom. Zinc yield is significantly reduced.

Therefore, in the present invention, a new roasting method for supplying zinc as an oxide powder is as follows. That is, a mixed chloride solution of iron and another metal (manganese, magnesium, nickel, etc.) is used as a raw material, and after neutralizing free hydrochloric acid with the metal, a zinc oxide powder and / or a zinc oxide water slurry is added. Slurry liquid, and then quickly supply it into a spray roasting furnace before the metal substitution reaction between zinc and a metal having a lower ionization tendency than zinc (iron, nickel, etc.) and simultaneously perform oxidizing roasting Is the biggest feature.

 The following is a description based on a specific flow.

FIG. 1 is a block diagram showing a production process of a raw material composite oxide for Mn—Zn ferrite according to the present invention.

The aqueous solution of iron chloride, which is the main raw material of the mixed roasting, is obtained as a hydrochloric acid pickling waste liquid such as a steel sheet in a rolling process of an ironworks. Raw materials,
It is obtained by directly dissolving in hydrochloric acid or an aqueous solution of iron chloride.

First, the mixed aqueous solution 1 of Fe and Mn chlorides is neutralized in a neutralization tank 2 with a neutralizing agent 3 to have a pH of 0.35 or more, preferably pH = 0.
Neutralized to 7 or more. At a pH of less than 0.35, when zinc oxide 5 is mixed with and suspended in the mixed chloride 1, zinc oxide 5 is dissolved by free hydrochloric acid in the chloride by 60% or more to form chloride. In this case, when roasting in the spray roasting furnace 8, the zinc chloride having a high vapor pressure volatilizes during the roasting, and the zinc in the product 11 generated from the furnace bottom of the roasting furnace 8 is about 30% of its target concentration. Problem arises.

The neutralized chloride mixture 4 is then led to a mixer 6 where zinc oxide powder or a water slurry 5 is added and mixed.
And a zinc oxide slurry solution 7 of a mixed chloride aqueous solution of Mn. The zinc oxide 5 supplied to the mixer 6 is desirably supplied as a powder so as not to lower the concentration of the zinc slurry solution 7 of the mixed chloride aqueous solution, but may be supplied as a water slurry. In the case of a water slurry, its concentration is
In order to reduce the amount of fuel used in the roasting furnace 8, it is desirable to use as high as possible. Therefore, it is desirable that the concentration be at least about 30% by weight, which is the upper limit that can be supplied by a normal slurry pump.

Zinc oxide slurry solution of mixed chloride aqueous solution of Fe and Mn 7
Is quickly supplied to the spray roasting furnace 8 before the metal substitution reaction between zinc suspended therein and a metal having a lower ionization tendency than zinc (Fe in the case of Mn-Zn ferrite) does not proceed. , And simultaneously oxidatively roasted. In this case, it is desirable that the zinc oxide slurry liquid 7 is supplied to the roasting furnace 8 within 30 minutes, preferably 5 minutes after the zinc oxide 5 is mixed, and oxidized and roasted.

FIG. 2 shows that zinc oxide 5 is added to the mixed chloride aqueous solution 1 of Fe and Mn.
FIG. 3 is a view showing a metal substitution reaction rate of zinc and iron when mixed. According to FIG. 2, about 65% in 30 minutes after mixing, about 20% of zinc was replaced with iron by metal in 5 minutes, and the mixed chloride aqueous solution 1
Is dissolved in Since the dissolved zinc becomes chloride, this zinc oxide slurry liquid 7 is mixed with zinc oxide.
When roasting is performed after 30 minutes or more, as described above, zinc chloride is volatilized during roasting, and zinc in the product 11 generated from the bottom of the roasting furnace 8 is less than about 30% of its target concentration.

Zinc oxide slurry solution of mixed chloride aqueous solution of Fe and Mn 7
Is sprayed into the spray roasting furnace 8 and is oxidized and roasted at a high temperature of 650 to 900 ° C. by burning the fuel 9 supplied to the roasting furnace 8. In the process of oxidative roasting, Fe and Mn undergo a spinelization reaction with zinc oxide, resulting in very uniform ZnFe ₂ O ₄ , ZnMn ₂ O ₄
, Etc. (intermediate to a single spinel phase). The combustion exhaust gas 10, the hydrogen chloride gas 10, and the evaporated water 10 are discharged from the upper part of the roasting furnace 8.

The composite oxide powder 11 thus obtained is made of SiO ₂ or
Add a small amount of additive 12 such as CaCO ₃ and mix and mold.
By directly firing at high temperature in step 3, it is possible to obtain a ferrite sintered core product 14 having excellent magnetic properties, no deformation and no cracks, and high dimensional accuracy.

Above, when manufacturing a powder composite oxide by mixing and roasting a mixed solution of chlorides of Fe and Mn, which are the main elements constituting ferrite, neutralizes the free hydrochloric acid content in the aqueous chloride solution of Fe and Mn. Then, after suspending zinc oxide in this neutralized chloride aqueous solution to form a slurry liquid, by feeding it into a roasting furnace within 30 minutes and spray roasting, Fe / Mn in the roasting single step / Zn
This makes it possible to uniformly mix, oxidize, and spinel, thereby eliminating the need for the mechanical mixing step and calcination of the zinc raw material, which are usually performed in the next step. The soft ferrite product thus obtained has excellent magnetic properties and dimensional accuracy.

〔Example〕

 Hereinafter, the present invention will be specifically described based on examples.

As an example, iron raw material (steel pickling waste liquid: ferrous chloride aqueous solution) and manganese raw material (solution of hydrochloric acid of iron-manganese alloy)
Was purified by filtration and then mixed at a predetermined molar ratio to prepare an aqueous chloride solution 1. FeCl ₂ 291 (g / l), MnCl ₂ 11
2 (g / l) and the pH was 0.1.

A neutralizing tank 2 filled with a scrap piece 3 of a cold-rolled steel sheet generated in an ironworks as a neutralizing agent 3 at least 10 times the theoretical consumption amount,
This solution 1 was continuously supplied and neutralized at 3.0 m ³ / hr to produce a neutralized chloride mixed solution 4. At this time, the average residence time of the liquid 1 in the neutralization tank 2 was 2.5 hours, and the pH of the neutralized chloride mixed solution 4 was
Was 1.5. FeCl ₂ rose to 339 (g / l).

Next, the neutralized chloride mixed solution 4 was introduced into the mixer 6 at a supply rate of 3.0 m ³ / hr, and mixed with 94.0 kg / hr of zinc oxide powder,
Three minutes later, the zinc slurry liquid 7 of the mixed chloride aqueous solution was supplied to the spray roasting furnace 8. The zinc oxide slurry solution 7 was collected immediately before spraying, and the zinc oxide was quickly separated by filtration. The amount of zinc oxide dissolved in the zinc oxide slurry solution 7 was measured, indicating that 18.2% of the total was dissolved.

When the zinc slurry solution 7 of the mixed chloride aqueous solution was roasted at the body atmosphere temperature of the roasting furnace 8 at 780 ° C., the composition of the mixed oxide powder 11 obtained from the furnace bottom was Fe: Mn: Zn: 67.9: 22.3: 9.8
(Weight ratio), and the zinc yield was 85.4%.
As a result of X-ray diffraction analysis, ZnFe ₂ O
₄ , reaction products such as ZnMn ₂ O ₄ and MnFe ₂ O ₄ were detected.

CaCO ₃ 8 is added to the mixed oxide powder 11 thus generated.
After adding 30 ppm and 120 ppm of SiO ₂ to make a 50% slurry solution by dissolving in pure water, mix with a wet attritor for 20 minutes, omit the calcining step, granulate with a spray drier, press-mold to toroidal core After that, the maximum sintering temperature in the firing furnace 13
When baked at 1360 ° C, the magnetic properties of the obtained core 14
The electrical characteristics were found to be excellent as shown in Table 1.

As a comparative example, ZnO was post-added to a Fe-Mn mixed oxide produced in the same manner as in the above example except for mixing immediately before roasting ZnO so as to have the same composition ratio, and the additive (CaCO ₃ 830pp
m, 120 ppm of SiO ₂ ), a wet attritor treatment was performed, and the mixture was fired under the conditions shown in the examples. The magnetic and electrical characteristics of the obtained core were as shown in Table 1.

[Effects of the Invention] As is clear from the above, if operated as in the present invention,
When producing Fe- (Mn, Mg, Ni) -Zn ferrite, it becomes possible to produce a composite oxide powder containing Zn in the same roasting furnace, and the Zn raw material in the conventional post-process The addition / mechanical mixing step can be omitted, and the quality characteristics of the ferrite core can be significantly improved. It is considered that the improvement in the magnetic and electric properties is due to the improvement in the uniform dispersibility of the oxides constituting the ferrite, particularly the zinc oxide.

Furthermore, when the calcination step is omitted, the intermediate phase (ZnFe ₂ O ₄ ) generated in the conventional firing step is generated in advance, so that volume expansion due to the formation of the intermediate phase during firing can be suppressed. . For this reason, a ferrite product having high dimensional accuracy can be manufactured at a high yield without finally having a high sintering density and without causing problems such as deformation, cracking, and adhesion of products.

As described above, the present invention has an effect that a high-quality powder mixed oxide for a ferrite raw material can be efficiently and economically produced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a production process of a raw material composite oxide for Mn-Zn ferrite according to the present invention, and FIG. 2 is a graph showing a metal substitution reaction rate between zinc and iron. DESCRIPTION OF SYMBOLS 1 ... Aqueous mixed solution of Fe and Mn chlorides 2 ... Neutralization tank 3 ... Neutralizing agent 4 ... Neutralized mixed chloride aqueous solution of Fe and Mn 5 ... Zinc oxide powder and / or water slurry 6 ... Mixer 7 ... Zinc oxide slurry solution of mixed chloride aqueous solution of Fe and Mn 8 ... Spray roasting furnace 9 ... Fuel 10 ... Combustion exhaust gas, hydrogen chloride gas and evaporated water 11 ... Composite oxide of three metals of Fe, Mn and Zn Powder 12 ... Trace additive 13 ... Firing furnace 14 ... Ferrite sintered core product

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Tetsu Nariya 1 Kawasaki-cho, Chiba-shi, Chiba Kawasaki Steel Corporation Research and Development Headquarters (72) Inventor Hidekazu Yoshimatsu 1 Kawasaki-cho, Chiba-shi, Chiba Kawasaki Steel (56) References JP-A-58-115027 (JP, A) JP-A-58-135132 (JP, A)

Claims (1)

(57) [Claims] A mixed chloride aqueous solution containing a chloride of iron and at least one selected from chlorides of manganese, magnesium and nickel is neutralized in a neutralization tank with a neutralizing agent to have a pH of 0.1.
A ferrite characterized by having a mixed solution of 35 or more neutralized chlorides, adding a powdery zinc oxide to the solution and suspending the slurry to form a slurry, and spraying and roasting the slurry within 30 minutes. A method for producing a composite oxide for a raw material.